Joints are formed by two adjacent bones and these joints are covered by a capsule where. The capsule prevents the joint fluid from leaking out and maintains the optimum mechanical environment for the joint to function. This capsule can often get inflamed, resulting in chronic pain of the affected joint.
Most common joint affecting the foot is the 2nd metatarsophalangeal joint. The 2nd metatarsal is the longest of the five long bones of the foot and oftentimes is accompanied by a short 1st metatarsal. This can cause many issues including transfer metatarsalgia which eventually causes inflammation of the 2nd MPJ capsule.
Abnormal biomechanics of the foot coupled with repetitive microtrauma to the capsule causes connective tissue degeneration. This inflammation causes considerable discomfort and, if left untreated, can eventually lead to a weakening of surrounding ligaments that can cause dislocation of the toe.
Risk factors include tight calf muscles, long 2nd metatarsal, short 1st metatarsal, unstable arch due to flat foot deformity, bunion deformity, ill-fitting shoes. Diagnosis is clinical but X-rays are useful in ruling out other pathologies.
Treatment if caught early is conservative which include rest, ice, NSAIDs, stretching exercises and supportive shoe gear wear. Certain patients will benefit from a steroid injection in the joint capsule. Chronic capsulitis is usually accompanied with a dislocated 2nd digit. Surgical repair is often required for such cases in which the plantar plate is surgically repaired to bring the toe back down to its anatomical position.