Three-dimensional in vivo quantification of knee kinematics in cerebral palsy.

Cerebral palsy is the most common disabling condition in childhood, involving a diverse group of movement and posture disorders of varying etiologies. Yet, much is unknown about how cerebral palsy affects individual joints because currently applied techniques cannot quantify the three-dimensional kinematic parameters at the joint level. We quantified the effects of cerebral palsy at the knee using fast phase contrast MRI, with the ultimate intent of improving the assessment of joint impairments associated with cerebral palsy, improving clinical outcomes, and reducing the impact of cerebral palsy on function. We addressed three questions: (1) Can patients with cerebral palsy perform the required repetitive extension task? (2) Which of the 12 degrees of freedom defining complete knee kinematics are abnormal in individual patients with cerebral palsy and is the patellar tendon moment arm abnormal in these patients? (3) Are the individual kinematic differences consistent with clinical observations? All patients were able to perform the required task. We found kinematic differences for each patient with cerebral palsy consistent with clinical findings, in comparison to an able-bodied population. Fast phase contrast MRI may allow differentiation of patellofemoral and tibiofemoral function in various functional subtypes of cerebral palsy, providing insights into its management.