The influence of the insufficient developmental shape of acetabulum on the collapse occurrence of osteonecrosis of the femoral head (ONFH) was reported rarely after intertrochanteric curved varus osteotomy (CVO). The purpose of the study was to quantitatively evaluate the influence of different weight-bearing portions on collapse risk of femoral head necrosis after CVO with a finite element method.
Insufficient weight-bearing portion and normal weight-bearing portion hip joint finite element models of CVO (15°, 20°, 25° and 30°) for osteonecrosis of the femoral head with a lesion of 60°, dividing into three types (A, B and C1) were simulated. The Mises strain and collapse index were analyzed in terms of the lesion.
The maximum and mean Mises strain were higher in insufficient weight-bearing portion models with a positive quantitative increment of strain, especially for type C1 and B in no osteotomy situation. However, the collapse index was more than 1.0 in type C1, even after some degree of this CVO, and in type B of insufficient weight-bearing situation.
Progressive collapse risk was increased in the insufficient weight-bearing portion situation. Thus, the decision-making of CVO for the treatment of osteonecrosis of the femoral head should be different with insufficient weight-bearing portion of the acetabulum. We recommended that the unfavorable biomechanical shape of acetabulum should be treated before this CVO was performed when the necrotic type was more than B.