Abstract
Proximal displacement of the femoral head can been seen sometimes after Chiari pelvic osteotomy. In order to clarify the causes of the displacement, a quantification analysis was performed to evaluate the preoperative and postoperative factors of this osteotomy. Statistical analysis showed that 54% of the causes could be explained as being due to 1) the angle of the osteotomy, 2) obesity, 3) the difference of the acetabular trochanteric distance, 4) the preoperative C.E. angle, 5) changes of the lever arm, and 6) the stage of coxarthrosis.
Paying attention to the following things is considered important in the operation to get good results: 1) making the angle of the osteotomy f r om 11° to 20°, and 2) keeping the difference of the acetabular trochanteric distance within 20mm, 3) the changes of the lever arm within 15%, and 4) the approximate acetabular index within 30%.
