Quantitative Characterization of Bone Viability of Femoral Head and Subchondral Bone by Using Single Photon Emission Computerized Tomography/Computerized Tomography (SPECT/CT)

BACKGROUND Vascularized fibular grafting (VFG) has been successfully employed for treating avascular necrosis of the femoral head (ANFH). In this study, we aimed to evaluate the bone viability of the femoral head and subchondral bone following VFG by using single photon emission computerized tomography and computerized tomography (SPECT/CT). MATERIAL AND METHODS Between March 2011 and June 2014, 14 ANFH patients (17 hips) treated with VFG at Zhongshan Hospital, Fudan University, were prospectively enrolled. The patients included 9 males and 5 females with an average age of 26.6 years (range, 18-34 years). According to the ARCO (Association Research Circulation Osseous) stage criteria, 3 hips corresponded to stage IIA, 4 hips to stage IIB, 2 hips to stage IIC, 5 hips to stage IIIA, and 3 hips to stage IIIB. A novel method based on SPECT/CT was developed to quantitative characterized the bone viability of femoral head and subchondral bone prior to surgery and at 3 months after VFG. All patients were followed for an average duration of 3.8 years (ranging 2.6-5.5 years). RESULTS The bone viability of the femoral head (Vfh) and subchondral bone (Vsb) of patients' hips at ARCO stage III was 58.9±7.6 and 48.9±6.1, respectively, which were significantly lower than the preoperative Vfh (78.1±5.2) and Vsb (69.8±4.3) of hips at stage II (P<0.05). The Vfh of hips at stage II improved to 104.0±9.7 at 3 months post-intervention, and there was no significant difference compared with the Vfh (97.3±7.4) of hips at stage III (P=0.15). The Vsb of hips at stage III improved to 80.4±7.3 at 3 months after VFG; however, this value was significantly lower than that of hips at stage II (92.7±5.5) (P<0.05). CONCLUSIONS The Vfh and Vsb of our patients were associated with their ARCO stages, and could be improved after vascularized fibular grafting procedure as measured by SPECT/CT.