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Medial open-wedge high tibial osteotomy impacts patellofemoral joint alignment, cartilage
According to recently published results, medial open-wedge high tibial osteotomy adversely affected the patellofemoral joint.
“Overcorrection causing excessive valgus alignment led to further progression of degenerative changes in the patellofemoral joint and inferior clinical outcomes,” the authors wrote. “The postoperative weight-bearing ratio can be used as a predictive factor for deterioration of the cartilage status in the patellofemoral joint after [medial open-wedge high tibial osteotomy].”
Researchers retrospectively investigated 135 patients who underwent medial open-wedge high tibial osteotomy. Patients were grouped as having undercorrection, acceptable correction or overcorrection based on the postoperative weight-bearing line ratio. During implant removal at 2 years after surgery, the postoperative change in cartilage status was arthroscopically evaluated. At the mean follow-up of 52.1 months, clinical and radiological outcomes were assessed. Factors that impacted deterioration of the patellofemoral joint cartilage status were determined with regression analysis. A receiver-operating characteristic curve was used to identify the cutoff point of where the postoperative weight-bearing ratio correlated with the deterioration of cartilage status in the patellofemoral joint.
Results showed progression of cartilage degeneration in 39.3% of patients in the femoral trochlea and in 23.7% of patients in the patella. The overcorrection group had a significantly higher incidence of cartilage progression compared with the undercorrection and acceptable correction groups. Patients in the overcorrection group had significantly worse function scores, which included the Lysholm knee score, KOOS and the Shelbourne and Trumper score.
The postoperative weight-bearing ratio had a significant impact on cartilage deterioration, according to results of a regression analysis. The cutoff point for correlation of the postoperative weight-bearing ratio with International Cartilage Repair Society grade progression was 62.1% and 62.2% for the femoral trochlea and patella, respectively. – by Monica Jaramillo
Disclosures: The authors report no relevant financial disclosures.
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In their study, Yoon and colleagues evaluated the effect of medial open-wedge high tibial osteotomy (HTO) on the patellofemoral joint in a cohort of 135 patients. Using measurements of postoperative weight-bearing line ratios, they categorized the knees into undercorrected, acceptable and overcorrected groups. Based on second-look arthroscopy at 2 years and both clinical and radiographic assessment at 4 years, they reported that progression of cartilage degeneration in the patellofemoral joint was significantly greater in the overcorrected group (weight-bearing line ratio >66.3%) than in the undercorrected and acceptable correction groups. They furthermore reported that functional outcomes scores were worse in the overcorrected group.
This study highlights the effect that coronal realignment procedures such as HTO can potentially have on the patellofemoral compartment. Particularly in the setting of overcorrection, the relative distalization and lateralization of the tuberosity that occurs with increased knee valgus may play a role in patellofemoral disease progression. While it is unknown whether these increased changes occur purely as a result of coronal overcorrection or in combination with the presence of other anatomic risk factors and rotational abnormalities, the authors remind us that it is important to remember the interrelatedness and potential consequences on the patellofemoral joint when considering such procedures. Furthermore, their application of the weight-bearing line ratio may provide another useful tool in the assessment of lower extremity malalignment as it relates to patellofemoral disease.
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