Objective
Rising from a sitting position is very common, yet essential activity in daily life. The activity to perform the sit-to-stand (STS) transfer is a prerequisite for upright mobility. The children with spastic hemiplegic cerebral palsy have postural asymmetry and unequal development of movement patterns of the two sides, which may influence on STS pattern in these children. This study is aimed to evaluate STS pattern in cerebral palsied children with spastic hemiplegia, in comparison with the normal children.

Method
Twelve young children with spastic hemiplegic cerebral palsy and 21 normal developed children were recruited as subjects. A motion analysis system using a Motion analyzer (Vicon 370 M.A. with 6 infrared cameras) was used to examine the STS task. The changes in joint angle, moment, and power of each joints in lower limbs, total duration of STS transfer and each transitional points were assessed.

Results
Total duration of STS and the first phase duration of forward trunk lean (from T₀ to T₁) was significantly prolonged in hemiplegic children (2.09 sec; 0.70 sec) in comparison with those of normal control children (1.13 sec; 0.32 sec). Maximal hip extension power and maximal knee extension moment and power were significantly decreased in plegic side (0.53 W/kg; 0.14 Nm/kg; 0.18 W/kg) than in sound side (0.79 W/kg; 0.33 Nm/kg; 0.48 W/kg) of hemiplegic children and normal control children (1.28 W/kg; 0.39 Nm/kg; 0.58 W/kg). Maximal ankle dorsiflexion was significantly increased in the sound side (27.8^o) of hemiplegic children than in plegic side (22.5^o) and normal control children (21.9^o).

Conclusion
Characteristics through the kinematic and kinetic analysis of STS transfer was identified in spastic hemiplgic cerebral palsied children. Slowness of speed, decreased power generation of knee and hip of plegic side and asymmetric movement of joint angles in these patients were major characteristics which were distinct from normal control children. Slowness of speed of STS was thought to be mainly from prolongation of first phase.