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Uploaded bySmita Nayak
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Tone reducing orthosis

The document discusses the concept of muscle tone and its implications in rehabilitation, particularly in patients with neurological impairments. It details the evolution of tone-reducing techniques, including orthotic designs and casting methods intended to improve patient function by addressing excessive muscle tone. Additionally, it covers the relationship between muscle tone and reflexes, along with various clinical manifestations and management strategies for conditions like hypertonia and hypotonia.

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BY:- MISS SMITA NAYAK MPO (2011 BATCH)
 Tone is a normal characteristic of muscle physiology and defined as “ normal degree of vigour and tension: in muscle, the resistance to passive elongation or stretch”  Tone and reflex activity assist the infant to balance and maintain posture during the developmental process of standing and walking. As the higher learning of movement develops the primitive reflexes diminish.  Overactivity of tone and reflexes in the neurologically impaired patient is a greater challenge for the Rehab professionals.
 Tone reducing concepts have evolved from neuro developmental techniques, utilised in inhibitive cast to reduce excessive amounts of tone or spasticity.  The inhibitive casting techniques of the past involved the custom manufacture of a plaster or wooden foot plate that applied the pressures to specific regions of the foot. The modified foot plates were then wrapped into a below knee walking cast. In the development of this technique over the last 10 years commercial fabrication facilities have produced pre fabricated foot plates that incorporate these features to increase efficiency of impression casting.
 The concept began in the late 1960s with the introduction of thermoplastic molded orthoses and the design possibilities afforded by total contact. As neuro physiological approaches were developed to include tone- reducing casts and temporary splints from low- temperature plastics, the implication to orthotic practice became clear  The biomechanical and total contact features of plastic orthoses had been enhanced by the emergence of neurophysiological handling techniques. The result was a markedly improved function for the patient with a central nervous system disorder. The efficacy of tone reducing theories have been debated and varying opinions are held in regard to their demonstrable effect.
 Tone literally means the activation of muscle.  Muscle tone is what enables us to keep our bodies in a certain position or posture.  To complete a movement smoothly, the tone in all muscle groups involved must be balanced.  Hypertonia is seen in upper motor neuron diseases like lesions in pyramidal tract and extrapyramidal tract. Hypertonia can present clinically as either spasticity or rigidity.  Hypotonia is seen in lower motor neuron disease like poliomyelitis. Hypotonia can present clinically as muscle flaccidity, where the limbs appear floppy, stretch reflex responses are decreased, and the limb’s resistance to passive movement is also decreased
 Velocity dependent increase in muscle tone with exagerated tendon jerks resulting in hyper-excitability of the stretch reflex in association with other features of the Upper Motor Neurone Syndrome or  A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex…”  INCIDENCE  SCI  Closed head injury  Stroke  Cerebral palsy
Unknown 1) Denervation hypersensitivity of Alpha Motor Neuron 2) Collateral sprouting resulting in further loss of inhibitory input. 3) Hyper-excitable Gamma Motor neurons will increase the sensitivity of the neuromuscular spindle. 4) Interneuron activity and excitability. Net result is an imbalance of excitatory and inhibitory impulses resulting in a disinhibition of the alpha motor neuron.
Modified Ashworth Scale: 0 = no increase in muscle tone 1 = slight increase in muscle tone (catch or min resistance at end range) 1 + = slight increase in muscle resistance throughout the range. 2 = moderate increase in muscle tone throughout ROM, PROM is easy 3 = marked increase in muscle tone throughout ROM, PROM is difficult 4 = marked increase in muscle tone, affected part is rigid
Consequences  Increased Tone  Decreased Range of Motion  Involuntary Movements  Increased Autonomic Reflexes  Exaggerated Reflexes  Muscle Weakness  Muscle Fatigue  Muscle Control  Balance Problems  Increased Caloric Needs  Abnormal Bone Stress  Muscle Tone  Tendon Jerks  Repetitive Stretch Reflexes - Clonus  Extensor St. Reflexes  Released Flexor Reflexes - Babinski, Mass synergy pattern Positive Symptoms
 Improvements in position  Mobility  Pain  Contracture prevention  Ease of care are possible
 Inhibition of abnormal reflexes as per NDT technique.  pressure over muscle insertions,  Prolonged stretch  orthokinetics
 A design configuration intended to utilize both biomechanical principles to limit calcano- varus and neuro physiological principles (of facilitation and inhibition) to obtain dynamic ankle dorsiflexion and plantar flexion.  A neurophysiological force to inhibit the toe grasp reflex (toe flexors and gastrocnemius- soleus) by unweighting of the metatarsal heads through use of a metatarsal arch
• Prolonged stretch of the ankle plantar flexors and long toe flexors • Weight bearing in proper alignment to influence proprioceptors through joint compression. • Altered muscle length resulting in change in resistance to passive stretch. • Inhibition of reflexes induced by tactile stimulation
 When the central nervous system-which is responsible for normal voluntary control-is damaged, these primitive reflexes will again dominate motor activity and contribute to patterns of spasticity Reflexes of the foot that influence AFO designs  Planter reflexes  Positive supporting action  The inversion  Eversion reflexes
 The toe grasp (plantar grasp) reflex is triggered by pressure over the ball of the foot and results in marked increase of tone in toe flexion or ankle plantarflexion.  AFO design features that reportedly reduce stimulus pressure include spastic inhibitor bars, foam toe separators and metatarsal arch supports to un weigh metatarsal heads.
 The positive supporting reaction, also triggered by pressure over the ball of the foot, results in a total extensor pattern with a noted increase of tone in plantarflexion and inversion. AFO design features that reportedly reduce stimulus pressure include toe extensions, toe hyperextensions and pressure under metatarsal heads
2211/20/2018DHARAM
 The inversion reflex is triggered by pressure over the first metatarsal head along the medial border of the foot while, conversely, the eversion reflex is triggered by pressure over the fifth metatarsal head along the foot's lateral border
 An AFO design feature that reportedly reduces the abnormal tone of these patterns is stimulating the antagonistic reflex to balance the deformity by extending the metatarsal pad to the foot's extreme lateral margin, hereby triggering the eversion reflex . Conversely, by extending the metatarsal pad medially, the inversion reflex would be triggered .
 In 1974, Farmer reported that continuous firm pressure at the point of insertion has a tone-reducing effect . Recent orthotic literature has incorporated this AFO design by applying pressure on either side of the tendo-calcaneus and at the insertion of the gastrocnemius-soleus muscle group  Increased muscle tone in this group frequently is accompanied by excessive plantar flexion. This rationale might also be applied to control excessive knee extension tone. By incorporating a patella tendon-bearing design into a floor reaction AFO, pressure would be maintained at the insertion of the quadriceps
 Tone-reducing AFOs and inhibitory casting have been observed to decrease reflex tone by providing mechanical stabilization of the joint and altering properties of the muscle spindle through static immobilization . These goals have been achieved through a variety of designs that provide total ankle-foot contact  Plaster serial casts  Supra malleolar orthoses and  Bivalved thermoplastic AFOs .  Adjustable designs allow for a graduated change in the position of joint range at which static force is applied .
 The orthokinetic rationale focuses on the physical effects of materials placed over muscle bellies . Passive field materials (those that are cool, rigid and smooth), including thermoplastics, tend to produce an inhibitory effect. These materials do not mechanically deform or elongate underlying muscles, which would stimulate or increase muscle tone.  Active field materials (those that are warm, expansive and textured) include materials such as foam, elastic and hook/loop straps and tend to produce a facilitatory effect. During muscle contraction these materials tend to expand, providing minute pinching motions to the dermatome over the active muscle. This facilitation is referred to as extero proprioceptive stimulation, and its principles have been incorporated in AFO design .
 The foam interface on the anterior shell of the Chattanooga articulating AFO provides active field stimulation of anterior tibialis that would encourage dorsiflexion. The unpadded posterior shell of a conventional AFO provides passive field inhibition to gastronemius, reducing spasticity to plantarflexors. It is important to understand these dual orthokinetic concepts are interrelated and should be applied simultaneously. When attempting to provide passive reduced stimulus over the hypertonic muscle, always apply active increased stimulus over the antagonist muscle groups
• Calf shell extends from midcalf to shoe insert • Insert has a distal wedge under the MT heads to abduct the toes. • Strap over the dorsum of foot or snug shoe closure controls the midfoot & holds the hind foot in best attainble alignment. • This position of foot & ankle prevent from activating extensor synergy during stance.
 When ankle DF during midstance & TS the leg pulls away from the shell  Preswing when ankle PF the leg pushes against the shell. It gives a proprioception & tactile input to stimulate ankle DF & minimise toe drag.
 Cyndi Ford, The Neurophysiological Ankle-Foot Orthosis Clinical prosthetic & orthotic vol-10,no-1 page-15-23  JAMES E. Effect of Tone-Inhibiting Casts and Orthoses on Gait PHYS THER. 1982; 62:453-455.  Michael Loh Alternative Strategies in Tone-Reducing AFO Design man JPO 1993 Vol. 5, Num. 1 pp. 1-4  Bipin B Bhakta Management of spasticity in stroke British Medical Bulletin 2000, 56 (No 2) 476-485  MICHAEL R BARNES Management of spasticity Age and Ageing 1998; 27: 239-245
Tone reducing orthosis