Modified osteotomy of posterolateral overhanging part of the trochanter via posterior approach for hip arthroplasty: an anatomical study.

BACKGROUD: The osteotomy of the posterolateral overhanging part (PLOP) of the greater trochanter via posterior approach has been used for the hip arthroplasty for decades with good results. However, the osteotomy method remains undefined and the precise adjacent structures around PLOP have not been reported. The purpose of this study was to present a modified PLOP osteotomy approach and perform a detailed study of the topographic and surgical anatomy of the PLOP. METHODS: The peri-PLOP soft tissue and the bony parameters were measured using 10 cadavers with 20 hips and 20 skeletal hip specimens, respectively. RESULTS: A 1.8-cm vertical osteotomy did not jeopardize the femoral neck, and a 1.8-cm wide bone block did not damage the insertions of the short external rotators. The average distances between the most distal branch of the superior gluteal nerve/artery and the 1.8-cm point of the greater trochanter were 5.70 ± 0.66 cm and 6.33 ± 0.56 cm, respectively. CONCLUSION: For osteotomy of the PLOP, we suggested that the width of the upper side from the lateral to medial greater trochanter should be 1.8 cm, depth of vertical osteotomy should be 1.8 cm, and length of the posterior edge should be 4 cm. Obturator externus tendon should be kept within the bone block of osteotomy. The proximal extension of the gluteus medius muscle split should be limited to 5.5 cm at the 1.8 cm-point of the greater trochanter. LEVEL OF EVIDENCE: Prospective comparative study Level II.