gms | German Medical Science

Objectives: The combination of hemodynamical and bone trabecular parameters change may contribute to the development of osteonecrosis of the femoral head (ONFH), which leads to inadequate bone repair that advances to subchondral fracture. From January 2008 to December 2012, images and pathological analysis of 30 femoral head osteonecrotic cases were carried to explore characteristics of lesions at different phases and stages.

Methods: From January 2008 to December 2012, thirty patients (30 hips) osteonecrosis of the femoral head cases were enrolled. Inclusion criteria include, 1. The diagnosis of osteonecrosis of the femoral head was clear. 2. No history of infection was diagnosed in the affected hip, no history of hip surgery, no congenital hip diseases; 3.The studied necrotic femoral heads were all taken after hip arthroplasty. There were 14 females and 16 males,aged from 47 to 69 years(mean, 56.1 years). Affected hips were classified by ARCO staging system, including ARCO Ic 2 hips,ARCO IIc 5 hips, ARCO III b 5 hips, ARCO III c 6 hips and ARCO IV 12 hips. All patients underwent total hip arthroplasty due to severe joint pain. Preoperative data of X-ray, CT, MRI and selective angiography (DSA) were taken. Micro-CT and pathological examination were performed after the femoral heads were take after hip replacement.

Results and Conclusion: Angiographic findings of the blood supply to the femoral head revealed that the mean time of perfusion in ARCO IV was significantly different from that in ARCO I, II and III. The average perfusion time of ARCO I,II,III and IV was11.6,11.4, 12.4s and 19.1s. Micro-CT scan and histological examination of femoral head necrosis specimens of different stages showed that the bone repair was consistent with the changes of microstructure of trabecular, osteogenesis lagged behind osteoclasia of the trabecular, and cystic region was filled with fiber connective tissue.After rapid osteoclasia, osteogenesis process lost its original framework however enough artery blood supply led tomultiple osteogenic foci intra-bone marrow cavity and coexistence of sclerotic bone,necrotic bone and cystic lesion. Bone histomorphometrical and pathological study both revealed that during the process of femoral head collapse, the trabecular parameters changed and hemodynamic changed accordingly.

Our hemodynamical and pathological studies found that early stage of ONFH characteristic presented as venous stasis and advanced stages presented insufficient artery blood supply to the femoral head. In this sense, the progress of the ONFH could be divided into venous stasis phase, arterial ischemia phase and arterial occlusion phase.