Technetium-99m-methylenediphosphonate scintimetry after femoral neck fracture. A three-year follow-up study.

Thirty-nine patients with femoral neck fractures were followed up clinically and radiographically by technetium-99m-methylenediphosphonate (99mTc-MDP) scintimetry two to 20 days and four, eight, 12, 24, and 36 months after surgery or until redisplacement, pseudarthrosis, or segmental collapse occurred. The scintimetric data were calculated by selecting regions of interest on the fractured and intact sides over the femoral head, neck, greater trochanter, and shaft; ratios of fractured/intact side were obtained for each region. Bone metabolism after femoral neck fracture was expressed and analyzed numerically. Prognosis regarding the course of healing could be made with precision by studying femoral head isotope activity shortly after surgery, preferably one to three weeks after operation. Intact femoral head uptake (ratio greater than 1.0) was connected with uneventful healing, while defective uptake (ratio less than 1.0) was observed with healing complications. The vast majority of femoral heads with primary uptake defects showed increased uptake (greater than 1.0) after four months, often as early as six to eight weeks, indicating revascularization. Segmental collapse, as well as redisplacement and pseudarthrosis, appear to be related to femoral head vascular injury. Femoral head uptake in patients in whom healing complications developed secondary to avascularity differed significantly from that in patients with normal healing, except at investigations performed four to eight months after operation. 99mTc-MDP uptake in the femoral neck, trochanter, and shaft areas was increased for all femoral neck fractures. Subsequent normalization was considerably slower in patients with healing complications. A significant difference from normal healing did not occur until 12-24 months after operation. For patients with contralateral hip disease affecting the femoral head ratio, the prognosis regarding complications was made with the aid of the femoral head/shaft ratio on the fracture side.