A New Computed Tomography-Based Measure that Provides Insight Into Hip Stability in Patients With Posterior Wall...

Area of Science:

• Orthopedic surgery
• Radiology
• Trauma care

Background:

• Posterior wall acetabular fractures (PWF) are complex injuries.
• Assessing stability is crucial for treatment decisions.
• Existing CT measures have limitations in predicting instability.

Purpose of the Study:

• To introduce and evaluate a novel sagittal plane computed tomography (CT)-based angular measurement for predicting stability in posterior wall acetabular fractures (PWF).
• To compare the diagnostic performance of this new measure against established axial CT criteria.

Main Methods:

• Retrospective review of 58 consecutive patients with PWF (AO/OTA class 62A.1) at an academic trauma center.
• A new sagittal CT angular measure was developed, assessing the angle subtended by the joint center, cranial, and caudal fracture exits.
• Comparison with examination under anesthesia (EUA) and prior axial CT measures (wall involvement >50%, cranial exit within 5mm of dome).

Main Results:

• The new sagittal CT angular measure demonstrated 100% sensitivity and 100% specificity in predicting hip stability (≤70 degrees) and instability (>70 degrees).
• In contrast, prior axial CT measures showed lower sensitivity and specificity for predicting instability.
• Specifically, ≥50% wall involvement had 67% sensitivity/60% specificity, and fracture within 5mm of the dome had 86% sensitivity/73% specificity.

Conclusions:

• The novel sagittal CT angular measurement is a highly accurate tool for predicting hip stability after posterior wall acetabular fractures.
• This method offers superior diagnostic performance compared to existing axial CT-based assessments.
• A threshold of ≤70 degrees reliably predicts stability, while >70 degrees predicts instability in PWF.