The hip

The hip is one of the ‘bread-and-butter’ joints in orthopedics, and provides a very substantial proportion of the total workload of an orthopaedic surgeon. In infants the problem of congenital dislocation of the hip is important because it is treatable if diagnosed early. The hip is also susceptible to septic arthritis, especially in the newborn (Table 23.1). In children, Perthes’ disease, an avascular necrosis of the hip, poses a major therapeutic challenge. In the young adolescent slipped upper femoral epiphysis needs early diagnosis if problems are to be avoided for the rest of the child’s life. In the young adult hip dysplasia may start to cause problems which will eventually go on to arthritis of the hip and which will pose severe problems for future hip replacement. In the elderly primary osteoarthritis of the hip is so common that, in Britain alone, over 50 000 total hip replacements are performed each year. Osteoporosis and problems of balance in the elderly also brings about a rapid rise in the incidence of fractured neck of femur. This, too, requires surgical treatment, providing the majority of major operations needed in trauma services.

Principles of history and examination of the hip

Pain localisation and radiation

Patients find pain originating from the hip very difficult to localise. Children presenting at the clinic with a limp, a painful knee and a normal knee X-ray (King’s triad) will usually be found to have a problem in the hip not the knee. Similar problems occur in the elderly, who may complain of pain down the front of the thigh and into the knee, when the diagnosis is osteoarthritis of the hip. However, pain originating from the back can radiate down into the buttocks into the greater trochanter. Examination of a patient complaining of pain in the hip needs to concentrate on determining whether this pain is arising from the spine, the knee or the hip itself.

Disability activities of daily living

Patients with a stiff hip complain primarily of difficulty getting in and out of the bath and low chairs, as well as problems with getting socks and shoes on. The combination of pain and stiffness from osteoarthritis may also limit their walking distance.

Deformity

Problems in the hip lead to flexion and adduction of the joint. This leads to a tilt of the pelvis and a leg which appears to be shortened. The patient will therefore stoop and limp because of pain, weakness and deformity.

Osteoarthritis

Most osteoarthritis is called primary because there is no known preceding cause. There is a genetic effect, but the reason why some joints apparently last the lifetime of a patient while others disintegrate is not well understood. Secondary arthritis can occur following congenital subluxation of the hip, Perthes’ disease secondary to trauma or an inflammatory arthritis such as rheumatoid (see Table 23.2).

Prevention

There is some evidence that young people involved in high-intensity sport and/or heavy-duty work are more susceptible to osteoarthritis later in life, but the affect is surprisingly small. Secondary osteoarthritis may be prevented by mini­missng the damage to the joints caused by the primary disease. In trauma articular fractures should be anatomically reduced. In inflammatory joint disease every effort should be made to reduce the level of inflammation.

Treatment

In the early stages osteoarthritis affects the patient in all three main areas of orthopaedic endeavour. It causes pain, disabil­ity and some deformity. It may also cause high levels of anxiety in the patient who may be worried that the condition is going to rapidly deteriorate and spread to other joints, destroying their quality of life. Many patients are resistant to taking tablets of any sort. There is no evidence that pain killers or anti-inflammatory drugs do anything but relieve the symptoms, and they may even accelerate the pathological changes. The key issue at this early stage for the quality of life of the patient is to maintain mobility and to avoid deformity. Physiotherapy should be used to show the patient how to keep joints mobile and muscles in good condition. The psy­chological benefit of this is also almost certainly important.

More severe osteoarthritis

As the condition becomes more severe regular analgesia may be needed. The use of centrally acting pain killers, such as paracetamol, combined with nonsteroidal anti-inflammatory drugs appears to provide a synergistic effect in terms of pain relief, but care must be taken to avoid gastric irritation and ulceration.

Indications for joint replacement

Indications for joint replacement are:

pain;

stiffness;

loss of independence.

In the elderly, loss of independence through disability is a crucial issue. A painful stiff and deformed hip may prevent a person from sleeping, from doing up their shoes, from going out to do their shopping and even from using a car or a bus. This combined with chronic pain may convert a cheerful outgoing involved member of society into a depressed and isolated individual reliant on others for their needs. The cost to the individual and to society is out of all proportion to the pathological effect of the disease itself. A total hip replacement reverses this cycle. Combined with the judicious use of physiotherapy and occupational therapy, this gives the patient the confidence to return to an active independent life. In the patient over 65 years with a life expectancy of around 20 years, total hip replacement is the treatment of choice for osteoarthritis. In the younger patient the likelihood is that the joint replacement will not last the lifetime of the patient. They can be replaced (a revision operation) but this is technically difficult and the next operation does not last as long as the first. In younger patients secondary osteoarthritis is more common than primary and in these patients fitting the hip replacement securely in the abnormal anatomy may be much more difficult than in a simple elderly patient. The patient may also put greater loads on the hip. If a patient has a normal life expectancy, the younger the patient the more carefully alternatives to total hip replacement must be considered.

Rheumatoid arthritis

Total hip replacement in patients with rheumatoid arthritis is a successful operation. Perhaps this is because the patient has put very little load on the hip, but the relief of pain and the increase in mobility can have a dramatic effect on the quality of life of the patient.