Objectives: Occult instability in minimally displaced lateral compression (LC) pelvic ring injuries may have clinical relevance for treatment. We describe two novel LC pelvis fracture stress examinations - pelvic binder stress radiography (PBR) and pelvic binder stress bladder manometry (PBM) - which do not require sedation, anesthesia, patient transport, or radiation of personnel.
Methods: A biomechanical study was performed with five fresh elderly cadavers. Sequential osteotomies of the pelvis simulated increasingly unstable LC pelvis fracture patterns (OTA/AO 61A2.2, 61B1.1a, 61B1.1b, 61B2.1). Compressive force was quantitatively applied using a pelvic binder and scale. Pelvis fracture displacement was measured on AP and inlet fluoroscopic views. Pelvic bladder pressure (PBM) was measured using a Foley catheter as a water column.
Results: Fracture displacement strongly correlated with force applied (R2=0.600-0.963). PBR discriminated between simulated LC injuries. Mean displacement of 61B1.1b injuries >1cm was observed at 3.8kg on AP view and 5kg on inlet view. Mean displacement of 61B1.1a injuries >1cm was observed at 8.2kg on AP view and 9.3kg on inlet view. 61A2.2 injuries did not displace >1cm at forces up to 10kg. >95% of 61B1.1a and 61B1.1b injuries displaced >1cm at 10kg. PBM moderately correlated with force applied (R2=0.517-0.842) but did not discriminate between LC injuries.
Conclusions: PBR is feasible, precisely quantified occult mechanical instability in simulated LC pelvis fractures in response to reproducible applied force, and discriminated between simulated LC pelvis fractures. PBM did not discriminate between simulated LC fractures. A clinical trial to validate the safety and efficacy of PBR for assessing occult instability in LC pelvis fracture is warranted.
Keywords: Cadaver; Fracture; LC1; Lateral compression; Occult instability; Pelvis; Radiography; Stress.
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