2nd MTP Joint Arthritis
Primary or non-traumatic degenerative osteoarthritis of the 2nd MTP joint is rare. A few studies have examined its pathogenesis in the context of the instability of the joint, Freiberg’s infraction, or trauma. Hallux valgus is also speculated to increase the load on the second MTP joint, inducing degenerative osteoarthritis, and the severity of arthritis may be correlated with the severity of the hallux valgus.
The second metatarsal is the longest of all metatarsals and has been shown to sustain the greatest stresses during normal activity. The keystone configuration of the tarsometatarsal joint confers substantial stability to the second metatarsal base making this bone the least mobile.
This potentially increases the stress on the metatarsal head distally. The toe dorsiflexion pushes the metatarsal head downwards toward the sole during the push-off phase, generating compressive and shear forces at the dorsal aspect of the head, and damaging the articular cartilage as the base of the proximal phalanx rides dorsally over the metatarsal. These facts may explain the association between second toe rigidus and a functionally long second metatarsal.
Patients report a generalised decrease in range of motion, with particular limitation in dorsiflexion, associated with localised pain and tenderness. This clinical manifestation differs from that of second metatarsophalangeal joint instability.
In contrast to the radiographic findings in Freiberg’s infraction, the findings in primary arthritis of the 2nd MTPJ are similar to those in degenerative arthritis of the other joints, especially hallux rigidus. These include narrowing of the joint space, osteophytic changes, primarily involving the dorsal aspect of the joint and spurs along the MT head and proximal phalanx base.
In cases in which the second metatarsal is long or plantarflexed, and associated with chronic, well-localized forefoot pain, then decompression of the MPJ should be the primary procedure. Repairing the primary stabilizing structure of the MPJ (the plantar plate) becomes a mandatory adjunct.
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Jaeho Cho & Jung-Rae Kim & Woo-Chun Lee, Degenerative osteoarthritis of the second metatarsophalangeal joint: second toe rigidus, International Orthopaedics (SICOT) (2013) 37:1863–1869.