vendex and Hematoma

The purpose of this study was to determine whether both neutrophils and macrophages infiltrate the hematoma site of stretch-injured rabbit tibialis anterior muscle. The Mab.198 antibody was used to detect CD11b(+) neutrophils or macrophages. Neutrophils were identified specifically by using the RPN3/57 antibody. The RAM11 antibody was used to detect macrophages. The histological characteristics of the hematoma site, torn fibers or inflammatory cells, were present primarily at 4 and 24 h, but not at 48 and 72 h after injury. A difference in the Mab.198(+) cellular concentration was detected over time between uninjured and injured muscles (P = 0.03). The injured-uninjured difference in the RPN3/57(+) or RAM11(+) cellular concentrations approached significance (P = 0.07) or else was deemed insignificant (P = 0.13), respectively. Therefore, neutrophils may predominate over RAM11(+) macrophages in stretch-injured muscle. These findings may influence the antiinflammatory strategies used to treat stretch injuries.

Topics: Animals; Antigens, Differentiation; Biomarkers; Cell Count; Disease Models, Animal; Disease Progression; Hematoma; Immunohistochemistry; Macrophage-1 Antigen; Macrophages; Muscle, Skeletal; Neutrophil Infiltration; Neutrophils; Rabbits; Sprains and Strains; Stress, Mechanical; Torque

Herein we describe a new test system to produce a standardized partial muscle-tendon junction (MTJ) stretch injury. In anesthetized rabbits the tibialis anterior (TA) muscle-tendon unit is unilaterally shortened using a custom designed clamp roller system. An angular displacement (average velocity of 450 degrees x s[-1]) is applied about the foot to plantarflex the ankle 90 degrees while the lower extremity is fixed. During ankle rotation the TA muscle is tetanically stimulated to generate an eccentric stretch injury at the MTJ. Forty-eight hours after injury, isometric torque deficit (injured/sham) was measured. Two groups of animals (N = 6 in each group) were tested with the only difference between the two groups being the initial tendon shortening. In Group 1 (tendon shortening = 1.2 cm. N = 6) the torque deficit was 36.7+/-5.9% (mean+/-SD). In Group 2 (tendon shortening = 1.5 cm. N = 6) the torque deficit was 58.7+/-7.4% (mean+/-SD). No order effect was suggested by the data (P = 0.6062), but the difference in torque deficit between the two groups was highly significant (P = 0.0001). For all tests in which the tendon was temporarily shortened before muscle stimulation and stretch (N = 12) there was a visible hematoma at the MTJ similar to the injury that is common in athletic injuries. Histological evaluation 48 h after injury revealed both fiber tearing and inflammation at the MTJ. In addition, there was focal fiber damage in the muscle belly for both groups. The damage and inflammatory process, however, were more severe in the group with greater initial tendon shortening.

Topics: Analysis of Variance; Animals; Equipment Design; Hematoma; Hemorrhage; Models, Biological; Muscle, Skeletal; Rabbits; Rotation; Tendon Injuries; Torque