The results of cementless stems in total hip arthroplasty (THA) done because of congenital dislocation with step-cut osteotomy is not well known, particularly the influence of the design and the role of extent of porous coating. Therefore, we performed a retrospective study to evaluate the mid- to long-term results THA performed with a single type acetabular component and different geometry and fixation type stems with ceramic bearings in the setting of step-cut subtrochanteric osteotomy in high hip dislocated (HHD) patients. We asked if the stem type affect the outcomes in terms of (1) intra- and postoperative complication rates, (2) radiographic outcomes, (3) prosthesis survival in step-cut subtrochanteric shortening osteotomy.

The type of the stem, whether cylindrical or tapered does not affect the outcome if the femoral canal fit and fill is obtained and the step-cut femoral shortening osteotomy is primarily fixed.

Forty-five hips in 35 patients with a mean follow-up of 10 years (range, 7–14 years) were evaluated. The single type cementless cup was placed at the level of the true acetabulum, a step-cut shortening femoral osteotomy was performed and reconstruction was performed with two different types of tapered stem in twenty-two hips (Synergy™ and Image™ proximally coated, Smith and Nephew, Menphis, TN, USA) and one type of cylindrical stem (Echelon™ with 2/3 coated, Smith and Nephew, Menphis, TN, USA) in twenty-three hips. Harris hip scores (HHS) and a University of California Los Angeles (UCLA) activity scores were calculated for all patients and successive X-rays were evaluated regarding component loosening and osteolysis, along with complications related to bearing, step-cut osteotomy and stem types.

Forty-one hips (91%) had good and excellent clinical outcome according to HHS. The mean UCLA activity scores improved from 3.2±0.6 points (range, 2–4) preoperatively to 6.3 points±0.5 (range, 5–7) at the latest follow-up. The mean femoral shortening was 36±10mm (range, 20–65mm). Four (9%) dislocations were observed. There were five (11%) intraoperative femoral fractures and three (7%) cases of nonunion, which were observed in tapered stems. Cylindrical stems had superior neutral alignment primarily. With any stem revision as the end point, cylindrical stems had a higher survival rate (100%) than all tapered stems (82%; 95% confident interval [CI] 77%–97%) at ten years. With any revision as the end point, the 10-year survival rate for acetabular component (Reflection-Ceramic Interfit) and for femoral components were 98% (95% CI, 85%–99%) and 91% (95% CI, 78%–97%), respectively.

There were more implant related complications in HHD patients undergoing THA when tapered stems with 1/3 proximal coating were used to reconstruct a step-cut osteotomized femur, compared to cylindrical stems 2/3 coated.

IV, retrospective study.