Traumatic arthritis

Traumatic arthritis is usually not the result of a single injury but of repeated and excessive pronation/supination movements. There is constant pain, aggravated by movement. Swelling may be seen at the ulnar side of the distal forearm. Treatment consists of one or two intra-articular injections of 10 mg of triamcinolone acetonide.

Arthrosis

When a fracture of the distal part of the radius fails to unite properly, arthrosis at the distal radioulnar joint may follow. Mal-union of the distal part of the ulna does not give rise to persistent problems⁵ and painless ulnar styloid non-union is a frequent incidental radiographic finding.⁶

The patient feels discomfort with movement of the joint. On examination, the extremes of both rotations are uncomfortable. The condition may be helped by strapping the distal part of the forearm; if this does not help, intra-articular triamcinolone may be tried.

Monoarticular steroid-sensitive arthritis

Arthritis may develop without a provable cause such as rheumatoid or traumatic arthritis. Furthermore, the condition will worsen when attempts are made to mobilize the joint. Such a condition responds particularly well to intra-articular triamcinolone.⁷

Rheumatoid arthritis

Rheumatoid arthritis (RA) involves the wrist in up to 95% of cases. The distal radioulnar joint is affected in 31–75% of these patients and is frequently the first compartment of the wrist involved,⁸ often bilaterally.⁹ Triamcinolone suspension injected intra-articularly once or twice a year may keep the joint free from symptoms.¹⁰

Long-standing rheumatoid arthritis results in ligamentous laxity. At the distal radioulnar joint this leads to the so-called ‘caput ulnae syndrome’: dorsal subluxation of the distal part of the ulna, supination of the carpus on the forearm, and palmar dislocation of the tendon of the extensor carpi ulnaris.^11–14

Limited supination

After a mal-united Colles’ fracture, shortening of the radius may be responsible for an irreversible limitation of supination only, with the end-feel of a bony block.^15,16 The movement may be painful in recent cases but should become painless in due course.

A dorsal dislocation of the ulna also presents with a block to supination and a visible dorsoulnar prominence. The mechanism for dorsal subluxation and dislocation is extreme pronation and extension, which pull the ulnar head out through the dorsal capsule. Triangular fibrocartilage complex avulsion and attenuation of the palmar radioulnar ligament will allow this dislocation.¹⁷

Painful supination

In tenosynovitis of the extensor carpi ulnaris, passive supination may be painful at the end of the range. This is a localizing sign, indicating that the lesion lies in the groove at the base of the ulna. The tenosynovitis will, of course, be diagnosed by interpreting resisted movements at the wrist (see p. 345).

Limited pronation

A block to pronation is present in palmar dislocations of the ulna. On inspection–palpation there will be a volar–ulnar prominence and a palpable radial sigmoid notch.¹⁸

Disorders of the triangular fibrocartilage complex

During the last few decades it has become obvious that triangular fibrocartilage complex (TFCC) tears are a common source of ulnar-sided wrist pain. The TFCC plays an important role in load bearing across the wrist, as well as in distal radioulnar joint stabilization.

Palmer devised a classification system of TFCC tears in 1989.¹⁹