Prolonged superficial local cryotherapy attenuates microcirculatory impairment, regional inflammation, and muscle necrosis after closed soft tissue injury in rats.
BACKGROUND
Closed soft tissue injury induces progressive microvascular dysfunction and regional inflammation. The authors tested the hypothesis that adverse trauma-induced effects can be reduced by local cooling. While superficial cooling reduces swelling, pain, and cellular oxygen demand, the effects of cryotherapy on posttraumatic microcirculation are incompletely understood.


METHODS
Controlled laboratory study.


METHODS
After a standardized closed soft tissue injury to the left tibial compartment, male rats were randomly subjected to percutaneous perfusion for 6 hours with 0.9% NaCL (controls; room temperature) or cold NaCL (cryotherapy; 8 degrees C) (n = 7 per group). Uninjured rats served as shams (n = 7). Microcirculatory changes and leukocyte adherence were determined by intravital microscopy. Intramuscular pressure was measured, and invasion of granulocytes and macrophages was assessed by immunohistochemistry. Edema and tissue damage was quantified by gravimetry and decreased desmin staining.


RESULTS
Closed soft tissue injury significantly decreased functional capillary density (240 +/- 12 cm(-1)); increased microvascular permeability (0.75 +/- 0.03), endothelial leukocyte adherence (995 +/- 77/cm(2)), granulocyte (182.0 +/- 25.5/mm(2)) and macrophage infiltration, edema formation, and myonecrosis (ratio: 2.95 +/- 0.45) within the left extensor digitorum longus muscle. Cryotherapy for 6 hours significantly restored diminished functional capillary density (393 +/- 35), markedly decreased elevated intramuscular pressure, reduced the number of adhering (462 +/- 188/cm(2)) and invading granulocytes (119 +/- 28), and attenuated tissue damage (ratio: 1.7 +/- 0.17).


CONCLUSIONS
The hypothesis that prolonged cooling reduces posttraumatic microvascular dysfunction, inflammation, and structural impairment was confirmed.


CONCLUSIONS
These results may have therapeutic implications as cryotherapy after closed soft tissue injury is a valuable therapeutic approach to improve nutritive perfusion and attenuate leukocyte-mediated tissue destruction. The risk for evolving compartment syndrome may be reduced, thereby preventing further irreversible aggravation.
Schaser
Klaus-Dieter
KD
Center of Musculoskeletal Surgery, Charité-University Medicine Berlin, Germany. klaus-dieter.schaser@charite.de
Disch
Alexander C
AC
Stover
John F
JF
Lauffer
Annette
A
Bail
Herman J
HJ
Mittlmeier
Thomas
T
D000704:Analysis of Variance; D000818:Animals; D017679:Cryotherapy / Q000379:methods; D007249:Inflammation / Q000517:prevention & control; D007962:Leukocytes / Q000502:physiology; D016014:Linear Models; D008264:Macrophages / Q000502:physiology; D008297:Male; D008833:Microcirculation / Q000503:physiopathology*; D008856:Microscopy, Fluorescence; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000293:injuries / Q000503:physiopathology; D009336:Necrosis / Q000517:prevention & control; D020556:Neutrophil Infiltration; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017695:Soft Tissue Injuries / Q000503:physiopathology / Q000628:therapy*