Distal Radius Dual-Energy X-ray Absorptiometry and Second Metacarpal Dimensions Predict Carpal Bone Morphology

Abstract Complications during wrist surgery may be related to poor bone quality. The goal of this study was to determine if radiographic assessment of upper extremity bone quality reflects the trabecular bone quality of carpal bones, as this could be used clinically to assess adequacy for carpal bone surgical fixation or reconstruction. The first goal was to determine the carpal trabecular bone volume fraction (bone volume/total volume; BV/TV) in capitates, lunates, and scaphoids using micro-computed tomography (micro-CT). A second goal was to determine if either ultradistal radius bone mineral density (UDBMD) or second metacarpal cortical percentage (2MCP) is related to the trabecular BV/TV in carpal bones. For 20 fresh-frozen cadaver forearms, dual-energy X-ray absorptiometry (DXA) measured UDBMD. X-rays were used to measure the cortical thickness and periosteal diameter of the second metacarpal for calculation of 2MCP (% cortical thickness/periosteal diameter). Capitates, lunates, and scaphoids were scanned using micro-CT to assess carpal cancellous bone BV/TV. To determine if UDBMD and 2MCP were predictors of BV/TV after accounting for the influence of age and sex, the contribution of each was compared using semipartial correlation coefficients (SPCC) in two multiple linear regression models. UDBMD, 2MCP, and age each correlated individually with the carpal BV/TV (R = +0.84, +0.74, and −0.66, respectively). When accounting for the influence of age and sex, the regression models demonstrated that 2MCP was not a significant predictor of BV/TV (SPCC = +0.257, p = 0.10) but that UDBMD was (SPCC = +0.40, p = 0.004). Both UDBMD and 2MCP correlate with BV/TV individually, but only UDBMD correlates with BV/TV after accounting for age and sex. This study serves as a first step in determining whether forearm DXA and/or 2MCP may be used as screening tools to predict surgical fixation outcomes in the wrist.