Unusual Pattern of Osteochondral Marginal Impaction in Acetabular Fractures: A Report of Two Cases.

Acetabular fractures could be accompanied by articular impaction injuries, affecting the outcomes if missed or treated less than optimally. Marginal impaction detected either in preoperative or intraoperatively imaging studies should be anatomically reduced using the femoral head as a template and augmenting the defect with bone graft if needed. The impacted segment articular surface looks enface during surgery, which is the classic description of such injuries. In the present report, we describe an unusual pattern of marginal impaction injuries appearance in two patients, in which the impacted fragment articular surface is facing toward the joint cavity, which is the reverse of the classic description, alluding to the probable mechanism of its occurrence, the technique for reduction, and the consequences of missing such injuries. Marginal impaction injuries should be diagnosed and treated correctly to preserve joint congruency; however, the surgeon should be aware of the possibility of an unusual pattern of marginal impaction in which the fragment could be reversed, and keeping this possibility in mind would make its diagnosis and management easier.