How do cemented short Exeter stems perform compared with standard-length Exeter stems? The experience of the New Zealand National Joint Registry

Abstract

a b s t r a c tBackground: The standard Exeter (Stryker) cemented stem is 150 mm long with standard offsets ranging from 37.5 mm to 56 mm. Exeter short stems of 125 mm are also available in the offsets of 37.5 mm, 44 mm, and 50 mm. In addition, smaller (125 mm or shorter) Exeter cemented stems with offsets of 35.5 mm or less are available. The aim of this study was to examine the New Zealand Joint Registry (NZJR) comparing medium-term survival rates and functional outcomes of standard-length stems with Exeter short stems of various offsets in patients undergoing primary total hip replacement. Methods: Using the NZJR, we compared the results of 3 separate groups of patients with Exeter stems. Patients with standard 150 mm length Exeter stems (Standard) were compared with patients with Exeter 125 mm stems with regular 37.5 mm, 44 mm, and 50 mm offsets (Short 37þ) and Exeter 125 mm stems with offsets of 35.5 mm and below (Short 37À). Demographic data, preoperative diagnosis, patient-reported outcome measures, and reasons for revision were compared between groups. Kaplan-Meier survival analysis and Cox multivariate regression analysis were used to examine implant survival and the influence of stem group on revision rates adjusting for gender, age, diagnosis, and surgical approach. Short 37 þ groups compared with the Standard group (Standard BMI, 28.71; SD 5.72; Short 37þ BMI, 29.69; SD, 6.67; Short 37À BMI, 29.09; SD 7.07; P < .001). The all-cause revision rate for standard stems was 0.55/100 component years (cy) (95% CI: 0.52 to 0.58). The Short 37À group had a higher rate of revision compared with the Standard group (hazard ratio 1.6; 95% CI: 1.3 to 1.98; P < .001), while the Short 37þ group had a hazard ratio of 0.84 (95% CI: 0.38 to 1.88; P ¼ .674) compared with the Standard group. Cox regression analysis controlling for age, gender, diagnosis of OA, and surgical approach did not affect these findings. However, no clinically meaningful difference between Oxford hip scores was observed. Conclusions: There was a significant difference in revision rates for aseptic loosening with standard-length Exeter stems having a lower revision rate than short Exeter stems with offsets 35.5 mm or less. The Short 37þ groups, despite comprising relatively small numbers, performed similarly to the Standard stem group.

Patient-Reported Outcome Measures in High-Risk Medical Device Registries: A Scoping Review

“…This was followed by the visual analog scale (VAS) for both orthopedic and cardiac registries, which measures pain ( n = 14 28 , 43-47 , 50-52 , 54-58 and n = 3, 67 , 88 , 89 respectively). The Oxford knee score ( n = 14) 30-34 , 40 , 41 , 64 , 73-75 , 77 , 85 , 92 and Oxford hip score ( n = 12) 28 , 35-39 , 69 , 70 , 75 , 76 , 78 , 85 were also used frequently by orthopedic registries. Beyond these tools, there was wide variation in tools used.…”

Analysis of the Exeter V40 femoral stem prosthesis fracture

“…Large NJR studies comparing short and standard Exeter stem survivorship (Exeter V40 and Universal stem systems) for primary THA medium-term outcomes report contrasting outcomes for all cause revision rate. 31 , 32 Choy et al’s 31 Australian NJR (1999 to 2010)-based study demonstrated no significant difference (3.4% vs 3.5% at seven years from implantation). Conversely, Wyatt et al’s 32 review of the New Zealand NJR (1998 to 2018) concluded there was a significantly higher all-cause revision rate for short-stems (0.92/100 vs 0.55/100 components-per year) and specifically for aseptic loosening cohort (19.6% vs 7.2%).…”

“…Conversely, Wyatt et al’s 32 review of the New Zealand NJR (1998 to 2018) concluded there was a significantly higher all-cause revision rate for short-stems (0.92/100 vs 0.55/100 components-per year) and specifically for aseptic loosening cohort (19.6% vs 7.2%). Interestingly, Wyatt et al 32 reported no femoral implant fractures (41,854 THAs), whereas Choy et al 31 reported ten standard stem (0.03%) and one short stem (0.07%) fractures (36,266 THAs).…”

“…The shorter Exeter stems were designed to address femora geometries that are tighter, fluted, or smaller, and subsequently have higher prevalence in treatment of dysplastic hips. 32 It is likely underlying diagnosis also impacts implant survivorship. This may have impacted two (17%) of our short-stem fractures, primary arthroplasty performed for inflammatory arthritis and developmental dysplasia of the hip.…”

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

“…A study looking at the New Zealand National Joint Registry also investigated outcomes of short Exeter stems, but did not specifically look at the 44/00/125 revision stem which is the focus of our study. 22 The introduction of the Exeter short stem line extension in 2014 has led to further studies looking at outcomes of these. It is important to emphasize that these short stems with varying geometry and offset are different from the focus of our study, which is the 44/00/125 cement-in-cement revision stem.…”