Soft-tissue injuries involve muscles and the bands of connective tissue known as tendons and ligaments. Tendons connect muscle to bone, while ligaments connect bone and bone, providing joint stability.
A strain occurs when a muscle or tendon is torn or stretched. In severe cases, muscle fibers can tear, or the tendon can detach from the muscle or bony attachment.
A sprain is an injury to a ligament. Sprains usually occur when a joint is forced to move beyond its normal range of motion. Ligament sprains are graded according to the resultant joint instability. A grade 1 or “mild” sprain causes pain and tenderness along the ligament, but not increased joint instability. A grade 2 or “moderate” sprain results in a partial tear of a ligament, and a grade 3 or “severe” sprain is a complete tear or disruption of a ligament to the point where the ligament does not provide any stability to the joint.
A contusion is a muscle bruise usually brought on by a jarring blow, as when a defensive linesman rams helmet-first into an opposing running back’s thigh muscle (quadriceps) while making a tackle. Bleeding in this muscle may result in swelling, pain, spasm and restricted motion in the muscle. In some situations, a deep muscle contusion can result in the muscle becoming warm, tender and firm to the touch. This calcification of muscle contusion is known as myositis ossificans traumatica.