Research Article: The Exeter femoral stem continues to migrate during its first decade after implantation

Date Published: April 24, 2012

Publisher: Informa Healthcare

Author(s): Marc J Nieuwenhuijse, Edward R Valstar, Bart L Kaptein, Rob G H H Nelissen.

http://doi.org/10.3109/17453674.2012.672093

Abstract

Due to its collarless, double-tapered polished design, the Exeter femoral stem is known to migrate distally in the first 5 years after implantation. However, its long-term migration pattern has not been investigated.

39 consecutive patients (41 total hip arthroplasties) received a cemented Exeter stem and had prospective clinical and RSA follow-up. Patients were evaluated postoperatively at 6, 12, 26, and 52 weeks, and annually thereafter. Short-term results have been reported. In this study, the mean length of follow-up was 9.4 years (SD 3.2 years). No patients were lost to follow-up. 15 patients died during follow-up.

No stems were revised. In 4 stems, fractures of the cement mantle were noted within the first 3 postoperative years. In 3 stems, this resulted in a complete circumferential cement mantle discontinuity. For the 37 well-performing stems, continuous but small migration was measured between 2 and 12 years of follow-up. Continued subsidence of 0.08 mm/year (95% CI: 0.05–0.12, p < 0.001) was seen in combination with continued rotation in retroversion of 0.07°/year (95% CI: 0.02–0.12, p = 0.01). At 10 years of follow-up, mean subsidence was 2.1 (SD 1.2) mm and mean retroversion was 1.8° (SD 2.0). Two-thirds of this occurred during the first 2 postoperative years. In the 3 stems with a complete circumferential cement fracture, a sudden and disproportionately high increase in subsidence was measured in the time period of occurrence. The Exeter femoral stem continues to migrate during the first decade after implantation. Absolute stability is not required for good long-term survival if this is compatible with the design of the implant.

Partial Text

The patients in a previously reported, prospective, randomized double-blind study (Nelissen et al. 2005) on the short-term migration of the Exeter total hip arthroplasty (THA) fixated with a high- or a low-viscosity bone cement (Simplex AF and Simplex P, respectively; Stryker-Howmedica Inc., Kalamazoo, MI) remained under clinical and RSA follow-up in order to assess the long-term migration pattern and clinical outcome of the Exeter THA. In the present study we concentrated on the femoral component.

We found that the Exeter femoral stem continues to migrate during the entire first decade after implantation. After the initial period of 2 years, in which around two-thirds of the total migration was measured, the stem continued to subside and rotate into retroversion during the following 10 years.

 

Source:

http://doi.org/10.3109/17453674.2012.672093