Context: A range of motion (ROM) after complete knee arthroplasty has been hypothesized to benefit from posterior slope. Aims: Accuracy evaluation of a <3°, 3-6°, and a >6° degrees posterior sloped cutting guide and the effect of the posterior tibial slope on postoperative ROM. Settings and Design: A prospective interventional study conducted at Department of Orthopaedics, Dr. Babasaheb Ambedkar Central Railway Hospital, Byculla. Methods and Material: Seventy-five consecutive patients underwent TKA using a cutting block and intramedullary cutting guide designed to impart a <3° degrees posterior tibial slope (Group I, n=40). A 3-6° degrees tibia cutting block was used in 24 subsequent patients (Group II, n=24) and a >6° tibia cutting block was used in 11 patients (Group III, n=11). Statistical analysis: Frequency, percentage and ANOVA were used for qualitative data and mean, and standard deviation were used for quantitative data. Results: VAS score at different intervals from preoperative to post-operative periods showed significant findings up to 6 months follow-up, however, group III showed insignificant findings at 6 months to the one-year interval. Similarly, WOMAC score at different intervals showed statistically significant in the initial 6 months in all three groups except in group III from 6 months to 1 year interval which is insignificant. There was statistical significance in all three groups for the forgotten score (FJS) and knee society score (KSS) at all time intervals. Conclusions: For an effective functional result, we recommend a PTS of less than 3° and between 3-6° can be recommended for TKA.