Long-term results of the threaded Mecron cup in primary total hip arthroplasty

Abstract

In the 1970s, high failure rates of cemented acetabular components, especially in young patients, in the middle-and long-term prompted a search for alternatives. The Mecring was one of the most popular first generation uncemented, threaded cups widely used in the 1980s for arthroplasty of the hip. First generation threaded cups commonly had smooth surface treatment and showed unacceptably high failure rates in the midterm. In a consecutive series of 209 patients, 221 threaded uncemented acetabular cups with smooth surface treatment (Mecring) had been implanted in combination with one type of uncemented stem. Patients were followed up clinically and radiographically. The mean time of follow-up was 17 (range 15-20) years. In 91 (41%) hips the acetabular component had been revised or was awaiting revision: two hips for infection and 84 (38%) for aseptic loosening. Five hips were awaiting revision. The survival rate for all revisions including hips awaiting revision was 49% (95% CI: 41-57%) at 17 years. These results support the view that smooth, threaded acetabular components do not provide satisfactory long-term fixation and should be abandoned. Patients with these components must be closely monitored as the failure rate remains high in the long-term.

Long-term results of cementless femoral reconstruction following intertrochanteric osteotomy

“…The unacceptably high failure rates of the threaded cups implanted in this cohort have been reported previously [29,30] and can be explained by the smooth surface treatment of these components which impedes osteointegration. These implants are no longer in clinical use.…”

Acetabular Components in Total Hip Arthroplasty: Is There Evidence That Cementless Fixation Is Better?

“…Although initial acetabular components were cemented, cementless acetabular components have gained popularity over the years and have become the primary components of choice in North America. This is despite the availability of ample literature supporting the use of cemented acetabular components [2][3][4][5][6] and suggesting a less optimal survivorship for cementless components [7][8][9][10][11][12][13][14] . However, there is a lack of long-term studies on the improved cementless implants that may have the potential for better survivorship and durability.…”

“…It is certain that earlier designs of cementless acetabular components were responsible for substantial underperformance of these components. For example, threaded acetabular components with a smooth surface treatment had the worst survival rate in the long-term studies 8,14 . However, inclusion of these studies in the present meta-analysis will not impact the results and comparisons substantially because many studies involving early cemented acetabular components with crude cementing techniques and poor performance were also included 33,34 .…”

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

“…In addition, when compared with other migration analysis studies using EBRA-FCA [9,19,38], our dropout rate was lower. We also recognize a possible bias because the acetabular components used in this cohort showed a high rate of aseptic loosening [7,8], as patients with cup loosening might reduce their activity which could influence wear and aseptic loosening of the stem; surgery for cup loosening also might have an influence on stem revision rate. Further, the migration threshold of 2.7 mm in this study using a single stem design might not apply to other stem designs, since such thresholds are almost certainly implant-specific.…”

“…However, prediction of longterm implant performance is difficult and definitive results regarding aseptic loosening are available only after lengthy followup [24,32,33]. Widespread use of poor-performing implants might occur before these results are available [7,8]. Therefore, reliable methods are needed to predict aseptic loosening and allow early evaluation of long-term implant performance during the first years after implantation.…”