Osteoarthritis
Osteoarthritis is a ubiquitous disorder affecting all adults to a greater or lesser degree by the time they have reached middle age. It is not restricted to humans. The name osteoarthritis is a misnomer insofar as its suffix implies that the condition has an inherently inflammatory nature. For this reason it frequently is called degenerative joint disease or, in Europe, osteoarthrosis or arthrosis deformans. When the spine is involved, the corresponding term is spondylosis. Unlike rheumatoid arthritis, osteoarthritis rarely causes crippling deformities. In the majority of instances, the milder anatomical changes are not accompanied by appreciable symptoms. There are no systemic complaints directly attributable to the joint disease. The changes are characterized by abrasive wearing away of the articular cartilage concurrent with a reshaping of adjacent ends of the bones. As a result, masses of newly proliferated bone (osteophytes) protrude from the margins of the joints.
The clinical manifestations of osteoarthritis vary with the location and severity of the lesions. The most disabling form occurs in the hip joint, where it is known as malum coxae senilis. Osteoarthritis of the hip, like that of other joints, is classified as primary and secondary. In secondary osteoarthritis, the changes come about as a consequence of some antecedent structural or postural abnormality of the joint. In about half the cases, however, even rigorous examination fails to disclose such an abnormality; in these instances, the osteoarthritis is called primary.
Probably the most frequent cause of osteoarthritis of the hip is congenital dysplasia (dislocation or subluxation of the hip). This term refers to a poor fit of the head of the femur, the long bone of the thigh, with its socket in the pelvis, the acetabulum. There is impressive evidence that many cases arise in infancy as a consequence of swaddling infants or carrying them in headboards, procedures that keep the thighs in an extended position. Before the child is ready for walking, the hip joint has frequently not yet fully developed and the head of the femur is forced out of its normal position by this extension.
Osteoarthritis of the hip occurring in relatively young persons--in their 30s or 40s--frequently follows a progressive course and requires surgical treatment. Two rather different strategies of surgery have been employed: one, an osteotomy, involves reshaping the upper end of the femur so that the load borne by the joint is distributed more efficiently; the other requires removal of the diseased tissue and replacement by an artificial joint.
Aside from the rapidly developing forms, osteoarthritis of the hips also appears frequently in aged persons. Chronologic aging is an important factor in the development of other forms of degenerative joint disease as well, since the lesions increase in frequency and severity as time passes by.
Considerations like these have led to the view that the principal causative factors in degenerative arthritis are faulty mechanical loading and senescent deterioration of joint tissue. Single injuries, unless they leave a joint permanently deformed, rarely result in osteoarthritis. Recurrent small athletic and occupational injuries, such as those arising from heavy pneumatic drill vibrations, apparently are more likely to do so. Lifting heavy weights has been implicated in some studies of spinal involvement.
Aside from surgery of the sort noted in the hip and sometimes the knee, the treatment program is rest and proper exercise, avoidance of injury, the use of analgesics to relieve pain, and several types of physical therapy.
Chondromalacia patellae is a common and distinctive softening of the articular cartilage of the kneecap in young persons, particularly young athletes. It results in "catching" and discomfort in the region of the patella, or kneecap, as the knee is bent and straightened out. Pathologically the changes are indistinguishable from changes that occur early in osteoarthritis. The condition often responds poorly to conservative measures and is treated surgically.
Degeneration of the intervertebral disk is a frequent and in some ways analogous disorder. Often this occurs acutely in young and middle-aged adults, and the pulpy centre of the disk pushes out through tears in the fibrous outer ring (so-called slipped disk). When this takes place in the lumbosacral region, the displaced centre (the nucleus pulposus) impinges on the adjacent nerve roots and causes shooting pains in the distribution of the sciatic nerve--hence the name sciatica. Pain in the small of the back is loosely referred to as lumbago, or lumbosacral sprain. It may be associated not only with degeneration of the intervertebral disk and spondylosis but also with structural anomalies of the region. Principal among these is spondylolisthesis, in which there is an anterior displacement of one lumbosacral vertebral body on another. The episodes respond to bed rest and mechanical support from wearing an abdominal corset or brace. Muscle relaxants may be of value. Recurrences are prevented by avoidance of back strains. Muscle-strengthening exercises are frequently helpful. The protruding tissue is removed by surgery only in cases in which pain and neurological defects are severe and fail to improve after less drastic measures.