Acetabular cup version modelling and its clinical applying on plain radiograms.

Area of Science:

• Orthopedic Surgery
• Radiology
• Biomedical Engineering

Background:

• Acetabular cup malversion is a known risk factor for dislocation after total hip arthroplasty (THA).
• Accurate assessment of cup version is crucial for preventing complications such as dislocation and impingement.
• Current methods for assessing cup version may require advanced imaging or be time-consuming.

Purpose of the Study:

• To evaluate the sensitivity and specificity of a radiographic assessment of acetabular cup version using anteroposterior hip and pelvis views.
• To determine the incidence of inadequate cup version in patients experiencing recurrent dislocations post-THA.
• To assess the clinical utility of the sign of anteversion insufficiency (SAI) in identifying patients at risk.

Main Methods:

• Retrospective radiographic analysis of 2 groups of patients undergoing primary THA.
• Group 1: 32 patients with early revision for dislocation.
• Group 2: 164 patients without dislocations; analysis of cup anteversion using anteroposterior views and cross-tabulation (2x2).

Main Results:

• The sign of anteversion insufficiency (SAI) demonstrated a specificity of 92% (95% CI: 88%-96%) and a sensitivity of 29% (95% CI: 9%-46%).
• Patients with SAI had a 3.4 times higher relative risk of dislocation (95% CI: 1.8-6.3).
• Statistical significance was noted with χ² Yates = 10.668 (P < 0.01).

Conclusions:

• The anteroposterior radiographic assessment provides a reliable and simple qualitative evaluation of acetabular component version.
• SAI can be a valuable tool for identifying patients with potential implant issues, including loosening, dislocations, and impingement.
• This method aids in planning revision surgery, though computed tomography (CT) remains essential for definitive cup position assessment.