Prevalence of accessory carpal ossicles – a CT-based survey

This observational study aimed to determine the prevalence of accessory carpal ossicles (ACO) using a computerized tomography examination. The digital imaging database of the authors’ institution was retrospectively reviewed, and all wrist computerized tomography examinations for any indication were identified between 2014 and 2021. Patients with previous wrist surgery and severely impaired carpal anatomy, such as severe osteoarthritis or congenital or acquired deformities that may preclude evaluation and identification of accessory carpal ossicles, were excluded from the study. Four orthopedic surgeons reviewed the computerized tomography scans and identified patients with accessory carpal ossicles on two-dimensional (coronal, axial, and sagittal planes) and three-dimensional computerized tomography reconstructions. Two thousand two hundred thirteen patients, with a mean age of 36.8±12.8 years, were identified and included. Accessory carpal ossicles were detected in 156 (7.1%) subjects, with 186 ACOs identified. The most common accessory carpal ossicles were os praetrapezium (n:34, 1.536%), os triquetrum secundarium (n:28, 1.265%), os epitriquetrum (n:20, 0.903%), os hamuli proprium (n:18, 0.813%), os ulnostyloideum (n:16, 0.723%), os epilunatum (n:12, 0.542%) and os styloideum (n:11, 0.497%) respectively. The study provides valuable information on the prevalence and distribution of accessory carpal ossicles, which can aid in accurately diagnosing and managing wrist pathologies. Further research is warranted to explore the clinical significance and potential impact of rare accessory carpal ossicles on wrist disorders.