Long-term results of the threaded Weill cup in primary total hip arthroplasty: a 15-20-year follow-up study

Early Migration Predicts Aseptic Loosening of Cementless Femoral Stems: A Long-term Study

BACKGROUND

Excessive early migration of cemented stems and cups after THA has been associated with poor long-term survival and allows predictable evaluation of implant performance. However, there are few data regarding the relationship between early migration and aseptic loosening of cementless femoral components, and whether early migration might predict late failure has not been evaluated, to our knowledge. Einzel-Bild-Röntgen-Analyse-femoral component analysis (EBRA-FCA) is a validated technique to accurately measure axial femoral stem migration without the need for tantalum markers, can be performed retrospectively, and may be a suitable tool to identify poor performing implants before their widespread use.

QUESTIONS/PURPOSES

We asked: (1) Is axial migration within the first 24 months as assessed by EBRA-FCA greater among cementless stems that develop aseptic loosening than those that remain well fixed through the second decade; (2) what is the diagnostic performance of implant migration at 24 months postoperatively to predict later aseptic loosening of these components; and (3) how does long-term stem survivorship compare between groups with high and low early migration?

METHODS

We evaluated early axial stem migration in 158 cementless THAs using EBRA-FCA. The EBRA-FCA measurements were performed during the first week postoperatively (baseline measurement) and at regular followups of 3, 6, and 12 months postoperatively and annually thereafter. The mean duration of followup was 21 years (range, 18-24 years). The stems studied represented 45% (158 of 354) of the cementless THAs performed during that time, and cementless THAs represented 34% (354 of 1038) of the THA practice during that period. No patient enrolled in this study was lost to followup. Multivariate survivorship analysis using Cox's regression model was performed with an endpoint of aseptic loosening of the femoral component. Loosening was defined according to the criteria described by Engh et al. and assessed by two independent observers. Patients with a diagnosis of prosthetic joint infection were excluded. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance of axial stem migration 1, 2, 3, and 4 years postoperatively as a predictor of aseptic loosening. Survivorship of hips with high (≥ 2.7 mm) and low (< 2.7 mm) migration was compared using a competing-events analysis.

RESULTS

Femoral components that had aseptic loosening develop showed greater mean distal migration at 24 months postoperatively than did components that remained well fixed throughout the surveillance period (4.2 mm ± 3.1 mm vs 0.8 mm ± 0.9 mm; mean difference, 3.4 mm, 95% CI, 2.5-4.4; p ≤ 0.001). Distal migration at 24 months postoperatively was a strong risk factor for aseptic loosening (hazard ratio, 1.98; 95% CI, 1.51-2.57; p < 0.001). The associated overall diagnostic performance of 2-year distal migration for predicting aseptic loosening was good (area under the ROC curve, 0.86; 95% CI, 0.72-1.00; p < 0.001). Sensitivity of early migration measurement was high for the prediction of aseptic loosening during the first decade after surgery but decreased markedly thereafter. Stems with large amounts of early migration (≥ 2.7 mm) had lower 18-year survivorship than did stems with little early migration (29% [95% CI, 0%-62%] versus 95% [95% CI, 90%-100%] p < 0.001).

CONCLUSIONS

Early migration, as measured by EBRA-FCA at 2 years postoperatively, has good diagnostic capabilities for detection of uncemented femoral components at risk for aseptic loosening during the first and early second decades after surgery. However, there was no relationship between early migration patterns and aseptic loosening during the late second and third decades. EBRA-FCA can be used as a research tool to evaluate new cementless stems or in clinical practice to evaluate migration patterns in patients with painful femoral components.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Long-term results of cementless femoral reconstruction following intertrochanteric osteotomy

PURPOSE

The objective of this retrospective cohort study was to assess the long-term outcome of cementless femoral reconstruction in patients with previous intertrochanteric osteotomy (ITO).

METHODS

We evaluated the clinical and radiographic results of a consecutive series of 45 patients (48 hips, mean age 50 years) who had undergone conversion hip replacement following ITO with a cementless, grit-blasted, double-tapered femoral component. Clinical outcome was determined using the Harris hip score. Stem survival for different end points was assessed using Kaplan-Meier survivorship analysis.

RESULTS

At a mean follow-up of 20 (range, 16-24) years, 11 patients (12 hips) had died, and no patient was lost to follow-up. Six patients (six hips) underwent femoral revision, two for infection, three for aseptic loosening and one for periprosthetic fracture. Mean Harris hip score at final follow-up was 78 points (range, 23-100 points). Stem survival for all revisions was 89% (95%CI, 75-95) at 20 years, and survival for aseptic loosening was 93% (95%CI, 80-98).

CONCLUSIONS

The long-term results with this type of cementless femoral component in patients with previous intertrochanteric osteotomy are encouraging and compare well to those achieved in patients with normal femoral anatomy.

17-year follow-up of the rough-blasted threaded Weill cup in uncemented total hip arthroplasty

INTRODUCTION

For uncemented hip arthroplasty, various cup designs are available. The threaded Weill acetabular component (Weill cup; Zimmer, Winterthur, Switzerland) has been used for more than 20 years, with poor results of the smooth threaded design. Our study was intended to assess the 17-year outcome of the rough-blasted option of the threaded Weill cup.

MATERIALS AND METHODS

Between 1987 and 1988, a series of 86 rough-blasted threaded Weill cups were implanted in combination with the CLS Spotorno stem (Zimmer Ltd, Germany) The patients' mean age at the time of surgery was 50 years (range 19-67 years). 67 out of 86 hips (78%) were available for a follow-up at a mean of 17 years (range 16-18 years). Radiographs were available from 55 out of 63 unrevised hips (87%) and analyzed for radiolucency and PE wear.

RESULTS

Two out of 86 cups (3%) were revised due to aseptic loosening and another two cups (3%) were awaiting revision for the same reason. Ten patients (10 cups, 12%) were lost to follow-up, and nine patients with nine cups (11%) had deceased without radiographic signs of cup failure. Cup survival with "revision or awaiting revision" as endpoint was 86% (95% CI 75-92%). No deep infections occurred, and no polyethylene insert was exchanged. The Harris hip score was excellent in 37 out of 67 clinically examined hips (55%), good in 18 hips (26%), satisfactory in 5 hips (8%) and moderate or poor in 5 hips (8%) and 2 hips (3%), respectively.

CONCLUSION

The rough-blasted threaded Weill cup provides a good long-term performance in cementless total hip arthroplasty. The results compare favourably to the smooth threaded cup design.

The Bicontact cementless primary total hip arthroplasty: long-term results

We report on a prospective series of 201 primary uncemented total hip arthroplasties with a Bicontact prosthesis at a mean follow-up of 12.9 years. The mean Harris hip score improved from 41 before surgery to 89 at final follow-up. Two femoral stems, one each for infection and fracture, and 12 cups were revised. The mean number of years to revision post-primary surgery was 8.7 years (six months to 16 years). The cumulative survival of the prosthesis was 95.42% for any cause at ten years and 93.57% at 12 years. Survivorship for aseptic loosening of the femoral stem was 100%. In our series, the Bicontact uncemented total hip arthroplasty stem without hydroxyapatite coating showed excellent survival and the cup survival was comparable to other leading series.