Affections of joints 1

ARTHRITIS

The term arthritis is used here to include both inflammatory and degenerative lesions of a joint. It implies a diffuse lesion affecting the joint as a whole. It does not include localized mechanical disorders such as loose body formation or tears of the menisci of the knee, which are better designated as internal derangements.

Clinically, arthritis is generally characterized by pain and restriction of movement at a joint, arising spontaneously; in superficial joints these features are usually accompanied by obvious swelling or thickening. If a joint is not swollen and if it moves freely and painlessly through its normal range it is very unlikely that it is affected by arthritis.

Types of arthritisIt may be said that there are four common

types of arthritis, and several less common or rare varieties. The incidence of different "types varies greatly from country to country and from continent to continent, racial influences or differing standards of general hygiene often being important.

The four types of arthritis that are common, taken worldwide, are:

1)Pyogenic arthritis 2)Rheumatoid arthritis and juvenile chronic arthritis; 3)Tuberculous arthritis and 4)Osteoarthritis. Other types of arthritis that will be considered are:• Gouty arthritis; • Haemophilic arthritis; • Neuropathic arthritis (Charcot's osteoarthropathy);• The arthritis of rheumatic fever; and • Ankylosing spondylitis.

PYOGENIC ARTHRITIS(Infective arthritis; septic arthritis)

In this form of arthritis a joint is infected by bacteria of one of the pyogenic groups. Typically there is acute joint infection of rapid development, but the infection may be subacute or even chronic. When pus is formed within the joint the condition is sometimes termed suppurative arthritis.

Cause. The staphylococcus, streptococcus or pneumococcus is usually responsible—occasionally the gonococcus or other organisms.

Pathology. The organisms may reach the joint by three routes:

1)Through the blood stream (haematogenous infection); 2)Through a penetrating wound; or 3)By extension from an adjacent focus of osteomyelitis

The infection causes an acute or subacute inflammatory reaction in the joint tissues. There is exudation of fluid within the joint: the fluid is turbid or frankly purulent according to the severity of the infection. The outcome varies from complete resolution, with normal function, to total destruction of the joint and fibrous or bony ankylosis .

Clinical features. The onset is acute or subacute, with pain and swelling of the joint. There Is constitutional illness, with pyrexia.

On examination the joint is swollen, partly from fluid effusion and partly from thickening of the synovial membrane. When the affected joint is superficial, the overlying skin is warmer than normal and it is often reddened. All movements are restricted; in' severe cases they are almost totally prevented by protective muscle spasm. Attempted or forced movement increases the pain. In cases of haematogenous infection a boil or other primary focus of infection is often to be found elsewhere in the body. In other cases there may be a history of penetrating injury, or of bone infection adjacent to the joint.

Radiographs in the early stages do not show any

alteration from the normal (Fig. 90). Later, if the infection persists, there may be diffuse rarefaction of bone adjacent to the joint, loss of cartilage space, and possibly destruction of bone (Fig. 91). Radioisotope bone scanning shows increased uptake of the isotope in the region of the joint.

Investigations. There is a polymorphonuclear leucocytosis. The erythrocyte sedimentation rate is raised. Bacteriological examination of aspirated joint fluid usually identifies the causative organism.

Diagnosis. This is from other forms of arthritis

(especially tuberculous arthritis, gouty arthritis, and haemophilic arthritis), and from infections near the joint. This varies widely according to the severity "of the infection, the organism, responsible, and the promptness with which efficient treatment is begun. Many joints can be saved intact, but many are destroyed more or less completely, with fibrous or bony ankylosis (Fig. 89).

Fig. 8.9 Pyogenic arthritis, with possible results. In the active phase the joint is distended with pus or turbid fluid; the synovial membrane is inflamed and moderately thickened. The outcome varies with the intensity of the infection and the response to treatment. There may be: 1) "restoration to normal; 2) fibrous ankylosis; or 3) bony ankylosis.

Treatment. Very prompt treatment is essential if there is to be a reasonable prospect of preserving normal joint function.

Constitutional treatment. This is by rest in bed and appropriate antibiotic drugs. Whenever possible the causative organism must be identified by culture of the blood and of joint aspirate and its sensitivity to antibiotics determined, so that the most effective drug may be given. Until that information is available treatment should be begun with flucloxacillin, either alone or in combination with fusidic acid.

Fig. 90 Fig.91Pyogenic arthritis of the wrist. Figure 90—Initial radiograph, with no apparentabnormality. Figure 91—Four weeks after onset. Note the rarefaction of the bones andthe slight but significant narrowing of the cartilage space, indicating destruction ofarticular cartilage. (See also Fig. 55, p. 73.)

Local treatment. The joint is rested, usually in a plaster splint In the case of the hip or knee, sustained weight traction is useful in relieving spasm and pain. The fluid exudate, which is often purulent, is removed by aspiration or, if necessary, by incision. At the same time a solution of the appropriate antibiotic drug is injected into the joint. Rest is enforced until the infection is overcome, as shown by the subsidence of pyrexia and retrogression of the local signs. Thereafter active movements are encouraged in order to restore the greatest possible function to the joint.

RHEUMATOID ARTHRITIS (Rheumatoid polyarthritis)

Rheumatoid arthritis is a chronic inflammation of joints, often associated with mild constitutional symptoms. It nearly always affects several joints at the same time (polyarthritis). Joint changes of a similar nature also occur in a number of other conditions such as juvenile chronic arthritis (Still's disease), Reiter's syndrome, psoriasis, lupus erythematosus and other connective tissue or collagen diseases.

Cause. The cause is unknown. At present only two possibilities attract serious consideration:

1) The disease is due to autoimmunity; and 2) It is caused by infection. The hypothesis of auto-immunity,

possibly to type II collagen , is based mainly on the observation

that the serum of many patients with rheumatoid arthritis contains an antibody known as rheumatoid factor, which reacts with the body protein gamma globulin. When, the antibody is present the disease is termed 'seropositive', as contrasted with seronegative arthritis when the antibody is absent. The source of the antigen, and many other details of the mechanism by which rheumatoid factor is formed, are unknown.

The hypothesis of infection is likewise without sure foundation. Infection possibly by a virus or by organisms of the mycoplasma or diphtheroid group may result in liberation of antigenic type II collagen from the patient's own articular cartilage.

Rheumatoid arthritis; with possible results. In the active phase there "is marked thickening of the synovial membrane. Later, the articular cartilage is often eroded and in severe cases there may be some destruction of bone. The possible results are: 1) restoration to normal (only after mild disease of short duration); 2) continuing mildly active disease with permanently damaged joint surfaces and restricted movement; and 3) secondary osteoarthritis from wear-and-tear degeneration of the damaged joint surfaces.

Restoration to Quiescent disease: Secondary osteoarthritisnormal joint surfaces damaged ' (years later)

Pathology.

The synovial membrane is thickened by chronic inflammatory changes: characteristically it is infiltrated with macrophage-like cells and T-cell lymphocytes (Fig. 92). Later the articular cartilage is gradually softened and eroded, and the subchondral bone may also be eroded, characteristically at the joint margins probably from the action of lytic enzymes and inflammatory mediators produced in the thickened synovial membrane.

The pathological changes are not confined to joints ,the synovial lining of tendon sheaths may be similarly inflamed and thickened, both in the hands and in the feet. The contained tendons may become softened and may rupture, aggravating any existing deformity. Inflammatory nodules may form in the soft tissues.

After months or years of activity the disease process tends to become less active, usually leaving a number of joints that are permanently damaged, with consequent deformity, instability, or ankylosis.

Clinical features.

The patient is usually a young or middle-aged adult, and is more likely to be a woman than a man. Any joint may be affected, but the incidence is higher in the more peripheral joints such as the hand joints, wrists, feet, knees, and elbows than- in the lumbar or thoracic spine, shoulders, or hips. The onset is gradual, with increasing pain and swelling of a joint. Soon a number of other joints are similarly affected. Pain and stiffness are often worst when activity is resumed after resting. Often there is constitutional disturbance, with tiredness and anemia, and occasionally fever.

On examination: the affected joints are swollen from synovial

thickening. The overlying skin is warmer than normal. The range of joint movements is restricted, and movement causes pain, especially at the extremes. These clinical features are often more severe in seropositive disease than when rheumatoid factor is absent from the serum.

It is important always to study the condition of the cervical spine, which is commonly affected. Despite relatively minor symptoms, destruction of ligaments and bone may sometimes lead to'subluxation of such degree that the spinal cord is in jeopardy, and it is important always to be wary of this possibility.

Extra-articular features may include enlargement of lymph nodes, muscle wasting, subcutaneous rheumatoid nodules, and anemia.

Imaging. Radiographic features: At first there is no alteration from the normal. Later, there is diffuse rarefaction in the area of the joint. Eventually destruction of joint cartilage may lead to narrowing of the cartilage space and, in severe cases, to localized erosion of the bone ends (Fig. 94). Radioisotope bone scanning shows increased uptake of the isotope in the region of affected joints.

Investigations. Both the erythrocyte sedimentation rate and C-reactive proteins are raised during the active phase. The latex fixation test and if necessary the Rose-Waaler sheep cell agglutination test are used to determine whether or not rheumatoid factor is present in the serum.

Fig. 93Joint damage in rheumatoid arthritis. Left—Long-established rheumatoidarthritis of the knee. Note the rarefaction and loss of cartilage space.Right—Destruction of the elbow joint in a case of severe rheumatoid arthritisof long duration.

Diagnosis. The clue to the diagnosis is the simultaneous

involvement of several joints, with" raised sedimentation rate. The presence of rheumatoid factor in the blood is highly suggestive, though the tests are "not specific for rheumatoid arthritis; and rheumatoid factor may be absent in about 20 per cent of patients even in well established rheumatoid arthritis.

N.B A- search should always be made for evidence of one of the distinct medical entities that may be associated with joint changes of a rheumatoid type .The most important of such conditions "are:

1) Psoriasis; 2) Reiter's syndrome (urethritis, arthritis, conjunctivitis, and

hyperkeratotic eruptions on the skin); 3) Lupus erythematosus (scaly erythema of face, or other

parts); and 4) Scleroderma. These conditions are all seronegative, and

they may be associated with ankylosing spondylitis Course. There is a tendency for rheumatoid arthritis to become quiescent after remaining activejor months or years. In most cases there is permanent impairment of joint function. In certain joints especially in the knees degenerative changes are often superimposed upon the previous rheumatoid condition, and lead to increasingly severe disability even though the original rheumatoid affection is no longer active.

Treatment. The treatment of rheumatoid arthritis is unsatisfactory. No specific cure has been found. Immumerable drugs have been tried and many are in use; yet it is by no means certain opinions differ on this point that any of them has an influence on the duration of the disease or on its eventual outcome' in a particular case.

Methods of treatment may be classified into die following categories:

1) Rest and constitutional treatment; 2) Drugs, which include mainly the various nonsteroidal anti-

inflammatory agents; 'second-line' drugs such as gold salts, sulphasalazine and penicillamine; and (rarely) the ‘third-line' corticosteroids;

3) Intra-articular injections of hydrocortisone; 4) Physiotherapy; 5) Occupational therapy; and 6) Operation.

1-Rest and constitutional treatment:Rest is thought to be beneficial; especially in the

early stages of the disease and during an exacerbation. At many centers patients are admitted to hospital at the outset for a period of rest lasting one or two months, and sometimes this temporary removal from the home environment, with skilled nursing, regular food and proper sleep, has a remarkably good effect on the general health, which is often impaired in these cases.

Rest for individual joints is also helpful during the initial active stage of inflammation, provided it is not enforced for too long. Convenient light splints for this purpose may be made from expanded polystyrene, or plaster of Paris may be used. Splintage is seldom required for more than two months, and should be followed by graduated exercises under the supervision of a physiotherapist.

2-Drugs. Drugs used in rheumatoid arthritis fall mainly

into the categories of non steroidal anti-inflammatory drugs, and the potent anti-inflammatory agents grouped under the heading corticosteroids. A logical plan is to use aspirin or a related salicylate as the first-line drug and to follow with other drugs if the response is unsatisfactory. Aspirin has both analgesic and mild anti-inflammatory properties but to be effective it may have to be given in fairly large doses. Alternative first-line drugs, after aspirin, should probably be chosen from the group of non-steroidal anti-inflammatory drugs which includes indomethacin, ibuprofen, naproxen, flufenamic acid and piroxican. Due regard must be paid to the risk of side effects: gastric pain is a common complaint with most of these drugs, and more serious complications, such as gastric bleeding, are seen occasionally.

3-Intra-articular injections, Injections of corticosteroids (usually hydrocortisone) into an affected joint can produce worth-while relief, but their disadvantages have precluded their widespread use. The main disadvantages are:

1)risk of infection, especially with repeated injections;

2)risk of accelerating a degenerative reaction, the mechanism of which is not yet clear;

3)the short duration of the relief obtained; and 4)repeated injections at several sites may become so

irksome to the patient as to be unacceptable. In general, it is wise to avoid repeated injections

4-Physiotherapy. Physiotherapy is widely used and generally beneficial, even though some of the benefit may result from suggestion or 'placebo effect' rather than from a direct effect on the disease process. Heat in the form of infrared radiation or short-wave diathermy is commonly used, but probably the most useful contribution of physiotherapy is active exercises, designed both to keep joints as mobile as possible and to maintain useful function in the muscles that control them.

5-Occupational therapy. Occupational therapy is useful mainly in helping seriously disabled patients to find ways in which they can more easily carry out the various activities of everyday life—bathing, toilet, cooking, feeding, boarding public transport, and many others. Many useful aids for the disabled are available, and those that are appropriate should be brought to the patient's notice.

6-Operation. Operation has an important place in treatment, but each operation must be considered as a component in the overall plan of management and not as a substitute for other measures. Operation may be applicable to the early stages of the disease, or it may be used in the later stages to salvage a joint that has been permanently damaged and remains a source of persistent pain.

In the early stages the operation most commonly used is synovectomy -excision of thickened and inflamed synovial membrane from joint or tendon sheath. As well as relieving pain, this may possibly slow down the inflammatory process and so help to preserve articular cartilage in an affected joint. It is undertaken mainly in the knee and wrist, and in the small joints and tendon sheaths of the hand.

Operation may also be required in the hand for repair or replacement of ruptured tendons, or for correction of finger deformities. In the painful elbow there is often a place for excision of the diseased radial head, arid at the wrist excision of the lower end of the ulna may bring worth-while relief in selected cases.

Operations used in the later stages are osteotomy, arthroplasty, and arthrodesis. Osteotomy is useful mainly for the correction of deformity, particularly at the knee. Arthroplasty is applicable particularly to the hip and knee, and sometimes to the shoulder or elbow, and to the joints of the fingers and toes. Arthrodesis is usually the operation of choice for the joints of the spine, the wrist and the ankle, and sometimes for the shoulder, the elbow and the knee.