Clinical and radiological outcomes of the SL-Plus stem with a minimum 10-year follow-up: A retrospective study.

Abstract

Purpose: The SL-Plus cementless stem was introduced in 1993 as an evolution of the Alloclassic® stem with some modifications. The aim of this study was to analyse if these modifications have any influence in clinical and radiological outcomes at minimum 10-year follow-up.

Methods: Sixty-eight consecutive implants (64 patients) were retrospective evaluated. The mean duration of clinical and radiographic follow-up was 12.2 years. There were 41 female and 23 male patients with a median age of 73.5 years. All complications and reinterventions were collected. Functional outcomes were assessed using the modified Harris Hip Score (mHHS). Radiographs were evaluated immediately after the operation, after a minimum 2-year follow-up and by the end of follow-up (time A, B and C, respectively).

Results: Two stems were revised, one due to periprosthetic fracture and one due to aseptic loosening with a cumulative probability of not having a stem revision for any reason of 97.2% at 12.2 years. Mean mHHS was 76.7 points at the latest follow-up. Significant differences were found in distal migration (time A: 5.9mm±6.7; B: 6.9mm±7.1 and C: 8.2mm±6.3; P=.000) and varus angulation (time A: 0.0°±2: B: 0.0°±2 and C: 1.0°±3; P<.001), although these stems showed radiographic signs of osseointegration. Thirty-three hips (48.5%) showed any radiolucent line around the stem, most of them located the proximal femur (Gruen 1 and 7). Multivariate regression analysis showed lower mHHS scores in older patients (P=.004) and female (P=.00).

Conclusions: The modifications of the SL-Plus stem influence the long-term outcome of the implant regarding radiological results, particularly in progressive varus angulation and distal migration. However, our study has not been able to demonstrate any clinical repercussions: functional scores and survival free of all cause revision were favorable and comparable to previous reports.