A novel acetabular injury pattern: Posterior osteochondral impaction without cortical involvement

Acetabular fractures typically involve disruption of cortical columns or walls and are well-classified by Judet, Letournel, and AO/OTA systems. However, some injuries involve pure osteochondral impaction of the articular surface without cortical involvement, making them difficult to detect and unclassified by current systems. This study identifies and evaluates a rare, previously undescribed acetabular injury pattern-posterior dome osteochondral impaction without cortical fracture.

To characterize this unique injury pattern and assess clinical and radiological outcomes following two surgical techniques aimed at anatomical restoration.

A retrospective review was conducted on eight patients (six males, two females; mean age 34 years) treated at a tertiary referral center between 2008 and 2023. Inclusion criteria included isolated posterior dome osteochondral impaction confirmed by computed tomography, absence of cortical disruption, and minimum six months follow-up. Patients underwent surgical management via either posterior wall osteotomy or a cortical window technique, with subchondral support provided by autologous bone graft or rafting screws. Functional outcomes were measured using the Modified Merle d'Aubigné and Postel score. Radiological results were assessed according to Matta criteria.

All injuries followed high-energy trauma, predominantly motor vehicle collisions. Posterior wall osteotomy was performed in five patients: cortical window technique in three. Anatomical reduction was achieved and confirmed radiologically in all cases. At a mean follow-up of 12 months, no evidence of secondary collapse, hardware failure, or early osteoarthritis was noted. Functional outcomes were excellent in five patients and good in three (mean Merle d'Aubigné score 16.4).

Isolated osteochondral impaction of the posterior acetabular dome without cortical fracture is a distinct injury not encompassed by current classification systems. Surgical intervention using posterior wall osteotomy or cortical window elevation facilitates anatomical reduction and yields excellent mid-term outcomes. Recognition of this lesion and its inclusion in future acetabular fracture classifications are essential for accurate diagnosis and optimal treatment.