Dual-energy x-ray absorptiometry as a measure of healing in fractures treated by intramedullary nailing

The conventional qualitative techniques of manual manipulation and plain radiography do not give a quantifiable measurement of fracture healing. With internal fixation, manual manipulation is not usually possible, and conventional radiographs may not give much useful information, particularly if only a small amount of callus is formed. Dual-energy x-ray absorptiometry (DXA) provides an accurate method of quantifying the changes in bone mineral density (BMD) which occur during fracture healing. Preliminary work showed that the presence of a highly attenuating metal implant in the scan area did not affect the reliability of BMD data obtained from scans. On this basis, we have assessed the use of DXA in the clinical situation to monitor fractures treated by intramedullary nailing. Five fractures of the mid-shaft of the tibia stabilized by interlocked intramedullary nails have been monitored by DXA at monthly intervals through healing. DXA improves on radiography in giving a quantitative measure of fracture site mineralization. However, it is concluded that, because of the relatively small changes in callus BMD encountered with the rigid fixation provided by interlocked intramedullary nailing, DXA offers no significant diagnostic advantages over plain radiography.