What are the potential causes and treatment options for leg pain in pediatric patients?

Leg Pain in Pediatric Patients: Diagnostic and Management Approach

Most Common Causes

Trauma and infections are the most common causes of leg pain in children, followed by inflammatory conditions, developmental diagnoses, and overuse injuries. 1

• Nonspecific lower leg and foot pains are frequently underrepresented in the literature but occur commonly in pediatric patients 2
• These pains may be associated with pes planovalgus (flat feet) and often benefit from orthotic intervention 2
• Increased ankle dorsiflexor strength and joint hypermobility are predictive factors for leg pain in children 3
• Increased body weight, waist girth, and BMI are all associated with leg pain 3

Critical Red Flags Requiring Urgent Evaluation

Compartment syndrome, vascular compromise, and open fractures are orthopedic emergencies that must be identified immediately. 1

• Compartment syndrome in children presents with the "three As": analgesia requirement, anxiety, and agitation 1
• Pain out of proportion to injury and progressive swelling in a confined compartment require urgent evaluation 4
• Younger children cannot articulate pain and paresthesia effectively, making behavioral changes critical diagnostic indicators 5
• Inability to bear weight suggests severe injury requiring urgent evaluation 4

Specific Etiologies to Consider

Infectious Causes

• When suspicion is high for infectious etiology, order complete blood count, erythrocyte sedimentation rate, C-reactive protein, and blood cultures 1
• Septic arthritis diagnosis increases with the number of Kocher criteria present: temperature >38.5°C, white blood cell count >12,000/mL, erythrocyte sedimentation rate >40 mm/h, and inability to bear weight 1

Inflammatory/Autoimmune Conditions

• Cramping pain from hypocalcemia should be considered, particularly in patients with known endocrine disorders 2
• Juvenile idiopathic arthritis, often polyarticular and associated with IgA deficiency, can present with leg pain 2
• Laboratory studies are not always definitive for diagnosis of juvenile idiopathic arthritis 1
• Joint swelling, stiffness at rest, or morning stiffness suggests inflammatory arthritis rather than mechanical or benign causes 6

Musculoskeletal Abnormalities

• Scoliosis is common and may be clinically significant, sometimes requiring bracing or spinal surgery 2
• Other skeletal issues include dislocation, clubfoot, patellar abnormalities, polydactyly, hammer toe, and other foot anomalies 2
• Reexamination at 4-5 days post-injury significantly improves diagnostic accuracy for muscle tears, as initial swelling and pain can obscure the true extent of injury 4

Neurologic Causes

• Tethered cord should be considered in patients with bowel and bladder dysfunction or lower limb upper motor neuron signs, especially when a sacral dimple is present 2
• Lumbar spine MRI should be obtained to rule out tethered cord in these cases 2
• Unprovoked seizures and epilepsy occur in up to 15% of patients with certain genetic syndromes 2

Diagnostic Imaging Algorithm

Plain radiographs are the appropriate initial imaging study for leg pain in all pediatric age groups. 6

• MRI has 95% sensitivity and 95% specificity for detecting muscle tears and is particularly useful for suspected complete rupture requiring surgical planning, persistent symptoms, or ruling out complications 4
• MRI without contrast can identify overuse injuries in skeletally immature patients, including soft-tissue and osseous lesions 6
• Ultrasound offers dynamic assessment capability and contralateral comparison without additional cost, making it valuable for soft tissue evaluation 6
• Radionuclide bone imaging is extremely rewarding when history and clinical examination are not specific 7

Physical Examination Essentials

Always examine the joint above and the joint below the area of chief complaint, specifically when evaluating hip and knee pathology. 1

• Palpate for specific areas of tenderness along the tibia, fibula, and foot structures 2
• Assess for pes planovalgus (flat feet) which may contribute to nonspecific leg pain 2
• Evaluate joint hypermobility using standardized scoring systems 3
• Measure ankle dorsiflexion strength as increased strength correlates with leg pain 3

Pharmacological Pain Management

Naproxen is the preferred first-line NSAID over other selective COX-1 or COX-2 inhibitors due to its established efficacy and safety profile in children. 6

• Ibuprofen is an acceptable alternative first-line NSAID, with dosing based on age, weight, and comorbidities 6
• Acetylsalicylic acid is NOT recommended for children due to controversial efficacy, safety concerns, and toxicity risks 6
• Combination therapy with paracetamol enhances NSAID effect for postoperative or acute pain management 6
• Small titrated doses of opiates can be used for severe pain without affecting clinical examination or neurologic assessments 6

Non-Pharmacological Interventions

Cognitive behavioral strategies, distraction, and breathing interventions are very effective in reducing pain and improving compliance. 2, 6

• Parents can function as "coaches" for cognitive behavioral strategies, providing encouragement for coping mechanisms 2
• Massage, heat compresses, ice packs, and repositioning should be considered as adjuncts 2
• Orthotics may benefit patients with pes planovalgus-associated leg pain 2
• Physical, occupational, and speech therapies can help maximize function in patients with underlying developmental conditions 2

When to Refer to Specialist

Refer to pediatric specialist when pain significantly impacts daily functioning or quality of life. 6

• Signs of inflammatory arthritis require immediate rheumatology referral 6
• Acute medication provides insufficient pain relief 6
• Focal neurologic findings, muscle weakness, abnormal deep tendon reflexes, or severe abnormalities in muscle tone require neurologic evaluation and may require brain MRI 2
• Suspected compartment syndrome requires immediate orthopedic consultation 4, 5

Screening Recommendations

Routine scoliosis screening is recommended, with scoliometer and radiography when clinically indicated. 2

• Some sites screen from age 6 years with radiography at 2-year intervals until skeletal maturity 2
• One-time screening for cervical spinal anomalies and instability with radiography including atlas-dens measurements in flexion and extension is recommended around age 4 years 2
• In older children and adolescents with suspected patellar dislocation, radiographs are indicated 2

Common Pitfalls to Avoid

Undertreatment of pain in children is a significant problem; proactive use of appropriate analgesic therapy is essential. 6

• Assuming pain management will mask symptoms or cloud mental status is unfounded; pain medications make children more comfortable and facilitate examination 6
• Missing compartment syndrome by relying solely on traditional "5 Ps" in young children who cannot articulate symptoms—watch for the "three As" instead 5, 1
• Failing to reexamine at 4-5 days post-injury for suspected muscle tears, as initial assessment may be inaccurate 4
• Inadequate trial period for NSAID therapy in inflammatory conditions; at least 8 weeks is required given the time course to response of about 1 month 6
• Overlooking hypocalcemia as a cause of cramping leg pain 2