Radionuclide scintigraphy of femoral head specimens removed at arthroplasty for failed femoral neck fractures.

In order to determine the value of scintimetry as a tool for quantitative measurement of femoral head vascularity, the results of postoperative scintigraphic and histologic examination of surgically removed femoral head specimens were compared with those of preoperative radionuclide scintigraphy in 19 failed femoral neck fractures. Following intravenous administration of 600 MBq of Tc-99m MDP before hip replacement, the activity distribution in femoral head sections was recorded with a gamma camera and the area of isotope uptake calculated. A correlation was found between the results of preoperative noninvasive radionuclide scintigraphy and the assessment of isotope uptake in the removed femoral head specimens (r = 0.83, p less than .001) and was confirmed by the results of histologic examination. There is a risk, however, of overestimating the ratio of isotope uptake between the femoral head on the fracture side relative to the contralateral side with respect to quantitative assessment of femoral head vascularity, due to the general increase in isotope owing to accumulation in the injured hip region. The calculations, however, reflect the levels of radionuclide uptake and the varying degrees of femoral head vascularity.