A Minimally Invasive Technique Using a Modified Stoppa Approach for Periacetabular Osteotomy: A Preliminary Cadaveric Study

BACKGROUND: Developmental hip dysplasia is diagnosed when the femoral head is not sufficiently covered by the acetabulum. Anterior and lateral cover deficiency is seen, as a result a dysplastic hip joint. Various incision modifications have been developed because of the muscle dissection and wide wound scar in Smith-Peterson incision, which was originally used in Bernese osteotomy. This study evaluates applicability of the modified Stoppa approach in the performance of Bernese periacetabular osteotomy (PAO). MATERIALS AND METHODS: Ten hemipelvises of five donor cadavers were used. The transverse Stoppa incision was made 2 cm over the symphysis pubis for quadrilateral surface exposure and pubic and ischial bone osteotomies. The second skin incision, a few centimeters lateral to the original incision, was made along the tensor fascia lata. Iliac bone osteotomy was performed starting just above the rectus femoris insertion. The displacement of the osteotomy was measured clinically and radiographically. RESULTS: The mean anterior coverage calculated with center-edge angle was improved from 22.8° ±2.8 (range 20° min–28° max) preoperatively to 44.1° ± 3.7 (range 36° min–48° max). The displacement of the osteotomy at the iliopectineal line calculated on the iliac inlet view radiographs was 22.1 ± 3.4 mm (range 15 mm min–26 mm max). The clinical amount of the anterior displacement on the cadavers was 17.8 ± 3.35 mm (range 11 mm–21 mm) and lateral displacement was 20.3 ± 3.23 mm (range 15 mm–24 mm). The amount of the posterior intact bone enlargement at the quadrilateral surface was 5.3 ± 0.48 mm. CONCLUSION: This less traumatic two-incision exposure is an adequate technique for Bernese PAO, allowing the bone to be cut under direct visual observation and reducing the need to use fluoroscopy.