Growing Pains

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Differential Diagnosis

Paediatric Leg Pain Differential Diagnosis

• Infection (viral myositis, TB, syphilis, trichinosis, poststreptococcal polymyalgia, osteomyelitis, septic arthritis)
• Metabolic (osteomalacia, rickets, hypervitaminosis A, scurvy, Gaucher disease, renal tubular acidosis, metabolic myopathy)
• Tumours (leukaemia, lymphoma, spinal cord tumours, bone tumours, metastases)
• Trauma (fractures, stress fractures, overuse syndromes)
• Miscellaneous (hypermobility syndrome, rheumatologic disease, somatisation, fibromyalgia, intermittent nocturnal leg cramps, CRPS, restless legs, sickle cell anaemia, osteonecrosis, SUFE, school phobia, patellofemoral pain syndrome)

There is an extensive list of differentials for paediatric lower limb pain. Growing pains can usually be differentiated from other conditions by a normal physical examination, lack of constitutional symptoms, and generally no limitations of activities. In some cases blood tests and radiographs are necessary.

Trauma: cardinal features of stress fractures and overuse syndromes in general are localised pain of insidious onset. The pain increases with activity and there is focal tenderness

Bone tumours and leukaemia: pain is usually at night which can make it difficult to distinguish from growing pains. However the pain is usually unilateral rather than bilateral in growing pains. There may be a palpable mass and focal tenderness. The pattern of pain in primary bone tumours such as Ewing sarcoma and osteoid osteomas is initially intermittent that increases in severity over time. In Ewing sarcoma the pain may disappear for long stretches of time.

Infection: The child may initially have a low-grade fever, malaise, irritability, decreased appetite, or decreased activity. With worsening of the infection there may be focal pain, reduced activity, and features on exam of infection.

Osteonecrosis: Perthes disease of the hip is the classic condition here. The pain is in the hip and insidious in onset. The child may have a limp or Trendelenburg gait.

Metabolic disease: In rickets there may be delayed fontanelle closure, parietal and frontal bossing, enlargement of the costochondral junction, widening of the wrist, and lateral bowing of the femur and tibia. The diagnosis can be made on radiographs along with elevated ALP.

Rheumatologic disorders: In juvenile idiopathic arthritis the child may have a limp and overt inflammation in one or more joints.

Treatment

Reassure the child and caregiver about the benign nature of the condition. The child should continue usual activities. Reducing or ceasing physical activities is not helpful and can lead to hypervigilence.

For acute pain consider massage, paracetamol, ibuprofen, and heat. In children where increased physical activity tends to bring about a cluster of painful nights they can consider prophylactic ibuprofen at bedtime following a day of increased activity. This can also be considered to break the cycle of repeated painful nights. In some cases ibuprofen may be too short acting and naproxen can be used which has a longer half life.

Children with low vitamin D levels should take vitamin D and calcium supplements.

Muscle stretching can help with the parent assisting. In one unblinded study, children who stretched twice daily had an average of zero episodes a month compared to one to two episodes a month in the control group. The stretching group also had more rapid resolution of symptoms.

• Quadriceps: child prone, flex heel to buttock and hold, lift thigh off table to stretch
• Hamstrings: child supine, lift leg by heel, hold knee straight, flex hip to stretch
• Calf: child prone, knee flexed to 90 degrees, push foot down to stretch. child supine, knee straight, push foot up to stretch.

In children with hypermobility, food malalignment, genu valgum, or poor balance, physical therapy and/or custom molded orthotic to control for overpronation may be helpful.