The utility of clinical features for distinguishing subchondral insufficiency fracture from osteonecrosis of the femoral head

Purpose: Subchondral insufficiency fractures of the femoral head (SIF) need to be differentiated from osteonecrosis of the femoral head (ON), since these two conditions have several overlapping characteristics especially in their radiological findings. The purpose of this study was to determine the useful clinical features for differentiating SIF from ON. Methods: This study reviewed 44 consecutive patients, aged 60 years or older with a radiological evidence of subchondral collapse of the femoral head. According to the histopathological diagnosis, 22 patients were grouped as SIF and 22 patients as ON. A 2 × 2 contingency table analysis was used to obtain the odd ratios (ORs) for SIF compared to ON. Results: The age, proportion of females, the rate of a history of either corticosteroid intake or alcohol abuse, and the presence of vertebral compression fracture in subchondral insufficiency fracture were significantly higher than those with osteonecrosis (p = 0.0001, 0.0212, 0.0001, and 0.0040, respectively). ORs for SIF were 12.01 [95 % confidence intervals (CI) 1.35-106.80] and 7.29 (95 % CI 1.91-27.86), if the patient were female and 70 years of age or older, respectively. In addition, OR for SIF was extremely high (OR 56.01, 95 % CI 6.12-512.87) compared to ON, if the patients have a history of either corticosteroid intake or alcohol abuse. Conclusion: The results of this study indicate that osteoporotic elderly women without any history of corticosteroid intake or alcohol abuse need to first be considered to have subchondral insufficiency fracture when radiographs show a collapse of the femoral head.