Tendinitis (also spelled tendonitis) is one of the most common and debilitating of musculoskeletal injuries, in both the athletic world and among the general population. Given the structure of the human body—where tendons are engaged in the execution of virtually every type of muscular action—tendons are subjected to ongoing physical stress rendering them vulnerable to injury.
Tendons are the strong, fibrous, connective tissues that are the linkage between skeletal muscle and the bones that are powered by muscular contraction. Tendons are primarily constructed with collagen, which comprise 85% of the mass of the tendon. Collagen is a form of protein that provides the tendon with its elasticity in movement. Most tendons are constructed so that the structure glides over the adjacent bone, synchronized with the extensions and contractions of the powering muscle.
Tendinitis is an inflammation of the fibers that form the tendon, resulting in pain in varying degrees, and often some restriction of movement, usually most noticeable during and immediately after the activity. Tendinitis is a condition that may be caused through a number of mechanisms, including overuse of the of the tendon, commonly the result of a repetitive motion; an absence of "glide" between the tendon and the bone; and inflexibility in either the tendon or the connected muscle. In older athletes, collagen tends to lose some of its elasticity, causing the tendon to be more vulnerable to injury.
A ruptured tendon is a more serious and debilitating event than a strain. In a rupture, the tendon fibers will be either partially torn or completely severed, creating the rupture. The injury will be immediately apparent to the athlete as the rupture, either partial or full, will produce sharp and significant pain in the region of the injury, as well as immediate swelling. This injury will either significantly reduce or eliminate the function of the tendon. A ruptured tendon most commonly occurs through an explosive movement by an athlete, such as a jump, or a very sudden pivoting or accelerating movement.
The common musculoskeletal regions for tendon injuries are vulnerable to both the onset of tendonitis as well as ruptured tendon. The wrist is one such area, at the point where the tendons that connect the forearm muscles meet the bones of the wrist. These tendons that assist in the rotation, flexion, and extension movements of the wrist are particularly vulnerable to tendinitis, especially in sports that require the throwing of an object, or repetitive grappling and grasping movements.
The elbow is susceptible to tendon injury at both the medial (inside) and the lateral (outside) epicondilytis, the tissues that surround the elbow joint, providing a connection between the humerus (upper arm) and the radial and ulnar bones (forearm). In sports that involve considerable repetitive motion, such as tennis, golf, and baseball pitching, these structures are exposed to overuse and resulting tendinitis.
The rotator cuff is an assembly of four muscles connected by tendons to the bones of the shoulder joint, the humerus, and the scapula (shoulder blade). The rotator cuff tendon is vulnerable to both tendinitis through repetitive strain, as well as a rupture in a single act of excessive force. The rotator cuff, positioned at the top of the shoulder mechanism, is also particularly susceptible to damage due to imbalances between the muscles surrounding the shoulder, particularly the biceps and the muscles that power the movement of the scapula.
The patellar tendon and the quadriceps (thigh muscles) tendon are tissues that connect the patella (kneecap) above and below the knee. Repetitive jumping, as in basketball, volleyball, or the high jump, can result in a tendinitis known as jumper's knee. In more rare occasions, often when the tendon has been already weakened through tendinitis, either of these tendons may rupture in the course of a single movement.
Achilles tendon injury is of particular athletic concern. The longest and the strongest tendon in the body is the connection between the gastrocnemius and soleus muscles (calf muscles) of the lower leg, and the calcaneus (heel bone). The Achilles tendon is particularly vulnerable to injury because this structure is exposed to stresses with every upright movement of the body. All sports where the athlete walks, runs, or jumps can create circumstances where tendinitis may arise. The Achilles tendon is the most vulnerable tendon in the body for tearing or rupture, given its length and the frequency of movement. With the Achilles tendon, complete recovery from a rupture, in the sense of healing in the tendon fibers, will often result in a degree of permanent loss of some flexibility in the tissue.
A tendon rupture will usually involve surgical repair, and the requirement of a cast on the damaged area for a number of weeks following. Tendinitis is treated in a variety of ways, subject to the severity of the condition. All types of tendinitis benefit from the RICE (rest/ice/compression/elevation) treatment, which serves to reduce the swelling and the inflammation of the injury. In some circumstances, lightweight and inflatable air casts have been used to assist with protection and the rehabilitation of the injury. The return to activities must be gradual, with stretching and a focused effort to ensure balance between the adjacent musculoskeletal groups essential. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen will often assist in managing pain. For a jumper's knee condition, an infra-patellar strap, an orthotic that is a flexible band-shaped device wrapped securely around the patellar tendon to support the jumping movement, is also used.
There are a number of preventative measures to be taken by athletes regarding the onset of tendinitis. Shoe selection is important. A proper fit, suited to the characteristics of the athlete, will reduce the structural problems that may lead to the development of Achilles tendinitis. For runners, scouting out the training surfaces is important. Running intervals on hard, angled, or hilly routes without proper buildup or stretching may magnify the risk of Achilles tendon injury.
SEE ALSO Achilles tendon rupture; Achilles tendonitis; Elbow injuries; Hamstring pull, tear, or strain; Lower leg injuries; Musculoskeletal injuries; RICE (rest/ice/compression/elevation) treatment for injuries.