Introduction: The functional dysfunction in the osteoarthritis knee is caused by pain and quadriceps muscle weakness. Physiotherapy treatment includes isometric and isotonic exercises for improving joint range of motion and muscle strength of quadriceps muscle. Biofeedback can be combined with these exercises to enhance awareness about the extent of work done by the muscle. Aim: The aim of the study was to compare the efficacy of quadriceps sets with biofeedback and modified quadriceps sets with biofeedback along with ultrasound in the reduction of pain and active extension lag in knee osteoarthritis. Methodology: A total number of 30 participants were divided into group A and B, 15 each group according to inclusion and exclusion criteria using simple random sampling. Group A received quadriceps sets exercises with biofeedback and group B received modified quadriceps sets with biofeedback. Both groups also received pulsed ultrasounds prior to exercise. The outcome measures were pain and extensor lag, which were assessed at baseline and after 2 weeks of the treatment protocol. Results: Both the groups showed improvement but between-group analysis showed a significant reduction of pain (mean 1.53 right side and mean 1.73 left side, p__ampersandsignlt;.0001) and active extension lag (mean 5.33 right side and mean 6.06 left side, p__ampersandsignlt;.0001) bilaterally in group B who had received modified quadriceps sets with biofeedback when compared with group A. Conclusion: Modified quadriceps sets with biofeedback were more effective than quadriceps sets with biofeedback along with ultrasound in reduction of pain and active extension lag in knee osteoarthritis patients.