Does sequential examination under anaesthesia provide a reliable method to determine a management plan for unstable lateral compression pelvic ring injuries? a prospective study.

PURPOSE: To assess the reliability of sequential examination under anaesthesia (EUA) to determine pelvic instability and to evaluate radiological and functional outcomes in unstable lateral compression (LC) injuries. METHODS: A prospective case series study was conducted from 2020 to 2022 at a university hospital on 43 cases with LC injuries that met the inclusion criteria. Sequential EUA was carried out in three steps. Posterior-only fixation or anterior-posterior fixation was done according to the algorithm. Each patient was followed up for at least 12 months, both radiologically and functionally. RESULTS: Forty cases proved unstable and were fixed. None showed secondary displacement in the anterior-posterior fixation group. However, five cases (19.2%) of the posterior-only fixation group showed secondary displacement with a mean of 5.9 mm. Four cases of them had tetra-ramic injuries. There is a high tendency for secondary displacement at 14.5 mm or more preoperative displacement of the rami. Patients with secondary displacement showed comparable functional outcome scores to patients without secondary displacement. Posterior-only fixation showed shorter operative time, lesser radiological exposure, blood loss and iatrogenic nerve injury than anterior-posterior fixation. CONCLUSION: EUA is a reliable method to determine pelvic instability and management plan for LC fractures with unilateral anterior ring injury. Anterior-posterior fixation is needed if there is a tetra-ramic fracture or initial anterior ring displacement of 14.5 mm or more, irrespective of EUA.