The hip is a major site of degenerative joint disease, with the elderly being the most affected. Obesity is also a risk factor, particularly in women. The onset is often insidious, beginning with minor aching or stiffness that may be unilateral or bilateral. Symptoms are characteristically exacerbated by prolonged standing, walking, or stair climbing. Stiffness is noted when the patient gets up after sitting for long periods. The hip begins to loosen up at first with moving about, but discomfort then worsens with continued activity. As osteoarthritis gradually progresses, it results in decreasing hip motion, increasing stiffness, and increasing pain. A limp may develop as the joint architecture is disrupted, and weight bearing becomes painful. The course of the disease is usually marked by spontaneous exacerbations and remissions.

On physical examination, the patient with substantial disease characteristically holds the hip in flexion, external rotation, and adduction. An antalgic gait, Trendelenburg sign (buttock falls when the patient stands on the opposite foot, which is indicative of abductor weakness), and limitation of hip motion with or without crepitus may be present. Pain, muscle spasm, and guarding occur when the examiner attempts to take the hip through the full range of motion. Buttock atrophy may involve the gluteus maximus posteriorly and the gluteus medius more laterally. With severe degenerative arthritis of the hip, a marked flexion deformity may develop, and pain may be felt in the hip joint even at rest (see also Chapter 157).

The hips are rarely affected in rheumatoid disease until other joints have become involved. Pain is characteristically bilateral and associated with morning stiffness, which lessens with activity. During flares of the disease, the hip joint is tender to palpation, and capsular fullness and thickening may be felt if effusion or chronic synovitis is present. Flexion contractures occur in advanced cases (see also Chapter 156).

Of the spondyloarthropathies, this one is unique in that the hip is sometimes affected. Concurrent sacroiliac (SI) and spinal involvement is usually present and in itself may cause pain radiating into the hip or buttock (see also Chapters 146 and 147).

Hip fracture is common source of morbidity and mortality among the elderly. One in three women and one in six men will have a hip fracture by the ninth decade. Mortality is as high as 30% with a five- to eightfold increase in mortality risk during the first 3 months of fracture. At greatest risk are the frail elderly with a history of frequent falls, previous fracture, or osteoporosis. A low serum 25-OH vitamin D concentration is also an independent risk factor, conferring an increase in relative risk that varies inversely with the serum level (77% increase in risk for women in the lowest 25-OH vitamin D quartile). The femoral neck and intertrochanteric region are common fracture sites. Competitive long-distance runners are also at risk for stress fracture of the femoral neck.

Prolonged use of bisphosphonate therapy is an independent risk factor for atypical fractures of the femoral shaft. Although the relative risk is very high (47.3), the absolute risk is low (5 per 10,000 patient years of bisphosphonate use). Risk declines by 70% per year after drug withdrawal. Among factors that lower risk of hip fracture are bisphosphonate therapy in women who are osteoporotic, vitamin D supplementation in persons who are vitamin D deficient, and cataract surgery in the elderly.

Clinically, the resultant loss of normal surface architecture may be associated with acute joint deformity leading to severe pain, guarding, and restriction of flexion and external rotation; active straight leg raising is impaired.

Septic arthritis of the hip may follow from hematogenous seeding or bacterial implantation during hip surgery. With hundreds of thousands of total hip replacements being done annually in the United States and a 0.3% to 1.7% risk of infection at surgery, the number of patients presenting with an infected prosthesis is likely to rise. Because the joint is deep-seated, the ordinary signs of infection may not be readily evident. Infection due to implantation at surgery of a virulent organism such as Staphylococcus aureus usually presents within 3 months of surgery as an acute infection,
initially with fever and severe joint pain on weight bearing, followed by swelling, redness, and warmth about the joint. The thigh is often held in flexion, and a bulging, tender joint capsule may be palpable. When due to a less virulent organism (e.g., coagulase-negative Staphylococcus species) and presenting as a more chronic infection months or years later, the septic joint may be manifest only by pain and a loosened bone-cement interface, sometimes accompanied by a small sinus tract. The leukocyte count may be normal, but C-reactive protein is usually elevated.

Also referred to as “aseptic” necrosis of the femoral head, this condition has an ischemic pathophysiology. It occurs with increased frequency in patients who take high daily doses of glucocorticoids, persons who are alcoholic, patients with hemoglobinopathies, and persons who work under conditions of increased atmospheric pressure. The mechanism of steroid-induced disease involves the proliferation of intramedullary fat, tissue hypertension, and compromised perfusion of bone. Patients report the gradual onset of focal pain and limitation of movement. Diagnostic radiographic changes include wedge-shaped areas of increased density and segmental collapse of the femoral head.

Inflammation of the bursa occurs as a consequence of trauma or spread of an inflammatory process. Focal pain with tenderness develops over the bursa. Trochanteric bursitis is felt on the lateral aspect of the hip, posterior to the trochanter. Symptoms are increased by direct pressure or hip flexion and internal rotation. Pain may worsen at night and radiate down the leg to the knee. It may occur in runners who jog on uneven surfaces and those with one leg slightly shorter than the other. Not all pain at the greater trochanter is bursitis, a fact revealed when pathologic examination found no evidence of bursitis in many patients presenting with pain and tenderness at the greater trochanter despite shortterm improvement with corticosteroid injection. Consequently, the term greater trochanteric pain syndrome has been suggested.

Iliopectineal bursitis causes pain on flexion and tenderness localized to the lateral border of Scarpa triangle. Ischiogluteal bursitis presents with buttock pain that is worse during prolonged sitting, occurs at night, and occasionally radiates down the leg posteriorly, simulating sciatica.

A disease of the elderly that is often mistaken for depression, arthritis, or bursitis, polymyalgia is characterized by bilateral aching of the hips, thighs, and shoulders in conjunction with a very high sedimentation rate. It has a strong association with cranial arteritis (see Chapter 161). Joint structures and passive range of joint motion are usually preserved.

Although not a characteristic joint for an attack of gout or pseudogout, the hip may be the site of an attack, presenting as acute onset of inflammatory hip pain in a patient with a history of gout or pseudogout. Pseudogout can occur in a joint with degenerating cartilage, and gouty arthritis may predispose to degenerative changes in the joint.

The iliotibial band forms from the amalgamation of fascia from the hip flexors, extensors, and abductors, originating at the lateral iliac crest and extending distally to the patella and tibia. Strenuous repetitive hip or knee flexion and extension, as in sports that require continuous running, can cause inflammation either at the proximal origin, producing lateral hip pain or more commonly at the distal insertion resulting in lateral knee pain. There is pain and tenderness along the band, worsened by putting stress on the band (e.g., moving the extended leg down and forward while in the lateral decubitus position with the involved hip up).

A femoral bony metastasis typically occurs in the context of known metastatic cancer. Pain is typically felt in the lateral aspect of the hip and worsened not only by weight bearing but also by direct pressure; it may extend into the night or be continuous.

This uncommon granulomatous disease of the synovium presents with slowly progressive pain and limitation of movement. Radiographic films show large cystic areas about the hip joint, which distinguish the condition from degenerative joint disease.

Lumbar disk herniation and spinal stenosis that compress lumbar nerve roots may result in pain referred in a radicular distribution to the posterior and lateral hip area, groin, and down the leg, depending on the particular roots involved. The pain from spinal stenosis may simulate that of another possible cause of referred hip pain, aortoiliac disease, in being worsened by walking and relieved by rest or sitting (so-called pseudoclaudication— see Chapter 147). The pain of lumbar disk herniation is typically worsening by prolonged sitting. Superficial nerve compression leading to the lateral femoral cutaneous nerve syndrome, seen with wearing of tight garments or obesity, may produce a circumscribed area of paresthesias and burning pain in the lateral hip and adjacent upper thigh that is not affected by activity, back movement, or direct pressure.