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Direct Mouse Trauma/Burn Model of Heterotopic Ossification
Published on: August 6, 2015
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Bioburden Increases Heterotopic Ossification Formation in an Established Rat Model
Gabriel J Pavey1, Ammar T Qureshi, Donald N Hope
1Regenerative Medicine Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA.
Clinical Orthopaedics and Related Research
|March 31, 2015
Summary
Early bacterial contamination, particularly methicillin-resistant Staphylococcus aureus (MRSA), significantly increases heterotopic ossification (HO) after combat-related amputations. Mitigating wound contamination and inflammation is crucial for reducing ectopic bone formation.
Area of Science:
- Trauma and regenerative medicine
- Surgical innovation
- Infectious disease research
Background:
- Heterotopic ossification (HO) is common in combat amputations, with early bacterial colonization a suspected risk factor.
- A novel small animal model of trauma-induced HO, mimicking combat injuries without initial bacterial contamination, was previously established.
- This study investigates the role of bacterial bioburden in exacerbating HO.
Purpose of the Study:
- To determine if bacterial presence (Acinetobacter baumannii and MRSA) amplifies ectopic bone formation in traumatized muscle post-amputation.
- To assess the long-term effects of bacterial contamination on microbial flora at the amputation site.
Main Methods:
- A blast-related HO rat model was used, involving blast overpressure, femur fracture, crush injury, and amputation.
- Rats were inoculated with A. baumannii or MRSA, or a vehicle control.
- Ectopic bone formation was quantified using micro-CT and histomorphometry at 12 weeks.
Main Results:
- MRSA infection led to significantly greater HO volume (68.9 mm³) compared to A. baumannii (20.9 mm³) or vehicle (16.3 mm³).
- While A. baumannii was cleared, other bacteria persisted in tissues; MRSA persisted in tissues at 12 weeks.
- Increased HO in MRSA-infected rats suggests a link between persistent infection, inflammation, and ectopic bone growth.
Conclusions:
- Persistent MRSA infection significantly increases ectopic bone formation in a trauma-induced HO model.
- Early wound colonization by bacteria, especially MRSA, is a key risk factor for severe HO.
- Interventions targeting wound contamination and inflammation may reduce HO and warrant further preclinical investigation.
