Hip Joint Involvement

Osteoarthritis of the hip (malum coxae senilis) is a major crippling and painful form of osteoarthritis. Standing and walking often cause severe localized hip pain that may radiate laterally as well as to the medial aspect of the thigh and knee. The articular cartilage becomes thin, cysts form in the femoral head and acetabulum, the bone softens, and the femoral head flattens. Osteophytes grow from the head of the femur and around the rim of the acetabulum (see Plates 5-26 and 5-27). As a result, joint motion becomes markedly restricted, leading to a fixed deformity of the hip in flexion, adduction, and external rotation. Trochanteric bursitis causing pain at the lateral aspect of the hip is often misdiagnosed as hip osteoarthritis.

Spine Involvement

Degenerative disease of the spine occurs to some degree in almost every person past middle age, but the severity and speed of progression vary greatly. Two types of spinal degeneration are characteristic: one affects the intervertebral discs and their adjacent vertebrae, and the other affects the diarthrodial, or apophyseal, joints. Degeneration of the cartilaginous discs with secondary pathologic changes commonly occur in parallel with facet disease. With aging, the intervertebral discs lose water and the gelatinous central core (nucleus pulposus) becomes hard and brittle. Defects develop in the surrounding fibrous material (anulus fibrosus), which becomes fibrillated. Fissures develop in the anulus fibrosus, through which the nucleus pulposus may herniate. The disc deteriorates and becomes thin, and disc fragments (and sometimes the entire degenerated disc) may become displaced and press on the spinal nerve roots. The vertebrae on either side of the thin disc become closer, putting a strain on the facets (see Plate 5-28). Bony spurs grow and protrude from the vertebral margins, sometimes uniting to form a bony bridge between the vertebrae. Intervertebral disc degeneration occurs chiefly where movement is greatest—in the cervical, lower thoracic, and lumbar regions. Movement of the spine causes localized pain, which is intensified by strenuous activity, especially lifting heavy objects.