International Orthopaedics - 2026-08-07 - Journal Article
Does tibia vara increase medial knee pain following cemented mobile-bearing unicompartmental knee arthroplasty? a prospective comparative study.
Pongcharoen B, Panumaswiwat C, Promkoh S, Donnimitsakul S
Topics
Key Takeaway
Preoperative tibia vara does not increase medial knee pain or worsen any patient-reported outcome at 2 years following cemented mobile-bearing UKA, with VAS scores of 0.2 vs 0.3 (p=0.25) between tibia vara and normal tibia groups.
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Summary
This prospective comparative study asked whether preoperative tibia vara adversely affects medial knee pain and functional outcomes after cemented mobile-bearing UKA. 150 knees were stratified by tibial morphology and followed to 24 months using VAS, KSS, OKS, KOOS, FJS, and Kujala scores analyzed with generalized estimating equations. VAS for medial knee pain was not higher in the tibia vara group at any timepoint and did not differ at 2 years (0.2 vs 0.3, p=0.25); postoperative aTFA was significantly lower in the tibia vara group (0.0° vs 3.4°, p<0.001) with no complications in either group.
Key Limitation
Two-year follow-up is insufficient to assess whether the lower postoperative aTFA in the tibia vara group translates into differential implant survivorship or progressive lateral compartment loading over time.
Original Abstract
PURPOSE
To determine whether preoperative tibia vara increases medial knee pain (MKP) following cemented mobile-bearing unicompartmental knee arthroplasty (UKA).
METHODS
This prospective study included 150 knees with anteromedial osteoarthritis undergoing cemented mobile-bearing UKA (Group I: 39 tibia vara; Group II: 111 normal tibia). Primary outcome was VAS for MKP, analysed by generalized estimating equations to account for bilateral cases. Secondary outcomes included Knee Society Score, Oxford Knee Score, Knee injury and Osteoarthritis Outcome Score, Forgotten Joint Score, Kujala Score, and anterior knee pain, assessed at six weeks to 24 months.
RESULTS
VAS for MKP was never higher in Group I and did not differ at two years (0.2 ± 0.5 vs. 0.3 ± 0.7; p = 0.25); it was significantly lower in Group I at six months (0.2 ± 0.6 vs. 0.6 ± 1.3; p = 0.01), by margins below the minimal clinically important difference. Postoperative aTFA was lower in Group I (0.0° ± 2.5 vs. 3.4° ± 2.9; p < 0.001). No complications occurred in either group.
CONCLUSION
Tibia vara does not increase MKP or adversely affect short-term clinical outcomes following cemented mobile-bearing UKA.