The occasional extensor tendon laceration repair

Rural physicians commonly have patients present to the emergency department with injuries to the hand. Occasionally, these injuries involve extensor tendons. Extensor tendon injuries are more common than flexor tendon injuries, due largely to the fact that extensor tendons are less protected and are more superficially located. The strategy used to manage an extensor tendon injury varies with the location of that injury. For this reason, optimal management of a hand extensor tendon injury requires an understanding of extensor tendon anatomy and function. The other principle regarding extensor tendon injuries is that these injuries should not be underestimated. Care and attention during initial treatment is an important aspect of ensuring good outcome, or at least to minimize deformity. This article reviews extensor tendon anatomy and terminology, and then reviews briefly the management of hand extensor tendon injuries with a focus on repair of lacerated tendons. The 5 muscles that are involved in actually extending the fingers are the extensor pollicis brevis, extensor pollicis longus, extensor indicis propnus, extensor digiti minimi, and extensor digitorum cornmums (Fig. 1). The extensor pollicis brevis muscle extends the thumb at the MCP, and the extensor pollicis longus extends the thumb at the interphalangeal joint. The extensor indicis proprius muscle extends the index finger, the extensor digiti minimi extends the little (fifth) finger, and the extensor digitorum communis is involved in extending all digits except for the thumb. The A extensor digitorum communis tendons share a common muscle origin, which explains why fingers tend to extend together. The tendon of extensor digitorum communis to the little finger is missing m more than 50% of people and is replaced by a the fibrous sheath from the ring finger extensor originating just proximal to the MCP joint. Similar fibrous sheaths connect other tendons of the extensor digitorum to one another. These fibrous sheaths are referred to as juncturae tendinum. They are the reason why one can lacerate a tendon of the extensor digitorum communis muscle proximal to the MCP joints and still see extension of the involved digit distal to the laceration. The extensor tendons of the extensor digitorum commums muscle inserts at multiple sites, including the base of the proximal, middle and distal phalanges. Halfway down the proximal phalanx the extensor tendons of this muscle trifurcate into a central "slip" and i