Correlates and predictors of paediatric leg pain: a case-control study.

Paediatric leg pains, long described as 'growing pains', frequently present to clinicians, are prevalent in early childhood, disrupt sleep, and distress affected children and parents. There are many cited associations, but no defined leg pain sub-types, nor revealed predictive factors. We explored the implicated factors (viz. foot arches, foot strength, joint mobility, vitamin D, iron) in children with leg pain versus a control group. Leg pain sub-groups-growing pains (GP), restless legs (RLS), both (mixed)-are defined for the first time. A case controlled study design, in a primary care setting, Mumbai, India. A total of 77 children with leg pains (n = 64) and controls (n = 13), aged 3-12 years, identified by paediatricians, completed data collection. Blood assays for iron and vitamin D, pain, Beighton score, foot arch, foot strength and anthropometrical data were collected. All outcome measures were validated, with standardised protocols. Leg pain (all groups) was predicted by increased joint mobility and increased ankle dorsiflexion strength (β = 0.56, P < 0.05). GP sub-group was predicted by increased ankle dorsiflexion strength (β = - 0.06, P < 0.05). Mixed (GP/RLS) and RLS sub-groups were predicted by increased ankle dorsiflexion strength (β = 0.66, P < 0.05) and pain questionnaire (β = 0.11, P < 0.05). Hypovitaminosis D was detected in 87% of the sample, and anaemia in 13%. Increased strength of ankle dorsiflexors and joint flexibility were each found predictive for leg pain. Increased body weight, waist girth, and BMI were all associated with leg pain.