Pseudo-Protrusio Acetabular Deformity in Osteogenesis Imperfecta Patients

Area of Science:

• Orthopedics
• Radiology
• Genetics

Background:

• Osteogenesis imperfecta (OI) is a genetic disorder characterized by brittle bones.
• OI can lead to various skeletal deformities, including acetabular abnormalities.
• A pseudo-protrusio-type acetabular deformity (PPAD) has been observed in OI patients.

Purpose of the Study:

• To determine the incidence and patterns of acetabular deformity in Osteogenesis Imperfecta (OI) patients using 3D-CT and radiographs.
• To identify radiographic signs associated with PPAD in OI.
• To correlate acetabular deformity with disease severity in OI.

Main Methods:

• Systematic review of 3D-CT scans and pelvis radiographs from 295 OI patients (590 hips).
• Analysis of acetabular morphology and identification of PPAD using 3D-CT.
• Evaluation of radiographic signs, including ilioischial line, iliopectineal line, and acetabular line contours on plain radiographs.

Main Results:

• 21% of OI hips (123/590) exhibited deformed acetabula, significantly associated with disease severity.
• 17 hips showed PPAD, characterized by crumpled hemipelvis, upwardly rotated acetabular roof, and superior hip center migration.
• Superomedial bulging of the iliopectineal line was the most predictive sign for PPAD (73% sensitivity, 100% specificity).

Conclusions:

• Acetabular deformity, including PPAD, is prevalent in OI patients and linked to disease severity.
• PPAD in OI may lead to anterior uncovering of the hip joint without necessarily causing femoroacetabular impingement.
• Superomedial bulging of the iliopectineal line is a significant radiographic indicator for identifying PPAD in OI.