Characterizing acetabular defects and need of major reconstruction during total hip arthroplasty in patients with acetabular protrusion- a retrospective study.

Purpose: Total hip arthroplasty (THA) in patients with acetabular protrusion can be challenging due to the lack of acetabular bone support. Some patients may require a major reconstructive procedure to aid in the fixation of the acetabular components. The purpose of the study was to characterize the type of acetabular defects in patients with protrusion and to assess the need for major reconstruction. Methods: This was a retrospective study of 125 THAs performed at a single tertiary center from 2010 to 2020 by a single surgeon in patients with acetabular protrusion. Demographics, operative details and radiographic details were recorded. THAs in which a structural graft, cage or augment were used for acetabular reconstruction were considered to have undergone a major reconstructive procedure and a classification system was proposed to identify patients requiring major reconstruction. Results: 10 (8 %) THAs required a major reconstruction in our cohort (2- augment, 8- structural allograft. There was significant difference in acetabular defects based on the etiology. Major reconstruction was more common when the diagnosis was sequalae of tuberculosis or post-traumatic arthritis. Simple cavitatory defects seldom required a major reconstruction while combined defects and medial wall deficiency increased the risk of requiring a major reconstruction. Conclusion: The severity of defects varied considerably with majority of patients having cavitatory type of defect which can be successfully managed without the need of any major reconstructive measures. A simple classification based on the type of defect and medial wall competency appeared to be useful in identifying patients who may need a major reconstructive procedure during THA.