The effect of tibial component rotational alignment on clinical outcomes of mobile-bearing unicompartmental knee arthroplasty

BACKGROUND: The optimal tibial component rotational alignment in unicompartmental knee arthroplasty has not been defined. This study aimed to explore the effect of tibial component rotational alignment on the clinical outcomes of UKA. METHODS: Clinical and follow-up data from 269 patients were retrospectively analysed. They were assigned into Groups A (− 5° to 0°), B (0°–3°), C (3°–6°) and D (> 6°) according to the external rotation of the tibial component to Akagi’s line. The Knee Society Score clinical (KSS-c), Knee Society Score function (KSS-f), Forgotten Joint Score (FJS) and postoperative complications at 2 years postsurgically were analysed. RESULTS: The mean rotation of the tibial component relative to Akagi’s line in 269 patients was 4.56 ± 3.79°. There were 15, 84, 89 and 81 patients in Groups A, B, C and D, respectively. The postoperative KSS-c and KSS-f in Groups B and C were significantly higher than those in Group D. No significant differences in KSS-c and KSS-f were detected between Groups B and C. The postoperative FJS in Group B was significantly higher than that in Group C, which was significantly higher in Group C than in Group D. There were 5, 8 and 15 cases of postoperative knee pain in Groups B, C and D, respectively, and the difference was statistically significant. CONCLUSION: Tibial component rotational alignment is of significance to Oxford Phase III UKA in patients. External rotation of the tibial component by 0°–3° is optimal to achieve satisfactory clinical outcomes.