Extensor tendon injuries: a new classification, strong repairs, and easier therapy

Summary: A new 5-zone classification of extensor tendons in the hand and forearm is proposed to regroup surgical methods and to discuss outcomes. Similar to flexor tendon zones, the new classification unifies the zones of fingers and thumbs. Based on this classification, strong surgical repairs (6-strand repairs) are always used for zone 2. In zone 1c and 3, 6- or 4-strand, or other repair methods are used. The finger is protected with short splinting with early active motion or hand use. Many principles of flexor tendon repairs are applicable to these areas of extensor tendons. A strong solid repair in fact abolishes the need of postoperative splint protection, but the splinting serves to avoid inadvertent hand use or injury. A short finger splint or a relative extension splint can be used. Tendons in zone 4 and 5 are repaired with strong repair methods, such as 4- or 6-strand repairs, followed by postoperative early active motion, but they often need secondary tenolysis. Zones 1a and 1b injuries remain the most baffling, often with late problems. A relative flexion splint may cure closed zone 1b injury, but complicated open zone 1b injury often leads to late difficult problems. In the thumb, a 6-strand repair is commonly used to repair the extensor tendons and a long splint is necessary for protection because of the large force over the thumb. The author calls for validation of this new zone classification and simpler treatment approaches based on strong surgical repairs followed by looser protection, active digital motion and hand use.