Introducing the “SOAC Wrist”: Scaphotrapeziotrapezoid Osteoarthritis Advanced Collapse

Despite being the second most common osteoarthritis of the wrist, little is known about scaphotrapeziotrapezoid osteoarthritis. Not all patients with this type of osteoarthritis have symptoms, and, even in those symptomatic patients, the intensity of the complaint is not proportional to the severity of the degeneration. In symptomatic patients, when the conservative treatment fails, grading classifications to help define the surgical treatment are solely based on the joint characteristics, and fail to assess the rest of the carpus.

In general, most carpal degenerative processes show the same evolution pattern, which varies according to the initial injury, along with the type of deformity and the inherent instabilities. Thus, we hypothesize that the degenerative evolution due to primary osteoarthritis of the scaphotrapeziotrapezoid joint also follows a logical evolutionary sequence, similar to the one that occurs in cases of scapholunate advanced collapse (SLAC), scaphoid nonunion advanced collapse (SNAC), scaphoid malunion advanced collapse (SMAC), and scaphoid chondrocalcinosis advanced collapse (SCAC), thus resulting in scaphotrapeziotrapezoid osteoarthritis advanced collapse (SOAC). We have divided the SOAC into three groups, and considered that their treatment shall be guided by the evolutionary stage of the disease, and not by the surgeon's preferred technique.

Evaluation and Management of Scaphoid-Trapezium-Trapezoid Joint Arthritis

Degenerative arthritis at the articulation of the scaphoid, trapezium, and trapezoid (STT or triscaphe joint) is a common degenerative disease of the wrist. Pain and weakness with grip strength reduction and functional limitations when performing routine daily tasks are common complaints of patients with STT arthritis. Initial conservative treatments for STT arthritis include splinting, bracing, activity modification, anti-inflammatory medication, and steroid injections for pain relief. Failure of conservative treatment is the main indication for surgery, which may include distal scaphoid excision, with or without filling of the void after excision, trapeziectomy, STT arthrodesis, or STT implant arthroplasty.

A WORKING CLASSIFICATION FOR THE MANAGEMENT OF SCAPHO-TRAPEZIUM-TRAPEZOIDOSTEO-ARTHRITIS

Osteo-arthritis (OA) of the scapho-trapezium-trapezoid joint (STT) is the second most common involved joint after trapezium-metacarpal I OA in the wrist.

The possible aetiology causing or contributing to the development of STT OA is shortly discussed.

A working classification is then proposed, which assists in the management of STT OA.