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Scaphotrapezoid-Trapezium Joint

articulatio scaphotrapezoidea et scaphotrapezii

The scaphotrapezoid-trapezium (STT or triscaphe) joint complex is the articulation between the distal scaphoid (scaphoid waist and distal pole) and the trapezium and trapezoid carpal bones. These three joints form a functional unit — the triscaphe joint — that moves as a unit during wrist motion. STT arthritis (pantrapezial arthritis) is a progressive degenerative condition often associated with first CMC joint OA.

Region: Hand & Wrist

Clinical Relevance

Clinical Notes

STT joint arthritis produces radial wrist pain and tenderness at the scaphotrapezial-trapezoid junction, often difficult to distinguish from radiocarpal or CMC joint arthritis without specific injection testing. CT demonstrates joint space narrowing, sclerosis, and osteophyte formation at the STT complex. Corticosteroid injection into the STT joint under fluoroscopy confirms the joint as the pain source. Surgical options for STT arthritis include STT arthrodesis (triscaphe fusion), which limits wrist dart-throwing motion but relieves pain, and arthroplasty with silicone or pyrocarbon implant.

Pathology

Common Injuries & Conditions

Pantrapezial Arthritis Involving STT and First CMC Joints

Combined degeneration of the STT joint and the first CMC joint produces radial wrist and thumb base pain in older patients; fluoroscopic injection testing separating the two joint compartments identifies the dominant pain generator; STT fusion combined with first CMC arthroplasty addresses both components in patients who fail conservative treatment.