Septic arthritis is a surgical emergency — delayed treatment (>24 hours) leads to irreversible joint destruction, growth plate damage, and chronic disability. Kocher/Caird-type criteria (fever, refusal to weight-bear, raised WCC, ESR, CRP) are supportive risk tools for septic arthritis of the hip, not diagnostic tests — they have limitations in different populations, early disease and infections such as Kingella kingae. A child with clinical concern requires same-day paediatric/orthopaedic assessment regardless of initial blood results.
Slipped upper femoral epiphysis (SUFE) requires urgent surgical pinning to prevent avascular necrosis of femoral head. Presents as hip, groin, thigh or knee pain; obesity is an important risk factor but lean adolescents can also develop SUFE. Keep non-weight-bearing while awaiting same-day orthopaedic assessment. Delay = slip progression = lifelong hip arthritis.
Childhood malignancy (leukaemia, neuroblastoma, osteosarcoma) can present with vague MSK symptoms. Night pain can occur with benign conditions, but persistent or unexplained night pain — especially when focal, progressive or with swelling, limp, weight loss, pallor, bruising or fatigue — should prompt urgent assessment. Use the full clinical picture rather than an automatic test rule. Missing malignancy has catastrophic consequences.
Age is the strongest diagnostic clue — different conditions cluster at different developmental stages. Toddler fractures (<3 years), Perthes (commonly 4-10 years), SUFE (early adolescence, often around 10-16 years) — age ranges are not absolute. Age-inappropriate diagnosis should trigger reassessment.
Functional impact distinguishes serious from benign pathology. Child still playing, running, climbing stairs = likely benign. Refusing to weight-bear, carried by parents, missing school = urgent assessment needed.
Night pain needs context in children. Growing pains are typically bilateral, in the legs (not the joints), occur in the late afternoon or evening and may wake the child, but resolve by morning with normal activity, a normal examination and no limp; pain that is unilateral, localised to a joint, present in the morning or during the day, or with systemic features needs assessment. They are uncommon below the age of 5, and should not be diagnosed in a child under 3 with a limp (low threshold for same-day assessment). Persistent or progressive night pain = consider malignancy, infection, inflammatory arthritis.
Growing pains are a clinical diagnosis made after considering alternative pathology. Typical growing pains can be managed without investigation when the history and examination are reassuring. Reassess or investigate if pain is unilateral, focal, occurs in the daytime, causes limp, persists or worsens, or is associated with abnormal examination or systemic symptoms.
Transient synovitis vs septic arthritis is the critical distinction. Kocher criteria are a supportive risk tool, not a diagnostic test. When in doubt = same-day hospital assessment; aspiration and microbiological assessment are determined by the hospital orthopaedic/paediatric team. Missing septic arthritis = permanent joint damage.
Age-specific pathology reflects skeletal maturity. Perthes (avascular necrosis femoral head) commonly occurs age 4-10 (may occur outside this range) when blood supply to epiphysis is vulnerable. SUFE occurs in adolescents when growth plate is weakest pre-fusion. Wrong age for diagnosis = reconsider.
pGALS screen is a quick, validated screen that finds abnormal joints before a focused examination. A normal screen does not exclude infection, malignancy or non-accidental injury — act on the red flags in Step 1.
Hip pathology commonly presents as knee pain in children (referred pain via obturator nerve). Always examine hip in child with knee pain, especially if knee examination normal. Missing SUFE because you only examined the knee is a medicolegal disaster.
Refusal to weight-bear is never normal. Even with transient synovitis, children can weight-bear with pain. Complete refusal = septic arthritis, fracture, malignancy, or severe Perthes until proven otherwise.
X-rays in children = radiation — effective dose matters. Only X-ray if result will change management. Normal X-ray does NOT exclude serious pathology (early Perthes, bone tumours, osteomyelitis may have normal X-rays initially).
Inflammatory markers help distinguish septic arthritis from transient synovitis but are not 100% sensitive/specific. Normal results do not exclude early septic arthritis, osteomyelitis or Kingella kingae infection. Clinical suspicion overrides bloods — if in doubt, refer for same-day specialist assessment.
MRI is gold standard for early Perthes, osteomyelitis, bone tumours, stress fractures, soft tissue masses. Avoid radiation. Arranged by specialists, not primary care. Do not delay referral waiting for MRI availability.
SUFE is a same-day surgical emergency — requires immediate surgical pinning to prevent further slip and avascular necrosis. Delay = slip progression = chronic hip arthritis requiring hip replacement in early adulthood. Any adolescent with hip, groin, thigh or referred knee pain, limp or reduced hip internal rotation should be considered to have SUFE until excluded — keep non-weight-bearing and arrange same-day orthopaedic assessment and imaging.
Perthes disease requires orthopaedic input to prevent femoral head collapse; normal radiographs do not exclude early disease and MRI or specialist follow-up may be required. It is usually unilateral but may be bilateral — bilateral disease needs specialist assessment, with emergency transfer depending on clinical status. Treatment (containment, bracing, or surgery) is time-sensitive — delayed referral worsens long-term outcome (hip arthritis, leg length discrepancy).
Juvenile idiopathic arthritis is a diagnosis of exclusion. JIA is classified as joint swelling (not just pain) persisting >6 weeks, but referral should not wait six weeks: persistent swelling, inflammatory morning stiffness or loss of function should prompt paediatric/rheumatology referral, especially with multiple joints, systemic or eye symptoms. Early rheumatology input prevents joint damage and disability.
Next steps: see Osgood-Schlatter disease
NSAIDs may help inflammatory MSK pain in children (transient synovitis, soft tissue injuries, overuse syndromes). Use an age/weight-appropriate dose and avoid in dehydration, renal impairment, NSAID-sensitive asthma, gastrointestinal bleeding and some infections.
Activity modification is treatment, not just advice. Osgood-Schlatter and Sever's disease are traction apophysitis — continuing high-impact sport perpetuates symptoms. Relative rest (reduce running/jumping, continue swimming/cycling) allows healing while maintaining fitness. Self-limiting once growth plate fuses.
Do NOT use codeine in children <12 years (MHRA warning — risk of respiratory depression in ultra-rapid metabolisers). Codeine or tramadol should not be routine treatment for benign limb pain; any use requires age, weight, respiratory and contraindication checks. If simple analgesia is ineffective, reassess the diagnosis.
Parental anxiety drives consultations — most paediatric MSK consultations are benign (growing pains, transient synovitis, minor trauma). Reassurance is therapeutic. Clear explanation of red flags empowers parents to self-manage safely while seeking help when needed.
Varied activity may be a reasonable suggestion in selected sports settings but is not a universal clinical standard. Growth plates are vulnerable to repetitive stress. Diverse activity reduces single-muscle-group overload and prevents burnout.
Vitamin D deficiency is more likely with dark skin and limited outdoor play and increases rickets risk. Supplementation advice should follow current national vitamin D guidance for the child's age and risk group.
48-hour review for transient synovitis is mandatory — septic arthritis can evolve from initially mild presentation. If fever develops or pain worsens after initial improvement = same-day reassessment. Do not assume "it's just viral".
Persistent symptoms deserve reassessment even if the initial presentation was benign; urgency depends on examination, age, trauma, systemic symptoms and weight-bearing. Early Perthes, stress fractures, bone tumours can have delayed X-ray changes. Normal initial X-ray does not exclude serious pathology — clinical deterioration overrides imaging.
Night pain can occur with benign conditions but should never be dismissed — persistent, focal or progressive night pain needs urgent assessment. If benign diagnosis (growing pains) develops night pain = urgent re-referral for malignancy/infection exclusion. Changing pattern = changing diagnosis.