Tilt, Recline, and Elevating Legrests for Wheelchairs
Best Practice Guidelines (BPG 13) prior to workshop at
The 4
thInternational Interdisciplinary Conference on Posture and Wheeled Mobility
SECC, Glasgow, 7 – 9 June 2010
Group members
• Lise Møldrup, OT in ETAC, Denmark
• Birgit Werge, PT The National Center for Neuromuscular Diseases, Denmark
• Elisabet Rodby Bousquet, RPT Centre for Clinical Research Västerås, Sweden
• Jan Pool, OT specialist, SIHF Habilitation Service in Hedmark, Ottestad, Norway
• Else Marie Hansen, OT and MPC in Centre for Assistive Technology, Denmark
• Helle Dreier, OT and MSI in Centre of Special Advice about Handicap and Assistive Technology, Denmark (group leader)
Index
Purpose ………..3
Target group of this paper……….3
Be aware of factors like………3
Seating assessment process………..4
Three core aspects of the seating assessment process………..4
An example of a seating assessment process model………5
Best practice regarding tilt, recline and elevating leg rests………...6
Definitions and guidelines………..7
Tilt in space………8
Range of movement………..9
What is the effect of the use of tilt? ...9
Tilt and the impact of altered gravity on the user………10
Affects of tilt on manual wheelchair propulsion ………..11
Lateral tilt.. ………..12
Tilt feature control………..12
Recline of the backrest………..13
Range of motion in backrest recline………13
Transfers in and out of the wheelchair………..13
Different backrest recline devices……….13
A recline system influence various other functions of the wheelchair and it is necessary to assess several possibilities...14
Recline in combination with tilt in space……….15
Recline and the stability of the wheelchair……….15
Elevating leg rests devices………..16
Range of movement………..16
Transfer in and out of the wheelchair……….17
Elevating leg rests as part of combined devices for specific functional purposes………17
Conclusions……….17
References………18
Purpose
The purpose of this document is to bring forward ideas and background for discussions concerning best practice at a workshop in The 4th International Interdisciplinary Conference on Posture and Wheeled Mobility 7 – 9 June 2010 in Glasgow. It is also the purpose to provide recent evidence from literature to support practitioners in the complicated process of decision-making concerning assistive technology interventions.
It is indeed a very complicated matter with no simple or ultimate answers or solutions. That is why the group members have made an effort of presenting different kinds of experiences from the different clinical practice of every group member.
This paper has no intention to pretend lightning up every single problem, but is intended to be looked upon as an introductory presentation.
The document originate from "RESNA Position on the Application of Tilt, Recline, and Elevating Legrests for Wheelchairs", approved by RESNA Board of Directors, April 23. 2008.
http://www.uchsc.edu/atp/files/Resna_Position_on_Tilt_Recline_Elevat_Legrest.pdf Target group of this paper
The target group is OTs and PTs responsible for prescription of customized wheelchairs, and able to analyse User’s needs professionally. The purpose is to choose the best wheelchair features and adaptations in every single case by making the necessary compromises and to meet the individual needs by choosing the best wheelchair-features and adaptation in every single case.
First of all the goal is to prevent different kinds of physical damage caused by the assistive devices related to a long time seated position. It could be risks like e.g. contractures, development of scoliosis, and
pressure ulcers (Kennedy P. 2003). But it is also a purpose to ensure optimal function and as good comfort as possible.
For that reason we will try to give priority to the definitions in this text and specify particular situations or wheelchair features where we consider the professionals should be aware of either usefulness or risk.
Be aware of factors like
• Body functions (the physiological and mental functions) as the anatomy, the biomechanics, the senses etc.
• Activity (the execution of a task or action of an individual) as for instance activities of daily living, mobility, communication etc.
• Participation (involvement in everyday life) as for instance education, employment, social life etc.
• Environmental Factors (the physical, social and attitudinal environment in which people live and conduct their lives) as for instance assistive technology, natural and societal
environment, systems and policies etc. (World Health Organization)
It may be of great importance to distinguish between a child and an adult wheelchair user because they may have different needs and they do have different dimensions.
It is important to distinguish between a wheelchair prescribed with the purpose of training and a wheelchair prescribed with the purpose of sitting and participating in everyday life. There may be functional contradictions using the same wheelchair for different purposes.
These reservations would of course be important to take into consideration during a systematic seating assessment process, which is recommended in clinical practice. Every adaptation is an expression of compromises, but the essential goal is to enter the right ones for the right persons.
Seating assessment process
Powered wheelchairs and manual wheelchairs with tilt in space are provided with various manual - or power operated features in order to meet the varied needs of the wheelchair user – for instance tilt, recline and elevating leg rests which is the subject of this paper.
Every single feature is in itself legitimate and necessary to some, but not necessarily a suitable solution in every single case. There may be different kinds of disadvantages using some of the features of the wheelchair like elicitation of extensor tone, creation of shear, needs of repositioning after use or perhaps tight hamstrings demanding a special attention to the transfer situation or the use of the leg rests.
(Michelle L. Lange 2003). The information collected in a study (Ding 2008) point out the need of enhancing clinical practice of wheelchair provision, resulting in better compliance with clinical instructions and appropriate use of seating functions among wheelchair users.
To be sure when to choose the features of greatest importance and suitability to the user, the therapist must carry out an analysis of the user´s needs as a core element of the seating assessment process. It is of great importance to identify the sitting ability level of the user (Pountney T.E. 2000, Pope 2007).
When this is done sufficiently it will be possible to reduce the risk of secondary complications caused by poor seated positions. A seating assessment should be the foundation to create the perfect, orthotic match between the body, the participation skills and the wheelchair (Hastings J.D. 2000, 2003 and Bolin I. 2000).
Not until then it can be considered which of the wheelchair features that would be relevant to meet the need of the specific individual.
Three core aspects of the seating assessment process
1) THE BIOMECHANICAL ASPECTS OF THE BODY RELEVANT TO THE SITTING POSITION.
The biomechanical aspects can be used as a resource correlated with the gravitational pull (Engström B. 2002). The spinal curvature and the pelvis are supposed to support the posture of the trunk and to balance the head in a stable position. With close-fitting body contact between the body and the wheelchair it is possible to maintain a safe sitting and stable aligned position from which the user can obtain a functional range of vision. It can improve the user’s spinal alignment in all three planes (Bolin I 2000, Hastings JD 2003)
The biomechanical aspects can simultaneously be used to create a sufficient redistribution platform to the body pressure. Taking torso articulation and lumbar support into
consideration here can influence the forces generated during the seated position under the buttocks (Shields RK 1988, Bush TR 2007, Geffen Pv 2008)
The therapist can use the interface potential between the whole body and all of the
wheelchair parts (meaning: the seat, the back, the feet, and the forearms) which significantly can redistribute the body weight 30% to the back of the wheelchair and 10% under the feet (Bush TR 2007). It all depends on the adaptability of the wheelchair itself which the therapist of course must make the best possible use of. It is of great importance to use the body surface potential and the natural curvatures not only for the users with no sensibility and in pressure ulcer risk but basically to every single wheelchair user. It will reduce the discomfort of being seated in general and prolong the time of being seated without causing any
damage.
If the biomechanical aspects are clarified first of all, the therapist then may consider which of the possible wheelchair features may be necessary to meet the other needs of the individual.
2) THE IMPLEMENTATION ASPECTS RELATED TO THE CONTEXT IN WHICH THE WHEELCHAIR IS GOING TO FUNCTION.
To prescribe a wheelchair is not only about providing an assistive device, it is also about how to use it at home in the context of an everyday life (Kraskowsky LH 2001, Reid D 2002, Clark
FA 2006). It is crucial that a concrete, practical education and instruction is carried out as the device is applied. Perhaps the user himself is capable of implementing a suitable use of the wheelchair – perhaps it is necessary to instruct some family members or some assistants.
The therapist must be sure, that the process of “getting into a seated position” and “staying in a seated position” is harmless and safe – both in relation to risk of tissue injury and in relation to development of e.g. contractures and scoliosis .
For instance this means that the transfer process and the right use of the sling as a body support unit of the hoist can have great influence on the process of getting into a wheelchair and on staying in a seated position in the wheelchair. The way to remove the sling without disturbing the stability of the pelvis and the exact point of contact with the back of the wheelchair is of great importance and is in no way an obvious matter to the user or the assistants.
The therapist must be very precise and competent in guidance and supervision concerning the different assistive devices to be used in combination in the individual’s everyday life.
There is a need for enough time to do so and to do it in the users´ home. Often repetition and follow up will be needed (Garber SL 2000).
3) THE EMPOWERMENT ASPECTS.
- meaning to meet the users’ whishes about living an everyday life meaningful to him by participating and doing activities of daily living.
It can be of great importance to meet the user with a client centered approach in order to empower the wheelchair user to take responsibility for his own health. It means to be empowered by the professional therapist with knowledge of practicing activities safely (Sable JR 1999, Schubart JR 2008).
The point is that wheelchair users – as other people - wish to practice fulfilling activities of daily living. But doing so from a wheelchair sometimes involves risk of structure or tissue injuries. OT’s or PT’s may guide their clients in order to find strategies less harmful to the body. The challenge is to provide sufficient support without compromising function and to promote activity and function without causing damage to the body. If there is a risk of causing damages OTs or PTs should assist the user in finding other ways of practicing activities. If the professionals do not intervene sufficiently it might have serious consequences to the user in finding his own new ways of practicing risky or damaging activities.
An example of a seating assessment process model
To be able to carry out a systematic seating analysis of the individual a model of a seating assessment would be suitable. The following model is one way to enlighten physical, psychological, social, contextual, and environmental aspects of the individual (Jensen EM 2003). The steps do not necessarily come in line, but the process consists of these following steps:
1) Description of the most important problems of activities concerning self care, work and leisure time regarding the wheelchair from the users’ perspective.
2) Relevant theory, literature, diagnoses, legislation, references, test-tools et cetera has to be investigated and documented to make sure that the practice is based on evidence where it is possible.
3) Identify components concerning context, activity and participation in everyday life, ability of function, capacity and performance for instance:
- Physical examination and measures of the user - Joint motion, sensibility, tonus et cetera
- Identification of the user’s posture in the coronal, the transverse and the sagittale plane
- Potential of rehabilitation
- Possibilities of attaining a functional and stable seated position without any risk of pressure ulcer development or other physical injuries caused by the seated position
- Conclusion of the sitting ability using a relevant tool. There are several clinical assessment tools for posture, alignment and postural ability (Rodby Bousquet 2008).
- Conclusion of contextual factors.
- Description, identification and evaluation of the previous seating-assistive devices.
4) Analysis of data concerning resources and possibilities of rehabilitation of the individual, for instance:
- Functional demands concerning the wheelchair
- Functional demands concerning any transfer situation into the wheelchair
- Meet the needs of body position changes with the relevant features including evaluation of the interaction between the wheelchair features of tilt, recline, elevating leg rests and centre of gravity.
- Meet the needs of stability and pressure distribution of the body with an orthotic match between a stable individual posture and the wheelchair. Include evaluation of possible consequences of using features like tilt, recline and elevating leg rests in combination.
- Meet the needs related to the surroundings.
- Highlight critical factors.
5) Determination of goals, conditions of the effort, and plan the action:
- Make an activity profile of the user
- Clarify the goal of the user, the assistant, the therapist and perhaps other professionals involved.
- Negotiation of common goals, and if necessary renegotiation.
- Planning the testing and assessment trial of the wheelchair and the features 6) Implementation of the plan of action.
- Testing and try out of the wheelchair and relevant features.
- Instruction and education of the user, the assistant and other relevant persons.
- Identification of fresh activity problems arising from the expected use of a new wheelchair.
7) Evaluation and follow-up.
Best practice regarding tilt, recline and elevating leg rests
The meaning of these features is to supply and bring support to the body and to make it possible to adjust the position (within a limited range of motion).
These adjustments provide possibilities to change the impact of gravity on the body, to use gravity for stability and to alter the pressure on the tissue.
Let us take a closer look at the application of these features clarified during the systematic seating assessment process. Their effect on the body is largely dependent on:
• The construction in relation to the wheelchair,
• The way the user fits in and is sitting in the wheelchair
• The specific individual needs related to the users’ functional ability and progression
• The relation to the specific activities in which these features are to be used.
The use of most of these devices, have implications on one or several joints of the user.
In order to achieve a clear movement in a joint, the feature axis of rotation should be in the exact position of the anatomic joint axis of the user. If this is not the case, the movement of the feature will influence the
user with unintended consequences like involving movements in other joints, shear forces and possibly development of unintended compensating strategies in other parts of the body.
For that reason it is of great importance to the therapist to be sure that the affect of the feature relates to the goals of the seating assessment. The therapist must of cause test the feature on the wheelchair together with the user to exclude possible unintended side effects. These side effects may be different in different wheelchairs.
Definitions and guidelines
When it comes to seating assessment we operate with some terms to be defined as background knowledge in this paper:
Friction: is a force that acts parallel to a surface as pressure acts perpendicular to a surface. Friction is acting on the skin and is truly causing superficial damage (Berlowitz DR 2007).
To sit according to ICF: d4153 maintaining a basic body position in sitting. Staying in a seated position, on a seat or at the floor, for some time as required, such as when sitting at a desk or table.
To be seated according to ICF: d4103 Sitting -getting into and out of a seated position on a chair with or without the use of assistive devices and changing body position from sitting down to any other position, such as standing up or lying down.
To move the whole body from one place to another:
ICF: d455 Moving around - moving the whole body from one place to another by means other than walking.
ICF: d465 Moving around using equipment. Moving the whole body from place to place, on any surface or space, by using specific devices designed to facilitate moving or create other ways of moving around.
Transfer: Move the body from one place to another with or without specific assistive devices.
Postural ability: is the ability to balance and stabilize under static and dynamic conditions and change posture and position as required (Pope 2007). There are several clinical assessment tools for posture, alignment and postural ability. (Rodby Bousquet 2008)
Posture: is the arrangement of body segments in relation to each other and to the supporting surface (Pope 2007, Kell 2005).
Stability: Requires a large base of support and a low centre of gravity that falls within the base of support.
Pressure: is a force acting perpendicular to a surface. It is often measured with pressure mats to
demonstrate the forces acting in the interface between the body and e.g. the cushion. This kind of interface pressure mapping is not at all able to measure the forces acting in the deep tissue layers, as it is still not possible to measure the shear-forces nearest to the boney prominences sufficiently by this tool (Oomens CWJ 2003, Gefen A 2007).
Pressure ulcers: is a common term of all kinds of tissue injury related to pressure, friction or shear. There is no separation of pressure ulcers caused by the lying position or the seated position. It seems to be of relevance to separate the different kind of pressure ulcers as regards of the reasons and the location.
Pressure ulcers related to the seated position is exposed by a considerable amount of increasing forces than in the lying position caused by gravitational pull of the body.
The etiology of pressure ulcers is dominated by 2 very different hypotheses. One is based on the hypothesis that tissue necrosis is caused by ischemia. Another one is based on the hypothesis of deformation of the muscle cells. Gawlitta et al have investigated the two hypotheses and found that ischemia does not lead to tissue injuries within the first 22 hours, while compression and deformation leads to cell death within few hours (Gawlitta 2007, Gawlitta 2007).
Shear: is a force that acts parallel to a surface as pressure acts perpendicular to a surface. Shear is acting in the deep tissue layers near the boney prominences of the pelvis near the ischii tuberosities.
Sitting-acquired pressure ulcers:
Sitting acquired deep tissue pressure ulcers (DTI) appear to be a very much more serious threat to the body than pressure ulcers related to the lying position in bed. The risk of sitting-acquired pressure ulcers is of high relevance to the therapist working with seating assessment and adaptation of assistive devices like wheelchairs and cushions.
Most sitting-acquired pressure ulcers are the result of deep tissue injury close to the pelvis and most lesions that are truly superficial are caused by friction and actually not by pressure (Berlowitz 2007).
The basic mechanism causing pressure ulcers is still not fully enlightened and a lot of investigation is going on with this subject. Nevertheless some experiments measuring support forces in different seated positions significantly have affected the force distribution on the seat (Bush 2007).
For that reason the therapist has a very good clinical reason for taking care of the prevention of sitting- acquired pressure ulcers while we are waiting for the basic mechanism to show up.
This can be done by the means of biomechanical resources from the pelvis and the spine:
• To stabilize the trunk with the wheelchair in the sagittal and the coronal plane using the possibilities of the wheelchair to adapt to the individual body by giving support to the area including the spina iliac posterior superior.
• To minimize the forces of shear in the tissue and friction on the skin as well as
• To optimize the pressure distribution area on the seat.
This can be done by articulation of the trunk if the body is able to do so and by using tilt in space – a feature of the wheelchair that could be very relevant to choose.
Tilt in space
Tilt is in the RESNA paper defined;
“Tilt systems change seat angle orientation in relation to the ground, while maintaining the seat to back and seat to leg rest angels. Traditional tilt operates in the sagittale- plane, while lateral and rotational tilt systems operate in the coronal (frontal) or oblique (transverse) planes respectively”
Figure 1 Tilt features make it possible for users to alter the impact of gravity on their body.
How does gravity influence wheelchair users that are unable to change their own posture?
Although it is not recommended, wheelchair users often sit in their chair all day, maybe up to 15 hours a day 11.8+/-3.4 hours (Ding et al 2008). This represents a huge challenge, because within this timeframe the user may need to accommodate and alter his trunk position for activities of daily living.
Most wheelchair users are unable to change position without risking body or tissue injuries. The ability of the wheelchair user to align and stabilize the body against gravity may also be reduced to some extent. This is the case when the body deviates from the midline, or the head falls forward – here gravity reinforces the deviation, causing the body to buckle and bend.
An asymmetric or crouched and slumped posture increase the risk of development of secondary
complications such as tissue adaptation, contractures, hip dislocations, aberrant spinal curvatures, tissue injury, pain and discomfort (Pope 2007). To increase function and minimize the risk of secondary
complications there is a need to align and stabilize the body segments and control the forces acting on the body (Kell et al 2005, Pope 2007) by providing appropriate support and sometimes using a tilt in space in order to use gravity to stabilize the body and alter the pressure on the tissues (Michael et al 2007). In neuromuscular diseases arm function is most often reduced when using tilt in space.
Range of movement
Most tilt systems operate in the sagittal plane, but they come in a variety of constructions.
Posterior tilt is generally speaking defined as a tilt from the neutral horizontal seat position and back.
Anterior tilt is generally defined as a tilt starting from neutral seat position and forward.
The range of movement in tilt varies a lot. Most tilt devices have a range between -5 to +20 degrees tilt.
Others have a wider range and can have a range up to 45 and 60 degrees. Clinical practise shows that some users need at least 35° tilt to reach a satisfactory weight distribution on the back. This means that for some users the standard range of movement of tilt is not enough.
What is the effect of the use of tilt?
In a systematic review SM Michael, D Porter, TE Pountney (2006) for non-ambulant individuals with neurological and neuromuscular impairment the clinical effect of tilted seat position is studied. They formulate their findings in the following clinical messages:
• Evidence is lacking on the effects of tilted seat positions on health, function and participation outcomes.
• Studies of progressive neurological populations are particularly scarce
• There is some evidence to suggest that a posterior seat tilt reduces pressure under the pelvis for people with neurological impairment
In other words posterior tilt is to some extend able to reduce pressure under the buttocks and the Ischia Tuberosities. There may not be much documentation today on the long term effect of the use of tilt but there is no doubt that adjustments in posterior tilt alter the impact of gravity on the user in somewhat the same way as able-bodied users change their sitting position during prolonged sitting.
Anterior tilt is generally used in office chairs for able-bodied persons, in order to support an active upright sitting posture.
Prolonged use of anterior tilt must be carefully considered before it is recommended because of the instability of the body and the tendency to slide forwards on the seat. There is an obvious risk of
development of high shear forces being seated in this way and it may have crucial effect on the user with no sensibility and may cause pain over time to the user with intact sensibility but low sitting ability.
Anterior tilt function can, dependent on the construction, reduce the seat height in front making easier to reach the floor for standing transfers. It can be tempting to use the anterior tilt to adjust to a low table or to shorten the total length of the chair in elevators etc. But one has to be aware of the time spent in this position and reposition the individual after having been seated like this. Do not use anterior tilt to get to standing to weak persons with neuromuscular diseases.
Anterior tilt function may need to be combined with recline-, seat elevation- and elevating leg rest features to make the individual able to adjust the active sitting posture. The use of additional utilities as knee support body/chest electrical belt or hip belt may be considered.
If the anterior tilt is an inborn feature of the wheelchair therapists may in some cases consider dismounting it because of the possible risk of injury for some user groups. It could be a risk if the anterior tilt would be used unintended. If the anterior tilt is dismounted it can often mean an increase of the posterior tilt range.
The impact of the tilt function on the body is much dependent on the construction. The movements provided of the tilt are largely based on where in the construction the mechanical axis of rotation is placed.
It is therefore important for therapists to have knowledge of different constructions of wheelchair models as well as knowledge of the obtainable degrees of anterior or posterior tilt. It all depends on the findings of the systematic seating assessment skills.
Tilt and the impact of altered gravity on the user.
Some groups of users may be sensitive to movements or changes of posture due to poor postural ability, muscle weakness or altered tone. The less postural control they have, the more sensitive they may be.
Changes in muscle tone occur as the body is placed in different orientation in space relative to the vertical plane.
Among users with brain injuries that are posterior tilted, causing the head to move towards supine, a dominating Tonic Labyrinthine Reflex may increase extensor tone. Changing orientation also affects righting reactions and other neurophysiologic responses complicating the change in tone. (Herman JH, Lange ML 1999)
On the other hand for some users tilt can lead to more inhibition. Among users with brain injuries there appears to be little consistency in positions that promote inhibition pattern.
It requires careful examination by therapists to find out which position is contributing to increased tone and which positions are relaxing and inhibitory (Herman JH, Lange ML 1999).
Excessively posterior tilt is sometimes associated with limited possibilities for communication, upper limb function and the ability to stand up from the chair. (Pountney et al 2004)
Posterior tilt may be used as a strategy to get a better head balance. A large degree of posterior tilt however, can be challenging to balance the head. In these cases the need to support the head with a headrest must be considered.
The therapists need to observe the effect of the tilt on the user; this also means that they, in a much larger degree, need to document the pros and contras in their findings in every single case.
Tilt may, on some users with body deformities and reduced breathing capacity have an impact on organ function such as respiratory function, pulse and blood pressure etc.
In these cases it is advised to closely observe how the individual user is coping with more excessive tilt.
In cases where the respiratory functions are at risk of e.g. scoliosis and pneumonia it may be advised to measure the O2 saturation and hart rate with a pulse ox meter. In neuromuscular diseases FVC is measured and is the most used indicator for measuring influence on lung function when changing body position. In this way one can apart from clinical observation, get a more objective measurement to compare the outcome in both upright sitting and in an excessive tilted position.
Orthostatic hypotension is generally associated with the fast movement from sitting to standing, but can also be experienced in tilt changes.
Users where the joint axis of the shoulders and pelvis are not parallel to the sagittal plane (pelvic rotation) are often positioned in moulded seats.
Figure 3 Special care must be taken as to how the seat is mounted on the chair.
In figure A the position of the user is OK both in upright and tilted position. The position of the user in figure B is OK in the upright position, but this position will lead to an unbalanced, sideways posture in tilt.
Affects of tilt on manual wheelchair propulsion
Because tilt has an effect on the overall weight distribution and the position of the trunk and arms, the manual wheelchair propulsion can be altered. This hypothesis was confirmed in a study (Aissaoi et al 2002) on self-propelled older wheelchair users. The result showed significant positive effects on biomechanical efficiency in tilt. These results were not found in reclined positions for this user group.
Lateral tilt
The RESNA paper defines lateral tilt as follows:
“Traditional tilt operates in the sagittal plane, while lateral and rotational tilt systems operate in the coronal (frontal) or oblique (transverse) planes respectively”.
This means that lateral tilt adjusts the seat sideways (see figure 4).
Seeking lateral (asymmetric) support is a one of many strategies in normal sitting behaviour that users may develop to cope with (long-time) sitting. But active lateral tilt in wheelchairs is, however, seldom used. The efficiency of lateral support is closely related to the (lateral) support surface built in the backrest. Already minor lateral adjustments can have positive effects on function, weight distribution and mealtime management. (Clements et al 2004) and raising comfort level (Hardwick K Stewart S 1994)
In some cases active lateral tilt adjustments may be considered used to facilitate head control and get the head in midline but should be user controlled. It is therefore somewhat strange that lateral tilt devices are so rarely used.
The effect of lateral tilt is not really documented. There are examples of single case studies that report of positive interventions with lateral tilt (Clements et al 2004) (Hardwick K Stewart S 1994). Positive outcome like these should be a major challenge for users, therapists and wheelchair constructors to find out more about the effects of using a lateral tilt function.
Tilt feature control
Because tilt movements by the user can be experienced as challenging it is important that they can be operated independently by the user himself.
To be sure the user has control of the device and features a systematic cognitive and functional assessment should be considered in order to establish the need for direct choice function control instead of the far more complicated joystick menu controls. If the user is unable to control the tilt and is dependent on others, there is a need for both instruction and education of the care-givers around the user.
As tilt can have both positive and negative consequences for the user it is absolutely necessary to offer the user or the carers’ appropriate training and instructions to be able to use these functions according to the specific needs of the individual. If this is not done properly devises may not be used or may be used in a wrong way.
The assessment of the functional needs of the user and the practical evaluation in a tryout setting, will show the necessity to which the tilt function needs to be combined with other features like recline systems, elevating leg rests and seat elevation.
Recline of the backrest
The RESNA-paper defines recline as:
“Recline systems provide a change in seat to back angle orientation while maintaining a constant seat angle with respect to the ground.”
From the definition we can conclude that:
The seat angle with respect of the ground does not change.
The effect of changing the seat to back angle will change the users’ hip angle.
Changing the hip angle will subsequently alter the impact of gravity which may have consequences for the stability of the chair.
Range of motion in backrest recline
There are various designs and models of the backrest recline that vary in the range of motion. The needs of the users vary but if the goal of the recline system is to give pressure relieve the recline angle should be around 90-120 degrees in combination with tilt in space. A study (Springle S, Sposato B 1997) found that the biggest reduction in maximum pressure at the Ischia Tuberosities was found at 45 º tilt in space and 120º recline.
Recline systems can be both manual-and powered controlled as described under the tilt-part in this paper.
Transfers in and out of the wheelchair
A backrest in recline may be helpful when the user is seated because a reclined backrest allows the user to be placed as far into the chair on the cushion as possible. In the same way a temporally maximum reclined backrest makes it easier to put on clothes, hoist sling etc.
Different backrest recline devices
In normal recline constructions the back of the user moves in relation to the backrest during recline. This movement is not intended, but is a side effect that creates shear forces in the body and friction forces between the user and the chair – both on the buttocks and at the back. Shear forces on weight bearing tissue is one of several risk factors for serious tissue breakdown.
These movements may not be present in constructions where the axis of rotation of the recline device is in the exact position of the anatomic joint axis of the hip joints of the user. (See figure 5 and picture 1)
Figure 5 An example of a construction where the axis of rotation of the device is placed close to the anatomical hip joint.
Users who cannot correct their trunk position and reposition themselves without causing shear or friction need assistance to be repositioned back into the chair after using the recline feature.
The impact of these negative side effect movements are increased when lateral support and headrests are mounted on the backrest, because they too will move relative to the user. Besides the function will be missed of specially designed back support, side support and head support.
This means that therapists should be aware of the impact of these side effects in all kinds of recline
features because coming up from a reclined position the user may very well experience to be pressed down and forward by the backrest moving up. It makes it necessary to reposition the body relative to the
backrest of the chair and the cushion.
These side effect movements create shear forces on the weight bearing tissues. Shear forces on weight bearing tissue is one of several risk factors for serious tissue breakdown.
Some wheelchair manufacturers have alternative recline systems (sliding backrest) available in cases where the impact of the side effects of the recline system is not acceptable for the user. (se figure 5)
The construction of sliding back creates automatic, parallel, length compensative movements in the device.
These mechanically compensative movements reduces the impact of the negative side effects when the backrests recline
A recline system influence various other functions of the wheelchair and it is necessary to assess several possibilities.
Key factors (Minkel J 1992) that can be recognised in choosing a recline system are:
• Client’s ability to adjust his position to overcome the effects of shear
• Need for independently moving features
• Method of access to control recliner- and other features
• Finished seat height from the floor
• Battery access
• Stability of the wheelchair
• Turning radius
• Cost
Each of these factors should be carefully assessed and evaluated in order to find the right solution for the individual user.
Several of these factors are discussed elsewhere in this paper.
Recline in combination with tilt in space
For many persons with neuromuscular diseases it is necessary several times during the day to reduce the negative influence of the gravity forces on the spine by resting backwards in the wheel chair. To reduce the risk of sliding of the body when getting into resting position, always start using tilt in space and then use recline. And when returning to upright sitting position always start with recline and then tilt in space.
Recline and the stability of the wheelchair
The stability for the wheelchair may be affected by recline (and tilt) systems because of the effect on the overall weight distribution. Most power chairs reduce the driving speed automatically when tilt or recline adjustments reach a critical point for the stabilisation. The instability may cause the chair to tip backward when going up a ramp, curb cut or hill. This is especially the case in manual wheelchairs and the (in) stability should be tested in max tilted or reclined position in every single case.
Most wheelchairs may be adjusted (extended length base) to improve stability. This should only be done by the wheelchair supplier, or other qualified personnel.
The stability of the wheelchair is also challenged by environmental factors like:
• Pavements and kerbs
• Slopes
• Soft ground
• Thresholds and small obstacles
• Ramps
• Transport
(Guidance on stability of wheelchairs Department of health MHRA DB2004).
Finding the right combinations of powered mobility and a powered backrest recline feature can vary and must be determined in the assessment and systematic analysis of the needs of the user.
Elevating leg rests devices
In the RESNA paper, elevating leg rests are defined:
“Devices that allow individuals to change the angle of orientation of the legs and/or footrests relative to the seat, extending the knee”. Some of the leg rests are articulating, which means they lengthen while also extending the knee.”In order to provide a clear movement in the knee joint the fulcrum of the device should be as close to the fulcrum of the knee joint as possible. A lot of features on the market are
constructed with the axis of rotation below and/or proximal to the knee joint. If a device like that is brought up, stretching the knee, the device will not only move the knee joint but it will also slowly lift the thigh from the seat and thereby affect the hip joint, the ankle joint and alter the pressure on the Ischia Tuberosities (Patterson et al 1989) In this position the device will cause discomfort and even worse perhaps pressure ulcers and will in addition mean difficulties for the user to maintain the seated posture (Figure 6).
Figure 6 Effects on different mechanic axis of rotation for elevating leg rest adjustment.
Some of the manufacturers have indeed tried to locate the axis of the device close to the anatomic joint axis; others have as implied in the second part of the definition constructed automatic, parallel, length compensatory movements in the device. This kind of construction does not influence the sitting posture in a harmful way.
The height of the cushion is an important factor as it may influence the position of the knee joint in the chair!
The definition used by RESNA does not describe how the change of angel is achieved. Some features are adjusted manually controlled by the user or his assistants and some are adjusted electrically.
Some of the features allow separate control of both legs rests. Others move both legs simultaneously. For users with asymmetric needs it may be important to adjust one leg separate from the other. Simultaneous movements of both legs may cause compensatory movements in other parts of the body as cleared up through the seating assessment process.
Range of movement
In the RESNA definition there is no specification of the degree of adjustment of range of movement related to the knee joint.
As the range of movement in the knee joint can be limited, it is important to assess the possible limitations in the range of movement in both knees of the user. In what range of movement the feature allows the knee angle to be adjusted is partly dependent on the construction and is therefore different for each wheelchair supplier and model.
Some users need almost full extension in the device because they need to push against the footrests in order to get back into the seat. This function is not recommended for users in risk of developing pressure ulcers.
Others need as much flexion in their knees as they can get to accommodate and to come forward in a more upright seated position. Using the footrests as much as possible as a redistributing area depends on 90 degrees of flexion in the knees. The free position of the feet, allowing + 90 degrees knee flexion is underlined in the studies on a ‘functional sitting position’ (Myhr & von Wendt1991,1993 ) and (Myhr U 1994)
Users with short hamstrings have a tendency to slide forward in the seat. The short hamstrings forces the pelvis into posterior tilt, flattens the lumbar lordosis and increase the kyfosis. Therefore they accommodate for more knee flexion to avoid high muscle tone in the hamstrings. Stretch on hamstrings on seated
position may lead to compensative side effects such as: posterior tilt of pelvis, loss of the natural spinal curves and a risk of developing kyfosis (Kirkwood CA, Bardsley GI).
Adjustments made with elevating leg rests should be critically observed because they may affect the sitting posture. Therapists and users (and their carers) should be aware of both the positive and negative effects on the sitting posture, the distribution of pressure and stability.
Transfer in and out of the wheelchair
The leg rests can cause trouble and unsuitable transfers as the user need to be seated as close to the wheelchair back as possible to be stable in the seated position.
The constructions of the various elevating leg rests are different and this may have both positive and negative consequences in the transfer situations. That is why it is important to try out the transfer in practice.
Elevating leg rests as part of combined devices for specific functional purposes
In some wheelchairs the elevating leg rest devices are combined with other devices, for example;
Power lengthening footrest features, anterior tilt and backrest declination in order to provide a power - From Sitting to Standing Support- function.
Another example of combined (manual) devices is used within the concept of “dynamic seat” that is developed to provide greater personal freedom and to prevent secondary injuries to wheelchair users with high extensor thrust.(Seong-Wook Hong et al 2006) (Cooper et al 2001).
Conclusions
The purpose of this document is to bring forward ideas and create a background for discussions concerning best practice and to provide recent evidence from the literature to support the practitioners.
Seating is a very complicated matter with no simple answers. It has indeed been a very challenging and ongoing process. As one can observe the use of these wheelchair features from very different angles it can lead to different priorities.
The paper has no intention to illuminate every single problem.
The OTs and PTs responsible for individual prescription of wheelchairs may hopefully find some useful ideas from the paper to meet the needs of the individual and to choose the best wheelchair-features and
adaptations in every single case.
The purpose is to draw attention to the different advantages of the features and on the other hand to prevent different kinds of physical damage caused by unsuitable or unintended use of the assistive devices.
To be sure when to choose the features of greatest importance and suitability the therapist must carry out a thorough assessment to identify the needs of the individual as a core element of the seating assessment process. Not until then, it may be considered which of the wheelchair features that would be relevant to the specific individual.
Definitions and guidelines are described starting from the clinical experiences of the group members. We have made an effort to reach some kind of consensus and have to some extend achieved the purpose, but there is of course room for further improvements now and in the future.
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