Ambulatory Brace for Ambulatory Brace for Child with SpinabifidaChild with Spinabifida

Grace Gaylord

Ben Schnitz

Advised by: Kevin Robinson, MS, PT, OCS

Characteristics of SpinabifidaCharacteristics 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

Three Levels of SpinabifidaThree 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

Incidence of SpinabifidaIncidence 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%)

Implications of SpinabifidaImplications 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

Current Brace TechnologyCurrent 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

Problems with Current BraceProblems 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

Group ObjectiveGroup 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

Work Completed up to First PresentationWork 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

Work Completed Since First PresentationWork 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

Current WorkCurrent 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

Future WorkFuture 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!!!

Calculations of Mechanical AdvantageCalculations 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

Why Use a Sliding Mechanism?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.

Width Length Angle Sine Cosine15 10 33.7 0.55 0.8315 20 53.1 0.8 0.615 30 63.48 0.89 0.4515 40 69.49 0.94 0.3515 50 73.3 0.96 0.2915 60 75.9 0.97 0.2415 70 77.9 0.98 0.21