Interphalangeale

Interphalangeale refers to the joints between the phalanges of the fingers or toes, commonly called the interphalangeal joints. In most fingers, there are two such joints: the proximal interphalangeal joint (PIP), located between the proximal and middle phalanges, and the distal interphalangeal joint (DIP), located between the middle and distal phalanges. The big toe typically has a single interphalangeal joint between the proximal and distal phalanx.

Anatomy and function

Interphalangeal joints are hinge-type synovial joints that permit mainly flexion and extension of the distal digits. They are reinforced by collateral ligaments on the sides and by a volar (palmar) plate on the underside, which helps prevent hyperextension and provides stability. The joint surfaces are covered with hyaline cartilage and enclosed by a fibrous joint capsule. The tendons of the finger flexors and extensors cross the joints to produce movement, and the nerves and blood vessels travel with the digits to supply sensation and perfusion.

Clinical relevance

Interphalangeal joints are commonly involved in injuries and degenerative conditions. Dislocations and fractures of the proximal, middle, or distal phalanx can affect these joints. Mallet finger refers to injury of the extensor mechanism at the DIP, while jersey finger denotes rupture of the flexor digitorum profundus tendon at the DIP. Osteoarthritis and inflammatory arthritides can involve the IP joints, with symptoms such as pain, swelling, and reduced motion. Treatment ranges from immobilization and physical therapy to surgical intervention in unstable injuries or severe joint degeneration.

Etymology

The term interphalangeal derives from Latin, meaning “between the phalanges,” and is used in various languages, with interphalangeale as a regional or historical form.