Metakarpofalangiale

Metakarpofalangiale, commonly referred to in English as the metacarpophalangeal joints (MCP), are the articulations between the metacarpal bones of the hand and the proximal phalanges of the fingers. There are five MCP joints in each hand, one for each digit, including the thumb.

Anatomy and structure: Each MCP joint is enclosed by a joint capsule strengthened by radial and ulnar collateral ligaments and reinforced on the palmar side by the volar (palmar) plate. The bases of the proximal phalanges articulate with the heads of the metacarpal bones. Joints for digits 2–5 are typically ellipsoid (condyloid) joints with two degrees of freedom, permitting flexion-extension and abduction-adduction. The first MCP joint (thumb) is functionally more hinge-like, mainly allowing flexion and extension with limited lateral movement. The extensor mechanism, intrinsic muscles (interossei and lumbricals), and the flexor tendons cross the joint and contribute to movement and stability.

Function and movement: The MCP joints enable finger flexion required for gripping and pinching, as well as extension to straighten the fingers. Abduction and adduction move the fingers toward or away from the midline of the hand, aiding precision grip and hand alignment. The ligaments and volar plate limit hyperextension and stabilize the joint during grasp.

Clinical relevance: MCP joints are commonly involved in rheumatic and degenerative diseases. Inflammatory conditions such as rheumatoid arthritis can cause synovitis, swelling, and ulnar drift, while osteoarthritis can lead to joint space narrowing and deformity. Trauma can cause sprains or dislocations. Diagnosis is aided by X-ray imaging; ultrasound or MRI may assess soft tissues. Treatments range from rest, splinting, and anti-inflammatory medications to injections or surgical options such as joint debridement, reconstruction, arthroplasty, or fusion in severe cases.