Joint examination and approach to the painful joint

• A painful joint is first sorted into two groups: inflammatory pain (worse at rest, with morning stiffness) and mechanical pain (worse on use, brief stiffness).
• The number of joints involved next narrows the differential: one hot joint is septic arthritis until proven otherwise, then crystal or blood.
• Polyarthritis is patterned by symmetry, joint size, axial involvement and morning stiffness duration.
• The single most useful investigation in a swollen joint is aspiration: fluid sent for cell count, crystals, Gram stain and culture.
• History and examination come before imaging; plain X-rays are often normal early and do not exclude septic arthritis.
• Red flags (fever, inability to bear weight, immunosuppression, prosthetic joint) override algorithms and demand urgent referral.

By the end of this page you should be able to:

1. Take a focused history that separates inflammatory from mechanical pain and records the features that matter.
2. Examine any joint systematically and adapt the examination to the hip, knee, shoulder, wrist and small joints.
3. Recognise septic, crystal and haemorrhagic monoarthritis and know why crystals and infection can coexist. ^[3]
4. Read a synovial fluid result and understand what each column means, including its limits.
5. Apply a simple pattern-based differential for polyarthritis and know the red flags.
6. Plan first-line investigations and an initial management plan, and know when to refer urgently.
7. Name the guideline documents that underpin the approach and the year of each.

This page teaches a clinical method rather than a single disease: the patient with joint pain or swelling, from first contact to a working diagnosis. It follows the same structure for every patient, so that nothing important is missed, and then adapts the depth of investigation to the presentation. It is written for students who will be expected to examine real joints early in training and to defend their reasoning in examinations. ^{[7] [1]}

The core risk in joint assessment is missing septic arthritis, which carries a case-fatality rate of about 11 percent and can destroy cartilage within one to two days of onset. ^{[1] [2]} The opposite error is over-treating every swollen joint as septic and exposing patients to unnecessary antibiotics and hospital admissions. The approach below tries to keep both errors in view at every step. ^[7]

Joint pain is not one diagnosis. The differential for acute arthritis in standard sources spans crystal-induced disease, infection, inflammatory arthritis, osteoarthritis, systemic infection, tumour and other causes such as haemarthrosis. ^[2] For learning, it helps to group causes in three ways.

By joint count. A single joint (monoarthritis) is usually septic, crystal (gout or pseudogout), traumatic or haemorrhagic, although a systemic inflammatory disease can declare itself in one joint first. Two to four joints (oligoarthritis) point toward the spondyloarthropathies, reactive arthritis, psoriatic arthritis and late or oligoarticular infection. Five or more joints (polyarthritis) raise the systemic inflammatory arthritides: rheumatoid arthritis, systemic lupus erythematosus, viral arthritis, and Adult-onset Still disease.

By inflammatory versus mechanical quality. Inflammatory pain is worse at rest and at night, with morning stiffness lasting more than a short period, and the joint is swollen, warm or "boggy". Mechanical pain is provoked by load and relieved by rest, with brief stiffness; there may be crepitus and bony swelling rather than true synovitis. ^{[6] [8]}

By urgency. The conditions that must not be missed are septic arthritis, fracture or tendon rupture after trauma, acute limb ischaemia, cauda equina if the back and leg are involved, and suspected (especially metastatic) malignancy. Everything else is worked up in primary or outpatient care.

Constitutional symptoms such as fever, rigors and chills occur in septic arthritis but are neither specific nor very sensitive. Fever is present in about 40 to 60 percent of people with the condition, and in smaller reviewed series about 57 percent. Elderly and immunosuppressed patients may have a muted or atypical picture. ^[1]

A good history is the diagnosis in many cases. Ask in the patient's own words first, then fill in the details.

Onset and time course. When did it start? Sudden onset over hours suggests crystal arthritis (gout often overnight) or haemarthrosis; infection builds over hours to days; osteoarthritis and chronic inflammatory disease have an insidious course over weeks to months. Ask whether the pain is constant or episodic, and whether episodes resolve completely between attacks.

Number and distribution. One, two to four, or many joints? Symmetry matters: rheumatoid arthritis classically involves small joints of the hands and feet symmetrically; psoriatic and reactive disease is often asymmetric and may involve large joints or the spine.

Inflammatory quality. Pain at rest, pain at night, and morning stiffness longer than a short period point to synovitis. Stiffness that eases within 30 minutes of getting up, and pain brought on by use, point to osteoarthritis. ^{[6] [8]}

Aggravating and relieving factors. Load, rest, time of day, weather, and response to simple analgesia. Mechanical pain worsens with weight bearing and repetitive use and improves with rest. Inflammatory pain often eases with gentle movement and worsens with prolonged immobility.

Trauma and bleeding. Even minor trauma can precipitate haemarthrosis in someone on anticoagulants or with a bleeding disorder. Ask about anticoagulant and antiplatelet use and about haemophilia or von Willebrand disease.

Infection risk and exposures. Recent skin infection, operation, injection or prosthesis; sexual activity (gonococcal arthritis), tick exposure (Lyme disease), immunosuppressive medication, diabetes, rheumatoid arthritis, intravenous drug use, age over 80. Ask about a preceding genitourinary or gastrointestinal illness (reactive arthritis). ^[2]

Extra-articular features. Skin and nail changes (psoriasis), eye inflammation (uveitis), mouth or genital ulcers, rashes, bowel or genitourinary symptoms, Raynaud phenomenon, dry eyes or mouth, fever and weight loss. These are often what separates one inflammatory disease from another.

Family and past history. Gout, rheumatoid and psoriatic arthritis, spondyloarthritis, and bleeding disorders cluster in families. Personal history of crystal arthritis matters: urate crystals in fluid or gout on previous occasions.

Function. What can the patient no longer do? This guides urgency, referral and later outcome measurement.

Work from the general to the specific: general impression, gait, posture, then the joint and the regions above and below it. Look at both sides and compare. Examine all joints, even those not complained of, because polyarthritis is often under-reported.

General. Well or ill; pyrexia; weight; rashes, psoriasis, tophi, nail changes; effusions elsewhere. Check the lymph nodes and spleen if systemic disease is suspected.

Regional limb. Colour, temperature, swelling, wasting, deformity, scar. Test active and passive range, stability, special tests for the specific joint.

Joint itself. Synovitis is a spongy or boggy swelling, often with warmth and tenderness, and reduced range in all directions because of pain and guarding. An effusion feels fluctuant. Osteoarthritis gives bony (hard) swelling, crepitus and restricted movement with pain at the extremes only. Tenosynovitis gives linear swelling along a tendon, worse on resisted movement or stretch.

Gait and posture. Antalgic gait, Trendelenburg pattern, foot posture and footwear.

A common reason students lose marks is forgetting that examination differs by joint. The following are the points worth making explicit.

Shoulder. Look from the front and behind for wasting of the supraspinatus and infraspinatus, swelling of the subacromial bursa, and step deformity suggesting old dislocation. Measure active and passive flexion, abduction, external and internal rotation. Painful arc between 60 and 120 degrees of abduction suggests subacromial impingement (some sources describe the arc as approximately 70 to 120 degrees); full passive movement preserved but painful active abduction points to a rotator cuff tendon. Test Jobe (supraspinatus), resisted external rotation (infraspinatus/teres minor) and belly-press (subscapularis). Palpate the acromioclavicular joint and the bicipital groove. Always examine the neck and the referred pain pattern. ^[9]

Elbow. Terminal extension and flexion; carrying angle; cubital tunnel and ulnar nerve; olecranon and rheumatoid nodules; gouty tophus. Test valgus and varus stability, pronation and supination, and resist wrist extension for lateral epicondylitis.

Wrist and hand. Inspect for synovitis at the metacarpophalangeal and proximal interphalangeal joints, ulnar deviation, swan-neck and boutonniere deformities, squaring at the first carpometacarpal joint and Heberden and Bouchard nodes. Squeeze the metacarpophalangeal joints gently: tenderness implies active synovitis. Test wrist flexion and extension, radial and ulnar deviation, pronation and supination, and thumb opposition, abduction and extension. Assess median nerve (carpal tunnel) and ulnar function.

Hip. Observe standing and sitting, leg length and muscle wasting. With the patient supine, test flexion (Thomas test), internal and external rotation in flexion, abduction and adduction, and extension in the prone position. The FABER (flexion, abduction, external rotation) test stresses the hip and the sacroiliac joint. Pain on passive internal rotation with the hip flexed is sensitive for hip disease. Check the knee, because hip disease can present as knee pain. Measure gait and the straight leg raising if back pain coexists.

Knee. Look for quadriceps wasting, varus or valgus, bony swelling, effusion, wounds and scars. Palpate the joint line, the pes anserinus, the prepatellar and infrapatellar bursae, and the popliteal fossa. Measure active and passive flexion and extension. Test for an effusion (patellar tap for large effusions, sweep test for small ones), ligament stability (anterior and posterior drawer, Lachman, varus and valgus stress), and meniscal pathology (joint-line tenderness, McMurray, Thessaly). Always test the hip and the spine if knee pain has an atypical pattern.

Ankle and foot. Inspect alignment, swelling, and Achilles and tibialis posterior tendons. Test dorsiflexion, plantarflexion, inversion and eversion; check subtalar movement. Look for midfoot swelling, first metatarsophalangeal tenderness (gout) and forefoot deformities. Squeeze the metatarsals gently; tenderness implies active synovitis. Observe walking and turning.

Spine. If axial pain or stiffness is a feature, test flexion (Schober), chest expansion and sacroiliac stressing. Ask about back pain at night and alternating buttock pain.

Aspiration is the pivot of the assessment of any swollen joint. It should be done if there is an effusion, before antibiotics if sepsis is possible, and in any joint that is red, hot or severely painful. It is not the last resort; it is the diagnostic step.

Indications: suspected septic arthritis; differentiating gout or pseudogout; an unexplained effusion; relief of a tense effusion. Relative cautions: overlying skin infection, severe coagulopathy, and a prosthetic joint, which is usually referred to orthopaedics. The 2006 BSR hot swollen joint guideline confirms that warfarin does not contraindicate needle aspiration. ^{[7] [1]}

Send every sample for: appearance and viscosity by the bedside (colour, clarity, viscosity); total and differential cell count; Gram stain; aerobic and anaerobic culture; crystal microscopy under polarised light; and, if the presentation is atypical or HIV or Lyme disease is possible, special tests. Blood cultures should be added when infection is suspected. ^{[2] [3]}

Table 1 gives the standard interpretation. These ranges are guides rather than cut-points; they vary between laboratories and must be read with the clinical picture. ^[2]

Two warnings matter in examination answers. First, a white cell count under 50,000 per microlitre does not exclude septic arthritis, and very low counts are typical in atypical infection and periprosthetic joint infection. ^[2] Second, the presence of crystals does not exclude infection: concomitant gout or pseudogout with septic arthritis is well described, and elevated synovial fluid white cell counts and CRP occur in both crystal and septic arthritis. ^{[2] [3]}

Serum markers support but do not confirm the diagnosis. In one study, serum ESR at 10 mm per hour or above was 98 percent sensitive and CRP at 2.0 mg per dL (20 mg per L) or above 92 percent sensitive for septic arthritis when low cut-offs are used, which helps rule septic arthritis out but is not diagnostic. Procalcitonin at 0.5 ng per mL or above has higher specificity. ^{[1] [2]}

Investigations follow the clinical picture; they do not replace it. Plain radiographs establish a baseline and can show chondrocalcinosis (suggesting pseudogout), fracture or advanced osteoarthritis, but they are often normal in early septic arthritis or gout. Ultrasonography guides aspiration in the hip, shoulder and small joints, and can demonstrate the double contour sign of gout and a joint effusion. Magnetic resonance imaging is the best test for osteomyelitis and soft tissue infection and helps differentiate septic from non-septic disease; if septic arthritis is suspected clinically, do not wait for imaging before aspirating. ^{[2] [1]}

Blood tests: full blood count, ESR and CRP (raised in inflammation and infection, non-specific), urate (best measured between flares; a normal result does not exclude gout during an acute attack), renal function, liver function, rheumatoid factor and anti-CCP antibodies when inflammatory polyarthritis is suspected, and HLA-B27 when spondyloarthritis is likely. Urate measured during a flare is often normal or low; if it is 360 micromol per litre (6 mg per dL) or above between flares, it supports gout. ^[5]

Crystal analysis needs fresh fluid examined promptly by polarised light microscopy. If gonococcal or other atypical infection is possible, send PCR on fluid and on mucosal swabs. Synovial biopsy may be needed when fluid is negative and suspicion remains. ^[2]

Septic arthritis. Usually a single large joint (knee, then hip, shoulder, ankle, elbow, wrist) is involved; infection is oligoarticular in up to a fifth of cases. ^[2] Organisms reach the joint haematogenously most often. Staphylococcus aureus and streptococci dominate in adults; in older people gram-negative organisms cause roughly 23 to 30 percent of cases; gonococcal infection is more likely in sexually active young adults. ^{[1] [2]} The joint is severely painful with movement, often with an obvious effusion. Infection must be excluded even if the fluid is not purulent: neither absence of organisms on Gram stain nor a negative culture excludes septic arthritis. ^{[1] [7]}

Suspected cases are aspirated before antibiotics, blood cultures taken, and empiric intravenous antibiotic therapy with cover against S. aureus and streptococci started once fluid has been obtained; the BSR-based pathway and AFP tables guide choices. Duration is at least two weeks for small joints and commonly at least six weeks for others, adjusted to organism and response. ^{[2] [1]} Definitive treatment is often surgical washout or arthroscopy, particularly for the hip and shoulder, and prosthetic joints are managed with orthopaedic input.

Crystal arthropathies.

• Gout causes abrupt (often overnight) severe pain, redness and swelling, classically first metatarsophalangeal but also midfoot, ankle, knee, hand, wrist or elbow. NICE NG219 recommends assessing the possibility of septic arthritis, calcium pyrophosphate crystal deposition and inflammatory arthritis in any painful, red, swollen joint, and referring immediately if sepsis is suspected. ^[5] Definite diagnosis is by polarised light microscopy showing negatively birefringent needle-shaped monosodium urate crystals. A serum urate of 360 micromol per litre (6 mg per dL) or more supports gout, measured ideally between flares; if it is low during a flare, repeat at least two weeks after resolution. Joint aspiration and microscopy is used when the diagnosis remains uncertain. ^[5]

• The 2015 ACR and EULAR gout classification criteria (entry criterion: at least one episode of swelling, pain or tenderness in a peripheral joint or bursa; sufficient criterion: MSU crystals in fluid or tophus) have 92 percent sensitivity and 89 percent specificity. If crystals are not demonstrated, a score of 8 or more across clinical, laboratory and imaging domains classifies gout. ^[4]

• Pseudogout (calcium pyrophosphate deposition) favours larger joints (knee, wrist, hip) and older patients; positively birefringent rhomboid crystals are seen; radiographs may show chondrocalcinosis. It cannot reliably be distinguished from septic arthritis or gout clinically, so aspiration is essential when infection is a possibility.

Haemarthrosis. Blood in the joint after trauma, or spontaneously with anticoagulation, haemophilia or other bleeding disorders. The fluid is frankly bloody. The cause must be found; repeated unexplained haemarthrosis needs investigation for malignancy or a bleeding diathesis. Association with anticoagulant use should not stop aspiration: the BSR pathway confirms that warfarin does not contraindicate needle aspiration. ^{[7] [2]}

Polyarthritis is best approached systematically, and one open-access review of the topic sets out the classification by duration (acute or chronic), joint size (large or small) with or without axial involvement, symmetry, and clinical pattern (migratory, additive, intermittent). ^[3] Applying those axes to the common diseases:

• Rheumatoid arthritis. Chronic, symmetric, small joints of the hands and feet (metacarpophalangeal, proximal interphalangeal, metatarsophalangeal) with prolonged morning stiffness; synovitis with boggy swelling; may include neck, shoulders and knees. Red flags for sepsis apply because rheumatoid patients on immunosuppressants are at heightened risk of septic arthritis. ^[2]

• Seronegative spondyloarthropathies (ankylosing spondylitis, psoriatic, reactive, inflammatory bowel disease). Asymmetric, often large or axial joints, with enthesitis and dactylitis; psoriasis, nail changes, uveitis and bowel disease; stiffness worse after rest but often affecting the back and pelvis. Morning stiffness may be prominent.

• Systemic lupus erythematosus and other connective tissue disease. Polyarthritis that is often non-erosive, with rashes, photosensitivity, serositis, renal or nervous system features.

• Viral arthritis. Acute, often symmetric small joint polyarthritis following (or during) viral infection; generally self-limiting. Parvovirus B19, rubella and the alphaviruses are classic; sexually transmitted infection may produce arthritis-dermatitis syndrome.

• Rheumatic fever. Migratory polyarthritis moving from joint to joint over days, with carditis, chorea, erythema marginatum and subcutaneous nodules.

• Adult-onset Still disease. Intermittent polyarthritis with high quotidian fever, sore throat and a fleeting rash.

Inflammatory polyarthritis with persistent synovitis requires urgent referral to rheumatology. CKS recommends referral within 3 weeks for persistent synovitis, and urgent referral within 3 working days if small joints of the hands or feet are involved, more than one joint is affected, or there has been a delay of 3 months or more since symptom onset, even with normal acute-phase tests; the NICE quality standard QS33 sets urgent referral within 3 working days and specialist assessment within 3 weeks of referral. ^[8]

Management is three-layered: symptom relief, protection of function, and treatment of cause.

Pain relief. Paracetamol and topical NSAIDs first, then oral NSAIDs at the lowest effective dose for the shortest time with gastric protection where appropriate. Opioids, particularly strong opioids, are not appropriate for osteoarthritis. NICE NG226 advises against routine paracetamol for osteoarthritis unless used infrequently and other analgesics are unsuitable. ^{[6] [5]}

Non-pharmacological measures. Targeted exercise, weight management where relevant, protective footwear, pacing, and education. Exercise may increase pain at first but is beneficial in the medium term for function and symptom control. ^[6]

Cause-directed treatment. Gout flares are treated with an NSAID, colchicine or a short course of oral corticosteroid, chosen according to comorbidities, with ice packs as an adjunct; long-term urate lowering uses allopurinol or febuxostat to a serum urate below 360 micromol per litre (6 mg per dL), or below 300 micromol per litre (5 mg per dL) for tophaceous or refractory gout. ^[5] Rheumatoid and other inflammatory arthritis are managed by rheumatology with disease-modifying therapy. Septic arthritis is treated with antibiotics and drainage. Trauma is managed by the appropriate pathway.

What not to do. Do not inject a joint with corticosteroid until infection is excluded. Do not give glucocorticoids by mouth before a specialist assessment if rheumatoid arthritis is possible, because they can mask the features. Do not immobilise a hot joint without a plan for drainage.

Urgent (same day) referral: suspected septic arthritis; fracture, dislocation, tendon rupture; neurovascular compromise; a prosthesis that may be infected; or malignancy features. Urgent (usually within two weeks): suspected inflammatory polyarthritis, especially with small joint involvement; persistent synovitis of unknown cause; suspected tumour. Routine: osteoarthritis that does not respond to conservative care; diagnostic uncertainty; atypical features such as a young patient with a hot swollen joint. ^{[6] [8] [2] [7]}

Where advanced imaging, polarised microscopy or rheumatology is unavailable, a credible approach still exists. Clinical history and examination carry most of the diagnostic weight. A plain X-ray is widely available and can show chondrocalcinosis, fracture and established osteoarthritis. A joint that is acutely hot should be aspirated whenever expertise allows, and cloudy fluid is a sign of infection rather than a number. If sepsis is possible, start antibiotics with staphylococcal and streptococcal cover after aspiration. A basic cell count and Gram stain is more informative than no test at all. Send every resected tissue or biopsy for histology if access permits.

• Joint pain is first classified as inflammatory or mechanical, and then by number of joints, system and urgency.
• Inflammatory pain: worse at rest and night, morning stiffness lasting more than 30 minutes (NICE QS33) or more than 15 to 30 minutes (CKS), warm or boggy swelling. Mechanical pain: worse on use, brief stiffness, bony swelling. ^[8]
• One acutely hot, swollen, painful joint with restricted movement is septic arthritis until proven otherwise. ^[7]
• Septic arthritis has a case-fatality rate of about 11 percent; in-hospital mortality overall is reported as 7 to 15 percent. ^[3]
• Neither a Gram stain nor culture that is negative excludes septic arthritis; nor does a white cell count under 50,000 per microlitre.
• Crystals and infection can coexist; never let a positive crystal result close the case of a truly hot joint.
• Aspiration is the central investigation of a swollen joint; send cell count, differential, crystals, Gram stain and culture.
• Plain X-rays are often normal early; MRI or ultrasound add detail when needed but should not delay aspiration.
• Gout presents abruptly, classically overnight, with first metatarsophalangeal or midfoot, ankle or knee involvement; pseudogout favours older patients and larger joints.
• Polyarthritis is patterned by duration, symmetry, joint size, axial involvement and morning stiffness.
• Red flags override the algorithm and require urgent referral and treatment.
• NICE, BSR and ACR documents differ in emphasis; the clinician should name which edition was used and check local guidance.

Rheumatoid arthritis; osteoarthritis; gout and calcium pyrophosphate deposition; septic arthritis; spondyloarthropathies (ankylosing spondylitis, psoriatic arthritis, reactive arthritis); systemic lupus erythematosus; shoulder, knee and hip regional pain; deep vein thrombosis and other causes of a swollen calf; haemophilia and bleeding disorders.