The World Health Organization (WHO) estimates that by 2025 about 2.3 billion adults will be overweight, with more than 700 million obese. Obese patients with joint pain and reduced physical function represent a challenging group to treat effectively. Objective: To evaluate patients undergoing bariatric surgery and the implications of this surgery on knee joint pain and to conduct anamnesis and apply specific questionnaires to deepen the discussion and elucidate the knee joint symptoms related to obesity. Methods: Observational cross-sectional study with tabulation and analysis of collected data. Results: We obtained a significant result when comparing knee pain pre and post-surgery, in which pain increased by 15.8%. Conclusion: Although worsening or maintenance of pain may occur, this fact is associated to factors such as the increase of functional activities of a joint that was previously in disuse and the loss of muscle mass as a sustainer. We concluded that the improvement of joint pain complaints were mainly due to the reduction of joint overload. Level of Evidence IV, Case Series.