[The Omega "Omega" pulley plasty. A new technique to increase the diameter of the annular flexor digital pulleys].

The authors report a new technique of pulley plasty of the flexor digital system. It is not an operative procedure to reconstruct a damaged pulley but an original way to expand the volume of an intact pulley in order to adapt its volume to the diameter of the repaired flexor tendon. The flexor tendons ruptures in Verdan zone II and particularly in Tang zones IIA and IIB are often accompanied by an osteofibrous tunnel injury. Initially, the tendon sheath closure was advised after tendons repair. This sheath recovery had to have an effect on tendons nutrition by establishing the synovial cavity continuity and particularly to protect the tendons from adhesions formation. The closure of the digital tube was rapidly shown to be unnecessary creating an obstacle to the tendons movements without any effect on tendons healing. In primary tendon management, the tendon repair is associated with an increase of the tendon diameter. An incongruence appears with the surrounding digital tube with gliding resistance complicating the tendon injury recovery. In secondary tendon injury management, the flexor digital tube is subject to healing and inflammatory process. This situation with the absence of the flexor tendon generates a retraction with a collapse of the digital tunnel over the injured area. This incongruence between the repaired flexor tendons and the narrowed digital tube required a release of the retracted zone to restore an adequate volume. The only way reported is the "Venting" of a part or the total length of the pulley. This procedure even if it resolves the tendon gliding resistance, is still unacceptable. Indeed it destroys an important anatomical structure of the flexor tendon dynamic system. The flexor pulley Omega plasty "Omega" consists in releasing the lateral palmar attachment of the pulley enhancing its internal volume and increasing the flexor tendon gliding area. The digital tube is composed by the succession of five annular and three cruciform pulleys. The cruciform pulleys are thin and flexible. They retract during the digital flexion assuring the continuity of the digital tube, while the annular pulleys are thicker and fill a biomechanical function. There are two types of annular pulleys: the joint pulleys as A1, A3 and A5; they are attached to the palmar plates of the MP, PIP and DIP joints respectively. During the digital movement, they retract approximately 50% of their length. The osseous pulleys as A2 and A4 are fixed over the lateral and palmar borders of the first and the second phalanx respectively. It is on these pulleys that the Omega plasty is practised. The operative procedure is simple. It consists on a periosteal dissection over the one lateral border of the phalanx. The liberation is undergone palmarly releasing the lateral attachment of the pulley. It respects the anatomical continuity of the pulley and its mechanical properties. Indeed, the continuity of the pulley is fully respected with the periosteal flap of the digital tube floor maintaining sufficient attachment to the pulley to resist to the flexor tendon forces. The level of the flexor tendon injury and the digit position during the initial trauma will determine the level of tendon resistance and where the pulley plasty must be made. If the flexor zone II injury occurred with the digit in an extension position, the tendon conflict appears with the A2 pulley, while it arises with the A4 pulley if the digit was in flexed position. The Omega plasty creates the ideal conditions for an optimal flexor tendon movement recovery. It is a simple and a reproducible procedure. It doesn't distort the mechanical properties of the pulley and the digital tube. We used this pulley Omega plasty fifteen times in twelve patients. In 60% of the cases, the injury concerned the dominant hand, and in 67% of the cases, it was a work accident. In eight of our cases, the omega plasty was done in emergency at the same time of flexor tendon repair, while in the other seven cases, the pulley Omega plasty accompanied the late flexor tendon repair forgotten during the initial trauma management. In ten cases, the plasty concerned the A4 annular pulleys, while in the other five cases, it concerns the A2 annular pulleys. Four cases necessitate a secondary tenolysis three months after the tendon repair. Two patients moved out and cannot be included in our results. On the thirteen-remainder cases, nine retrieved a full digital flexion particularly those who underwent digital tenolysis, while the other four cases retrieved a satisfying digital function in spite of the partial DIP flexion. In our hand, the pulley Omega plasty "Omega" becomes almost a systematic procedure in conjunction with the flexor tendon repair. It offers the ideal conditions for a tendon healing and a physiological flexor tendons motion recovery.