An Alternative Approach To Plantar Plate Derangement

Author(s): 
By Kerry Zang, DPM

     Plantar plate derangement with synovitis of the metatarsophalangeal joint complex is a progressively degenerative condition with an inflammatory component.1 Recent clinical experience suggests that one can treat these pathologies successfully using plasma-mediated, radiofrequency-based microdebridement.      While the plantar plate of the metatarsophalangeal joint shows signs of degeneration, the metatarsophalangeal joint complex itself is inflamed (i.e. synovitis). Clinicians often find this condition in conjunction with the triad of hallux abductovalgus deformity, metatarsalgia secondary to prominence of the metatarsal head and digital deformity.      During the physical examination, the physician will notice the following findings:      • medial deviation of the appropriate digits;      • contracture with pain on palpation of the dorsal medial aspect of the second metatarsophalangeal joint complex;      • increased pain on palpation in the metatarsophalangeal joint complex upon distraction of the involved digit;      • pain on palpation at the lateral plantar aspect of the capsule of the second and/or other metatarsophalangeal joint complexes;      • clinically prominent and painful metatarsal heads;      • pain with rotational forces at the base of the proximal phalanx on the head of the corresponding metatarsal;      • positive vertical instability with stress testing of the involved metatarsophalangeal joint. With plantar plate derangement, the instability is up to approximately 3 mm. Over 3 mm indicates rupture of the plantar plate.      One may also note frictional keratosis inferior to the metatarsal head.      It is important to note that the most commonly involved joint for plantar plate derangement in the foot is the second metatarsophalangeal joint but sometimes one may see involvement of other lesser metatarsophalangeal joints. This is usually a direct result of either long metatarsals or other structural imbalances that lead to increased pressure at the level of the metatarsophalangeal joints, and repetitive stress from the biomechanical imbalances that are present.      Diagnostic ultrasound is also a valuable tool in diagnosing plantar plate derangement. It clearly enables visualization of the plantar plate to determine whether there is early derangement, degenerative changes or rupture. Doppler enhancement will also help the physician ascertain if the process is of an inflammatory nature or degenerative capsulopathy. With the ultrasound, we can also determine the presence and extent of the inflammatory synovitis on the dorsal aspect of the involved metatarsophalangeal joint.      The normal ultrasound appearance of the plantar plate is one of ligament and tissue continuity at the metatarsophalangeal joint without significant fluid in the joint space. When it comes to a tear in the plantar plate, the clinician will see a disruption in the continuity (hypoechogenicity) of the tissues at the metatarsophalangeal joint. Varying degrees of derangement are categorized as small, moderate or large tears of the plantar plate depending on the amount of disruption. Clinicians will also see increased edema or synovitis within the joint, which one can confirm via the use of power Doppler. If you diagnose the plantar plate derangement early on in the disease process, conservative treatment efforts might be beneficial.

Pertinent Pointers On Conservative Care

     Conservative care would consist of a combination of functional orthotic control and antiinflammatory medications. The clinician should be careful to avoid steroid injections into the area as this would increase the risk of rupture of the already weakened degenerative plantar capsulopathy. One can utilize compounded, nonsteroidal, non-systemic antiinflammatory medication. I use a compound made from ketoprofen (10%), ibuprofen (10%), piroxicam (2%) and cyclobenaprine (2%), three different antiinflammatory medications with a muscle relaxant. The benefit of this compound is its lack of cross-reactivity with other systemic medications the patient may be taking as it is utilized locally. In rare occasions, the patient may develop a rash and should discontinue its use immediately.      One may also strap the involved digits together and hold them in plantarflexed position for a few weeks to help in offloading the plantar plate. These efforts generally take approximately three to six weeks to demonstrate any degree of success. If conservative efforts are unsuccessful, consider surgical intervention. In place of the traditional surgery, one might offer patients the option of the microdebridement procedure.

Comparing Microdebridement To Conventional Surgical Treatment

     Conventional surgical treatment of plantar plate derangement with synovitis most commonly consists of dissecting the plantar plate/capsule and realigning soft tissue dorsally. One would usually perform this procedure in conjunction with repair of the digital deformity. More recently, alternative surgical repair consists of decompressing the metatarsophalangeal joint complex with a shortening osteotomy of the metatarsal. Although both types of surgery are generally successful clinically, postoperative recovery can take several months.      Plantar plate derangement is a capsulopathy but the condition appears to demonstrate a similar pattern of painful hypovascular tissue degeneration as the overuse injuries of tendinosis and fasciosis. During the past few years, surgeons have successfully used plasma-mediated, radiofrequency-based (Coblation®, ArthroCare) microdebridement to treat symptomatic chronic tendinosis.2 The objective of this microdebridement approach is to promote a low-grade inflammatory response in treated tissue. This stimulates neovascularization, which initiates a biochemical profile associated with the healing process in degenerated tissue and the formation of new blood vessels.3-7 Some are currently using plasma-mediated, radiofrequency-based microdebridement to treat refractory symptoms associated with tendinosis in the shoulder and elbow.2,8      In my clinical experience utilizing this technique over the past three years, I have found it is excellent in treating Achilles tendinosis and intractable plantar fasciosis. Since plantar plate derangement shows evidence of having similar characteristics to the pathologies of tendinosis and fasciosis, this radiofrequency-based procedure could provide an excellent alternative to surgical dissection of the capsule for treating this capsulopathy. The microdebridement procedure may offer substantial benefits over conventional surgery, including quicker recovery and less risk of postoperative complications.

Step-By-Step Pearls For The Procedure

     Accordingly, we recently undertook a study to evaluate the technical ease of using this approach to treat patients with plantar plate derangement, metatarsalgia and synovitis of the second metatarsophalangeal joint complex, and to assess early postoperative clinical findings.      In regard to the surgical repair, we initially address the metatarsalgia, proceed to repair the plantar plate derangement and finally, using the radiofrequency-based device to ablate the synovitis affected tissue of the second metatarsophalangeal joint complex, we perform the microcapsulotomies of the plantar plate.      To treat the plantar plate derangement, one makes an s-shaped incision from the distal third of the second metatarsal shaft and carries the incision to the base of the proximal phalanx. Then you would expose the superior aspect of the head and neck of the metatarsal via sharp dissection. Proceed to open and expose the dorsal aspect of the metatarsophalangeal joint.      Then we perform a shortening Weil-type osteotomy of the second metatarsal.9,10 We perform the osteotomy from the dorsal distal aspect of the metatarsal and translate it toward the proximal plantar, just proximal to the plantar condyles and parallel to the plantar aspect of the foot. We adjusted the distal osteotomized capital fragment proximally (3 to 5 mm) to eliminate clinical prominence of the metatarsal head in the plantar position. We proceeded to fixate the osteotomy site with two 0.035 mm guide wires and secured it with either a 2.0 mm or a 2.4 mm compression screw.      After decompression of the second metatarsophalangeal joint and internal fixation of the second metatarsal shaft, we applied gentle digital traction to distract and open up the second metatarsophalangeal joint complex. Using a 2.7 mm angled arthroscope, one can evaluate the joint to determine the extent of the synovitis. Following inspection, the surgeon can perform a synovectomy using the Topaz microdebrider device (ArthroCare) as directed by the manufacturer’s instructions.      With continued digital traction, we examined the plantar capsular structures and plantar plate. We used the Topaz device to perform the microcapsulotomy procedure in the degenerated plantar plate. The purpose of this step is creating a low-grade inflammatory response necessary for stimulating a healing response in the degenerated tissue. For both ablation procedures, one can use the Topaz device at controller setting 4.      For the microcapsulotomy, however, we used the system timer (set at 0.5 seconds) while making each microablation in order to specify a sufficient ablation. We created microablations over the affected tissue region to form a grid-like pattern. Every fourth microablation was slightly deeper in order to ensure adequate penetration of treatment. The affected plantar plate area usually required nine to 12 microablations.      After concluding the microablation portion of the procedure, we irrigated the treated area and closed it in standard fashion. We subsequently repaired any associated contributory deformities, such as hallux adductovalgus and/or hammertoe deformity as appropriate.      In regard to the radiofrequency-based portion of the procedure, it was slightly more challenging than surgical resection. However, it did offer the benefit of preserving the plantar plate and avoided a plantar incision.

Assessing The Post-Op Results

     To date, we have treated 30 patients with the plasma-mediated radiofrequency-based microcapsulotomy procedure in lieu of surgical dissection of the affected plantar plate. We observed no postoperative complications or significant clinical events. Patients tolerated the procedure well and all recovered within a faster time frame than expected with surgical dissection.      Immediately postoperatively, patients were generally weightbearing with a walker boot. They received instructions to rotate the foot externally when ambulating in order to reduce pressure on the forefoot. When the patient was not in a weightbearing position, we encouraged the patient to remove the walker boot and exercise by flexing and extending the ankle joint and metatarsophalangeal joints.      Patients were normally able to return to sport shoes or supportive sport-type sandals between four and six weeks. During the recovery period, we performed a biomechanical evaluation and administered orthotic control as appropriate. Preliminary results have been excellent and follow-up is continuing.

In Conclusion

     The capsulotomy procedure using plasma-mediated, radiofrequency-based microablation was relatively easy to do and allows preservation of the plantar plate. Patients reported substantial reduction of pain postoperatively, providing promising preliminary results with this technique.      Plantar plate derangement occurs in conjunction with many conditions. The most common conditions are development of a progressive hammertoe deformity with medial deviation of the proximal phalanx, which is often associated with an isolated metatarsalgia of the involved metatarsal head. Isolated hyperextension injuries to the metatarsophalangeal joint can also cause derangement/rupture of the plantar plate. Peri- and post-menopausal women with a history of repetitive stress, such as daily use of high-heeled shoes, also appear to be prone to degenerative changes of the plantar plate.      Since plantar plate derangement is relatively prevalent, one should consider addressing it with techniques that are less invasive than plantar surgical dissection. Use of this technique may provide benefits over major plantar surgical dissection. Indeed, further controlled study of this approach would be valuable.      This less invasive procedure was particularly attractive since plantar plate derangement occurs in conjunction with several commonly presenting conditions. Once plantar plate derangement has persisted without responding to conservative care, this approach might provide an excellent alternative to surgical dissection since it may be associated with faster recovery and less risk of postoperative complications than surgical dissection. Dr. Zang is a Diplomate of the American Board of Podiatric Surgery, and a Fellow of the American College of Foot and Ankle Surgeons. He practices in Mesa, Ariz. Editor’s Note: For related articles, see “Point-Counterpoint: Is Plantar Plate Repair More Effective Than Flexor Tendon Transfer?” in the June 2006 issue of Podiatry Today, “Metatarsalgia: Is The Plantar Plate Important?” in the January 2004 issue or visit the archives at www.podiatrytoday.com.
 

 

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