The boutonniere deformity.
Understanding the pathophysiology of the boutonniere deformity requires a complete understanding of the anatomy of the dorsal tendon apparatus. This unique tendon mechanism often becomes unbalanced, requiring correction of its components. Splinting is the cornerstone of treatment for the boutonniere deformity. In the acute stage, splinting ensures that the continuity of the central tendon to its insertion into the middle phalanx is maintained, and in the chronic stage, its function is to correct the flexion contracture of the PIP joint and stretch the retinacular ligaments. Splinting is also important postoperatively because it permits healing of the central tendon and lateral bands in their correct anatomic positions. Without proper splinting, the patient with the boutonniere deformity could not be successfully treated. Frequently, surgery is necessary, and the choice of procedure depends on the stage of the condition and the extent of the defect in the extensor tendon mechanism. The procedure also depends on the success of the splinting program and stretching of the tight retinacular structures. If passive joint mobility can be restored and if tendon imbalance and retinacular tightness persist, rebalancing is necessary. This rebalancing can be accomplished by a tenotomy of the terminal extensor tendon, a lysis or release of the retinacular structures, or release of the insertion of the extensor tendon at the base of the proximal phalanx. Reconstituting the defect in the central tendon over the PIP joint is accomplished by using a variety of procedures, including mobilization and advancement of the more proximal portion of the central tendon, shifting the lateral bands, or a tendon graft.