RESUMO
INTRODUCTION: Previously, 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 METHODS: Male 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. RESULTS: All 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. CONCLUSIONS: An increasing injury burden causes a decreasing blood supply capacity and revascularization, and leads to impaired callus formation and an increasing delay in bone healing.
Assuntos
Lesões dos Tecidos Moles/fisiopatologia , Traumatismos Torácicos/fisiopatologia , Fraturas da Tíbia/fisiopatologia , Ferimentos não Penetrantes/fisiopatologia , Animais , Velocidade do Fluxo Sanguíneo , Calo Ósseo/fisiopatologia , Modelos Animais de Doenças , Consolidação da Fratura , Fluxometria por Laser-Doppler , Masculino , Ratos , Ratos Wistar , Lesões dos Tecidos Moles/complicações , Traumatismos Torácicos/complicações , Fraturas da Tíbia/complicações , Ferimentos não Penetrantes/complicaçõesRESUMO
BACKGROUND AND PURPOSE: There is some clinical evidence that fracture healing is impaired in multiply injured patients. Nothing is known, however, about the effects of various types of injuries and their contribution to a possible disturbance of the fracture-healing process. We investigated the effect of a thoracic trauma and an additional soft-tissue trauma on fracture healing in a rat tibia model. METHODS: 3 groups of rats were operated: group A with a simple fracture of the tibia and fibula, group B with a fracture and an additional thoracic trauma, and group C with a fracture, thoracic trauma, and an additional soft-tissue trauma. The fracture and the soft-tissue injury were produced by a special guillotine-like device and the thoracic trauma by a blast wave generator. After one day, the serum level of IL-6 was quantified, and at the end of the study (28 days) the mechanical properties and the callus volume of the healed tibia were determined. RESULTS: Increasing the severity of the injury caused IL-6 levels to more than double 1 day after injury. It halved the load to failure in mechanical tests and led to reduced callus volume after 28 days of healing. INTERPRETATION: Fracture healing is impaired when additional thoracic trauma and soft tissue trauma occurs.
