Method for modifying the length of a ligament

A method for modifying a ligament connection between two bones by applying radio frequency energy to a portion of a ligament in a patient that functions to maintain two or more bones in a standard configuration in a species to which the patient belongs, but which are in a relationship to each other that is not medically acceptable in the patient, for a time sufficient to induce thermal shrinkage of the portion of the ligament. The method is particularly useful for skeletal-shift disorders by applying radio frequency energy to one ligament of a set of ligaments of a patient that function to align two or more bones in a standard configuration in a species to which the patient belongs but which are causing a skeletal shift in the patient because of an imbalance of ligament-induced forces in the patient for a time sufficient to induce thermal shrinkage of the portion of the ligament, thereby alleviating the skeletal shift. Patellar shift and curvature of the spine are two examples of such disorders.

BACKGROUND OF INVENTION 
1. Technical Field 
This invention is directed to the field of surgery and is specifically 
directed to use of heat, especially that resulting from the application of 
radio frequency energy, to modify the length of ligaments. 
2. Background 
Instability of joints between bones has long been recognized as a 
significant cause of disability and functional limitation in patients. For 
example, diarthrodial joints of the musculoskeletal system have varying 
degrees of intrinsic stability based on joint geometry and ligament and 
soft tissue investment. Diarthrodial joints are comprised of the 
articulation of the ends of bones and their covering of hyaline cartilage 
surrounded by a soft tissue joint capsule that maintains the constant 
contact of the cartilage surfaces. This joint capsule also maintains, 
within the joint, the synovial fluid that provides nutrition and 
lubrication of the joint surfaces. Ligaments are soft tissue condensations 
in or around the joint capsule that reinforce and hold the joint together 
while also controlling and restricting various movements of the joints. 
Ligaments, joint capsule, and connective tissue are largely comprised of 
collagen. 
When a joint between two or more bones becomes unstable, either through 
disease or traumatic injury, its soft tissue or bony structures allow for 
excessive motion of the joint surfaces relative to each other and in 
directions not normally permitted by the ligaments or capsule. Sometimes 
there is simply a malaligmnent problem, as occurs with various unnatural 
positions of vertebrae in the spin. When one surface of a joint slides out 
of position relative to the other surface, but some contact remains, 
subluxation occurs. When one surface of the joint completely disengages 
and loses contact with the opposing surface, a dislocation occurs. 
Typically, the more motion a joint normally demonstrates, the more 
inherently loose is the soft tissue surrounding the joint. This makes some 
joints more prone to instability than others. The shoulder, glenohumeral 
joint, for example, has the greatest range of motion of all peripheral 
joints. It has long been recognized as having the highest subluxation and 
dislocation rate because of its inherent laxity relative to more 
constrained "ball and socket" joints such as the hip. 
Patent applications from the laboratory of the inventors have previously 
addressed some issues relating to joint instability. See, for example, 
U.S. patent application Ser. Nos. 08/637,095 and 08/714,987 (these 
applications also provide a thorough explanation of temperature control 
and energy supply systems that can be used with the present invention). 
Instability of the shoulder can occur congenitally, developmentally, or 
traumatically and often becomes recurrent, necessitating surgical repair. 
In fact, subluxations and dislocations are a common occurrence and cause 
for a large number of orthopedic procedures each year. Symptoms include 
pain, instability, weakness and limitation of function. If the instability 
is severe and recurrent, functional incapacity and arthritis may result. 
Surgical attempts are directed toward tightening the soft tissue 
restraints that have become pathologically loose. These procedures are 
typically performed through open surgical approaches that often require 
hospitalization and prolonged rehabilitation programs. 
More recently, endoscopic endoscope (arthroscopic) techniques for achieving 
these same goals have been explored with variable success. Endoscopic 
techniques have the advantage of being performed through smaller 
incisions, and therefor are usually less painful. Such techniques are 
performed on an outpatient basis, associated with less blood loss and 
lower risk of infection and have a more cosmetically acceptable scar. 
Recovery is often faster postoperatively than using open techniques. 
However, it is often more technically demanding to advance and tighten 
capsule or ligamentous tissue arthroscopically because of the difficult 
access to pathologically loose tissue, and because it is very hard to 
determine how much tightening or advancement of the lax tissue is 
clinically necessary. In addition, fixation of advanced or tightened soft 
tissue is more difficult arthroscopically than through open surgical 
methods. 
Collagen connective tissue is ubiquitous in the human body and demonstrates 
several unique characteristics not found in other tissues. It provides the 
cohesiveness of the musculoskeletal system, the structural integrity of 
the viscera as well as the elasticity of integument. There are basically 
five types of collagen molecules, with Type I being most common in bone, 
tendon, skin and other connective tissues, and Type III is common in 
muscular and elastic tissues. 
Intermolecular cross-links provide collagen connective tissue with unique 
physical properties of high tensile strength and substantial elasticity. A 
previously recognized property of collagen is hydrothermal shrinkage of 
collagen fibers when elevated in temperature. This unique molecular 
response to temperature elevation is the result of rupture of the collagen 
stabilizing cross-links and immediate contraction of the collagen fibers 
to about one-third of their original lineal distention. Additionally, the 
caliber of the individual fibers increases greatly, over four-fold, 
without changing the structural integrity of the connective tissue. 
There has been discussion in the existing literature regarding alteration 
of collagen connective tissue in different parts of the body. One known 
technique for effective use of this knowledge of the properties of 
collagen is through the use of infrared laser energy to effect tissue 
heating. The importance in controlling the localization, timing and 
intensity of laser energy delivery is recognized as paramount in providing 
the desired soft tissue shrinkage without excessively damaging the 
surrounding non-target tissues. 
Shrinkage of collagen tissue is important in many applications. One 
application is the shoulder capsule. The capsule of the shoulder consists 
of a synovial lining and three well-defined layers of collagen. The fibers 
of the inner and outer layers extend in a coronal access from the glenoid 
to the humerus. The middle layer of the collagen extends in a sagittal 
direction, crossing the fibers of the other two layers. The relative 
thickness and degree of intermingling of collagen fibers of the three 
layers vary with different portions of the capsule. The ligamentous 
components of the capsule are represented by abrupt thickening of the 
inner layer with a significant increase in well-organized coarse collagen 
bundles in the coronal plane. 
The capsule functions as a hammock-like sling to support the humeral head. 
In pathologic states of recurrent traumatic or developmental instability 
this capsule or pouch becomes attenuated, and the capsule capacity 
increases secondary to capsule redundance. In cases of congenital or 
developmental multidirectional laxity, an altered ratio of Type I to Type 
III collagen fibers may be noted. In these shoulder capsules, a higher 
ratio of more elastic Type III collagen has been described. Shrinkage of 
capsule collagen to improve shoulder function was previously developed in 
the laboratory of the inventors. 
Additionally, there are a number of skeletal disorders associated with 
malalignment of adjacent bones that are caused by either incorrect tension 
available from a ligament or from a group of separate ligaments, resulting 
either from disease or traumatic injury. Prior investigations into methods 
of tightening the capsule of the shoulder joint, an earlier focus of 
research in the laboratory of the present inventors, has shown a need for 
more focused research and improvements in methods of treating disorders 
associated with medically incorrect (under disease or post-traumatic 
conditions) ligament tension. The need for such further developments has 
led to the present invention. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a 
technique for straightening malaligned bones. 
It is another object of the present invention to provide a method for 
adjusting the length of a ligament graft. 
It is still another object of the present invention to provide a method of 
adjusting tension in a natural ligament. 
It is a further object of the present invention to provide treatments for 
patellar shift and spinal column malalignment. 
These and other objects of the invention have been accomplished by 
providing a method for modifying a ligament connection between two bones 
by heat energy to a portion of a ligament in a patient that functions to 
maintain two or more bones in a standard configuration in a species to 
which the patient belongs, but which are in a relationship to each other 
that is not medically acceptable in the patient, for a time sufficient to 
induce thermal shrinkage of the portion of the ligament. 
The method can be applied to skeletal-shift disorders by applying heat 
energy to one ligament of a set of ligaments of a patient that function to 
align two or more bones in a standard configuration in a species to which 
the patient belongs, but which are causing a skeletal shift in the patient 
because of an imbalance of ligament-induced forces in the patient, for a 
time sufficient to induce thermal shrinkage of the portion of the 
ligament, thereby alleviating the skeletal shift. Patellar shift and 
curvature of the spine are two examples of such disorders. 
Radio frequency (RF) energy is particularly preferred as a heat source, 
although other energy sources can be used.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS. 
The present invention is directed to a method for tightening a ligament 
connection between two bones by applying heat, preferably but not 
necessarily resulting from application of radio frequency energy, to a 
portion of a ligament in a patient that functions to maintain two or more 
bones in a standard configuration in a species to which the patient 
belongs, but which are in a relationship to each other that is not 
medically acceptable in the patient, for a time sufficient to induce 
thermal shrinkage of the portion of the ligament. The initial heating of 
the collagen in the ligament causes a contraction of the ligament (if it 
is not subject to stretching forces), but the ligament is weaker than it 
was prior to heat treatment and cam be stretched under tension to a length 
greater than it had previously. On the other hand, maintaining tension in 
the ligament less than that necessary to stretch the portion of the 
ligament subjected to thermal shrinkage until the portion has regained 
sufficient strength to maintain the bones in the standard configuration 
results in shortening of the ligament. Many different disorders of 
ligaments and injuries can be treated by shortening one or more ligaments 
using the method of the invention. 
Examples of medical conditions that can be treated include cases in which 
the ligament being treated is a surgical graft ligament and the thermal 
shrinkage is applied to adjusting the length of the ligament after 
attachment of the graft ligament to the bones. In other cases, a natural 
ligament is being shortened as in straightening curvature of the spine or 
modifying ligament tensions to correct patellar shift. 
The invention is particularly useful when used in arthroscopic 
applications, since it is often difficult in such situations to accurately 
incise or trim ligaments, and in the adjustment of graft length, since 
initial creation of a graft having the exact length necessary to achieve a 
desired function is difficult. In most such cases, an insulated probe 
having an electrode in a distal portion thereof is introduced into a body 
cavity adjacent the ligament being treated and RF energy sufficient to 
shrink collagen is applied to the ligament through the electrode. Certain 
advantages are present when energy is applied to the ligament by two 
electrodes positioned on opposite sides of the ligament rather than by 
simply heating the tendon by use of an electrode applied to one side of 
the ligament, whether the electrode is monopolar or bipolar. Such probes 
are described in a patent application filed on the same day as the present 
specification from the laboratory of the present inventors (Attorney 
Docket No. ORAT-011/00US entitled "Method and Apparatus for the Treatment 
of Strabismus") and directed specifically to the treatment of strabismus, 
a disorder that can be alleviated by the adjustment of the length of 
extraocular tendons. Probes of a similar shape but sized to engage a 
ligament, with different probes being prepared and sized for different 
ligaments (depending on the intended end use), can be used in the practice 
of the present invention. 
Situations involving desired shortening of the ligament require that the 
tension on the ligament be maintained below that necessary to stretch the 
portion of the ligament until sufficient time has elapsed to allow the 
ligament to regain its strength. The desired time can best be judged 
empirically by a physician familiar with the stresses likely to be placed 
on the ligament by the patient. For example, the stress likely to be 
encountered by the anterior cruciate ligament of a knee of a professional 
football player will be greater than the stress likely to be encountered 
by an office worker, which may require different recovery regimens for the 
two patients. Different times of stress relief for different patients is 
therefor required, as may different techniques (for example, required by 
the weight of the patient or the location of the ligament). In some cases 
tension can be relieved by tension-relieving sutures in the ligament 
itself, which can optionally be selected to dissolve in the body so that 
further surgery is avoided. In other cases, it will be appropriate to 
maintain the tension below that necessary to stretch the portion of the 
ligament by maintaining the bones in a low-tension substantially fixed 
position, such as by protecting the treated joint of a patient with a 
cast, sling, or crutches or similar device. 
One regimen would be to protect the joint from stress for 10 days, after 
which the surgeon would evaluate the range and ease of motion. If the 
joint were too loose, it would be protected longer (perhaps another 10 
days--up to 6 weeks total). If the joint were too tight, stretching 
rehabilitation aimed at obtaining normal function would be undertaken. 
Physician monitoring of the patient, with rest or stress relief once the 
proper length is attained, is the best way to improve the proper 
lengthening of a ligament, since each patient will provide a different 
activity, body weight, and temperament to be taken into consideration in 
the prescription of appropriate stress and later rest. 
The method of the invention can be combined with other medical techniques 
designed to alleviate the condition being treated, such as by releasing 
tension on the ligament being treated by a surgical incision in a ligament 
not being treated, as well as other techniques known for adjusting 
ligament placement or tension. 
The method of the invention is particularly useful for treating 
ligament-induced skeletal shift, such as patellar shift or curvature of 
the spine, that involve two or more ligaments attached to different parts 
of the same bones of a bone joint, such as the knee or spinal column. In 
such cases radio frequency energy (or another energy source) is applied to 
a portion of one ligament of a set of ligaments of a patient. The ligament 
set functions to align two or more bones in a standard configuration in a 
species to which the patient belongs, but are causing a skeletal shift in 
the patient because of an imbalance of ligament-induced forces in the 
patient resulting from disease or injury. Although most patients being 
treated by this method are expected to be human, veterinary use is also 
possible. Energy is applied for a time sufficient to induce thermal 
shrinkage of the portion of the ligament, thereby alleviating the skeletal 
shift. "Shrinkage" here (and elsewhere in this specification) refers to 
the initial collagen shrinking process and the initial resulting 
shortening (unless otherwise is clear from the context of the word), since 
final length of the ligament is the result of the initial shrinkage 
combined with growth of collagen into the affected area, and tension or 
lack of tension on the ligament. Preferred treatments are for patellar 
shift, where the ligament being treated is a medial ligament being 
shortened, and malalignment of the spinal column, where the ligament is 
one of a pair of ligaments on opposite sides of the spinal column. 
Turning now to techniques and apparatuses that can be used in the present 
invention, reference is made to the numerous patents and applications that 
exist involving the shrinkage of collagen in vivo, including the following 
from the laboratory of the present inventors: U.S. Pat. No. 5,458,596; 
U.S. Pat. No. 5,569,242; and U.S. applications Ser. Nos. 08/637,095, 
08/714,987, 08/320,304, 08/547,510, 08/390,873, 08/616,752, 08/696,051, 
08/700,195, 60/029,600, 60/029,602, 60/029,734, and 60/029,735. Other 
patents of interest include U.S. Pat. Nos. 4,976,709; 4,326,529; and 
4,381,007. All of these patents and applications describe apparatuses, 
power supplies, surgical procedures, or other components of systems that 
can be adapted to the practice of the present invention when following the 
guidance provided in the current specification. As an example of some of 
the components that can be used in the practice of the present invention, 
the following description is given of previously developed components from 
the laboratory of the inventors that can be adapted to the practice of the 
present invention. 
Referring now to FIG. 1, an apparatus for shrinking collagen containing 
ligament to a desired level is generally denoted as 10. Apparatus 10 
includes a handpiece 12 that is preferably made of a thermal insulating 
material. Types of such insulating materials are well known to those 
skilled in the art. An energy delivery device (e.g., RF electrode) 14 is 
coupled to handle 12 at a proximal end 16 of energy delivery device 14 and 
may be permanently or impermanently attached thereto. A distal end 18 of 
energy delivery device 14 includes a distal portion 20 which may have a 
geometry that delivers a controlled amount of energy to tissues in order 
to achieve a desired level of contraction of collagen fibers in a collagen 
containing ligament. Located at distal portion 20 is one or more sensors 
22 which provide a signal whose magnitude is representative of the amount 
of thermal energy sensed. 
As shown in FIG. 2, energy is supplied from an energy source 72 through a 
cable 26 to energy delivery device 14 at the end of probe neck 24 attached 
to handle 12. Since several types of energy can cause an elevation in the 
temperature of a collagen containing ligament 28, energy source 72 can 
include but is not limited to RF, microwave, ultrasonic, coherent and 
incoherent light, thermal transfer, and resistance heating. Return cable 
50 from a sensor (not shown) provides feedback control through signal 
processing by microprocessor 74. 
As illustrated in FIG. 3, distal portion 20 of the probe contains the 
electrode that is positioned during operation adjacent to a collagen 
containing ligament 28 which is at least partially adjacent to a fluid 
medium 30. Appropriate collagen containing ligaments 28 for the purpose of 
the present invention includes ligaments. Distal portion 20 is preferably 
in contact with collagen containing ligament 28. Fluid medium (usually 
sterile saline) 30 may be flowing as would result from irrigating collagen 
containing ligament 28, or it may be substantially less dynamic or 
non-moving. During the procedure, the fluid medium 30 also contains pieces 
of bone, ligament blood and other tissue. Energy is delivered from distal 
portion 20 to a selected site 32 of the collagen containing ligament 28. 
Selected site 32 receives at least a portion of the delivered energy. Once 
the energy is delivered, it becomes thermal energy, causing the thermal 
energy content and the temperature of selected site 32 to increase. As the 
thermal energy content of selected site 32 is increased, thermal energy is 
conducted to the collagen fibers in and around selected site 32. Collagen 
fibers exposed to sufficient thermal energy lose their triple helix shape. 
Since the triple helix shape of collagen fibers is the longest shape for 
collagen fibers, fibers which lose their triple helix shape will contract. 
Thus, the delivery of energy to selected site 32 causes the temperature 
and the thermal energy content of selected site 32 to increase and effects 
collagen fiber contractions. The collagen fiber contraction results in a 
contraction of collagen containing ligament 28. 
Energy delivery device 14 is configured to deliver a desired level of 
energy to selected site 32. Sensor 22 (an internal sensor in this 
embodiment) provides a signal indicative of a composite temperature of at 
least selected site 32 and at least a portion of adjacent fluid medium 30 
to a feedback control unit. The signal is received by a feedback control 
system which adjusts the level of energy supplied to energy delivery 
device 14 and delivered to selected site 32 based on the signal received 
from sensor 22. 
Throughout the treatment, it is often desirable to effect contractions in a 
selected area 34 which is larger than a selected site 32, such as they are 
extending from 34a to 34b in FIG. 3. Further, it may be desirable to 
elevate the temperature of the selected site 32 or selected area 34 to a 
desired average temperature for a specified period of time. There are 
several methods available for achieving these results. For instance, one 
embodiment is to "paint" distal portion 20 across selected area 34 by 
continually moving distal portion 20 over the surface of the selected area 
34 so that the entire selected area 34 is covered. Selected area 34 can 
then be brought to the desired temperature and retained at that 
temperature by continually moving distal portion 20 over selected area 34. 
In another embodiment, distal portion 20 is left at selected site 32 until 
the desired temperature is obtained for the desired time. Distal portion 
20 is then moved to another selected site 32 for a desired time. This 
pattern is repeated until the entire selected area 34 is covered. A 
combination of these techniques may also be used. 
The composite temperature read by a temperature sensor at the site of heat 
treatment is a combination of at least two different temperatures in some 
ratio. One temperature 25 is from at least a portion of adjacent fluid 
medium 30 and another temperature 27 of at least a portion of selected 
tissue site 32. This ratio is a function of different parameters including 
but not limited to the size, shape, dimensions and geometry of a thermal 
energy delivery surface of energy delivery device 72, the portion of the 
thermal energy delivery surface that is in contact with adjacent fluid 
medium 30 and selected tissue site 32, and the location of sensor 22 in 
relationship to the thermal energy delivery surface. Current flow 29, 
which creates molecular friction, and conducted thermal energy are greater 
in selected tissue site 32 because the probe is pressed into the site and 
the dipole is on the opposite side of this side and the constant entry of 
room temperature saline into the operating field maintains the fluid 
temperature at 20.degree. C. than in adjacent fluid medium 30 due to the 
higher resistance of the tissue. At the thermal 
energy-delivery-device/fluid-medium interface there is less resistance 
than at the tissue interface and a hydrodynamic force, which contribute to 
a lower reflected temperature. At the tissue interface there is a static 
conductive situation with a higher resistance producing higher reflective 
temperature at the interface. 
In the embodiment of distal portion 20 illustrated in FIG. 3, distal 
portion 20 includes sensor 22 positioned in an interior of distal portion 
20. A thermally conductive material 31 at least partially surrounds sensor 
22 and a potting compound 33 is included. Distal end 18 is made of 
stainless steel, and a nylon coating 35 insulates that part of the 
exterior surface of distal portion 20 that does not function as an 
electrode. 
The apparatus 10 in the embodiment shown in FIGS. 1-3, delivers monopolar 
RF power through the distal portion 20 to ground pad 80 See FIG. 3!. As 
will be obvious to those skilled in the art, the apparatus can be 
configured to deliver RF energy in a bipolar arrangement. The electrode or 
other device 14 used to deliver energy can be made of a number of 
different materials including but not limited to stainless steel, 
platinum, other noble metals, and the like. The electrode can also be made 
of a memory metal, such as nickel titanium, commercially available from 
Raychem Corporation, Menlo Park, Calif. The electrode can also be of 
composite construction whereby different sections are constructed from 
different materials. Electrodes formed to deliver energy directionally, as 
described in an application from the laboratory of the present inventors 
filed the same day as the present application (attorney docket No. 
ORAT-013/00US and entitled "Electrode for Electrosurgical Ablation of 
Tissue") can also be used in the practice of the present invention. 
Feedback control systems can be used to obtain the desired degree of 
contraction by maintaining selected site 32 at a desired temperature for a 
desired time. It has been shown that temperatures of 45 to 90.degree. C. 
can cause collagen fiber contractions. It has also been shown that the 
degree of collagen fiber contraction is controlled by how long the 
temperature is elevated as well as how high it is elevated. Thus, the same 
degree of contraction can be obtained by exposing selected site 32 to a 
high temperature for a short period of time or by exposing selected site 
32 to a lower temperature for a longer period of time. A preferred range 
for desired temperatures is about 45 to 75.degree. C.; still a more 
preferred range is 45 to 65.degree. C.. Before treatment, the surgeon 
evaluates the characteristics of the selected site 32 to determine what 
degree of contraction is necessary and also whether it is appropriate to 
treat the selected site 32 with a high temperature for a low period of 
time or lower temperature for a long period of time. The surgeon then 
controls the temperature either manually or through a system with feedback 
and automatic control. 
Sensor 22 can consist of, but is not limited to, a thermocouple, a 
thermistor, or phosphor-coated optical fibers. The sensor 22 can be in an 
interior of the distal portion 20 or on the surface of the distal portion 
20 and can further be a single sensor 22 or several sensors. It can also 
be a band or patch instead of a sensor 22 which senses only discrete 
points. 
Sensor 22 provides a signal whose magnitude is representative of the 
thermal energy content of the surfaces and mediums in physical contact 
with the surface of the sensor 22. Thus, if several surfaces or mediums 
are in physical contact with sensor 22, the magnitude of the signal 
provided by sensor 22 will be representative of a composite of the thermal 
energy contents of those surfaces and/or mediums. Further, the effective 
surface of sensor 22 can be increased by wholly enclosing sensor 22 in a 
medium which easily conducts thermal energy. In this embodiment, thermal 
energy will be conducted from the surface of the thermally conductive 
medium to the sensor 22. The magnitude of the signal will represent a 
composite of the thermal energy contents of any surfaces and mediums in 
physical contact with the surface of the thermally conductive medium. 
Apparatus 10, comprising handpiece 12 and distal portion 20 with an 
electrode or other energy delivery device, is adapted to be introduced 
through an operating cannula for percutaneous applications. It will be 
appreciated that apparatus 10 may be used in non-percutaneous applications 
and that an operating cannula is not necessary in the broad application of 
the invention. 
Distal portion 20 of a probe generally includes an insulating layer 35 
which is substantially impenetrable to the energy delivered to collagen 
containing ligament 28. Specifically, in the case of an RF electrode, 
electrical insulation can be used. Insulation 35 can be formed on the 
probe such that a minimum of energy is delivered to tissue, organs or 
other bodies which the surgeon does not wish to treat. For example, when 
an electrode is introduced into a tight area, and only one surface of the 
tight area is to be treated, it is desirable to avoid delivering energy 
outside of that surface. The inclusion of insulating layer 35 accomplishes 
this result. Suitable insulation materials include but are not limited to 
nylon, teflon, polyamide, epoxy varnish, PVC and the like. 
The area of the energy delivery device (e.g., electrode) that serves as a 
conductive surface can be adjusted by the inclusion of an insulating 
sleeve that is positioned around the energy delivery device. The sleeve 
may be advanced and retracted along the surface of the energy delivery 
device in order to increase or decrease the surface area of conductive 
surface that is directed to collagen containing ligament 28. The sleeve 
can be made of a variety of materials including but not limited to nylon, 
polyamides, other thermoplastics and the like. The amount of available 
conductive surface available to deliver thermal energy can be achieved 
with devices other than a sleeve, including but not limited to printed 
circuitry with multiple circuits that can be individually activated, and 
the like. 
The surgeon determines which collagen containing ligament 28 requires 
contraction and how much shrinkage should occur. The surgeon then selects 
an area of the collagen containing ligament 28 for shrinkage. The surgeon 
can find the selected area 34 by using arthroscopic viewing or using the 
apparatus 10 including a viewing scope. Once the surgeon places the energy 
delivery device next to the selected site 32, the surgeon soon begins 
delivery of energy. 
Current and voltage are used to calculate impedance. An operator-set level 
of power and/or temperature may be determined, and this level can be 
maintained manually or automatically if desired. The amount of RF energy 
delivered controls the amount of power. Feedback can be the measurement of 
impedance or temperature and occurs either at controller or at RF source 
if it incorporates a controller. Impedance measurement can be achieved by 
supplying a small amount of non-therapeutic RF energy. Voltage and current 
are then measured to confirm electrical contact. 
Circuitry, software and feedback to a controller result in full process 
control and are used to change (i) power (modulate)--including RF, 
incoherent light, microwave, ultrasound and the like, (ii) the duty cycle 
(on-off and wattage), (iii) monopolar or bipolar energy delivery, (iv) 
fluid (electrolytic solution delivery, flow rate and pressure and (v) 
determine when ablation is completed through time, temperature and/or 
impedance. 
A monopolar electrode is a part of a circuit that includes the RF signal 
generator, connecting cables, probe tip for insertion into a joint space 
(or other fluid-filled bodily cavity), the patient's body, an indifferent 
or grounding electrode attached to the patient's body at a remote site and 
the return cable that connects the grounding electrode to the RF generator 
completing the circuit. Because such an RF electrode is a relatively good 
conductor, the electrode itself does not heat up. The tissues that the 
electrode comes in contact with, heat up in response to current passing 
from the electrode through the tissues. The tissue heats up because it is 
a relatively poor conductor as compared to the rest of the circuit. It is 
when the tissues heat up as a result of molecular friction, that heat is 
then conducted back to the electrode itself. At that point, a thermocouple 
(TC) within the electrode tip, senses the increase in temperature and 
supplies that information to the RF generator so that the feedback 
mechanism can attenuate the energy delivered in order to attain 
temperature control. It is this feature (electrode does not heat) that 
makes RF advantageous over other forms of heating because the electrode 
cools immediately after use. 
A monopolar electrode has multiple surfaces which may be in contact with 
tissue at only a small percentage of the surface of the electrode. The 
rest of the electrode is exposed to the fluid-filled medium (typically 
normal saline) of the arthroscopically instrumented joint space. This 
fluid is most often not heated and may even be much colder than the nodal 
body temperature (typically between 18.degree. and 25.degree. C.). 
Therefore, the temperatures the electrode is exposed to may be 25.degree. 
C. over 70% of the electrode surface, and 65.degree. C. at the surface of 
the electrode that is in contact with the target tissues. 
A thermocouple embedded within a solid electrode would therefore read a 
composite temperature, for simplicity's sake, 70%--25.degree. C. and 
30%--65.degree. C., whereas the temperature that is important to monitor 
is the 30%--65.degree. C. alone. Some electrode configurations have been 
investigated that minimized the amount of exposure to the cold fluid 
medium. However, it was found that it is desirable to have an electrode 
that the operator can use on all surfaces to include the distal 
cross-sectional tip and the circumferential lateral aspects of the 
electrode side walls. Therefore, the electrode needs to be able to sense 
the highest temperatures at the tissue/electrode interface with minimal 
influence from the colder fluid medium. 
This is accomplished by providing a hollow electrode, within which the 
thermocouple is located. This hollow compartment is filled with a heat 
sink paste and is potted (sealed) at the distal end to contain the heat 
sink paste within this compartment. It is this heat sink paste that 
conducts the elevated temperature within the confines of the hollow 
compartment that provides for the transmission of conducted heat from the 
hotter electrode zones. Since thermal energy is a relative, dynamic state, 
the higher temperatures of the tissue-interface electrode zones are 
preferentially transmitted within the heat sink compartment, improving the 
sensing of the target temperature. 
In addition to monopolar electrodes, bipolar electrodes can also be used in 
the practice of the invention. Such electrodes provide both electrodes 
necessary to complete the circuit on the same handpiece, usually at the 
tip of the probe. No further electrode for completion of the circuit is 
required. 
In some uses of electrosurgical devices, the power electrode is moved soon 
after the target temperature is attained since coagulation of the tissues 
is accomplished fairly quickly. As the electrode is moved it encounters 
cooled or nonheated tissue. That non-heated tissue initially cools the 
electrode until molecular friction again heats the tissue. The heating of 
the new tissue, (and in turn heating the electrode) becomes a continuous 
process as the electrode is moved and a new electrode/tissues interface is 
established at each point along the path of the electrode's movement. 
As may not be apparent from the discussion so far, the fluid in the joint 
space is in constant motion. Often these irrigating fluids flow through 
the joint by means of a series of in-flow and out-flow cannulas connected 
to a pump. The effect is that there is a convection of heat away from the 
electrode surface which is exposed to the fluid medium and not in contact 
with the tissue. 
Applications from the laboratory of the inventors have previously described 
other methods of capturing target temperatures within a dynamic, coot 
fluid environment. They include the concave electrodes ("red blood cell 
shaped") with fenestrated concavities containing a thermocouple so that 
when the rim of the electrode is in contact with the tissues to be heated, 
a small amount of fluid is trapped within the concavity which heats in 
response to the tissues heating. This thermal energy then is sensed by the 
TC which may not be in contact with the target tissue, by the conduction 
of energy through the fluid. These can be both monopolar or bipolar; two 
sided or one sided. 
EXAMPLE 
The present invention can be illustrated by consideration of methods for 
treatment of dislocation of the kneecap (patellar shift). Release of the 
patella can be accomplished with the use of thermal energy applied to the 
patellar ligaments to shorten or lengthen the side ligaments. For this 
operation to be performed arthroscopically, the knee joint is distended 
with a clear fluid, usually physiological saline. Initial distention can 
be done using a large syringe to inject saline into the joint space. 
Distention forces the bones of the joint apart, creating room to introduce 
instrumentation without damaging the cartilage. 
Once the instrumentation has been inserted into the joint space, irrigation 
tubing and cannulas are positioned and hooked up to provide continual 
fluid exchange during the procedure. The most common systems are gravity 
flow or the use of an arthroscopic irrigation pump. Hanging bags of 
irrigation fluid on an IV pole raises them 3-4 feet above the operative 
site. This elevation creates enough pressure to distend and irrigate the 
joint. The fluid enters the joint through the sheath of the arthroscope 
and exits through a cannula placed in the superior lateral portal, or the 
reverse, through the cannula and out through the scope sheath. The exact 
setup is a matter of physician preference. The key to the proper function 
of any system is that the inflow volume must be equal to or slightly 
larger than the outflow volume. This restriction in the outflow creates 
the internal pressure that distends the joint. 
With an arthroscopic irrigation pump, the bags do not need to be raised on 
an IV pole. The factors controlling distention of the joint are controlled 
automatically by the pump. The pump monitors the fluid pressure in the 
joint space using a pressure-sensing cannula and automatically increases 
or decreases fluid flow as needed to provide optimum viewing. As with the 
gravity flow system, fluid enters the joint cavity through the scope 
sheath or the cannula in the superior lateral portal. 
Such an arthroscopic procedure requires the creation of two to five portals 
(entryways) into the joint capsule. To create a portal, the surgeon 
usually begins by making a small stab wound with a scalpel (e.g., No. 11 
blade) at the desired site of the portal. Next, the wound is enlarged and 
extended with a trocar encased in a sleeve (cannula) through muscle tissue 
to the synovial membrane. The trocar is removed, leaving the cannula in 
place. Then the surgeon uses a blunt obturator (to avoid damage to menisci 
and articular cartilage) to puncture through the synovium into the joint 
cavity. 
The obturator is removed and the cannula left in place. The cannula can be 
used to insert an arthroscope or for the inflow and outflow of irrigation 
fluid. If the surgeon elects to insert instruments percutaneously, the 
sleeve is removed. 
For patellar release, the surgeon frequently will use three portals, one 
for the arthroscope, one for the instrument, and one for the drain. 
Additional portals may be created for the surgeon to access other areas of 
the knee (i.e., to tighten the medial retinaculum) during the procedure. 
Frequently, a superolateral (above and to the side of the patella) 
approach is used for the irrigation cannula. For the arthroscope and 
electrosurgical probe, anteromedial and anterolateral approaches often are 
chosen, because they are relatively safe (minimal potential tissue damage) 
and most surgeons have more experience with them. 
Using the surgical setup as described, RF energy is applied to the lateral 
or medial ligament to adjust the length of the ligaments (and thus tension 
con and positioning of the patella). Since most cases of dislocation of 
the patella involve lateral movement of the patella (to the outside of the 
knee), ligaments on the medial side of the patella are shortened, while 
lateral ligaments are lengthened (if appropriate for the particular 
surgical operation being performed). In a typical operation, RF energy is 
applied to the medial ligament to shorten that side of the attachment 
without lengthening the lateral ligament (to avoid loosening the patellar 
placement). The degree of shortening should be determined by the physician 
depending on the condition of the individual being treated and the 
specific condition of that individual's dislocation. Depending on the 
stress to which the knee will likely be subjected, rest or immobilization 
can be prescribed for a time sufficient to allow new collagen to penetrate 
and strengthen the shrunken region of the ligament. Reduction of tension 
on the treated ligament for about 6 weeks is sufficient for many cases. 
All publications and patent applications mentioned in this specification 
are herein incorporated by reference to the same extent as if each 
individual publication or patent application was specifically and 
individually indicated to be incorporated by reference. 
The invention now being fully described, it will be apparent to one of 
ordinary skill in the art that many changes and modifications can be made 
thereto without departing from the spirit or scope of the appended claims.