Preoperative knee cartilage degeneration in the patellofemoral joint results in worse clinical outcome scores 2 years after inverted V-shaped high tibial osteotomy.

PURPOSE: To determine whether preoperative whole-organ knee magnetic resonance imaging findings are associated with 2-year patient-reported outcomes after inverted V-shaped high tibial osteotomy (iV-HTO). The hypothesis of this study was that preoperative tibiofemoral cartilage wear or meniscal lesion predicts worse outcomes 2 years after iV-HTO, while patellofemoral joint degeneration does not have a significant impact.

METHODS

A retrospective review was conducted of iV-HTO cases (2015-2022) with preoperative magnetic resonance imaging and 2-year follow-up data. Whole-Organ Magnetic Resonance Imaging Score (WORMS) sub-scores for cartilage, meniscus, bone marrow lesions, cysts and effusion were recorded for each compartment. Paired t tests were used to compare preoperative and post-operative clinical and radiographic outcomes. Spearman correlations assessed associations between WORMS and Knee Injury and Osteoarthritis Outcome Score (KOOS) and Lysholm score. Multivariable linear regression analyzed predictors of 2-year KOOS Symptoms, with patellar cartilage WORMS subscale (0-12) entered a priori and adjusted for preoperative symptoms, age, body mass index (BMI) and medial femoral condyle WORMS.

RESULTS

Forty-six knees (39 patients; age, 55.5 ± 8.3 years; BMI, 27.9 ± 4.0 kg/m2) were included. The Lysholm score and KOOS improved significantly from baseline to 2 years. The post-operative hip-knee-ankle angle, weight-bearing line, femorotibial angle and medial proximal tibial angle differed significantly, while patellar height indices remained unchanged. Tilting angle and lateral shift ratio improved. There was no significant correlation between WORMS and Lysholm scores. WORMS cartilage subscale correlated negatively with KOOS Symptoms; strongest for the patella, followed by the medial femoral condyle. In the adjusted model, higher patellar WORMS independently predicted lower KOOS Symptoms at 2 years; other covariates were nonsignificant.

CONCLUSIONS

iV-HTO yields significant 2-year clinical and radiographic improvements. However, advanced preoperative patellar cartilage degeneration independently predicted worse KOOS Symptoms despite coronal realignment and enhanced patellofemoral congruity. Preoperative patellofemoral cartilage grading should guide indications, counselling and preoperative planning.

LEVEL OF EVIDENCE: Level IV, retrospective cohort study.