Abstract:
The invention relates to apparatus and method for ultrasonically stimulating cartilage growth. The apparatus includes at least one ergonomically constructed ultrasonic transducer configured to cooperate with a placement module or strip for placement in proximity to an area where cartilage growth is desired. The apparatus also utilizes a portable, ergonomically constructed main operating unit constructed to fit within a pouch worn by the patient. In operation, at least one ultrasonic transducer positioned in proximity to an osteochondral site is excited for a predetermined period of time. To ensure that at least one ultrasonic transducer is properly positioned, and to insure compliance with a treatment protocol, a safety interlock is provided to prevent inadvertent excitation of the at least one ultrasonic transducer.

Description:
This application is a continuation-in-part application of U.S. Ser. No. 09/436,999 filed on Nov. 9, 1999 now U.S. Pat. No. 6,355,006, which is cip the U.S. national phase of International Application No. PCT/US98/02447 filed on Feb. 6, 1998, which claims priority to U.S. Provisional Application No. 60/037,367 filed on Feb. 6, 1997. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to methods and apparatus for therapeutically treating injuries using ultrasound. More particularly, the present invention relates to methods and apparatus which utilize an ergonomically constructed ultrasonic transducer assembly configured to cooperate with a placement module for placement in proximity to a cartilage and/or osteochondral injury and/or defect to stimulate cartilage growth. 
   2. Description of the Related Art 
   The use of ultrasound to therapeutically treat and evaluate bone injuries is known. Impinging ultrasonic pulses having appropriate parameters, e.g., frequency, pulse repetition, and amplitude, for suitable periods of time and at a proper external location adjacent to a bone injury has been determined to accelerate the natural healing of, for example, bone breaks and fractures. 
   U.S. Pat. No. 4,530,360 to Duarte describes a basic non-invasive therapeutic technique and apparatus for applying ultrasonic pulses from an operative surface placed on the skin at a location adjacent a bone injury. To apply the ultrasound pulses during treatment an operator must manually hold the applicator in place until the treatment is complete. 
   The Duarte patent as well as U.S. Pat. No. 5,520,612 to Winder et al. describe ranges of RF signal for creating the ultrasound, ultrasound power density levels, ranges of duration for each ultrasonic pulse, and ranges of ultrasonic pulse frequencies. 
   U.S. Pat. No. 5,003,965 to Talish et al. relates to an ultrasonic body treatment system having a body-applicator unit connected to a remote control unit by sheathed fiber optic lines. The signal controlling the duration of ultrasonic pulses and the pulse repetition frequency are generated apart from the body-applicator unit. Talish et al. also describes a mounting fixture for attaching the body-applicator unit to a patient so that the operative surface is adjacent the skin location. 
   While the systems described in these patents relate to therapeutic methods and apparatus for ultrasonic treatment of hard and soft tissue injuries and defects, there is a need for ergonomically configured signal generators and transducers for the treatment of cartilage and/or osteochondral injuries and/or defects. Further, a need exists for an apparatus which optimizes the treatment of cartilage and/or osteochondral injuries and/or defects. 
   A cartilage and/or osteochondral injury and/or defect typically involves damage to the cartilage which lines articulating bones (articular cartilage), such as the bones of the knee, elbow, shoulder and ankle. Osteochondral injuries can be treated by chondral and/or osteochondral drilling causing blood flow at the site. The aim of chondral drilling is to stimulate cartilage regeneration as part of the healing process. However, the resulting nonhyaline or fibrocartilage produced is biomechanically inferior to articular cartilage, does not have comparable proteoglycan content, and may consist primarily of a thin unorganized layer of collagen. Further, it has been observed that degeneration of the new tissue generally occurs over time, requiring the need for additional reconstructive surgical treatment. 
   Other methods of treatment include: the transplantation of non-weight bearing cartilage to the injury and/or defect site; inducing a fracture at the injury and/or defect site; placing a carbon fiber matrix to induce cartilage formation; and autologous chondrocyte implantation (ACI). ACI entails removing chondrocytes capable of regenerating hyaline-like cartilage from the body and culturing them for several weeks. During the culture process, the number of cells increases approximately 0.15 times that of the original tissue sample. The cultured cells are then transplanted through an arthrotomy. A small piece of periosteum, the skin covering a bone, is taken from the patient&#39;s tibia. The periosteum is then sutured over the defect to provide a protective cover for the cultured cells. The cultured cells are injected under the periosteum into the defect where they will continue to multiply and produce a durable repair tissue. However, ACI increases the healing time since the chondrocytes need to be cultured before they are transplanted to the patient. 
   Therefore, there is a further need for a method and apparatus to stimulate cartilage regeneration which produces fibrocartilage which is biomechanically equal or superior to articular cartilage, has comparable proteoglycan content, and consists of a thick organized layer of collagen. Further still, a need also exists for an apparatus which stimulates cartilage regeneration and where the regenerated cartilage does not degenerate over time requiring additional treatment or reconstructive surgery. Further, there is a need for an apparatus which stimulates cartilage regeneration and significantly reduces the healing time. 
   SUMMARY OF THE INVENTION 
   The ultrasonic treatment apparatus of the present invention is used for therapeutically treating cartilage and/or osteochondral injuries and/or defects using ultrasound. The apparatus includes an ergonomically constructed placement module configured for mounting at least one ultrasonic transducer assembly with an integral signal generator which provides excitation signals to at least one ultrasonic transducer within the transducer assembly. Timing control circuitry as well as monitoring circuitry for the proper attachment and operation of the transducer assembly are housed within a portable main operating unit which may be fit within a pouch worn by the patient. In operation, the placement module is positioned against a part of the patient&#39;s body such that at least one transducer is positioned over the cartilage and/or osteochondral injury and/or defect. At least one transducer is then excited for a predetermined period of time to impinge ultrasonic waves against the damaged cartilage area to stimulate the regeneration of new articular cartilage. 
   Preferably, the main operating unit has an internal power source for powering the signal generator circuitry, a display coupled to the signal generator circuitry to display treatment sequence data, a keypad coupled to the signal generator circuitry to permit user operation and/or entry of data. The signal generator circuitry includes a processor, means for generating a pulsed control signal, and a switch coupled to the processor for regulating the pulsed control signal. A communication interface may be connected between a communication port and the processor to provide a communication link between the ultrasonic signal generator and an external computer or modem. Preferably, the communication interface is a serial communication interface, however, a parallel interface is also contemplated. An alarm is provided to indicate to the user that the treatment time has expired. The alarm is coupled to the processor such that when ultrasonic treatment is completed the processor activates the alarm and terminates ultrasound generation. 
   The present invention also provides a kit for ultrasonically treating cartilage and/or osteochondral injuries and/or defects. The kit includes an ultrasonic transducer assembly, a placement module configured to be worn by a patient and to receive the ultrasonic transducer assembly, an integrated ultrasonic signal generator located in the ultrasonic transducer assembly, and a main operating unit (MOU) or controller. The MOU has an internal power source thereby providing patient mobility. A MOU envisioned for use with the present invention is described in U.S. Pat. No. 5,556,372 to Talish et al. which is hereby incorporated by reference. 
   The MOU is electrically coupled to at least one transducer secured to the placement module. The activation of the signal generator corresponding to each transducer excites at least one ultrasonic transducer for impinging ultrasonic waves to the cartilage and/or osteochondral injury and/or defect. 
   A method for ultrasonically treating cartilage and/or osteochondral injuries and/or defects is also provided. Once the location of the cartilage and/or osteochondral injury and/or defect is ascertained, the body&#39;s own natural healing processes are stimulated adjacent the injury. This can be accomplished by chondral drilling on the defect to form a series of channels to stimulate blood flow and induce the biological reconstructive healing response of the underlying area at the cartilage site. Other methods of stimulating this response includes laser drilling, induce fracture, scraping, chemical or biochemical treatments, etc. Once the healing response has been sufficiently facilitated, a placement module containing an ultrasonic transducer assembly having at least one transducer and one signal generator is positioned adjacent to the injured part of the body such that at least one transducer is in proximity to the cartilage and/or osteochondral injury and/or defect for the treatment of the injury. The signal generator is then activated to excite the at least one transducer for impinging ultrasonic waves to the cartilage and/or osteochondral injury and/or defect. The ultrasonic waves impinge upon the injury site to stimulate and accelerate the biological healing properties of the body to regenerate cartilaginous material. The present method can also be used in conjunction with the transplantation of autologous cultured chondrocytes to the injury site to increase the healing time. 
   In an alternative embodiment, a placement module is provided for securing a plurality of transducers thereto in a plurality of configurations. The placement module is then secured to a cartilage and/or osteochondral injury and/or defect site, for example, at the ankle or wrist, to stimulate cartilage regeneration. Further, the present invention also provides an embodiment having a placement module which contains a locking structure for locking the articulating bones in a particular position. This embodiment prevents the patient from moving his limbs, for example, moving the femur with respect to the tibia, during treatment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the drawings, which are described as follows: 
       FIG. 1  is a perspective view of a patient wearing a portable ultrasonic treatment apparatus of a first embodiment according to the present invention having a main operating unit or controller and a placement module; 
       FIG. 2A  is an exploded view of the placement module of the portable ultrasonic treatment apparatus illustrated by  FIG. 1 ; 
       FIG. 2B  is a rear underside view of the placement module of the portable ultrasonic treatment apparatus illustrated by  FIG. 1 ; 
       FIG. 3  is a cross-sectional view illustrating the transducer assembly impinging ultrasonic waves to articular cartilage within the knee where an ultrasonic conducting gel is positioned between the transducer assembly and the patient&#39;s knee; 
       FIG. 4A  is a block diagram of one embodiment of the circuitry for the ultrasonic transducer assembly; 
       FIG. 4B  is a block diagram of an alternative embodiment of the circuitry for the ultrasonic transducer assembly; 
       FIG. 5  is a perspective view of a second embodiment of the portable ultrasonic treatment apparatus, illustrating a main operating unit or controller and a placement module for treating osteochondral injuries within the elbow region; 
       FIG. 6  is a perspective view of a third embodiment of the portable ultrasonic treatment apparatus, illustrating a main operating unit or controller and a placement module for treating osteochondral injuries within the shoulder region; 
       FIG. 7  is a perspective view of a fourth embodiment of the portable ultrasonic treatment apparatus illustrating a main operating unit or controller and a placement module; 
       FIG. 8  is a perspective view of the portable ultrasonic treatment apparatus illustrated by  FIG. 7  mounted on a patient&#39;s ankle; 
       FIG. 9  is a perspective view of a fifth embodiment of the portable ultrasonic treatment apparatus, illustrating a main operating unit or controller and a placement module for treating osteochondral injuries within the knee region; 
       FIG. 10A  is an exploded view of the portable ultrasonic treatment apparatus illustrated by  FIG. 9 ; 
       FIG. 10B  is a perspective view of a support member of the portable ultrasonic treatment apparatus illustrated by  FIG. 9 ; 
       FIG. 11A  is a flow-chart depicting the steps for stimulating a healing response at the site of an osteochondral injury according to the present invention; 
       FIG. 11B  is a flow chart depicting the steps of FIG.  11 A and an additional step for monitoring the site and regulating at least one signal characteristic of the ultrasonic waves; 
       FIG. 11C  is a flow chart depicting the steps of FIG.  11 A and an additional step for changing at least one signal characteristic of the ultrasonic waves; 
       FIG. 12A  is a perspective view showing the drilling of channels within the joint walls of the femur and tibia; 
       FIG. 12B  is a cross-sectional view showing ultrasonic waves “bouncing off” the channels within the joint walls of the femur and tibia; and 
       FIGS. 13A-28B  are photomicrographs illustrating the postoperative appearance of cartilage and/or osteochondral defects created at the patellar groove region of rabbits according to studies conducted to demonstrate that daily ultrasound therapy accelerated cartilage and/or osteochondral defect healing as early as four weeks in both gross and histologic analysis. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The ultrasonic treatment apparatus of the present invention is used for the surgically non-invasive utilization of ultra high-frequency acoustic energy in the treatment of cartilage and/or osteochondral injuries and/or defects. Even though this detailed description discusses the treatment of cartilage and/or osteochondral injuries and/or defects caused by an injury, the ultrasound treatment apparatus can be used to treat osteochondral defects caused by other means, such as medication, infection or metabolic processes. 
   The apparatus includes an ergonomically constructed placement module having a strap or other fastening means for being secured adjacent an injured part of a patient&#39;s body. At least one ultrasonic transducer assembly is attached or imbedded within the placement module and properly positioned in proximity to the cartilage and/or osteochondral injury and/or defect. Different types of ultrasonic transducers and signals can be provided, such as those described and schematically depicted in U.S. Pat. No. 5,520,612 to Winder et al. which is hereby incorporated by reference. Particularly, the transducers and arrangements schematically depicted by  FIGS. 7-11  of the patent in which at least one transducer is used to provide acoustic energy to the site of the injury. The apparatus may also utilize a portable, ergonomically constructed main operating unit (MOU) worn by the patient which provides control signals to the ultrasonic transducers. The MOU which is utilized is preferably the one described in U.S. Pat. No. 5,556,372 to Talish et al. which is hereby incorporated by reference. 
   Turning to the figures, in particular  FIG. 1 , one embodiment of the portable ultrasonic treatment apparatus  10  of the present invention is shown. The ultrasonic treatment apparatus  10  includes a MOU  12 , a placement module  14 , and ultrasonic transducer assemblies  16 . 
   The placement module  14  comprises a placement support  20  which includes at least two or three channels  22  each having an extension  24  mounted therein. Each extension has a transducer pocket  26  at one end for holding one ultrasonic transducer assembly  16 . It is contemplated for each extension  24  to have several range of movements besides longitudinal motion, such as articulating motion transverse to the longitudinal motion. 
   The placement module  14  further includes a placement band  28  cooperating with slot  30  for securing the placement support  20  to the patient. The placement band  28  is configured to firmly secure the placement module  14  to the patient. A sponge-like material  32  preferably lines the inner surface of the placement support  20  for providing comfort to the patient (FIGS.  2 A and  2 B). The placement support  20  may be constructed of hard plastics which may be custom molded for a particular body part of the patient. 
   With reference to  FIGS. 2A and 2B , the extensions  24  are mounted to the placement support  20  via screws  33  and thumb screws  34 . The screws  33  are passed through slots  35  and holes  36  on the extensions  24  and are threaded to the thumb screws  34 . The extensions  24  can be moved to different positions to accommodate patients of all sizes by unthreading the thumb screws  34  and shifting the screws  33  along the slots  35  and threading the screws  33  to the thumb screws  34  at the new position. 
   The transducer assembly  16  may include circuitry, schematically illustrated by  FIGS. 4 and 4A  and described below, for exciting at least one transducer therein and is coupled to the MOU by cable  37  and wires  39 . The wires  39  are coupled to the placement support  20 . The cable  37  is preferably a multiconductor cable capable of transmitting relatively low frequency RF or optical signals, as well as digital signals. The cable  37  may include coaxial cable or other types of suitable shielded cable. Alternatively, the cable  37  may include fiber optic cable for transmitting optical signals. The signals may be transmitted continuously or as a series of pulses. 
   In operation, the placement module  14  is positioned and secured to the patient&#39;s body as shown by  FIG. 3 , such that each transducer assembly  16  lies over the cartilage and/or osteochondral injury and/or defect. A locating ring such as the one disclosed in U.S. patent application Ser. No. 08/389,148 may be used for determining the location of injured bone, if the patient desires to have one of the transducer assemblies overlying a bone injury, before the placement module  14  is secured to the patient. Once the placement module  14  is properly positioned, the transducer within the transducer assembly  16  is excited for a pre-determined amount of time. An ultrasound conducting gel  38  is positioned between the transducer assembly  16  and the injured part of the patient&#39;s body to prevent attenuation of the ultrasonic waves as they travel to the articular cartilage  40 , as shown by FIG.  3 . 
   It is also contemplated that one or more transducers can be converted to receive reflected diagnostic data from the treatment site. This permits real time evaluation of the injury site and healing process. 
   With reference to  FIG. 4A , a block diagram of one embodiment of the ultrasonic transducer assembly circuitry is shown. The transducer assembly circuitry  17  includes a receiver/RF oscillator  50  which receives the signals transferred by a signal generator within MOU  12  via cable  37 . The receiver/RF oscillator  50  is connected to transducer driver  52  which excites transducer  16 . A timing mechanism  18  is included within MOU  12  for automatically disenabling the signal generator after a predetermined period of time to terminate ultrasonic treatment. The timing mechanism  18  prevents or terminates the gating signal from reaching the RF oscillator  50  after the predetermined period of time. 
   Further, MOU  12  includes bio-feedback circuitry  19  (see  FIG. 4A ) for monitoring the condition of the cartilage and/or osteochondral injuries and/or defects and for regulating the signal characteristics according to the monitored condition. For example, if the bio-feedback circuitry determines that an osteochondral defect is severe and it therefore needs a different dose of acoustic energy to heal, MOU  12  can send a signal to the signal generator instructing the signal generator to increase, e.g., the average signal intensity of the emitted ultrasonic signals directed towards the defect. It is contemplated that the bio-feedback circuitry  19  receives signals from the transducer assembly circuitry  17  which contain reflective diagnostic data transmitted from the transducer  16  as indicated above. The bio-feedback circuitry  19  analyzes the reflective diagnostic data to determine whether to change one or more of the signal characteristics of the emitted ultrasonic waves. 
   Further still, MOU  12  includes pre-programmed treatment instructions to automatically change the signal characteristics of the emitted waves, such as the frequency, pulse repetition frequency, the pulse width, the average signal intensity and the average output power, at predetermined intervals during treatment. The pre-programmed instructions are resident within automatic signal driving circuitry (ASDC)  21 . The ASDC  21  is preferably coupled to the bio-feedback circuitry  19  and the timing mechanism  18 . 
   It is contemplated that the ASDC  21  is controlled by the bio-feedback circuitry  19  in order for the former to change at least one signal characteristic according to the monitored condition of the treatment site by the latter. However, it is further contemplated that the ASDC  21  can operate independently of the bio-feedback circuitry  19  to change at least one signal characteristic according to the pre-programmed treatment instructions. 
   An alternative embodiment of the transducer assembly circuitry  17  is shown in FIG.  4 B. In this embodiment, the ultrasonic transducer assembly  16  includes an internal battery  60  which supplies power to the components within the transducer assembly  16 . For example, battery  60  supplies power to signal monitoring circuit  62  and signal driver  66 . The signal monitoring circuit  62  provides, preferably, a digital output signal  68  which represents the waveform characteristics of the output of transducer driver  70 . These characteristics can be displayed on a digital display and may include, for example, the frequency, pulse repetition frequency, the pulse width, the average signal intensity and the average output power of the transducer  16 . The output signal  68  of signal monitoring circuit  62  is transferred to the signal generator within MOU  12  via driver  66  and cable  37 . 
   The signal generator may include a processor and a switch for regulating the signal characteristics. Alternatively, MOU  12  includes pre-programmed instructions to automatically change the signal characteristics, such as the frequency, pulse repetition frequency, the pulse width, the average signal intensity and the average output power, at predetermined intervals during treatment as discussed above with reference to FIG.  4 A. The pre-programmed instructions may be resident within a ASDC similar to the ASDC  21  of FIG.  4 A. 
   Control signals from MOU  12  are received by receiver  72  via cable  37 . Safety or fixture interlock  74 , which may include switches on the outer surface of the placement module  14  or transducer assembly  16 , ensures that the placement module  14  is properly positioned before providing power to the internal components of the transducer assembly  16 . 
   A second embodiment of the portable ultrasonic treatment apparatus of the present invention is illustrated by FIG.  5  and designated generally by reference numeral  200 . The treatment apparatus  200  includes MOU  12  and transducer assemblies  202  affixed to a placement module  204  via extensions  206  for ultrasonically stimulating the generation of cartilage in the elbow region. Each transducer assembly  202  includes a power transducer  212  connected to the MOU  12  by cable  218 . An ultrasonic conducting gel  212  is positioned between the transducer assemblies  202  and the osteochondral injury to prevent attenuation of the ultrasonic waves as they travel to the articular cartilage. In order to accommodate various patients, the extensions  206  can be adjusted to several positions by unthreading thumb screws  220 . The circuitry for each transducer assembly  202  may be similar to that disclosed for the first embodiment and schematically illustrated by  FIGS. 4 and 4A . 
   It is envisioned that the placement module  204  be constructed from suitable conductive plastics, such as conductive ABS plastics with either carbon, stainless steel, nickel or aluminum fibers to forego the use of wires for connecting the transducer assemblies  202  to the cable  218 . In such an embodiment, the conductive placement module  204  would be used to electrically connect the transducer assemblies  202  to the MOU  12  via cable  218 . 
   With reference to  FIG. 6 , a third embodiment of the portable ultrasonic treatment apparatus of the present invention is illustrated. In this embodiment, the treatment apparatus  300  includes a MOU  12 , a placement module  304 , and ultrasonic transducer assemblies  306 . The placement module  304  is configured for placement on the shoulder region and includes a placement band  310  and a placement support  312 . Each transducer assembly  306  is connected to the MOU  12  by cable  318  to power transducer assembly circuitry within each assembly  306 . The circuitry (not shown) may be similar to that disclosed for the first and second embodiments and schematically illustrated by  FIGS. 4 and 4A . 
   In operation, transducers within transducer assemblies  306  are excited for a predetermined period of time to impinge ultrasonic waves to articular cartilage within the shoulder region. 
   A fourth embodiment of the portable ultrasonic treatment apparatus of the present invention which is primarily suitable for the treatment of cartilage and/or osteochondral injuries and/or defects is illustrated by  FIGS. 7 and 8 . In this embodiment, the apparatus  400  includes at least one ultrasonic transducer assembly  402  positioned within pockets  404  on a strip  406 . The transducer assemblies  402  may be arranged in a plurality of configurations within pockets  404  to accommodate many patients&#39; anatomical differences. The strip  406  is secured in proximity to a cartilage and/or osteochondral injury and/or defect as shown by  FIG. 8  by a self-tieing material  405 . The strip  406  is connected via wires  407  and cable  408  to a MOU  12  which contains circuitry for exciting the at least one ultrasonic transducer assembly  402  affixed to the strip  406 . 
   In operation, at least one transducer assembly  402  is excited to impinge ultrasonic waves to the cartilage and/or osteochondral injury and/or defect as shown by FIG.  8 . It is contemplated that during treatment an ultrasonic conducting gel is positioned between the strip  406  and the patient&#39;s body to prevent attenuation of the ultrasonic waves. 
   It is also contemplated to manufacture the strip  406  from suitable conductive plastics such as conductive ABS plastics with either carbon, stainless steel, nickel or aluminum fibers to forego the use of wires for electrically connecting the at least one ultrasonic transducer  402  to the cable  408 . 
   A fifth embodiment of the portable ultrasonic treatment apparatus of the present invention which is primarily suitable for the treatment of cartilage and/or osteochondral injuries and/or defects is illustrated by  FIGS. 9-10B . In this embodiment, the apparatus  500  includes a MOU  12  and three ultrasonic transducer assemblies  502  positioned within pockets  504  on an inner surface of a concave plate  506  as shown by FIG.  10 B. The concave plate  506  is positioned at one end of a vertical bar  508  having a slot  509  at a lower portion. The apparatus  500  further includes a locking support module  510  having a thigh support  512  and a leg support  514 . 
   As shown by the exploded view of  FIG. 10A , the thigh support  512  includes a thigh support plate  516 , a securing band  518 , and two horizontal locking extensions  520  affixed to the thigh support plate  516  by screws  522  and thumb screws  524 . The leg support  514  includes a leg support plate  526 , a securing band  528 , and two vertical locking extensions  530  affixed to the leg support plate  526 . The vertical bar  508  is configured to mount within a channel  532  on the leg support  514 . The vertical bar  508  is secured to the channel  532  by screw  534  and thumb screw  536 . The vertical bar  508  can be moved vertically along the channel  532  by unthreading the thumb screw  536  to accommodate various patients. 
   The thigh support  512  and the leg support  514  are locked to each other by locking the horizontal locking extensions  520  and the vertical locking extensions  530  by screws  538  and thumb screws  540  to prevent the patient from moving the thigh with respect to the leg during treatment and to ensure that the transducer assemblies  502  remain fixed in their proper positions. The transducer assemblies  502  are connected via a cable  542  which is plugged in to hole  544  to the MOU  12  which contains circuitry for exciting the ultrasonic transducer assemblies  502 . It is contemplated that during treatment an ultrasonic conducting gel is positioned between the transducers  502  mounted in concave plate  506  and the patient&#39;s body to prevent attenuation of the ultrasonic waves. 
   A method for treating a cartilage and/or osteochondral injury and/or defect is depicted by the flow-chart of FIG.  11 A. The method entails stimulating blood flow to induce a biological reconstructive healing response of the underlying area at the cartilage and/or osteochondral injury site (step A), irradiating the cartilage and/or osteochondral injury site with ultrasonic waves for a time sufficient to accelerate the healing response (step B), and automatically terminating the irradiation of the ultrasonic waves after the predetermined period of time (step C). Step A entails mechanically drilling, induced fracture, laser drilling, administering chemical or biochemical treatments, scraping the injury site to stimulate the growth of cartilaginous tissue. Step B preferably entails propagating a primary directional lobe of acoustic energy in body tissue and/or fluids about a central or longitudinal axis, and this primary directional lobe is concentrically surrounded by primary shearwave lobes of acoustic energy. Step C entails automatically terminating the treatment after the predetermined period of time, e.g., via the timing mechanism  18 , to ensure adequate ultrasonic treatment. 
   During step B, the carrier frequency is sufficiently elevated to establish a standing-wave condition in one or more spaces between confronting surfaces adjacent or at the cartilage and/or osteochondral injury site, as long as the space is dimensionally characterized by at least a quarter-wavelength at the carrier frequency, thereby enabling demodulation of the carrier frequency. With reference to  FIG. 11B , the method further includes monitoring the condition of the cartilage and/or osteochondral injury site and for regulating at least one signal characteristic of the ultrasonic waves emitted by the ultrasonic transducer according to the monitored condition (step B 1 ) using bio-feedback circuitry  19  within the MOU  12  as discussed above. The bio-feedback circuitry  19  is coupled to the timing mechanism  18  and to the ASDC  21 . The ASDC  21  automatically changes at least one signal characteristic of the ultrasonic waves according to directions provided by the bio-feedback circuitry  19 . Additionally, the ASDC  21  can automatically change at least one signal characteristic of the ultrasonic waves independently as shown by step B 1  of FIG.  11 C. 
   Within a matter of days, healing proceeds at an accelerated pace in the environment of such demodulation, with resultant cartilage development in reduction of the space; but the pattern of carrier wave propagation in body tissue and/or fluids surrounding the central axis of acoustic propagation is rich in therapeutically beneficial shear waves of acoustic energy. 
   It is also contemplated to use the present method in conjunction with the transplantation of autologous cultured chondrocytes to the injury site to increase the healing time. 
   With reference to  FIGS. 12A and 12B , there are illustrated steps A and B, respectively, of  FIGS. 11A ,  11 B and  11 C.  FIG. 12A  is a perspective view showing the drilling of channels  600  within the defect using a drill  608  to stimulate blood flow and induce the biological reconstructive healing response of the underlying area at the cartilage and/or osteochondral injury site.  FIG. 12B  is a cross-sectional view showing the ultrasonic waves “bouncing off” the channels  600  within the joint walls  602  of the femur  604  and tibia  606  for a time sufficient to accelerate the healing response. 
   EXI095-01R and EXI096-01R Studies 
     FIGS. 13A-19D  are photomicrographs illustrating the postoperative appearance of cartilage and/or osteochondral defects created at the patellar groove region of rabbits according to studies (EXI095-01R and EXI096-01R) conducted to demonstrate that daily ultrasound therapy accelerated cartilage and/or osteochondral defect healing as early as four weeks in both gross and histologic analysis. Defects treated with ultrasound demonstrated more hyaline cartilage properties compared to nontreated sites at four, eight, and twelve weeks postoperative. In addition, greater subchondral bone restoration was also noted. 
   The second study, EXI096-01R, confirmed the results of the initial study, EXI095-01R, and added longer term (12 weeks) analysis. The four week postoperative ultrasound treated defects received higher gross and histologic scores compared to the nontreated defects, indicating accelerated tissue regeneration and higher levels of proteoglycan formation and cartilage like morphology and greater integration of the repair cartilage with the surrounding host cartilage. The mean gross grade for the ultrasound treated defects was 6.92/8 versus 4.83/8 for the nontreated defects at four weeks. The mean histologic grade for the ultrasound defects was 15.11/24 versus 9.28/24 for the nontreated defects at four weeks. At eight weeks postoperative, differences were more subtle both grossly and histologically between treated and nontreated defects. The mean gross grade for the ultrasound defects was 7.50/8 compared to 6.33/8 for the nontreated defects at eight weeks. The mean histologic grade for the ultrasound defects was 15.83/24 compared to 13.60/24 for the nontreated defects at eight weeks. However, at twelve weeks postoperative, dramatic differences were observed grossly between the treated and nontreated defects (7.17/8 gross grade for ultrasound defects versus 5.50/8 for nontreated defects). This may represent the initial degeneration of the inferior cartilage produced in the nontreated defects. The mean histologic grade for the ultrasound treated defects was 19.06/24. The mean grade for the nontreated defects was 15.06/24. 
   Overall, ultrasound treated sites demonstrated earlier and greater amounts of cartilage and subchondral bone regeneration. With time ultrasound sites demonstrated more extensive subchondral bone regeneration, less degeneration of adjacent cartilage, and greater chondral layer thickness and a greater amount of integration of the repair cartilage with surrounding host cartilage. These characteristics indicate a better quality of repair cartilage, that may be better able to withstand loading and degeneration over time. 
   A total of 18 male New Zealand White rabbits weighing five to nine pounds at acquisition were utilized. Specific attention was paid in selecting animals of uniform size to limit variability in loading the osteochondral defects. Bilateral 3 mm diameter by 5 mm deep osteochondral defects were created surgically in the patellar groove of each femur. Daily 20 minute ultrasound therapy was applied to the right knee defects only until sacrifice. The left defects were not treated. In an initial pilot study of six animals (EXI095-01R) three were sacrificed at four weeks postoperative and three were sacrificed at eight weeks postoperative. Each defect was evaluated grossly and histologically for the quality and extent of cartilage regeneration. Based on the four and eight week gross and four week histologic results, a second similar study was undertaken (EXI096-01R) consisting of 12 rabbits. A gross pathologic examination was made of all vital organs and systems. A summary of the surgery and treatment schedule for both studies appears in Table 1. 
   
     
       
             
           
             
             
             
             
             
           
             
           
             
             
             
             
             
           
             
           
             
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Treatment Schedule (EXI095-01R and EXI096-01R) 
             
           
        
         
             
               Animal 
               Right Knee 
               Left Knee 
                 
                 
             
             
               Number 
               Treatment 
               Treatment 
               Surgery Date 
               Duration 
             
             
                 
             
           
        
         
             
               EXI095-01R: 
             
           
        
         
             
               G200 
               20 minute daily 
               none 
               May 16, 1996 
                4 weeks 
             
             
               G203 
               20 minute daily 
               none 
               May 16, 1996 
                4 weeks 
             
             
               G217 
               20 minute daily 
               none 
               May 16, 1996 
                4 weeks 
             
             
               G198 
               20 minute daily 
               none 
               May 16, 1996 
                8 weeks 
             
             
               G201 
               20 minute daily 
               none 
               May 16, 1996 
                8 weeks 
             
             
               G202 
               20 minute daily 
               none 
               May 16, 1996 
                8 weeks 
             
           
        
         
             
               EXI096-01R: 
             
           
        
         
             
               H155 
               20 minute daily 
               none 
               Jul. 26, 1996 
                4 weeks 
             
             
               H156 
               20 minute daily 
               none 
               Jul. 26, 1996 
                4 weeks 
             
             
               H160 
               20 minute daily 
               none 
               Jul. 26, 1996 
                4 weeks 
             
             
               H152 
               20 minute daily 
               none 
               Jul. 26, 1996 
                8 weeks 
             
             
               H153 
               20 minute daily 
               none 
               Jul. 26, 1996 
                8 weeks 
             
             
               H162 
               20 minute daily 
               none 
               Jul. 26, 1996 
                8 weeks 
             
             
               H154 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
               H157 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
               H161 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
               H163 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
               H164 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
               H165 
               20 minute daily 
               none 
               Jul. 26, 1996 
               12 weeks 
             
             
                 
             
           
        
       
     
   
   The right knees received 20 minute daily ultrasound therapy with the Sonic Accelerated Fracture Healing (SAFHS) device six days weekly beginning on postoperative day four. The left knees received no treatment. SAFHS units were randomly chosen each day for treatment. Due to the large number of animals in the study EXI096-01R, some devices were used twice each day on two different animals. Animals were sedated by intramuscular injection of Ketaset and Rompun (83 mg/ml Ketamine and 17 mg/ml xylazine) at the dosage of 0.3 mg/kg body weight in order to administer the therapy. This dosage is approximately one half the anesthetic dosage intended to provide sedation only. The ultrasound transducer was placed on the distal femur at the lateral condyle with ample ultrasound coupling gel. The sites were periodically shaved to ensure contact between the transducer, coupling gel and skin. 
   The SAFHS device is a noninvasive FDA approved external device indicated for the accelerated healing of fresh fractures. SAFHS delivers a low level acoustic pressure wave signal with an intensity of 30 milliwatts per square centimeter (equivalent to the intensity used for diagnostic ultrasound) to the skin at the fracture site for twenty minutes daily. 
   Using standard aseptic techniques, surgery was performed under halothane gas anesthesia and was monitored by electrocardiogram and heart rate monitors. Anesthesia was administered by intramuscular injection of Ketaset and Rompun (83 mg/ml Ketamine and 17 mg/ml xylazine) at the dosage of 0.6 mg/kg body weight. Both hind limbs were prepped and draped in sterile fashion. The defect in the knee joint was made though a median parapatellar incision. The connective tissue securing the patella was partially released to dislocate the patella and expose the media] femoral condyle and patellar groove (FIG.  13 A). Using a drill bit, a 3 mm diameter by 5 mm deep osteochondral defect in the patellar sulcus of the femur was created (FIG.  13 B). After irrigation with saline, the joint was closed in layers (FIG.  13 C). Routine anterior-posterior radiographs were taken after surgery to insure proper defect location. 
   Butorphanol tartrate (0.2 mg/kg body weight) was administered subcutaneously as required. Animals were administered intramuscular antibiotics for four days postsurgery. Animals were kept in recovery cages postoperatively until fully conscious and demonstrated weight bearing, after which they were transferred to standard cages and allowed unrestricted motion. Halo collars were utilized as needed to prevent the animal from removing sutures. 
   Osteochondral healing was evaluated grossly and histologically. Radiographs were utilized as necessary to evaluate healing. Animals were observed daily by qualified personnel for any signs of ill health or adverse reaction to the experimental procedures. 
   Both right and left distal femurs were harvested en bloc, carefully labeled, and kept in cool saline until gross grading and microphotography was completed. The specimens were then placed in formalin based fixative and labeled with all necessary identifications. A gross pathological exam of vital organs was conducted by the in-house veterinarian. Microscopic pathologic examination was performed on any tissues determined to be grossly abnormal. 
   Each harvested defect knee was graded for gross appearance based upon the scheme of Moran et. al. ( The Journal of Bone and Joint Surgery,  74-B, 659-667, 1992) by an observer blinded to the treatment group. This analysis apportions points based upon the formation of intra-articular adhesions, restoration of articular surface, erosion and appearance of the cartilage. A total of eight points is the best possible grade (Table 2). 
   
     
       
             
           
             
             
           
             
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
               Gross Grading Scale 
             
           
        
         
             
                 
               Grades 
             
             
                 
                 
             
           
        
         
             
                 
               Intra-articular adhesions 
                 
             
             
                 
               None = 
               2 
             
             
                 
               Minimal/fine loose fibrous tissue = 
               1 
             
             
                 
               Major/dense fibrous tissue = 
               0 
             
             
                 
               Restoration of articular surface 
             
             
                 
               Complete = 
               2 
             
             
                 
               Partial = 
               1 
             
             
                 
               None = 
               0 
             
             
                 
               Erosion of cartilage 
             
             
                 
               None = 
               2 
             
             
                 
               Defect site/site border = 
               1 
             
             
                 
               Defect site and adjacent normal cartilage = 
               0 
             
             
                 
               Appearance of cartilage 
             
             
                 
               Translucent = 
               2 
             
             
                 
               Opaque = 
               1 
             
             
                 
               Discolored or irregular = 
               0 
             
             
                 
               TOTAL SCORE 
               8 possible points 
             
             
                 
                 
             
           
        
       
     
   
   All specimens were prepared for histologic evaluation. The individual specimens were fixed by immersion in either 10% formalin solution or 4% paraformaldehyde solution. Following fixation, the specimens were slowly decalcified in EDTA. The defect area was bisected across the diameter of the defect. The resulting halves and surrounding tissue were embedded in paraffin and sectioned across the defect site. Three sections, 5-7 um thick, from three levels were cut from each block. Level  1  was closest to the defect center. Level  3  was closest to the defect perimeter and level  2  was centered between levels  1  and  3 . Three sections from each level were stained with hematoxylin and eosin, Goldner&#39;s trichrome, and safranin-O and Fast Green stains (to indicate glycosaminoglycan content in the matrix). 
   Decalcified histologic sections were evaluated by an observer blinded to treatment group. Sections were graded base upon the scheme of Moran et. al. which apportion points based upon the nature of the repair cartilage, structural characteristics, and cellular changes (Table 3.) 
   
     
       
             
           
             
             
             
           
             
           
             
             
             
           
             
           
             
             
             
           
         
             
               TABLE 3 
             
             
                 
             
             
               Histology Grading Scale 
             
             
                 
             
           
           
             
               NATURE OF THE PREDOMINANT TISSUE: 
             
           
        
         
             
                 
               Cellular morphology 
                 
             
             
                 
               Hyaline articular cartilage = 
               4 
             
             
                 
               Incompletely differentiated = 
               2 
             
             
                 
               Fibrous tissue or bone = 
               0 
             
             
                 
               Safranin-O staining of the matrix 
             
             
                 
               Normal/near normal = 
               3 
             
             
                 
               Moderate = 
               2 
             
             
                 
               Slight = 
               1 
             
             
                 
               None = 
               0 
             
           
        
         
             
               STRUCTURAL CHARACTERISTICS: 
             
           
        
         
             
                 
               Surface regularity 
                 
             
             
                 
               Smooth/intact = 
               3 
             
             
                 
               Superficial horizontal lamination = 
               2 
             
             
                 
               Fissures, 25-100% of thickness = 
               1 
             
             
                 
               Severe disruption, fibrillation = 
               0 
             
             
                 
               Structural integrity 
             
             
                 
               Normal = 
               2 
             
             
                 
               Slight disruption, including cysts = 
               1 
             
             
                 
               Severe disintegration = 
               0 
             
             
                 
               Thickness 
             
             
                 
               100% of normal cartilage thickness = 
               2 
             
             
                 
               50-100% = 
               1 
             
             
                 
                0-50% = 
               0 
             
             
                 
               Bonding to the adjacent cartilage 
             
             
                 
               Bonded at both ends of the defect = 
               2 
             
             
                 
               Bonded at one end or partially bonded at both ends = 
               1 
             
             
                 
               Not bonded = 
               0 
             
           
        
         
             
               FREEDOM FROM CELLULAR 
             
             
               CHANGES OF DEGENERATION: 
             
           
        
         
             
                 
               Hypocellularity 
                 
             
             
                 
               None = 
               3 
             
             
                 
               Slight = 
               2 
             
             
                 
               Moderate = 
               1 
             
             
                 
               Severe = 
               0 
             
             
                 
               Chondrocyte clustering 
             
             
                 
               None = 
               2 
             
             
                 
               &lt;25% of cells = 
               1 
             
             
                 
               &gt;25% of cells = 
               0 
             
             
                 
               Freedom from degenerative changes in adjacent cartilage 
             
             
                 
               Normal cellularity, no clusters, normal staining = 
               3 
             
             
                 
               Normal cellularity, mild clusters, moderate staining = 
               2 
             
             
                 
               Mild or moderate hypocellularity, slight staining = 
               1 
             
             
                 
               Severe hypocellularity, poor or no staining = 
               0 
             
             
                 
                 
             
           
        
       
     
   
   Immunohistochemical staining of cartilage sections from twelve week ultrasound treated and nontreated defects was performed to identify Type I and Type II collagen. Goat antihuman polyclonals obtained from Southern Biotechnology, Inc. were used. Immunohistochemical staining identifies the critical components of articular cartilage necessary for correct regeneration and maintenance of the tissue phenotype. In addition, the presence of other tissues reflective of inappropriate tissue formation is identified. In hyaline articular cartilage Type II collagen should be localized only in the cartilage layer above the subchondral bone. Staining for Type I collagen should be restricted to the subchondral bone region. 
   All surgeries were uneventful with no postoperative complications. Pathologic examination of internal organs demonstrated no adverse response to the daily ultrasound treatment or experimental procedures. 
   A summary of the gross evaluation grades from studies EXI095-01R and EXI096-01R appears in Table 4.  FIGS. 2 through 4  demonstrate the typical gross appearance of the treated and nontreated sites at four, eight, and twelve weeks postoperative. 
   
     
       
             
           
             
             
             
           
             
             
             
             
           
         
             
               TABLE 4 
             
           
           
             
                 
             
             
               Mean Gross Evaluation Grade ± standard deviation (n = 6) 
             
           
        
         
             
                 
               NONTREATED 
               ULTRASOUND 
             
             
                 
                 
             
           
        
         
             
                 
                4 WEEKS 
               4.83 ± 1.72 
               6.92 ± 1.02 
             
             
                 
                8 WEEKS 
               6.33 ± 0.82 
               7.50 ± 0.45 
             
             
                 
               12 WEEKS 
               5.50 ± 1.22 
               7.17 ± 0.98 
             
             
                 
                 
             
           
        
       
     
   
   At four weeks postoperative, the ultrasound treated defects demonstrated more complete and uniform covering of the defect, although typically the new cartilage had an opaque appearance. Incompletely covered lesions were present at the center of many of the nontreated sites and the tissue regenerated was irregular in color (FIG.  14 ).  FIG. 14A  shows the four week postoperative gross appearance of the right knee of animal H156 after undergoing SAFHS therapy. This defect received a score of 8 out of 8 possible points.  FIG. 14B  shows the four week postoperative gross appearance of the left knee of animal H156 which was nontreated. This defect received a score of 6 out of 8 possible points.  FIG. 14C  shows the four week postoperative gross appearance of the right knee of animal G217 after undergoing SAFHS therapy. This defect received a score of 7 out of 8 possible points.  FIG. 14D  shows the four week postoperative gross appearance of the left knee of animal G217 which was nontreated. This defect received a score of 3 out of 8 possible points. 
   By eight weeks both the ultrasound and nontreated defects were covered uniformly with new tissue. The ultrasound treated defects demonstrated less erosion of the new cartilage and surrounding intact cartilage (FIG.  15 ).  FIG. 15A  shows the eight week postoperative gross appearance of the right knee of animal G201 after undergoing SAFHS therapy. This defect received a score of 7.5 out of 8 possible points.  FIG. 15B  shows the eight week postoperative gross appearance of the left knee of animal G201 which was nontreated. This defect received a score of 5 out of 8 possible points.  FIG. 15C  shows the eight week postoperative gross appearance of the right knee of animal H153 after undergoing SAFHS therapy. This defect received a score of 8 out of 8 possible points.  FIG. 15D  shows the eight week postoperative gross appearance of the left knee of animal H153 which was nontreated. This defect received a score of 7 out of 8 possible points. 
   At twelve weeks postoperative the defect borders in the ultrasound treated defects were difficult to appreciate and the new cartilage had the appearance of the adjacent tissue ( FIG. 16 ) and it was well integrated with the adjacent host cartilage. New cartilage had a more transparent appearance compared to the nontreated defects and clearly demonstrated significantly less erosion of the adjacent and newly formed cartilage.  FIG. 16A  shows the twelve week postoperative gross appearance of the right knee of animal H164 after undergoing SAFHS therapy. This defect received a score of 8 out of 8 possible points.  FIG. 16B  shows the twelve week postoperative gross appearance of the left knee of animal H164 which was nontreated. This defect received a score of 6 out of 8 possible points.  FIG. 16C  shows the twelve week postoperative gross appearance of the right knee of animal H157 after undergoing SAFHS therapy. This defect received a score of 8 out of 8 possible points.  FIG. 16D  shows the twelve week postoperative gross appearance of the left knee of animal H157 which was nontreated. This defect received a score of 3 out of 8 possible points. 
   A summary of the mean histologic grades from studies EXI095-01R and EXI096-01R appears in Table 5. One half of each twelve week specimen has been submitted for tissue typing analysis aimed at identifying the collagen type and percent tissue composition. 
   
     
       
             
           
             
             
             
             
           
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 5 
             
           
           
             
                 
             
             
               Mean Histologic Grades for the four, eight, and twelve weeks 
             
             
               postoperative sites ± standard deviation (sample size) 
             
             
               for both EXI095-01R and EXI096-01R. 
             
           
        
         
             
                 
               4 Weeks Postoperative 
               8 Weeks Postoperative 
               12 Weeks Postoperative 
             
           
        
         
             
                 
               Nontreated 
               Ultrasound 
               Nontreated 
               Ultrasound 
               Nontreated 
               Ultrasound 
             
             
                 
                 
             
           
        
         
             
               Nature of the 
               1.11 ± 1.02 
               4.06 ± 2.44 
               3.87 ± 1.77 
               3.72 ± 1.81 
               3.50 ± 2.09 
               5.61 ± 1.20 
             
             
               Predominant 
               (18) 
               (18) 
               (15) 
               (18) 
               (18) 
               (18) 
             
             
               Tissue 
             
             
               Structural 
               5.78 ± 1.86 
               6.78 ± 1.29 
               6.27 ± 1.49 
               7.28 ± 1.07 
               6.22 ± 1.99 
               7.17 ± 1.65 
             
             
               Characteristics 
               (18) 
               (18) 
               (15) 
               (18) 
               (18) 
               (18) 
             
             
               Freedom From 
               2.39 ± 1.72 
               4.28 ± 1.67 
               3.47 ± 1.73 
               4.83 ± 1.79 
               5.33 ± 2.52 
               6.28 ± 1.02 
             
             
               Cellular 
               (18) 
               (18) 
               (15) 
               (18) 
               (18) 
               (18) 
             
             
               Changes of 
             
             
               Degeneration 
             
             
               TOTAL 
               9.28 ± 3.61 
               15.11 ± 4.80  
               13.60 ± 3.68  
               15.83 ± 2.81  
               15.06 ± 6.30  
               19.06 ± 2.73  
             
             
               (out of 24 
               (18) 
               (18) 
               (15) 
               (18) 
               (18) 
               (18) 
             
             
               possible points) 
             
             
                 
             
           
        
       
     
   
     FIGS. 17 ,  18 , and  19  demonstrate the typical histologic appearance of both treated and nontreated defects at four, eight, and twelve weeks postoperative. 
   At four weeks postoperative differences between the ultrasound treated and nontreated defects were substantial. Intense safranin-O staining of the matrix, extensive chondroblast activity, and earlier subchondral bone formation in the ultrasound treated defects was in sharp contrast with the lack of activity and chondroblast phenotype present in the nontreated defects. Early degenerative changes of the nontreated defects was also evident. 
   With reference to  FIG. 17A , there is shown a low power view of an ultrasound treated defect (right knee of animal G217) at four weeks postoperative. Compared to the nontreated defects, there is a dramatic increase in safranin-O staining throughout the repair tissue indicating production of matrix proteoglycans. There is significant chondroblast activity and early evidence of columnar arrangement of chondrocytes at the defect interfaces. There has also been some restoration of subchondral bone.  FIG. 17B  shows a low power view of a nontreated defect (left knee of animal G217) at four weeks postoperative. Throughout the defect and at the defect margins there is little safranin-O stain present indicating absence of matrix proteoglycans. A thin layer of maturing fibrous tissue covers the surface of the defect. In addition, there has been little subchondral bony restoration. 
     FIG. 17C  shows a low power view of an ultrasound treated defect (right knee of animal H156) at four weeks postoperative. Similar to the right knee of animal G217, intense safranin-O staining throughout the repair tissue indicates production of matrix proteoglycans. There is significant chondroblast activity and early evidence of columnar arrangement of chondrocytes throughout the defect. The subchondral bone is almost completely restored. Although the interface between the repair and the adjacent intact cartilage has undergone some degenerative changes, the repair cartilage is well-bonded at the interface. (The large tear at the center of the defect occurred during sectioning.)  FIG. 17D  shows a low power view of a nontreated defect (left knee of animal H156) at four weeks postoperative. Similar to the left knee of animal G217, there is no safranin-O stain present indicating absence of matrix proteoglycans. A thin layer of maturing fibrous tissue covers the surface of the defect. Some subchondral bony has been restored. 
   At eight weeks the histologic results were similar to the gross results. Generally, safranin-O staining was not as intense at eight weeks postoperative in both the ultrasound treated and nontreated defects. However, subchondral bone regeneration was complete in the ultrasound treated sites and the repair cartilage showed less signs of degenerative changes. The nontreated sites showed less subchondral bone regeneration and organization of the repair tissue. 
   With reference to  FIG. 18A , there is shown a low power view of an ultrasound treated defect (right knee of animal G198) at eight weeks postoperative. Compared to the nontreated defect, the new cartilage is well-bonded to the adjacent intact cartilage. There is significant chondroblast activity and evidence of columnar arrangement of chondrocytes. The new tissue layer is thicker than the adjacent intact cartilage. Clustering of chondrocytes is minimal and limited to the interfaces.  FIG. 18B  shows a low power view of a nontreated defect (left knee of animal G198) at eight weeks postoperative. Although safranin-O staining is present within the repair tissue, degradation of the interfaces and the surface of the repair is more advanced than in the right defect. Less subchondral bone formation is apparent and columnar organization of chondrocytes is not present. 
     FIG. 18C  is a low power view of an ultrasound defect (right knee of animal H153) at eight weeks postoperative. The subchondral bone has been completely restored. However, the repair tissue is thinner than the adjacent intact cartilage and does not show evidence of proteoglycan content in the matrix. The repair is well-bonded at the defect interfaces.  FIG. 18D  is a low power view of a nontreated defect (left knee of animal H153) at eight weeks postoperative. In contrast with the right defect, the subchondral bone has not yet been completely restored. Early degeneration of the interfaces has occurred and hypocellular regions are present at the center of the defect. 
   Again at twelve weeks the ultrasound treated site had greater mean histologic scores than the nontreated defects. In most cases, subchondral bone regeneration was complete. However, the chondral layer repair tissue in ultrasound treated sites demonstrated more articular cartilage characteristics than the nontreated sites. The majority of the nontreated sites were covered with superficial layer of maturing fibrous tissue. The intensity of safranin-O stain was slight or not present in the surface repair layer of nontreated defects. Adjacent intact cartilage was hypocellular and in several cases large clusters of greater than 20 chondrocytes were present at the junction between the repair tissue and the host cartilage. Safranin-O staining was more intense in the ultrasound treated sites, however, variations within the repair cartilage of individual defects were observed. Regions of columnar arrangement of chondrocytes, near normal chondral layer thickness and safranin-O staining intensity were present in ultrasound treated defects. 
   With reference to  FIG. 19A , there is shown a low power view of an ultrasound treated defect (right knee of animal H164) at twelve weeks postoperative. Safranin-O staining intensity of the repair tissue is nearly identical to the adjacent intact cartilage. Chondrocytes within the middle layer of the repair cartilage have a columnar arrangement, are plump and actively producing proteoglycans.  FIG. 19B  shows a low power view of a nontreated defect (left knee of animal H164) at twelve weeks postoperative. In contrast with the contralateral ultrasound treated defect, there is little safranin-O staining within the repair tissue in this section. The repair cartilage thickness is approximately 50% of the adjacent intact cartilage. The chondrocytes have a random arrangement. 
     FIG. 19C  is a low power view of an ultrasound treated defect (right knee of animal H157) at twelve weeks postoperative. The repair tissue has near normal cartilage morphology, although a small area has more randomly arranged chondrocytes. The repair is well-bonded to the adjacent intact cartilage and little deterioration has occurred.  FIG. 19D  shows a low power view of a nontreated defect (left knee of animal H157) at twelve weeks postoperative. Only a superficial layer of fibrous tissue covers the subchondral bone. A large fissure through the fibrous tissue into the subchondral bone remains. There is no evidence of any active cartilage regeneration. 
   Strong Type II collagen staining of the newly regenerated cartilage layer was found in ultrasound treated defects that showed good repair, whereas nontreated defects sections with poor repair showed less intensive staining or staining of cartilage deep within the defect reflective of inappropriate tissue formation. 
   Positive staining for Type I collagen in the regenerated bone showed very little or no localization in the regenerated cartilage layer of the ultrasound treated samples. Presence of Type I collagen in the non-bone areas would be an indication of fibrosis or formation of fibrocartilage. 
   An additional study, EXI097-01R, was conducted on 66 rabbits which received bilateral osteochondral defects in the femurs according to the study design described above. A summary of the gross grading results from this study pooled with those from studies EXI095-01R and EXI096-01R are presented in “Gross Grading Results” in Table 6. 
                                                       TABLE 6                   Gross Grading Results            Treatment Group   Evaluation Period       TOTAL                    Abrasion Defects    4 weeks   Mean   5.7       20 mins. ultrasound       Std. Dev.   1.0               Sample Size   6       Control       Mean   4.8               Std. Dev.   0.8               Sample Size   6       Medial Condyle    4 weeks   Mean   4.9       Defects       Std. Dev.   1.4       20 mins. ultrasound       Sample Size   6       Control       Mean   4.8               Std. Dev.   0.6               Sample Size   6       Patellar Groove    4 weeks   Mean   5.5       Defects       Std. Dev.   1.0       20 mins. ultrasound       Sample Size   6       Control       Mean   5.8       (paired)       Std. Dev.   0.3               Sample Size   6       Patellar Groove    4 weeks   Mean   6.7       Defects       Std. Dev.   1.0       20 mins. ultrasound       Sample Size   6        5 mins. ultrasound       Mean   5.8               Std. Dev.   1.0               Sample Size   6       Patellar Groove    4 weeks       Defects       ONGOING       20 mins. ultrasound       5 mins. ultrasound       Patellar Groove    4 weeks       Defects       ONGOING       20 mins. ultrasound       10 mins. ultrasound       Patellar Groove    4 weeks       Defects       ONGOING       20 mins. ultrasound       40 mins. ultrasound       Patellar Groove    4 weeks   Mean   6.6       Defects       Std. Dev.   1.0       20 mins. ultrasound (pooled)       Sample Size   18       Control       Mean   5.3       (pooled)       Std. Dev.   1.3               Sample Size   18       Patellar Groove    4 weeks   Mean   6.6       Defects       Std. Dev.   1.0       20 mins. ultrasound       Sample Size   12       Control       Mean   5.0       (paired)       Std. Dev.   1.5               Sample Size   12       Patellar Groove    8 weeks   Mean   7.0       Defects       Std. Dev.   1.2       20 mins. ultrasound (paired)       Sample Size   11       Control       Mean   5.8       (paired)       Std. Dev.   1.4               Sample Size   11       Patellar Groove   12 weeks   Mean   6.5       Defects       Std. Dev.   1.1       20 mins. ultrasound (paired)       Sample Size   11       Control       Mean   5.6       (paired)       Std. Dev.   1.1               Sample Size   11       Patellar Groove   24 weeks       Defects       ONGOING       20 mins. ultrasound for first       12 weeks postoperative       Control       (paired)       Patellar Groove   24 weeks       Defects       ONGOING       20 mins. ultrasound for       first 18 weeks postoperative       Control       (paired)                    
Additional Studies (EXI098-03R and EXI098-04R)
 
A. EXI098-03R
 
   A total of twelve adult male New Zealand white rabbits weighing approximately 4.4 kilograms received bilateral 3 mm diameter by 5 mm deep osteochondral defects in the patellar groove of each knee. The right knees of six rabbits received 20 minute daily therapy with the standard SAFHS 30 mW/cm 2  signal intensity ultrasound device. The left knees of these rabbits received 20 minute daily therapy with a 57 mW/cm 2  signal intensity ultrasound device. In the remaining six rabbits, the right knees received 20 minute daily therapy with the 57 mW/cm 2  signal intensity ultrasound device and the left knees were untreated controls. Defect healing was evaluated at four weeks postoperative by visual gross analysis of the appearance of the repair tissue and by histologic analysis aimed at characterizing the nature of the repair tissue. 
   The results of this study did not demonstrate statistically significant improvement in the gross and histologic appearance of the repair tissue in ultrasound treated defects when compared to untreated controls. However, all ultrasound treated defects had mean gross and histologic scores greater than untreated controls. There was no statistical difference in gross or histologic appearance between the defects treated with the 30 mW/cm 2  and 57 mW/cm 2  signal intensity ultrasound devices. The ultrasound treated sites had a more normal translucent appearance grossly and histologically greater subchondral bone restoration and better incorporation of the repair tissue with the host cartilage. A summary of the surgery and treatment schedule for the EXI098-03R study appears in Table 7. 
   
     
       
             
           
             
             
             
             
             
           
         
             
               TABLE 7 
             
           
           
             
                 
             
             
               Treatment Schedule (EXI098-03R) 
             
           
        
         
             
               Animal 
               Right Knee 
               Left Knee 
                 
                 
             
             
               Number 
               Treatment 
               Treatment 
               Surgery Date 
               Duration 
             
             
                 
             
             
               J131 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J132 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J133 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J134 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J135 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J136 
               20 minute daily 
               none 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J137 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J138 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J139 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J140 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J141 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J142 
               20 minute daily 
               20 minute daily 
               Nov. 5, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
                 
             
           
        
       
     
   
   The knees received 20 minute daily ultrasound therapy with the standard 30 mW/cm 2  ultrasound device or the 57 mW/cm 2  ultrasound device signal and were treated six days weekly beginning on the postoperative day four. The ultrasound transducer was placed on the distal femur at the lateral condyle with ample ultrasound coupling gel. The sites were periodically shaved to ensure contact between the transducer, coupling gel and skin. 
   Using standard aseptic techniques, surgery was performed under isofluorance gas anesthesia and was monitored by electrocardiogram and heart rate monitors. Anesthesia was administered by intramuscular injection of Ketaset and Rompun (83 mg/ml Ketamine and 17 mg/ml xylazine) at the dosage of 0.6 mg/kg body weight. Both hind limbs were prepped and draped in sterile fashion. The defect in the knee joint was made though a median parapatellar incision. The connective tissue securing the patella was partially released to dislocate the patella and expose the media] femoral condyle and patellar groove (FIG.  13 A). Using a drill bit, a 3 mm diameter by 5 mm deep osteochondral defect in the patellar sulcus of the femur was created (FIG.  13 B). After irrigation with saline, the joint was closed in layers (FIG.  13 C). Routine anterior-posterior radiographs were taken after surgery to insure proper defect location. 
   Butorphanol tartrate (0.2 mg/kg body weight) was administered subcutaneously as required. Animals were administered intramuscular antibiotics for four days postsurgery. Animals were kept in recovery cages postoperatively until fully conscious and demonstrated weight bearing, after which they were transferred to standard cages and allowed unrestricted motion. Halo collars were utilized as needed to prevent the animal from removing sutures. 
   Osteochondral healing was evaluated grossly and histologically. Radiographs were utilized as necessary to evaluate healing. Animals were observed daily by qualified personnel for any signs of ill health or adverse reaction to the experimental procedures. 
   Both right and left distal femurs were harvested en bloc, carefully labeled, and kept in cool saline until gross grading and microphotography was completed. The specimens were then placed in formalin based fixative and labeled with all necessary identifications. 
   Each harvested defect knee was graded for gross appearance based upon the scheme of Moran et. al. ( The Journal of Bone and Joint Surgery,  74-B, 659-667, 1992) by an observer blinded to the treatment group. This analysis apportions points based upon the formation of intra-articular adhesions, restoration of articular surface, erosion and appearance of the cartilage. A total of eight points is the best possible grade (see Table 2 above). 
   All specimens were prepared for histologic evaluation. The individual specimens were fixed by immersion in either 10% formalin solution or 4% paraformaldehyde solution. Following fixation, the specimens were slowly decalcified in EDTA. The defect area was bisected across the diameter of the defect. The resulting halves and surrounding tissue were embedded in paraffin and sectioned across the defect site. Three sections, 5-7 um thick, from three levels were cut from each block. Level  1  was closest to the defect center. Level  3  was closest to the defect perimeter and level  2  was centered between levels  1  and  3 . Three sections from each level were stained with hematoxylin and eosin, Goldner&#39;s trichrome, and safranin-O and Fast Green stains to indicate glycosaminoglycan content in the matrix. 
   Histologic sections were evaluated by an observer blinded to treatment group. Sections were graded based upon the scheme of Caplan et al. (Clinical Orthopaedics and Related Research, No. 342, pp. 254-269, 1997) which apportions points based upon the nature of the repair cartilage, structural characteristics, and cellular changes. A total of 16 points is possible (see Table 3 above). 
   All surgeries were uneventful with no immediate postoperative complications. One animal (J133) died at two weeks postoperative of complications unrelated to the ultrasound therapy. Gross and histologic data from this animal were excluded from the analysis. A summary of the mean gross evaluation grades appears in Table 8. 
   
     
       
             
           
             
             
             
             
           
             
             
             
             
           
         
             
               TABLE 8 
             
           
           
             
                 
             
             
               Mean Gross Evaluation Grades ± standard deviation 
             
             
               (sample size) for EXI098-03R. 
             
           
        
         
             
                 
                 
                 
               p value 
             
             
                 
               Nontreated 
               57 mW/cm 2   
               (paired) 
             
             
                 
                 
             
           
        
         
             
               Control vs. 57 mW/cm 2   
               6.2 ± 0.8 
               6.6 ± 0.9 
               NS 
             
             
                 
               (5) 
               (5)  
             
             
               30 mW/cm 2  vs. 57 mW/cm 2   
               6.5 ± 1.0 
               6.3 ± 0.5 
               NS 
             
             
                 
               (6) 
               (6)  
             
             
               Pooled 57 mW/cm 2   
                 
               6.5 ± 0.7 
             
             
                 
                 
               (11) 
             
             
               Pooled Ultrasound 
                 
               6.5 ± 0.8 
             
             
               (30 mW/cm 2  + 57 mW/cm 2 ) 
                 
               (17) 
             
             
                 
             
           
        
       
     
   
     FIGS. 20A-21B  demonstrate the typical gross appearance of the 30 mW/cm 2  and 57 mW/cm 2  ultrasound treated and nontreated control defects at four weeks postoperative.  FIG. 20A  shows the four week postoperative gross appearance of the left untreated knee of animal J132.  FIG. 20B  shows the four week postoperative gross appearance of the right 57 mW/cm 2  ultrasound therapy treated knee of animal J132.  FIG. 21A  shows the four week postoperative gross appearance of the left 57 mW/cm 2  ultrasound therapy treated knee of animal J140.  FIG. 21B  shows the four week postoperative gross appearance of the right 30 mW/cm 2  ultrasound therapy treated knee of animal J140. 
   There were no statistically significant differences observed among the paired gross grading results, although all ultrasound treated groups had mean gross scores greater than untreated controls. Pooled comparison of all ultrasound device treated defects (6.5±0.8, n=17) and untreated control defects (6.2±0.8, n=5) did not reveal a statistically significant difference in gross scores (p=0.5175). 
   There was no marked difference in gross appearance between any group at four weeks postoperative. All defects were in the early stage of repair. At the defect borders there was little erosion of the surrounding host cartilage. The increased gross scores in ultrasound treated groups was primarily a reflection of a more translucent and normal articular cartilage appearance of the repair tissue. 
   A summary of the mean histologic grades appears in Table 9.  FIGS. 22 and 23  demonstrate the typical histologic appearance of 30 mW/cm 2  and 57 mW/cm 2  ultrasound treated and nontreated control defects at four weeks postoperative.  FIG. 22A  shows the four week postoperative histologic appearance of the left untreated knee of animal J132.  FIG. 22B  shows the four week postoperative histologic appearance of the right 57 mW/cm 2  ultrasound therapy treated knee of animal J132 (safranin-O fast green stain).  FIG. 23A  shows the four week postoperative histologic appearance of the left 57 mW/cm 2  ultrasound therapy treated knee of animal J140.  FIG. 23B  shows the four week postoperative histologic appearance of the right 30 mW/cm 2  ultrasound therapy treated knee of animal J140 (safranin-O fast green stain). 
   
     
       
             
           
             
             
             
             
           
             
           
             
             
             
             
           
         
             
               TABLE 9 
             
             
                 
             
             
               Mean Histologic Grade ± standard deviation for EXI098-03R. 
             
             
                 
             
           
           
             
               Control vs. 57 mW/cm 2  (n = 5) 
             
           
        
         
             
                 
               Control 
               57 mW/cm 2   
               p value (paired) 
             
             
                 
             
             
               Cell Morphology 
               1.2 ± 0.8 
               1.4 ± 0.5 
               NS 
             
             
               Reconstruction of 
               1.0 ± 0.7 
               1.2 ± 0.4 
               NS 
             
             
               Subchondral Bone 
             
             
               Matrix Staining 
               1.4 ± 0.9 
               1.2 ± 0.4 
               NS 
             
             
               Cartilage Defect Filling 
               0.6 ± 0.5 
               1.0 ± 0.0 
               NS 
             
             
               Surface Regularity 
               1.0 ± 0.0 
               0.8 ± 0.4 
               NS 
             
             
               Bonding 
               1.6 ± 0.5 
               1.2 ± 0.8 
               NS 
             
             
               TOTAL 
               6.8 ± 2.5 
               6.8 ± 2.2 
               NS 
             
             
               (out of 16 possible points) 
             
             
                 
             
           
        
         
             
               30 mW/cm 2  vs. 57 mW/cm 2  (n = 6) 
             
           
        
         
             
                 
               30 mW/cm 2   
               57 mW/cm 2   
               p value (paired) 
             
             
                 
             
             
               Cell Morphology 
               1.7 ± 0.8 
               1.7 ± 0.5 
               NS 
             
             
               Reconstruction of 
               1.8 ± 0.4 
               1.5 ± 0.5 
               NS 
             
             
               Subchondral Bone 
             
             
               Matrix Staining 
               1.8 ± 1.2 
               1.8 ± 0.8 
               NS 
             
             
               Cartilage Defect Filling 
               1.0 ± 0.0 
               1.0 ± 0.0 
               NS 
             
             
               Surface Regularity 
               0.8 ± 0.4 
               0.7 ± 0.5 
               NS 
             
             
               Bonding 
               1.7 ± 0.5 
               1.3 ± 0.5 
               NS 
             
             
               TOTAL 
               8.8 ± 2.6 
               8.0 ± 2.1 
               NS 
             
             
               (out of 16 possible points) 
             
             
                 
             
             
               NS = not statistically significant, p value &gt; 0.05.  
             
           
        
       
     
   
   There were no statistically significant differences observed among the total histologic scores or individual categories of the scoring in paired comparisons of group means. All ultrasound treated groups achieved greater mean histologic scores than untreated controls with 30 mW/cm 2  ultrasound treated group achieving the greatest mean score. The mean total histologic grade for pooled ultrasound treated sites (7.9±2.3, n=17) was not statistically greater than the mean grade of untreated controls (6.8±2.5, n=5) (p=0.3497). 
   Defect healing was in the early stage in all groups. Subchondral bone regeneration was more advance in ultrasound treated sites compared to control sites. In most defects the newly generated repair tissue layer appeared thicker than the adjacent host cartilage layer. Overall, the repair tissue in the ultrasound treated defects stained more intensely with safranin-O indicating a greater glycosaminoglycan content in the matrix and was better incorporated at the host cartilage interfaces. 
   This study focusing on the use of the standard SAFHS ultrasound device on full thickness osteochondral defect healing in rabbits indicates that ultrasound therapy improves the quality of repair tissue. Statistically significant improvement in both the gross and histologic appearance of the repair tissue was observed with the use of daily ultrasound therapy. The purpose of this study was to characterize the ability of ultrasound therapy to improve the repair of osteochondral defects in the rabbit model using a signal with a greater energy intensity and compare the results to that obtained with the standard ultrasound signal. 
   B. EXI098-04R 
   A total of twelve adult male New Zealand white rabbits were utilized weighing approximately 4.4 kilograms. Trephine was used to create the study model in the patellar groove of each femur. The autologous plug created by the trephine was left in place to ensure flush replacement of the graft with the host cartilage separated by an approximate 1 mm circumferential gap created by the wall thickness of the trephine. The right knees of six rabbits were treated for 20 minutes daily with the standard SAFHS 30 mW/cm 2  ultrasound device. The contralateral left knees of these rabbits received 20 minute daily therapy with a 57 mW/cm 2  signal intensity ultrasound device. In the remaining six rabbits, the right knees received 20 minute daily therapy with the 57 mW/cm 2  signal intensity ultrasound device and the left knees were untreated controls. Defect healing was evaluated at four weeks postoperative by visual gross analysis of the appearance of the repair tissue and by histologic analysis aimed at characterizing the nature of the repair tissue. Histologic sections were prepared and assigned a numeric grade based upon the structural integrity, the nature of the repair tissue and the extent of the degradation of the adjacent articular cartilage. A summary of the surgery and treatment schedule for the EXI098-03R study appears in Table 10. 
   
     
       
             
           
             
             
             
             
             
           
         
             
               TABLE 10 
             
           
           
             
                 
             
             
               Treatment Schedule (EXI098-04R) 
             
           
        
         
             
               Animal 
               Right Knee 
               Left Knee 
                 
                 
             
             
               Number 
               Treatment 
               Treatment 
               Surgery Date 
               Duration 
             
             
                 
             
             
               J112 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J150 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J151 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J152 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J153 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J154 
               20 minute daily 
               none 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (57 mW/cm 2 ) 
             
             
               J144 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J145 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J146 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J147 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J148 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
               J149 
               20 minute daily 
               20 minute daily 
               Dec. 7, 1998 
               4 weeks 
             
             
                 
               (30 mW/cm 2 ) 
               (57 mW/cm 2 ) 
             
             
                 
             
           
        
       
     
   
   The knees received 20 minute daily ultrasound therapy with the standard 30 mW/cm 2  ultrasound device or the 57 mW/cm 2  ultrasound device signal and were treated six days weekly beginning on the postoperative day four. The ultrasound transducer was placed on the distal femur at the lateral condyle with ample ultrasound coupling gel. The sites were periodically shaved to ensure contact between the transducer, coupling gel and skin. 
   Using standard aseptic techniques, surgery was performed under isofluorance gas anesthesia and was monitored by electrocardiogram and heart rate monitors. Anesthesia was administered by intramuscular injection of Ketaset and Rompun (83 mg/ml Ketamine and 17 mg/ml xylazine) at the dosage of 0.6 mg/kg body weight. After induction, anesthesia was maintained by isofluorance gas inhalation. Both hind limbs were prepped and draped in sterile fashion. The knee joints were approached through a median parapatellar incision. The connective tissue securing the patellae were partially released to dislocate the patellae and expose the medial femoral condyles and patellar groove. The surgical model utilized Smith and Nephew mosaicplasty osteochondral grafting instruments. A 3.5 mm trephine was used to create the model defects. The osteochondral plugs were left in place in order to ensure flush placement of the graft with the host cartilage (FIG.  24 ). The plugs were separated from the adjacent cartilage by the approximate 1 mm gap created by the wall thickness of the trephine. The gap extended through the subchondral bone. After irrigation with saline, the joint was closed in layers. Routine anterior-posterior radiographs were taken after surgery to ensure proper defect location. 
   Butorphanol tartrate (0.2 mg/kg body weight) was administered subcutaneously as required. Animals were administered intramuscular antibiotics for four days post-surgery. Animals were kept in recovery cages postoperatively until fully conscious and demonstrated weight bearing, after which they were transferred to standard cages and allowed unrestricted motion. Halo collars were utilized as needed to prevent the animal from removing sutures. 
   Osteochondral healing was evaluated grossly and histologically. Radiographs were utilized as necessary to evaluate healing. Animals were observed daily by qualified personnel for any signs of ill health or adverse reaction to the experimental procedures. 
   Both right and left distal femurs were harvested en bloc, carefully labeled, and kept in cool saline until gross grading and microphotography was completed. The specimens were then placed in formalin based fixative and labeled with all necessary identifications. 
   Each harvested defect knee was graded for gross appearance based upon the scheme of Moran et. al. ( The Journal of Bone and Joint Surgery,  74-B, 659-667, 1992) by an observer blinded to the treatment group. This gross analysis apportions points based upon the formation of intra-articular adhesions, restoration of articular surface, erosion of host cartilage and appearance of the repair tissue. A total of eight points is the best possible grade (see Table 2 above). In addition, the extent and quality of healing at the graft-host cartilage interface was noted. 
   All specimens were prepared for histologic evaluation. The individual specimens were fixed by immersion in either 10% formalin solution or 4% paraformaldehyde solution. Following fixation, the specimens were slowly decalcified in EDTA. The defect area was bisected across the diameter of the defect. The resulting halves and surrounding tissue were embedded in paraffin and sectioned across the defect site. Three sections, 5-7 um thick, from three levels were cut from each block. Level  1  was closest to the defect center. Level  3  was closest to the defect perimeter and level  2  was centered between levels  1  and  3 . Three sections from each level were stained with hematoxylin and eosin, Goldner&#39;s trichrome, and safranin-O and Fast Green stains to indicate glycosaminoglycan content in the matrix. 
   Histologic sections were evaluated by an observer blinded to treatment group. Sections were graded based upon the scheme of Caplan et al. (Clinical Orthopaedics and Related Research, No. 342, pp. 254-269, 1997) which apportions points based upon the nature of the repair cartilage, structural characteristics, and cellular changes. A total of 16 points is possible (see Table 3 above). 
   All surgeries were uneventful with no immediate postoperative complications. A summary of the mean gross evaluation grades appears in Table 11. 
   
     
       
             
           
             
             
             
             
           
             
             
             
             
           
         
             
               TABLE 11 
             
           
           
             
                 
             
             
               Mean Gross Evaluation Grades ± standard deviation 
             
             
               (sample size) for EXI098-04R. 
             
           
        
         
             
                 
                 
                 
               p value 
             
             
                 
               Nontreated 
               57 mW/cm 2   
               (paired) 
             
             
                 
                 
             
           
        
         
             
               Control vs. 57 mW/cm 2   
               6.8 ± 0.8 
               7.6 ± 0.9 
               NS 
             
             
                 
               (5) 
               (5) 
             
             
               30 mW/cm 2  vs. 57 mW/cm 2   
               6.9 ± 0.8 
               7.3 ± 0.4 
               NS 
             
             
                 
               (5) 
               (5) 
             
             
                 
             
           
        
       
     
   
     FIGS. 25A-26B  demonstrate the typical gross appearance of the 30 mW/cm 2  and 57 mW/cm 2  ultrasound treated and nontreated control defects at four weeks postoperative.  FIG. 25A  shows the four week postoperative gross appearance of the untreated knee of animal J152.  FIG. 25B  shows the four week postoperative gross appearance of the right 57 mW/cm 2  ultrasound therapy treated knee of animal J152.  FIG. 26A  shows the four week postoperative gross appearance of the left 57 mW/cm 2  ultrasound therapy treated knee of animal J145.  FIG. 26B  shows the four week postoperative gross appearance of the right 30 mW/cm 2  ultrasound therapy treated knee of animal J145. 
   There were no statistically significant differences observed among the total scores or individual components of the score. However, all ultrasound treated groups (30 and 57 mW/cm 2 ) had mean gross scores greater than untreated controls. It should be noted that the number of specimens in each group (5) was small which may have masked differences present. Differences among the groups were subtle at four weeks postoperative. The autologous plug/host cartilage gap was completely filled in most cases by repair tissue. The small gap size made visualization of differences among the specimens difficult. Overall the ultrasound treated sites appeared to have better filling of gap space with a more normal appearing cartilage repair tissue. 
   A summary of the mean histologic grades appears in Table 12.  FIGS. 27 and 28  demonstrate the typical histologic appearance of 30 mW/cm 2  and 57 mW/cm 2  ultrasound treated and nontreated control defects at four weeks postoperative.  FIG. 27A  shows the four week postoperative histologic appearance of the left untreated knee of animal J152.  FIG. 27B  shows the four week postoperative histologic appearance of the right 57 mW/cm 2  ultrasound therapy treated knee of animal J152 (safranin-O fast green stain).  FIG. 28A  shows the four week postoperative histologic appearance of the left 57 mW/cm 2  ultrasound therapy treated knee of animal J145.  FIG. 28B  shows the four week postoperative histologic appearance of the right 30 mW/cm 2  ultrasound therapy treated knee of animal J145 (safranin-O fast green stain). 
   
     
       
             
           
             
             
             
             
           
             
           
             
             
             
             
           
         
             
               TABLE 12 
             
             
                 
             
             
               Mean Histologic Grade ± standard deviation for EXI098-04. 
             
             
                 
             
           
           
             
               Control vs. 57 mW/cm 2  (n = 6) 
             
           
        
         
             
                 
               Control 
               57 mW/cm 2   
               p value (paired) 
             
             
                 
             
             
               Cell Morphology 
               1.7 ± 0.8 
               1.3 ± 1.0 
               NS 
             
             
               Reconstruction of 
               0.5 ± 0.5 
               1.7 ± 1.4 
               NS 
             
             
               Subchondral Bone 
             
             
               Matrix Staining 
               1.3 ± 0.8 
               1.2 ± 1.0 
               NS 
             
             
               Cartilage Defect Filling 
               0.7 ± 0.5 
               0.7 ± 0.5 
               NS 
             
             
               Surface Regularity 
               0.5 ± 0.5 
               0.3 ± 0.5 
               NS 
             
             
               Bonding 
               0.7 ± 0.5 
               1.3 ± 0.5 
               NS 
             
             
               TOTAL 
               5.3 ± 2.4 
               6.5 ± 2.1 
               NS 
             
             
               (out of 16 possible points) 
             
             
                 
             
           
        
         
             
               30 mW/cm 2  vs. 57 mW/cm 2  (n = 6) 
             
           
        
         
             
                 
               30 mW/cm 2   
               57 mW/cm 2   
               p value (paired) 
             
             
                 
             
             
               Cell Morphology 
               1.2 ± 1.2 
               1.3 ± 0.8 
               NS 
             
             
               Reconstruction of 
               1.7 ± 1.0 
               0.8 ± 0.4 
               NS 
             
             
               Subchondral Bone 
             
             
               Matrix Staining 
               1.2 ± 1.2 
               1.2 ± 1.0 
               NS 
             
             
               Cartilage Defect Filling 
               0.7 ± 0.5 
               0.7 ± 0.5 
               NS 
             
             
               Surface Regularity 
               0.5 ± 0.5 
               0.7 ± 0.5 
               NS 
             
             
               Bonding 
               1.0 ± 0.9 
               1.0 ± 0.6 
               NS 
             
             
               TOTAL 
               6.2 ± 2.6 
               5.7 ± 2.3 
               NS 
             
             
               (out of 16 possible points) 
             
             
                 
             
             
               NS = not statistically significant  
             
           
        
       
     
   
   There were no statistically significant differences observed among the total or individual components of the histologic score in paired comparisons of group means. All ultrasound treated groups achieved a greater mean total histologic score than untreated controls. A statistically significant increase in subchondral bone regeneration was almost observed (p=0.0586) when comparing 57 mW/cm 2  ultrasound treated and untreated controls in the paired test. The means total histologic grade for pooled ultrasound treated sites (6.0±2.3, n=18) was not statistically greater than untreated controls (5.3±2.4, n=6). This is most likely due to the small number of samples. 
   Differences in histologic appearance between ultrasound treated and control sites were limited to greater reconstruction of the subchondral bone and better incorporation of the new repair tissue at the host cartilage interface. All sites were in the early stages of repair. There was little difference in the amount of defect filling which was not complete or in the degree of matrix staining. 
   This study focusing on the use of the standard SAFHS ultrasound device on full thickness osteochondral defect healing in rabbits indicates that ultrasound therapy improves the quality of repair tissue. Statistically significant improvement in both the gross and histologic appearance of the repair tissue was observed with the use of daily ultrasound therapy. The purpose of this study was to characterize the ability of ultrasound therapy to improve the repair and incorporation of autologous osteochondral plugs in a rabbit model using the standard SAFHS ultrasound device as well as an ultrasound device with a signal of greater energy intensity. 
   It will be understood that various modifications can be made to the various embodiments of the present invention herein disclosed without departing from its spirit and scope. For example, various modifications may be made in the structural configuration of the placement modules and the configuration of the components used to excite the ultrasonic transducer. Therefore, the above description should not be construed as limiting the invention but merely as presenting preferred embodiments of the invention. Those skilled in the art will envision other modifications within the scope and spirit of the present invention as defined by the claims presented below.