Structural Gains Without Symptomatic Benefit After Microfracture During High Tibial Osteotomy.

Abstract

Background: High tibial osteotomy (HTO) realigns the mechanical axis and reduces medial compartment overload in knee osteoarthritis. Microfracture (MFx) is often added to stimulate cartilage repair, yet whether MFx provides additional clinical benefit in the degenerative osteoarthritic environment remains uncertain. Emerging evidence suggests that structural cartilage changes do not consistently correlate with symptoms, raising the possibility of structure-symptom discordance.

Purpose/hypothesis: The purpose of this study was to evaluate whether MFx performed during HTO improves cartilage regeneration and postoperative patient-reported outcomes and to determine whether structural improvement corresponds with symptomatic benefit. It was hypothesized that MFx would enhance cartilage regeneration and lead to superior clinical outcomes compared with HTO alone.

Study design: Cohort study; Level of evidence 3.

Methods: A total of 62 patients who underwent navigation-assisted medial opening-wedge HTO with second-look arthroscopy at 2 years were included. Patients were categorized into 2 groups: HTO alone (group 1; n = 30) and HTO with MFx for well-shouldered focal defects (group 2; n = 32). Cartilage status was graded using the International Cartilage Regeneration & Joint Preservation Society (ICRS) system, and improvement was defined as a decrease in grade. Clinical outcomes were assessed at 2 years using the International Knee Documentation Committee (IKDC) subjective score. Group comparisons, correlation analyses, and multivariable linear regression were performed to determine independent predictors of postoperative IKDC score.

Results: Cartilage improvement occurred in 33.3% of group 1 and 62.5% of group 2 (P = .04). In the MFx group, patients achieving low-grade postoperative lesions (ICRS 1-2) had significantly smaller initial defects (2.0 vs 6.0 cm²; P < .01). Despite better structural improvement, no significant between-group difference in 2-year IKDC score was found (55.2 vs 50.6; P = .26). MFx was identified as an independent negative predictor of postoperative IKDC score (β = -14.4; P = .01). Changes in cartilage status (ΔICRS) were not correlated with symptomatic improvement (ΔIKDC; ρ = -0.18; P = .14), demonstrating a structure-symptom discordance.

Conclusion: MFx performed during HTO improved cartilage morphology but did not yield superior clinical outcomes. MFx was associated with significantly lower adjusted IKDC scores, and structural improvement did not correlate with symptomatic benefit.