A soft tissue injury (STI) is the damage of muscles, ligaments and tendons throughout the body. Common soft tissue injuries usually occur from a sprain, strain, a one off blow resulting in a contusion or overuse of a particular part of the body. Soft tissue injuries can result in pain, swelling, bruising and loss of function. A soft tissue injury (STI) is the damage of muscles, ligaments and tendons throughout the body. Common soft tissue injuries usually occur from a sprain, strain, a one off blow resulting in a contusion or overuse of a particular part of the body. Soft tissue injuries can result in pain, swelling, bruising and loss of function. A sprain is a type of acute injury which results from the stretching or tearing of a ligament. Depending on the severity of the sprain, the movement on the joint can be compromised since ligaments aid in the stability and support of joints. Sprains are commonly seen in vulnerable areas such as the wrists, knees and ankles. They can occur from movements such as falling on an outstretched hand or a twisting of the ankle or foot.