Correlation of radiographic measurements with biomechanical test results

The refracture of bone after the removal of an internal fixation device is not common, but it can be a serious complication. The development of a simple radiographic tool to determine the condition of a healing bone would be of clinical importance. As a basis to developing this tool, it was important to determine whether a correlation exists between radiographic results and the stiffness index of bones during fracture healing. This experimental investigation in beagles showed that at 24 weeks after a unilateral femoral osteotomy, plain radiographs could be used to determine the stiffness index of healing bone. The results showed the cortex to callus ratio (the thickness of the cortex, including the periosteal callus, normalized by the thickness of the cortex of the bone not surgically treated) correlated positively with the stiffness index of the bones. This measurement might be useful in the clinical assessment of fracture healing. From a clinical point of view, caution is recommended after the removal of fracture plates when the cortex to callus ratio is low because such a low ratio may be associated with a low stiffness index of the healing bone. This information allows clinicians to adapt the postoperative regimen accordingly.