The Musculoskeletal System | Approach to the patient with complaints
Disorders of the musculoskeletal system make up 20–25 per cent of a general practitioner’s workload and account for significant disability in the general population. The symptoms and signs range from focal to widespread and can be associated with a number of systemic pathologies typically affecting the skin, eyes, lungs, kidneys, bowel, endocrine and nervous systems. These disorders are primarily the realm of the rheumatologist, orthopaedic surgeon, neurologist, and pain specialist; equally many disorders may present to allied healthcare professionals such as physiotherapists, osteopaths and chiropractors dealing with musculoskeletal pain and dysfunction.
It is common to find that musculoskeletal assessment is either omitted in medical notes or the term ‘arthritis’ or ‘rheumatism’ appears in the history without further elaboration. Rather than becoming overwhelmed with making a diagnosis from over 200 forms of ‘arthritis’, it is clinically more useful to describe the distribution and nature of the symptoms and signs, together with the impact on function, and be able to undertake a focused history and examination of other systems when a systemic disorder is suspected.
At the end of the history taking you should be able to determine:
- whether the condition is most likely mechanical or inflammatory
- whether it is acute or chronic, and persistent or intermittent
- the distribution of joints/soft tissues/nerves/muscles involved
- functional and psychosocial impact
- treatments tried and their effectiveness
- presence of associated end-organ/systemic pathology.
The chief symptoms to identify in the musculoskeletal assessment are:
- impaired function
Record the site, radiation, nature and relieving and aggravating factors.
Site and radiation
It may be possible to localize pain to specific sites. Pain may be focal (e.g. along a bone, tendon, or muscle), or it may be diffuse over or within a joint. Pain may radiate giving symptoms away from the site of the pathology. For example:
- a trapped nerve due to mechanical damage of vertebral bodies (cervical or lumbar spondylosis) or a prolapsed disc may cause pain along the nerve affected; in sciatica pain may be felt from the buttock down the outside of the leg to the foot. Nerve entrapment in the neck may be felt in the shoulder and hand
- hip pain (normally felt in the groin) may radiate to the knee and vice versa.
The ability to describe which joints are involved is fundamental. First, classify the condition according to whether it is:
- monoarticular – one joint involved
- pauciarticular – up to four joints involved
- polyarticular – more than four joints involved
- axial – affecting the spine.
Second, consider the symmetry and distribution. Symmetry (involvement of the same joints on either side of the body) is typical of the inflammatory autoimmune rheumatic diseases (ARDs) (Table 14.1). Look for common patterns.
- In rheumatoid arthritis (RA) the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints are usually symmetrically involved with sparing of the distal interphalangeal (DIP) joints.
- Asymmetry is more typical of conditions such as osteoarthritis (OA), gout, and psoriatic arthritis (PsA); the PIP and DIP joints are often involved.
- Axial disease affecting the spine and sacroiliac joints is typical of ankylosing spondylitis (AS).
Chronic widespread pain (CWP) – generalized pain for more than 3 months – is common. Up to 10 per cent of the general population describes having CWP. It may be a consequence of:
- multiple joint problems or a myopathy
- fibromyalgia – multiple tender points in muscles and tendon insertions
- joint hypermobility syndrome
- polymyalgia rheumatica – pain in the shoulder girdle (neck, shoulder, upper arm) and/or pelvic girdle (lower back, hips and thighs).
Pain is described in many different ways. Given its variability, a description of the pain may be of limited value. It is more helpful to understand the patient’s loss of function as a consequence. However, some characteristics are important:
- paraesthesia or weakness in the distribution of a nerve root, e.g. nerve entrapment or inflammation (mononeuritis)
- focal, constant pain, waking the patient. This may be a bone lesion such as a malignancy or infection
- sudden acute pain in the absence of trauma. In the spine this may be an acute vertebral fracture, perhaps from osteoporosis or malignancy. It may be a sign of an inflamed disc. In a large joint think about a cartilage tear, septic arthritis, spontaneous haemarthrosis or tendon rupture.
Relieving and aggravating factors
As a rule mechanical disorders (e.g. OA, spondylosis, and tendinopathies) are worsened by activity and relieved by rest. In severe degenerative disease the pain may, however, be present at rest and disturb sleep. Inflammatory disorders tend to be painful both at rest and during activity and are associated with worsened stiffness after periods of prolonged rest. The patient may note that stiffness is relieved somewhat by movement. Both mechanical and inflammatory disorders may be worsened by excessive movement.
Some patients can identify relieving factors such as hot/cold compress, straps/support, acupuncture, massage and physiotherapy, etc. It is helpful to know what relieves their pain and to what degree.
The majority of patients will have taken pain killers. Find out:
- which ones they have taken – know your pharmacology; patients may have tried non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, opioids, neuroleptic agents, anti-depressant agents, or topical gels/creams
- why did the patient stop taking the painkiller? Did it not work at all? Were there side effects and if so what? Were they worried about becoming dependent on a drug and therefore didn’t take it?
Before abandoning analgesia as unhelpful find out:
- the frequency and maximum dose tried
- whether there was any relief that then wore off.
A number of patients say their painkiller did not work but on further questioning it may become clear that either they did not take enough, frequently enough, or the drug worked for a few hours and then wore off. Converting the painkiller to a long-acting slow-release formula may reduce the ‘on–off ’ effect; one example is the use of a 12-hour slow release formula in the evening giving relief of early morning stiffness and pain.
A patient may not be able to differentiate ‘stiffness’ from pain and swelling. Difficulty moving a joint may be a combination of all three symptoms. However, many patients will recognize the phenomenon of worsened joint stiffness after a period of rest. Prolonged stiffness is associated with inflammatory arthritis; typically it lasts 1–2 hours and eases with heat and movement. The duration may be a guide to inflammatory disease activity.
Short periods of generalized stiffness (up to 30 minutes) are not meaningful. Localized joint stiffness of short duration may be a feature of mechanical disorders. These short episodes tend to be intermittent and occur throughout the day after any period of rest.
Stiffness may also occur in a normal joint. Some people ‘crack’ or ‘click’ their joints to relieve themselves of the symptom. This and the clicking are usually benign and not associated with long-term risk of joint damage. If however a clicking joint or tendon also hurts at the time of the click this would suggest a mechanical problem that needs assessment.
Finally, stiffness may be the result of a tendon nodule or fibrosis. At its extreme the tendon mechanism may get stuck; this is termed ‘triggering’ and is most often seen in the flexor tendons of the fingers.
Joint swelling is indicative of an inflammatory condition, infection (septic arthritis) or trauma and may be due to soft tissue inflammation, thickening of the synovial membrane or an excess of synovial fluid causing an effusion.
Consider the possibility that swelling may be a consequence of peripheral oedema, cellulitis, deep vein thrombosis or varicose veins. Trauma may lead to the rapid development of an effusion. This may be synovial fluid or blood (haemarthrosis). Occasionally, and in the absence of trauma, an effusion may be very rapid in onset and so painful that the patient cannot move the joint. In these circumstances a septic arthritis should be considered.
Swelling does not always imply the presence of an inflammatory arthritis. In particular swelling can often be seen in OA; in the hands this is usually due to bone nodules. Occasionally in OA cartilage debris and calcium crystals within the joint may induce an effusion. Typical joints affected in this way include the knee, hips and shoulder.
Difficulty with specific movements may occur as a consequence of pain, tissue damage, fibrosis (contractures), fusion (bone ankylosis), or neuropathy. Functional impairment may have a profound impact on mood and sleep leading to anxiety, depression, and fatigue.
Every patient is different in their perception of the problem, coping strategies for activities of daily living (hygiene, cooking, and dressing), and integration (relationships and sexual activity, social interactions, work, and exercise). Take a social and treatment history to identify the impact on these aspects of well-being. As well as use of medications, identify coping strategies and modifications to the environment that support activity, e.g. occupational therapy advice and home adjustments (hand rails, gadgets, downstairs wash facilities, ramps instead of steps, etc.).
Patients with arthritis may describe symptoms of fatigue, fever, sweating and weight loss. A number of other diseases and disorders may manifest as or have complications of a musculoskeletal origin. Table 14.1 describes some of the ‘extra-articular manifestations’ or associations seen in arthritic conditions (although the list is not exhaustive).
At the end of a ‘screening’ inspection of the musculoskeletal system it should be possible to identify which sites are affected and to what degree. A more detailed examination of the sites involved is then required. There are four parts to the physical assessment: inspection, palpation, movement and function.
Look for swelling, deformities, nodules, asymmetry, muscle wasting, scars, skin pathology (Table 14.2, Figs 14.1–14.3).
Perform the gait, arms, legs, spine screen (Doherty et al., 1992). This is a rapid screening of joint movement designed to identify affected areas (Table 14.3, p. 240, Fig. 14.4).
Be gentle, avoiding excessive pressure or sudden movement that may cause unnecessary pain. If a joint, muscle, or tendon is swollen, painful, or there is a reduced range of movement then feel for warmth of inflammation using the back of the fingers. Gently squeeze individual joints and palpate soft tissues for tenderness.
Ask whether any areas of the body are numb or weak and be prepared to perform a sensory or motor neurological examination, respectively, after the screening assessment.
Regional examination of the musculoskeletal sys-tem (Coady et al., 2004) is beyond the scope of this chapter. For now, focus on being able to perform the screen, but we would encourage you to learn regional examination during the course of an attachment to a musculoskeletal firm and to read the Arthritis research campaign handbook and DVD giving a detailed demonstration of joint and soft tissue examination (Coady, 2005).
At any one site, there are three assessments of movement:
- Active movement – the patient doing it themselves
- Active movement against a resisting force – the patient holds a position while the assessor places a gentle force against it. If pain is induced it may ndicate tendon pathology
- Passive movement – the assessor moves the joint. This may be necessary if a patient cannot move because of weakness or pain. Always perform passive movement slowly and gently in order to ascertain the extent of range of movement without causing undue pain. Full range on passive movement but limited or no range on active movement suggests the problem is neurological or muscle/tendon rather than articular.
Range of movement on each side of the body should be compared. Look for excessive movement (hypermobility). Note a painful hypermobile joint may still move in what seems to be a normal range for the general population.
Loss of movement leads to loss of function. Patients often learn to compensate. Consider what the joint does thus focusing attention on what the issues might be. For example:
- unable to rotate the shoulder to place hand behind back – how does this person manage washing, or doing up a brassiere?
- cannot bend knee – how do they sit or climb stairs?
Regional examination of the hips and knees
- Ask the patient to lie on the couch after completing the general screen. Perform the log-rolling test of the hips by placing the legs in extension and gently rolling the entire limb back and forth looking for pain in the groin and limitation of internal or external rotation, comparing left and right sides.
- Thomas’ test is used to identify hip flexion deformity. It is only useful if there is no flexion deformity of the ipsilateral knee. With the patient lying flat, fully flex the opposite hip and knee; this flattens lumbar lordosis. Look at the knee on the involved side. It should remain flat on the couch. If it is now elevated off the couch and cannot be flattened there is an ipsilateral hip flexion deformity present that may be due to arthritis or tight hip flexors.
- Assess the knee for an effusion by eliciting the bulge sign and ballotting the patella.
- The bulge sign test is helpful in identifying a small effusion. It is performed with the knee fully extended and the muscles relaxed. Displace the effusion by stroking the thumb down the medial side of the knee below the patella margin. This creates a recess or dimple and the lateral side of the knee may fill. Now stroke the lateral side of the knee and observe the medial recess refill.
- Ballottement is useful if a large knee effusion is present. In the same position as above, use the index finger to push the patella straight down. Release quickly and repeat the motion. In the presence of an effusion you can feel the patella knocking against the femur below.
INVESTIGATING MUSCULOSKELETAL DISORDERS
Having identified the distribution, symmetry, and possible associated extra-articular manifestations of disease, it should now be possible to determine whether the condition is regional or generalized, and mechanical or inflammatory. Laboratory and radiological investigations are used to support a diagnosis, assess severity, and may be of prognostic value.
Screening tests for inflammation and autoimmune rheumatic diseases
- Erythrocyte sedimentation rate (ESR).
- C-reactive protein (CRP): unlike the ESR, it is unaffected by anaemia or hyperglobulinaemia, both of which may be present in ARDs.
- Full blood count: anaemia of chronic disease, leucopenia, lymphopenia, and thrombocytopenia may be present in ARDs. Though they may be directly associated with disease, they may be the consequence of drug therapies, in particular disease modifying anti-rheumatic drugs (DMARDS) such as methotrexate and azathioprine, and biological therapies. NSAIDs, by inducing peptic ulcer disease and gastrointestinal blood loss, might cause anaemia.
- Urea and electrolytes, and serum uric acid: renal impairment may be a manifestation of an ARD. Equally it may be a result of drug treatment (e.g. NSAIDs, ciclosporin), or other co-morbidity e.g. diabetes or hypertension. Chronic renal impairment may result in high serum uric acid levels and low vitamin D levels, leading to gout and osteomalacia respectively.
- Urinalysis: protein and blood in the urine may indicate glomerulonephritis or infection. Detailed microscopy for inflammatory casts and culture is warranted.
- Liver function tests: abnormalities may be drug-induced or a manifestation of autoimmune hepatitis. Infections such as hepatitis B and C are also associated with inflammatory arthritis. Note that a raised alkaline phosphatase (ALP) might be from bone and alanine transferase (ALT) from muscle rather than liver.
- There are many causes for a raised creatine kinase (CK). In the context of diffuse muscle pain (myalgia) and inflammation a raised CK suggests myositis.
- Rheumatoid factor (RF) is of value in establishing the diagnosis of RA. However, up to 5 per cent of the population may be positive for RF with no consequence. Equally, only 70–80 per cent of patients with RA are RF positive.
- Rheumatoid factor may be positive in other rheumatic diseases such as Sjögren’s syndrome and SLE, chronic infections such as subacute bacterial endocarditis and hepatitis C, and chronic lung and liver disease.
- Anticyclic citrullinated peptide (anti-CCP) antibody is a marker for diagnosis and prognosis in RA. Anti-CCP antibody is detected in 50–60 per cent of patients with early RA. It is a marker of erosive disease and predicts development of RA in patients with non-specific inflammatory symptoms. The test is therefore valuable when the history suggests RA but the clinical signs are minimal and the RF is low or negative.
- Anti-nuclear antibody (ANA) is often positive in the ARDs (Table 14.1). Over 95 per cent of patients with SLE have a positive ANA. The test, however, is not specific and may be positive in other end-organ diseases such as thyroiditis and hepatitis.
Screening tests for focal bone pain or diffuse myalgia and fatigue
- Check for an abnormal ESR, CRP, and FBC that might suggest the presence of a malignancy.
- A raised calcium suggests either hyperparathyroidism, malignancy involving bone, or sarcoidosis.
- Focal bone pain with a raised ALP but normal calcium may suggest Paget’s disease, a bone cyst or tumour, fracture or osteomalacia.
- Diffuse myalgia may be due to polymyalgia rheumatica (raised ESR but normal CK), polymyositis (raised ESR and CK), endocrinopathies (hypo- and hyperthyroidism) or vitamin D deficiency.
- Laboratory investigations should be normal in CWP due to fibromyalgia and joint hypermobility syndrome.
Other specific laboratory tests
- Extractable nuclear antigens (ENA) are helpful in separating out the ARDs and identifying risk for specific pathologies such as renal disease. The common ENAs are:
- anti-Ro and anti-La – found in Sjögren’s syndrome, SLE, and RA
- anti-SM and RNP – found in SLE
- anti-centromere and Scl-70 – in systemic sclerosis
- anti-Jo-1 – in polymyositis.
- Antiphospholipid and anticardiolipin antibodies are associated with arterial and venous thrombosis, spontaneous abortion, and acute cerebral vasculopathy. They are found primarily in antiphospholipid syndrome and SLE.
- Antineutrophil cytoplasmic antibody (ANCA); cANCA and pANCA are associated with the vasculitides (Table 14.1).
- Infections: tests to consider include blood cultures, synovial fluid culture if there is an effusion, antistreptolysin O titre (ASO titre), hepatitis B and C serology, parvovirus B19 IgG and IgM, and a human immunodeficiency virus (HIV) test.
Plain radiographs are a simple and helpful tool (Fig. 14.5). Radiological changes due to inflammatory conditions such as RA, gout and psoriatic arthropathy include:
- soft tissue swelling
- periarticular bone demineralization
- diffuse loss of joint space
- erosions – seen at the far margins of the joint where the cartilage no longer covers bone
- gross joint destruction in advanced erosive disease. This may lead to joint dislocation, subluxation, or ankylosis (fusion of the joint surfaces).
Mechanical or degenerative conditions such as OA manifest radiologically as:
- bony nodules – osteophytes at joint margins G bone cysts along the joint line
- sclerosis along the joint line
- focal or diffuse loss of joint space
- chondrocalcinosis – pyrophosphate crystal deposition in the fibrocartilage
- loose bodies – bone debris in the joint space.
Other imaging techniques include the following.
- Ultrasound – this can assess soft tissue injuries, including the deep tendon structures, and is an aid to local corticosteroid injections. Ultrasound can also be used to identify early erosions.
- Isotope bone scanning – this is valuable in identifying areas of high bone turnover. Isotope uptake is increased at sites of bone metastases, fractures, Paget’s disease, infection (osteomyelitis), and inflammation (e.g. sacroiliac joints in AS).
- Magnetic resonance imaging (MRI) – this provides highly detailed information on the anatomy and pathology of soft tissues and joints. It is particularly valuable in assessing the presence of erosions in the hands and feet, inflammatory and mechanical disorders of the spine and spinal cord, and tendon, ligament, and cartilage abnormalities of the shoulder, hip, and knee.
COMMON MUSCULOSKELETAL DIAGNOSES
About 10 percent of the adult population experiences neck pain at any one time, although many people do not seek medical help. About 1 percent of adults with neck pain develop neurological deficits. Most neck pain occurs at the level of C5–C6 and is mechanical in nature due to disc degeneration.
Nerve root (radicular) pain is usually sharp with paraesthesia radiating into the arms or hands. Common causes for radicular pain are compression by an intervertebral disc or an osteophyte encroaching on the nerve root exit foramen.
Indicators of serious pathology in lumbar pain: ‘red flags’ of serious pathology that requires further investigation with blood tests and plain radiographs are:
- presenting under age 20 and over age 55 years
- prolonged stiffness (> 6 weeks)
- sudden onset of severe pain
- pain that disturbs sleep (> 6 weeks)
- thoracic pain
- nerve root symptoms – including spinal claudication (pain on walking resolved by rest), saddle numbness, and loss of bladder or bowel control
- chronic persistent pain (> 12 weeks)
- weight loss
- history of carcinoma
The lifetime incidence of lower back pain is about 60 per cent and the greatest prevalence is between ages 45 and 65 years. Over 90 per cent of low back pain is mechanical and self-limiting. Low back pain can arise from disc degeneration (spondylosis) or inflammation of the thoracic or lumbar spine and sacroiliac joints. Pain may be referred from the retro-peritoneum or pelvic viscera, e.g. renal pain.
It is important to ensure there is no evidence of a vertebral fracture, bone metastases, sequestered prolapsed disc, discitis, infection, or onset of an inflammatory condition such as AS. Vertebral fractures appear on radiographs as either flattening of the whole vertebra (‘compression’ fracture) or, more commonly, with loss of height on the anterior border of the vertebra (‘wedge’ fracture).
A motor and sensory neurological examination of the arms and legs is essential in suspected cases of nerve root entrapment, cord compression, or spinal stenosis at the neck. Similarly an examination of the legs is essential if pathology is suspected in the lower spine.
The management options for chronic low back pain due to degenerative disease and in the absence of serious pathology include:
- exercise advice
- transcutaneous nerve stimulation (TENS)
- ‘back schools’ – education.
Chronic widespread pain
Chronic widespread pain is present in 5–10 per cent of the general population. In the absence of diffuse degenerative or inflammatory rheumatic disease the two most common conditions found in association with CWP are fibromyalgia and joint hypermobility syndrome.
In addition to diffuse tenderness at discrete anatomical sites patients with fibromyalgia experience a range of symptoms including fatigue, mood and sleep disturbance. Fibromyalgia is also found in up to 25 per cent of patients with RA, AS, SLE, and joint hypermobility syndrome. Fibromyalgia and joint hypermobility syndrome also overlap symptomatically with chronic fatigue syndrome in many ways. Care must therefore be taken to avoid misdiagnosing fibromyalgia as the only cause for pain. If joint hypermobility syndrome is suspected, look for generalized hypermobility, particularly in the fingers, elbows, lumbar spine, knees, and feet (flat feet), easy scarring and bruising, and evidence of soft tissue elasticity, such as hernias and pelvic floor prolapse. Other metabolic causes of fatigue should always be excluded, e.g. hypothyroidism, hypoadrenalism, hypo/hyperglycaemia, and anaemia.
Fibromyalgia is considered when all of the following are present:
- pain in the left and right side of the body
- pain above and below the waist
- axial skeletal pain
- pain present for at least 3 months.
Tenderness should be elicited over 11 or more of 18 sites (Fig. 14.6) by palpation using the thumb with a pressure sufficient to make the nail blanch. The nine sites (repeated each side) are:
- occiput at the paraspinal muscle insertions of the neck
- lower cervical spine at the inter-transverse spaces at the level C6–7
- trapezius, mid-way along the upper border
- origin of supraspinatus, just above the spine of the scapula at its medial border
- second rib at the costochondral junction
- lateral humeral epicondyle, 2cm distal from the epicondyles
- lower lumbar spine
- gluteal, in the upper inner quadrant
- knee, medial fat pad proximal to the joint line.
The emphasis in management is an explanation and reassurance that there is no serious underlying inflammatory/systemic condition or damage to the joints and muscles. Although exercise may cause a short-term increase in pain, a prolonged aerobic exercise programme may help. Pacing daily activities is also important, avoiding patterns of overactivity when well, followed by inactivity due to pain and fatigue. Pacing is a key component of cognitive behavioural therapy, a chronic pain programme that, alongside aerobic rehabilitation, may be of significant benefit to patients with fibromyalgia, CWP and joint hypermobility syndrome. NSAIDs and opioid analgesics usually do not work. Tricyclic antidepressants (such as amitriptyline) and neuroleptic agents (such as gabapentin and pregabalin) may be helpful.
Osteoarthritis is a chronic degenerative and mechanical disorder characterized by cartilage loss. It is the most common form of arthritis, estimated to affect 15 per cent of the population of the UK over the age of 55 years. It is second only to cardiovascular disease as a cause of disability. Weight-bearing joints are chiefly involved (e.g. facets in the spine, hip and knee). However, OA can be generalized with a ‘nodal’ form that typically affects the PIP and DIP joints of the hands (Fig. 14.7).
Risk factors for OA that should be considered in the history include:
- family history (particularly the ‘nodal generalized’ form)
- high bone density such as osteopetrosis (‘marble bone syndrome’)
- fractures through the joint line
- abnormal bone/joint formation – dysplasias
- neurological or muscular disease leading to weakness and abnormal mechanical forces on a joint.
OA is a clinical and radiological diagnosis. There are no specific laboratory tests. Plain radiographs classically show joint space narrowing, osteophytes, subchondral sclerosis and bone cysts (see Fig. 14.5).
There is little evidence to link OA with repetitive injury from occupation, except perhaps knee bending in men. Dockers and miners have a higher incidence of knee OA.
Interventions for OA include exercise to build muscle strength, encourage weight loss, and improve endurance and joint proprioception (position sense). NSAIDs, paracetamol and opioid analgesics are effective. Intra-articular injections of long-acting anaesthetic may help pain. Occasionally an OA joint may be inflamed due to debris in the joint; here corticosteroid joint injections are useful. Intra-articular injection of hyaluronic acid derivatives (viscosupplementation) may also reduce pain and swelling for 2–6 months in mild-moderate cases. Glucosamine and chondroitin sulphate supplements may have an analgesic effect in mild-moderate OA of the knee; there is little evidence for their use in OA at other sites. There is some evidence that avocado/soya bean supplementation, evening primrose oil, and omega-3 fish oils improve pain. Management should also include ways to reduce the impact of disability. Options include occupational therapy and physiotherapy. Surgery may be required when conservative therapy is unsuccessful.
Although often presented in textbooks showing features of ‘swan neck’ (hyperextension of PIPs and flexion DIPs), ‘boutonniere’ (spindle shaped swelling of the PIPs with a ‘button hole’ protrusion), ulnar deviation of the MCPs, and ‘Z’ deformity of the thumb (hyperextension of the interphalangeal and flexion of the DIP joint) (see Fig. 14.7), these are the appearances of late RA and are seen less and less, given early intervention with DMARDs and the dramatic remission observed with biological therapies.
Rheumatoid arthritis is the most common ARD and is characterized by the presence of a symmetrical destructive polyarthritis with a predisposition for the small joints of the hands, wrists and feet. It is more common in women than men and may present at any age though most often in the third to fourth decade. Criteria for the diagnosis of RA are shown in Table 14.4. It is important to remember that there are a number of ‘extra-articular’ manifestations to the disease (Table 14.5).
Onset is typically insidious and progressive pain, stiffness and symmetrical swelling of small joints occurs. Up to a third of patients may have a subacute onset with symptoms of fatigue, malaise, weight loss, myalgia, morning stiffness and joint pain without overt signs of swelling. A mono- or bilateral arthropathy of the shoulder or wrist may account for up to 30–40 percent of initial presentations, and the knee 5 per cent. Any synovial joint can become involved.
Spontaneous rupture of tendons and ligaments is uncommon, but typically occurs at the wrist, hand and rotator cuff in the shoulder. More often, tenosynovitis (tendon inflammation) and weakening of ligaments lead to joint instability and subluxation.
The management of RA requires a multidisciplinary approach. Details of drug therapy are beyond the scope of this chapter but patients may require a combination of analgesics, DMARDs and sometimes steroids. A proportion of patients do not respond to DMARDs and require biological therapies (antitumour necrosis factor (TNF) a, B cell depletion, or IL-6 inhibition). Regular liaison with physiotherapists, occupational therapists, podiatrists, social services and surgeons is important in managing complex cases.
Ankylosing spondylitis is one of the seronegative inflammatory arthropathies. The ESR or CRP may be raised but the ANA, RF and ENAs are negative. Included in this group of conditions are psoriatic arthritis (PsA), enteropathic arthritis and reactive arthritis. They are characterized by axial involvement of the skeleton with sacroiliitis.
Patients are typically below 40 years of age with a male to female ratio of approximately 3:1. The condition occurs more frequently in Caucasian populations. The criteria for the diagnosis of AS are shown in Box 14.1.
There is often an insidious onset of low back pain and morning stiffness that tends to improve with exercise. Large joints (hips and knees) may be involved and in PsA small joint disease may mimic RA. Patients may also have insertional tendonitis at several sites outside the spine including the Achilles tendon, intercostal muscles, plantar fascia and a dactylitis (sausage-shaped swelling) of the fingers and toes.
- low back pain and stiffness for >6 months improving with exercise but not relieved by rest
- limitation of lumbar spine movements in lateral and forward flexion
- limitation of chest expansion relative to normal values for age and sex.
- greater than or equal to Grade II bilateral sacroiliitis
- grade III or IV unilateral sacroiliitis
Combined diagnostic criteria
- definite AS if one radiological and one clinical criteria
- probable AS if three clinical criteria or a radiological criterion without signs or symptoms satisfying the clinical criteria.
Later in the disease the spine may become fused with a loss of lumbar lordosis and an increase in thoracic kyphosis – the so-called ‘question-mark’ posture. In order to be able to look ahead the AS patient adopts a hyperextension at the neck, increasing cervical lordosis.
The extra-articular manifestations in AS include:
- constitutional features of fatigue, weight loss, low-grade fever, and anaemia
- iritis – this occurs in up to 40 per cent of cases but has little correlation with disease activity in the spine
- upper lobe or bilateral pulmonary fibrosis. Pleuritis can occur as a consequence of insertional tendonitis of the costosternal and costovertebral muscles. Fusion of the thoracic wall leads to rigidity and reduction in chest expansion
- aortic valve prolapse.
Radiological evaluation is the most helpful form of investigation. The classical findings include sacro-iliac joint sclerosis and erosions, syndesmophytes (calcific thickening of spinal ligaments) and squaring of vertebrae. Isotope bone scanning can highlight inflammation at the sacroiliac joints. MRI may show joint erosions, and oedema and fatty change in the bone marrow induced by inflammation.
General principles for therapy include:
- patient education
- exercise, physiotherapy and hydrotherapy G avoid smoking
- anti-TNF α therapy.
Psoriasis affects 1–2 per cent of the population and 10 per cent of these develop arthritis. Psoriatic arthritis may affect any peripheral joint as well as the axial skeleton and sacroiliac joints. Nail lesions occur in up to 90 per cent of patients with PsA. These lesions include pitting, ridging, and onycholysis (see Fig. 14.7).
There are five clinical patterns of psoriatic arthritis:
- distal, involving the distal interphalangeal joints G asymmetrical oligoarthritis
- symmetrical polyarthritis, indistinguishable from RA
- arthritis mutilans
The radiological features associated with PsA that help to differentiate it from RA include:
- DIP joint disease
- osteolysis of terminal phalanges with ‘pencil-in-cup’ deformities
- cervical and lumbar spondylitis
- periostitis (inflammation of periosteum).
Also, unlike RA, periarticular osteopenia is uncommon. The treatment of PsA is like that of RA with NSAIDs, DMARDs (particularly methotrexate and leflunomide), and biological therapies. Systemic corticosteroids should be avoided as they may worsen the skin disease. Intra-articular steroids may be helpful.
Gout and hyperuricaemia
Gout is a group of conditions characterized by hyperuricaemia and uric acid crystal deposition in the joints, skin and renal tract leading to an inflammatory arthritis, tophaceous gout, nephrolithiasis and nephropathy respectively. Table 14.6 outlines the risk factors for developing gout.
The condition is more common in men than women and tends to occur from the fourth decade on. The most common symptom is an acute, self-limiting, monoarthritis; up to 60–70 per cent of attacks first occur in the big toe. Other frequently involved joints include the ankle, foot, knee, wrist, elbow (olecranon bursa), and the small joints of the hands. Gout can mimic RA and septic arthritis.
Tophi are subcutaneous deposits of urate. The classic sites are the pinna of the ear, bursa of the elbow and knee, Achilles tendon, and the dorsal surface of the small joints of the hands (see Fig. 14.7). Tophi are usually painless, though the overlying skin may ulcerate and become infected. Those most at risk of tophi are patients with prolonged severe hyperuricaemia, polyarticular gout, and elderly patients with primary nodal OA who are on diuretics.
Synovial fluid analysis should be undertaken, looking for negatively birefringent needle shaped crystals with polarized light microscopy; the absence of crystals, however, does not rule out the diagnosis. The serum uric acid level may be normal during an acute attack. Uric acid levels are nevertheless of value when monitoring the effectiveness of therapies that lower serum urate. Late features on radiographs may be tophi near joints, tissue swelling, joint erosions, periosteal new bone formation, and joint deformity.
Public health improvement measures to prevent gout are yet to be proven. However avoiding excess weight gain and alcohol, controlling hypertension, and exposure to diuretics, may have some effect on reducing risk of gout. Otherwise, there are two phases to therapy: treatment of the acute attack, and treatment of chronic disease. Acute attacks should be managed with a combination of NSAIDs, colchicine and corticosteroids. In the longer term, agents that reduce serum urate should be used, the most common of these being allopurinol.
This remains a significant cause of morbidity and mortality. Peak bone mass is usually achieved in the third decade and is determined by both genetic and environmental factors. After the age of 35 the amount of bone laid down is less than that reabsorbed during each remodelling cycle. The net effect is age-related loss of bone mass. Up to 15 per cent of bone mass can also be lost over the 5-year period immediately post menopause. Symptomless reduction in bone mass and strength results in an increased risk of fracture; it is the resulting fractures that lead to pain and morbidity.
Major risk factors to be considered in osteoporosis are:
- race (white or Asian > African Caribbean) G age
- family history of maternal hip fracture
- previous low trauma fracture (low trauma defined as no greater than falling from standing height)
- long-term use of corticosteroids
- malabsorption disorders
- endocrinopathies – hyperparathyroidism, hyperthyroidism, low vitamin D
- inflammatory arthritis e.g. RA, AS, SLE.
Other risk factors include:
- low body mass index (BMI <16 kg/m2) G late menarche and early menopause
- reduced physical activity
- low intake of calcium (below 240 mg daily) G excess alcohol intake
- malignancy (multiple myeloma).
Plain radiographs are insensitive for assessing bone mass. The standard technique for measuring bone mineral density (BMD) is dual energy X-ray absorptiometry (DEXA). This gives two readings, the ‘T’ and ‘Z’ scores:
- ‘T’ score is the individual’s bone mineral density compared with the mean bone mineral density achieved at peak bone mass (i.e. around age 35) for the same sex and race. Most analyses and studies have focused on the T score
- ‘Z’ score is the individual’s bone mineral density compared with that for someone of the same age, sex and race.
One standard deviation below the mean is equal to a twofold increase in the risk of fracture. This means that an individual with a BMD three standard deviations below the mean has an eightfold increased risk of fracture, compared with a ‘normal’ individual of the same age.
Calcium, phosphate and ALP levels are normal in osteoporosis. Investigation should include a screen for malignancy and biochemical abnormalities of bone (i.e. ESR, urea and electrolytes, liver function test, serum immunoglobulins, calcium and phosphate).
Management focuses on reducing the risks, falls assessment, and adequate daily calcium (1g) and vitamin D (800IU) intake. Specific therapies such as bisphosphonates and strontium ranelate may prevent further bone loss and reduce fracture risk after the menopause.
Osteomalacia results either from deficiency of vitamin D (poor intake, lack of sunlight exposure, malabsorption, liver or renal disease) or rare abnormalities of phosphate metabolism (renal tubular acidosis, hypophosphatasia).
A decrease in the ratio of mineral to matrix leads to softening of bone. Symptoms include bone pain, bone deformity, fractures, and proximal muscle weakness with a ‘waddling gait’. Plasma levels of calcium and phosphate are usually reduced and ALP raised. Hypocalcaemia may give rise to paraesthesia and tetany; rarely, it can cause cardiac dysrhythmia, convulsions, or psychosis.
The classical radiographic change is the pseudofracture (Looser’s zone), found most often at the ribs and clavicles, outer border of the scapulae, pubic rami, femoral neck, and metatarsals. They appear as incomplete, radiolucent fracture lines perpendicular to the cortex, with poor callus formation.
Management requires treatment of the underlying cause and adequate vitamin D replacement. Many bony deformities persist despite treatment (unless due to simple dietary deficiency and treated in childhood) and may require surgery, e.g. tibial/ fibular osteotomy to correct lower limb alignment.
Infection and arthritis
Infection may give rise to systemic inflammatory arthritis or vasculitis. The condition ‘reactive arthritis’ is also recognized. The disorder is characterized by conjunctivitis, urethritis or colitis, skin lesions in the palms and soles, and either a pauci- or polyarthritis. It is usually triggered by sexually transmitted infection such as with Chlamydia trachomatis. The acute inflammatory reaction is treated with NSAIDs and corticosteroids and often ‘burns out’ after 6–18 months. It may leave lasting joint damage.
Septic arthritis is an acute mono- or pauci-articular pathology. Staphylococcal, gonococcal, pneumococcal, Escherichia coli, and Mycobacterium tuberculosis infection are among the more common causes. Diagnosis is made by culture of synovial fluid and treatment involves high dose antimicrobial therapy for up to 6 weeks (or 9 months if tuberculosis).
Septic arthritis constitutes an acute emergency. The presentation is usually one of a rapid onset of severe pain in a hot swollen joint, the pain so severe that the patient cannot bear for it to be touched or moved.
Neoplasia and bone pain
Focal pain, swelling, or a low trauma fracture in the spine or long bones should alert suspicion. Primary tumours of bone include the benign (but often very painful) osteoid-osteoma, chondromas, and malignant osteosarcoma. Metastatic carcinoma may be secondary to a primary lesion in the lung, breast, prostate, kidney or thyroid. Haematological malignancies including lymphomas and leukaemias may also lead to diffuse bone involvement. Multiple myeloma, a neoplasia of plasma cells, is an important example; it is associated with widespread bone destruction, hypercalcaemia, and renal impairment.
Key features of the presenting history are:
- site and radiation
- relieving and aggravating factors
- impaired function
- constitutional symptoms.
Include the following in your physical examination:
- muscle wasting G scars
- skin pathology
- perform the gait, arms, legs, spine screen
- feel for warmth of inflammation
- gently squeeze individual joints and palpate soft tissues for tenderness
- ask whether any areas of the body are numb or weak – be prepared to perform a sensory or motor neurological examination
- active movement
- active movement against a resisting force
- passive movement
- compare range of movement on each side of the body
- look for excessive movement (hypermobility)
- loss of movement leads to loss of function
- consider what the joint does
- regional examination of the hips and knees:
- log-rolling test of the hips
- Thomas’ test to identify hip flexion deformity
- assess the knee for an effusion: bulge sign test; ballottement.
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