A Randomized Controlled Trial of Kinematically and Mechanically Aligned Total Knee Arthroplasties: Long-Term Follow-Up

Abstract

Background: The optimal alignment technique for total knee arthroplasty (TKA) remains controversial. We previously reported 6-month and 2-year results of a randomized controlled trial comparing kinematically versus mechanically aligned TKA. In the present study, we report the mean 13-year (range, 12.6-14.4) follow-up results from this trial.

Methods: The original cohort included 88 TKAs (44 kinematically aligned using patient-specific guides and 44 mechanically aligned using conventional instrumentation), performed from 2008 to 2009. After institutional review board approval, the health records of the original 88 patients were queried. Revisions, reoperations, and complications were recorded. There were 26 patients who died, leaving 62 patients for follow-up. Of these, 48 patients (77%) were successfully contacted via phone. Reoperations and complications were documented. Furthermore, a battery of patient-reported outcome measures (PROMs) (including Western Ontario and McMaster University Index, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score Junior, Forgotten Joint Score, Modified-Single Assessment Numerical Evaluation, and patient satisfaction) were obtained.

Results: Of the original 88 patients in the study, 15 patients had at least one reoperation (17%) and 5 patients had undergone complete revision surgery (6%). There was no difference between the 2 alignment methods for major and minor reoperations (P = .66). The kinematically aligned total knees self-reported a nonstatistically significant (P = .16) improved satisfaction (96% versus 82%), but no difference in other PROMs compared to mechanically aligned TKAs.

Conclusion: Kinematically aligned TKA demonstrates excellent mean 13-year results, comparable to mechanically aligned TKA with similar reoperations, complications, and PROMs.

Trial registration: ClinicalTrials.gov NCT00837772.

Keywords: kinematic; kinematic alignment; total knee alignment; total knee arthroplasty; total knee replacement.