Disorders of the lower radioulnar joint

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Disorders of the lower radioulnar joint



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Disorders of the inert structures


Pain felt at the wrist during pronation and supination movements of the forearm inculpates the distal radioulnar joint. The source can be the joint capsule,1 the ligaments24 or the articular disc.



Capsular pattern


The capsular pattern of the lower radioulnar joint presents with pain at the end of range of the two movements (pronation and supination, Fig. 22.1) and indicates arthritis. Usually there is only pain at end-range but sometimes there may be equal limitation, or slightly more limitation of supination than of pronation.







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





Technique: intra-articular injectionimage


The patient sits at the couch with the arm lying in pronation. A 1 mL syringe filled with triamcinolone acetonide and fitted with a 2 cm needle is used. The joint line, which is very short, is identified just radially to the head of the ulna. Gliding movements between the ulna and radius may help to find it. As the extensor digiti minimi tendon lies just dorsal to the joint line, care must be taken to avoid puncturing it (Fig. 22.2).



The needle is inserted vertically downwards at the midpoint of the joint line, about 5 mm proximal to the lower edge of the ulna. It is thrust down and will hit bone at about 1.5 cm. It is then manœuvred in an oblique direction towards the radius, until it slips beyond it without resistance. The injection is then carried out.



Non-capsular pattern






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

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Jun 5, 2016 | Posted by in ORTHOPEDIC | Comments Off on Disorders of the lower radioulnar joint
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