Because there is no consensus regarding the factors predicting femoral head collapse in asymptomatic osteonecrosis of the hip, we studied the risk factors for collapse. Between 1990 and 2000, we used MRI to confirm asymptomatic osteonecrosis of the femoral head in 81 patients (81 hips) whose other hip had nontraumatic symptomatic osteonecrosis and we monitored them prospectively. The minimum followup was 5 years (mean, 8.3 years; range, 5-16 years). At the latest followup, 31 hips (38%) were symptomatic and 26 hips (32%) had collapsed. The mean interval between diagnosis and collapse was 4.1 years. We observed no correlation between femoral head collapse and patients' age, gender, weight, presumed cause of osteonecrosis, or length of followup. With combined factors, only extent of large necrotic lesion (hazard ratio, 4.06; 95% confidence interval, 1.29-12.77) and location of Type C2 necrotic lesion (hazard ratio, 6.35; 95% confidence interval, 1.18-34.11) predicted collapse.
The multimodal pain control protocol was found to offer more effective postoperative pain control with fewer adverse effects than intravenous patient-controlled analgesia. However, achieving adequate pain control within the first 48 h of surgery remains challenging, and thus, the developments of more effective and safer multimodal pain control protocols are required.
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