Utility of Radiographs, Computed Tomography, and Three Dimensional Computed Tomography Pelvis Reconstruction for Identification of Acetabular Defects in Residency Training

PURPOSE: The Paprosky classification system of acetabular defects is complex and its reliability has been questioned. The purpose of this study was to evaluate the effectiveness of different radiologic imaging modalities in classifying acetabular defects in revision total hip arthroplasty (THA) and their value of at different levels of training. MATERIALS AND METHODS: Bone defects in 8 revision THAs were classified by 2 fellowship-trained adult reconstruction surgeons. A timed presentation with representative images for each case (X-ray, two-dimensional computed tomography [CT] and three-dimensional [3D] reconstructions) was shown to 35 residents from the first postgraduate year of training year of training (PGY-1 to PGY-5), 2 adult reconstruction fellows and 2 attending orthopaedic surgeons. The Paprosky classification of bone defects was recorded. The influence of image modality and level of training on classification were analyzed using chi-square analysis (alpha=0.05). RESULTS: Overall correct classification was 30%. The level of training had no influence on correct classification (P=0.531). Using X-ray led to 37% correctly identified defects, CT scans to 33% and 3D reconstructions to 20% of correct answers (P<0.001). There was no difference in correct classification based defect type (P<0.001). Regardless of level of training or imaging, 64% of observers recognized type 1 defects, compared to only 16% correct recognition of type 3B defects. CONCLUSION: Using plain X-rays led to an increased number of correct classification, while regular CT scan and 3D CT reconstructions did not improve accuracy. The classification system of acetabular defects can be used for treatment decisions; however, advanced imaging may not improve its utilization.