Muscular control
A longitudinal study (McDonald et al, 2007) evaluated the effectiveness of adaptive seating systems using sacral pads and kneeblocks. Statistically significant differences before and after kneeblock removal were found for force at the kneeblock, but no difference was found in pressure at the sacral pad. No statistically significant correlations between force and pressure or posture were found. This study suggests that seating systems using a sacral pad and kneeblock may not improve overall posture but may improve hip position in children with CP.
A pre-post study (Martinsson et al, 2011) studied the effect of 1 year of daily, straddled weight-bearing on hip migration percentage and muscle length in non-ambulatory children with cerebral palsy. Participants using straddled weight-bearing after surgery had the largest decrease in migration percentage (n=3, 20 controls;P=.026). Children using straddled weight-bearing at least 1 hour per day for prevention also improved (n=8, 63 controls;P=.029).
Conclusion: There is limited evidence (level 2b) from two quasi-experimental studies supporting the use of seating systems to improve/maintain hip position in children with cerebral palsy.
Pressure distribution
A systematic review (Michael et al, 2007) was conducted to inform clinical practice on seating provision and use, and identify what further research is required in order to establish evidence-based guidelines for provision. Overall there is a lack of quality evidence to support and guide the use of the tilted position.
A quasi-experimental study (Braccialli et al, 2011) determined the influence of flexibility of the chair seat surface on the pressure peak and on the contact area during the execution of a task of handling an object on the seated position by individuals with spastic cerebral palsy. A significant difference between the pressure peaks between the canvas seat and a wooden chair was found (p=0.02). A flexible canvas seat increased the contact area and decreased the pressure peak and the medio-lateral displacement of centre pressure on the seated posture.
Conclusion: Limited (level 2b) evidence from one quasi-experimental study supports the use of adaptive seating to reduce pressure distribution while seated in children with cerebral palsy.
Sitting posture
A systematic review (Chung et al, 2008) reviewed the research on adaptive seating effects on sitting posture in children with CP and examined whether changes in postural control influenced functioning. Conflicting findings were reported for saddle seats and optimal seat/back angle for improving sitting posture/postural control. Significant improvements were reported with seat inserts, external supports, and modular seating systems. Evidence supporting effects of postural control on functional abilities was limited.
A literature review (McNamara et al, 2007) evaluated the current research looking at the impact of seat inclinations upon postural control, muscle activity and upper extremity function in children with cerebral palsy. Improved postural control and a reduction in pathological movements were achieved in anterior tilt; reduced postural sway was evident for children with spastic cerebral palsy sitting on anterior incline, and increased sway for those with hypotonia; extensor thrust was evoked when in posterior incline.
A quasi-experimental study (Hadders-Algra et al, 2007) determined the effect of seat surface tilting on postural control and quality of reaching in children with cerebral palsy. In the children with bilateral spastic CP, both forward and backward tilting of the seat surface was associated with more postural instability.
A consensus statement determined that postural management is helpful for children with bilateral CP for communication, cognitive/ functional skills, participation and may reduce deformity. Postural intervention can be guided by the GMFCS. Children in GMFCS groups IV-V should start 24-hour postural management programmes in lying after birth, in sitting from 6 months, and in standing from 12 months. GMFCS level III should emphasize postural activity from an early age. Close surveillance should be maintained for the development of postural or positional deformity to soft tissues and bony structures. All children who cannot walk more than 10 steps by 30 months should have a hip X-ray to measure migration (repeated every 6-12 months until the age of 7) and spine X-rays for GMFCS V and IV unable to stand by the age of 5 years (at 5 and 10). Intervention to prevent deformity is provided as an integrated approach between postural management equipment, activity, and surgery. Decisions should be based on a child’s clinical and functional activities, pain levels, sleep assessment, hip migration percentage, long-term prognosis, and social implications. Postural care pathways and training are needed to enable the active understanding and involvement of all those involved with the child. More evidence for the effectiveness of intervention is needed.
Conclusion: There is limited evidence (level 2b) from a literature review and a systematic review as well as a consensus statement (level 3 evidence) supporting the positive effects of seating systems on postural control in children with cerebral palsy.
