New and Improved? Analysis of Generational Implant-Related Failures and All-Cause Revision Indications for Total Knee Arthroplasty Over a 30-Year Period.

BACKGROUND

Modern total knee arthroplasty (TKA) implants are designed with the goal of improving patient outcomes and reducing revisions. The purpose of this study was to determine if material and technical advancements in TKA design over three decades have translated to improvements in implant-related revisions, survivorship, and patient-reported outcome measures (PROMs) at a high-volume institution.

METHODS

Prospectively collected data were queried for all primary, cemented TKAs performed by eight surgeons from February 1995 to February 2024. A total of 11,767 TKAs were included from three different manufacturers. The primary outcome was the implant-related mechanism of failure. Secondary outcomes included revision indications, survivorship using any revision as an endpoint, survivorship using aseptic revision as an endpoint, and PROMs. Patients who received older-generation implants had significantly longer mean follow-up (mean 6.6, 0 to 25.3, versus mean 2.9, 0 to 11.2 years; P < 0.01).

RESULTS

Among the 312 revisions, earlier-generation implant-related failures were most commonly due to implant loosening (1.0%), polyethylene wear (0.3%), and instability (0.3%). The most common causes for revision extrinsically were infection (1.2%), loosening (1.0%), and polyethylene wear (0.3%). The current-generation implant-related failures were most commonly due to implant loosening (0.3%), instability (0.2%), and fracture (0.1%). Reasons for all-cause revision due to extrinsic causes were most commonly due to infection (0.7%) and loosening (0.3%). Survivorship using all-cause revisions as an endpoint (P > 0.05) and using aseptic revisions as an endpoint (P > 0.05) were similar between the two generations. No clinically important differences in postoperative Oxford, Knee Society, and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores were identified between generational TKA designs.

CONCLUSIONS

At our institution, the adoption of newer TKA designs has not led to clinically important changes in the 10-year survivorship or PROMs over older generations of high-performing implants from the same manufacturers. The focus should continue to remain on improving implant design and surgical technique.