This condition is a stretching or tearing of the volar plate, which can allow the finger to hyperextend and can interfere with normal hand function. The volar plate is a strong ligamentous structure on the underside of the finger at the point where the proximal and middle phalanx bones meet, called the proximal interphalangeal joint (or PIP joint). The volar plate keeps the finger from bending backwards at the PIP joint, and, together with the collateral ligaments, stabilizes the PIP joint from displacement.
Volar plate injuries can be caused by disease or trauma. Diseases such as rheumatoid arthritis can weaken and loosen the volar plate, leaving it susceptible to injury. Trauma to the finger, such as breaking a fall with an outstretched hand or catching a ball during athletic activity, can hyperextend or dislocate a finger and tear or rupture its volar plate and one or both of the collateral ligaments. In some cases, the bone at the attachment of the volar plate may fracture and be pulled away.
Symptoms of a volar plate injury include pain and swelling at the joint, tenderness on the palmar side of the joint, and joint instability. If the finger is dislocated, it may be noticeably out of alignment.
Most volar plate injuries can be treated with a flexed finger splint, followed by finger motion exercises and hand therapy. If the joint is unstable or a significant fracture has occurred, surgery will be required.