Development of a Radiographic Scoring System to Estimate Acetabular Protrusion Risk in Patients with Osteolytic...

Area of Science:

• Orthopedic oncology
• Radiology
• Biomechanical engineering

Background:

• Periacetabular metastases can lead to protrusio acetabuli, a debilitating condition requiring surgery.
• Identifying structural changes predicting protrusio acetabuli is crucial for risk stratification.

Purpose of the Study:

• To identify specific structural changes associated with progression to protrusio acetabuli.
• To develop a scoring system for risk stratification of patients with periacetabular metastases.

Main Methods:

• Retrospective cohort study of 87 patients with periacetabular metastases.
• Analysis of CT scans to evaluate bone destruction and cortical bone mass.
• Development of a radiographic risk scoring system and receiver operating characteristic (ROC) curve analysis.
• Finite element analysis for biomechanical validation.

Main Results:

• Bone defects, thinning, or fractures in the middle-third (apex) of the acetabular dome, with contiguous involvement, predicted protrusio.
• A >50% decrease in acetabular dome cortical bone mass was associated with protrusio.
• The developed scoring system demonstrated 95.0% sensitivity and 91.0% specificity for protrusio progression with a score of ≥3.0.
• Cortical bone loss in the middle-third (apex) was biomechanically critical.

Conclusions:

• Clinical and radiographic predictors can stratify periacetabular metastasis patients by protrusio risk.
• Surgical stabilization of the acetabular dome's middle-third (apex) is key to preventing or delaying protrusio acetabuli.