<p>Posterior wall fractures, commonly caused by high-energy mechanisms like motor vehicle collisions or falls, are frequently associated with hip dislocation and complex intra-articular injuries. Despite surgical advances, post-traumatic osteoarthritis (PTOA) remains a prevalent complication, often leading to significant functional impairment and eventual joint replacement. Identifying potentially modifiable risk factors may help improve long-term outcomes. This study aimed to identify independent risk factors associated with the development of post-traumatic osteoarthritis (PTOA) following surgical treatment of posterior wall acetabular fractures. A multicenter retrospective cohort study was conducted on 159 patients with isolated posterior wall acetabular fractures treated with open reduction and internal fixation between January 2017 and June 2023. All patients had a minimum of 24 months of clinical and radiographic follow-up. Univariate and multivariate logistic regression were used to analyze potential risk factors. The overall incidence of PTOA was 23.9%, with a median onset of 18 months after surgery. Multivariate logistic regression analysis identified fracture comminution, joint surface impaction, femoral head necrosis, non-anatomical reduction, posterior wall defect ≥ 50%, and delayed surgical intervention (&gt; 2 weeks) as factors independently associated with an increased risk of PTOA (all <i>p</i> &lt; 0.05). In addition, longer surgical duration was associated with a higher likelihood of PTOA. Multiple factors were independently associated with the development of post-traumatic osteoarthritis following posterior wall acetabular fractures, including fracture comminution, articular surface impaction, reduction quality, femoral head necrosis, posterior wall defect, and delayed surgical intervention. Anatomical reduction and earlier surgery were associated with a lower risk of PTOA in this cohort. These findings may assist in risk stratification and perioperative decision-making.</p>