Anatomical reduction of marginal impaction in posterior wall acetabular fractures ensures mid-term satisfactory outcomes

This study aimed to compare the postoperative radiological and functional outcomes of posterior wall acetabular fractures with and without marginal impaction. Patients who underwent surgical treatments for posterior wall acetabular fractures at a single level I trauma center between January 2013 and June 2022 were enrolled. Seventeen patients with marginal impaction were classified into group I, and the remaining 24 were classified into group II. Immediate postoperative reduction quality was confirmed using computed tomography (CT), final follow-up results were evaluated using simple x-ray. Heterotopic ossification (HO), post-traumatic osteonecrosis of femoral head (ONFH), rate of conversion to total hip arthroplasty (THA), and Harris Hip Score (HHS) also compared between the two groups. Marginal impaction occurred in 41.5% of acetabular fractures involving the posterior wall. Posterior dislocation at initial trauma was significantly lower in group I than in group II. There were no significant differences in the postoperative quality of reduction between the two groups. HO in five patients in each group, but there was no significant difference. There was no post-traumatic ONFH and conversion to THA in total population at a minimum 2-year follow up. There was no significant difference in term of HHS. It is important to carefully interpret the preoperative CT images to identify the marginal impaction and to achieve anatomical reduction and satisfactory surgical outcomes.