Long-term myoneural function after an induced compartment syndrome in the canine hindlimb.

For evaluation of long-term myoneural function in a compartment syndrome model of the canine hindlimb, five conditioned dogs had injections of autologous plasma into the hindlimb anterolateral muscle compartment, maintaining the pressure at 40 mmHg for eight hours. A newly described technique for measuring muscle function was used before pressurization and at weekly intervals following pressurization for a period of one month. Two days after pressurization, isometric twitch torque and tetanic torque showed a significant decrease (p less than .05) when compared with baseline values. Time to peak tension, one-half relaxation time, and endurance tests showed no significant change throughout the four-week testing. At four weeks following pressurization, no muscle dysfunction was noted, and muscle examined histologically was normal. Therefore, the initial muscle dysfunction present was reversed by skeletal muscle recovery or regeneration. Although no long-term muscle dysfunction occurred in this study of dogs, there may exist a lower tolerance to elevated intramuscular pressure in humans. Since dogs have only fatigue-resistant muscle fibers with higher oxidative capacity than human fibers, dog muscle may have a greater regenerative capacity than human muscle. Therefore, exact extrapolation of these dog studies to clinical compartment syndromes is difficult. Although muscle function was recovered in these animal experiments, human muscle may have less capacity to recover. It is advisable to decompress muscle compartments at a pressure of 30 mmHg as soon as clinical symptoms of a compartment syndrome appear.