Abstract
BACKGROUND: Successful trapeziometacarpal (TM) joint arthroplasty depends heavily on bone quality, particularly of the trapezium, where cup loosening remains a leading cause of implant failure. While dual-energy x-ray absorptiometry measures bone mineral density (BMD), it lacks regional specificity. Computed tomography (CT)-derived Hounsfield units (HU) offer quantitative, site-specific bone density estimation and may serve as a surrogate for BMD in preoperative planning. This study investigated the relationship between CT-derived HU values and tactilely perceived bone hardness of the trapezium to evaluate HU as a reliable predictor of bone quality. METHODS: Ten embalmed Body Donor hands were scanned using a Philips Spectral CT 7500 scanner. Bone segmentation and density analyses were conducted in 3D Slicer software, focusing on trabecular regions of the trapezium (proximal, ridge, and submetacarpal) and the first metacarpal (proximal, medial, and distal). Hounsfield unit values were converted to density (g/cm(3)) using validated equations. An experienced anatomist assessed trapezium hardness ("soft" or "hard") using bone forceps. Correlations between HU values, bone volume, and perceived hardness were analyzed using Pearson correlation coefficient. RESULTS: The mean trapezium HU was 354 (682.88 g/cm(3)), with regional trabecular variation: proximal 160.7 HU, ridge 286.5 HU, submetacarpal 241.7 HU. The first metacarpal demonstrated broader density variation (-285.8 to 228.8 HU). Hounsfield unit values correlated significantly with perceived hardness (r = .71, P = .02), whereas bone volume showed no correlation (r = .08, P = .82). Male trapezia displayed higher HU and density (472.7 ± 89.8 HU; 740.9 ± 44.0 g/cm(3)) than females (436.1 ± 87.2 HU; 723.0 ± 42.7 g/cm(3)). CONCLUSIONS: Computed tomography-derived HU values strongly correlate with perceived bone hardness and provide an objective surrogate for assessing bone quality in TM joint arthroplasty. Incorporating preoperative HU assessment may guide implant selection and fixation strategies, reducing trapezium cup loosening and implant failure.