What are the most important causes of limping in a child by age group?

Age is the key filter. In children under three years, developmental dysplasia of the hip, occult toddler's fracture (especially of the tibia), Perthes disease, and septic arthritis are the priority diagnoses. In children aged four to ten years, transient synovitis is the most common cause, followed by Perthes disease (typically four to eight years, boys), Legg-Calvé-Perthes disease, and septic arthritis. In adolescents, slipped upper femoral epiphysis is the must-not-miss diagnosis — it presents in overweight boys aged ten to fifteen years with a hip or groin ache and an externally rotated limb. Bone tumours and leukaemia are rare but can present at any age.

How do I tell the difference between transient synovitis and septic arthritis of the hip?

The Kocher criteria give a probability estimate. Each of four factors scores one point: fever above 38.5 degrees Celsius, non-weight-bearing, white blood cell count above 12,000 per microlitre, and ESR above 40 mm per hour (CRP above 20 mg per litre adds discrimination per Caird 2006). A child with zero or one factor has less than three per cent probability of septic arthritis and can be managed as probable transient synovitis with observation. Two or three factors carry 40–93 per cent probability and warrant urgent orthopaedic review; four factors carries over 99 per cent probability and requires emergency joint washout. When in doubt, treat as septic arthritis — a missed septic joint causes permanent damage.

What is slipped upper femoral epiphysis and why is it urgent?

Slipped upper femoral epiphysis (SUFE) is a displacement of the femoral head through the growth plate, occurring most commonly in overweight boys aged ten to fifteen years. The key clinical clue is a hip or groin pain that radiates to the thigh or knee — many children with SUFE present with knee pain and are initially investigated there, missing the hip. The leg rests in external rotation and the child cannot internally rotate the hip. An anterior-posterior hip X-ray may appear normal; the frog-leg lateral view shows posterior displacement of the head. SUFE requires immediate non-weight-bearing and urgent orthopaedic referral for surgical pinning, because continued weight-bearing dramatically increases the risk of avascular necrosis of the femoral head.

What is Perthes disease?

Perthes disease (Legg-Calvé-Perthes disease) is avascular necrosis of the femoral head in children, typically occurring insidiously in boys aged four to eight years. Unlike septic arthritis and SUFE, the onset is gradual — a child who has been limping for weeks without a clear precipitant. The affected hip has restricted internal rotation and abduction. Diagnosis is by plain X-ray (irregular femoral head, sclerosis, crescent sign) followed by MRI for staging. Management ranges from observation for younger children with mild involvement to bracing, physiotherapy, and surgical containment procedures for older children or severe disease, coordinated by paediatric orthopaedics.

When does a limping child need to go to the emergency department today?

Send the child to the emergency department on the same day for: fever with hip pain and restricted movement (septic arthritis until proven otherwise), a child who is completely non-weight-bearing or screaming with passive movement, suspected slipped upper femoral epiphysis (external rotation deformity, adolescent with hip or knee pain), suspected fracture or non-accidental injury, bone pain with bruising or systemic symptoms suggesting malignancy (leukaemia), or acute rheumatic fever in an Aboriginal or Torres Strait Islander child with fever and joint pain. Transient synovitis in a well-looking, afebrile, partially weight-bearing child with a normal inflammatory screen can be managed in the community with a clear safety-net plan and review in 24–48 hours.

What blood tests and imaging are needed for a limping child?

For any limping child without an obvious benign cause, request a FBC, ESR (or CRP), and plain X-rays of the hip (AP and frog-leg lateral — do not accept AP alone for adolescents). In children with fever, add blood cultures before any antibiotic. If septic arthritis is suspected, ultrasound of the hip looking for a joint effusion is the next step — ultrasound cannot distinguish septic arthritis from transient synovitis in the majority of cases, but the absence of an effusion makes septic arthritis unlikely. Bone scintigraphy or MRI is reserved for cases with high suspicion and normal plain X-rays, for occult fracture, or for staging Perthes disease.

Paediatric limp

Limping child: differential diagnosis and red flags in AU general practice

By Dr HB Lo, FACRRM Reviewed 30 September 2026 12 min read

A limping child requires systematic assessment: the differential ranges from benign (transient synovitis) to limb-threatening (septic arthritis, SUFE) and life-threatening (leukaemia). Age guides the differential — toddlers: DDH, occult fracture; school-age: transient synovitis, Perthes; adolescents: SUFE.

Critical diagnoses require immediate action: septic arthritis needs Kocher criteria assessment; SUFE needs a frog-leg lateral X-ray and immediate non-weight-bearing. Acute rheumatic fever is a priority in Aboriginal and Torres Strait Islander children.

A child who limps walks into most general practice consultations at least once a year. The cause is usually benign, but the consequences of missing the dangerous diagnoses — septic arthritis, slipped upper femoral epiphysis, acute rheumatic fever, or a bone tumour — are severe and often irreversible. A systematic, age-stratified approach keeps the assessment efficient without missing the red flags.

A. Core clinical — the AU general-practice framework

Age-stratified differential diagnosis

Age is the most powerful organising principle in limping children, because different pathological processes dominate at different stages of skeletal development (RCH Melbourne CPG — The limping child).

Under 3 years:

Developmental dysplasia of the hip (DDH) — missed on neonatal screening; presents with Trendelenburg gait, leg length discrepancy, restricted abduction
Toddler’s fracture — spiral fracture of the tibial shaft from a rotational fall; the child walks on the foot with pain but X-ray may be normal initially; treat as a fracture clinically and reimage at 10–14 days if negative
Septic arthritis / osteomyelitis — at any age; fever, pseudoparalysis, refusal to weight-bear; emergency
Non-accidental injury — multiple fractures at different healing stages; long-bone fractures in non-ambulant infants; mandatory notification threshold is low

4–10 years:

Transient synovitis — the most common cause of acute hip pain in this age group; afebrile or mildly febrile, partially weight-bearing, self-limiting (2–6 weeks); diagnosis of exclusion after septic arthritis is excluded
Perthes disease (Legg-Calvé-Perthes) — avascular necrosis of the femoral head; insidious onset, typically boys aged 4–8 years, restricted internal rotation and abduction; diagnosis by plain X-ray then MRI for staging
Septic arthritis / osteomyelitis — see urgent section below; exclude at every presentation
Juvenile idiopathic arthritis (JIA) — morning stiffness, multiple joint involvement, systemic features; chronic course
Leukaemia and bone tumours — bone pain, night pain, bruising, pallor, lymphadenopathy, systemic symptoms; any suspicion requires FBC and urgent paediatric review
Acute rheumatic fever (ARF) — particularly in Aboriginal and Torres Strait Islander children; migratory polyarthritis, fever, carditis; streptococcal trigger; see Section E

10–16 years (adolescents):

Slipped upper femoral epiphysis (SUFE) — displacement of the femoral head through the growth plate; obese boys most commonly; must not miss; see below
Osgood-Schlatter disease — tibial tuberosity apophysitis; anterior knee pain with a bony prominence, worsened by activity; benign; physiotherapy and load management
Stress fracture — overuse in active adolescents; tibia and femur most common; plain X-ray often normal early; bone scan or MRI confirms
Avascular necrosis — SUFE complication, sickle cell disease, steroid use; MRI-diagnosed
Malignancy — Ewing’s sarcoma, osteosarcoma peak in adolescence; nocturnal bone pain, soft tissue swelling, systemic symptoms; urgent plain X-ray and referral

The two must-not-miss diagnoses

Septic arthritis: bacterial infection of a joint causes permanent cartilage destruction if not drained within hours. The Kocher criteria (J Bone Joint Surg Am 1999) stratify the probability of septic arthritis versus transient synovitis in a child with a hip effusion. Each of four variables scores one point:

Fever above 38.5°C
Non-weight-bearing
ESR above 40 mm/hour
WBC above 12,000/µL

Caird et al (J Bone Joint Surg Am 2006) added CRP above 20 mg/L as a fifth discriminator. Probability of septic arthritis: 0 factors <3%, 1 factor ~3%, 2 factors ~40%, 3 factors ~93%, 4 factors >99%. A score of two or more warrants urgent orthopaedic review; do not wait for blood culture results.

Slipped upper femoral epiphysis (SUFE): displacement of the femoral head through the open growth plate at the proximal femur, occurring in obese adolescents (boys more than girls, typically aged 10–15 years). The classic presentation is groin or hip pain, but approximately 23 per cent present with isolated knee pain due to referred pain along the obturator nerve distribution — this is the most common reason for diagnostic delay. The hip rests in external rotation and cannot be internally rotated. An AP hip X-ray alone is insufficient — the frog-leg lateral view is mandatory because early posterior displacement of the femoral head is visible only on the lateral projection. On identifying SUFE: make the child non-weight-bearing immediately and arrange same-day orthopaedic referral for urgent surgical pinning. Continued weight-bearing markedly increases the risk of complete displacement and avascular necrosis.

History

Cover:

Onset: sudden vs insidious (sudden favours trauma, sepsis; insidious favours Perthes, tumour, JIA)
Localisation: hip, knee, or thigh pain; referred hip pain commonly presents as knee pain
Fever, constitutional symptoms, weight loss, night pain (all raise concern for infection or malignancy)
Trauma: mechanism, timing, plausibility — if trauma is implicated in a pre-ambulant infant, non-accidental injury is on the differential
Activity levels and sport: overuse injury in active adolescents
Prior similar episodes: recurrent transient synovitis is common; SUFE can present with prior vague hip ache
Relevant medical history: sickle cell disease, immunosuppression, recent infection (streptococcal pharyngitis preceding ARF by 2–6 weeks), recent joint injection or surgery
ATSI background: ARF risk; rheumatic heart disease surveillance; Aboriginal Medical Service engagement

Examination

Gait observation before touching the child — antalgic (short stance phase on affected side), Trendelenburg (trunk sway over affected hip, DDH or proximal muscle weakness), toe-walking, circumduction
Lower limb alignment: leg length, rotational profile, foot alignment
Hip examination: flexion, extension, internal and external rotation, abduction, adduction — internal rotation loss is the most sensitive sign for hip pathology. The FABER test (Flexion, ABduction, External Rotation) stresses the hip joint. In SUFE, the hip automatically externally rotates with passive flexion (Drehmann sign)
Joint examination: effusion, warmth, tenderness, range of motion in the hip, knee, ankle; tenderness over bone or apophysis
Spine: scoliosis, sacroiliac tenderness
Systemic examination: lymphadenopathy, hepatosplenomegaly, rash (rheumatic disease, leukaemia), heart murmur (ARF carditis), pallor
Skin: bruising pattern (non-accidental injury); café-au-lait spots (neurofibromatosis); petechiae (leukaemia, HSP)

Investigations

First-line for all unexplained limp:

Plain X-rays — AP and frog-leg lateral of the hip; do not accept AP alone for adolescents where SUFE is in the differential. Knee X-ray if knee pain predominates. X-rays may be normal in Perthes early, osteomyelitis, and stress fracture
FBC (MBS 65070) — leukaemia (blast cells on film), anaemia (sickle cell, leukaemia), leucocytosis (infection)
ESR and CRP (MBS 66603) — Kocher criteria; baseline for monitoring JIA
Blood cultures (in febrile child before any antibiotics): two sets from separate sites

Second-line / targeted:

Hip ultrasound (MBS 55036) — detects joint effusion; guides aspiration for cell count, Gram stain, and culture; cannot distinguish septic from aseptic effusion in most cases
MRI hip / pelvis — early Perthes, occult fracture, osteomyelitis (ring-enhancing marrow oedema), stress fracture, soft-tissue tumours
Bone scintigraphy — occult fracture, multifocal osteomyelitis, AVN
Antistreptolysin-O titre (ASOT) and anti-DNase-B — ARF diagnosis (streptococcal serology)
ANA, rheumatoid factor, HLA-B27 — JIA and seronegative arthropathy workup (paediatric rheumatology-led)
Peripheral blood film — manual film review for blast cells if leukaemia is possible; do not rely on automated differential alone

B. Evidence appraisal

Kocher criteria are the most rigorously validated clinical decision tool for distinguishing septic arthritis from transient synovitis in the paediatric hip. The original Kocher et al 1999 derivation cohort yielded predicted probabilities that have been partially validated — though Caird et al 2006 and Luhmann et al 2004 found that the exact probability figures do not replicate perfectly across institutions (different microorganism profiles, different CRP cut-offs), meaning the Kocher score should guide threshold-setting rather than be used as an exact probability calculator. The practical rule from Australian and international paediatric orthopaedic practice: a score of two or above mandates same-day orthopaedic consultation; a score of zero or one in an otherwise well-looking, partially weight-bearing, afebrile child can be observed as transient synovitis with close follow-up.

Transient synovitis is a diagnosis of exclusion — it cannot be diagnosed with certainty in the acute setting. The correct framing for parents is: “The most likely cause is a self-limiting hip inflammation, but we are monitoring closely to make sure it is not an infection.” Resolution within two to six weeks with rest and analgesia is the expected course.

SUFE management: the evidence base consistently supports immediate surgical stabilisation (in situ percutaneous pinning) as the standard of care. Weight-bearing before pinning increases the risk of complete slip and avascular necrosis. There is no role for non-operative management except in specific institutional research protocols.

ARF in ATSI communities: the Australian guideline (National Heart Foundation of Australia and CSANZ 2020) sets lower diagnostic thresholds for ARF in ATSI children because of the high background incidence. Echocardiography is recommended in all suspected ARF cases to detect subclinical carditis, which is present in approximately 50 per cent of first episodes and changes long-term management. The ATSI-specific diagnostic criteria allow diagnosis on less stringent clinical grounds given the population prevalence.

C. Australian operations — MBS, PBS, referral pathways

MBS items (MBS Online): GP consultation item 23/36/44; plain X-ray lower limb item 57700 range; hip ultrasound item 55036; FBC item 65070; ESR/CRP item 66603; blood cultures item 73546. ATSI annual health check item 715 for systematic musculoskeletal and ARF surveillance in Aboriginal and Torres Strait Islander children.

Referral pathways:

Scenario	Referral	Urgency
Fever + hip pain + restricted movement; Kocher score ≥2	Paediatric emergency or orthopaedics	Same hour
SUFE identified on X-ray	Orthopaedics + non-weight-bearing	Same day
Non-weight-bearing without clear diagnosis	Paediatric emergency	Same day
Suspected malignancy (night pain, bone swelling, blast cells)	Paediatric oncology	Same day
Suspected ARF	Paediatric emergency + cardiology	Same day
Suspected non-accidental injury	Paediatric emergency + child protection	Same day (mandatory report)
Probable transient synovitis, Kocher 0–1, well-looking	Rest + analgesia + review in 24–48 h; orthopaedics if no improvement at 7 days	Routine with safety-net
Suspected Perthes disease	Paediatric orthopaedics	Within 2 weeks
JIA suspected	Paediatric rheumatology	Within 4 weeks

PBS medications (PBS Online):

Ibuprofen (PBS general listing) — first-line analgesia and anti-inflammatory for transient synovitis; dose per weight per AMH
Paracetamol (PBS general listing) — adjunctive analgesia
Benzathine benzylpenicillin G (Bicillin LA) — PBS Authority Required for ARF prophylaxis in ATSI children and those with proven first episode; 1.2 million units IM every 28 days (monthly); given at ACCHS or GP under safe injecting protocol; reduces recurrent ARF and prevents progressive rheumatic heart disease
IV antibiotics for septic arthritis (hospital-administered): flucloxacillin plus gentamicin or cefazolin per eTG antibiotic guidelines; duration guided by clinical response and CRP trend

Mandatory reporting: suspected non-accidental injury triggers mandatory notification to the state child protection authority. Document the factual basis for the concern separately from the clinical notes.

D. Integrative and lifestyle considerations

Rest and activity modification are the cornerstone of management for transient synovitis, Osgood-Schlatter disease, and stress fracture. The evidence base for the specific duration of rest in transient synovitis is limited, but symptom-guided return to activity (when the child is pain-free and has full range of motion) is the standard approach.

Analgesia for transient synovitis: weight-based ibuprofen AMH or paracetamol provides adequate symptom relief and may hasten resolution of inflammation in transient synovitis. There is no evidence that corticosteroids alter the course or recurrence rate of transient synovitis.

Load management for Osgood-Schlatter and stress fracture: reduction of impact loading while maintaining cardiovascular fitness (swimming, cycling); graduated return to sport over six to twelve weeks; involvement of a sports physiotherapist improves adherence and outcomes.

Physiotherapy is the primary treatment for Perthes disease in mild to moderate presentations, alongside activity modification and pain management. The goal is maintaining hip range of motion and muscular strength while the avascular femoral head revascularises over twelve to twenty-four months.

Nutrition and weight management for SUFE: SUFE occurs almost exclusively in overweight and obese adolescents. After surgical stabilisation, structured nutritional assessment and weight management support form part of the ongoing care plan. Referral to a paediatric dietitian under a GPCCMP (items 965/967 and allied health items) is appropriate.

E. Special populations

Aboriginal and Torres Strait Islander children: acute rheumatic fever (ARF) is a priority diagnosis that must be considered in any Aboriginal or Torres Strait Islander child with fever and joint pain. ARF results from an immune response to group A streptococcal pharyngitis and causes migratory polyarthritis, carditis, Sydenham’s chorea, subcutaneous nodules, and erythema marginatum. The National Heart Foundation of Australia 2020 guideline sets lower diagnostic thresholds for ATSI children. Echocardiography is recommended for all suspected cases. Secondary prophylaxis with monthly benzathine benzylpenicillin is the cornerstone of prevention, administered at ACCHS or GP clinics aligned with Closing the Gap health targets. Engagement with the local ACCHS and ATSI health worker is essential for adherence and culturally safe follow-up.

Infants and toddlers: limping or gait abnormality in a non-ambulant or recently ambulant child always raises the question of non-accidental injury alongside organic causes. The threshold for imaging and child protection notification should be low. Metaphyseal corner fractures, posterior rib fractures, and bilateral long-bone fractures in non-ambulant infants are highly specific for inflicted injury.

Immunocompromised children: septic arthritis and osteomyelitis can present atypically — without fever or leucocytosis — in children on immunosuppressive therapy (chemotherapy, corticosteroids, biologics). Clinical suspicion must remain high and imaging and joint aspiration are required even when inflammatory markers are normal.

Children with sickle cell disease: vaso-occlusive crises can cause acute bone pain mimicking infection. Differentiating bone infarction from osteomyelitis is clinically challenging — MRI and joint aspiration are often required. Salmonella and Staphylococcus aureus are the dominant organisms in sickle cell osteomyelitis.

When to escalate

Same-hour escalation to the emergency department for: Kocher score two or above; complete non-weight-bearing without clear benign explanation; fever with bone or joint pain and no clear diagnosis; SUFE identified on X-ray; suspected malignancy (night pain, systemic symptoms, abnormal FBC); suspected ARF in an ATSI child; suspected non-accidental injury.

Urgent orthopaedic consultation on the same day for any confirmed SUFE — do not send the child home to return the following week.

Observation and 24–48 hour review in the community is appropriate only for a well-appearing, afebrile, partially weight-bearing child with Kocher score of 0–1 and a normal FBC, with clear safety-net instructions to return if the child develops fever, stops weight-bearing, or does not improve within 48 hours.

What this article is and is not

This article summarises Australian and international evidence-based guidelines on the limping child to support informed conversations between families and health professionals. It is for educational purposes and does not constitute medical advice for any individual child. A limping child should always be assessed by a qualified health professional who can apply age-appropriate clinical assessment, arrange imaging, and determine the urgency of further specialist involvement. Families who are concerned about a limping child should contact their GP on the same day, or go to the emergency department if the child has a fever, refuses to weight-bear, or appears unwell.

Sources cited

RCH Melbourne CPG — The limping child
eTG complete — Paediatric musculoskeletal conditions
RACGP — The limping child in general practice
NICE NG143 — Fever in under 5s
Kocher MS et al. Differentiating septic arthritis from transient synovitis. J Bone Joint Surg Am 1999
Caird MS et al. Factors distinguishing septic arthritis from transient synovitis. J Bone Joint Surg Am 2006
Luhmann SJ et al. Differentiating transient synovitis and septic arthritis. J Pediatr Orthop 2004
National Heart Foundation of Australia — Acute rheumatic fever and rheumatic heart disease guideline 2020
Closing the Gap — National Agreement on Closing the Gap
Australian Medicines Handbook — analgesia, antibiotics
MBS Online — items 23, 36, 44, 55036, 57700, 65070, 66603, 73546, 715, 965, 967
PBS Online — benzathine benzylpenicillin, ibuprofen, paracetamol

Frequently asked questions

What are the most important causes of limping in a child by age group?

Age is the key filter. In children under three years, developmental dysplasia of the hip, occult toddler's fracture (especially of the tibia), Perthes disease, and septic arthritis are the priority diagnoses. In children aged four to ten years, transient synovitis is the most common cause, followed by Perthes disease (typically four to eight years, boys), Legg-Calvé-Perthes disease, and septic arthritis. In adolescents, slipped upper femoral epiphysis is the must-not-miss diagnosis — it presents in overweight boys aged ten to fifteen years with a hip or groin ache and an externally rotated limb. Bone tumours and leukaemia are rare but can present at any age.
How do I tell the difference between transient synovitis and septic arthritis of the hip?

The Kocher criteria give a probability estimate. Each of four factors scores one point: fever above 38.5 degrees Celsius, non-weight-bearing, white blood cell count above 12,000 per microlitre, and ESR above 40 mm per hour (CRP above 20 mg per litre adds discrimination per Caird 2006). A child with zero or one factor has less than three per cent probability of septic arthritis and can be managed as probable transient synovitis with observation. Two or three factors carry 40–93 per cent probability and warrant urgent orthopaedic review; four factors carries over 99 per cent probability and requires emergency joint washout. When in doubt, treat as septic arthritis — a missed septic joint causes permanent damage.
What is slipped upper femoral epiphysis and why is it urgent?

Slipped upper femoral epiphysis (SUFE) is a displacement of the femoral head through the growth plate, occurring most commonly in overweight boys aged ten to fifteen years. The key clinical clue is a hip or groin pain that radiates to the thigh or knee — many children with SUFE present with knee pain and are initially investigated there, missing the hip. The leg rests in external rotation and the child cannot internally rotate the hip. An anterior-posterior hip X-ray may appear normal; the frog-leg lateral view shows posterior displacement of the head. SUFE requires immediate non-weight-bearing and urgent orthopaedic referral for surgical pinning, because continued weight-bearing dramatically increases the risk of avascular necrosis of the femoral head.
What is Perthes disease?

Perthes disease (Legg-Calvé-Perthes disease) is avascular necrosis of the femoral head in children, typically occurring insidiously in boys aged four to eight years. Unlike septic arthritis and SUFE, the onset is gradual — a child who has been limping for weeks without a clear precipitant. The affected hip has restricted internal rotation and abduction. Diagnosis is by plain X-ray (irregular femoral head, sclerosis, crescent sign) followed by MRI for staging. Management ranges from observation for younger children with mild involvement to bracing, physiotherapy, and surgical containment procedures for older children or severe disease, coordinated by paediatric orthopaedics.
When does a limping child need to go to the emergency department today?

Send the child to the emergency department on the same day for: fever with hip pain and restricted movement (septic arthritis until proven otherwise), a child who is completely non-weight-bearing or screaming with passive movement, suspected slipped upper femoral epiphysis (external rotation deformity, adolescent with hip or knee pain), suspected fracture or non-accidental injury, bone pain with bruising or systemic symptoms suggesting malignancy (leukaemia), or acute rheumatic fever in an Aboriginal or Torres Strait Islander child with fever and joint pain. Transient synovitis in a well-looking, afebrile, partially weight-bearing child with a normal inflammatory screen can be managed in the community with a clear safety-net plan and review in 24–48 hours.
What blood tests and imaging are needed for a limping child?

For any limping child without an obvious benign cause, request a FBC, ESR (or CRP), and plain X-rays of the hip (AP and frog-leg lateral — do not accept AP alone for adolescents). In children with fever, add blood cultures before any antibiotic. If septic arthritis is suspected, ultrasound of the hip looking for a joint effusion is the next step — ultrasound cannot distinguish septic arthritis from transient synovitis in the majority of cases, but the absence of an effusion makes septic arthritis unlikely. Bone scintigraphy or MRI is reserved for cases with high suspicion and normal plain X-rays, for occult fracture, or for staging Perthes disease.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.