Prediction Value of SPECT/CT in Avascular Necrosis of Femoral Head After Femur Neck Fracture

Introduction: The aim of this study was to determine the diagnostic value of single-photon emission computed tomography/computed tomography (SPECT/CT) in prediction of avascular necrosis (AVN) after femoral neck fracture and to evaluate whether photon defect in femoral head as seen in SPECT/CT can be an index for choice of surgical method. Methods: This study was based on 97 patients who took SPECT/CT after femoral neck fracture from November 2012 to November 2017, with 64 patients with femoral intertrochanteric fracture in which chances of AVN is rare as a comparison group. Among 97 patients with femoral neck fracture, osteosynthesis was conducted in 7 patients with less than 15% of photon defect in damaged femoral head and 7 patients who wanted osteosynthesis, despite photon defect more than 15%, and 83 patients with photon defect more than 25% had arthroplasty. Patient with osteosynthesis was followed up with AVN by conducting magnetic resonance imaging (MRI) in 1 year after the surgery. Results: Quantitative analysis of SPECT/CT in 14 patients who had femoral neck osteosynthesis showed that 7 patients with femoral neck fracture showed photon defect of 15% or more, but less than 25% and 3 patients in these were diagnosed with AVN after 1-year follow-up by MRI. Sensitivity and specificity of SPECT/CT in predicting AVN was 100% and 63.6%, respectively, with prediction accuracy of 71.4%. Among 14 patients with femoral neck fracture who had osteosynthesis, photon defect in 3 patients diagnosed with AVN was 19.6% 5.2%, but photon defect in 11 patients who was not diagnosed with AVN was 10.7% +/- 5.2%, showing statistically significant difference between 2 groups (P = .001). Conclusion: Single-photon emission computed tomography/CT in patients with femoral neck fracture is considered to have diagnostic value in predicting occurrence of AVN, and percentage of photon defect is considered to be an useful index in determining the operative method.