Orthoses For Spinal Deformity Flashcards
What is the primary goal of using orthoses for spinal deformity?
Prevent progression of deformity (via stabilizing the spine over the pelvis)
What are 4 principles of stabilization for spinal deformity?
- Endpoint control
- Transverse load
- Curve correction
- Combined effect
The design of a spinal orthosis for deformity depends on what factors (2)?
- Level of deformity (curve)
2. Magnitude of deformity
What are the two main goals for bracing AIS?
- Prevent progression of deformity
2. Delay or prevent need for surgery (fusion)
What are the criteria for bracing AIS?
25-40˚ curve with at least 2 years of remaining growth
What effect does end-point control have on a spine?
End point control increases the critical load of a curve
Based on Euler’s theoretical model, a column with one end fixed is __ times as stiff as normal? Both ends fixed?
A column is 8x as stiff with one end fixed and 16x as stiff with both ends fixed
Transverse loading and correction of a curve increases the ___ of the spine.
Critical load capacity / Spinal load carry capacity
A transverse load is directed where?
At the apex of the curve
Does transverse loading or curve correction have a greater effect on increasing the critical load of the spine?
Curve correction has a greater effect, more important
The effect of transverse loading and curve correction on critical load capacity is ___ for larger curves compared to smaller curves.
Reduced
A 30˚ curve has what percent of normal critical load capacity?
50% of normal
TLSOs for spinal deformity are typically worn how many hours per day?
18-23 hours per day
TLSOs for spinal deformity can treat curves with apices as high as:
T7/T8*
What negative effect did the mandibular/occipital extension on the original Milwaukee brace have?
Orthodontic deformities / pain
What was the theoretical effect of a mandibular/occipital extension on the original Milwaukee brace?
Longitudinal distraction
The mandibular/occipital extension of the Milwaukee brace was replaced with what component?
Neck ring (does not create distraction)
What is the function of the neck ring on a Milwaukee brace?
Reduce sway of the vertebral column (keep upper spine centered over sacrum)
What is the proximal constraint on a Milwaukee brace?
Neck ring
Describe placement of the thoracic pad.
- Over apical rib (rib that articulates with the apical vertebrae) and next inferior rib
- Spans from medial aspect of paraspinal musculature to midcoronal line (posterolateral quadrant)
What effect does thickening the thoracic pad posteriorly or contouring the bars of a Milwaukee brace inward have?
Increases anterior de-rotational force
On a Milwaukee brace, what is the purpose of the anterior outrigger for the thoracic pad?
Keeps the strap away from the body anterior to the midcoronal line so as to keep force vector of the thoracic pad directed antero-medially. (Avoid counterforces)
Describe adjustments to the Milwaukee brace for hypokyphosis.
Thoracic pad should be placed directly laterally (no anterior directed force).
Anterior outrigger can be shortened or eliminated.
Neck ring centered more anteriorly to induce kyphosis
Describe adjustments to the Milwaukee brace for hyperkyphosis.
Pad placed over the apex of the kyphotic hump either floating (attached to a strap) or static (attached to the posterior uprights which can be contoured to increase force)
Describe placement of the lumbar pad.
- Inferior to the costal ribs and superior to the iliac crest
- Directly over the apex of the curve in the posterolateral quadrant (midcoronal line to medial paraspinal muscles)
What shapes are the thoracic and lumbar pads?
Thoracic - arc shaped (ribs)
Lumbar - triangular (contoured to waist)
The pelvis girdle on a Milwaukee brace serves what functions?
- Provide a foundation for the orthosis
- Increase intraabdominal pressure
- Provide a distracting force
What identifies a primary curve?
Curve with the greatest mechanical stiffness
In what order are primary and secondary curves loaded and shifted?
Primary curve loaded and shifted first, followed by loading of the secondary curve (with minimal shifting)
Double primary - shift and load curves equally
What is the primary mechanism to reduce spinal curve magnitude?
Pad force
What direction does the load vector point for thoracic and lumbar pads? What about with hypokyphosis?
Anteromedial (hypokyphosis - medial only)
Where is the general location for thoracic and lumbar pads?
Posterolateral
What determines the magnitude of force for thoracic and lumbar pads?
Maximum tolerable (evaluated clinically by redness and comfort) Force < Skin Tolerance to avoid skin breakdown Increase force if redness dissipates in 15 minutes
Why does the orthosis need to be tightened / pads increased periodically?
Viscoelastic relaxation of soft tissues as curve reduces
