Functional Posture

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Functional Posture Jane Chantry, Sarah Crombie CHAI L EY CL I NI CAL S ERVI CE S , S U S S E X C O MMU N I T Y N H S F O U N D AT I O N T R U S T, EAST SUSSEX, UNITED KINGDOM

CHAPTER OUTLINE Introduction��������������������������������������������������������������������������������������������������������������������������������������� 53 What Is Posture and Postural Control?������������������������������������������������������������������������������������������� 55 The Postural Control System������������������������������������������������������������������������������������������������������������ 55 The Neural System������������������������������������������������������������������������������������������������������������������������ 56 What Is Muscle Tone?������������������������������������������������������������������������������������������������������������������� 57 What Is a Reflex?�������������������������������������������������������������������������������������������������������������������������� 59 The Musculoskeletal System�������������������������������������������������������������������������������������������������������� 60 The Sensory System���������������������������������������������������������������������������������������������������������������������� 60 Feedforward and Feedback Mechanisms������������������������������������������������������������������������������������ 61 Impairment of Postural Control������������������������������������������������������������������������������������������������������� 62 What Is Postural Management?�������������������������������������������������������������������������������������������������� 62 What Is a Functional Posture?���������������������������������������������������������������������������������������������������������� 64 Assessment of Postural Ability for Functional Positioning Solutions������������������������������������������� 65 Gathering Your Information�������������������������������������������������������������������������������������������������������� 66 Medical Conditions Affecting Posture���������������������������������������������������������������������������������������� 66 Psychological Factors Impacting Posture������������������������������������������������������������������������������������ 66 Social and Environmental Factors Affecting Posture����������������������������������������������������������������� 67 Physical Assessment���������������������������������������������������������������������������������������������������������������������� 67 Using Measurement Tools������������������������������������������������������������������������������������������������������������ 74 Case Studies�������������������������������������������������������������������������������������������������������������������������������������� 75 Alan’s Case Study (Adult)������������������������������������������������������������������������������������������������������������� 75 John’s Case Study (Paediatric)������������������������������������������������������������������������������������������������������ 76 References����������������������������������������������������������������������������������������������������������������������������������������� 78

Introduction The ability to control our body’s position in space is fundamental to everything we do; even the smallest of tasks we undertake requires a degree of postural control and is therefore essential for successful functioning in everyday life. Children and adults with complex Handbook of Electronic Assistive Technology. https://doi.org/10.1016/B978-0-12-812487-1.00003-X Copyright © 2019 Elsevier Ltd. All rights reserved.

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neurological disabilities frequently display significant problems with their ability to control their posture and movements. For example, they may have difficulties maintaining a stable, sitting position without someone to hold them or the need to use their upper limbs for support. This means that in the sitting position, they are unable to use their hands for functional activities. However, provision of suitable equipment can assist in promoting a more comfortable, stable body position from which to achieve optimum functional ability (Pountney et al., 2004; Pope, 2007). Promoting posture for function can be viewed within the conceptual framework of the International Classification of Functioning, Disability and Health (ICF) (WHO, 2001, 2007). A person’s health condition may mean that they have body structures or functions such as contractures or deformities, abnormal muscle tone or gastrointestinal reflux, which affect their ability to maintain and control their posture. When considering how best to meet the needs of the child or adult, this framework helps us to consider the many factors impacting on the outcomes of any postural intervention. It will be important to consider what aspects of the person’s body structure or function are impacting on a functional posture, what activities the person is aiming to achieve through any change in posture and their goals for participation (Fig. 3-1). Personal factors such as choice of aesthetics may be important to the person (Goodwin et al., 2018), and factors such as family lifestyle may influence whether the equipment will be useful. Environmental factors need to be considered to ensure that the equipment can be used within the chosen environment (Huang et al., 2009); for example, there may not be sufficient space for a large powered chair within a home environment. With children, there may be additional factors such as parental choices, differing environments such as school or nursery and training of school staff, which may affect postural solutions. Without these considerations, the person may be provided with postural equipment that may be sufficiently comfortable or supportive,

Health condition, e.g., cerebral palsy

Body Structure and Function, e.g., spasticity limiting motor control of left upper limb, scoliosis

Activity, e.g., driving a powered wheelchair

Personal Factors, e.g., child’s behaviour

Participation, e.g., Playing wheelchair football

Environmental Factors, e.g., used in school only, home too small

FIGURE 3-1  Diagram adapted from International Classification of Functioning, Disability and Health (WHO, 2001).

Chapter 3 • Functional Posture  55

but not promote the function, participation or activities they desire. Provision of postural solutions for optimum function is therefore akin to a jigsaw puzzle; each piece is important to build the bigger picture and to achieve a successful outcome for the person. This chapter will first describe what is meant by the terms ‘posture’ and ‘postural control’, and which mechanisms impact on the achievement of an effective and functional posture. It will then explain why children or adults with neurological impairment may have difficulties with postural control. It goes on to explain what postural management comprises and the importance of promoting postural control and a functional posture. It discusses the important factors in the assessment process when considering a solution to meet the needs of a person’s posture and lastly discusses two case studies to demonstrate possible solutions for functional positioning.

What Is Posture and Postural Control? The term posture can simply be defined as the position of the body, or of body parts, in relation to each other and their position within space (Ham et al., 1998; Hadders-Algra, 2008). Our posture is continually changing as we shift in and out of varying symmetrical and asymmetrical positions, to complete and move between functional tasks and activities, in response to environmental factors and to remain upright against gravity. Postural control is the ability to remain upright, balanced and maintain control of a state of balance while performing a specific task or activity (Latash, 2008). For an individual with fully functioning sensory, musculoskeletal and nervous systems, this level of control happens almost completely at an autonomic level, and postural adjustments and changes, on the whole, occur without any conscious reaction or thought. However, it has been shown that there is a correlation between the complexity of a task being performed and the increase in attention required to maintain postural control (Reilly et al., 2008; Brauer et al., 2002). To understand why children and adults with complex neurological disabilities have such significant problems with their posture, we need to understand the mechanisms that provide postural control.

The Postural Control System There are two key functional goals of the postural control system: First, postural orientation; the ability to maintain the active alignment of the head, trunk and body segments with respect to gravity, the supporting surface and information provided through visual and internal feedback systems (Horak and Macpherson, 2011). Second, postural equilibrium/stability; the coordination of movement strategies to stabilise the centre of body mass during both self-initiated and externally triggered disturbances of stability such as required during a specific task or activity (ShumwayCook and Woollacott, 2001).   

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Somatosensory inputs Visual inputs Vestibular inputs

Postural Control Integrated Central nervous system

Muscle responses Muscle strength Range of motion

FIGURE 3-2  Factors influencing postural control.

This multifaceted and dynamic control system relies on a complex interaction between musculoskeletal, neural and sensory systems (Fig. 3-2).

The Neural System An intact central nervous system (CNS) is key to motor and postural control systems. The CNS is made up of the brain and the spinal cord and acts as the control centre for the body, integrating information and input from sensory receptors and controlling motor output in response (Fig. 3-3). The previously believed concept that posture is primarily the result of a reflexive activity (a motor response to a sensory stimulus that occurs spontaneously and automatically at a spinal cord level within the CNS) is now widely recognised to be incorrect. Postural control is a much more complex process involving virtually the whole of the nervous system (Hadders-Algra and Carlberg, 2008). The nervous system is made up of the following: • The spinal cord where simple reflexes occur, including automatic and stereotype reflex movements, and the peripheral execution level of movement. Central pattern generators for repetitive motor activities such as locomotion occur here. • The brain stem supports the body against gravity and generates gross, stereotyped movements and maintains equilibrium. • The basal ganglia plays an essential role in the initiation of most activities and the suppression of unwanted movements. It incorporates a number of feedback loops. • The cerebrum is the main centre for the control of voluntary movement, particularly complex motor activities such as the manipulative movement of the hand.

Chapter 3 • Functional Posture  57

Cerebrum

Brain Stem Cerebellum

Spinal Cord

FIGURE 3-3  Diagram of the central nervous system.

• The cerebellum is important for correcting posture and smoothing out movements. The medial zone in particular is involved in controlling posture and equilibrium, influencing the axial and girdle parts of the body, as well as the organisation of motor synergies (coordinated multijoint movements) (Latash and Hadders-Algra, 2008).    Each system combines to provide a base of axial stability for more distal mobility and skilled or refined coordinated limb movements. Damage to the brain and neural system often interrupts the flow of messages along various nerve pathways. This disruption of signals can cause changes in muscle tone, movement patterns and the retention or reemergence of primitive reflexes (Bobath, 1990; Carr and Shepherd, 2014).

What Is Muscle Tone? All muscles maintain a level of residual tension or resistance to stretch, even when relaxed and at rest; this enables them to respond and move quickly and easily when required. Without this tension, we would not be able to maintain and control an upright posture and resist the force of gravity; conversely, too much tension can lead to movement difficulties and other problems. This tension is known as muscle tone and is ultimately controlled by impulses from the brain and nervous system and occurs through a mechanism known as the stretch reflex. When a muscle is stretched, an impulse is generated in the muscle spindle and is transmitted via the sensory neuron to the grey matter of the spinal cord. Here the sensory neuron synapses (connects) with the motor neuron, and the transmitted impulse results in muscle contraction. While agonist muscles (prime movers) contract in response to stretching, antagonist (opposing) muscles must relax. Their relaxation is brought about via an

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inhibitory neuron within the spinal cord. Disturbances in muscle tone occur when there is an imbalance in the excitatory and inhibitory input to motor neurons, which is caused by damage to the spinal cord and/or the CNS. This damage then results in an imbalance between messages from the nervous system to the muscles causing altered excitability of this stretch reflex (Britton, 2004). Commonly seen disturbances in muscle tone include: Hypotonia or low muscle tone, where there is too little muscle tone at rest and muscle and joints may feel ‘floppy’. This is due to an abnormally low resistance to stretch as a result of too much inhibition in the stretch reflex arc. This may result in instability and lack of control of movement. For example, a person with low muscle tone in their trunk may have problems sitting upright for any length of time and may adopt a slouched posture (Fig. 3-4). Hypertonia or high muscle tone is where there is too much tension in the muscles and an abnormally strong resistance to stretch as a result of too much excitability in the stretch reflex arc. The muscle may seem tense and contracted even when resting. Spasticity is a condition where muscles are resistant to rapid stretching and results in muscle hypertonia and involuntary muscle contraction (Lance, 1990; Barnes, 2001; Ibuki and Bernhardt, 2007). Often it presents in specific muscle groups and can result in abnormal movement patterns and posturing. This can be seen in a common pattern of spasticity in the upper limb following a stroke (Fig. 3-5). Dystonia is a movement disorder in which involuntary sustained or intermittent muscle contractions cause twisting and repetitive movements, abnormal postures or both (Sanger et al., 2010).   

FIGURE 3-4  Child sitting on a box with a slouched posture demonstrating low muscle tone (Pountney et al., 2000).

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FIGURE 3-5  Diagram of a typical pattern of spasticity seen in a person after a stroke: note the flexion and adduction of the shoulder, flexion of the elbow, wrist and fingers.

These contractions resulting in torsion and twisting movements can be very painful. Similar to spasticity, dystonia may be focal (confined to one particular muscle group) or more generalised (involving multiple body segments and muscle groups).

What Is a Reflex? A reflex consists of a motor act that is elicited by a specific sensory input. Primitive reflexes appear at birth and become integrated as the motor system develops and more complicated movements emerge (Green, 2004). The primary purpose of the postural reflexes is to maintain a constant posture in relation to a dynamic external environment. For example, the postural reflexes need to develop and react to the presence of gravity due to the earth’s gravitational field. When the CNS is damaged, these primitive reflexes can again dominate motor activity and contribute to abnormal patterns of movement and posturing. Primitive reflexes that may be retained or reemerge as a result of damage to the CNS influencing an individual’s postural control are: Symmetrical tonic neck reflex. This is demonstrated by increased flexor tone in the upper limbs and extensor tone in the lower limbs when the neck is flexed, and increased extensor tone in the arms and flexor tone in the legs when the neck is extended. Asymmetrical tonic neck reflex (ATNR). This is when rotation of the neck and head causes extensor tone in the limbs on the face side and flexor tone in the limbs of the skull side. Positive support reaction. Pressure applied to the ball of the foot stimulates a full limb extensor pattern.

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Tonic labyrinthine reflex. This is a primitive and pathological reflex that is seen in totally involved individuals due to abnormal simultaneous contraction of extensors and flexors in the whole body. A flexed posture is exaggerated when the person is placed in the prone position, in which contraction of the flexors is predominant. An extended posture is exaggerated in the supine posture, in which contraction of the extensors is predominant (Shumway-Cook and Woollacott, 2001).

The Musculoskeletal System The musculoskeletal system provides form, support, stability and movement to the body, which are all inherently required for postural control. It is made up of bones, muscles, joints, cartilage, ligaments and other connective tissue; the integrity of these components is essential for their successful functioning. Problems with the musculoskeletal system could be congenital (i.e., present from birth) such as is seen in a condition called arthrogryposis multiplex congenita, a condition where contractures of the limbs are present from birth. Otherwise, it could be as a result of an acquired or developmental condition or disease such as multiple sclerosis, brain injury or muscular dystrophy, where neurological damage may cause the muscle to become denervated (loss of nerve supply) and immobile. Conversely, the nerve supply to the muscle might be overexcited and cause a limb to become immobile due to being in a constant state of hypertonia or spasticity. The long-term immobility of a joint or muscle can lead to muscle wasting, loss of muscle bulk, shortening of muscle tissue and eventually contracture of the muscle or joint. This loss of muscle strength, joint range of movement or muscle length will all negatively impact on the body’s ability to sustain balance and postural control.

The Sensory System The sensory system provides information to the CNS. The key sensory systems involved in postural control are: The somatosensory system: Proprioceptive, cutaneous and joint receptors provide information on the position of the body and the forces and pressures acting on the body in relation to the supporting surfaces. They also provide information about the relationship of body segments to one another. Proprioceptive sensory organs are located in muscles and tendons, or within the connective tissues (ligaments and capsules) of joints. These feed into the postural control system information regarding the status and function of the musculoskeletal system, with a constant flow of information to the spinal cord, the cerebellum and the brain. The most important sensory nerve endings for controlling the muscular system are the muscle spindle fibres and the Golgi tendon organs. Muscle spindles are found in the belly of skeletal muscles and provide the CNS with information regarding the length of the muscle and whether it is in a state of stretch. The Golgi tendon organs are found within the tendons that attach the muscle to bone and provide the

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CNS with information about the tension of the muscle and whether it is in a state of relaxation or contraction (Purves et al., 2004). The vestibular system: This provides the CNS with information about the position and movement of the head with respect to gravity and inertia forces. There are two types of receptors: •  Semicircular canals, which sense angular acceleration of the head such as in imbalance trips and falls. •  The otoliths, which sense linear position and acceleration and mainly respond to slow head movements such as during postural sway (Saladin, 2011). The visual system: The visual field and pathway are important regulators of postural control. Visual input provides information regarding the position and motion of the head with respect to surrounding objects. It helps to fixate the position of the head and upper trunk in space, primarily so that the centre of mass of the trunk maintains balance (Hansson et al., 2010).

Feedforward and Feedback Mechanisms The human body, in its structure, is inherently unstable and while maintaining balance and equilibrium are important, a static stable position is of relatively little use for function. A dynamic postural control system is required to make continual and adequate adjustments and meet functional demands. In response to ever-changing conditions, these adjustments are known as anticipatory postural adjustments and compensatory postural adjustments and work on a feedforward and feedback basis (Massion et al., 2004). Anticipatory postural adjustments: a feedforward system – Postural adjustments are anticipated and predicted and anticipatory forces are provided to minimise the expected disturbances. Compensatory postural adjustments: a feedback system – Disturbances in posture are detected by the sensory systems and are corrected immediately by postural reflex mechanisms called righting reactions (Fig. 3-6). In summary, postural control is a complex multisystem and dynamic mechanism influenced by: • The integrity of the nervous system. • Sensory processing. • Length-associated changes in muscles. • Selective control of muscle for posture and movement. • Bone and joint formation. • Biomechanical forces. • The environment. • The complexity of task.    Children and adults who have a developmental, neurological, motor or body structural impairment may therefore experience difficulties with their postural control.

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Central Command

Limb Movement

Feedforward for ancipated postural instability

Postural Adjustment

Postural Instability

Feedback for unancipated postural instability

FIGURE 3-6  Basic principles of postural control.

Impairment of Postural Control Disruption, damage or impairment to any of the systems involved in postural control will have an impact on an individual’s postural control mechanism to a varying degree. If the individual is unable to utilise normal mechanisms of postural control due to damage to either an immature brain as in a young infant, or a more mature brain as in an older child or adult, they will have difficulty controlling, organising and adapting movements in response to a task or environmental stimuli. They may be unable to change their posture and consequently spend a sustained period of time in a certain position without the ability to oppose the force of gravity. For example, tightness or shortening of particular muscle groups may have distinctive postural presentations; in a sitting position, tight hamstring muscles may pull the pelvis into a posteriorly tilted position and create a subsequent slumped spinal posture (Fig. 3-7). Similarly, we know that damage to specific parts of the brain during the course of a disease can also cause distinctive postural problems, such as is seen with the imbalance of dopamine and acetylcholine (both neurotransmitters) within the basal ganglia in Parkinson’s disease, resulting in a distinctive stooped posture, tremor and bradykinesia or reduced movements (Fig. 3-8). Any impairment of postural control can lead to a cycle of significant long-term issues, which in turn may lead to a further loss in postural ability. Thus, careful and timely management of posture is of benefit to address impaired postural control.

What Is Postural Management? Postural management is ‘a planned approach encompassing all activities and interventions which impact on an individual’s posture and function’ (Gericke, 2006). It has been advocated that to be most effective, it needs to be considered over a 24 -hour period (NICE, 2012). It should not just include the provision of seating and other positioning equipment, but encompass a more holistic approach through a wide variety of interventions, including: • Postural management equipment. • Individual exercise.

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• Orthoses. • Active exercise. • Botulinum toxin injections. • Surgery, both soft tissue and bony. • Analgesia/pain management. • Medications to control posture.   

FIGURE 3-7  Tight hamstring muscles pull the pelvis backward and create a slumped posture.

Forward lt of trunk

Reduced arm swinging

Rigidity and trembling of head

Rigidity and trembling of extremies

Shuffling gait with short steps

FIGURE 3-8  Forward lean posture seen in Parkinson’s disease.

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The fundamental overarching aim of a postural management programme is to improve and enable an individual’s activities and participation by promoting efficient movement, limiting deformity, reducing pain and facilitating social inclusion. A postural management programme may assist in achieving this aim by (ISPO, 2009; Jones and Gray 2005): • Promoting normal development and patterns of movement by maintaining postural alignment and reducing unhelpful muscle tone and reflexes. • Enhancing postural stabilisation of the trunk as a prerequisite to functional movement and performance of upper limb movements. • Assisting in preventing or delaying the development of deformity or muscle contractures by maintaining postural alignment. • Optimising the position for feeding, respiratory or digestive function. • Enabling and assisting the exploration of the environment. • Improving head control and position, which is essential for orientation, socialisation and communication skills. • Promoting comfort and relaxation and decreasing fatigue. • Managing pressure distribution and reducing the potential for tissue damage to occur.

What Is a Functional Posture? Regardless of ability and impairment, a functional posture will vary greatly not only between individuals, but there will also be a significant degree of internal variation depending on the task that the individual is required to do. A position used for writing, for example, will most likely be different to a position for relaxation and may differ again to a position for feeding. The number of differing activities and postures that we all undertake during the day is almost limitless. This becomes a real problem for individuals with postural control issues who are restricted in their ability to move between positions or may be confined to one specific seat for most of the day. A functional posture is one that not only offers stability and maintains alignment but also enables functional movement wherever possible with energy efficiency to enable sustaining the posture for any length of time. In sitting, it is generally suggested that this is achieved through the stabilising of proximal body parts such as the pelvis, spine and shoulders, as a prerequisite for achieving distal control, e.g., of the head, neck and upper limbs. For example, stability at the pelvis, trunk and shoulder girdle is required for fine motor and hand control. Traditional seating and positioning theories have focused on achieving an upright symmetrical posture with 90 degrees of flexion at the hips, knees and ankles (commonly referred to as the 90,90,90 position). However, while this may be considered a useful base to start from, it is more widely accepted that this position is not always the most functional position for an individual to sustain and that positioning solutions are likely to require a delicate balance (and often compromise) between achieving an upright symmetrical posture and an individual’s ability to function (Pope, 2002).

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In infants and young children, the development of postural control is closely intertwined with the development of movement and consequent motor skill acquisition. It is therefore important to have an understanding of how postural control develops when assessing and determining the optimum postural management equipment. In the past, motor development was regarded as an innate, maturational process; a child would learn to sit when they were ready (Peiper, 1963). However, nowadays it is accepted that experience plays an important role although it is debated as to what extent. Theoretical frameworks for motor development such as dynamic systems theory (Thelen, 1995) and neuronal group selection theory (Hadders-Algra, 2000) propose more complex systems and influences on motor development than genetics alone. Postural management solutions therefore need to be relevant to the child’s developmental stage and carefully consider not only how they will impact and improve the child’s posture, but their present function and future development of function.

Assessment of Postural Ability for Functional Positioning Solutions This section will focus on the assessment of a child’s or adult’s postural ability with the aim of providing functional seating equipment (Fig. 3-9). While seating is a functional posture for many activities during the day, other positions such as standing or lying may also require assessment to promote maximum function. For some individuals, they may use alternative equipment such as a standing frame for certain activities. For example, a child may need to use their augmentative assistive communication equipment effectively when in a standing position. The assessment process for other functional positions should be largely similar and follow this systematic, holistic approach to equipment provision. When a young person or adult is referred for Electronic Assistive Technologies (EAT), what do you need to consider regarding their posture in sitting, standing or lying? It will be helpful to refer back to the ICF framework to ensure that you consider this piece of equipment in terms of how it might benefit or impact on all components of the ICF; their body structure and function, their activity and participation. Consider the environmental or personal factors that may affect the use of this equipment. You will already have asked the ‘bigger picture’ questions around how this equipment will fit into their life, what the purpose of this equipment will be and importantly what the person’s priorities are. For a person to be able to use any equipment effectively, they will need to be positioned optimally for both Gathering your informaon

Idenficaon of problems and needs

Recommendaons for prescripon

Constraints FIGURE 3-9  Assessment process diagram.

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comfort and function. However, there may be many factors which impact either on this optimum positioning or the use of the equipment, which need to be considered. You will need to ascertain not only the important information that will identify the person’s individual problems and their needs, but also identify what constraints there might be to any recommendations you consider.

Gathering Your Information The following information will need to be gathered from the child or adult user’s perspective, from families and caregivers, as well as from other professionals involved in this aspect of their care.

Medical Conditions Affecting Posture • What is the person’s general health like? If a person is often unwell, their tolerance of seating may be reduced. • Is the person in any pain? Pain may be experienced for myriad reasons, impacting on a person’s tolerance to attain a certain posture or to maintain a posture for any length of time. This is therefore one of the most important factors to consider prior to any seating provision. • Has the person had any orthopaedic interventions in the spine, upper or lower limbs or are any planned in the near future? • Does the person experience seizures? How might this affect any seating provision? • Are there any musculoskeletal concerns affecting posture? • Are there any vulnerable pressure areas which may affect skin integrity? • What is the person’s swallowing ability like? This may affect a person’s head and trunk position. • Is there a respiratory condition impacting on positioning? • Are there any nutrition needs? Does the person need to be in an upright position? Does the wheelchair have to accommodate any storage of nutrition equipment? • Are there any continence issues to consider? • Are there any sensory needs? Does the person have any visual and hearing difficulties impacting on their posture? • What is the person’s weight and height? Does this affect their choice of equipment provision? • For night-time positioning equipment, are there any sleep issues?

Psychological Factors Impacting Posture • Are there any behavioural issues which may impact on the optimum posture and safety of the equipment? • Are there any reasons why this equipment may not be acceptable for personal reasons? What are the young person’s, adult’s or family’s/carer’s experiences of equipment in the past which may impact on future provision?   

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Social and Environmental Factors Affecting Posture It may be useful to consider the following factors: • Home and family, carers, respite care, other environments, including school where the seating may be used. • Daily routine in different environments. • How will this equipment be transported? • Eating and drinking – will this equipment be used for this? What other equipment will need to be considered? • How will the person transfer in and out of the equipment? • What personal care is required?    Next is the physical assessment.

Physical Assessment It is useful to have a systematic approach to the physical assessment to assess: • Position of the pelvis. • Direction of lower limbs in relation to pelvis. • Movement and position of hips, knees and feet. • Shoulder rotation and obliquity. • Movement and position of the spine. • Movement and position of the arms. • Position of the head. • Weight distribution and weightbearing.    This will enable you to gain a picture of the person’s preferred posture, their abilities in the position with and without support and any limitations of movement they have. When assessing for seating or standing, it is usually useful first to see how the person is positioned in their current equipment before taking them out to assess their movements and posture in the lying, sitting or standing positions.

Understanding the Position of the Pelvis The pelvis is often referred to as the ‘keystone’ of posture from which the spine, trunk and limbs move. So, what is a ‘normal’ pelvic position? This is commonly described as a neutral pelvis (Fig. 3-10); the alignment of the anterior superior iliac spine (ASIS) and the pubic bone are in line with each other. The pelvis may be positioned either in posterior or anterior tilt.

Sitting With the Pelvis in Posterior Tilt One of the most common postural issues you are likely to encounter is when a person sits with their pelvis posteriorly tilted (Fig. 3-11): on examination, you will find that the ASIS is higher than the posterior superior iliac spine (PSIS). The pelvis is rolling backward and this puts the spine into a C-type posture. The lumbar spine is flexed and there is kyphosis

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FIGURE 3-10  Neutral pelvis. ASIS, anterior superior iliac spine; PSIS, posterior superior iliac spine.

FIGURE 3-11  Posterior pelvic tilt.

of the thoracic spine. The shoulders are usually protracted (rounded shoulders) and there may be increased extension of the neck with consequent ‘chin poke’ position or the head may fall forward. For those with neurological impairments and limitations in motor control, this posture is likely to have functional implications. Head control may be more difficult and swallowing and speech may be affected due to the position of the head and neck. Due to the limited support

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of the trunk and consequent ability to control trunk movements, balance may be affected, as well as the ability to use the upper limbs for function. With the weight of the upper body on the sacral area, there may be concerns regarding undue pressure and skin integrity. There are many reasons why a person may sit in posterior pelvic tilt. Through your assessment you will need to analyse why this might be. Possible reasons may be tight hamstring or hip flexor muscles, low truncal muscle tone making it difficult to hold the spine upright against gravity or abnormal muscle tone contributing to this posture. Alternatively, you may find that a person may be able to sit with a neutral pelvis out of their wheelchair but due to technical reasons to do with the wheelchair, the person is ‘forced’ to adopt this posteriorly tilted position in their wheelchair. For example, the seat may be too deep so that the person is unable to sit with their pelvis at the back of the seat causing this rolling back posture. Other reasons may be that the hip angle is too acute, the backrest too upright for the person or the footplate is too low. The upholstery of an in situ sling may cause the bottom to slip forward. A loose pelvic belt may be a simple cause. All these clinical and technical reasons need to be considered before a possible solution can be found. For the person who tends to adopt this posture despite adaptations to the wheelchair, three points of control are usually required to aid control: posterior to the pelvis and sacrum to block movement posteriorly, a mechanical block under the thighs or in front of the knees to prevent anterior movement and a lap strap to stabilize the pelvis.

Sitting With the Pelvis in Anterior Pelvic Tilt Anterior pelvic tilt is when the ASIS is lower than the PSIS (Fig. 3-12). This causes an increased lumbar lordosis (inward arching of the lower back) and a tendency to shoulder retraction (shoulders pulled backward).

FIGURE 3-12  Anterior pelvic tilt.

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A person may sit in anterior pelvic tilt for a variety of reasons. They may have tight hip flexor, quadriceps or spinal muscles, which bring the pelvis into this position. Alternatively, they may rest in this position due to weak abdominal muscles, being overweight or due to an increased lumbar lordosis. Technical reasons due to the set-up of the wheelchair may be the cause of this posture, e.g., if the seat cushion is too sloped anteriorly, the back rest too vertical or has an excessive lumbar contour. Sitting in anterior pelvic tilt may cause functional difficulties. It may alter the position of the head, affecting eating and drinking, communication, vision or social interactions. It may cause the shoulders to retract impacting on the use of the upper limbs. Balance of the trunk and upper body may be affected due to limited support from the wheelchair. There may be consequences on pressure loading. If the person continues to adopt this posture despite adaptations to the wheelchair, positioning a primary pelvic belt across the ASIS and attaching it to the back of the seat may be helpful. A secondary strap could then be positioned between 45 and 90 degrees to the seat to prevent the pelvic belt from riding up into the abdomen.

Pelvic Obliquity Pelvic obliquity is when one side of the pelvis is higher than the other (Fig. 3-13). As the pelvis is not symmetrical, there will be a compensatory C-shaped curve in the lumbar and thoracic spine. The shoulder on the side of the raised ASIS will be lower than the opposite shoulder. This may be due to asymmetrical muscle strength or tone, asymmetry of bone structure, soft tissue or the presence of a scoliosis. Some technical causes of pelvic obliquity may be that the seat cushion is not solid enough, the wheelchair too wide, arm supports too high or too low or that the person has just not been correctly positioned in their seat. If the pelvic obliquity is correctable, a small wedge or pad under the lower side of the pelvis may help to level the pelvis. However, if the pelvic obliquity is not correctable, building up the seat under the raised side may help to even out the pressure distribution and load bearing. Care needs to be taken not to overcorrect the obliquity.

FIGURE 3-13  Pelvic obliquity.

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Pelvic Rotation Pelvic rotation is when one side of the pelvis is further forward than the other side (Fig. 3-14). Some degree of pelvic rotation is usually found if there is any pelvic obliquity. This may be due to asymmetry of muscle tone, asymmetry of hip abduction, adduction or hip flexion, leg length discrepancy or a subluxed/dislocated hip. Technical causes of this posture include the trunk not being adequately supported, incorrect footrest heights particularly if there is asymmetry of hip flexion or if the person has not been correctly positioned in their wheelchair. A rear hip belt may assist in derotating the pelvis.

Direction of the Lower Limbs in Relation to the Pelvis The lower limbs are normally perpendicular to the ASIS but may be positioned in either hip abduction (Fig. 3-15) or adduction (Fig. 3-16). The hips may be ‘windswept’ to one side (Fig. 3-17).

Movement of the Lower Limbs It is important to know how much range of movement a person has in their joints and muscles to be able to be positioned in a functional, upright position and to be comfortable for a period

FIGURE 3-14  Pelvic rotation.

FIGURE 3-15  Hip abduction: the femurs are away from the midline.

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FIGURE 3-16  Hip adduction on one side: right femur is toward the midline.

FIGURE 3-17  ‘Windswept’ hips: legs toward one side of the body, e.g., left femur is in abduction and right is in adduction.

of time. The main measurements of range of movement in the lower limbs that impact on postural ability are shown in the next paragraph. These measurements need to be accurately carried out with the person lying on a firm plinth. It will require two people, one of whom should be experienced in measuring joint movement. It is important to note how much stretch or pressure is required to achieve a certain range of movement. For example, if the hip can be flexed to 90 degrees but this cannot be tolerated for more than a few seconds, then the person will not be comfortable to sit with their hip in this position for any length of time. Always check asymmetry of movement as this will require accommodation within equipment. Important measurements required for seating include: • Hip flexion (movement of the knee toward the chest). Without sufficient hip flexion, a person is unable to sit with their hips at right angles. • Hip abduction/adduction with hip flexed to 90 degrees (movement of the hip away from the midline/toward the midline). This is often uneven, right to left, and seen with internal rotation of one of the hips. It will affect the position of the pelvis and how the person is taking weight through their buttocks. In children and young people, it can be a sign of changes at the hip joint such as hip subluxation.

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• Hip internal/external rotation with the hip flexed to 90 degrees (rotation movement of the hip toward/away from the midline). This will affect the position of the femurs in relation to the pelvis. • Popliteal angle (measures hamstring muscle length). • Knee flexion/extension with hips flexed to 90 degrees. • Ankle dorsiflexion/plantarflexion with hip flexed to 90 degrees. • Thomas test (measures any fixed flexion deformity at the hip).    SHOULDER ROTATION AND OBLIQUITY This should be assessed in lying when the person is relaxed to see if the shoulders are symmetrical and, if not, whether the posture is fixed or moveable. This can then be observed in sitting to see if it changes, as this will indicate whether the equipment will have to accommodate a fixed posture or whether increased support may enable a more symmetrical position. MOVEMENT AND POSITION OF THE SPINE When the pelvis is in a neutral position, the lumbar spine has a degree of lordosis, the thoracic spine some kyphosis and the cervical spine lordosis (Fig. 3-18). However, there can be abnormal curvature of the spine. A sideways curvature is termed a scoliosis (Fig. 3-19). An abnormal rounding of the back is termed kyphosis. MOVEMENT AND POSITION OF THE UPPER LIMBS Check whether the upper limbs are flexed, extended or rotated. This may affect the position of the upper body.

FIGURE 3-18  Neutral spine.

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FIGURE 3-19  Scoliosis of the spine.

POSITION OF THE HEAD Is the person able to hold their head upright in a midline position? If not, are there any reflexes which may be affecting this, e.g., ATNR? Does the person have altered muscle tone which is affecting their head position? WEIGHT DISTRIBUTION AND LOADBEARING Assess where the person is taking weight through their buttocks. Is it symmetrical or asymmetrical?

Assessment Out of Equipment in the Sitting Position Always sit the person on a plinth or bench with their feet on the floor so that you can assess their posture out of a wheelchair and how much support they require to achieve an upright, functional posture. It may be helpful to ask yourself the following questions: • Where are your hands supporting the person’s body? • What are your hands doing? Are they correcting, providing stability or preventing movement? • How much force are you applying with your hands? • In what direction are your hands applying the support? • How much surface contact is required; a whole hand or less? • What is the least amount of support needed? • Why is this person sitting like this and is there an obvious cause?

Using Measurement Tools Measurement tools are useful in capturing the postural ability of a person in a systematic way. Examples of these are: the Chailey Levels of Ability (Pountney et al., 2004), which can

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be used to determine the child’s postural ability in differing positions; the Oxford Centre for Enablement Management of Physical Disability 24-7 (Pope et al., 2007), which is a comprehensive and systematic postural assessment format, and the Seated Postural Control Measure (Gagnon et al., 2005), which is designed to demonstrate functional outcomes from seating provision.

Case Studies Alan’s Case Study (Adult) Alan is a 79-year-old male with a dense, left-sided hemiplegia following a stroke. He is currently using a self-propelling wheelchair as his main form of mobility but is highly reliant on care staff to assist him. Alan is attempting to move his chair using his right foot and arm, but this is causing him to slide in his seat, causing shoulder pain and he is then requiring assistance to be repositioned. He has also developed an area of redness on his sacrum, which is causing discomfort.

Key Assessment Data MEDICAL Alan has a dense, left-sided hemiplegia following a haemorrhagic stroke due to an arteriovenous malformation. He is able to communicate verbally, although his speech can be slow at times. He has no active movement of his left arm and little use of his left leg. He has a history of pressure areas on his sacrum, which have resulted in periods of bed rest in the past and has left this area of skin highly vulnerable to further pressure damage.

Social/Environmental/Psychological Alan lives in a large residential care setting that is fully adapted and wheelchair accessible. Prior to his stroke he was very fit and active and he is becoming increasingly depressed by his lack of independent mobility and inactivity. Alan has been able to do an assisted standing transfer; however, the height of his wheelchair is very low to enable him to foot propel so this is becoming increasingly difficult.

Physical Key findings of the physical assessment are: • Alan has very limited active movement in his left arm and leg. • Low tone through the left side of his trunk and lower limb with significant spasticity in his left upper limb. • Scoliotic spinal curve convex to the right (this is correctable). • Predominantly sits in posterior pelvic tilt with subsequent kyphotic spinal curvature – he is able to correct this but cannot maintain it in his current seating. • Right shoulder pain due to overuse from self-propelling and also from holding onto the armrest of his chair to prevent him from leaning to the left.  

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Postural Management Goals • To improve his independence and comfort. • To establish a stable functional position to improve his independent mobility and free up his right hand for functional activity. • To increase seating tolerance by preventing sliding in the seat and therefore enable increased participation in activities. • To prevent reoccurrence of pressure areas on his sacrum through improved pressure distribution and reduction in shearing damage due to sliding. • To reduce shoulder pain in his right shoulder.

Identified Seating Requirements It is identified that Alan’s seating needs to: • Secure his pelvis to prevent sliding and falling into posterior tilt. • Offer firm back support particularly to the posterior aspect of his pelvis; support required up to shoulder height. • Support around the lateral aspects of pelvis to maintain pelvic alignment and assist with trunk alignment. • Offer lateral support to his trunk to correct scoliosis. • Have a simple head support for rest periods • Offer support for his left hemiplegic arm. • Be of an appropriate height to facilitate standing transfers.

Recommendations • Liaise with medical team regarding pain management for his right shoulder. • Liaise with nurses regarding monitoring of pressure areas. • A two-part customised seating system is recommended; a seat cushion that provides firm postural support with an ischial ramp and pressure relief, and a firm padded back support with thoracic lateral supports, head rest, padded pelvic belt and arm support. • Assessment in a powered wheelchair with right-hand joystick control and possible seat riser to assist with transfers.

John’s Case Study (Paediatric) John is a 10-year-old boy who has a diagnosis of dyskinetic/dystonic cerebral palsy with four-limb involvement. His parents report that he is not really tolerating his current seating system, which is an off-the-shelf seating system with dynamic backrest, and appears to be experiencing a lot of discomfort in his chair. His teaching assistant in school reports that he is spending a lot of the day in school out of the chair due to distress in his seating. This is impacting negatively on his participation in educational activities and also on his social interactions. His parents and teaching staff feel that he has the cognitive potential to access electronic assistive technologies, but this has not been possible as he is spending too little time in his seat and a consistent access method has been difficult to ascertain.

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Assessment Findings MEDICAL John has dyskinetic (dystonic) cerebral palsy Gross Motor Function Classification System Level V (Palisano et al., 1997), and presents with very strong extensor patterning of his limbs and rotation of his head and neck. When he is relaxed, John has low central muscle tone (e.g., in his trunk, neck and pelvis) and high distal tone (e.g., upper and lower limbs). He is on a high level of medication to manage his dystonia. John receives all his nutrition through a gastrostomy tube and has a high level of seizure activity.

Social/Environmental/Psychological John lives at home with his parents and younger sibling. He attends a school for children with complex special needs as a day pupil. Their home has been fully adapted and is wheelchair accessible. John is a very sociable young boy who loves interaction with his sibling and peers and is showing some potential for higher-level communication; he currently uses eye blinking as his communication method.

Physical Key findings of the physical assessment are: • Very strong dystonic patterning. • Strong extensor tone with adduction of his lower limbs. • Lateral spinal curve convex to the right (this is still correctable). • ATNR evident at times. • Able to be placed in seated position when relaxed, but unable to maintain this without support. • In sitting, his pelvis is oblique raised on the left but this is not evident in lying. • Loss of hip flexion in the left hip, only able to achieve 80 degrees of flexion.

The following postural management goals were identified for John: • To improve comfort and reduce pain. • To increase seating tolerance and therefore enable increased participation in activities and education. • To facilitate a stable functional position to enable assessment for electronic assistive technology access.

Identified Seating Requirements It is identified that John’s seating needs to: • Accommodate his reduced hip flexion on the left side as this then reduces his pelvic obliquity. • Maintain maximum flexion on the right to anchor position and to inhibit extensor pattern. • Maintain his hips in an abducted position to assist in inhibiting his extensor patterning.

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• Accommodate his fixed anterior pelvic tilt. • Provide support to the lateral aspects of his pelvis to maintain pelvic alignment and assist with trunk alignment. • Provide lower lateral support at the apex of his lateral trunk curvature and high on the left thoracic to correct his scoliosis. • Provide improved head control – particularly if eye gaze technology is to be explored. • Maintain a dynamic element within the seat, as it is felt this is assisting with tolerance.

Recommendations • To liaise with his medical team regarding muscle tone management. • To provide a custom-made foam seat moulded to accommodate John’s fixed postural deformities, fitted into a seating system with a dynamic backrest. • To assess for alternative head supports that have an option to add anterior and lateral support.   

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Ham, R., Aldersea, P., Porter, D., 1998. Wheelchair Users and Postural Seating: A Clinical Approach. Churchill Livingstone, London. Hansson, E.E., Beckman, A., Håkansson, A., 2010. Effect of vision, proprioception, and the position of the vestibular organ on postural sway. Acta Oto-Laryngologica 130 (12), 1358–1363. Horak, F.B., Macpherson, J.M., 2011. Postural orientation and equilibrium. In: Terjung, R. (Ed.), Comprehensive Physiology. Huang, I.C., Sugden, D., Beveridge, S., 2009. Assistive devices and cerebral palsy: factors influencing the use of assistive devices at school by children with cerebral palsy. Child: Care, Health and Development 35 (5), 698–708. Ibuki, A., Bernhardt, J., 2007. What is spasticity? The discussion continues. International Journal of Therapy and Rehabilitation 14 (9), 391–395. ISPO, 2009. Recent Developments in Healthcare for Cerebral Palsy: Implications and Opportunities for Orthotics. International Society of Prosthetics and Orthotics, Denmark. Jones, M., Gray, S., 2005. Assistive technology: positioning and mobility. In: Effgen, S.K. (Ed.), Meeting the Physical Therapy Needs of Children. FA Davis Company, Philadelphia. Lance, J., 1990. What is Spasticity? Lancet 335, 606. Latash, M., Hadders-Algra, M., 2008. What is posture and how is it controlled? In: Hadders-Algra, M., Carlberg, E.B. (Eds.), Postural Control: A Key Issue in Developmental Disorders. Mac Keith Press, London. Latash, M., 2008. Neurophysiological Basis of Movement, second ed. Human Kinetics, Illinois. Massion, J., Alexandrov, A., Frolov, A., 2004. Why and how are posture and movement coordinated? Progress in Brain Research 143, 13–27. NICE, 2012. Spasticity in Children and Young People, CG 145. National Institute for Health and Care Excellence, London. Palisano, R., Rosenbaum, P., Walter, S., Russell, D., Wood, E., Galuppi, B., 1997. Development and reliability of a system to classify gross motor function in children with cerebral palsy. Developmental Medicine and Child Neurology 39, 214–223. Peiper, A., 1963. Cerebral Function in Infancy and Childhood. Springer, Michigan. Pope, P.M., 2002. Posture management and special seating. In: Edward, S. (Ed.), Neurological Physiotherapy. Churchill Livingstone, Edinburgh. Pope, P.M., 2007. Severe and Complex Neurological Disability: Management of the Physical Condition. Elsevier Butterworth-Heinemann, Oxford. Pope, P.M., Murphy, W.M., Postill, P., Long, D., 2007. Management of Physical Disability 24-7 (MPD 24-7). Oxford Centre for Enablement, Nuffield Orthopaedic Centre NHS Trust. Pountney, T.E., Mandy, A., Green, E.M., Gard, P., 2002. Management of hip dislocation with postural management. Child: Care, Health and Development 28 (2), 179–185. Pountney, T., Mulcahy, C., Clarke, S., Green, E., 2004. The Chailey Approach to Postural Management: an explanation of the theoretical aspects of postural management and their practical application through treatment and equipment, second ed. Chailey Heritage Clinical Services, North Chailey. Pountney, T.E., Mulcahy, C.M., Clarke, S., Green, E.M., 2000. The Chailey Approach to Postural Management: An explanation of the theoretical aspects of postural management and their practical application through treatment and equipment. Active Design, Birmingham. Other sensory feedback that affects motor performance. In: Purves, D., Augustine, G.J., Fitzpatrick, D., Hall, W.C., LaMantia, A., McNamara, J.O., Williams, S.M. (Eds.), 2004. Neuroscience, third ed. Sinauer Associates, Sunderland, MA. Reilly, D.S., Van Donkelaar, P., Saavedra, S., Woollacott, M.H., 2008. Interaction between the development of postural control and the executive function of attention. Journal of Motor Behavior 40 (2), 90–102.

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Saladin, K.S., 2011. Anatomy & Physiology: The Unity of Form and Function. McGraw-Hill, New York. Sanger, T.D., Chen, D., Fehlings, D.L., et al., 2010. Definition and classification of hyperkinetic movements in childhood. Movement Disorders 25, 1538F49. Shumway-Cook, A., Woollacott, M., 2001. Motor Control Theory and Practical Applications, second ed. Lippincott, Williams and Wilkins, Philadelphia. Thelen, E., 1995. Motor development. A new synthesis. American Psychologist 50 (2), 79–95. WHO, 2001. International Classification of Functioning, Disability and Health. Switzerland, World Health Organisation, Geneva. WHO, 2007. International Classification of Functioning, Disability, and Health: Children and Youth Version: ICF-CY. Switzerland, World Health Organisation, Geneva.