A 15-year evaluation of two total knee arthroplasty designs : similar patient-reported outcomes and survivorship but divergent patellofemoral and radiological outcomes
In brief
Kinemax knees had 3 times the odds of anterior pain, with similar 15-year scores
In a randomized comparison, the two knee implants had similar patient-reported scores and revision rates at 15 years. Kinemax recipients had higher odds of anterior knee pain, tibial radiolucent lines and severe kneecap-joint arthritis, though pain differences did not translate into meaningfully different overall scores. Only 61 patients completed 15-year functional assessments, limiting how confidently the findings apply.
- Journal
- Bone & joint open (Q1)
- Published
- 14 October 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Nick D Clement, Thomas R Williamson, Gillian L Leitch, Chloe E H Scott, Paul Gaston
- PMID
- 42869432
- DOI
- 10.1302/2633-1462.710.BJO-2026-0115.R1
Why clinicians should know about it
- Picked for Orthopedics and Sports Medicine (paper of the day, 14 October 2026): 15‑year RCT follow‑up compares two TKA designs
Abstract
AIMS: To compare 15-year patient-reported outcomes measure (PROMs), pain characteristics, implant survivorship, and radiological findings between two total knee arthroplasty (TKA) systems to determine whether modern implant design influenced outcomes. METHODS: A minimum 15-year follow-up of a randomised controlled trial was undertaken of patients undergoing primary TKA with either the Kinemax or Triathlon implant. We compared 15-year survivorship, mortality, patient-reported outcome measures (PROMs: Oxford Knee Score (OKS), Forgotten Joint Score (FJS), EuroQol five-dimension questionnaire (EQ-5D), and EQ visual analogue scale (VAS)), pain and location, and radiological assessments between groups. RESULTS: There were nine revisions during the follow-up period (six aseptic and three septic), and there was no difference between the groups (p = 0.721, log-rank). A total of 108 deaths occurred, corresponding to 50.7% (95% CI 44.1 to 57.3) patient mortality at 15 years, with no difference between groups (p = 0.603, log-rank). Overall, 61 patients completed functional assessment at 15 years (mean age 80 years (SD 8.5); 41 female (67%)). There were no statistical (p ≥ 0.170) or clinically meaningful differences between groups in OKS, FJS, EQ-5D, EQ VAS, or satisfaction. Longitudinal analysis demonstrated no between-group differences in postoperative OKS or EQ-5D. However, both declined significantly over the study period (p < 0.001), but remained clinically meaningfully better than those observed preoperatively. Pain VAS scores were comparable, although anterior knee pain was more frequent in the Kinemax group (OR 3.2, p = 0.037). Radiological assessment showed no loosening. Tibial zone 1 radiolucent lines (OR 12.1, 95% CI 2.6 to 57.6, p < 0.001) and severe patellofemoral osteoarthritis (OR 5.1, 95% CI 1.4 to 18.4, p = 0.010) were more prevalent in the Kinemax group. CONCLUSION: Both implants were associated with comparable PROMs, and despite deterioration with increasing follow-up, they remained superior to preoperative scores. The Kinemax group demonstrated higher rates of anterior knee pain, though this difference did not result in clinically meaningful outcome disparities.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.