Immediate microcirculatory derangements in skeletal muscle and periosteum after closed tibial fracture.
BACKGROUND
Severe musculoskeletal soft tissue injury sustained after a closed fracture to the extremities significantly influences bone healing and determines the patient's prognosis. The present study was aimed at quantitatively assessing immediate microcirculatory changes in skeletal muscle and periosteum after standardized closed fracture.


METHODS
Standardized closed fracture of the left tibia in isoflurane-anesthetized Sprague-Dawley rats (n = 14) was induced using a modified weight-drop technique. The left extensor digitorum longus (EDL) muscle (n = 7) and tibial periosteum (n = 7) were surgically exposed for in vivo fluorescence microscopy 15 minutes after fracture. Nonfractured rats (n = 14) served as controls. EDL muscle edema was determined by the ratio of wet to dry weight (EDL water content).


RESULTS
Closed tibial fracture resulted in a significant reduction of functional capillary density, red blood cell velocity, and volumetric blood flow in both EDL muscle and periosteum. Microvascular diameter, leukocyte adherence, and macromolecular leakage were markedly increased, indicating trauma-induced inflammation and endothelial disintegration. EDL muscle edema was found increased significantly after fracture.


CONCLUSIONS
This model permits for the first time direct in vivo visualization and quantification of fracture-induced microhemodynamic changes and cellular interactions within the surrounding soft tissue. It demonstrates that even simple fractures lead to profound microcirculatory disturbances in skeletal muscle and periosteum, and also at sites remote from the diaphyseal fracture site. It provides a useful approach for the development of therapeutic strategies to counteract fracture-induced microvascular dysfunction.
Zhang
Li
L
Department of Trauma and Reconstructive Surgery, Charité Campus Virchow, Humboldt-University, Berlin, Germany.
Bail
Hermann
H
Mittlmeier
Thomas
T
Haas
Norbert P
NP
Schaser
Klaus-D
KD
D000818:Animals; D002199:Capillary Permeability; D004487:Edema / Q000209:etiology; D005596:Fractures, Closed / Q000503:physiopathology*; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply*; D009135:Muscular Diseases / Q000209:etiology; D010521:Periosteum / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000098:blood supply; D013978:Tibial Fractures / Q000150:complications / Q000503:physiopathology*