Developing a technique to measure intra-limb coordination in gait: applicable to children with cerebral palsy

Lower limb intra-limb coordination was investigated using sagittal plane kinematic data extracted from gait data recorded using a Vicon system (Vicon Motion Systems Ltd., Oxford, UK) of 20 normal (N) and 20 children with cerebral palsy (CP). Walking speed, maximum and minimum flexion and range of motion (ROM) were calculated. The repeatability of the data was checked by calculating the coefficient of multiple correlation. Data were also processed to determine angular velocity of hip and knee joints. A logical spreadsheet was devised to determine when both joints moved in the same direction (in-phase), in different directions (antiphase, AP) or if either joint was immobile (JS). In-phase joint motion was further subdivided into in-phase flexion (IPF) and in-phase extension (IPE), which comprises in-phase during stance phase (IPEst) and in-phase during swing phase (IPEsw). Data were processed using two threshold values for angular velocity below which the joint was considered to be immobile. The threshold values used were 0.05 degrees /% of gait cycle and 0.025 degrees /% of gait cycle. Children with cerebral palsy had reduced ROM and walked more slowly than normal children. There are significant differences between N and cerebral palsy coordination phases with marginally greater significance at the 0.05 degrees /% threshold for most component parameters; the exception being in-phase flexion. It is therefore suggested that this threshold value (0.05 degrees /%) is used for future work.