Medial Unicompartmental Knee Arthroplasty Superiority Over High Tibial Osteotomy, Suggests Study

The clinical decision between joint preservation and arthroplasty for medial knee osteoarthritis remains a point of intense debate among orthopedic surgeons, as previous research has often struggled to define which procedure provides the best balance of patient-reported satisfaction and structural correction. This clinical gap—stemming from a lack of direct comparisons using rigorous matching and meaningful clinical thresholds—prompted Saurav Narayan Nanda and colleagues from their affiliated institution to conduct a targeted investigation to clarify these outcomes and provide clinicians with more definitive guidance on procedure selection.

Therefore, the retrospective propensity-matched study compared 52 patients (26 HTO, 26 UKA) treated for isolated medial osteoarthritis between 2016 and 2021. Over a 28.4-month mean follow-up, researchers evaluated functional outcomes using the Oxford Knee Score (primary), VAS pain, and Knee Society Score. By excluding inflammatory or multi-compartmental disease, the analysis focused strictly on surgical efficacy relative to the Minimal Clinically Important Difference (MCID) to ensure clinical relevance

Key Clinical Findings of the Study Incldes:

• Superior Functional Recovery: The study found that the UKA group achieved significantly higher OKS results compared to the HTO group (40.1 versus 34.8), a difference that successfully surpassed the established threshold for clinically meaningful improvement.

• Enhanced Mechanical Alignment: The study demonstrated that HTO provided vastly superior correction of the mechanical axis, achieving 3.9 degrees of valgus realignment compared to the minimal 0.9 degrees observed in the UKA cohort.

• Effective Pain Modulation: The study indicated that while post-operative pain reduction was statistically more favorable in the UKA group, the variance between the two surgical groups did not reach the level of a minimal clinically important difference.

• Statistically Significant Function: The study reported that KSS Function scores were higher for UKA patients; however, these statistical differences remained below the threshold required for a patient to perceive a distinct clinical advantage.

• Comparable Safety Profiles: The study observed that revision-free survival was statistically similar between both techniques, with a revision rate of 3.8% for HTO and 7.7% for UKA at the final follow-up point.

The results suggest that unicompartmental knee arthroplasty offers a more robust functional trajectory for patients over a two-year period, whereas high tibial osteotomy remains the gold standard for clinicians prioritizing the precise restoration of mechanical alignment and joint preservation.

Thus, the study concludes surgeons should aim to individualize the choice of procedure by carefully considering the patient's age, baseline activity levels, and specific expectations regarding functional recovery versus long-term joint preservation.

While the propensity-matched design provides strong evidence, the retrospective nature of the analysis and the specific cohort size represent limitations that suggest a need for larger, prospective multi-center trials to further validate these mid-term clinical findings.

Reference

Nanda, S. N., Gachhayat, A., Kaushik, S., Mishra, D., Tyagi, A., & Poddar, S. (2025). Medial Unicompartmental Knee Arthroplasty vs. High Tibial Osteotomy for Isolated Medial Knee Osteoarthritis: A Propensity-Matched Study of Clinical Outcomes. Indian Journal of Orthopaedics, 60(2), 458-464.