Reasoning GP · Algorithm · 1-page summary
Musculoskeletal problems in children
For: children and young people with limb or joint pain, a limp, back pain or "growing pains", in primary care. Not for: adults (use the joint pain algorithm). Limp detail: limping child algorithm; cancer detail: paediatric cancer referral algorithm.
Core rule: fever with a hot joint, non-use of a limb or refusal to weight-bear is septic arthritis or osteomyelitis until proven otherwise. Examine the hip in every child with knee or thigh pain. Normal bloods, a normal X-ray or a child who briefly walks exclude nothing.
0Stop — call 999 now — before any history
- Physiological instability, altered consciousness, shock, severe respiratory compromise or rapid deterioration (NG254) → 999
- Acute neurology: new leg weakness or bladder/bowel symptoms; severe trauma (fall from height, road traffic collision) → 999
- Otherwise suspected septic arthritis or osteomyelitis is Same-day hospital. Investigations must not delay same-day specialist discussion; aspiration is for the hospital team.
1Triage by age — ages are not absolute
| Age | Think of |
|---|---|
| <3 y | Toddler fracture, septic arthritis, osteomyelitis, DDH, NAI, leukaemia. Unexplained, febrile or non-weight-bearing limp → Same-day. Never growing pains. |
| 3–10 y | Transient synovitis, growing pains, post-viral; Perthes (4–10 y), septic arthritis, JIA, malignancy |
| 10–16 y | Osgood-Schlatter, Sever's, anterior knee pain; SUFE (knee pain too), bone tumour, JIA |
2Screen — one row is enough
- Infection: fever with hot swollen joint, limb swelling, non-use, can't weight-bear, pain on passive movement; or red, hot, swollen single joint → Same-day hospital
- SUFE: adolescent with hip, groin, thigh or knee pain, limp or reduced internal rotation → non-weight-bearing; Same-day ortho + imaging
- Fracture: significant trauma, deformity, can't weight-bear → Same-day
- NAI: bruised non-mobile child, inconsistent or delayed story, patterned injury → Same-day safeguarding per local procedures
- Leukaemia: unexplained petechiae or hepatosplenomegaly → Immediate specialist. Pallor, fatigue, fever, infections, nodes, bruising, persistent bone pain → FBC ≤48 h + urgent paediatrics
- Bone tumour: unexplained bone pain or swelling → consider X-ray ≤48 h (NG12). Persistent, focal or progressive night pain → urgent paediatric discussion.
3Assess — only once blocks 0–2 are answered
☐ Temperature, pallor, bruising, rash, nodes, liver, spleen ☐ Gait; pGALS ☐ Hip in every knee or thigh pain ☐ Compare legs; pulses and neurology after trauma; spine, abdomen, testes as indicated
FBC, CRP, ESR if febrile or unwell: cannot rule septic arthritis in or out. Perthes/SUFE: AP pelvis + frog-leg lateral of both hips (cross-table if unstable SUFE). MRI via specialists.
4Classify — only if the screen is negative
- Growing pains — usually 3–12 y, bilateral leg (not joint) pain, evenings, gone by morning, normal exam → reassure, no tests.
- Transient synovitis — about 3–10 y, acute limp, post-viral, well, usually weight-bearing. Diagnosis of exclusion.
- Perthes — restricted abduction or internal rotation, Trendelenburg gait → X-ray + Urgent ortho, even if the X-ray is normal.
- JIA — persistent joint swelling, inflammatory morning stiffness or loss of function → paediatric rheumatology; do not wait 6 weeks.
- Mechanical — Osgood-Schlatter, Sever's, overuse; hypermobility (Beighton ≥6/9 in children) → manage in primary care.
- Uncertain — persistent limp or abnormal examination → reassess; imaging and paediatric review by findings.
5Treat today — only these
- Pain: paracetamol PRN; ibuprofen with food for inflammatory pain (avoid if dehydrated, renal impairment, NSAID-sensitive asthma, GI bleeding). Doses per BNFC and local formulary.
- No codeine under 12 (MHRA); codeine or tramadol not routine for benign limb pain. Both simple analgesics → written schedule.
- Transient synovitis: analgesia, relative activity restriction, resume weight-bearing as pain improves. Suspected SUFE: non-weight-bearing.
- Osgood-Schlatter / Sever's: cut running and jumping, keep swimming or cycling, stretch, ice. Growing pains: massage, heat.
6Refer routinely
- Urgent ortho Perthes, persistent limp with abnormal X-ray, suspected DDH.
- Paediatric rheumatology: suspected JIA (sooner if multiple joints, systemic or eye symptoms). Diagnosed JIA needs uveitis eye screening, whatever the eye symptoms.
- Paediatrics: hypermobility with significant impairment; atypical or severe growing pains. Physio: hypermobility, recurrent sports injury. Osgood-Schlatter not settling → MSK/ortho.
7Never reassure by
- Normal CRP, ESR, WCC or FBC — early infection, leukaemia and bone tumours.
- A normal X-ray — early Perthes, osteomyelitis, bone tumour; SUFE needs a lateral view.
- A low-grade fever, or the child being briefly able to walk.
- A normal knee in knee or thigh pain — examine the hip.
- "Growing pains" under 3, or with unilateral, focal or daytime pain or a limp.
- An ultrasound effusion or Kocher-type score — neither separates septic arthritis from transient synovitis.
8Safety-net — say it, then document it
999 “Call 999 if your child collapses, is very drowsy, struggles to breathe or gets rapidly worse, has sudden severe pain and can't stand, a serious injury, or new leg weakness or bladder or bowel problems.” Same day “Get seen today for a fever with a limp or joint pain, refusing to stand, a hot swollen joint, being unwell or not eating, night pain that persists, is in one spot or is worsening, or pain painkillers don't help.”
Review: transient synovitis within 24–48 h and at 1 week; not resolved by 1 week → X-ray hip + paediatric ortho/rheumatology referral. A benign diagnosis that gains red flags → Urgent paediatric re-referral
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies, incl. no safeguarding concern
Well, afebrile, weight-bearing; gait seen
pGALS and hip examined; one benign cause, or uncertainty stated
Review booked with owner and date
Safety-net given and documented
Summary of the full Reasoning GP paediatric MSK algorithm, which holds the detail, examination, investigations and evidence. Sources: NICE NG12 (updated April 2026), NG254, NG143; MHRA codeine advice; pGALS; BSPAR/RCOphth JIA uveitis screening. Clinical reference — follow local paediatric and safeguarding policies and check doses in the current BNFC.