The gait is less stable in children with cerebral palsy in normal and dual-task gait compared to typically developed peers

To address the need for a standardized system to classify the gross motor function of children with cerebral palsy, the authors developed a five-level classification system analogous to the staging and grading systems used in medicine. Nominal group process and Delphi survey consensus methods were used to examine content validity and revise the classification system until consensus among 48 experts (physical therapists, occupational therapists, and developmental pediatricians with expertise in cerebral palsy) was achieved. Interrater reliability (kappa) was 0.55 for children less than 2 years of age and 0.75 for children 2 to 12 years of age. The classification system has application for clinical practice, research, teaching, and administration.

The well-known condition for standing stability in static situations is that the vertical projection of the centre of mass (CoM) should be within the base of support (BoS). On the basis of a simple inverted pendulum model, an extension of this rule is proposed for dynamical situations: the position of (the vertical projection of) the CoM plus its velocity times a factor (square root l/g) should be within the BoS, l being leg length and g the acceleration of gravity. It is proposed to name this vector quantity 'extrapolated centre of mass position' (XcoM). The definition suggests as a measure of stability the 'margin of stability' b, the minimum distance from XcoM to the boundaries of the BoS. An alternative measure is the temporal stability margin tau, the time in which the boundary of the BoS would be reached without intervention. Some experimental data of subjects standing on one or two feet, flatfoot and tiptoe, are presented to give an idea of the usual ranges of these margins of stability. Example data on walking are also presented.

This is a review of the proprioceptive senses generated as a result of our own actions. They include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents. Afferent signals generated during a movement are processed to code for endpoint position of a limb. The afferent input is referred to a central body map to determine the location of the limbs in space. Experimental phantom limbs, produced by blocking peripheral nerves, have shown that motor areas in the brain are able to generate conscious sensations of limb displacement and movement in the absence of any sensory input. In the normal limb tendon organs and possibly also muscle spindles contribute to the senses of force and heaviness. Exercise can disturb proprioception, and this has implications for musculoskeletal injuries. Proprioceptive senses, particularly of limb position and movement, deteriorate with age and are associated with an increased risk of falls in the elderly. The more recent information available on proprioception has given a better understanding of the mechanisms underlying these senses as well as providing new insight into a range of clinical conditions.