Ulnar subluxation of the extensor digitorum communis tendon: a case report and review of the literature.

Ulnar subluxation of the extensor digitorum communis tendon at the MCP joint occurs infrequently in the nonrheumatoid patient and is secondary to one of four reported etiologies: traumatic, spontaneous, congenital, or epileptic. If symptomatic, patients may present with pain, swelling, a sensation of the tendon "snapping", "catching", "locking", or the inability to fully extend the MCP joint. Conservative and operative interventions have been recommended as treatment options. In the acute traumatic dislocation (less than ten days post injury), satisfactory results may be obtained with simple splinting with the MCP joint in extension. Patients who have failed conservative management or have a more chronic or degenerative dislocation may require surgical correction. The successful surgical repair must meet two requirements: (1) the tendon must be accurately aligned over the MCP joint to diminish the forces causing the dislocation to occur, and (2) the repair must be able to withstand the ulnar forces incurred during flexion of the joint. Realignment of the extensor tendon and direct repair of the radial sagittal band may be sufficient in acute traumatic, congenital, or spontaneous cases if the tissue is sufficient. In chronic dislocations or in cases with atrophic or degenerative tissue, reconstruction with augmentation of the radial restraints to the extensor hood is advised.