Point-Counterpoint: Is Plantar Plate Repair More Effective Than Flexor Tendon Transfer?
Yes. After discussing the importance of the plantar plate in facilitating MTPJ stability, this author points out key shortcomings of the flexor tendon transfer and emphasizes the more direct focus of plantar plate repair. By Leon Reber, DPM When it comes to pain below the metatarsal head, clinicians have described this with various names such as predislocation syndrome, monoarticular nontraumatic synovitis, capsulitis or simply metatarsalgia. Although the terminology varies, the one thing they have in common is pressure. Excessive pressure below the metatarsal head is the reason the patient has pain. Given the etiology, lesser metatarsal overload is actually a more descriptive and appropriate term. The second metatarsophalangeal joint (MTPJ) is most commonly involved. In the earlier stages of lesser metatarsal overload, the condition is sometimes misdiagnosed as a second innerspace neuroma. Pain associated with attenuation or rupture of the plantar plate represents the symptoms of a dysfunctional foot. Accordingly, one should focus on eliminating the biomechanical source of lesser metatarsal overload. Causes of lesser metatarsal overload include an insufficient first ray with or without hallux valgus, long second metatarsal and equinus.1-4 As with many disease processes, the etiology may be multifactorial and one should generally regard primary repair of the plantar plate as an adjunctive procedure. Recognition of each of the potential contributing factors that cause overload will allow the surgeon to effectively address not just the symptoms but the etiology as well. Instability of the MTPJ results from weakening of the periarticular structures, namely the plantar plate. Once the joint is unstable, the flexor tendons deviate the toe medially.5 Primary repair of the plantar plate has been gaining popularity because it addresses the actual focus of pathology. The plantar plate as a static stabilizer of the MTPJ is well known.6,7 However, the role of the plantar plate, when it comes to dynamic stability of the MTPJ, is underappreciated. The strongest attachment of the plantar plate is into the base of the proximal phalanx, which helps create a socket for the metatarsal head. The plantar plate is the only significant distal attachment of the plantar fascia. In fact, one can think of the plantar plate as a thickening of the plantar fascia below the metatarsal head. Given this relationship, the plantar plate is an integral part of the windlass mechanism that helps dynamically stabilize the MTPJ. How The Plantar Plate Stabilizes The MTPJ The windlass mechanism describes the effects dorsiflexion of the toes have on the foot. Dorsiflexion of the toes tightens the plantar fascia, which causes the arch to rise. In contrast, the reverse windlass describes the effects the foot has on the toes. Loading the foot through weightbearing tightens the plantar fascia and causes the toes to plantarflex. Hicks and Sarrafian recognized the plantar fascia as a plantarflexor of the toes through the reverse windlass mechanism. Sarrafian notes that upon weightbearing, “the toes are plantarflexed by the tensioning of the plantar aponeurosis.”8,9 As early as 1977, Scheck recognized the role of the plantar plate and plantar fascia as dynamic contributors to the MTPJs.10 Scheck further believed that elongation of the plantar structures creates a dynamic imbalance, resulting in hammertoe deformities. Hammel, et. al., consider the toes to have passive and active plantarflexors.11 They describe the plantar fascia as a passive plantarflexor and the flexor tendons as an active plantarflexor of the toes. They not only found the plantar fascia to be a significant flexor of the toes but found that the plantar fascia allows the flexor tendons to act more effectively. They demonstrated that when the flexor tendons pull without the stabilization of the plantar fascia, the toes had a tendency to curl. This study implies that without a stabilized MTPJ, the flexor tendons are a deforming force. The role of the plantar fascia as a plantarflexor and stabilizer of the toes is highlighted in case presentations in which plantar fascia ruptures and surgical excision have led to the development of hammertoes.12 The plantar plate essentially serves as a link that connects the plantar fascia to the proximal phalanx.