A summary of the diagnostic strategy model is presented in TABLE 35.1.
Table 35.1Arthralgia: diagnostic strategy model ||Download (.pdf) Table 35.1 Arthralgia: diagnostic strategy model
Viral polyarthritis (e.g. parvovirus)
Serious disorders not to be missed
rheumatoid arthritis (RA)
connective tissue disorders: SLE, scleroderma, polymyositis and dermatomyositis, psoriasis, other
Pitfalls (often missed)
Ross River virus
Other vasculitides (e.g. polyarteritis nodosa)
Familial Mediterranean fever
Pigmented villonodular synovitis
Seven masquerades checklist
Diabetes (? arthropathy)
Drugs (especially narcotics)
Endocrine disorder (thyroid storm, Addison disease)
Spinal dysfunction (possible spondyloarthropathies)
Is the patient trying to tell me something?
Always a consideration with pain. Psychogenic factors aggravate chronic arthritic conditions.
The probability diagnoses for the patient presenting with arthritis are:
OA is very common in general practice. It may be primary, which is usually symmetrical, and can affect many joints. This clinical pattern is different from secondary OA, which follows injury and other wear-and-tear causes.
Viral polyarthritis is more common than realised. It presents usually within 10 days of the infection, and is usually mild.
Clinical features (viral arthritis)
Mainly of hands and feet
Rash—persists for 24 hours minimum
Terminates rapidly—over days
FBE: lymphopaenia, lymphocytosis, ± atypical lymphocytes
It tends to terminate quickly and spontaneously without permanent damage to joints. It is caused by many viruses, including those causing influenza, mumps, rubella, varicella, hepatitis B and C, infectious mononucleosis (more muscle aching), cytomegalovirus, parvovirus, Australian epidemic polyarthritis due to the alphaviruses, Ross River virus (see CHAPTER 28) and Barmah Forest virus. Adenovirus is common in children.
Serious disorders not to be missed
These include rheumatoid arthritis (RA), which can start as a monoarthritis; pyogenic arthritis, including gonococcus, Staphylococcus, Kingella sp. and Streptococcus infections; tuberculosis; rheumatic fever; and bacterial endocarditis. Early diagnosis of septic arthritis is very important as it can destroy a hip in 24 hours.
It is important to be forever watchful for rheumatic fever (RF). It presents typically as a migratory polyarthritis involving large joints sequentially, one becoming hot, red, swollen and very painful as the other subsides. It rarely lasts more than 5 days in any one joint.
A flitting polyarthritis can also occur with endocarditis in addition to a systemic upset and a cardiac murmur. Gonococcal infection may present in a single joint or as flitting polyarthritis, often accompanied by a rash. Brucellosis can cause arthritis and sacroiliitis and can be confused with the spondyloarthropathies.
HIV infection is becoming a great mimicker. It can present as a chronic oligoarticular asymmetrical arthritis.3 It can also present as a rash very similar to psoriasis.
With the large influx of migrants from South-East Asia the possibility of tuberculosis presenting as arthritis should be kept in mind.
Connective tissue disorders may be involved. They include SLE, progressive systemic sclerosis (scleroderma), and dermatomyositis. It is most inappropriate to settle with a general diagnosis such as ‘rheumatism’ or ‘arthritis’ and where doubtful it is important to find the specific entity causing the problem.
In respect to malignant disease, arthralgia is associated with acute leukaemia, lymphoma and neuroblastoma in children and with bronchial carcinoma, which may cause hypertrophic osteoarthropathy, especially of the wrist and ankle (not a true arthritis but simulates it). Occasionally polyarthritis may be the first feature of an occult neoplasm. Monoarticular metastatic disease may involve the knee (usually from lung or breast).
Red flag pointers for polyarthritis
There are several pitfalls, most of which are rare. A common pitfall is gout. This applies particularly to older women taking diuretics, whose osteoarthritic joints, especially of the hand, can be affected. The condition is often referred to as nodular gout and does not usually present as acute arthritis.
Fibromyalgia syndrome is a real puzzle (see CHAPTER 37) as it can mimic the connective tissue disorders in its early presentation—typically a woman in the third or fourth decade.
Another ‘trap’ is haemarthrosis in a patient with a bleeding disorder.
Infective causes that may be overlooked are dengue fever, especially in travellers returning from a tropical or subtropical area, and Lyme disease, which is now surfacing in many countries, especially where ticks are found.
There are many rare causes of arthritis. Sarcoidosis causes two forms: an acute benign form, usually in the ankles and knees, and a chronic form with long-standing sarcoidosis that involves joints (large or small) adjacent to underlying bone disease.
Then there are the uncommon vasculitides, which can cause confusion in diagnosis. This group includes polyarteritis nodosa, hypersensitive vasculitis, polymyalgia rheumatica/giant cell arteritis, Wegener granulomatosis, Henoch–Schönlein purpura and Behçet syndrome.
Haemochromatosis can present with a degenerative arthropathy that characteristically affects the second or third metacarpophalangeal joints.3
Other rare causes of arthritis are erythema nodosum, serum sickness and Sjögren syndrome.
Not searching beyond RA when an RA pattern polyarthritis may be part of another systemic disease
Failing to search for some cause of arthritis other than OA in a patient, especially an elderly patient (i.e. underdiagnosing); an important example of this is polymyalgia rheumatica
Failing to consider the various drug interactions between NSAIDs, over-the-counter medications and other drugs used by the elderly
Underdiagnosing and misdiagnosing through lack of appreciation of the many causes of arthritis, especially those presenting as part of a systemic disease
Drug-induced arthritis usually affects the hands and is generally symmetrical. The drugs may induce autoantibodies (e.g. ANA, ANCA). Those that include a lupus syndrome include the anti-epileptics, chlorpromazine and some cardiac drugs. Various antibiotics have been associated with arthralgia, e.g. minocycline, while diuretics, especially frusemide and thiazides, can precipitate gout. The problem usually resolves promptly after withdrawal of the agent.4
Intravenous drug abuse may be associated with septic arthritis, hepatitis B and C, HIV-associated arthropathy, SBE with arthritis and serum sickness reactions.
Hyperthyroidism can uncommonly cause acropathy (clubbing and swelling of the fingers) and may present as pseudogout, while hypothyroidism can present with an arthropathy or cause proximal muscle pain, stiffness and weakness. Diabetes mellitus may cause an arthropathy that can be painless or mild to moderately painful.
The spondyloarthropathies may be a causative factor. They often present with an acute monoarthritis, particularly in teenagers, some time before causing sacroiliitis and spondylitis.
Although ‘arthralgia’ is an uncommon complaint in psychoneurotic disorders, any pain syndrome can be a significant manifestation. The usual cause of arthralgia is inflammation in the joint—that is, arthritis—but a functional cause is encountered from time to time.
Furthermore, some patients who are unfortunate enough to acquire arthritis, especially the more serious disorders, certainly develop ongoing emotional and psychological problems that appear to aggravate their total problem.
So-called ‘growing pains’ of the lower limb are common in children, and the physical examination and investigations are normal. Parents need to be reassured that it is a benign condition, while recognising that emotional factors may be quite significant. As Apley pointed out, ‘physical growth is not painful, but emotional growth can hurt like hell’.5