Fracture stiffness in callotasis determined by dual-energy X-ray absorptiometry scanning

Assessing healing after distraction limb lengthening is essential to manage patients undergoing callotasis for leg lengthening or bone transport. Dire ct measurement of fracture stiffness can assess healing but the equipment m ay not be available. In addition, it requires removal of the fixator, which may be complicated for ring fixators. The present study investigates wheth er an equivalent measure of healing can be based on the mineral density pat tern from dual-energy X-ray absorptiometry (DXA) scans. Nine consecutive pa tients undergoing callotasis were studied. Bending stiffness of the distrac tion segment was measured and DXA scans were performed regularly starting 6 weeks after completing distraction. In all, 23 simultaneous readings of be nding stiffness and DXA scans were obtained. All density patterns showed a distinct minimum value of bone mineral density. We found a high and signifi cant correlation between fracture bending stiffness and the square of the t otal mineral content at the location of minimum bone density (r(2) = 0.77, P < 0.001). We conclude that DXA scans can be used reliably and effectively to determine fracture bending stiffness, valuable for determining both tim e of frame removal and delay in union.