Do refinements to original designs improve outcome of total knee replacement? A retrospective cohort study

Abstract

BackgroundLong-term results of the 'classic’ low contact stress (LCS) total knee replacement (TKR) have been satisfactory; nonetheless, design changes have been made which resulted in the 'complete’ LCS TKR. The aim of this study is to compare the 5-year incidence of revision and midterm clinical performance before and after introduction of the 'complete’.MethodsA retrospective cohort analysis was conducted on 100 primary uncemented TKRs of both designs. At 5-year follow-up, revision and reoperation rates were determined for these 200 TKRs. Knee Society score (KSS), the Oxford Knee score (OKS) and range of motion were determined for 143 TKRs.ResultsIn the 'classic’ cohort, 3% of the TKRs were revised compared with 5% in the 'complete’ cohort (p = 0.72).The mean KSS was 134.1 (SD 38.3) in the 'classic’ cohort compared to 135.0 (SD 42.8) in the 'complete’ cohort (p = 0.89). Of the 'complete’ TKRs, 35.2% scored within the lowest quartile of the KSS knee compared to 16.7% of the 'classic’ TKRs (p = 0.01). The OKS was 23.3 (SD 9.3) in the 'classic’ cohort compared to 22.5 (SD 10.1) in the 'complete’ cohort (p = 0.45). More than 5° flexion contracture was only found in four patients in the 'complete’ cohort (p = 0.04).ConclusionsNo statistical difference in revision rate and average scores for midterm clinical performance was observed between the 'classic’ and the 'complete’. However, the 'complete’ cohort had a higher percentage of KSS Knee in the lowest quartile, which suggests a clinical relevant difference compared with the 'classic’. Further investigation in future studies with new designs is needed.

Cross-linked versus conventional polyethylene for total knee arthroplasty: a meta-analysis

“…The reasons for reoperation after TKA included polyethylene wear, prosthesis loosening, periprosthetic infection, mal-alignment, instability, arthrofibrosis, and periprosthetic fracture [ 33 , 34 ]. In our meta-analysis, no significant difference was observed in the incidence of reoperation between groups.…”

Does the Implant Design Influence the Outcome after Total Knee Arthroplasty ?

“…The main objectives of TKA are reduction of pain, improvement of function and correction of deformities 15 . Many studies have shown clearly that these objectives are mostly fulfilled following properly performed TKA [16][17][18] .…”

“…Unfortunately, there is no ideal rating system. However, all systems include measurement of pain severity, evaluation of function and assessment of the range of motion 16,18,19 . In our study, we have used these three assessment tools for evaluating patient's outcome postoperatively and preoperatively.…”

Functional outcome of total knee replacement: a study protocol for a prospective, double-blinded, parallel-group randomized, clinical controlled trial of novel, personalized and conventional implants

“…However, the differences between the groups were not even close to the recently described minimally clinically important difference [30]. On the other hand, one small study showed that refining a well performing knee design did not influence the functional outcome [31] . In contrast to this finding, a new design was reported to improve the OKS score of TKR patients in a cross-sectional setting [32].…”