LIU Bao-yi, ZHAO De-wei, YU Xiao-bing, YANG Lei, GUO Lin and WANG Ben-jie

Background Osteonecrosis of the femoral head (ONFH) is the result of dysfunctional blood supply, but associations between specific damaged arteries, imaging changes and clinical sign require more understanding. We investigated characteristics of ONFH that pertain to blood supply, imaging appearance, and clinical feature to judge the prognosis of ONFH.
Methods Clinical data were collected for 92 patients (118 hips) with ONFH, including gender, age, duration of pain (from initial clinical presentation to arthroplasty), cause, stage, and classification. Magmatic resonance imaging and X-rays were obtained of all patients to diagnose ONFH. The sizes of lesions were classified by necrotic index. The location of necrosis was classified as Type A, B, or C using the grading system by magmatic resonance imaging and X-rays. All hips were imaged with digital subtraction angiography to visualize their blood-supply characteristics. Hips were divided into groups based on the source artery for femoral head damage: superior retinacular artery (S), inferior retinacular artery (I), and combined superior and inferior retinacular arteries (S+I). Via digital subtraction angiography, imaging appearances and clinical data in three groups were compared.
Results ONFH was caused by damage in either the superior or inferior retinacular artery, or both, in all of 118 hips. The group with only inferior retinacular artery damage reported longer hip pain duration than the other groups. The probability of the lesion extending laterally to the acetabular edge in group S was much more than it in group I. Necrosis indices of the patients in S and S+I were higher than those in group I.
Conclusions ONFH associated with interruption of the superior and inferior retinacular arteries in this study. When the former alone was damaged, the necrosis of the volume was larger, the risk of femoral head collapse was higher and the time from initial clinical presentation to arthroplasty was shorter.