High- vs. low-energy acetabular fractures: a propensity-matched analysis of outcomes and complications in four hundred and sixty four patients.

backgroundAcetabular fractures occur across a wide age spectrum with a reported incidence of three to 11 per 100,000 person-years, and result from both high-energy and low-energy trauma mechanisms. Low-energy acetabular fractures typically occur in older patients, while high-energy acetabular fractures occur in much younger patients. This study aimed to compare the outcomes of operatively treated acetabular fractures by trauma mechanism before and after matching to account for differences in patient characteristics.

methodsA retrospective cohort study was conducted on 464 patients who underwent surgical fixation of acetabular fractures with a minimum follow-up of three months. Patients were classified as low-energy or high-energy based on trauma mechanism. Propensity score matching was performed using age, preoperative haemoglobin, and smoking status.

resultsBefore matching (104 low-energy vs 360 high-energy patients), low-energy patients were older, had higher preoperative haemoglobin, and lower smoking rates. Operative time was significantly shorter in the low-energy group, and postoperative residual step-off was greater. Fracture pattern differed significantly between groups (p = 0.001), with anterior predominant fractures more frequent in the low-energy group. Posterior wall involvement was more common in high-energy fractures. Surgical approach differed significantly (p < .001), with the anterior approach used more frequently in the low-energy group and combined approaches almost exclusively in the high-energy group. Associated lesions and loose bodies were more prevalent in high-energy fractures. Post-traumatic osteoarthritis was more frequent in the low-energy group and heterotopic ossification was more frequent in the high-energy group. After 1:1 propensity score matching, most baseline, fracture-pattern, surgical-approach, and radiographic differences were no longer significant. Four differences persisted: heterotopic ossification was more frequent in the high-energy group (7.2% vs 1.1%, p = 0.040) along with associated lesions (38.3% vs 10.6%, p < .001), loose bodies (33.7% vs 20.7%, p = 0.047), and greater intraoperative blood loss (delta Hb: -2.10 ± 1.25 vs -1.70 ± 0.99 g/dl, p = 0.019).

conclusionAfter controlling for patient-related factors, heterotopic ossification remained significantly associated with high-energy trauma after matching. Greater intraoperative blood loss in the high-energy group persisted after matching. These findings suggest that patient characteristics rather than trauma energy are the primary determinants of most postoperative outcomes.