The limping child

Abnormal gaits

• Antalgic gait – Short stance phase due to pain on weight bearing
• Myopathic gait – aka Trendelenberg or waddling gait
  • Pelvic girdle weakness causes drop in pelvis on contralateral side (Trendelenberg sign)
  • Bilateral weakness causes waddling gait
• Hemiplegic gait
  • Leg in extension with plantarflexion of foot and toes
  • Loss of normal arm swing, circumduction of flexed/adducted/internally rotated upper limb
  • Circumduction of leg due to foot drop

• Diplegic gait
  • Narrow base, dragging both legs and scraping the toes
  • Seen in spasticity of both legs worse than arms (e.g. Cerebral palsy)
• Scissors gait
  • Extreme tightness of hip adductors causes legs to cross midline
• Neuropathic gait (aka equine)
  • Affected leg lifted higher due to foot drop
  • Bilateral in peripheral neuropathies e.g. Charcot-Marie-Tooth

• Parkinsonian gait
  • Shuffling gait
• Choreiform gait
  • Irregular, jerky, involuntary movements in all extremities
• Ataxic gait
  • Titubation or swaggering from side to side and unable to walk in straight line
• Sensory gait
  • Foot slapped hard on ground to provide proprioceptive input
  • Worse in the dark
  • Resembles ataxic gait if severe

Differential by age

All ages

Septic arthritis, discitis, viral myositis, trauma, NAI, bone tumors, ALL, Rheumatological, Reactive arthritis, Intra-abdominal, inguinal/scrotal pathology, vasculitis/serum sickness, functional limp

Examination

• Walk with minimal clothing
• Careful active and passive joint examination including back and full hip examination
• Look for wasting and leg length discrepancy
• Trendelenberg test – stand on one leg for 30 sec
• Look for muscle spasm and tightness
• Exaggerated lordosis in discitis

Red flags

• Child <3yo refusing to weight bear
• Fever or systemic illness in association with new limp
• Child >9yo with pain or restricted hip movement

Clinical tips

• Unremitting pain or night pain suggests sepsis or tumor
• Leg pain is the presenting symptom in 10% of leukaemia
• Always consider NAI

Less common causes of limp to consider

• Fasciitis/apophysitis
• Discitis
• Duchenne MD
• Freiberg disease
• Haemophilia
• Juvenile RA
• Osgood-Schlatter
• Osteochondritis dissecans
• Rickets
• Sever disease
• Sickle cell disease
• Testicular torsion
• ALL, neuroblastoma, Ewing sarcoma, osteosarcoma

Refusal to weight bear

• Careful exam of back/hips/scrotum/knees/ankles
• Transient synovitis is a diagnosis of exclusion under 2yo when septic arthritis should be assumed no matter how mild the presentation
• Pain from lower back may refer to buttocks and lateral thigh
• Pain from hip may refer to thigh and knee

Investigations

• Unless suspecting a specific diagnosis, investigations are usually not required in the limping child <3 days duration
• Consider FBC, Chem20, CRP, ESR + x-ray/USS

Toddler fracture

• Subtle undisplaced spiral fracture of tibia
• Bone scan may be required (x-ray very subtle)
• F/u x-ray in 10 days usually shows periosteal reaction
• Treatment (PEMsoft)
  • Immobilisation for 2-3 weeks ONLY if pain at rest
  • Children will limp for 4-8 weeks irrespective of treatment

Septic arthritis

• Joints with intra-articular metaphysis are most vulnerable: Hip, shoulder, elbow, ankle
• 80% lower limb, 2/3 under 3yo
• Knee 40% of cases, hip 20% of cases
• Pain with passive joint movement

Kochers criteria
 

• Specific for distinguishing transient synovitis from septic arthritis in child with hip pain
• Factors
  • Fever >38.5
  • Cannot bear weight
  • ESR >40 in first hour
  • WCC >12
• Probability
  • No factors: <0.2%
  • 1 factor: 3%
  • 2 factors: 40%
  • 3 factors: 93.1%
  • 4 factors: 99.6%

Infectious agents

• 30-40% are culture negative (despite pus in joint)
• BC positive in 40%
• S. aureus is most common
• Group B strep 2^nd most common
• E. coli in newborns
• Kingella kingae in immunocompromised or children <2yo
• N. gonorrhoea <10%
• Salmonella in sickle cell or asplenic children

Ultrasound in septic arthritis

• 95% sensitive for hip effusion
  • Could be septic arthritis, sympathetic effusion from femoral neck osteomyelitis, transient synovitis or haemarthrosis

Septic arthritis of the hip

• Usually <5yo
• Assume in <2yo with acute hip problem
• Fever in most, hip usually tender with pain on any movement
• Classic hip position is flexion/abduction and external rotation
• Kocher’s criteria (see next)
• Beware the mild symptom pt, no/mild fever in up to 20%

Treatment of septic arthritis

• Joint aspiration prior to antibiotics
• Surgical drainage more likely if MRSA
• Arthroscopy/arthrotomy often used for larger joints
• Hip requires open irrigation
• IV flucloxacillin + Lincomycin if previous nmMRSA, at-risk ethnic group or personal/family hx of boils/furuncles (LCCH)
• IV Cefotaxime +- Lincomycin if not Hib immune and <5yo

Benign acute myositis

• Often epidemic in wintertime due to Influenza
• Usually 2-14yo (average 8yo)
• Influenza B, A, Coxsackie, Echovirus, RSV, adenovirus and HIV
• Suspect if refusal to weight bear or limp days after flu-like illness
  • May be wide-based, stiff-legged or toe-walking
  • Calf pain and tenderness is VERY common
• Elevated CK in 95% of cases to median of 4000
• Usually no myoglobinuria
• Consider metabolic disorder if CK >20 000 or recurrent episodes
• 3% rhabdomyolysis rate – females 4:1
• Should improve spontaneously within 1 week

Perthes disease

• Avascular necrosis of femoral head
• Age 2-12 (majority 4-8yo)
• 20% bilateral

SUFE

• Late childhood/adolescence
• Weight often >90^th centile
• Hip appears externally rotated and shortened
• Internal rotation limited
• May be bilateral

Transient synovitis

• Most common cause in pre-school age
• Usually 3-8yo
• History of recent viral Ix (1-2 weeks)
• Usually able to walk but with pain
• Afebrile and well
• Mild-moderate decrease in hip ROM (especially internal rotation and adduction)
• Typically minimal pain with passive ranging
• Severe limitation of movement suggests septic arthritis

Disposition

• If no specific cause found or suspected transient synovitis
  • Bed rest
  • NSAID +- paracetamol
  • Review with GP within 3 days
  • Return to hospital if febrile, deteriorating
  • If >4 weeks duration, refer to Rheumatology clinic

Last Updated on November 10, 2021 by Andrew Crofton