BACKGROUND Radial head fractures constitute approximately one-third of all elbow fractures, significantly impacting the young and active population. While open reduction and internal fixation is the preferred treatment for displaced fractures, its high complication rate in comminuted fractures has led to the increasing use of radial head arthroplasty (RHA). RHA provides improved functional outcomes with fewer complications, yet its long-term efficacy remains a topic of debate. AIM To evaluate the functional outcomes of patients undergoing RHA with a modular metallic prosthesis for comminuted Mason type III and IV radial head fractures. METHODS A prospective and retrospective hospital-based study was conducted at Dayanand Medical College and Hospital, Ludhiana over 32 months (January 2021-August 2023). A total of 26 patients with Mason type III and IV fractures were included, with six retrospective and 20 prospective cases. Functional outcomes were assessed using the Mayo Elbow Performance Score (MEPS), elbow range of motion, pain via Visual Analog Scale, and activities of daily living at immediate postoperative, three-month, and six-month follow-ups. RESULTS MEPS at 6 months follow up for 4 cases (15.38%) had good scores, and 22 cases (84.62%) had excellent scores, with a mean +/- SD of 97.31 +/- 6.67. Comparisons showed significant improvement from immediate post-operative to 3 months (P < 0.0001), from immediate post-operative to 6 months (P < 0.0001), and between 3 months and 6 months (P < 0.0001). None of the patients had elbow instability after radial head replacement and 22 cases (84.62%) had no complications, while 3 cases (11.54%) had a stiff elbow, and 1 case (3.85%) had heterotopic ossification. CONCLUSION RHA is an effective treatment for comminuted radial head fractures, providing stable elbow function with minimal complications.