Arthroscopic Microdrilling for Full-thickness Trochlear Cartilage Defects in Patients Undergoing High Tibial Osteotomy Confers Improved Cartilage Status at 1 year and Rate of Minimal Clinically Important Difference at Short-term Follow-up.

Purpose: To compare the patient-reported outcome improvements and cartilage status of trochlear cartilage defects (TCDs) after additional arthroscopic microdrilling versus no treatment for TCDs during medial open-wedge high tibial osteotomy(MOWHTO) METHODS: Patients who underwent MOWHTO with either microdrilling (Group M) or no treatment (Group N) for near full-thickness TCDs (International Cartilage Repair Society[ICRS] grade≥3B) from March 2010 to September 2022 were retrospectively reviewed, with a minimum 2-year follow-up. 1:1 Propensity score matched-Group N was created. Comparative analyses were conducted using patient-reported outcomes(PROs) and minimal clinically important difference (MCID). Trochlear cartilage status was visually assessed via second-look arthroscopy 1 year postoperatively and categorized as deteriorated, maintained, or improved.

Results: Overall, 30 for group M and 84 patients for group N were included. The mean follow-up period of the matched groups was 32.8 and 32.0 months for groups M and N. The preoperative and postoperative radiographic parameters did not differ between the groups (Kellgren-Lawrence grade, pre- and postoperative alignment, medial proximal tibia angle). Both groups achieved significant clinical improvement in patients with medial compartment osteoarthritis and combined full-thickness TCD (p<0.001). PROs and improved PROs at final follow-up were not significantly different between groups, except for the Final Kujala anterior knee pain scale (70.4 [95% CI: 66.0-74.8] vs. 59.8 [95% CI: 53.0-67.6], p=0.018). MCID achievement rates in pain visual analogue scale (VAS), Knee injury and Osteoarthritis Outcome Scores (KOOS)-Pain, and KOOS-activity of daily living (ADL) were significantly higher in group M compared to group N (VAS, 93.3% vs. 63.3%, p=0.005; KOOS-Pain, 96.7% vs. 80.0%, p=0.044; KOOS-ADL, 86.7% vs. 63.3%, p=0.037). A significantly larger proportion of patients in group M demonstrated improvement in their TCD status compared to those in group N (93.1% vs. 44.8%, p<0.001).

Conclusion: Arthroscopic microdrilling for near full-thickness TCD during MOWHTO improved trochlear cartilage status at 1 year but did not enhance final PROs at short-term follow-up, though it increased MCID achievement rates in some PROs (VAS, KOOS pain, KOOS ADL) compared to untreated patients.

Level Of Evidence: Level III, therapeutic retrospective cohort study.