What is the diagnosis and management for a 21-month-old female with no recent history of trauma, presenting with lower extremity shaking, inability to walk more than 4-5 steps, and refusal to walk, resorting to crawling, for 3 days?

Acute Refusal to Walk in a Toddler: Differential Diagnosis and Management

This 21-month-old with acute onset refusal to walk, lower extremity shaking, and preference for crawling most likely has either an occult calcaneus fracture, toddler's fracture, or acute inflammatory myopathy, and requires immediate weight-bearing assessment and targeted imaging.

Immediate Clinical Assessment

The first priority is determining whether this child can bear weight at all, as inability to take 4 steps strongly suggests fracture even without recalled trauma 1. Examine for:

• Point tenderness over the calcaneus bilaterally - this is the critical finding that mandates radiographic evaluation per Ottawa Ankle Rules (applicable to children ≥5 years, but clinical judgment applies to younger children) 1
• Visible heel swelling, ecchymosis, or deformity - particularly concerning for displaced fractures 1
• Gowers' sign - difficulty rising from floor with hand-walking up the legs, which would suggest proximal muscle weakness rather than skeletal injury 2
• Asymmetric weakness - unilateral findings point toward structural injury; bilateral proximal weakness suggests myopathy 3

Diagnostic Approach

Initial Imaging Strategy

Order standard three-view foot radiographs (AP, lateral, oblique) plus axial Harris-Beath view for both feet, as standard radiographs have only 87% sensitivity for calcaneal fractures 1. The "no history of trauma" is unreliable in toddlers who may have unwitnessed falls or minor injuries that parents dismiss 1.

If radiographs are negative but clinical suspicion remains high (persistent refusal to bear weight, point tenderness), proceed immediately to CT without IV contrast rather than waiting, as occult fractures are common in this age group 1.

Laboratory Evaluation

Obtain simultaneously with imaging:

• Creatine kinase (CK) - markedly elevated CK (often >1000 U/L) suggests myopathy 2
• Thyroid function tests - hyperthyroidism can present as isolated proximal myopathy in children, though rare 3
• Complete blood count with differential - to assess for inflammatory or infectious processes

Differential Diagnosis Framework

Most Likely: Occult Calcaneus Fracture

The triad of acute onset, refusal to walk, and lower extremity "shaking" (likely pain-related tremor with attempted weight-bearing) strongly suggests fracture 1. Toddlers frequently sustain calcaneal fractures from falls that parents consider trivial - jumping off furniture, playground equipment, or even stepping down from a curb 1.

Alternative: Toddler's Fracture (Tibial Spiral Fracture)

Non-displaced spiral fractures of the tibia are notoriously difficult to see on initial radiographs and present identically with refusal to walk 1. If calcaneal imaging is negative, obtain tibia/fibula radiographs bilaterally.

Less Likely but Critical: Acute Myopathy

The "shaking" could represent true tremor from muscle weakness rather than pain. Positive Gowers' sign with bilateral proximal weakness and markedly elevated CK would confirm myopathy 2, 3. However, myopathy typically develops over weeks, not 3 days.

Rare but Must Exclude: Guillain-Barré Syndrome (GBS)

Young children (<6 years) can present atypically with refusal to bear weight, irritability, and unsteady gait rather than classic ascending paralysis 2. However, GBS would show:

• Absent or decreased reflexes (critical distinguishing feature) 2
• Progressive symptoms beyond 3 days 2
• Bilateral symmetric involvement 2

Management Algorithm

If Fracture Confirmed:

1. Immediate orthopedic consultation - all confirmed calcaneal fractures in children warrant specialist evaluation 1
2. Immobilize in posterior splint pending orthopedic assessment 1
3. Non-weight-bearing status with crutches or walker (though impractical at 21 months - parents will need to carry child) 1

If Imaging Negative but High Clinical Suspicion:

1. Immobilize anyway - place in walking boot or posterior splint 1
2. Arrange orthopedic follow-up within 48-72 hours for repeat examination and consideration of MRI 1
3. Strict return precautions - if child develops skin changes, increased swelling, or neurologic symptoms, return immediately 1

If Myopathy Suspected (Elevated CK, Gowers' Sign):

1. Urgent neurology consultation - same day if CK >5000 U/L 2
2. Admit for observation if any respiratory muscle involvement suspected 2
3. Genetic testing for Duchenne muscular dystrophy if male, though onset at 21 months would be unusually early 2

If GBS Suspected (Areflexia, Progressive Weakness):

1. Emergency department transfer - GBS is a medical emergency requiring ICU-level monitoring 2
2. Respiratory function monitoring - vital capacity measurements 2
3. Lumbar puncture and nerve conduction studies - but do not delay treatment for testing 2

Critical Pitfalls to Avoid

Do not dismiss "no history of trauma" - toddlers sustain fractures from mechanisms adults would not consider traumatic, and parents often don't witness the injury 1. The 3-day timeline suggests a specific inciting event that may have been forgotten or minimized.

Do not rely solely on initial radiographs - if clinical suspicion exists (point tenderness, refusal to bear weight), proceed to CT or immobilize and follow up closely 1.

Do not miss urgent fracture patterns - tongue-type calcaneal fractures and tuberosity avulsions require intervention within 24 hours to prevent skin necrosis 1.

Do not overlook systemic causes - while fracture is most likely, the bilateral nature and "shaking" warrant at minimum a CK level to exclude myopathy 2, 3.