A tear or rupture of the rectangular ligament that is formed by the plantar fascia andthe plantar capsule under the ball of the foot.
This ligament’s primary role is stabilizing the digit through resisting hyperextension of the digit. It is also important in reducing compressive loads of the metatarsal heads. It has a secondary function in guiding the line of pull for the some of the little muscles inside the foot.
Typically occurs at the 2nd metatarsophalangeal joint (MTPJ) but can occur on other MTPJ’s. It is characterized by localized pain underneath the MTPJ on forefoot. Often described as a “bruise” or “stone in the shoe”. It’s usually painful at the base of the proximal phalanx and is aggravated by dorsiflexion. Swelling is possible above and below the joint.
The condition progresses from an early stage increasing subluxation of the digit (partial dislocation). At this point the condition is reversible but if left unattended is likely to progress to chronic dislocation of the digit and what is termed “crossover toe” (see below image).