FAQs for Therapists
Here are our frequently asked questions for therapists.
Why should I use a Caps seating system?
The Caps seating system design has a strong, solid research base. It was designed, developed and produced in response to years of research into postural management at Chailey Heritage, and has proven its effectiveness over years of clinical use. The design is constantly being developed based on the original research findings, and remains a clinically effective tool promoting the best positioning possible, with the exception of a therapists hands.
Chailey Heritage Clinical Services are longstanding leaders in the field of research and development, providing treatment, services and provision of postural equipment for children and young adults with multiple moderate to complex disabilities. Active Design Ltd manufacture the Caps seat, the Chailey lying support, and the Chailey standing support, which are all specifically designed to promote and enable maximum functional ability, and provide developmental opportunity for people who need it. It is within this dedicated knowledge base that the Caps ll seating system is founded.
What is the theoretical background of Caps seating?
The Caps II seat is produced to a design based on detailed research into seating and posture at Chailey Heritage in East Sussex. ( Mulcahy et al, 1988. Adaptive seating for motor handicap: Problems, solutions, assessment and prescription. British journal of Occupational Therapy.)
Many other seating systems are based on similar principles to Caps seating, but because the Chailey approach is on based on research that defines the components needed to provide postural stability and control, the Caps seat will ensure the child’s postural ability is increased, providing the potential for better function.
Information gathered with the postural assessment tool informs the prescription of components of the seating system which work for each individual child, ensuring that the Caps ll seat proves its effectiveness when you see what they can do in it.
The theory that underpins the skill acquisition that the Caps seating is based on is the dynamic systems theory. (Turvey et al.1982 ) This framework explains that postural control is developed though the interaction of several different systems, the nervous system, the musculoskeletal and the environment, and development will be limited by the slowest developing component.
The ergonomic configuration of the Caps system aims to influence the biomechanical forces affecting the body. By using the philosophy of freezing degrees of freedom to influence postural and motor ability, the person can develop and practice normal movement patterns in a controlled manner.
Caps seating provides clinicians with the practical tools to use evidence based practice.
Seating specialists and indeed healthcare professionals in general are being questioned ever more strongly by providers regarding the theoretical basis on which they prescribe for their clients. There is a drive to provide measurable outcomes and evidence based practice for all healthcare clients. The field of specialist seating and wheelchair seating provision is without a strong research base on which professionals can rely and plan their intervention. It therefore becomes even more imperative for clinicians to seek out and provide the best possible options for treatment and equipment based on the research which is available to them.
Frameworks such as the International Classification of Functioning, Disability and Health, guide professionals to consider a client’s activity and participation goals as outcome measures, and not focus only on their impairments. Improved postural stability should be the background to any activity a person wants to achieve.
The research clinicians at Chailey Heritage Clinical Services have developed and produced a validated assessment tool, formulated from years of clinical intervention and knowledge gained from practice and experience, and this is critierion referenced to a normal model of motor development. This assessment tool is called The Chailey Levels of Ability (The Chailey Approach to Postural Management. T.E Pountney et al 2nd Ed 2005.)
By understanding and utilising the Chailey Levels of Ability, healthcare professionals can monitor and measure a child’s developmental progress in lying, sitting and standing. Clinicians can use the tool to guide assessment and subsequent treatment and equipment provision for children, justifying treatment and expenditure on 24 hr postural management for their clients. This assessment tool is widely known, accepted, used and recognised. (www.activedesign.co.uk/training )
By linking the use of the Chailey Levels of Ability in their treatment practice to prescribe the most effective equipment for each individual, clinicians can ensure the products they select are based on sound evidence and best practice.
The equipment designed and used at Chailey Heritage Clinical Services 24hr postural management is available to purchase from Active Design Ltd. All the Minicaps and Caps ll seats are manufactured in their workshop in Birmingham.
Caps seating allows control of major key points of the body
Most paediatric therapists and those specialising in neurology will have an understanding of normal movement and postural key points. It is well documented that foetal reflex patterns and mass motor patterns are inhibited over time and replaced by the development of learned normal movement patterns. (Pretchtl 1984)
During normal development of balance and posture, the major key points of the body are gradually positioned and stabilised through random movements into normal postural sets, these provide the starting points from which the body can cognitively promote and facilitate functional activity against gravity. (Hadders Algra 2006) Voluntary motor patterns, are then learned and practised within these set parameters until the movements become automatic and can be performed requiring little cognitive effort from the brain. (Pountney et al, The Early Development of Postural Control, 1990)
Caps seating through its specialist design allows a child to be positioned to align their key postural points. The child can then experience the optimum posture of midline symmetry which is part of the normal developmental process, reinforcing a strong body image through sensory/proprioceptive integration.
The child will then learn to work/move volitionally from and through that posture, maximising neural reinforcement of the pathways using more aligned movement patterns with less effort. This provides potential to integrate the co-ordination required to achieve motor tasks. The ergonomic configuration of the seating, which gives increased postural stability to key points of the body, helping to neutralise mass patterns which may have been recruited because of a lack of stability, and therefore enable them to select more effective movement patterns.
How is the Caps II seat used?
By using a dedicated interface board the Caps seat can be fitted on to most wheelbases, powered chairs or pushchair bases. It can also be interfaced onto a high/low base for use in school or at home. Used as a static seat, it can allow one seating system to be used in various situations.
Caps II seats come in a range of sizes, individually produced, they can be prescribed to fit anyone, from the smallest paediatric requirements (Mini Caps seats) to large adult seats. If you have difficulty matching your measurements and selecting the size to order, Active Design, the manufacturers of Caps ll seating will assist therapists by providing a seating system with the best individual fit, to match the clinical needs of each individual client.
Some children require more than a standard curved backrest due to their postural instability. When their back profile is no longer symmetrical due to scoliosis or kyphosis, a flat backrest cannot accommodate these shapes and their stability is impaired. In these situations the child has insufficient contact with the backrest surface, and increased pressure around areas of altered shape.
Caps seating with a Lynx backrest can accommodate this clinical need. The modified adjustable backrest is individually moulded to support the best position the child is capable of, and provides a closer fit to the child’s back profile contours.
By moulding around the areas containing muscle bulking and controlling deformities with some degree of clinical correction, contact and trunk stability can be increased, pressure areas can be relieved, and some clinical correction can be achieved. This moulded backrest is provided if required by use of a moulding material called Lynx which is exclusive to Active Design.
What does a Caps seat do that other seats don’t?
The unique design of the Caps seating system with its integral sacral block and individually multi-adjustable knee blocks and footrests mean that a Caps system can give full pelvic control and leg alignment providing a balanced, neutral posture. It is the only system to hold the pelvis in such a supportive position, allowing control on all three planes; anterior, posterior and lateral, with discrete amounts of individual adjustment. This, and the ability to use a moulded backrest while still maintaining full pelvic control allows the Caps seating to be tailored to give the exact, clinically correct level of support required for each individual child, and make adjustments as the child grows and changes.
Caps seating promotes functional ability and developmental potential.
The seating works to promote and encourage functional movement and interaction with the social and physical environment around the child. The headrest and upper backrest promote midline position of the head, allowing chin tuck and facilitating isolated eye movements, as well as influencing the symmetry and position of an active shoulder girdle.
The thoracic laterals are adjustable for height and proximity to the trunk, giving increased stability and prompt to the sides of the torso. Harnesses are available to give additional sternal prompting if required. These should never be used tightly by pulling the child onto the backrest, and retracting the scapulae, as this will impair the child’s ability to develop shoulder girdle alignment needed to develop head and eye function.
The ramped seat positions the femora in a horizontal position and the flat area at the rear of the cushion provides a flat surface for the ischial tuberosities to balance the pelvis in neutral alignment. This increases trunk stability, whilst the sacral pad provides a block to support the pelvis and promotes a neutral pelvic position and prevents rotation.
Adjustable lateral hip guides provide lateral support to the pelvis to maintain it in midline, and control abduction of the thighs.
The Caps seating’s unique knee block design, with its individually adjustable kneecups, gives strong frontal support to the child’s pelvic girdle to influence good hip development, and support a neutral pelvic position, to encourage midline alignment of the trunk and pectoral girdle, allowing an upright, forward facing head position.
Good pelvic control is known to be essential to postural development. If the pelvis is stable and the feet and legs positioned correctly, pelvic control is much easier for the child to develop, and it requires less cognitive effort for them to initiate and establish control of the upper body and head.
Caps seat and kneeblocks are designed to maintain full pelvic control, even if the child requires a moulded backrest due to an asymmetric back profile. When stability is increased the person is able to switch attention to higher cognitive tasks such as their communication aid or driving using a joystick, as they no longer need to focus all their attention on maintaining postural balance.
If I am assessing using the Chailey levels of seating. At what levels would prescription of a Caps be appropriate and why?
Each clinician will have individual clinical opinions as to which equipment meets each level of clinical need. It is fair to say that the generalising of equipment provision is not appropriate, and experienced clinical skills are needed to select equipment to prescribe equipment on a ‘best fit’ basis.
A full clinical assessment should be performed, and physical/developmental goals set, family/carer needs, and environmental/lifestyle considerations addressed BEFORE equipment is chosen. Seating equipment should meet the task requested of it.
The benefits of Caps seating comes with its adjustability of prescription, its variety of accessories and its ability to be customised to meet the individuals clinical needs. It can therefore be used effectively to achieve general or specific postural goals for children functioning at all five Chailey Levels of Ability.
For instance a Minicaps with a Lynx back rest can be moulded to allow even the smallest, most severely affected child (Chailey Sitting Level 1: unplaceable ) to achieve an upright developmentally appropriate sitting posture, and promote functional ability.
In many instances a Caps seat will enable a child to achieve a sitting posture and seating tolerance, where all other seating systems have failed. Children with highly complex seating needs (level 1-3) benefit most obviously from use of Caps systems, with the excellent positioning and the full support at the pelvis, promoting neurological development and functional ability.
Even at the higher level abilities, children functioning at level 4 and 5 may still benefit from the Caps strong pelvic support, either to assist with controlling mass patterns or, when the child requires increased postural stability (such as when a child is driving a powered chair or being pushed over rough ground etc). This is because when under vestibular arousal, when balance is challenged, or when a child is tired, their postural ability deteriorates. It becomes more difficult for a child to maintain midline and control their sitting posture at these times, sitting and balance are then no longer under automatic control and require more cognitive effort. As sitting becomes harder the child will find it more difficult to concentrate on higher functional things such as learning new skills or concentrating on education. At these times a child will require increased postural support from their seating, and the Caps system will provide this.
Should I use kneeblocks on children whose hips are ‘at risk’, subluxed, or after bony surgery?
When using a Caps system the kneeblocks are an integrated part of the pelvic control. They provide an anterior support for the pelvis holding it in a neutral position and preventing rotation. Combined with the cushion, the hip guides, the sacral pad and footplates, the kneeblock helps to stabilise and position the femurs and control winds-weeping and subluxation, encouraging good alignment, hip abduction, and promoting hip development. Therefore a child with ‘at risk’ hips will actually benefit from kneeblocks which are correctly set.
There is evidence that the use of intermittent loadbearing encourages healthy bone formation, and joint movement promotes mature joint development, so support from correctly positioned kneeblocks has the potential to prevent hip displacement and encourage bone and joint development. ( K. Ward, C. Alsop, J. Caulton, C. Rubin, J. Adams and Z. Mughal, Low magnitude mechanical loading is osteogenic in children with disabling conditions, J Bone Mineral Res 19 (2004), 360–369.)
It is always advisable to request a consultant review or see a recent x ray if there is a difference in leg lengths without pelvic rotation, or if the hip appears painful. If the hip is reported as becoming displaced then it is crucial that the thighs be supported in a comfortable position to encourage hip integrity. The unique ability of the Caps knee block to adjust each cup individually shows its worth, as each hip joint can be controlled / positioned comfortably and independently.
An unstable hip should be placed in slight abduction, to improve the stability at the hip joint and encourage joint development. The kneeblock medial pad will achieve this, and the hip guide needs to be angled outwards slightly, but the kneecup itself on this side should not touch the patellae at the front of the knee. This maintains lateral control of the femur positioning, but prevents anterior pressure forces being exerted through the unstable hip joint. The hip on the unaffected stable side should be set up as normal providing the anterior pelvic control required. If necessary, should the hip be painful or the child have a lot of athetoid movement which could compromise the pelvic position and push the knee against the kneecup, it is possible to modify the knee block by using and a pommel/medial pad to position the unstable hip to maintain abduction, and use a single kneecup on the stable hip.
When would I use a pommel in a Caps system?
Children who lack postural control and cannot free their hands to reach and play, usually benefit from anterior pelvic support to give them better trunk control so they can try to use their hands actively. There are a few circumstances when anterior/frontal hold of the pelvis is not possible. If pain, pelvic asymmetry or deformity cannot be accommodated by lynx moulding, or prevents the child tolerating a knee block, a pommel can be used.
The Caps pommel consists of individually adjustable medial pads, which can be used to control adduction and maintain symmetry of the femora. Additional lateral control can be given if required, by mounting adductor pads from the footrest drop tubes to support the knee alignment on the outside of the knees.
What is a Lynx back and when should I prescribe one?
Lynx moulding material comes in a flat sheet that is made up of intersecting pieces of plastic links in rows which are adjusted, shaped and fixed by tightening a central allen key joint. The mesh type layout of the Lynx material allows the clinician to see and feel exactly the level of contact across the body surface. Each of the Lynx cross-links can be adjusted and repositioned easily, but once tightened, give a strong support for the pelvis and trunk, providing good sensory feedback.
The Lynx material works by being malleable in all directions during moulding, each joint can be compressed or expanded allowing it to conform to every curve, plane or contour in a back profile. This means that the material can be pulled out to accommodate muscle bulks or moulded in to support lordotic areas. By using the lynx to lift, stretch or control posture, deformities can be fully accommodated and supported, while aiming to improve stability and alignment.
Lynx backrests should be considered where a standard curved backrest does not provide full contact to the back profile. If a young person may need extra lateral trunk support because of a developing scoliosis, and this type of backrest gives extra possibilities to support a developing asymmetry and give more trunk stability.
Lynx can also be used to assist with learning head control, (in conjunction with therapy in prone lying), by initially moulding to allow the child to be fully supported with the central key point over the base of support and then gradually remoulding to a more upright posture as the child’s ability to hold its head against gravity increases.
When/Why are dynamic footrests used?
Many manufacturers of equipment suggest the use of ‘dynamics’ to prevent equipment breakage, however this should never be a primary aim in seating if the use of dynamics can affect postural ability and development. This is especially the case with paediatric clients, or where there is a high neuro-plastic implication in the clinical presentation.
Before provision of any dynamic component in a seating system, a child should be fully assessed to establish their ability in all postural sets (lying prone and supine, sitting long and box and standing) and their methods of transition through postural sets should be monitored carefully. This will allow full evaluation of the child’s postural ability and their ability to control tone and patterns of movement to function. Dynamic components can have a resounding influence on postural ability, this influence can be either positive or negative.
During assessment of the child’s posture attention we should focus on the child’s ability to select movement repertoires automatically (or volitionally) and which key points are leading/initiating the motor pattern. It is necessary to establish if the child has the ability within the seating to reposition or recreate the optimum position of symmetry in sitting when movement ceases. Dynamic components should only be prescribed when the child has the necessary skills and ability to cope with disruption to their postural stability.
Reinforcement of movement patterns through key points by practising the pattern against a resistance, is known to increase the ability to perform that motor pattern. If abnormal or mass patterns are allowed to be practiced and strengthened in this way, this will prevent the child experiencing developmental inhibition of the neural pathways, which allows the emergence of control to isolate movement components (fractionation) to create improved functional movement.
Distal key points are less influential in postural control than the primary key points. Therefore if dynamics are used only at distal points (feet via footrests ) it may be possible to reduce mass extension by allowing controlled discharge of the pattern without influencing the core postural ability.
In order to provide for reduction of mass extension in this manner Caps Dynamic footrests were developed. They are available in two types; the double plate spring type where the dynamic movement is very little and just allows for pressure relief and helps to prevent initiation of extension through plantar stimulus, and the dynamic telescopic type, where the extension is discharged through the footplate moving against a graded resistance.