Pertinent Insights On Treating Second MPJ Pathology

Christopher L. Reeves, DPM, FACFAS, Amber M. Shane, DPM, FACFAS, Larissa McDonough, DPM, AACFAS, and Francesca Zappasodi, DPM, AACFAS

   In patients with digital contractures or crossover toe deformities, often the initial culprit is a hallux abductovalgus deformity. This deformity, while not always symptomatic in the patient, may necessitate surgery if it is a direct contributing factor to the dorsal medial migration of the second toe. In addition, one must evaluate the second ray to specify the correction of the hammertoe deformity that is present. If a callus or plantar pain is present upon palpation of the second metatarsal head, surgeons may utilize a decompression or dorsiflexory metatarsal osteotomy.

   When second MPJ plantar callosities are present, evaluate instability in the first tarsometatarsal joint. If instability is apparent on clinical exam, a procedure such as a first tarsometatarsal joint arthrodesis may correct and stabilize the mechanics of the forefoot, and reduce the excessive pressure at the second metatarsophalangeal joint complex.

   A large number of contracted digits result from a long second metatarsal. These elongated metatarsals experience chronic overload and ultimately result in weakened plantar capsular structures that allow for joint instability, which can progress to dislocation. In this situation, we recommend a metatarsal decompression osteotomy to restore an anatomic parabola and the appropriate allocation of plantar pressures.

   The retrograde subluxation of the proximal phalanx of a rigidly contracted toe on the corresponding metatarsal head only further exacerbates the overloading of the joint. By already addressing the metatarsal position, one can correct the hammertoe deformity of the second toe with either proximal interphalangeal joint arthroplasty or arthrodesis. A variety of implants are available to keep an arthrodesis site internally aligned and compressed until fusion occurs. Also, one can release contractures in the soft tissue structures with the use of a skin plasty, such as a V-Y incision. If there is a residual transverse plane deformity of the second toe after decompression osteotomies and hammertoe repair, consider a lateral second MPJ capsulorrhaphy and or a medial capsulotomy.

   If there is instability through the Lachman vertical stress test when evaluating the second toe, surgical strategies may have to incorporate a plantar plate repair or a flexor tendon transfer. In patients with plantar plate rupture, historical approaches for repair of the plantar plate apparatus include both dorsal and plantar incisions. A more popular surgery includes a dorsal approach with concomitant metatarsal osteotomy to create temporary intraoperative exposure to the plantar plate and postoperative shortening of the metatarsal length. Reefing the plantar tissues with a suture while holding the toe in a slight plantarflexory position allows for a better repair.

   A flexor tendon transfer such as the Girdlestone procedure is typically indicated with flexible digital deformities. This tendon transfer enables the tendon to plantarflex the MPJ and extends the distal digital joints. The procedure can also aid in stabilization when sagittal plane instability is present at the second MPJ or a complete plantar plate tear is beyond repair. One can perform this procedure with a one or two incision technique. The surgeon can harvest the tendon and pass it through the proximal phalanx with the security of a suture anchor, or split the tendon longitudinally and tie it dorsally on the proximal phalanx.

   For patients who demonstrate progressive radiographic destruction of the articular surface of the second metatarsal head, one should suspect an acute Freiberg’s infraction. Initial radiographs early on may only demonstrate an area of linear subchondral lucency in the second metatarsal head. This radiographic feature signifies osseous resorption and is referred to as the crescent sign. Longer periods of non-weightbearing and offloading are initially required until symptoms acquiesce.

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