Introduction: Osteoarthritis (OA) knee is one of the major cause of disability particularly in the elderly .Management of OA knee with intraarticular Platelet Rich Plasma (PRP) is an emerging new technique. Aim : Aim of our study was to assess the efficacy of intra-articular injection of platelet rich plasma (PRP) in knee osteoarthritis and to investigate the correlation between risk factors likeBody mass index ,ageandseverity of osteoarthritis with clinical outcome after intraarticular injection of platelet rich plasma Study setting : Department of Physical Medicine and Rehabilitation,Government Kilpauk medical college, Chennai, India, from March 2021 to January 2022. Materials and methods : 64 patients with mean age of 56.52 ±7.53 who were diagnosed with grade 1 and 2 knee OA and who had undergone 2 doses of intraarticular injection of PRP were selected for the study and we retrospectively analysed the role of age, BMI, and Kellgren Lawrence grade of OA knee and their correlation with clinical outcome after intervention .Outcome measures used wereVAS and WOMAC scores Results: VAS and WOMAC scores before the procedure and final outcome after procedure using wilcoxn signed rank test showed that there was significant improvement in the outcome scores measured at followup done at 4th month . Subgroup analysis of patients stratified for age, Body mass index (BMI) and, KLgradewas performed for determining the individual effect of each risk factor on the outcome scores . It is found that the effect of PRP on people with BMI less than 25 ,KL grade 1 and age group <60 ,is significantly better than subjects with BMI more than 25 ,KL grade 2 and age group > 60 years. Conclusion: The use of intraarticular platelet-rich plasma definitely improves functional outcome in patients with OA and results in improved quality of life. Higher KL and risk factors like increased age, and BMI, has shown poorer outcome when compared to younger subjects , with lower BMI and KL grade , and hence modification in treatment protocol can be considered for such patients.