L1: Orthotics--INTRO Flashcards
Orthotics
Purpose:
Transfer GRFs and other forces generated by the patient to a balanced parallel force system to control joint motion
-
Force (vectors)→ 3 characteristics:
- Magnitude
- Direction
- Point of Application (POA)
Orthotics use what type of lever system?
First class lever system
- Bw 2 ends of of a segment where the force is occurring
Orthotics
Three Point Loading System
- Prox and Dist force applied in SAME DIRECTION
- COUNTERBALANCED→ by third force in the OPPOSITE direction somewhere in bw them
*NOTE: If motion control is desired in multiple planes→ may need MORE points. AKA more control needed==more restrictive AFO
More control needed===
More restrictive AFO
An orthotic is designed for what?
- Designed to apply force of a particular magnitude at a specific point on a body segment in the presence OR absence of WB
- NOT JUST FOR STANCE→ keeps ankle neutral in Sw phase
Orthotics problems if too much force or force over a long pd of time ===
Tissue deformation and skin breakdown
Pressure==
F/A
Orthotics→ Three Point Force System
- The magnitude of the central force (anterior directed force) DECREASES as the posterior directed force moves FURTHER UP the femur and DOWN the tibia
- Orthotics that cover the majority of a body segment Prox and Dist to a segment provide greater leverage and a more comfy fit
- The problem is→ LONGER prosth== LESS cosmetic in appearance and more diff. to don/doff
Forces translated to the body thru an orthotic are designed to be distributed over ___________
As much surface area as possible
*relief areas, padding, flexible load absorb materials further alleviate forces==comfort
Orthotics:
As a first class lever system, the magnitude of opposing forces must sum to…
ZERO !!!!
Force and Counterforce Systems
Sagittal Plane knee flexion vs Frontal Plane knee valgus
see pics
No orthotic is perfect!
Cannot mimic exact biomech. anatomical joint
Bc diff. bw anatomical joints (triplanar or polycentric axes) and orthotics (single axis)→ there will be a torque or moment translated to joint at some point in ROM
Placement of straps, bands, or pads
Purpose:
MINIMIZE forces
INC comfort
Desired Effect of orthotic
Stability vs. Mobility
Orthotics: Footwear
3 things suitable footwear does
- Minimizes stress on all portions of feet
- Provides support
- Acts as shock absorber for GRFs
Orthotics-Footwear
Sole
- Durable BUT not so rigid to interfere w/ toe rocker (MTP hyperEXT) during TSt
Orthotics-Footwear
Upper
2 Styles and preferable style
- Blucher and Bal Oxford styles
- Blucher closure==preferable w/ orthosis
Orthotics-Footwear
Heel (¾ inch is standard)
¾ inch is standard
- Absorbs shock and disperses GRFs @ IC
- Limtd ankle motion (anatomical) benefit from SOFTER compressible heel (on shoe)
Orthotics-Footwear
Counter (top of heel/”back of shoe”)
- Reinforces heel
- Prevents excessive calcaneal/rearfoot motion
Orthotics-Footwear
Toe Box
- Enough height to accommodate for toe deforms (i.e. hammer toes)
Orthotics-Footwear
Last
-
Determines shape of shoe
- Straight, medial, outflared
- MOST shoes have medial last
- toe box directed inward from heel
Orthotics-Footwear
see pics
Footwear facts to keep in mind
Wt Gain
Wt gain as little as 9lbs over a 5yr period INCs foot size by one full size**
- pregnancy
- obesity
- distal edema
Orthotics-Footwear
Women love shoes!
Important details
- Rarely assess width→ Results in:
- calluses
- corns
- bunions
- hammertoes
- ingrown toenails
- MOST wear shoes that are too small
