Influence of muscle morphology on muscle strength and gait in children with haemophilia

Improvements in medical treatment mean that although joint haemorrhages still occur and radiological signs of joint damage continue to be found in young boys with haemophilia, they present with no apparent clinical signs of joint damage. Evaluating muscle strength with an isokinetic device, muscle morphology with ultrasound imaging and gait patterns with 3-D motion capture, the primary aim of this study was to investigate whether muscle strength, morphology and gait characteristics of children with haemophilia differed from those of typically developing children. No joint or muscle impairment was detected with the Colorado Physical Examination in twenty-six boys with haemophilia, aged 6-12 years and a history of ankle joint haemarthrosis. But compared to a group of twenty-six age and size-matched typically developing boys, those with haemophilia showed deficits in isokinetic muscle strength of the knee extensors, ankle dorsi and plantarflexors (p<0.05), together with reduced size of vastus lateralis and lateral gastrocnemius muscles (p<0.05). Adaptations in walking were also found (p<0.05); greater knee flexion and ankle dorsiflexion angles, vertical ground reaction forces, knee flexion moments, ankle external rotation moments and EMG activity of lateral gastrocnemius. Regression analysis identified key relationships linking reduced lower limb muscle strength, altered muscle morphology and biomechamcal adaptations of walking patterns in boys with haemophilia (p