Orthopaedic surgical approaches 2022, Nov, 21 | 12:00 am

Applied Surgical Anatomy of the Dorsal Approach to the Wrist

Applied Surgical Anatomy of the Dorsal Approach to the Wrist

 

 

Overview

 

Twelve tendons cross the dorsal aspect of the wrist joint and pass beneath the extensor retinaculum, which is a thickening of the deep fascia of the forearm. The extensor retinaculum prevents the tendons from “bowstringing.” Fibrous septa pass from the deep surface of the retinaculum to the bones of the forearm, dividing the extensor tunnel into six compartments. These septa must be separated from the retinaculum so that each compartment can be opened in surgery (see Fig. 5-11).

 

Landmarks and Incision

Landmarks

Two bony landmarks lie on the dorsal aspect of the wrist. The styloid process is the distal end of the lateral side of the radius. It also is the site of attachment of the tendon of the brachioradialis muscle. Its medial part articulates with the scaphoid bone (see Fig. 5-14A). Strong and sudden radial deviation of the wrist may cause the radial styloid process to slam into the scaphoid and fracture it (see Fig. 5-14B). Alternatively, such a force may cause a fracture of the radial styloid.

The styloid process often is excised when the scaphoid fails to unite or after arthritic changes in the wrist joint have affected the radial margin of the radioscaphoid joint. This procedure may be carried out in conjunction with a scaphocapitolunate arthrodesis.8

Lister tubercle (the dorsoradial tubercle) is a small bony prominence on the dorsum of the radius. The tendon of the extensor pollicis longus muscle angles around its distal end, changing direction about 45 degrees as it does so. When the wrist is hyperextended, the base of the third metacarpal comes very close to Lister tubercle, and the two bones can crush the trapped tendon of the extensor pollicis longus. This probably is the reason the tendon suffers delayed rupture in some cases of minimal or undisplaced fractures of the distal radius; the tendon sustains a vascular insult at the time of the original injury, even though it remains intact (see Fig. 5-14C).6

Incision

Longitudinal incisions crossing the lines of cleavage of the skin almost perpendicularly on the dorsum of the wrist can cause broad scarring. Nevertheless, because the skin on the wrist is so loose, this is one of those rare occasions when a skin incision can cross a major skin crease at right angles without causing a joint contracture.

 

Superficial and Deep Surgical Dissection

 

The extensor retinaculum is a narrow (2-cm) fibrous band that lies obliquely across the dorsal aspect of the wrist. Its radial side is attached to the anterolateral border of the radius; its ulnar border is attached to the pisiform and triquetral bones. (Were it attached to both bones of the forearm instead, pronation and supination would be impossible, because its fibrous tissue is incapable of stretching the necessary 30%.)

Fibrous septa pass from the deep surface of the extensor retinaculum to the bones of the carpus, dividing the extensor tunnel into six compartments (Fig. 5-12). From the radial (lateral) to the ulnar (medial) aspect, the compartments contain the following:

 

 

 

Figure 5-12 Anatomy of the distal forearm, with the extensor retinaculum excised and the septa remaining. The retinaculum on the ulnar side inserts into the

triquetrum and pisi form bones.

 

  1. Abductor pollicis longus and extensor pollicis brevis. These tendons lie over the lateral aspect of the radius. They may become trapped or inflamed beneath the extensor retinaculum in their fibroosseous canal, producing de Quervain disease (tenosynovitis stenosans). Access to this compartment is required to apply plates to the radial column of the wrist joint.

  2. Extensor carpi radialis longus and extensor carpi radialis brevis. These muscles run on the radial side of Lister tubercle before reaching the dorsum of the hand. The tendon of the extensor carpi radialis longus is used frequently in tendon transfers. The tendons run in separate synovial sheaths.

  3. Extensor pollicis longus. This tendon passes into the dorsum of the hand on the ulnar side of Lister tubercle. It may rupture in association with fractures or rheumatoid arthritis. The oblique passage of this tendon on the dorsal aspect of the wrist creates significant problems for plate fixation of fractures of the distal radius. Tendon irritation and even rupture may occur due to abrasion of the tendon on the surface of the plate. Similar problems apply to a lesser degree with all the other extensor tendons.9

  4. Extensor digitorum communis and extensor indicis. The indicis tendon is used commonly in tendon transfers.

  5. Extensor digiti minimi. This tendon overlies the distal radioulnar joint.

  6. Extensor carpi ulnaris. This tendon passes near the base of the ulnar styloid process. It is used sometimes in tendon transfers (Fig. 5-13; see Fig. 5-12).

     

     

    Figure 5-13 The extensor tendons have been removed, revealing the dorsal radiocarpal ligament. The radial artery is seen piercing the first dorsal interosseous muscle and contributing to the dorsal carpal rete. Note the hood mechanism for the index finger; contributions are made to it by the first dorsal interosseous and the first lumbrical muscles.

     

     

    Figure 5-14 A: Dorsal aspect of the bones of the distal forearm, wrist, and proximal hand. B: A strong and sudden radial deviation of the wrist may cause the radial styloid process to impinge on the scaphoid tubercle and fracture it. C: With sudden extreme dorsiflexion of the wrist, as when one falls on an outstretched hand, the extensor pollicis longus tendon may be trapped or crushed between the dorsal radial tubercle (Lister tubercle) and the base of the third metacarpal.