Abstract:
A surgical instrument includes a clamp having a handle with a pair of substantially parallel prongs or tines extending from the handle, all formed as a unitary body or article of manufacture. The handle and prongs define a channel to receive a knife. The knife includes a handle, a scalpel, and an extension arm coupling the scalpel to the handle. The clamp defines a minor image about a central axis. In this way, the surgeon need not concern himself with whether the knife is oriented properly within the channel. Also, the extension arm of the knife includes graduations to assist the surgeon in predetermining precisely the distance of cut in using the instrument. The upper prong of the clamp includes a downwardly extending capture pad having a bottom surface substantially parallel to the inner surface of the lower prong. The upper and lower prongs define a mouth, having a continuously increasing distance between upper and lower prongs so that the clamp is guided onto the tissue target of choice in a non-invasive manner.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 10/419,590, filed Apr. 21, 2003 and entitled “MINIMALLY INVASIVE TECHNIQUE FOR PERFORMING PLANTAR FASCIOTOMIES AND SURGICAL INSTRUMENTS FOR USE IN SUCH A TECHNIQUE.”, which is abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of surgical instruments, and, more particularly, to a technique and a surgical instrument for performing plantar fasciotomies. 
     BACKGROUND OF THE INVENTION 
     Chronic heel pain is one of the most common types of pain affecting the human body. It is estimated that over six million people in the United States develop this condition every year. Traditional treatments for such chronic heel pain include cortisone injections, oral anti-inflammatory medications, shoe inserts, and physical therapy. If such conservative treatments do not provide relief to the patient, surgery is often the only effective treatment. 
     The most common cause of heel and arch pain is a condition called plantar fasciitis (heel pain). This is an inflammation of a thick, fibrous band of tissue, called the plantar fascia, that runs along the arch of the foot from the heel to the toes, and aids in stabilization of the arch during walking and running. Symptoms may involve one or both of the arch and the inside heel area. 
     Plantar fasciitis is caused by a mechanical imbalance in the foot called pronation. Over-pronation causes the foot to roll in towards the arch and big toe area. The plantar fascia inserts in the heel bone and then spreads out and joins the toes. When the foot rolls in (pronates) the plantar fascia must try and stretch, but it cannot. Therefore, the fascia pulls at its insertion at the heel bone. In extreme cases, this pulling Causes plantar fasciitis, a painful and often debilitating condition. 
     There have been numerous studies reporting various success rates for conservative care treatments for chronic heel pain. Even with the high success rate of conservative care, a percentage of heel pain patients eventually become surgical candidates. Historically, a wide range of “open” techniques have been used to perform plantar fasciotomies. More recently, endoscopic techniques, which can be performed through one or two small incisions, have been used to perform less invasive plantar fasciotomies. Studies of these endoscopic techniques have shown a substantial reduction in post-operative morbidity and amount of time needed to return to normal activities when compared to traditional “open” techniques. 
     One such endoscopic technique for the performance of plantar fasciotomies is shown and described by McNamara et al. in U.S. Pat. No. 5,620,446. The device shown in the &#39;446 patent includes a cutting instrument with a knife blade with a palpation end to sever tissue without snagging while palpating underlying tissue. The instrument comprises an elongated shaft having proximal and distal ends, a handle secured to the proximal end for use in manipulating the instrument, and the distal end having a generally blunt forward portion extending at an angle from the shaft and including an excising portion generally facing the proximal end of the shaft. In using the instrument, a sleeve is driven into the patient&#39;s foot from a medial aspect to a lateral aspect of the heel, i.e. entirely through the patient&#39;s foot. Visualization is made through the use of an arthroscopic camera, which is introduced through an open end of the sleeve on the medial aspect of the foot. The other open end of the sleeve is used as a working portal for the introduction of various surgical instruments to operate caudally on the line of insertion. 
     While this technique may have advantages over previous, more invasive techniques, it still requires incisions on both sides of the heel, and the sleeve must be large enough to accommodate both the camera and the cutting instrument, which in itself creates a trauma to the patient&#39;s foot and heel. Further, the instrument is expressly designed for the entire excision of the plantar fascia. It is known that excision part way, for example half way, through the plantar fascia is often sufficient for the complete relief of the patient&#39;s chronic heel pain. 
     Barrett et al., in U.S. Pat. No. 5,269,290, describe an endoscopic plantar fasciotomy procedure to relieve the symptoms of heel spur syndrome. A small, vertical incision is made in the medial side of the foot, and the adipose tissue is spread. A fascial elevator is inserted into the first incision to separate the plantar fascia from the surrounding tissue, creating a channel. A slotted canula and trocar are inserted into the channel, and a second incision is made on the lateral side of the foot, allowing the canula and trocar to substantially pierce the foot. The trocar is removed, and an endoscope is inserted into the canula through the medial portal. A cutting instrument is inserted into the lateral portal of the canula, and is used to release the plantar fascia from the heel bone. This procedure, like others in the art, suffer the drawbacks in that (1) incisions must be made on both sides of the foot; (2) the instruments must be made large enough to accommodate the endoscope; and (3) the instrument is designed to cut entirely through the plantar fascia, where cutting partially through the fascia would relieve the patient&#39;s pain. 
     Less invasive instruments have been proposed for other surgical techniques. For example, Strickland et al., in U.S. Pat. No. 6,179,852, describe a carpal tunnel device and method for carpal tunnel release surgery. However, the physiological structure in around the heel are quite different than those of the hand, and thus the capture clip is not well suited for the foot and heel. Further, as with the McNamara device, the Strickland instrument is used to completely divide the carpal ligament. 
     Thus, there remains a need for a technique and an instrument for performing plantar faciotomies that is less invasive than known techniques and instruments. The present invention is directed to such a technique and such an instrument. 
     Another source of chronic pain in the foot is Morton&#39;s neuroma. A neuroma is a benign tumor of a nerve. Morton&#39;s neuroma is not actually a tumor, but a thickening of the tissue that surrounds the digital nerve leading to the toes. It occurs as the nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot. Morton&#39;s neuroma most frequently develops between the third and fourth toes, usually in response to irritation, trauma, or excessive pressure. Treatment of this condition usually begins with shoewear adaptations. Sometimes simply moving to a wider shoe will reduce or eliminate the symptoms. An injection of xylocalne and cortisone into the area may help temporarily. If this fails to resolve the pain, surgery may be suggested. Surgery has traditionally involved removing the neuroma, and since the neuroma is part of the nerve, the nerve is removed as well. This results in permanent numbness in the area supplied by the nerve. Thus, there remains a need for a surgical instrument and a technique for treating Morton&#39;s neuroma which would eliminate the necessity of removing the neuroma, and therefor the nerve. The present invention is also directed to satisfying this need in the art. 
     SUMMARY OF THE INVENTION 
     This new minimally invasive approach allows the surgeon to safely and accurately incise the plantar fascia through a small single incision by achieving the accuracy and efficiency of endoscopy with the simplicity of an open approach. Therefore, the surgeon can utilize a set of minimally invasive instruments to isolate and incise a predetermined amount of the plantar fascia without any intrinsic tissue damage. The plantar fascia can be easily incised through a small vertical incision, e.g. ¾ cm. 
     The instrument of the invention comprises a self-adjusting clamp having a handle with a pair of substantially parallel prongs or tines extending from the handle, all formed as a unitary body or article of manufacture. The handle and prongs define a channel to receive a knife. The knife comprises a handle, a scalpel, and an extension coupling the scalpel to the handle. One advantage of the knife adapted for use in the clamp is that it defines a mirror image about a central axis. In this way, the surgeon need nor concern himself with whether the knife is oriented properly. Also, the extension arm of the knife includes graduations to assist the surgeon in predetermining precisely the distance of cut in using the instrument. 
     The upper prong of the clamp includes a downwardly extending capture pad having a bottom surface substantially parallel to the inner surface of the lower prong. This feature assists the surgeon in precisely locating the instrument on the plantar fascia, or on other ligaments of interest. Further, the upper and lower prongs define a mouth, having a continuously increasing distance between upper and lower prongs so that the clamp is guided onto the tissue target of choice in a non-invasive manner. 
     These and other features and advantages of this invention will be readily apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, more particular description of the invention, briefly summarized above, may be had by reference to embodiments thereof which are illustrated in the appended drawings. 
         FIG. 1  is a side section view of a self-adjusting clamp and a side view of a knife insertable into the clamp in the performance of the technique of this invention. 
         FIG. 2  is a top view of a clamp in partial section and a top view of a knife insertable into the clamp. 
         FIG. 3  is a perspective view of the clamp and knife as it is inserted into a patient&#39;s foot from a medial aspect. 
         FIG. 4  is a perspective view of the clamp and knife, illustrating partial incision of the plantar fascia. 
         FIG. 5  is a side section view of the clamp and knife with surrounding tissues during the performance of the technique of this invention. 
         FIG. 6  is a top view of the instrument of this invention severing a transverse metatarsal ligament. 
         FIG. 7  is a side view of the clamp and knife with surrounding tissues while severing a transverse metatarsal ligament. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     So that the principles of the present invention may be better understood, the presently preferred embodiments of the invention will now be described in detail. It is to be understood, however, that no limitation of the scope of the invention is thereby intended, such alterations, modifications, and further applications of the principles of the invention being contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIGS. 1 and 2  depict a surgical device  10  constructed in accordance with one embodiment of the present invention. The device  10  includes a ligament clamp or sheath  12  and a knife  14 . The ligament clamp  12  may be made out of spring steel, stainless steel, plastic, or any combination of the three, but is preferably made of stainless steel in upper and lower halves (not shown) and welded together to form a unitary body and then machined to make the clamp  12  as shown in  FIGS. 1 and 2 , a feature of the present invention. Portions of the knife  14  may be made from stainless steel. As shown and described below in respect of  FIGS. 3 ,  4 , and  5 , the knife  14  slides through a central guide channel  16  of the clamp  12 , to incise the selected ligament held within the clip  12 . 
     The clamp  12  comprises primarily a handle or body portion  18  and a prong portion  20 , formed as a unitary article of manufacture. The body portion  18  includes a proximal end  17  and a distal end  19 . The handle portion  18  includes an ergonomic grip  22  to assist the surgeon in manipulating the device. The prong portion  20  includes an upper prong  24  and a lower prong  26 . The lower prong  26  defines an angled surface  27 , which in use of the instrument helps to avoid the clamping of tissue other than the target ligament. The upper prong  24  defines a capture pad  28  having a tissue gripping surface, which is substantially parallel to an upper surface  30  of the lower prong. Thus, the capture pad extends from the upper prong toward the lower prong in order to grip tissue between the prongs. 
     Extending laterally from the surface  28  is an angled face  32 , thereby creating a mouth  34  having a continuously increasing clearance distance between the upper and lower prongs, another feature of the invention. Further, the surface  28  runs parallel to a bottom surface  36  of the upper prong, and is lower than the surface  36 . These features of the present invention enable the surgeon to palpate the tissues surrounding the plantar fascia and precisely position the device, thereby eliminating the need for any endoscopic equipment. These features also minimize the damage during surgery of tissues surrounding the surgical site. Note also that the upper prong has an upper surface  21  that is substantially parallel to a lower surface  23  of the lower prong. 
     Another feature of the present invention resides in the fact that the distance between the prongs, indeed the distance between the capture pad and the upper surface of the lower prong is self-adjusting. The mouth  34 , defined in part by the surface  32 , moves onto and on either side of the target ligament, and as the capture pad rides up onto the ligament, the prongs move apart to accommodate the ligament. The distance between the capture pad and the upper surface of the lower prong is typically about 2 mm, and as the clamp is moved onto the plantar fascia, for example, the distance can spread to 6-8 mm, for example. Further, because the surface  32  is preferably located on the upper prong, the upper prong tends to flex more than the upper prong. This feature of the invention adjusts the instrument to differing thickness of fascia or other ligaments, and pushes other, surrounding tissue out of the way. 
     The central guide channel  16  of the clamp defines a mouth  38  where the knife  14  is inserted into the clip  12 . The channel  16  then extends through the handle portion  18  and into the clip portion  20 , terminating in a stop  40 . 
     The knife  14  comprises primarily a handle  41 , a graduated extension arm  42 , and a scalpel  44 , preferably attached to the arm  42  as with rivets  46 , although other appropriate attachments may be used. The arm  42  includes a scale, preferably marked in centimeters, to assist the surgeon in precisely cutting the target ligament a predetermined distance. 
     In  FIG. 2 , note that the knife  14  is oriented longitudinally along a centerline  43 . Furthermore, each half of the knife  14 , on either side of the centerline  43 , is a mirror image of the other half. Thus, the knife may be reversed and still fit within the central guide channel  16 , another feature of the present invention. 
     Now that the structure of the surgical instrument of the present invention has been described in detail, the device will now be described in its intended environment of performing surgical procedures. 
     Procedure for Plantar Fasciotomy 
       FIGS. 3 through 5  depict the use of the instrument of this invention in performing a plantar fasciotomy. While the following description is directed to plantar fasciotomy, the same procedural steps may be used in incising the Achilles tendon. Prior to inserting the instrument of this invention, the surgeon first prepares the surgical site. The surgeon begins site preparation by palpating the medial tuberosity of the calcaneous plantarly. An incision  50  is then made about 1 cm distal from that point. A centerline  52  is then marked along the bottom of the patient&#39;s heel with a surgical marker. Preferably, using a #15 blade, the ¾ cm to 1 cm vertical incision  50  is made at the medial aspect of the heel just distal to the origin of the medial band of the plantar fascia  54 , with the incision starting approximately one centimeter from the plantar aspect of the heel and ending well below the neurovascular bundle. 
     Utilizing small curved Metzenbaum scissors (not shown), the incision is deepened to start a plane of approximately one centimeter under the plantar fascia  54  and dorsal to the subcutaneous tissue  56 , as shown in  FIG. 5 . A small, slightly curved tool (not shown) is then used to extend the plane across to the lateral aspect of the plantar fascia. Another tool, referred to as a fascia separator and constructed in a manner similar to the clamp, is then introduced to separate the plantar fascia  54  from both plantar and dorsal surrounding tissue. This tool has an upper and lower prong separated by a 5 mm gap. The lower prong extends approximately ½ inch farther than the upper prong to allow for initial palpation of the underside of the fascia before introduction and capture of the plantar fascia. 
     After removal of the separator, the clamp  12  of this invention is introduced and positioned securely around the plantar fascia using the same palpation technique used previously with the tissue locator and fascia separator. The position of the clamp around the plantar fascia is most clearly shown in  FIG. 5 . The design allows for isolation of the plantar fascia and protects the surrounding soft tissue structure  56  and  58  from damage during the procedure. The longer, lower prong  26  of the device is plantar to the fascia and the short upper prong  24  is dorsal. The slotted channel  16  extends throughout the handle and passes throughout the length of the device allowing the passage of the blade  14  while incising only the enclosed fascia. The calibrated extension arm or shaft  42  of the knife  14  is marked with 0.5 centimeter graduated increments  60  that are used as a reference point to the proximal end of the handle when the blade is placed on the bottom of the foot in the position needed to make the desired length of cut. 
     The knife  14  is then placed into the device, as shown in  FIG. 4 , and pushed toward the lateral aspect of the foot, with negative pressure and as the foot is dorsi-flexed until it reaches the previously determined calibrated mark. The surgeon can feel resistance and hear the distinct sound of the plantar fascia being incised. Note in  FIG. 4  that the incision has been made partway through the fascia to a predetermined extent. The clamp and the knife are then removed and the incision is closed with one or two interrupted sutures. Prior to closing the incision, the tissue locator, previously described, can be reintroduced to palpate for any remaining uncut fibers of the plantar fascia  54 . 
     Procedure for Intermetatarsal Nerve Decompression 
     The surgical instrument of this invention is also particularly adapted for the performance of intermetatarsal nerve decompression to relieve Morton&#39;s Neuroma. This procedure using the present invention is shown in  FIGS. 6 and 7 . Using a straight edge instrument (not shown), a pre-surgical mark  70  is made paralleling the metatarsal heads in order to define the correct path for introduction of the clamp and preparatory instruments. Using a #15 blade, a 7 mm vertical incision  72  is made in the web space. This incision is made vertically to protect the neurovascular bundle to the toe. A small curved Metzenbaum scissor (not shown) is then used to palpate and create a small plane on the plantar aspect of the transverse intermetatarsal ligament (TIML)  74 . The tissue locator, previously described, is then used to create a plane across the underside of the ligament  74 . Care is taken to ensure that all instruments are introduced in a paralleling manner to the adjacent metatarsals. The separator is then introduced in order to separate the TIML  74  from surrounding tissue  76  and  78  and to create planes plantar and dorsal to the TIML for proper placement of the device. As previously described, the separator has a upper and lower prong separated by a 5 mm gap. The lower prong extends approximately 0.5 inch further than the upper prong to allow for initial palpation of the underside of the ligament before introduction and capture of the TIML. 
     After removal of the separator, the clamp  12  is then introduced and positioned securely around the ligament  74  using the same palpation technique used previously with the tissue locator and separator. Note that the capture pad moves beyond the ligament  74  and that the entire ligament is to be incised in this procedure. Thus, no measuring of a predetermined distance of cut is required, as in the previously described plantar fascia procedure. The device design allows for isolation of the TIML and protects the nerve and surrounding soft tissue structures  76  and  78  from damage during the procedure. The longer, lower prong  26  of the device is plantar to the ligament and the short upper prong  24  is dorsal. The knife is then introduced into the channel  16  to incise only the enclosed TIML. 
     Once the device is properly positioned, the knife  14  is then introduced into the slotted channel to allow for a controlled cut which can be predetermined using the measurements of the blade extension arm or shaft. While the blade is passing throughout the slotted channel, the surgeon can feel resistance and hear the ligament being incised. The clamp and knife are then removed. The tissue locator can then be reintroduced to palpate between the metatarsal heads for confirmation of the successful release. Then, the incision is closed with one or two interrupted sutures. 
     The principles, preferred embodiment, and mode of operation of the present invention have been described in the foregoing specification. This invention is not to be construed as limited to the particular forms disclosed, since these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention.