BackgroundTotal hip athroplasty (THA) in Crowe IV developmental dysplasia of the hip (DDH) presents many challenges for surgeons with regard to acetabular and femoral deformities. The purposes of this study are to (1) report the mid-term results of THA with subtrochanteric transverse osteotomy using S-ROM prosthesis and ceramic-on-ceramic (COC) surface for Crowe type IV DDH; and (2) compare the wear performance between COC and metal-on-polyethylene (MOP) bearing couple.MethodsEighty Crowe IV DDH patients (103 hips) treated with cementless THA were retrospectively reviewed. The S-ROM prosthesis was used in all the hips and subtrochanteric osteotomy was performed in 74 hips. COC and MOP bearing surfaces were compared through the evaluation.ResultsAt mean follow-up of 65.6 months, the mean Harris hip score improved from 54.2 to 87.7 points; however, Trendelenberg sign positive was confirmed in 20.4% of the hips. Postoperative dislocation occurred in 6 cases and overall 4 hips were revised. With any component revision as endpoint, Kaplan-Meier survival curve showed that 8-year cumulative survival rate in the COC group was 97.2% and 9-year survival rate in the MOP group was 85.9%. The mean linear wear rate for COC and MOP surface was 0.006 and 0.175 mm/y, respectively.ConclusionsSubtrochanteric osteotomy combined with the modular S-ROM prosthesis and COC surface in Crowe IV DDH has achieved satisfactory mid-term results. However, postoperative dislocation and limp remain major complications. Linear wear rate for MOP surface is high and the long-term prosthesis survival is affected. Ceramic or highly cross-linked polyethylene should be preferred.

Objectives We aimed to show the utility of high hip center technique used in patients with Crowe II–III developmental dysplasia of the hip at the midterm follow‐up and evaluated the clinical and radiographic results between different heights of hip center. Methods From December 2003 to November 2013, we retrospectively evaluated 69 patients (85 hips) with Crowe II–III dysplasia who underwent a high hip center cementless total hip arthroplasty. The patients were divided into two groups according to the height of hip center, respectively group A (≥ 22 mm and < 28 mm) and group B (≥28 mm). The survivorship outcomes and radiographic and clinical results, including the vertical and horizontal distances of hip center, femoral offset, abductor lever arm, cup inclination, leg length discrepancy, Trendelenburg sign, and limp were evaluated. Results The mean follow‐up time was 8.9 ± 1.8 years. The mean location of the hip center from the inter‐teardrop was 25.1 ± 1.6 mm vertically and 30.0 ± 3.8 mm horizontally in group A, and 33.1 ± 4.8 mm vertically and 31.4 ± 6.1 mm horizontally in group B. Eleven hips of group B showed a lateralization over 10 mm, and the same was shown in one hip in group A (P = 0.012). There were no statistically significant differences between two groups in postoperative femoral offset, abductor lever arm, leg length discrepancy and cup inclination. At the final follow up, the mean WOMAC and Harris hip score were significantly improved in both groups. Of the 85 hips, four hips in group A and three hips in group B showed a positive Trendelenburg sign. Additionally, four patients in group A and two patients in group B presented with a limp. No significant differences were shown regarding the Harris hip score, WOMAC score, Trendelenburg sign, and limp between two groups. One hip of group A was revised by reason of dislocation at 8.3 years after surgery. One hip of group B was diagnosed with osteolysis and underwent a revision at 8.1 years after surgery. The Kaplan–Meier implants survivorship rates at the final follow‐up for all‐causes revisions in group A and group B were similar (96.7% [95% confidence interval, 90.5%–100%] and 96.2% [95% confidence interval, 89.0%–100%], respectively). Conclusions The high hip center technique is a valuable alternative to achieve excellent midterm results for Crowe II–III developmental dysplasia of the hip. Further, between the groups with differing degrees of HHC, there were no significant differences in outcomes or survivorship in our study.

ObjectiveTo explore the leg length balance in total hip arthroplasty (THA) with shortening subtrochanteric osteotomy (SSTO) or not for unilateral Crowe type IV developmental dysplasia of the hip (DDH) through the evaluation of postoperative full‐length anteroposterior radiographs.MethodsThe postoperative radiographs of 60 patients with unilateral Crowe type IV DDH from July 2012 to May 2019 were retrospectively reviewed. All patients underwent THA using the Pinnacle Acetabular Cup system, a ceramic liner and femoral head, and the S‐ROM stem with a proximal sleeve or cone. Patients with leg length discrepancy (LLD) < 10 mm were defined as the non‐LLD group. To identify differences associated with SSTO, the group was further divided into two groups based on whether the patient underwent SSTO. A total of 48 patients (26 for SSTO and 22 for non‐SSTO) were in the non‐LLD group. There were 3 male and 45 female patients. The mean age of the patients in the non‐LLD group was 39 years. These data, including leg length, femoral length, the height of center of rotation (COR) of the hip, the depth of the sleeve or cone in the femoral medullary canal and the height of the greater trochanter, were measured.ResultsIn the non‐LLD group, the femoral lengths in both SSTO and non‐SSTO groups were significantly shorter on the operated side compared with the contralateral side, and the mean discrepancy in the SSTO group was approximately equal to the mean length of the SSTO. The mean height of the COR of the hip on the operated sides in both SSTO and non‐SSTO groups was 13.2 mm, and the contralateral sides were 15.2 and 15.5 mm, respectively. The depth of the sleeve or cone in the femoral medullary canal between SSTO and non‐SSTO groups was 21.7 and 30.6 mm, respectively. The depth of the sleeve or cone in the SSTO group was negatively correlated with the length of SSTO. The heights of the greater trochanter in the operated and contralateral sides were 5.3 and 16.6 mm in the SSTO group, and 13.2 and 17.2 mm in the non‐SSTO group, respectively.ConclusionsShortening subtrochanteric osteotomy led to femoral shortening on the operated side for patients with unilateral Crowe type IV DDH. The position of the sleeve or cone should be close to the apex of the greater trochanter to compensate the length of the SSTO. The position of the sleeve or cone without SSTO should be adjusted to make sure that the height of the greater trochanter on the operated side is close to that on the contralateral side.

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