Severe post-traumatic and post-arthroplasty acetabular defects: beyond Existing classifications

Background: Acetabular bone defects resulting from post-traumatic malunion or nonunion present distinct morphological challenges compared to those caused by chronic aseptic loosening in revision hip arthroplasty. Chronic pelvic discontinuity, characterized by the complete dissociation of the superior and inferior hemipelvis through the acetabular columns, represents a complex clinical entity with increasing incidence due to the rising volume of primary and multi-revision total hip arthroplasties.

Objective: This article evaluates current classification systems, diagnostic modalities, and surgical management strategies for severe acetabular defects and chronic pelvic discontinuity.

Key Points: While the Paprosky system is widely utilized, it often fails to adequately describe post-traumatic defects, necessitating newer frameworks like the Sen classification. Diagnosis requires ruling out infection and utilizing advanced imaging, specifically thin-slice helical CT with metal artifact reduction, to assess bone stock and column integrity. Surgical objectives include anatomical restoration of the center of rotation and acetabular offset. Reconstructive options range from traditional cages and structural allografts—which demonstrate high long-term failure rates—to contemporary techniques such as acetabular distraction, highly porous tantalum components with modular augments, and cup-cage constructs. For unclassifiable or extreme defects, custom-made 3D-printed titanium triflange implants offer a salvage solution, though they are constrained by high costs and production lead times.

Conclusion: Management of severe acetabular deficiency and pelvic discontinuity remains technically demanding. Although modern porous implants and patient-specific reconstructions show promising early-to-mid-term stability, clinical outcomes are frequently complicated by high rates of infection, dislocation, and mechanical failure.