Ambulatory Brace for Child with Spinabifida

1. Ambulatory Brace for Child with Spinabifida Grace Gaylord Ben Schnitz Advised by: Kevin Robinson, MS, PT, OCS

2. Characteristics of Spinabifida • Congenital malformation of the nervous system • Believed to be cause by folic acid deficiency in the mother • “Cleft Spine” -- Incomplete closure in the spinal column • Typically involves loss of sensation and motion below the waist

3. Three Levels of Spinabifida • Spinabifida Occulta--at least one vertebrae is open, exposing the spinal cord • Meningocele--the meninges have pushed through gaps in the spinal cord, but have left the cord intact • Myelomeningocele: A portion of the meninges and spinal cord are protruding from the back

4. Incidence of Spinabifida • Up to 40% of people have spinabifida occulta, but have no symptoms and may never know it • 1 out of 1000 births are affected by meningocele (~4%) or myelomeningocele (~96%)

5. Implications of Spinabifida • Most sufferers die shortly after birth • Survivors must endure operations throughout childhood • Learning disabilities are often associated • All sufferers must learn mobility skills with the aid of braces or wheelchairs • Problems with bone-loading deficiency

6. Current Brace Technology • Reciprocating Gait Orthoses (RGO) are currently in use • Dual cable design replaced by isocentric pivot • Most children (2-6) must also use a walker • Braces are hand-made by specialists • Design must take into account specific disease requirements

7. Problems with Current Brace • Subject has myelomeningocele, with a high level of neurological impairment • Subject is too uncoordinated to operate • Subject does not have strength to lift legs from the hip • Result: Subject prefers spending majority of time in wheelchair • Recall problems with bone-loading, circulation, organ function

8. Group Objective • The goal of this project is to design, build, and implement a brace which can be used to assist in motion for children suffering from Spinabifida. • The ultimate objective is increasing the subject’s ease of motility and time spent in the upright position

9. Work Completed up to First Presentation • Meetings with the subject and his family • Meetings with both the orthopedist and the brace specialist • Research on disease specifics and brace design • Brainstorming on possible brace design considering what we have learned

10. Work Completed Since First Presentation • Meeting with subject’s (former) physical therapist • Visits to the Machine Shop--Phil Davis • Calculations of Mechanical Advantage (see Handouts) • Purchasing of necessary materials (Cumberland Transit) • Manufacture of sliding attachment mechanism--Bryan Johnson

11. Current Work • Today is Notch Day!!! • Meeting with the subject and his parent before spring break for initial testing phase • Refining design • Addressing issue of mass production

12. Future Work • Main focus will be on refining the design, since the chance of it working the first time are about zero... • Developing new therapeutic techniques • New Deadline: April 1!!!

13. Calculations of Mechanical Advantage Weight of average five-year old = 18kg Body weight of one Leg + ½ pelvis = 25% Maximal distance of distal end of isocentric arm = 6cm Maximal length of cable moved = 1.2cm F = mg = (18kg)(.25)(9.8m/s^2) = 44.1N W = Fd = (44.1N)(.06m) = 2.65J F = W/d = (2.65J)/(.012m) = 220.5N m = F/g = (220.5N)/(9.8) = 22.5kg MA = 18/22.5 = .80

14. Why Use a Sliding Mechanism? • Changing the point of contact changes the amount of force being provided in the horizontal and vertical directions. Depending on the exact height of the walker and the strength of any particular user, the height can be adjusted to allow for more or less horizontal force from the lever.