Damage control and austere environment external fixation: techniques for the civilian provider.

Extremity injuries associated with natural disasters and combat are typically high-energy, often open injuries, and routinely represent only part of the scope of injury to a poly-traumatized patient. The early management of these injuries is normally performed in austere environments, and relies heavily on the principles of damage control orthopaedics, with external fixation of associated long bone and peri-articular fractures. While the general principles of ATLS, wound management, and external fixation do not differ from that performed in the setting of civilian trauma, there are special considerations and alterations in standard practice that become necessary when providing this care in an austere environment. The purpose of this article is to review the principles and techniques of damage control orthopaedics and external fixation in the management of extremity trauma in the setting of combat- and natural disaster-related injuries.

Heterotopic ossification in complex orthopaedic combat wounds: quantification and characterization of osteogenic precursor cell activity in traumatized muscle.

BACKGROUND: Heterotopic ossification frequently develops following high-energy blast injuries sustained in modern warfare. We hypothesized that differences in the population of progenitor cells present in a wound would correlate with the subsequent formation of heterotopic ossification. METHODS: We obtained muscle biopsy specimens from military service members who had sustained high-energy wartime injuries and from patients undergoing harvest of a hamstring tendon autograft. Plastic-adherent cells were isolated in single-cell suspension and plated to assess the prevalence of colony-forming cells. Phenotypic characteristics were assessed with use of flow cytometry. Individual colony-forming units were counted after an incubation period of seven to ten days, and replicate cultures were incubated in lineage-specific induction media. Immunohistochemical staining was then performed to determine the percentage of colonies that had differentiated along an osteogenic lineage. Quantitative real-time reverse-transcription polymerase chain reaction was used to identify changes in osteogenic gene expression. RESULTS: Injured patients had significantly higher numbers of muscle-derived connective-tissue progenitor cells per gram of tissue (p < 0.0001; 95% confidence interval [CI], 129,930 to 253,333), and those who developed heterotopic ossification had higher numbers of assayable osteogenic colonies (p < 0.016; 95% CI, 12,249 to 106,065). In the injured group, quantitative real-time reverse-transcription polymerase chain reaction performed on the in vitro expanded progeny of connective-tissue progenitors demonstrated upregulation of COL10A1, COL4A3, COMP, FGFR2, FLT1, IGF2, ITGAM, MMP9, PHEX, SCARB1, SOX9, and VEGFA in the patients with heterotopic ossification as compared with those without heterotopic ossification. CONCLUSIONS: Our study suggests that the number of connective-tissue progenitor cells is increased in traumatized tissue. Furthermore, wounds in which heterotopic ossification eventually forms have a higher percentage of connective-tissue progenitor cells committed to osteogenic differentiation than do wounds in which heterotopic ossification does not form. The early identification of heterotopic ossification-precursor cells and target genes in severe wounds not only may be an effective prognostic tool with which to assess whether heterotopic ossification will develop in a wound, but may also guide the future development of individualized prophylactic measures.