A group of fifty patients, twenty-five of whom presented a limitation of extension of the fingers, and twenty-five a limitation of flexion of fingers, as a result of mechanical limitation at the interphalangeal joints, has been studied. In these patients, there were seventy-two interphalangeal joints subjected to surgery, in order to improve function after conservative measures had failed. An operative procedure in which a lateral approach is used allows the operator to excise a portion of the collateral ligament from each side of the joint without disturbing the stability in the proximal interphalangeal joint. At the same time it provides easy access to all other structures which may play a role in blocking extension or flexion of the fingers at the interphalangeal joints. The results in this series of patients lead to the conclusion that, when the interphalangeal joint is intrinsically in good condition as shown by the roentgenogram, one can expect a measurable improvement by the procedure of capsulectomy of the interphalangeal joints.