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 simp le radiographic tool to determine the condition of a healing bone would be of clinical importance. As a basis to developing this tool, it was importan t to determine whether a correlation exists between radiographic results an d the stiffness index of bones during fracture healing. This experimental i nvestigation 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 thickn ess of the cortex, including the periosteal callus, normalized hy the thick ness of the cortex of the bone not surgically treated) correlated positivel y with the stiffness index of the bones. This measurement might be useful i n the clinical assessment of fracture healing. From a clinical point of vie w, caution is recommended after the removal of fracture plates when the cor tex 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 clinicia ns to adapt the postoperative regimen accordingly.