The Emergency Physician (EP) commonly encounters lacerations or trauma to the dorsum of the hand and forearm. The possibility of extensor tendon lacerations must be considered in evaluating these patients. A recent study found that tendon injuries in the hand and wrist occur at a rate of 33.2 injuries per 100,000 person-years, with extensor tendon injuries being the most common.1 Single, shallow lacerations account for 54.4% of the tendon injuries studied and the most common location is the long finger.1 The extensor mechanism of the hand and forearm is typically disrupted in association with penetrating trauma. Blunt trauma (e.g., sudden forced flexion) can result in injury to extensor tendons. Performing an extensor tendon repair is an important skill in the EP’s surgical armamentarium.
The diagnosis of an extensor tendon injury must be identified during the initial examination. The timing of the tendon repair is not a critical aspect of its management. Successful repair of extensor tendons may be accomplished within a 7 day window following the injury.2 Splint immobilization of the damaged tendon can produce a similar outcome to surgical reapproximation at some anatomic sites. Laceration of < 50% of any tendon in all zones that the patient can extend against resistance can be immobilized with early protected motion.3
Repair of an extensor tendon by an EP requires familiarity with the anatomy of the region and skill in the surgical technique. Complications of tendon repair are more frequently associated with flexor tendons. Follow-up studies of extensor tendon repairs reveal similar pitfalls and problems.4 Adhesions, loss of length, tendon rupture, Swan neck deformity, Boutonniere deformity, and diminished flexion can all complicate the repair of an extensor tendon.5
The anatomy of the extensor mechanism prevents tendon retraction far from the site of a laceration or partial disruption.6 This is mostly due to the tethering of tendons by multiple interconnections as tendons cross the dorsum of the hand. Tendons over the dorsum of the hand are ensheathed in a paratenon layer of tissue. This covering is extrasynovial and contains the cut ends of tendons in a tissue layer that prevents their wide separation. These properties frequently allow both ends of a lacerated extensor tendon to be located with local wound exploration.
The techniques for extensor tendon repair originate in studies of flexor tendons. The goal of extensor tendon repair is to restore tendon continuity and function while minimizing interference from the repair itself. The suture techniques of Kessler and Bunnell are two of the methods traditionally used in this repair. Modifications of these original methods have resulted in the greatest outcome measurements of tendon strength.7 Familiarity with these two suture techniques, knowledge of extensor tendon anatomy, and knowledge of surrounding structure anatomy is essential to the successful repair of any extensor tendon in the Emergency Department (ED).
ANATOMY AND PATHOPHYSIOLOGY