Abstract
Postoperative peritrochanteric pain, which can be caused by non-union of the greater trochanter in those who have undergone total hip arthroplasty (THA) with trochanteric osteotomy, affects patient satisfaction. We reviewed 89 consecutive cases of primary THA performed with a mini-trochanteric direct lateral approach (Wafer approach), during which the anteroinferior trochanteric fragment (2 cm × 1 cm) attached to the anterior one-third or one-fourth of the gluteus medius muscle insertion and the entire insertion of the gluteus minimus muscle were osteotomized and detached using a curved chisel for exposure, while the origin of the vastus lateralis muscle remained intact. After completion of implantation, the detached fragment was fixed in the original position using 2 parallel braided sutures. If returning the trochanteric fragment to its original position was difficult, the tightened posterior tendinous portion of the gluteus minimus muscle was released to reduce the fragment easily and was then fixed. The surgeries, which included 19 cemented, 7 cementless, and 63 hybrid THAs, were performed between January 2012 and August 2013, and the patients [13 men, 76 women; average age, 65.6 years (38–86 years)] were followed for 6 months. The original diagnosis included primary osteoarthritis in 7 cases, osteoarthritis secondary to dysplasia in 75 cases, and avascular necrosis of the femoral head in 7 cases. X-ray examination including anteroposterior (AP) and lateral hip views was performed at 1, 3, and 6 months postoperatively, and a displacement of > 5 mm of the osteotomized fragment in either the AP or lateral view was considered fragment migration. The Japanese Orthopaedic Association (JOA) pain score was also recorded at 3 and 6 months postoperatively. We examined the possible factors affecting trochanteric migration and JOA pain score, including age, sex, THA type, leg lengthening, Crowe classification, and suture type. We also examined the correlation between trochanteric migration and JOA pain score. There were no peri- or post-operative complications including infection, deep venous thrombosis, dislocation, or periprosthetic fracture. No revision or radiographic loosening occurred in the follow-up period. Average leg lengthening was 9.8 mm (−4–21 mm), measured on the AP X-ray of the hip as the vertical interval between the pre- and postoperative positions of the lesser trochanter. There were 35 cases (39.3%) of trochanteric migration at postoperative 3 months. The Chi-square test and logistic regression analysis indicated that age, sex, Crowe classification, leg lengthening, and suture type did not affect trochanteric migration or JOA pain score. On the other hand, THA type did not affect trochanteric migration but did affect JOA pain score at postoperative 3 months. Patients who underwent cementless THA had worse JOA pain scores than the other patients. There was no correlation between trochanteric migration and JOA pain scores. The results indicated that trochanteric fragment migration often occurred in this series using the Wafer approach. Although the pain score is affected by many factors including thigh pain, hip abductor weakness, and wound irritation in the short term, it did not correlate with the trochanteric nonunion rate of this approach.
