An oblique osteotomy is better for subtrochanteric shortening in total hip arthroplasty for high hip dislocation: a mechanical comparison of four techniques

Background: Subtrochanteric femoral shortening is used during total hip arthroplasty for high hip dislocation in developmental dysplasia of hip patients. Methods: We mechanically tested the stability of various commonly used subtrochanteric osteotomy techniques. As the equivalent of a femoral stem placed in a shortened femur without any stable fixation at the osteotomy line, 2 polyvinylchloride pipes were loosely intertwined. 4 different osteotomies (Z-subtrochanteric osteotomy, oblique-45 degrees osteotomy, double Chevron-90 degrees and 120 degrees subtrochanteric osteotomy) were simulated. Torsional and axial loads were applied, and torsional stiffness was calculated for each test model. Results: Z, double Chevron-90 degrees and 120 degrees subtrochanteric osteotomy models demonstrated lower mean torsional stiffness than oblique-45 degrees osteotomy. With the highest torsional stiffness oblique-45 degrees provides the best stability for treatment of high dislocation hips when a subtrochanteric osteotomy is added. Conclusions: This matches our previous clinical experience. Oblique osteotomy may also provide higher contact surfaces in the osteotomy lines to promote bone healing.

Automated summary

The stability of different subtrochanteric osteotomy techniques was mechanically tested, and the oblique-45 degrees osteotomy showed the best stability when combined with subtrochanteric osteotomy. This technique may also promote bone healing by providing larger contact surfaces in the osteotomy lines.