Growing Pains

Growing pains are recurrent, benign, non-articular lower limb pains in otherwise healthy children, occurring in the late afternoon, evening or night, with no objective abnormality. Also termed benign idiopathic nocturnal limb pains of childhood.

• Prevalence 10 to 37 percent of children. Two age peaks: 3 to 5 years and 8 to 12 years.
• Cause unknown; proposed factors include muscle fatigue after strenuous daytime activity, a lowered pain threshold, reduced bone strength or bone density, vitamin D deficiency, joint hypermobility, flat feet, biomechanical stress, psychological and family factors (the family has a history in many). It does not relate to growth spurts.
• It is a diagnosis of exclusion. Pain in a joint, pain in the morning, limp, or systemic symptoms make the diagnosis untenable.
• Prognosis: pain resolves spontaneously within months to a few years, with no sequelae.

• Bilateral, poorly localised deep aching or cramping pain in the thighs, calves, shins or behind the knees (muscles, not joints), episodic (days or weeks apart), starting in the evening or waking the child from sleep, lasting 10 to 30 minutes up to a few hours, relieved by massage, warmth, analgesia, or comfort.
• Gone by morning and the child plays normally the next day, no limp, no restriction in activity, normal gait, and often worse after a day of strenuous activity.
• Examination is entirely normal: full range of joint movement, no swelling, warmth, tenderness, erythema, no muscle wasting, normal growth and gait, no rash, normal neurological examination, normal spine, hips and feet. Hypermobility (Beighton score) and flat feet may be present.
• Red flags (consider other diagnoses): unilateral pain, persistent daytime pain, pain on waking or morning stiffness, limp or refusal to walk, localised bony or joint tenderness, joint swelling, redness or warmth, fever, weight loss, night sweats, malaise, back pain, rash, bruising or bleeding, pallor, lymphadenopathy, hepatosplenomegaly, limited motion, muscle weakness, leg length discrepancy, pain that escalates, age under 3 or over 12 years, family history of rheumatic disease.
• Differentials: juvenile idiopathic arthritis, leukaemia (bone pain, pallor, bruising), osteoid osteoma (night pain relieved by NSAIDs), osteomyelitis, Perthes disease and slipped capital femoral epiphysis (hip pain referred to knee), vitamin D deficiency rickets, sickle cell crises, restless legs, muscular dystrophy, hypermobility syndrome, trauma, non-accidental injury.

• Clinical: typical history with a normal examination. No investigations are needed.
• If any atypical or red flag feature: full blood count with film, ESR, CRP, LDH, uric acid, calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D, creatine kinase, X-ray of the affected limb, and ultrasound or MRI when focal; antinuclear antibody and rheumatoid factor are not helpful in the absence of arthritis.
• Review in 4 to 6 weeks if uncertain.

• Reassurance for the parents and child that this is a benign, common, self-limiting condition.
• Comfort measures at the time of pain: leg massage, warm bath or heat pack, gentle stretching, distraction and comfort.
• Analgesia as needed: paracetamol 15 mg/kg orally (maximum 4 doses in 24 hours) or ibuprofen 5 to 10 mg/kg orally with food (maximum 30 mg/kg per day), given at the onset of pain or at bedtime on days with an episode; avoid regular use.
• Daily leg stretches (calf and hamstring) for 10 minutes, night time and morning, can reduce the frequency.
• Correct predisposing factors: supportive footwear or orthotics for symptomatic flat feet, vitamin D replacement if levels are low (cholecalciferol 1000 to 2000 IU daily for 8 to 12 weeks for deficiency, then 400 to 600 IU daily), maintain a balanced diet, adequate sleep, moderate daytime activity, manage anxiety.
• Do not restrict normal activity or sport.
• Follow up in 4 to 6 weeks; re-evaluate and investigate if new red flags develop or pain persists beyond 3 months.