Role of plantar plate and surgical reconstruction techniques on static stability of lesser metatarsophalangeal joints: a biomechanical study.

BACKGROUND Disruption of the plantar plate of the lesser metatarsophalangeal (MTP) joints leads to significant instability. Despite the fact that plantar plate disorders are common, the best mode of treatment remains controversial with operative treatments having variable and somewhat unpredictable clinical outcomes. METHODS Lesser MTP joints from the second, third, and fourth toes from fresh-frozen cadaver feet were biomechanically tested: (1) intact, (2) with the plantar plate disrupted, and (3) following a Weil osteotomy, a flexor-to-extensor tendon transfer, or a Weil osteotomy with a subsequent flexor-to-extensor tendon transfer with testing in superior subluxation, dorsiflexion, and plantarflexion. RESULTS The plantar plate significantly contributed to stabilizing the sagittal plane of the lesser MTP joints. The flexor-to-extensor tendon transfer significantly stabilized the disrupted lesser MTP joints in both superior subluxation and in dorsiflexion. The flexor-to-extensor tendon transfer following a Weil osteotomy also significantly stabilized the disrupted lesser MTP joints in both superior subluxation and in dorsiflexion. CONCLUSIONS In this cadaver-based experiment, disruption of the plantar plate of the lesser MTP joints led to significant instability. After plantar plate disruption, the Weil osteotomy left the joint unstable. The flexor-to-extensor tendon transfer by itself increased the stability of the joint in dorsiflexion, but combined with a Weil osteotomy restored near intact stability against superior subluxation and dorsiflexion forces. CLINICAL RELEVANCE Surgeons using the Weil osteotomy for plantar plate deficient MTP joints may consider adding a flexor tendon transfer to the procedure. Techniques to repair the torn plantar plate directly are needed.