Applications of Assistive Technology

Applications of Assistive Technology
Positioning and Mobility Objectives: List and discuss 9 reasons why properly positioning a child or adult is the necessary first step in any AT intervention. Discuss the 4 principles of successful postioning. Discuss the structural abnormalities, muscle tone problems, and postural reflexes that can effect proper positioning of children and adults with severe disabilities. List 4 factors for proper alignment when in a sitting position. Discuss the importance of properly positioning the legs and lower extremities as well as the head and upper extremities. Identify the different types of standers, floor postioning devices, and wheelchairs that can be used to position a person with a disability.

The Nine Benefits of Proper Positioning
Normalize or decrease abnormal neurological influence Maintain proper skeletal alignment Manage pressure Enhance freedom of movement through body stabilization Increase student comfort Enhance autonomic nervous system functioning Decrease fatigue Facilitate normal movement patterns Maximize function while minimizing pathology As you learned in the previous activity, proper positioning is essential for providing the person with a stable body posture that can be used to do tasks. Thus, a key component to successful use of assistive technology is the appropriate positioning of the student. Proper positioning enables the person to most effectively access the technology. In this module we will examine a number of different strategies to enhance student comfort and function through appropriate body positioning.

Normalize or decrease abnormal neurological influence Often, poor habitual patterns develop which lead to muscle contractures and skeletal deformities. Attempts at voluntary movements, because they are difficult to perform and involve different movement patters, often compromise the person's position. Neurological impairments often result in abnormal body tone and reflexes. These difficulties, in turn, affect the person's abilities to maintain their position in space. To compensate, the person must exert a good deal of effort and attention to keeping a stable position. Often, poor habitual patterns develop which lead to muscle contractures and skeletal deformities. Attempts at voluntary movements, because they are difficult to perform and involve different movement patters, often compromise the person's position. Working with physical and occupational therapists, most of the effects of abnormal tone and reflexes that result from neurlogical impairments may be inhibited through proper positioning.

2. Maintain proper skeletal alignment Persons who have poor postural control usually have problems maintaining an erect sitting posture. This can be seen when you observe the person: leaning to one side. scooting forward so that they are sitting on their tail bone (sacral sitting). hooking an arm around the handles of chairs or desks to gain support. show increased levels of fatigue. With persons who have compromised neurological functions, non-symmetrical sitting often leads to skeletal deformities. These skeletal deformities, in turn, further compromise movement and result in very effortful and inaccurate movement patterns. Often, students report discomfort (and sometimes pain) as an effect of poor positioning when they respond to the introductory activity for this topic. This is a clear example of the effects of poor skeletal alignment. Providing a stable base of external support (good positioning ) will maintain the person's body in correct alignment, counteract poor posture, and allow the person to move more freely.

3. Manage pressure Pressure sores may develop when person's with sensory deficits due to an unawareness of body position remain sitting (or laying) for long periods of time without readjusting their positions While many of us can relate to experience of discomfort from poor posture when our skeletal alignment is not optimal, pressure sores are something we generally do not experience. The closest many of us can come to this is the experience of having a sore rear from sitting too long. As uncomfortable as this seems, we can alleviate this discomfort by shifting our weight periodically. Our experiences, though, are nothing compared to pressure sores that can develop when someone spends too much time in a position. Pressure sores may develop when person's with sensory deficits due to an unawareness of body position remain sitting (or laying) for long periods of time without readjusting their positions. When pressure sores develop, they can severely affect a person's positioning, sometimes causing hospital stays. Proper positioning and appropriate cushioning can prevent pressure sores.

4. Enhance freedom of movement through body stabilization Trunk support in sitting can be provided by changing to chairs that have adequate arm support, back support, and provide a good sitting surface. If this is not sufficient, additional supports, straps or harnesses can be used to increase stability. Trunk support is the basis for controlled purposeful arm movements. When you have a firm base of support you are secure as you attempt to use our hands and arms in tasks. Without this base of support, you need to use one or more hands to brace ourself, thus restricting your ability to engage in the task. You can simulate how difficult it is to move without trunk support by sitting on the edge of your chair, raising your feet off the ground, and attempting to write on a piece of paper. Most of your effort is devoted to remaining stable, with little left to complete the task of writing.

5. Increase student comfort Proper support will increase comfort. When you are comfortable and secure in your position, your function is significantly enhanced. Proper support will increase comfort. Think of positions in which you are most productive and you will probably quickly see that these are positions in which you are comfortable. You have support that provides security and allows you to devote more directed attention to the tasks you need to perform.

6. Enhance autonomic nervous system functioning Proper support in sitting effects the following functions positively: Breathing Cardiac function Digestion Eating/Swallowing

7. Decrease fatigue The less someone must use her own muscle strength to hold herself erect, the less fatiguing sitting erect will be. Proper positioning is critical to decreasing fatigue so a student has the energy to stay on task. One of the most consistent findings good positioning is that fatigue is minimized. Many people will report that when improperly or poorly positioned, they fatigue much quicker. This makes intuitive sense and most of us can think of times in which we became more fatigued from having to be in a poor position for extended periods of time. Have you ever tried to sleep on an airplane? If so, I think you can understand why good positioning is important in decreasing fatigue associated with tasks.

8. Facilitate normal movement patterns Normal movement components enhanced are listed below: Proper weight bearing. Weight shifting. Equilibrium reactions. The ultimate result of good positioning is that the person uses normal movement patterns. Normal movement patterns are almost always more efficient, less effortful, and more effective. Thus, our goal is to encourage these tyical movements as much as possible. Anytime you need to use alternative positioning, the goal is to select a position or provide support that allows the person to use more normative movements to do the tasks they need to complete.

9. Maximize function while minimizing pathology The goal of proper positioning is to allow the student maximum environmental functioning through the use of assistive technology. Proper positioning also minimizes the abnormal postures and movements which lead to long term contractures and deformities.

Evaluation for Seating
Begin notes from Cook text p. 168

History of the Wheelchair

History of the Wheelchair
Begin notes from Cook p. 330

Notes: The developments in the wheelchair probably led to the development of the bicycle.

After WWII, wheelchair sports stared as a part of the rehab program at Stoke Mandeville Hospital in England. The purpose was to provide exercises and a recreational outlet for the many individuals who had been injured during the war

Positioning Devices Positioning Technology allows versatility in placing students in many different functional positions. The examples in this lesson depict children primarily because this is where these devices are primarily employed as a developmental tool. This does not restrict their use, however, to infants, young children, or school aged children. The principles are the same whether you are working with a child or an adult: position the person with adequate support so that they can engage in functional movement patterns and perform tasks. Positioning devices or systems are primarily broken down into standing and floor positioners

Standing Frames Standing frames place persons who are not able to maintain an upright standing position in a supported upright position. The upright supported standing position helps increase participation in activities. The standing frame comes in three main types: Prone Standers Supine Standers Upright Standers

Prone Standers In the prone standing position, the person faces forward in a standing frame which gives front support. The Frame may either be self standing or lean against a table. This position is well suited for people who have good head control and need stimulation of the extensor muscles. It is a functional position for play or work when used with a tray. Using a prone stander: The head - The prone position requires more demands on the neck as the entire head must be lifted and maintained against gravity. The hands/arms - The arms should come forward with the shoulder girdle in a neutral position so that the hands are free for functional activities. The hips/trunk - The pelvis should be in a neutral position with the weight distributed evenly over the legs . The feet - The feet should be positioned flat with the toes facing forward and the foot in alignment with the knee. The ankle should be bent at a 90 degrees with weight bearing distributed mainly through the sole of the foot.

Supine Stander In the supine standing position, the student's back rests against the standing frame. These standers are often easier to use if the stander can be cranked into position from supine lying. Supine standers tend to be better suited for students with decreased head control. Trays are often available for a work surface. Using a supine stander The head - The head rests against the back of the stander so there is less demand placed on the neck musculature. The head should be supported with lateral supports to help maintain it in a midline position. The hands/arms - The arms should be positioned in a forward position so that the elbows rest comfortably on a support such as a tray. The hips/trunk - A strap or support may be required to maintain the knees in an extended and neutral position. The feet - The feet should be positioned flat with the toes facing forward and the foot in alignment with the knee. The ankle should be bent at a 90 degrees with weight bearing distributed mainly through the heels.

Upright Stander In an upright stander, the student stands erect with all weight supported through the feet. This achieves maximum weight bearing. Good head control and trunk control is a pre-requisite for success Using the upright stander The head - The head should be positioned in a neutral, midline position. Good head control is required even though the neck does not require the strength to lift against gravity. The hands/arms - The shoulders should be positioned in a forward position and not be allowed to retract. The hips/trunk - The pelvis should be positioned in a neutral position so that the weight is distributed evenly over the legs. The knees are supported in an extended position with the weight distributed evenly over both legs. The feet - The feet should be positioned flat with the toes facing forward and the foot in alignment with the knee. The ankle should be bent at a 90 degrees.

Floor Positioners Prone floor positioners Supine floor positioners
Sidelying floor positioners There are three types of floor postitioners: Prone, Supine, and Side lying. These positioners are helpful in preventing skeletal deformities from developing and promote normal patterns of movement

Prone Floor Positioner
The prone floor positioner plays an important role in normal development. In this position, students are able to weight bear through their hands while developing good head control. This position helps to maintain elongation of muscle groups of the shoulders, trunk, and hips. Balance, weight shifting, and shoulder mobility develop as the student reaches for objects Using the prone wedge The head - The neck muscles must be strong enough to lift the head and hold it in position against gravity. In this position, the neck is more mobile so that the visual field is expanded considerably. The hands/arms - Supporting weight in a prone-on-forearms position requires good coordination between the shoulder girdle muscles and the upper back extensors. A stable and strong shoulder girdle is necessary for good hand function.

Supine Floor Positioner
This positioner helps promote symmetry, is easy to maintain, and is relatively safe. Motor function requirements in this position are minimal. Using the supine wedge The head - The head should be positioned in a neutral and midline position. The hips/trunk/legs - Because of the influence of the Tonic Neck Reflex in the supine position, a roll under the knees helps to break up the extension tone.

Side Floor Positioner Side lying promotes elongation of the weight bearing side and shortening of the non-weight bearing side. Muscle balance between the extensor and flexor groups is developed and side lying can also decrease extensor hypertonicity. When positioning students, the goal is to maintain the head in midline with the shoulders protracted and the hands toward midline within the visual field.

Factors effecting positioning
Structural Abnormalities Muscle Tone Imbalances Abnormal Postural Reflexes Alignment in Sitting Most students with severe disabilities who require positioning assistance have abnormal tone and reflexes. If a student is allowed to sit in abnormal positions over a period of time, structural abnormalities will develop. Each of these can have dramatic effects on a person's ability to complete functional tasks.

Structural Abnormalities
Scoliosis - a curvature of the spine Kyphosis - Excessive rounding of the back and shoulders. Dislocated hips - This condition requires customized cushions to assure comfort. Muscle contractures - Increase in seat to back angle of a wheelchair may accommodate hip contractures. Changing the angle of the foot plate may accommodate contractures of the ankle and knee. These structural abnormalities must be considered when assessing students for positioning devices so optimal positioning to access assistive technology is attained

Muscle Tone Problems Muscle tone is defined as the tension or resistance present in our muscles at all times Abnormal muscle tone includes too much tone (hypertonicity), too little tone (hypotonicity), or a combination of both. Muscle tone is defined as the tension or resistance present in our muscles at all times. It is the readiness of muscles to work or the degree of firmness or tension normal to a body part. Normal muscle tone enables us to "hold" our bodies in proper alignment as we move or are at rest. Muscle tone, as illustrated in figure 7, is a continuum with high tone and low tone at each end and a range of normal tone somewhere in the middle. Abnormal muscle tone includes too much tone (hypertonicity), too little tone (hypotonicity), or a combination of both. Hypotonicity, or low muscle tone, is described as an decrease in resistance to passive movement. The muscles are loose and floppy with hypermobility in the joints. Hypertonicity, or too much muscle tone, is described as an increase in resistance to passive movement.

Abnormal Postural Reflexes
Asymmetrical Tonic Neck Reflex (ATNR) This reflex interferes with keeping the head in a midline position and bringing the hands together at midline. As the student's head is turned to one side, the arm and leg on the face side extend and the arm and leg on the skull side flex. This position is sometimes called the archer's position.

Symmetrical Tonic Neck Reflex (STNR) This reflex presents with the neck extended, the arms extended and the legs flexed. As the neck flexes, the arms flex and the legs extend. This reflex interferes with reciprocal movement of the arms and legs as seen in crawling and walking. The STNR also interferes with using the hands when the head position changes.

Tonic Labyrinthine Reflex (TLR ) This reflex influences a student's muscle tone differently depending upon whether the student is supine or prone. When supine, there is an increase in overall extension in the arms and legs. When prone, there is an overall increase in flexion tone. The TLR greatly interferes with all movement and functional activities. The goal of positioning in students exhibiting a TLR is to break up the pattern of extension by bending the knees and hips.

Alignment in Sitting. Due to the amount of time students with severe disabilities spend seated, either in a wheel chair or supported seating system, it is imperative that how they sit be examined. The goal of proper seating is to provide enough support for postural stability using a minimum of external supports.

Positioning Pelvis Positioning Trunk Positioning Lateral Trunk Flexion
Forward Trunk Flexion

Pelvis Positioning When sitting, the body needs a stable, firm base of support in order to free the upper extremities for function. The position of the pelvis is critical for providing this stable base of support. The pelvis should be positioned in a neutral or slightly anterior tilt.A neutral pelvis helps to inhibit abnormal muscle tone in the legs by discouraging hip extension. It also helps to encourage contraction of the trunk muscles so the student can sit straighter. When students sit with a posterior pelvis, it indicates poor postural control, muscle weakness, abnormal muscle tone or muscle tightness. A posterior pelvis also influences leg position. When the pelvis is posteriorly tilted, there is an increase in hip extension. The legs tend to adduct (move toward the midline of the body into a scissoring posture), the knee extend and the feet plantar flex (toes point). To compensate for this influence of extension, the students will round their backs in order to bring their weight forward, they retract their shoulders and they hyperextend their necks. This poor position impairs functional use of the hands, impairs breathing function, as well as making it difficult for the students to appropriately eye gaze. Students sit with an anteriorly tilted pelvis when there is muscle weakness, very low muscle tone, severe hip flexor contracts or shortening of low back extensor muscles. In this position the students feels like they are falling forward in their chairs and they will flex their knees in order to anchor themselves in their chairs. The students retract their shoulders and hyperextend their necks in an attempt to maintain balance. The students may also exhibit an asymmetrical pelvis with one hip forward or one side elevated. This abnormality is seen when there is asymmetrical muscle tone, muscle weakness, muscle shortening or skeletal deformities. The pelvis is critical for proper positioning. Correcting pelvis alignment alters body posture and is necessary for proper spinal alignment.

Trunk Positioning One of the goals of seating intervention is to facilitate midline positioning of the head and trunk (see figure 14). Poor trunk control decreases the ability to functionally use the hands. Abnormal muscle tone, muscle shortening, muscle weakness and skeletal deformities can all affect trunk alignment.

Lateral Trunk Flexion A student may exhibit leaning to one side of the body. This may be due to abnormal muscle tone that pulls the body to one side or muscle weakness that does not provide adequate support to one side of the body. Leaning to one side can also be the result of over using one side of the body because it is more functional. A student may also lean to both sides alternately. This change in position can be due to poor postural control or disorganized tone.

Forward Trunk Flexion Students may bend forward in their seating systems due to several causes: Poor muscle strength in their backs Compensation for sitting with a posterior pelvic tilt Attempts to overcome the effects of a seating system that is improperly reclined When students bend forward in their seats, their shoulders round and they hyperextend their necks and retract their shoulders in order to lift their heads. In positioning the trunk in sitting, it is necessary that the students sit as symmetrically as possible with the head and shoulder girdle positioned as close to midline as possible. The hands cannot be freed for activities without a stable and erect trunk.

Seating Systems Seat/back angle Tilt in space Back support
Base of support Lower extremity positioning Shoulder Support Head Support Placing someone in seating system For persons with poor postural control, abnormal tone, muscle shortening or skeletal deformities specialized seating systems are needed to provide proper alignment. Their are several components to a seating system that enhance a person's alignment in sitting.

Seat/back Angle The seat and the back of a seating system helps to maintain the pelvis in the optimum position. The seat/back angle should be whatever is needed to maintain the pelvis in neutral or slightly anterior tilt, achieve proper lumbar curve and provide a base for good spinal alignment Traditional seating calls for a 90 degree seat/back angle, but some persons lack 90 degrees of hip flexion so they cannot sit appropriately in a 90 degree system. Some persons respond poorly to sitting with a seat/back angle at 90 degrees. They feel as if their upper trunk is being pushed forward and they compensate by retracting their shoulder girdles or shifting their hips forward in the chair. The angle needs to match the person's needs. For persons with increased muscle tone (hypertonicity), opening the seat/back angle to about 95 degrees may decrease hypertonicity. By decreasing muscle tone, the person is better able to use the upper extremity for functional activities. A seat/back angle of 9~98 degrees allows for better alignment of the shoulders over the hips, thus decreasing the feeling of falling forward. This angle allows the person to rest against the back support instead of having to actively maintain an upright posture against gravity. If the seat/back angle is increased, it is important to remember to use some type of head support so the head can be righted.

Tilt in space system The original intention for a tilt system was to address issues such as physiological needs; and problems with pressure, muscle tone, respiration and digestion. Tilting also enhances daily living skills of wheelchair users by making eating and communication easier and making them more comfortable Seating systems can vary in the following ways: They can be totally upright against gravity with the seat surface parallel to the floor. They can have a fixed tilt in space They can have a variable tilt that is adjustable. In a system that is in a totally erect position, the person must fight against gravity to maintain an upright position of the upper body- This is a very fatiguing position to maintain for a long period of time- After prolonged sitting, the person will slide their hips forward, incline the trunk backward, lean to one side or lean forward supporting weight on their elbows. It is unrealistic to expect a person who has postural problems to maintain this upright position the entire day. A slight tilt of 5 degrees redirects the gravitation pull on the trunk enabling the person to maintain an upright posture with less effort (see figure 16). More tilt may be required for persons who have more difficulty with postural control. The original intention for a tilt system was to address issues such as physiological needs; and problems with pressure, muscle tone, respiration and digestion. Tilting also enhances daily living skills of wheelchair users by making eating and communication easier and making them more comfortable.

Back Support Persons with poor trunk control and/or increased extensor activity require a seat back that rises to shoulder height. Additional supports to both sides of the trunk may also be needed to provide more support. A three point lateral system may be used to provide support. In this system, two supports counter each other on each side of the trunk. The third support is placed lateral to the pelvis to keep the pelvis from shifting. These trunk supports must be properly padded to prevent skin break down or injury. The trunk needs to be aligned so that the head and shoulders can be properly positioned. If the person has fair trunk support, the back rest should come to the middle of the scapula. In this position, it is important that the persons have full use of their arms without the lower ridge of the scapula catching on the edge of the seat back. Limiting scapular mobility will impair upper extremity mobility and function.

Base of Support A firm sitting base is important in evaluating a person's seating system. The sitting surface should be firm providing a good base of support. A soft or hammock type surface tends to adduct the person's legs and cause the person to sit asymmetrically. The surface should consist of a firm structure with some type of cushioning. The seat depth should be such as to provide maximum support to the thigh, with clearance of 1/2 -1" behind the knee. If the seat is too deep, the person's pelvis will move into a position tilt causing an increase in extension tone. If the seat is too shallow, the thighs will be inadequately supported. The positioning or seat belt is used to hold the pelvis in a neutral or slightly anterior tilt. The most effective position for the seat belt is low across the hips at a 45 angle. The best type of belt to use is an auto type belt or Velcro belt that goes through a eye ring that can be tightened with one hand while holding the person in position with the other hand. If a person sits asymmetrically in the chair, aligns, positioning wedges or supporting blocks may be needed as hip guides. These help to maintain the hips in a proper orientation so the legs and feet can be properly positioned.

Lower Extremity Positioning
Once the trunk and pelvis are properly positioned, the lower extremities need to be positioned. If a person exhibits a posterior tilted pelvis with an increase in extensor tone, the legs are often adducted into a scissoring position. A knee spacer or medial knee support may be necessary to maintain the legs in neutral abduction. This medial support should extend from the front of the knee to one third distance of the thigh. This support should be removable so the person can transfer out of the wheelchair. Lateral thigh or knee supports may be used when there is excessive abduction of the legs. These blocks are placed along the outside thighs or knees to help maintain neutral alignment. Superior thigh supports are used when the person pulls into excessive hip flexion. Straps are placed over the thighs to hold the legs in place. Foot rests on the seating system should be low enough to allow body weight to be evenly distributed along thighs. To maintain proper foot alignment, blocks or strapping may be required. The foot is best controlled at the heel when seeking proper foot alignment.

Shoulder Support Persons who exhibit poor trunk control often require additional upper extremity support to maintain proper align in their seating systems. When a person has forward trunk flexion that comes more from the shoulder girdle area, shoulders straps can be used to maintain alignment. H-straps provides the best symmetrical control. Rigid shoulders stabilizer help hold the shoulder girdle back allowing more upright seating and promoting back extension. These rigid stabilizer tend to be very restrict and may only be needed for functional or upright tasks and not used all the time.

Head Support In attempting to provide support for the head, it is best to use the minimal correction equipment as possible. The more support provided, the less independent use of the head the person will have Posterior support is used to prevent the head from hyperextending. This support attempts to place the head in the appropriate position for functional eye gazing. This support should be adjustable and removable so the seating system can be used with or without the support. Lateral support prevents the head from moving into horizontal rotation or lateral flexion. Care should be taken to avoid pressure over the ears. Anterior support is the most restrictive and least desirable form of head control. A headband is attached to the head rest and then placed over the forehead, pulling the head back into the head rest. Poor placement of the headband can result in the band slipping down over the persons eyes. A helmet or cap can also be placed on the persons head and then tightened to the headrest to help maintain better head alignment. Chin supports can be used to provide maximum head support by providing continuous support from the occiput to the chin- Chin supports are very limiting and can be uncomfortable.

Placing a person in the Seating System
A good seating system that provides proper alignment to a person is only effective if the person is placed properly in the system. The key to proper placement in the system is correctly positioning the pelvis. The person should be held in a flexed position and the person's bottom should be placed as far back in the seat as possible. The pelvis is then placed in a neutral position and the seatbelt is fasten and tightened. The person is then allowed to sit up straight and at this time the other adjustments to the trunk, legs, feet, shoulders and head are made to ensure proper alignment. Once the hips and pelvis are well placed and secure, good seating is easier to achieve.

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