Background <p>Pain catastrophizing is linked to patient-reported outcomes in knee osteoarthritis (OA) patients, but its correlation with objective joint-level function (range of motion and strength) and gait patterns is unclear. This study examined the association between objective knee function, gait patterns, and pain catastrophizing in severe knee OA patients.</p> Methods <p>This cross-sectional study included patients with knee OA admitted for total knee arthroplasty over a 3-year period from November 2016. Medical records and instrumentation databases were assessed. Patients who completed the Pain Catastrophizing Scale (PCS) were categorized into high PCS (scores ≥ 30) and low PCS (scores </p> Results <p>The analysis included 63 patients with 75 knees divided into 60 knees in the high-PCS group and 15 knees in the low-PCS group. No significant differences were found in objective knee function and gait parameters between the groups. Regression analysis showed no association between PCS and gait variables or objective knee function.</p> Conclusions <p>No significant associations were observed between pain catastrophizing and objective knee function (range of motion and muscle strength) or knee biomechanics during gait in patients with severe knee OA. These findings suggest that these aspects may be independently evaluated in the clinical assessment of disability in this population.</p>