Introduction: Osteoarthritis is the result of mechanical and biological events that destabilize the normal processes of degradation and synthesis of articular cartilage chondrocytes, extracellular matrix, and subchondral bone. All-polyethylene (AP) tibial components were largely abandoned in favour of metal-backed (MB) components in the 1980s. metal backing is now the predominant design in total knee arthroplasty (TKA). The present study aimed to assess and compare the functional outcome, in patient with total knee replacement using all polyethylene and metal backed tibial prosthesis in Primary Total Knee Replacement. Material And Methods: Our is an analytical cross-sectional study in which we have included 36 patients with primary knee osteoarthritis kellgren –lawrence grade III, IV 18 patients in all poly group and 18 patients in metal backed group. In which during follow up X-rays and functional outcome was evaluated using the American Knee Society Score at 1, 3, and 6-month follow-ups for patients of both the groups and compared. Result: In all polyethylene groups the functional score at 1, 3 and 6 months were 51.39 + 8.1, 76.67 + 8.1 and 89.72 + 4.6 respectively. While in metal group, the mean functional scores were 50.28 + 5.8, 77.22 + 5.7 and 988.61 + 4.1 at 1 month, 3 months and 6 months respectively. The most common complication was stiffness in 13.9% of patients of both the groups followed by extension leg (5.6%), infection (2.8%) and proximal tibial fracture (2.8%) in both groups. In present study, 75% of the patient did not have any post operative complications among all study subjects. Conclusion: There is no statistically significant difference in clinical outcome between all polyethylene and metal backed, improved values in terms of functional and clinical scores preferably in both the group metal backed and all polyethylene group. This study is not without limitations. Even though it is prospective study, patients were followed for shorter duration only. Hence, a study with elegant methodology and long follow up period can accurately assess the efficacy of all polyethylene and metal backed prosthesis used in knee replacement surgery.