Tendons are the tough, white, fibrous cords that connect muscles to movable structures such as bone or cartilage. The presence of tendons allows muscles to act at a distance and concentrates the force of the muscle into a small area. Sometimes tendons can change the direction of a muscle’s pull, thus allowing the muscle to act around a joint. The structure of a tendon consists of parallel bundles of collagen fibrils, which makes it extraordinarily strong. A sheath, or vagina fibrosa, surrounds the tendon and is responsible for holding it in place. Between the fibrils and the sheath lie a lymphatic network and a fluid that allow tendon movement without excessive friction. Because of the vital functions of tendons, diseases and injuries to them can be debilitating as well as painful. Damaged tendons tend to heal slower than epithelial tissue, for example, because tendons have a lower blood supply than other soft tissues.
Trauma to tendons usually occurs in conjunction with impact, twisting, overstretching, or the simple overuse of a joint. These actions commonly result in partial or complete tears of the fibrous cord. Only if a tendon has not been stretched more than 4 percent of its original length will it return unchanged to its normal state once the force is released. When it is stretched from 4 to 8 percent of its normal length, the molecular bonds between individual collagen fibers begin to fail and the fibers slide past one another. At 8 to 10 percent strain, the tendon itself is in danger of tearing because individual fibers rupture, placing even more force on the fibers that remain intact. Although Golgi tendon organs send signals to the brain regarding excessive strain on tendons, such tearing usually occurs quickly during physical activities. Pain, swelling, and abnormal motion at the joint follow the damage. Tendinitis is the name given to the inflammation of a tendon.
Tendon disorders of the upper body. Tennis elbow, or lateral epicondylitis, involves the elbow joint and can be attributed to excessive extensor movements in the wrist joint and a sustained gripping of objects such as a tennis racket. There is great diversity in opinion as to the development of this disorder, as well as to its treatment. The latter includes methods such as rest, stretching, icing, heat, ultrasound, bracing, and surgery. Golfer’s elbow is less often seen but is a similar tendinitis of the common flexor tendon.
Supraspinatus tendinitis, or swimmer’s shoulder, is seen in athletes participating in swimming, tennis, and other activities involving overhead arm movement. Repeated overhead arm swings impinge and sometimes tear the supraspinatus tendon located between the acromion and the proximal end of the humerus. The disorder has also been termed impingement syndrome. Treatments include icing, stretching, modifying stroke technique in swimmers, anti-inflammatory drugs, and surgery.
Bicipital tendinitis usually stems from sports that require throwing or paddling. This type of tendon disorder is similar to the supraspinatus type in that pinching of a tendon is involved. The narrow tendon connecting the long head of the bicep muscle to the scapula lies in a groove and is restrained by a ligament therein. Pain occurring while a physician applies pressure to this groove and moves the patient’s arm is diagnostic for this particular tendinitis. Treatments are the same as for supraspinatus tendinitis and are almost always successful.
Vigorous throwing can produce triceps tendinitis. Other tendons prone to injury are those attaching the infraspinatus, teres minor, and teres major muscles. Indeed, any tendon may incur damage depending on the specific activities that an individual undertakes.
Synovitis of the wrist extensor tendons is the result of friction between the tendon, its surrounding sheath, and bone processes. Tenosynovitis brings about a thickening of the tendon sheath, and at times a rubbing sound can even be heard during movement. An aching pain develops and may be relieved by methods applied in tendinitis cases. In addition, ultrasound therapy in water is highly successful. The abductor pollicis longus and the extensor pollicis brevis muscles are most often affected.
Tendon disorders of the lower body. Tendons of the lower body undergo greater stress than tendons of the torso because a greater weight is moved and a more continuous motion is involved. Achilles tendinitis often occurs in people participating in sports involving running and jumping. This type of inflammation has become the most common athletic injury. When great tensile strength is needed, the tendon tends to be long compared with the muscle to which it attaches. The Achilles tendon is long and durable but twists as it descends down the lower leg, making certain areas of the tendon vulnerable to the concentration of stress. Quality footwear with slight heel elevation and heel padding can reduce the tearing effect on this tendon. Stretching the gastrocnemius and soleus muscles before athletic exertion ensures that these muscles will absorb a greater portion of the force that would otherwise be transferred to the tendon.
Jumper’s knee, or patellar tendinitis, is fairly common in basketball and volleyball players; it is often mistaken for arthritis of the knee. Repetitive extending of the leg at the knee causes microtearing in the kneecap tendon; thus, the torn fibers fray and eventually begin to degenerate. More stress than before is then placed on the remaining intact fibers, resulting in the likelihood of their failing as well.
Many other lower body injuries may involve tendons. Groin pull is most frequent in soccer players because of the sudden stresses involved in kicking and changing direction by planting cleats firmly into the ground and jolting the body into a new configuration. Hamstring pull occurs during bursts of sprinting because the hamstring functions in the forward movement of a leg after a stride is completed. During extremely fast running, the hamstring requires great force to keep pace; thus, damage to the connecting tendon and to the muscle itself is likely to occur if attention is not given to proper stretching techniques before the exertion.
The term “shin splints” refers to several painful injuries to the lower leg. Indicative of shin splints are pain and tenderness along the tibia, or shinbone, and the middle one-third of the leg. The condition develops in athletes who do not use sufficient padding in their shoes or who run and play on hard surfaces. Genuine shin splints do not involve tendons directly; fortunately, tendinitis of the tibial muscles can be differentiated from true shin splints because the pain of tendinitis is located higher up on the leg.
Compartment syndrome is most frequently seen in runners. The leg is divided into three compartments, each encompassed by a tight fascial sheath. When injury occurs to muscles or tendons of a certain compartment, swelling accompanied by a cutting off of the blood supply can cause further problems. Even the sudden growth of muscles as a result of physical activity can impair the function of muscles and nerves deeper in the leg.
Delforge, Gary. Musculoskeletal Trauma: Implications for Sport Injury Management. Champaign, Ill.: Human Kinetics, 2002.
Józsa, László, and Pekka Kannus. Human Tendons: Anatomy, Physiology, and Pathology. Champaign, Ill.: Human Kinetics, 1997.
Leach, Robert E., and Teresa Briedwell. "Tendinopathy." Health Library, Mar. 18, 2013.
Stanish, William D., Sandra Curwin, and Scott Mandell. Tendinitis: Its Etiology and Treatment. New York: Oxford University Press, 2000.
"Tendinitis." MedlinePlus, May 9, 2013.
"Tendinitis and Bursitis." American College of Rheumatology, Feb. 2013.
Weintraub, William. Tendon and Ligament Healing: A New Approach to Sports and Overuse Injury. 2nd rev. ed. Brookline, Mass.: Paradigm, 2003.
"What Are Bursitis and Tendinitis?" National Institute of Arthritis and Musculoskeletal and Skin Diseases, Apr. 2011.
No comments:
Post a Comment