Patellofemoral osteoarthritis progression after open-wedge high tibial osteotomy: A two-view, morphology-based radiographic assessment and association with postoperative outcomes.

BACKGROUND

Open-wedge high tibial osteotomy (OWHTO) is an established procedure for medial compartment knee osteoarthritis. However, postoperative progression of patellofemoral osteoarthritis (PFOA) and its clinical relevance remain uncertain. The objective of this study was to determine whether radiographic PFOA progression after OWHTO is associated with postoperative patient-reported outcomes and to identify factors associated with progression.

METHODS

We retrospectively reviewed 116 knees in 104 patients who underwent OWHTO with ≥4 years of follow-up. PFOA progression could be evaluated in 114 knees (two lacked preoperative Merchant views) using a morphology-based, two-view radiographic assessment integrating Merchant and true lateral views and focusing on interval changes in osteophytes and joint-space narrowing. Knees were classified as progression (Group P) or non-progression (Group N). Clinical outcomes were assessed using the Japanese Knee injury and Osteoarthritis Outcome Score (J-KOOS). Factors associated with progression were examined using univariate and multivariable logistic regression.

RESULTS

Radiographic PFOA progression was observed in 63/114 knees (55 %). At final follow-up, postoperative J-KOOS was significantly lower in Group P for Symptoms, Pain, Activities of Daily Living, and Quality of Life, whereas Sports/Rec did not differ significantly between groups. In multivariable logistic regression, greater preoperative knee extension loss and a higher PF Kellgren-Lawrence (KL) grade were independently associated with PFOA progression.

CONCLUSIONS

Radiographic PFOA progression after OWHTO, as classified using a morphology-based two-view radiographic assessment, was associated with inferior postoperative patient-reported outcomes despite comparable improvement from baseline. Greater preoperative knee extension loss and higher PF KL grade were associated with an increased likelihood of progression and may inform preoperative counseling and surgical planning.