Tendinosis and Tenosynovitis of the Extensor Tendons

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  Stenosing tenosynovitis (tenosynovitis) of the first extensor compartment is referred to as de Quervain disease. The approximately 2cm-long osteoligamentous tunnel of the first extensor compartment is formed by an osseous groove in the radial styloid process and the overlying extensor retinaculum. Stenosing Stenosing tenosynovitis is a result of overuse of the extensor pollicis brevis and abductor pollicis longus tendons, which pass through the first extensor compartment. It is characterized by an isolated, painful inflammation of the tenosynovium proximal to the tabatière (anatomical snuff-box) near the radial styloid process. The early stage is characterized by an unspecific swelling, later developing into a thickened extensor retinaculum, which narrows the tendon compartment and reduces the ability of the tendon to glide smoothly. Finkelstein’s test is positive (pain above the first extensor compartment during passive wrist ulnar deviation with a closed fist). Frequently tendinosis is also found ( Fig. 29.1 ). The clinical symptoms progress with the self-maintaining process.

  
  
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  Tenosynovitis of the second extensor compartment containing the tendons of the extensor carpi radialis longus and brevis muscles is rare ( Fig. 29.2 ). More frequently, however, is the intersection syndrome of the extensor pollicis brevis (EPB) and abductor pollicis longus (APL) muscles, which may be misinterpreted as tenosynovitis of the second tendon compartment. The intersection syndrome is a friction syndrome of the EPB and APL 4–8cm proximal to the wrist, where both muscles obliquely traverse and intersect with the extensor carpi radialis longus and brevis tendons. This syndrome is common in individuals who row, lift weights, or paint.

  
  
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  In the third extensor compartment containing the extensor pollicis longus tendon, tenosynovitis develops relatively often after repetitive activities such as playing drums or secondary to wrist trauma such as distal radius fractures. The condition is rarely painful andmay lead to a spontaneous rupture of the tendon.

  
  
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  In the fourth extensor compartment consisting of the extensor indicis and extensor digitorum tendons, general tenosynovitis of all tendons ( Fig. 29.3 ) is less often observed than an extensor-indicis syndrome of the index finger. Since about 75% of the belly of the extensor indicis muscle lies within the fourth tendon compartment and numerous variants exist, this type of inflammation is somewhat more common.

  
  
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  Tenosynovitis of the tendon of the extensor digiti minimi muscle in the fifth extensor compartment is rare.

  
  
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  The sixth extensor compartment with the extensor carpi ulnaris (ECU) tendon is often affected. In this compartment, the extensor retinaculum contributes little to the stability of the tendon; instead, an osteofibrous tunnel formed by the ulnar styloid process, a bony groove in the ulna head, and an additional fibrous membrane maintain the position of the ECU tendon during wrist motion. This constellation predisposes to a tendinous ECU tunnel syndrome in the presence of tendinosis and tenosynovitis. With severe tenosynovitis, concomitant inflammatory reactions on the ulnar styloid process and the ulnocarpal complex can appear ( Fig. 29.4 ). If the osteofibrous unit is injured, repeated subluxations of the tendons are observed.

Tendinosis and Tenosynovitis of the Flexor Tendons

The flexor carpi ulnaris (FCU) and flexor carpi radialis (FCR) tendons are most often affected at the level of the wrist. Dependently of exertion, the flexor tendons of the fingers can be involved in groups or individually ( Figs. 29.5 , 29.6 ).

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  The FCU tendon is affected either as an insertional tendinosis near the pisiform and hamate and metacarpal V or as tenosynovitis at the level of the wrist ( Fig. 29.7 ). Common causes are repetitive flexion movements of the wrist, as in tennis.

  
  
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  The FCR tendon traverses in a separate osteofibrous compartment within the carpal tunnel before insertinginserting at the bases of the second and third metacarpals. It courses over the scaphoid tubercle and then passes through the sulcus of the trapezium. Therefore, distal scaphoid fractures and scaphotrapeziotrapezoid (STT) osteoarthritis ( Fig. 29.8 ) play a causative role in tendinosis and tenosynovitis, as does primary overuse.

  
  
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  A special form of tendinosis and tenosynovitis of the flexor tendons is the trigger finger/thumb. This condition is characterized by blockage of a flexor tendon due to an absolute or relative stenosis of the tendon sheath. When this stenosis is overcome with increasedforce, the characteristic triggering of the affected finger occurs during flexion or extension. In an advanced stage of disease, the narrowing can no longer be overcome, and the affected finger remains fixed in a flexed or extended position. Pathogenetically, there is a stenosing tenosynovitis at the predisposed site at the level of the A1 anular ligament. The acquired form usually appears after the age of 50 years and is associated with a thickening of the tendon and/or its sheath. It is caused by degenerative changes or intermittent overuse. In the rarer congenital form in infants or small children, the thumb is usually affected. There is either no pain or pain only during the snapping movement. The diagnosis is made clinically. Imaging procedures are required only to clarify particular clinical objectives.