Better functional scores at 5 years following TKA with unrestricted kinematic alignment using medial‐pivot versus ultracongruent implants

PURPOSE: The purpose was to compare patient-reported outcome measures (PROMs) at 5 years following total knee arthroplasty (TKA) using unrestricted kinematic alignment with ultracongruent (UC) versus cruciate-sacrificing medial pivot (CS-MP) and versus cruciate-retaining medial pivot (CR-MP) designs. METHODS: This was a retrospective analysis of a consecutive cohort of 140 TKAs with UC (n = 44), CS-MP (n = 44) and CR-MP (n = 52). Of the initial cohort, three died, leaving a final cohort of 137 (UC, n = 43; CS-MP, n = 44; CR-MP, n = 50). Patients completed pre- and post-operative questionnaires of the Knee Society Score (KSS 2011) Symptoms, Satisfaction, Expectations and Function components, the Kujala score and the Forgotten Joint Score (FJS). Multivariable analyses were performed to assess the association of implant type (CR-MP, CS-MP and UC) with postoperative Kujala score and FJS, adjusting for patient characteristics (age, body mass index [BMI], sex, preoperative phenotype, expectations and Wiberg classification). RESULTS: Postoperative Kujala scores were significantly better for CR-MP and CS-MP (80.1 ± 9.8 and 82.1 ± 9.8) compared to UC (73.3 ± 14.4; p = 0.007 and p < 0.001). After adjusting for patient factors, multivariable analysis revealed a statistically significant negative association between postoperative Kujala scores and UC (β = -6.270; p = 0.011). Postoperative FJS was significantly better for CS-MP compared to UC (88.9 ± 11.5 vs. 74.9 ± 23.4; p = 0.024). After adjusting for age and sex, multivariable analysis did not reveal a statistically significant association between postoperative FJS and UC (β = -6.58; p = n.s.). CONCLUSION: At 5-year follow-up, TKA using unrestricted kinematic alignment with MP designs achieved superior functional outcomes compared to UC designs, but no significant difference between CS-MP and CR-MP designs. LEVEL OF EVIDENCE: Level III.