musculoskeletal and connective tissue disorders
Metatarsophalangeal Joint Pain
Introduction
Metatarsophalangeal joint pain usually results from tissue changes due to aberrant foot biomechanics. Symptoms and signs include pain with walking and tenderness. Diagnosis is clinical; however, infection or systemic rheumatic diseases (eg, rheumatoid arthritis, psoriatic arthritis) may need to be excluded by testing. Treatment includes orthotics, sometimes local injection, and occasionally surgery. (See also Overview of Foot and Ankle Disorders .) Metatarsophalangeal joint pain is a common cause of Metatarsalgia . Metatarsophalangeal joint pain most commonly results from misalignment of the joint surfaces with altered foot biomechanics, causing joint subluxations, flexor plate tears, capsular impingement, and joint cartilage destruction (osteoarthrosis). Misaligned joints may cause synovial impingement, with minimal if any warmth and swelling (osteoarthritic synovitis). The second metatarsophalangeal joint is commonly affected. It develops laxity to the collateral ligaments due to rigid Hammer Toe Deformity which allows the toe to sublux and dislocate out of the joint. As the disjointed toe attempts to strike the ground during ambulation, it causes a retrograde buckling force on the metatarsal head, which results in pain and abnormal pressure at the plantar aspect of the forefoot. Usually, inadequate first ray (first cuneiform and first metatarsal) function results from excessive pronation (the foot rolling inward and the hindfoot turning outward or everted), often leading to capsulitis, plantar plate injury, and hammer toe deformities. Overactivity of the anterior shin muscles in patients with pes cavus (high arch) and ankle equinus (shortened Achilles tendon that restricts ankle dorsiflexion) deformities tends to cause dorsal joint subluxations with retracted (clawed) digits and retrograde, increased submetatarsal head pressure and pain. Metatarsophalangeal joint subluxations also occur as a result of chronic inflammatory arthropathy, particularly Rheumatoid Arthritis (RA) . Metatarsophalangeal joint pain with weight bearing and a sense of stiffness in the morning can be significant early signs of early rheumatoid arthritis. Inflammatory synovitis and interosseous muscle atrophy in rheumatoid arthritis lead to subluxations of the lesser metatarsophalangeal joints as well, resulting in hammer toe deformities. Consequently, the metatarsal fat pad, which usually cushions the stress between the metatarsals and interdigital nerves during walking, moves distally under the toes; The first metatarsophalangeal joint is the most common location of Osteoarthritis (OA) in the foot. The joint cartilage is damaged due to trauma, deformity (eg, bunion) or systemic arthritides (eg. gout, rheumatoid arthritis) and results in a decreased dorsiflexion of the hallux. As the disorder progresses, the loss of dorsiflexion prevents the foot from functioning properly in the push-off phase of gait. The sesamoids located within the flexor hallucis brevis tendon fibrose and lose their inherent mechanical advantage for propulsion of the great toe off the ground. This causes an unintended use of the second metatarsophalangeal joint to compensate for the lack of first metatarsophalangeal joint range of motion, which causes pain and laxity at the second metatarsophalangeal joint. Metatarsophalangeal joint pain may also result from functionalhallux limitus, which limits passive and active joint motion at the first metatarsophalangeal joint. Patients usually have foot pronation disorders that result in elevation of the first ray with lowering of the medial longitudinal arch during weight bearing. As a result of the first ray elevation, the proximal phalanx of the great toe cannot freely extend on the first metatarsal head; the result is jamming at the dorsal joint leading to osteoarthritic changes and loss of joint motion. Over time, pain may develop. As joint space narrows due to arthritis, hallux rigidus can occur. Acute arthritis can occur secondary to systemic arthritides such as Gout , 