The purpose of this study was to ascertain the radiographic results of the modified extended trochanteric sliding osteotomy (ETSO), performed by the senior author. The main feature of the ETSO is preservation of the posterior 1cm of greater trochanter and its attached external rotators. Results with this particular osteotomy for revision hip arthroplasty have not been previously reported.

We reviewed forty-eight ETSOs in forty-six patients that underwent revision hip arthroplasty from March 2000 to March 2006. Nineteen osteotomies were for femoral revision alone, and twenty-nine osteotomies were performed for femoral and acetabular revision. All but six (12.5%) had cortical strut augmentation of the osteotomy. The length of the osteotomy, the length of distal fit, the number of wires used were recorded and their relation to union of the osteotomy and femoral stem loosening were investigated.

The rate of ETSO union in this study was 91.3%. Four osteotomies were not united and this was associated with femoral stem subsidence and loosening requiring femoral stem revision in three cases. The rate of femoral stem loosening requiring revision was 8.3%. The length of the osteotomy did not correlate with femoral stem loosening, but a distal fit of less than 9cm was highly significant(p=0.001) with regards to loosening. The use of cortical struts was not protective against osteotomy non-union or femoral stem loosening. Osteotomy union was shown to be dependant on a well fixed (p< 0.0001) and stable stem (p< 0.0001). Three patients dislocated postoperatively (6.5%), and only one of these required revision surgery.

The modified extended trochanteric osteotomy has a low rate of dislocation and a reliable rate of union. We have shown that a well fixed and stable stem is critical to successfully obtaining union of the osteotomy.