Knee osteoarthritis results in changes that affect balance. It has been reported that osteoarthritis worsens proprioception and increases the risk of falling. The objective of this study was to assess changes in balance among patients with knee osteoarthritis at 1 year after total knee arthroplasty (TKA) surgery and its relationship with clinical variables. This prospective, observational study evaluated 44 patients before and 1 year after TKA. Variables analyzed included age, body mass index, pain, range of motion for both knees, bilateral quadriceps and hamstrings muscle strength, gait velocity, and Knee Society score. Balance and posture control were assessed using the following computerized posturography tests: the weight bearing test, modified Clinical Test of Sensory Interaction on Balance (mCTSIB) test, and sit-to-stand test. Pre- and postoperative differences were analyzed using Wilcoxon and chi-square tests, and effect size was measured using standardized response mean. Correlations were assessed by the Spearman test. One year after TKA, some improvement in balance tests was observed. Significant differences were observed in the mCTSIB test: foam surface with open eyes (P≤.001), foam surface with closed eyes (P≤.001), and composite value (P≤.001). Effect size was moderate to high. Age showed significant correlation with mCTSIB composite value changes (20.369; P5.037). No significant correlations were found between posturographic tests and other analyzed variables. Balance measured by computerized posturography improved 1 year after TKA. Significant changes were observed between open and closed eyes using a foam surface for the mCTSIB test. A mild negative correlation was found between age and posturographic changes.