Aim: To compare the American Orthopedic Foot and Ankle Society score between the use of anterior to posterior lag screws and posterior buttress plating for fixing the posterior malleolus in tri-malleolar ankle fractures. Material and methods: The research included a total of 60 patients who had ankle fractures. These patients were separated into two groups, with each group consisting of 30 instances. Group A was treated with AP lag screw fixation, while group B got posterior buttress plating. The research comprised patients who had posterior malleolar fracture in tri-malleolar fractures with displacement more than 2 mm, ankle instability, and fracture occurring within 14 days. The patients were 18 years or older at the time of surgery and had provided permission to participate in the study were included. The ultimate assessment included AOFAS scores, which classified outcomes into several categories based on a numerical range. These categories included outstanding (90-100), good (80-89), fair (70-79), and bad (below 70). The evaluation focused on three subcategories: pain (rated out of 40), function (rated out of 45), and alignment (rated out of 15). Results: The clinical outcomes measured by the American Orthopedic Foot and Ankle Society (AOFAS) score shows that pre-operatively, the scores were similar between the two groups (42.8 ± 8.1 for AP Lag Screw vs. 43.1 ± 7.9 for Posterior Buttress Plating, p = 0.84). At 6 weeks post-operatively, the Posterior Buttress Plating group had a higher mean AOFAS score (62.3 ± 8.8) compared to the AP Lag Screw group (58.5 ± 9.2), though the difference was not statistically significant (p = 0.21). By 12 weeks, the trend continued, with the Posterior Buttress Plating group scoring higher (75.2 ± 9.9 vs. 70.4 ± 10.5), but still not significantly different (p = 0.15). However, at 18 weeks, a significant difference emerged, with the Posterior Buttress Plating group achieving a mean AOFAS score of 84.1 ± 8.3 compared to 78.2 ± 8.9 in the AP Lag Screw group (p = 0.04). This indicates that the Posterior Buttress Plating technique may offer better long-term clinical outcomes. Conclusion: The results of this research suggest that patients who have been diagnosed with tri-malleolar ankle fractures have better postoperative AOFAS ratings during follow-up when the posterior malleolus is treated with posterior buttress plating, rather than AP screws. The findings highlight the potential benefits of using posterior buttress plating in these circumstances to improve the patients' surgical outcomes and overall recovery.