Abstract
Joint pain makes up a significant proportion of presentations to general practice. Causes range from minor mechanical issues to serious conditions such as septic arthritis. Clues from the history such as onset, progression, and extra-articular symptoms aid diagnosis. Many cases of joint pain are appropriately investigated and managed in general practice, but some presentations require referral to secondary care, such as those with signs or symptoms of inflammatory arthritis. It is crucial that red flags for serious or life-threatening causes of joint pain are identified and acted upon urgently.
Clinical case scenario
Joseph, a 38-year-old mechanic, attends your surgery complaining of progressively worsening pain in multiple joints for the past 6 weeks. He has had to take several days off work from his manual job. This in turn is affecting his mental health, as it is causing financial worries. Joseph reports pain in his hands, wrists, shoulders, and knees bilaterally, which is worse first thing in the morning. He finds it difficult to get up in the morning, as he feels very stiff and finds it can take an hour or so before the stiffness eases. He has noticed that some of his finger joints appear swollen and red. He has no significant family history and up until now has been fit and well, with no regular medication. He has no idea what is causing his symptoms.
Background
Joint pain is responsible for approximately 21% of GP presentations, with 28.9% of the UK population thought to be living with a musculoskeletal (MSK) condition (Keavy, 2020). MSK conditions are a common cause of repeated consultations (Margham, 2011). Joint pains can affect patients of any age and may present in a variety of ways depending on the cause. The commonest MSK presentations to primary care are low back pain and knee pain (Keavy, 2020). There are over 120 different rheumatic or MSK diagnoses (West, 2015), including both acute and chronic conditions. Joint pain can cause significant functional impact, as well as psychological distress.
Joint pain history
Pathophysiology
There are many potential underlying causes for joint pain, which can make assessing joint pain daunting. The commonest presentations to general practice fall into three main categories: traumatic (e.g. soft tissue injuries), degenerative (e.g. osteoarthritis (OA)) and inflammatory/autoimmune (e.g. rheumatoid arthritis (RA)). There are rarer causes that should be borne in mind. For example, back pain is most commonly caused by muscular issues or poor posture, but other more serious causes, such as scoliosis, or ankylosing spondylitis must not be overlooked. Back pain is also a potential presenting symptom of bony metastases, as well as urological, gastroenterological, gynaecological, and vascular problems.
Demographics
Patient demographics may point to particular diagnoses, for example, OA is more likely to present in older overweight people, whereas sportspeople are more likely to present with soft tissue injuries such as meniscal injuries and tendinopathy. Inflammatory arthritis may present at any age, sometimes with a trigger, such as an infection or drug reaction, or may occur as part of a systemic autoimmune condition, such as systemic lupus erythematosus (SLE). The commonest form of inflammatory arthritis is RA, which affects around 400 000 adults over 16 years of age in the UK. It is most likely to present between the ages of 40 and 60 years and affects more women than men.
Timeline
The timeline of symptoms can provide clues to diagnosis, for example, whether the problem is acute or chronic, fluctuating or progressive, episodic or continuous. In some cases, there may be an obvious trigger, such as injury, overuse, infection or drug reaction. Degenerative joint conditions such as OA tend to be slowly progressive, but may have acute flare ups, particularly if the patient has been over-using the joint. They may be exacerbated by exercise and weight gain. Inflammatory conditions tend to present with a more rapid onset. A key feature of inflammatory arthritis is joint stiffness, which usually occurs in the morning and lasts more than 30 minutes. Morning stiffness will be significant enough that patients find it difficult to get out of bed, walk, and dress themselves. Inflammatory arthritis will tend to improve with exercise in contrast with degenerative arthritis. Table 1 summarises the difference in presentation between inflammatory and mechanical causes of joint pains. Patients with other causes of joint pain may also complain of stiffness, but it will tend to be less severe and long-lasting.
Differing features of inflammatory and mechanical joint pain.
Pattern of joints affected
Polyarthritis is the term used to describe joint pain in multiple joints, as opposed to monoarthritis (one joint) or oligoarthritis (a few joints). Different causes will affect a different distribution of joints. Figure 1 demonstrates the distribution of OA versus RA. OA tends to affect large-weight-bearing joints, such as hips, knees and spine, plus the distal inter-phalangeal joints of the hands and the base of the thumbs. RA is typically symmetrical, with multiple joints affected, typically the proximal inter-phalangeal joints and metacarpal joints of the hands, as well as larger joints such as the wrists, shoulders, and knees. Other seronegative forms of inflammatory arthritis such as psoriatic arthritis and spondyloarthropathy also present with inflammatory symptoms, but tend to affect joints in an asymmetrical pattern and are more likely to affect the spine (West, 2015).
Distribution of affected joints in RA (left) versus OA (right).
The acutely red and hot joint
Gout is a common cause of acutely red and hot joints in adults in the UK, with a prevalence of 2.5% (Russell et al., 2022). It is suggested by a history of sudden onset redness, swelling and exquisite tenderness, reaching maximum intensity within 24 hours. The most commonly affected joint is the first metatarsophalangeal joint, although gout can affect any synovial joint. There may be a history of recurrent episodes. Gouty tophi may form over the extensor tendons in chronic gout. Differential diagnosis of an acutely red, hot joint should include gout, infection, calcium pyrophosphate crystal deposition, and other forms of inflammatory arthritis, such as RA. Gout can usually be diagnosed clinically, although tests may be performed if diagnosis is unclear, e.g. joint aspiration carried out in secondary care in the case of a solitary hot, red joint where septic arthritis cannot be excluded. The National Institute for Health and Care Excellence (NICE, 2022a) suggests using the American College of Rheumatology’s diagnostic criteria (see Box 1).
Diagnosis of gout.
● Positive joint aspiration results (i.e. monosodium urate crystals seen in aspirate) ● Evidence of monosodium urate crystals in tophi ● Or the presence of six or more of the following features: ○ >1 acute attack ○ Reaching maximum intensity within 24 hours ○ Monoarthritis with erythema over the affected joint ○ First metatarsophalangeal joint affected ○ Unilateral attack affecting first metatarsophalangeal joint ○ Unilateral attack affecting a tarsal joint ○ Presence of tophi ○ Raised serum urate levels ○ X-ray findings of symmetrical swelling within a joint ○ X-ray findings of a subcortical cyst without the presence of erosions ○ Negative culture from joint aspirate
Source: NICE (2022a) and based on the American College of Rheumatology (2021) guidance
Red flags
As part of any MSK history, it is important to ask about ‘red flag’ symptoms (summarised in Table 2). These include systemic symptoms such as weight loss, fever, and night pain, which may indicate an underlying systemic condition, infection, or cancer. Septic arthritis is an emergency; any patient presenting with signs of sepsis such as fever, tachycardia or hypotension, or a red, hot joint with limited range of movement should be sent for same-day orthopaedic assessment. Joint aspiration is gold standard for investigation of suspected septic arthritis. Osteomyelitis may also present with joint pain and should be suspected in any patient with deep bone pain with a recent history of injury, wound, or surgery or a weakened immune system. Persistent or severe pain following trauma, however minor, should also prompt consideration of imaging to rule out fracture. Any red flags present should prompt consideration of further urgent investigation.
Extra-articular and red flag symptoms.
Extra-articular symptoms
Inflammatory and autoimmune forms of arthritis are usually multi-system disorders, and therefore, may present with systemic symptoms and/or extra-articular symptoms. Neoplasms, infections, endocrine conditions, metabolic conditions, and drug reactions may all also present with both joint and non-joint symptoms (see Table 2). A systems review is, therefore, an important part of an MSK history. This should include skin and hair, ophthalmic, gastric, cardiovascular, respiratory, neurological, and urinary symptoms. It may also be prudent to check renal function, as renal complications such as glomerulonephritis may occur in many auto-immune conditions, although this should not delay diagnosis. RA with extra-articular symptoms is thought to be associated with worse mortality rates than without, and therefore, the presence or absence of these symptoms may also inform prognosis (Turesson et al., 2003).
Referral of suspected inflammatory arthritis
All patients with suspected inflammatory arthritis should be referred urgently to rheumatology. The NICE quality standard for RA suggests that ‘adults with suspected persistent joint inflammation (synovitis) in more than 1 joint, or the small joints of the hands and feet, should be referred to rheumatology services within 3 working days of presenting in primary care’. This also applies to suspected spondyloarthropathies.
Impacts of chronic joint pain
Functional effect
Joint pains often have a significant functional, social, and psychological impact on patients. This may include an effect on sleep, work, and exercise, as well as the patient’s ability to self-care. This may be caused by joint stiffness, immobility, pain, or fatigue. Patients may lose confidence in their mobility, due to experiencing poor balance or falls. Referral to physio and/or occupational therapy may be helpful.
Psychological aspects of joint pain
There is a complex relationship between pain and mental health. Chronic and acute joint pain can cause psychological distress, particularly when it affects daily activities and sleep. Nazarinasab et al. (2017) found that 58.5% of patients with osteoarthritis had mental health problems, including depression and anxiety. Mental health conditions may exacerbate pain and affect recovery. Somatisation may play a role in disability in both low back pain and knee pain, with the disabling effect of MSK conditions being disproportionate to the physical damage (Fujii et al., 2018). Those with mental health conditions seek medical care more frequently, and may present with joint pain and other medical symptoms rather than psychiatric symptoms (Osterweis et al., 1987), although it should not be assumed that pain is due to mental health without investigating further.
Fibromyalgia
Fibromyalgia syndrome is a chronic condition that is characterised by multiple physical and cognitive symptoms. This includes widespread persistent pain, which may affect multiple areas of the body including muscles and joints, increased sensitivity to pain and other stimuli, excessive fatigue, and brain fog. Anxiety and depression may also be associated with fibromyalgia. The precise cause of fibromyalgia remains poorly understood, but is thought to relate to abnormal processing of pain signals within the nervous system (Wolfe et al, 2016). Fibromyalgia can be diagnosed through careful evaluation of symptoms, use of diagnostic criteria (for example, the American College of Rheumatology’s diagnostic criteria, which uses a widespread pain index and symptom severity score) and ruling out other physical causes by use of appropriate imaging and blood tests. Recent guidance from the Royal College of Physicians notes that patients with fibromyalgia may not initially report having widespread pain, rather presenting with a focal pain such as back pain and recommends that recurrent presentations with pain should prompt consideration of fibromyalgia.
Examination
General principles
GP registrars will be familiar with the ‘look, feel, and move’ approach to joint examination. Joints should be assessed for redness, heat, deformity, tenderness, swelling, and range of movement. In a general practice setting, if the patient presents with a definite mono-arthralgia, for example knee pain on walking, a focussed examination of the affected joint plus the joints above and below should be conducted. In patients presenting with poly-arthralgia, a general screening tool can be used, for example, the GALS (Gait, Arms, Legs, Spine) screen, which is well-summarised on the Versus Arthritis website. It is worth considering examination of other systems, such as respiratory or abdominal, if extra-articular symptoms are present or a systemic condition is suspected. As low back pain and knee pain are the most common MSK presentations, these will be covered in more detail.
Low back pain assessment
Low back pain is one of the most common MSK presentations in general practice (Margham, 2011). Examination of the thoraco-lumbar spine should begin with general inspection, plus observation of gait and posture. Any spinal abnormalities should be noted, including kyphosis, scoliosis and abnormal lumbar lordosis. Movements should include forward flexion, lateral flexion, lateral rotation, and extension. Flexion may be measured using the modified Schober’s test (see Box 2). Palpation of the mid and lateral aspects of the spine and the paraspinal region should be performed. Significant tenderness on percussion is a red flag, as it may indicate infection, fracture or neoplasm. Modified Schober’s test. With the patient standing, draw a horizontal line between the posterior superior iliac spines Draw two further lines, one 5 cm below and one 10 cm above the first line Ask the patient to bend forwards to touch their toes and re-measure the distance between the top and bottom line.
Special tests of the thoraco-lumbar spine should include: straight leg raise (flexing at the hip with extended knee and dorsiflexed ankle, which can cause pain or paraesthesia in a nerve root distribution if there is nerve root irritation), and femoral stretch test (flexing the knee with the patient prone and anterior thigh on the couch, which may cause anterior thigh pain with irritation of the femoral nerve roots) (Knott, 2018).
In patients with back pain, bear in mind the many non-MSK causes, including urological, gynaecological, gastrointestinal, and aortic aneurysm. Cauda equina syndrome (CES) is an important cause of low back and leg pain which must not be missed as time is of the essence when treating this problem. Symptoms of CES include: low back pain; leg pain; lower limb motor or sensory abnormalities; bowel or bladder dysfunction; loss of anal sensation and/or tone; and perineal paraesthesia. Rectal examination should also, therefore, be considered as part of a low back pain assessment (Knott, 2019).
Knee pain assessment
Knee examination and special tests can help to distinguish between different common causes of knee pain. Inspection should look for visible abnormalities such as varus and valgus deformities, muscle-wasting and fasciculation, and asymmetry. Gait should be observed. Movements should include active and passive flexion and extension. Palpation of the knee should be performed, noting heat, swelling, and tenderness. There are several tests for knee effusion, including the bulge test and patella tap. Bulge test: sweep the edge of the hand upwards from the medial side of the patella and then downwards to the lateral side, observing for a bulge as the fluid is moved. Patella tap: apply pressure from the proximal side of the knee to empty fluid from the suprapatellar pouch, then tap down on the patella to feel if the patella bounces on the underlying femur (Wang et al., 2020).
Special tests at the knee include the anterior drawer test, which tests the integrity of the cruciate ligaments. This involves having the patient in a supine position with knee flexed to 45° then the foot is placed firmly on the couch and the hands are placed just below the knee with the thumbs along the joint line on either side. The tibia is then pulled forward. Excessive give forwards suggests anterior cruciate ligament damage, whereas backwards movement suggests posterior cruciate damage (Ellanti and Mulhall, 2015). Collateral ligaments can be tested using the medial and lateral stress test. Medial stress test: one hand is placed above the knee laterally with the other at the ankle medially, and the knee flexed between 0 and 30°. Pressure is applied medially with the upper hand and laterally with the lower hand. The joint line can be palpated to feel for gapping at the joint line. The lateral stress test is performed similarly with the knee stabilised and lateral pressure applied.
Meniscal tears can present with pain in the joint line, swelling, clicking, catching, locking and giving way (Bhan, 2015). There are several tests that can be used to aid diagnosis, but these are not hugely reliable and should be used in conjunction with the history to decide whether further investigation is required. One meta-analysis showed McMurry’s test had a sensitivity of 61% and specificity of 84%, whereas joint line tenderness had a sensitivity of 83% and specificity of 83% (Smith et al., 2015). McMurry’s test is performed by holding the knee with one hand while the other hand holds the sole of the foot, fully flexing the knee, and then extending to 90° while rotating the leg internally. A positive test is if a thud or click is felt.
Further investigation
Diagnosis may be apparent following the history and examination, but it may be appropriate to arrange further investigation if the diagnosis is unclear, or if there is suspicion of an underlying systemic or malignant condition, or a need to assess severity of disease (for example, if referring on to secondary care). Red flags such as weight loss, fever, night sweats or night pains should prompt onward urgent referral, and any suspected septic arthritis should be sent for urgent further assessment.
In the case of suspected inflammatory arthritis it may be appropriate to request blood tests from primary care, for example, to confirm the presence of raised inflammatory levels or to look for autoantibodies, although patients should be referred to secondary care even if inflammatory markers and autoantibodies are normal. Tests could include inflammatory markers (c-reactive protein and/or erythrocyte sedimentation rate) and full blood count, plus autoimmune markers, such as rheumatoid factor, anti-cyclic citrullinated peptide antibody (both associated with RA), and anti-nuclear antibodies including double-stranded DNA (associated most often with SLE. HLA-B27 may be requested by secondary care in suspected ankylosing spondylitis but this is not usually recommended in primary care.
Plain X-rays can be useful in inflammatory arthritis, as they may show signs of joint erosion, a negative prognostic indicator as it suggests joint damage has already occurred. Erosions may also be seen in erosive OA, crystal arthropathies, and septic arthritis, as well as some other conditions such as sarcoidosis and tumours (Schett and Gravallese, 2012). Ultrasound is increasingly used in secondary care to assess for inflammation within the joint, but is not usually requested from primary care (Kaeley et al., 2020)
For OA, the latest guidance from the NICE (NICE, 2022b) does not recommend imaging, but rather advises that adults over 45 years in age can be diagnosed clinically if they have joint pain on activity, with any morning joint stiffness not lasting longer than 30 minutes. The decision to refer on to secondary care will depend on the severity of the patient’s symptoms and the clinician’s clinical judgement, though it is usual to explore other initial management options first, as per the 2022 guidance from NICE.
Key points
Joint pain is one of the most common presentations to general practice and there are many possible causes, therefore, a thorough history and examination are important
Red flags for serious underlying causes including cancer and infection should always be screened for
Consider the psychological and functional impact on patients
Any patient presenting with signs or symptoms of septic arthritis should be admitted for urgent investigation and treatment
Patients in whom inflammatory arthritis is suspected require urgent referral and investigation
OA can be diagnosed clinically
