An association between lunate morphology and scaphoid–trapezium–trapezoid arthritis

Abstract

The purpose of this study was to determine if an association exists between scaphoid–trapezium–trapezoid arthritis and lunate morphology. Plain neutral posteroanterior radiographs were evaluated for 48 patients with STT arthritis and 96 patients from a control group. Lunate type was determined using capitate–triquetrum (C-T) distance. A type I lunate was defined as a C-T distance ≤2 mm. A type II lunate was defined as a C-T distance ≥4 mm. Lunate type was recorded and compared between those with STT arthritis and a control group. The groups were similar with regard to age, gender and handedness. Type II lunates were found in 83% of cases with STT arthritis and in 64% of controls. STT OA was associated with type II lunate wrists (P = 0.02; OR = 0.35; CI: 0.15–0.82). We postulate that variations in scaphoid motion secondary to lunate morphology may contribute to the development of STT OA.