Lateral knee osteoarthritis (OA) is common after anterior cruciate ligament reconstruction (ACLR), yet gait characteristics associated with lateral knee OA after ACLR are not well understood. This cross-sectional study aimed to compare knee, trunk, pelvis, hip, and ankle kinematics and moments between people with predominant lateral knee OA after ACLR and healthy controls.Nineteen post-ACLR people with lateral knee OA and 25 healthy controls were recruited. Quantitative gait analysis was conducted during walking, and knee pain, confidence, and kinesiophobia were assessed. Between-group differences in peak kinematics and moments were evaluated, and Pearson correlations evaluated relations between biomechanical and patient-reported measures (P < 0.05).Participants with lateral knee OA after ACLR had greater peak knee flexion (mean difference, 3.5°; 95% confidence interval, 0.9-6.1) and lower knee internal rotation angles (-3.3°; -6.2 to -0.5) than the controls. Those with lateral knee OA also had greater peak pelvic anterior tilt (3.1°, 0.4-5.9), hip flexion angles (5.1°, 1.9-8.3), and peak ankle dorsiflexion moment (0.1 N·m·kg(-1), 0.0-0.2). In the lateral knee OA group, worse knee confidence and kinesiophobia were significantly correlated with greater peak trunk flexion angle (r = 0.654 and r = 0.535, respectively) and greater knee pain was significantly correlated with greater peak knee flexion angle (r = 0.535).Gait characteristics associated with lateral knee OA after ACLR differ from those in healthy individuals, predominantly in the sagittal plane. Increased sagittal plane knee and trunk kinematics seem to be related to worse knee pain, confidence, and kinesiophobia. These findings will assist the development of compartment-specific interventions for individuals with posttraumatic lateral knee OA.