Standardization and Reproducibility of Dynamic Stress Testing for Occult Pelvic Ring Instability

Area of Science:

• Orthopaedic Surgery
• Trauma Care
• Biomechanics

Background:

• Pelvic ring injuries require assessment for occult instability to prevent displacement and morbidity.
• Current examination under anesthesia (EUA) protocols lack standardized force application.
• Variability in applied force during EUA may impact diagnostic accuracy.

Purpose of the Study:

• To quantify the forces utilized by experienced orthopaedic trauma surgeons during pelvic EUA.
• To identify variability in force application during standardized EUA maneuvers.

Main Methods:

• Simulated EUA maneuvers (internal rotation, external rotation, push-pull) were performed on cadavers by 18 orthopaedic traumatologists.
• Forces were measured using handheld dynamometers during simulated examinations.
• Surgeons' experience levels ranged from less than 5 years to over 20 years.

Main Results:

• A wide range of forces were applied: 40.4–374.9 N (IR), 72.9–338.4 N (ER), and 25–323 N (push-pull).
• Significant inter-surgeon variability in applied force was observed.
• Intra-surgeon variability exceeding 50 N was noted in 18% of serial trials for internal rotation.

Conclusions:

• This study is the first to measure forces during pelvic EUA for stability assessment.
• Considerable variability exists among surgeons and even within serial examinations by the same surgeon.
• Further research is necessary to standardize EUA displacement measurements and instability thresholds for clinical management.