Joint pains/ swellings – kids
DDx
- “ARTHRITIS”
- A – Avascular necrosis & epiphyseal disorders
- R – reactive & post infectious arthritis
- T – Trauma – accidental/ non accidental
- H – haematologic eg. Leukaemia, bleeding diasthesis
- R – Rickets, metabolic & endocrine disorders
- I – Infection eg. Septic arthritis, OM, Parvovirus associated arthrtisi
- T – tumour eg. Osteosarcoma, lymphoma, neuroblastoma
- R – systemic rhematologic diseases
- Note Juvenile idiopathic arthritis is a diagnosis of exclusion of above
| Mnemonic | Typical age window* | Hall-mark clinical features / red flags | Examples & comments | Initial work-up pointers |
|---|---|---|---|---|
| A Avascular necrosis & epiphyseal disorders | 4 – 10 y (Perthes), 10 – 16 y (SUFE) | Limp, ↓ range of motion (internal rotation), insidious groin / knee pain. Red flag = sudden inability to weight-bear. | • Legg-Calvé-Perthes • Slipped upper femoral epiphysis (SUFE) • Transient osteochondroses (Köhler, Sever, Osgood-Schlatter) | Pelvic / hip x-ray (frog-leg lateral), ESR/CRP usually normal. Urgent ortho if SUFE suspected. |
| R Reactive & post-infectious arthritis | 1 – 4 w after viral (any age) or GI / GU infection (school age / teens) | Asymmetric oligo-arthritis, often lower limbs; enthesitis; history of diarrhoea, urethritis or viral URTI. | • Post-streptococcal arthritis • Post-viral (parvovirus B19, enterovirus, COVID-19) • Reactive arthritis after Salmonella, Shigella, Campylobacter, Yersinia, Chlamydia | ESR/CRP mild ↑; throat swab, ASOT, stool MCS, serology for parvovirus, HLA-B27 if recurrent. |
| T Trauma (accidental / non-accidental) | Any age; toddlers & adolescents peaks | Localised swelling, bruising, reluctance to move limb; consider inconsistent history → NAI. | • Fracture (including toddler’s fracture) • Ligament / meniscal injury • Overuse (stress fracture, apophysitis) | Plain radiographs ± ultrasound; coag profile / skeletal survey if NAI suspected. |
| H Haematological | 2 – 10 y (leukaemia), any age (bleeding diathesis) | Bone pain > joint pain, night pain, pallor, bruising, hepatosplenomegaly. | • Acute lymphoblastic leukaemia • Haemophilia, von Willebrand disease | FBE & film (blasts, cytopenias), LDH, urate, coag profile. Urgent haematology referral if abnormal. |
| R Rickets / metabolic & endocrine | Infants (nutritional), adolescents (rapid growth) | Generalised bone pain/swelling, genu varum/valgum, rachitic rosary, delayed milestones. | • Nutritional vit D deficiency • Renal rickets, hypophosphatasia, hypothyroidism | Ca, PO₄, ALP, PTH, 25-OH vit D, renal panel; wrist x-ray changes. |
| I Infection (septic arthritis, osteomyelitis, viral) | Neonate, < 3 y, & adolescence highest risk | Acute mono-arthritis, pseudoparalysis, fever, refusal to bear weight. Severe pain with passive movement → septic joint until proven otherwise. | • Septic arthritis (Staph aureus, Kingella in < 4 y) • Acute haematogenous osteomyelitis • Parvovirus-B19 arthritis, viral polyarthritis | Joint aspiration & cultures, blood cultures, FBE, ESR/CRP, MRI or US if osteomyelitis suspected. Empiric IV antibiotics after aspirate. |
| T Tumour (primary or metastatic) | Bimodal: 10 – 20 y (osteosarcoma, Ewing), < 5 y (neuroblastoma mets) | Constant bone pain (often night), swelling, systemic “B” symptoms. | • Osteosarcoma, Ewing sarcoma • Metastatic neuroblastoma, lymphoma | Plain films (sunburst, onion-skin), MRI, LDH, ALP, urgent oncology referral. |
| R Systemic rheumatological diseases | 1 – 3 y (systemic JIA), 8 – 12 y (oligo/poly JIA, enthesitis-related), teens (SLE, vasculitis) | Chronic (> 6 wk) joint swelling/stiffness, morning gelling, rash, uveitis, fever spikes. | • Juvenile idiopathic arthritis (oligo, poly, systemic, ERA) • SLE, Henoch-Schönlein purpura, Kawasaki, sarcoid | ANA, ds-DNA, ENA, HLA-B27, ESR/CRP, FBE, U&E; slit-lamp exam; early paediatric rheumatology input. |
*Age bands are approximate and overlap; always consider the whole clinical picture.
Practical bedside tips
- Screen for red flags – high fever, inability to weight-bear, night sweats, bruising, severe nocturnal pain → urgent imaging / referral.
- Don’t forget the hips – hip pathology (SUFE, septic arthritis) can masquerade as knee, thigh or groin pain.
- Examine extra-articular sites – nail pitting, enthesitis, mucocutaneous lesions, lymph nodes and abdomen.
- Use ultrasound liberally in young children: painless, shows joint effusion, guides aspiration.
- Remember growing pains are bilateral, nocturnal calf/thigh aches with normal exam and daytime activity; they are a diagnosis of reassurance only after excluding the above.
Approach flow-chart (simplified)
- Is it acute (< 6 weeks) or chronic?
- Mono- vs oligo- vs poly-articular?
- Systemically unwell / red flags?
• Yes → urgent labs, imaging, paediatric admission. - Initial tests in primary care (if stable): FBE + film, ESR/CRP, U&E, Ca/PO₄/ALP, ANA ± HLA-B27, plain radiograph, ultrasound.
- Refer early to orthopaedics (suspected SUFE, septic joint), oncology/haematology (abnormal bloods), or rheumatology (persistent swelling > 6 weeks, positive auto-antibodies).
Bottom line: Most joint pain in children is benign or post-infectious, but never miss septic arthritis, malignancy or SUFE. A systematic ARTHRITIS checklist, coupled with age-specific red-flag signs and early imaging/labs, keeps your differential broad while honing in on the dangerous few.