Radiological comparison of acetabular anteversion on roentgenograms and computed tomograms functional outcomes in total hip arthroplasty

Abstract

Introduction: Orientation and Alignment of prosthetic components are vitally important for the stability of total hip arthroplasty. Poor acetabular positioning is one of the many issues implicated with persistent pain due to impingement, dislocation, edge loading and liner fracture, which may be lead to patient dissatisfaction after total hip arthroplasty. Material and methods: Post-operative radiological analysis of the version of acetabulum through X-ray images and CT images was performed. Pre & post-operative scoring according to Modified Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Hip Score (OHS) was documented. Results: A total of 55 patients were included in the study. The mean anteversion angle calculated on anteroposterior (AP) radiographs by Lewinnek’s method was 23.480 (Range 11 – 390) and on cross-table lateral radiograph by Woo and Morrey's method was 22.410 (Range16 – 560), compared to CT Scans measured was 28.640 (Range 11.10 – 50.100). Conclusion: Majority 69.09% of patients had excellent functional outcomes in a range of 11.1 – 360 of anteversion compared to Lewinnek’s safe zone. It suggests that there is flexibility in positioning the acetabular component than previously believed. If one has to err, it should be towards more anteversion. Infact to avoid dislocation, more anteversion is required to guard against unwarranted activities on part of the patient.