The Clinical Implications of Scaphotrapezium-Trapezoidal Arthritis With Associated Carpal Instability

Patients with STT arthritis may present with carpal instability that is not related to radiographic scapholunate instability. This instability is characterized by a normal scapholunate angle with an extension stance of the scaphoid and lunate. Midcarpal arthritis may be present. Surgical intervention for patients with STT arthritis and DISI deformity may lead to radiographic progression of midcarpal instability.