Muscle damage can be direct or indirect. Direct damage can be the result of a contusion or laceration. Indirect damage can be the result of strains of varying degrees of severity. The lightest injury, grade I, is caused by a contusion or tear of a few fibers of the muscle. In this case there will be minimal loss of function, slight swelling and pain, sensation of muscle stiffness above and below the lesion. When the muscle is relaxed at the moment it receives direct blunt trauma, the damage occurs deep in the muscle, the tissue being crushed between the force applied from the outside (for example a knee) and the bone. If the muscle, however, is contracted when hit, the damage is more superficial because the muscle tension absorbs and attenuates some of the external forces. Moderate, or grade II, damage involves more tissue involvement and more loss of function. When the tear occurs throughout the entire muscle, it is called grade III, or severe, and is associated with a total loss of function. Finally, grade IV occurs when the muscle rupture occurs. The overflow of blood from the broken capillaries will fill the surrounding area. Where the fascia, which covers the muscle, remains intact, the hematoma formed will be contained (intramuscular hematoma). Where, however, there has also been a rupture of the fascia (intermuscular hematoma), the blood will flow out of the laceration and the fascial pressure, absent in this case, will not limit the bleeding. The blood loss will be greater and the extravasation will move between the fascia of two neighboring muscles in the interfascial space to emerge further downstream (and this is the reason why the tear is often higher up than where the hematoma is seen), or it will move into the interstitial space to be reabsorbed.
Comments