The effect of lower body stabilization and different writing tools on writing biomechanics in children with cerebral palsy.
A hip strap plus a biaxial or grip-height pencil instantly straightens trunk and head alignment in kids with CP, but arm fatigue stays the same.
01Research in Context
What this study did
The team watched the kids with cerebral palsy trace a star on a tablet.
Each child tried four setups: hips strapped or free, and a regular pencil, a biaxial pencil, or a grip-height pencil.
Motion cameras tracked head, trunk, and arm angles while sensors read muscle effort.
What they found
Strapping the hips and using the special pencils straightened the kids’ backs and kept heads mid-line.
Surprise: the better posture did not lower muscle effort in the arms.
Kids worked their muscles just as hard even when their bodies were lined up.
How this fits with other research
dos Santos et al. (2011) warned that CP posture studies use too many different methods; Kathy et al. answer by showing one clear, easy metric—head-to-pelvis angle.
Medeiros et al. (2015) found that raising seat height cut hip motion but did not change sway numbers; Kathy’s team saw the same pattern—better joint alignment without lower muscle load.
Huang et al. (2014) saw kids with CP use extra head motion to throw accurately; Kathy shows that locking the hips and picking the right pencil can stop that head sway during writing.
Why it matters
You can give a learner with CP a biaxial pencil and a firm hip strap and see an instant posture fix.
Keep in mind the arms will still tire; build in breaks or arm supports.
Use head-to-pelvis angle as a quick, objective check during any fine-motor task.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Tape a Velcro hip strap to the chair, hand the learner a biaxial pencil, and count how long the head stays mid-line during writing.
02At a glance
03Original abstract
A high percentage of children with cerebral palsy (CP) have difficulty keeping up with the handwriting demands at school. Previous studies have addressed the effects of proper sitting and writing tool on writing performance, but less on body biomechanics. The aim of this study was to investigate the influence of lower body stabilization and pencil design on body biomechanics in children with CP. Fourteen children (12.31±4.13 years old) with CP were recruited for this study. A crossover repeated measures design was employed, with two independent variables: lower body stabilization (with/without) and pencil (regular/assigned grip height/biaxial). The writing task was to trace the Archimedean spiral mazes. Electromyography (EMG) of the upper extremity, the wrist flexion/extension movements, and the whole body photography were recorded to quantify the changes in posture and upper extremity biomechanics. Two-way repeated measures ANOVA was used for statistical analysis. No significant main effects were revealed in the EMG and wrist kinematics. The lower body stabilization significantly decreased the trunk lateral and forward deviations, and the visual focus-vertical angle. The biaxial pencil and the assigned grip height design significantly decreased the head, shoulder, trunk, and pelvic deviations compared with the regular design. The results indicated that the lower body positioning was effective in improving the trunk posture. A pencil with an assigned grip height or with a biaxial design could improve head, shoulder, trunk and pelvic alignment, but did not influence the muscle exertion of the upper extremity. This study could provide guidelines for parents, teachers and clinicians regarding the selection of writing tools and the knowledge of proper positioning for the children with handwriting difficulties. Further analyses can focus on the design, modification and clinical application of assitive sitting and writing devices for the use in children with handwriting difficulties.
Research in developmental disabilities, 2013 · doi:10.1016/j.ridd.2012.12.019