Spinal Orthosis Mechanics



Spinal Orthosis Mechanics

End-point control – has top & bottom to semi-immobilize joints/areas

Total contact – whole surface touched…decreases rotation

3-point system – 2 forces on direction, 1 force opposite in middle

Counter-pressures – brace contact doesn’t allow movement in a given direction

Cervical Orthoses

Soft foam – kinesthetic reminder

Rigid plastic – mild control for soft tissue injury…no rotation control

Philadelphia – soft tissue damage up to C4 or stable Fx

2 & 4-poster – adjustable limits…endpoint control

SOMI – endpoint control…don in supine…can’t put into MRI

Minerva CTO – total contact, extra-stable Philadelphia…hot & hard to don

HALO – can do distraction…limits ALL mvmt…invasive

History of Orthotics

Back to 5th Dynasty

Scoliosis bracing early 1900s

Certifying Organizations – ABC or BOC

Perry – Biomechanical abnormalities of Post-Polio patients and the implications for orthotics management

Post-Polio Pts have normal sensation & motor control

Only need orthoses if substitutions are inadequate / cause joint overuse

Most common is drop-foot…substitution taken is excessive hip flexion ( use dorsi-assist device

Goals of LE Orthoses

( P! by ( forces around joint (try to distribute forces over as great an area as possible

Assist locomotion & stability

Maintain deformity correction

Influence muscle tone

Shoewear

Environmental protection…support…shock absorption

Good shoe needed for many orthoses…and for efficient gait

Poor shoe may ( shearing…cause deformity…lead to fall

Sole – welt, outsole, inner sole, shank

Upper – vamp, tongue, rear quarters

Heel – cushioned or beveled

Reinforcements – widen toe box, shank, counter

Lifts for leg length discrepancy of it locked KAFO on one side

Heel wedge for varus/valgus

Rocker bottom for improved rockers

Beveled/cushioned heel for ( lever arms for ( force on LR

Heel flares for rolling medial or lateral

Metatarsal pad for pressure shifting

Metatarsal bar for ( pressure during toe-off

Metal vs. Plastic Considerations

Edema / swelling (use metal) Heat resistance & environmental temp.

Sensation / skin integrity Cosmesis (usually prefer plastic)

Weight limit 180lbs for plastic Shoe choice

Weight of brace for metal

KAFOs

3-point system controls excess knee flexion in stance

Use anterior offset joint for genu recurvatum (usually Post-Polio)

Useful in unlocked position for ( proprioception or severe medial-lateral instability

Bilaterally…( energy cost…( velocity (more than wheelchair)…( shoulder forces

Drop locks vs. bail locks

AFOs

Ground reaction ( knee extension moment during stance

For weakness/spasticity…( stability…indirectly stabilize knee

Rigid for…severe PF spasticity/tone…mild gastroc tightness…( DF/KF moment…( tibial

progression…use cushioned/beveled heel

Articulating to control DF/PF

Dorsi Stop / Dorsi Assist – weak PFs, excess DF stance, excess PF swing, ( tibial control

Leaf spring is dorsi assist – correct foot drop, no tibial control, mild calf weak/tight

Polyarticulating for more precise adjustment

Beekman – Effects of a DFstopped AFO on walking in incomplete SCI patients

DFstop AFOs don’t disrupt calf muscle recovery postSCI

DFstop AFOs ( gait speed & step length

DF stop AFOs better knee position ( ( stance limb stability

No change in PF or Quad function…but ( pretibial function

Lehmann – Gait abnormalities in hemiplegia: correction by AFO

Main AFO benefits: ( speed & normalize heel strike via PFstop

Poorly adjusted/locked AFO ( ( difficulty of gait…(KF moment ( knee instability

Rancho ROADMAP

KAFOs & RGOs ( ................
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