Locked Metacarpophalangeal Joint of the Middle Finger Caused by a Lipoma in the Flexor Tenosynovium: A Case Report.

Abstract

The locking of the metacarpophalangeal (MCP) joint of a finger is a common entity that is characterized by a loss of active and passive extension of the MCP joint with normal mobility of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints. This disorder should be distinguished from “trigger finger,” which occurs much more frequently. The locked MCP joint mostly occurs with sudden onset in the index or middle finger in adults or the elderly1. Locking often is caused by the collateral or accessory collateral ligament that catches on the prominent radial condyle of the metacarpal head or osteophytes on the volar metacarpal head1. Other reported causes are irregularities of the articular surfaces of the MCP joint, tears of the collateral ligaments or palmar plate, an intra-articular loose body, and sesamoid entrapment2. We report a case of a locked MCP joint that was caused by a lipoma in the flexor tenosynovium of the middle finger. The patient was informed that data concerning the case would be submitted for publication, and she provided consent. Over a two-year period, a sixty-two-year-old woman had experienced an extension lag at the MCP joint of the right middle finger without evidence of a particular cause. She denied any prior experiences of the snapping phenomenon in the involved digit. Although passive extension initially had been possible, the patient had developed painful triggering at the MCP joint and eventually had difficulty with writing and keyboard use. Subsequently, she had noticed a soft and painless tumor on the right palm. Upon initial presentation to our institution, there had been no change in …