Orthotic Fitting Principles Flashcards

When fitting a knee-ankle-foot orthosis (KAFO), the knee joint should typically be set to which position for a patient with quadriceps weakness?

Answer: Full extension (0 degrees) to provide stability during stance

Setting the knee joint at 0 degrees (full extension) provides a stable base for stance phase when quadriceps are too weak to prevent knee buckling.

A patient with drop foot requires an AFO. Which AFO design preserves the most sagittal-plane motion while still preventing foot drop?

Answer: Hinged AFO with a dorsiflexion assist spring

A hinged AFO with dorsiflexion assist spring allows plantarflexion during loading response while providing active assistance into dorsiflexion during swing phase.

In orthotic fitting, what does the term 'trim line' refer to?

Answer: The final edge cut of the thermoplastic orthosis that determines its borders and flexibility

The trim line is the edge of the thermoplastic material after cutting, and its location determines the rigidity, flexibility, and anatomical coverage of the orthosis.

Which material property is most important when selecting thermoplastic for a pediatric AFO that will undergo frequent adjustments?

Answer: Reheating and reshaping capability (thermoplasticity) with low creep

Pediatric orthotics require frequent modifications as the child grows, so materials that can be reheated and reshaped without losing structural integrity are preferred.

A patient is fitted with a cervical orthosis. Which design provides the GREATEST restriction of cervical flexion and extension?

Answer: Halo vest orthosis

The halo vest orthosis is the most rigid cervical immobilization device, providing approximately 94% restriction of flexion/extension compared to soft collars' ~26%.

During gait analysis for orthotic prescription, 'calcaneal eversion' during midstance is best corrected with which device feature?

Answer: Rearfoot varus wedge or medial heel skive

A rearfoot varus wedge or medial heel skive tilts the calcaneus toward inversion, directly correcting excessive eversion during the midstance phase of gait.

When evaluating orthotic fit, 'pistoning' in an AFO refers to what problem?

Answer: The orthosis moves up and down on the limb during gait due to improper suspension

Pistoning describes vertical movement of the AFO on the limb during walking, indicating inadequate suspension from the shoe or insufficient proximal containment.