Between April 2013 and October 2019, 13 patients (13 hips) were treated with THA in combination with modified trochanteric osteotomy. All operations were performed by one surgeon (Yoon TR). There were three men and ten women. The average age of patients at the time of surgery was 50 ± 9.4 years (range, 31-68 years). Five patients received the procedure on the right side and eight patients had the procedure on the left side. No patients were lost to follow-up, with a mean follow-up period of 5.2 ± 0.8 years (range, 4.9-6.1 years) (Table 1). All subjects had Crowe group IV DDH according to the classification of Crowe et al. This study was cleared through the ethics committee of our hospital. Informed consent was obtained from each patient. No patient underwent any hip surgery before the procedure.
Metal cup (Lima-Lto, Udine, Italy) with ceramic on ceramic (Biolox, Osteo AG, Selzach, Switzerland) bearing (COC) was used for all prosthetic acetabulum. Wagner Conical stem (Zimmer, Winterthur, Switzerland) was used in all cases. Cable and screw (13 hips) with a grip plate system (13 hips) (Dall Miles®, Stryker Orthopedics Inc., Mahwah, NJ, USA) were used for fixation of the greater trochanter to prevent intraoperative proximal femoral site fracture.
All patients underwent the surgery in lateral decubitus position with a posterolateral approach. A provisional osteotomy was usually performed at the inferior half of the lesser trochanter. After adequate exposure, the true acetabulum was widened and deepened by the reamer. To avoid excessive reaming or acetabular wall fracture, the reaming was performed mainly in superior and posterior directions where the bone stock was usually thick enough. After preparing the true acetabulum, the final metal cup (Lima-L to, Udine, Italy) with ceramic on ceramic (Biolox, Osteo AG, Selzach, Switzerland) bearing was inserted. If the cup coverage was still not satisfied, bulk bone autografts with resected femoral head were utilized to provide adequate coverage of the acetabular cup.
In all hips, Wagner cone prosthesis (Zimmer, Winterthur, Switzerland) was used. If the proximal part of the femur considered to be weak after femoral reaming, prophylactic cerclage wiring was used to avoid proximal fragment fracture during the reaming of the medullary canal or insertion of the stem into the femur. The stem size was chosen during preoperative planning and intraoperatively considering soft tissue tension. Stems were inserted at 15 degrees of anteversion. After the final reduction, the greater trochanter was reattached to the proximal femur using +/- cortical screw, cables, and grip plate with the hip abducted position (Fig. 1).
Antibiotic prophylaxis was done before surgery and at one or two days after surgery. Exercise for range of motion was encouraged after two to three days of bed rest; non-weight bearing, postoperative the patient followed crutch ambulation. Complete weight-bearing was permitted only after obtaining radiographic confirmation of bone union. Active exercises were then strongly encouraged to stretch and strengthen abductor muscles.
Preoperative data (such as hemoglobin level), blood loss, transfusion requirement, surgical time, post-operative complication, and radiological and clinical outcomes were assessed. Total blood loss was defined as intra-operative blood loss plus the volume of blood that was collected in the drain before removal. The drain was removed after 24 hours with drainage of less than 100 ml. Hemoglobin level was measured the day before surgery. Total number of transfusions including PRCs (packed red blood cells), fresh frozen plasma, and platelet concentrates used intra- and postoperatively was recorded. Surgical time was described from the time of incision to complete the wound completely. Details are summarized in Table 2
Medical history affecting the operation (as heart disease and deep vein thrombosis), physical examination (as Trendelenburg sign, limping gait), and radiographic evaluations (lumbosacral spine, lower limb, and pelvis) were obtained or performed for all patients preoperatively. True acetabulum parameters were obtained by 3D-CT. Templated measurements from anteroposterior and oblique hip radiographs were performed preoperatively to determine the location of the true acetabulum, the level of the femoral neck osteotomy, stem size, and cup size.
After the surgery, patients were followed up monthly until union at the osteotomy site and at 6 months, 1 year, and annually thereafter. At the postoperative visit, patients were evaluated with Harris Hip Score (HHS). Radiological evaluations were also performed. HHS was rated as excellent when it was greater than 90 points. It was considered as good when it was between 80 and 89 points. Excellent and good scores were considered to represent successful outcomes. When HHS was between 70 and 79 points, it was classified as fair. HHS of less than 70 was regarded as poor. Radiological evaluations were performed for reviewing acetabular component anteversion, acetabular lateral opening angle, radiological leg length measurement, the stability of the femoral stem and acetabular component, and the time of the osteotomy site union.
Leg length discrepancy was measured preoperatively and postoperatively with the method described by Sabharwal et al. . To measure acetabular cup anteversion, we used the method described by Sah and Estok . Stem subsidence was measured with the method of Callaghan et al. . To measure acetabular and stem location of the extent of radiolucency, we used the method of De Lee and Charnley  and Gruen et al. . To evaluate stem and cup loosening, we used methods of Harris et al.  and Hodgkinson et al. . Leg lengthening was measured with the method described by Park et al. .
All statistical analyses were performed using the SPSS software package version 19.0 (SPSS Inc. Chicago, IL, USA). Two-sided, paired Student’s t-test was used to analyze preoperative and postoperative continuous variables. Statistical signiﬁcance was considered when p value was less than 0.05.