Satisfactory Results of the Exeter Revision Femoral Stem Used for Primary Total Hip Arthroplasty

Survival of the Exeter V40 short revision (44/00/125) stem when used in primary total hip arthroplasty

The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in 'cement-in-cement' revision cases. It has, however, been used 'off-label' as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR. We analyzed 328,737 primary THAs using the Exeter V40 stem, comprising 34.3% of the 958,869 from the start of the NJR to December 2018. Our exposure was the stem, and the outcome was all-cause construct revision. We stratified analyses into four groups: constructs using the 44/00/125 stem, those using the 44/0/150 stem, those including a 35.5/125 stem, and constructs using any other Exeter V40 stem. In all 328,737 THAs using an Exeter V40 stem, the revision estimate was 2.8% (95% confidence interval (CI) 2.7 to 2.8). The 44/00/125 stem was implanted in 2,158 primary THAs, and the ten-year revision estimate was 4.9% (95% CI 3.6 to 6.8). Controlling for age, sex, year of operation, indication, and American Society of Anesthesiologists grade demonstrated an increased overall hazard of revision for constructs using the 44/00/125 stem compared to constructs using other Exeter V40 femoral stems (hazard ratio 1.8 (95% CI 1.4 to 2.3)). Although the revision estimate is within the National Institute for Health and Care Excellence ten-year benchmark, survivorship of constructs using the 44/00/125 stem appears to be lower than the rest of the range. Adjusted analyses will not take into account 'confounding by indication', e.g. patients with complex anatomy who may have a higher risk of revision. Surgeons and patients should be reassured but be aware of the observed increased revision estimate, and only use this stem when other implants are not suitable.

Analysis of the Exeter V40 femoral stem prosthesis fracture : systematic review and single centre case series

Aims

The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems.

Methods

A systematic literature search was performed adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. In parallel, we performed a retrospective single centre study of Exeter V40 femoral stem prosthetic fractures between April 2003 and June 2020.

Results

There are 25 reported cases of such prosthetic fractures confined to small case series and case reports within the literature. We report an additional 19 cases to the literature (mean age 66.3 years (SD 11.7); 12 (63%) females; BMI 32.9 kg/m² (SD 5.9)). The mean time from index procedure to fracture was 7.8 years (SD 3.6; 2.5 to 16.3). Exeter V40 stem fracture incidence was 0.15% and 1.21% for primary and revision arthroplasty, respectively. Incidence was significantly higher in revision arthroplasty (p < 0.001) and 125 mm length stems compared to ≥ 150 mm length stems (1.25% vs 0.13%, respectively; p < 0.001). When comparing different stem length cohorts, 125 mm short-stems were associated with stem-body fractures (92% vs 29%; p = 0.0095), earlier time to fracture (6.2 years vs 11.0 years; p = 0.0018), younger patient age at time of fracture (62.7 years vs 72.6 years; p = 0.037), and female sex (75% vs 43%; p = 0.326).

Conclusion

This complication remains rare, although we report a significantly higher incidence at up to 17 years follow-up than in the literature. Short 125 mm length Exeter V40 stems undoubtedly have a role in restoring anatomy and biomechanics in smaller femoral geometries, although the surgeon has to appreciate the higher risk of stem fracture and the associated predisposing factors which may necessitate particular attention to surgical technique and planning.

Cite this article: Bone Jt Open 2021;2(6):443–456.

The Exeter Short Revision Stem for Cement-in-Cement Femoral Revision: A Five to Twelve Year Review

BACKGROUND

Cement-in-cement femoral revision is a proven technique in revision total hip arthroplasty, with excellent results reported using standard-sized Exeter stems. The Exeter 44/00/125 short revision stem was introduced in 2004 to facilitate cement-in-cement revision. The stem is 25-mm shorter and has a slimmer body than standard stems to facilitate adjustment of depth of insertion and stem version. It is not known if this change in stem size affects its long-term performance. We therefore reviewed the outcome of all Exeter short revision stems used for cement-in-cement revision in our unit, with a minimum of 5 years of follow-up.

METHOD

One hundred sixty-six cases were performed between 2004 and 2010. Mean follow-up of surviving patients was 8.1 years (range 5.0-11.7). The fate of all 166 hips were known and included in the survival analysis.

RESULTS

Median clinical scores improved significantly. Sixteen hips required re-revision (infection 6, loose cup 3, periprosthetic fracture 3, instability 2, stem fracture with chronic infection 1, and pain 1). Kaplan-Meier survival analysis at 10 years revealed 100% survival for aseptic stem loosening, 96.8% survival for stem failure, and 88.9% survival for all causes.

CONCLUSION

The Exeter short revision stem performed as well as standard length stems for cement-in-cement revision in this the largest and longest review of their use. Larger registry-based studies may provide additional information on the performance of this stem.