Knee-Ankle-Foot Orthoses for Ambulation

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An upper motor neuron starts in the motor cortex of the brain and terminates within the medulla (another part of the brain) or within the spinal cord. So, an UMN disorder would include injury, disease or disturbance within this pathway from or within the brain and to the spinal cord (Photo 6). Some examples of diagnoses of UMN disorders are: Spinal Cord Injury, Multiple Sclerosis, Stroke and Primary Muscle Disease. UMN disorders involve various degrees of spasticity and synergy patterns. The synergistic pattern will be an extensor or flexor synergy pattern.

Upper Motor Neuron Pathway
Photo 6: Upper Motor Neuron Pathway
Photo courtesy of: Perry J. Normal and Pathological Gait. In: Goldberg B, Hsu J, ed. Atlas of Orthoses and Assistive Devices, 3rd edition, St. Louis: Mosby; 1997, 77.

The most common UMN disorder for which a KAFO is prescribed is a spinal cord injury (SCI). To communicate accurately about SCI patients, it is necessary to understand the classification of SCI levels.15 In describing SCI patients, a functional level is used rather than an anatomical level. For example, a C6 quadriplegic denotes a patient with a C6 motor functional level (wrist extensor functionally present) rather than an injury at the C6 vertebral level. Indications for various levels of lower limb bracing and the expected ambulatory outcome after SCI have been well defined according to the level of injury and the lower extremity motor score.3

Each level of spinal cord injury has specific motor and sensory physical findings.

  • For a complete injury in the low thoracic or higher lumbar regions, the use of KAFOs is commonly bilateral and pelvic extensions across the hip (HKAFO) may be required.
  • For an incomplete injury, the necessary orthoses must be adjustable to support weak segments yet allow for change in muscle strength grades.

Hybrid orthoses using FES and other hip flexor assistance devices continue to be extensively studied for the SCI population.4

Sensory Loss

The sensory loss that occurs in SCI often results in a loss of protective sensation.15 For example, the skin capillary pressure is much less than the pressure over the ischial tuberosities with sitting. Therefore, SCI patients must consciously relieve pressure over bony prominences to avoid pressure sores.

Multiple Sclerosis and Stroke

KAFO use and acceptance for multiple sclerosis, stroke and brain injury is less successful and has essentially been discontinued in hemiplegic patients.4,16,17 Limb weakness in these conditions is usually global, including hip flexors, the trunk, and there is often associated ataxia, motor in-coordination and arm weakness. All of which can create challenges for the patient when donning and doffing an orthosis and using gait aids. If an orthosis is used, typically an ankle-foot-orthosis (AFO) is the most complex system used for this population.

Primary Muscle Disease

Adults with primary muscle disease, including forms of late-onset muscular dystrophy (MD) or myopathy, may rarely require KAFOs. Typically the weakness is proximal, involving the hip girdle and the additional weight of the orthosis is not well tolerated. Higher levels of bracing such as KAFOs and HKAFOs are seen primarily in the pediatric age group with muscle diseases and by the time adulthood is reached, the patient is usually nonambulatory.18

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