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Joint Hand & Wrist

Wrist Ulnocarpal Complex

complexus ulnocarpalis

The ulnocarpal complex is the functional articulation between the distal ulna and the ulnar carpus (lunate and triquetrum), mediated through the triangular fibrocartilage complex rather than a direct bone-to-bone articulation. The articular disc of the TFCC, the ulnolunate and ulnotriquetral ligaments, and the meniscus homologue collectively transmit approximately 20% of axial load across the wrist from the ulnar carpus to the ulna. This load-sharing proportion varies with ulnar variance.

Region: Hand & Wrist
Clinical Relevance

Clinical Notes

The ulnocarpal complex is the site of ulnar-sided wrist pain in a broad range of conditions: TFCC tears, ulnocarpal impaction syndrome from positive ulnar variance, ulnolunate ligament injuries, and lunotriquetral instability. In positive ulnar variance, the ulna is longer relative to the radius and bears a disproportionately higher share of carpal load, producing chondral damage to the ulnar side of the lunate and proximal triquetrum. Ulnar shortening osteotomy rebalances load distribution and is the surgical treatment for symptomatic ulnocarpal impaction.

Pathology

Common Injuries & Conditions

Ulnocarpal Impaction Syndrome

Positive ulnar variance causes the ulnar head and ulnocarpal complex to bear excessive axial load, producing chondromalacia of the lunate ulnar facet, TFCC tears, and lunotriquetral ligament injury, managed with arthroscopic debridement and ulnar shortening osteotomy to offload the ulnar side.

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