Background There is no consensus in the literature regarding the patients with obesity who do well with TKA, or this group is at risk of a variety of complications. Implant choices between the two types of implants which either long or standard stem can improve the likelihood that a patient with obesity will achieve high scores for function and quality of life after TKA. Methods This prospective clinical study included 200 patients who were categorized into two groups: group (1) traditional (standard) unstemmed cemented tibial tray (n=100 patients) and group (2) stemmed cemented tibial tray with the cementless press-ft stem (n=100 patients). Results The average follow-up was (7.6±1 years) (range from 6.5 up to 10 years). The average age of the stemmed group was 55.69±8.45 and for the unstemmed group was 57.3±7.8. The average BMI for the stemmed patients was 38.84±3.89, while for the standard (unstemmed) group was 40.0±3.95. Functional results showed signifcant improvement in both groups but more in the stemmed group (LS) as the diference and change between pre and post were more signifcant at long stem (P> 0.001). Conclusion Based on our results, there were signifcant improvements in both groups either stemmed or unstemmed TKA but more in the stemmed group which had higher functional outcomes compared to the unstemmed group