Hybrid closed wedge high tibial osteotomy is associated with short-term arthroscopic changes in the patellofemoral joint

Hybrid closed wedge high tibial osteotomy (HCWHTO) has been reported to influence patellofemoral (PF) joint status; however, macroscopic cartilage changes remain insufficiently documented. This study aimed to evaluate 1-year arthroscopic changes in trochlear cartilage after HCWHTO and to examine their association with 2-year clinical outcomes. Between July 2011 and May 2016, 77 patients (102 knees) underwent primary HCWHTO at our institution. Of these, 61 patients (81 knees) had complete second-look arthroscopy at approximately one year postoperatively and clinical and radiographic follow-up at a minimum of two years. These cases constituted the final analysis cohort. Preoperative radiographic severity was assessed using the Kellgren–Lawrence classification. All included knees were classified as grade 3 or 4. Cartilage status was assessed arthroscopically at approximately 1 year postoperatively using the International Cartilage Repair Society (ICRS) grading system. All analyses were performed on a per-knee basis. All included knees were classified as Kellgren–Lawrence grade 3 or 4. At 1-year follow-up, 37.0% of knees demonstrated macroscopic cartilage surface improvement in the trochlear groove, whereas deterioration was observed in 6.2%. Although the median ICRS grade of the trochlea remained unchanged, the distribution shifted toward lower grades (p < 0.01). The medial patellar facet showed a slight improvement in median ICRS grade, while the lateral facet remained largely unchanged. All J-KOOS subscale scores improved significantly at 2 years postoperatively (p < 0.001). No significant correlation was observed between arthroscopic cartilage changes and improvements in clinical outcomes. In knees with complete 2-year follow-up, HCWHTO was associated with macroscopic cartilage surface changes, including redistribution toward lower ICRS grades in the trochlea at 1 year after surgery. However, these changes were not significantly correlated with clinical outcomes at 2 years postoperatively.