Outline

The history of dealing with this problem started with the earliest attempts at primary flexor tendon repair and continues to the present time. When Kleinert and colleagues published their successful primary tendon repairs in zone 2 combined with early motion in 1973, he initially resected a window of tendon sheath.¹ Ten years later, Lister and coworkers advocated closure of the tendon sheath following a limited, pulley preserving tendon exposure.² In 1983, they advocated complete closure of the sheath so that catching of the repair on an edge of sheath would be avoided, and in 1985 Lister described replacing a deficient sheath with a fascial graft to accomplish closure.^3,4 However, others realized that tight sheath closure might restrict the free gliding of the sutured tendons.^5,6

This author first used the procedure of pulley enlargement in 1985 for a patient whose bulky tendon repair would not glide into or through the A4 pulley. Contrary to the dictum of A2 and A4 pulley preservation, the entire A4 pulley was cut. Because of concern that bowstringing could result, the A4 pulley was repaired with a slight enlargement using a fascial graft as Lister recommended for a deficient sheath. This seemed to solve the problem of providing a nonrestrictive gliding environment for the repair while adequately restoring important sheath support. The result of that surgery was surprisingly good. Since then this technique has been applied to either the A2 or A4 pulleys in a total of 12 fingers in 9 patients, which represent the more difficult patients treated over a 20-year period.⁷

Since those developments early in the history of primary repairs of flexor tendons, attention and research have made tendon repairs stronger to prevent rupture if subjected to increased resistance. Stronger repairs are often more bulky and can make gliding even more difficult and catching more likely. Even the strongest repair might rupture if an exposed edge of pulley that completely blocks motion is encountered.⁸ Venting has become an accepted method of sheath management, being a way to preserve enough of the essential pulleys while improving tendon gliding. Venting allows free gliding to occur only within the vented area, and the repair must often reenter a tight, restrictive sheath, exposing the repair to catching on an edge of sheath or to traversing an area of resisted gliding.

Other methods that have been suggested to solve the same problem include removal of one slip of flexor digitorum superficialis (FDS), pulley enlargement by V-Y plasty, and pulley release from the underlying phalanx.^7,9–18 Tang and colleagues have shown complete pulley incision with or without graft repair in chickens reduces work of flexion even after the effects of time and healing are included.^12,19,20 Tang^8,11 and Elliot¹⁰ have even recommended completely cutting the A4 pulley as standard clinical practice despite the continuing belief that at least some of the A2 and A4 pulleys are essential to preventing bowstringing and preserving the efficiency of finger flexion.

Because of the encouraging results in the clinical patients, during the past 5 years laboratory investigations have been conducted to explore how this technique affects gliding within the enlarged sheath, triggering, and bowstringing. These are summarized below along with the surgical technique and the clinical outcomes.

Surgical Technique

Operative Techniques

The flexor tendon sheath is exposed and examined with the finger in full extension. Tendon and sheath injuries are evaluated and the anticipated excursion of the repaired tendon is identified. If the flexor digitorum profundus (FDP) lies within the A4 pulley or if both tendons might have to pass under the A2 pulley, sheath and pulley enlargement might be needed, and the sheath, including any part of a pulley, is opened far enough to provide adequate exposure for easy tendon repair. The sheath injury is extended distally until, with the help of distal interphalangeal joint flexion, a core suture can be placed in the FDP stump. The sheath/pulley incision is placed lateral to the volar midline, leaving enough sheath tissue to secure a suture and adjusting the incision to fit the conditions of the original injury. The distal FDS is always longer than the FDP and readily visible with this exposure. The proximal tendons are retrieved. If needed, the proximal sheath/pulley is incised far enough to allow room so that an easy tendon repair can be performed. Both tendons are repaired.

In the series, all tendons or tendon slips were repaired with a two-strand modified Kessler repair using 3-0 suture. The suture was performed starting in the distal tendon segment with a 1-cm longitudinal insertion and a locking loop followed by the transverse pass and a grasping loop leading back to the tendon end. The identical pattern was used in the proximal tendon segment. This allowed easy tensioning until the ends abutted without bunching and there was no gapping when placed under manual tension. The triple-throw surgeon’s knot was buried inside the repair. All repairs were reinforced and smoothed with a circumferential running, alternately locked, 6-0 nylon suture, making 10 to 12 passes around each tendon and 6 to 8 passes around each tendon slip. The 6-0 suture was tied with one triple-throw square knot on the external lateral tendon surface. A stronger repair can be substituted if preferred.

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Flexor Tendon Injuries in Children Treatment of the Flexor Tendon Sheath and Pulleys Tendon Friction, Lubrication, and Biomechanics of Motion Staged Tendon Grafts and Soft Tissue Coverage Outcomes of Flexor Tendon Repairs and Methods of Evaluation Customizing Flexor Rehabilitation Based on Zone or Type of Injury

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