• Lutz Claes, Florian Gebhard, Anita Ignatius, Raimund Lechner, Stefan Baumgärtel, Michael Kraus, and Gert D Krischak.
• Centre of Musculoskeletal Research, Institute of Orthopaedic Research and Biomechanics, Ulm University, Helmholtzstrasse 14, 89081, Ulm, Germany. lutz.claes@uni-ulm.de.
• Arch Orthop Trauma Surg. 2017 Jul 1; 137 (7): 945-952.

IntroductionPreviously, it was found that fracture healing is impaired by blunt chest trauma and an additional soft-tissue trauma. The mechanisms leading to this disturbance are largely unknown. Here, we investigated the effect of thoracic and soft-tissue trauma on blood flow of the injured lower leg and on tissue differentiation and callus formation during fracture healing.Materials And MethodsMale Wistar rats received either a mid-shaft fracture of the tibia alone (group A), an additional chest trauma (group B), or additional chest and soft-tissue traumas (group C). Peripheral blood flow was determined by Laser Doppler Flowmetry before and after the injury, and on observation days 1, 3, 7, 14, and 28. Quantitative histological analysis was performed to assess callus size and composition.ResultsAll groups displayed an initial decrease in blood flow during the first 3 days post-trauma. A recovery of the blood flow that even exceeded preoperative levels occurred in group A and later and to a lesser degree in group B, but not in group C. The amount of callus formation decreased with increasing trauma load. More cartilage was formed after 7 days in groups B and C than in group A. At later healing time points, callus composition did not differ significantly.ConclusionsAn increasing injury burden causes a decreasing blood supply capacity and revascularization, and leads to impaired callus formation and an increasing delay in bone healing.

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