Locking of the metacarpo-phalangeal joint from a loose body. Report of a case.

Triggering of finger joints due to tendon lesions is a well known entity, but locking of the metacarpo-phalangeal joint due to a derangement of the joint or its capsule is uncommon. In 1949 Langenskiold reported two cases in which the collateral ligaments were catching on the metacarpal head and causing the locking; he noted that this possibility had been mentioned by Poirier in 1889. The same mechanism was responsible in the five cases described by Aston (1960). Goodfellow and Weaver (1961) reported five patients in whom locking was due to osteophytes on the volar aspect of the metacarpal head catching in the anterior part of the capsule and the volar plate; they pointed out that this type of lesion could explain the curious case reported by Alldred (1954). Locking from irregularities in the articular surface of the