The first metatarsal rise sign: a simple, sensitive sign of tibialis posterior tendon dysfunction.

Although foot deformation starts in the early stage of tibialis posterior (TP) tendon dysfunction, this condition is often overlooked or misdiagnosed. We observed consistently a clinical sign of TP tendon dysfunction that, to our knowledge, has not yet been described. Patients were tested while they were standing and fully weight-bearing with both feet. When the shank of the affected foot was taken with one hand and externally rotated, or when the heel of the affected foot was taken with one hand and brought passively into a varus position, the head of the first metatarsal raised in the case of TP dysfunction and remained on the ground in normal TP function. The purpose of this prospective study was to validate this clinical finding by surgical exploration, and to compare its sensitivity with other common clinical signs. Our series included 21 consecutive feet with TP tendon dysfunction (19 patients). The deformity was supple in 12 feet and fixed in 9 feet. Radiographs and magnetic resonance imaging were found to be unreliable in diagnosing dysfunction of the TP tendon. While other clinical signs (too many toes, the single-heel rise, and the double-heel rise) were noted to be negative in 20% to 35%, we found our first metatarsal rise sign to be positive in all cases of TP tendon dysfunction. This simple clinical test enables us to recognize and treat a dysfunction of the TP tendon at an early stage, when the foot is still supple. As the foot deformation progresses, early treatment may be the most effective measure in preventing long-term functional impairment.