With weakness and compensation there may be no way to eliminate a compensatory pattern of movement without eliminating the function it serves, but it is important to try to find compensations that pose less of a risk of contracture and deformity and to try to avoid development of the contractures that contribute to the self-perpetuating evolution of weakness/contracture/functional loss [6, 14, 30, 31, 35]. The effects of chronic positioning, the unopposed influence of gravity, and imbalanced muscle activity around joints contribute to the development of hypoextensibility (tightness) and contracture [2, 6, 11, 30, 35, 119]. Positioning for function and for management of the musculoskeletal system should be offered [6, 21, 23, 120–122].

Stretching: Prevention/minimization of contracture requires sufficient daily elongation of musculature and daily movement through more complete ranges of motion than the individual with MD typically uses actively and independently [1, 2, 6, 11, 21, 36, 44, 45, 119, 123]; these may be achieved through preventative stretching and varied positioning, facilitation of movement and position changes, use of therapeutic interventions including passive and active elongation, daily range of motion/stretching, the appropriate use of orthotic intervention, splinting, serial casting, power positioning components on mobility devices, participation in aquatics and cycling/assisted cycling and other forms of submaximal active movement and participation, and the use of adaptive equipment for positioning and prolonged passive elongation including the use of standers and stand-and-drive mobility devices [5, 6, 11, 19, 21, 23, 24, 37, 44, 45, 55, 119, 123–127]. A stretching program should begin early in the course of the disease and is more effective and more easily established as part of the daily routine if it is begun before muscle tightness/contracture is established and before stretching is uncomfortable. A preventative stretching program should address structures known to be at risk for tightness based on natural history of the specific diagnosis, as well as any structures identified by individual assessment to be at risk for contracture [6]. Direct and skilled physical therapy techniques of muscle elongation, joint mobilization, gentle manual traction, and use of modalities and other manual therapy techniques to increase joint mobility and muscle elongation should be included as appropriate for individual patients based on recommendations after individual physical therapy evaluation [128] (Table 8.3).

Orthotic intervention/adaptive equipment: Orthotic intervention may be recommended for function and/or for assistance in management of the musculoskeletal system and may include consideration of many different choices, configurations, and materials, for upper and lower extremities, trunk, and neck. Lower extremity orthotic intervention may include consideration of ankle–foot orthoses (AFOs or “short leg orthoses”), knee–ankle–foot orthoses (KAFOs or “long leg braces”), knee extension splints, inframalleolar orthoses (“foot orthoses”), or other types and configurations of orthoses, with control of varying degrees of freedom depending on specific diagnosis and individual assessment [6, 21, 23, 123, 129]. Upper extremity splinting, orthotic intervention, and support may include splinting for stretching or support of function [130] and is increasingly including exploration of exoskeletons and robotics to increase functional use of hands in the presence of proximal weakness [131, 132].

Use of lower extremity orthotic intervention and adaptive equipment for function during walking typically depends upon the distribution of weakness and the required use of compensatory patterns of movement for function. In the presence of relatively greater proximal weakness in individuals who are independently ambulatory, such as in Duchenne muscular dystrophy (DMD), the use of AFOs during walking is not typically recommended. This is because AFOs tend to compromise ambulation by limiting the use of compensations needed for walking, such as toe-walking or intermittent toe-walking, may compromise proximal compensations needed to keep the line of gravity behind the hip and in front of the knee to maintain ambulation, and may make it more difficult to get up from the floor, with the added weight of AFOs further compromising function [6, 129]. In other types of MD characterized by relatively greater distal than proximal weakness, or in which more global weakness is present, such as in some types of congenital myopathy, AFOs may assist in providing distal stability. This can be beneficial during standing and/or ambulation as long as AFOs are lightweight enough and offer optimal support without unnecessarily compromising function or movement that is necessary for function. Newer, ultra-lightweight carbon fiber AFOs used in conjunction with lower profile orthotic intervention at the foot and ankle may offer lightweight support without compromising function in those with greater distal than proximal weakness. This can potentially offer dorsiflexion assist during swing to prevent “foot drop” and “steppage gait” and potentially provide some floor-reaction support of knee extension during stance and may decrease fatigue. Ankle height or supramalleolar orthoses (SMOs) are not typically helpful because they add weight that challenges active dorsiflexion (typically weak in MDs) without adding dorsiflexion assist. However, these could be considered in the rare situation in which weakness is extremely mild, with good strength in anterior tibialis, but with poor medial–lateral alignment that requires more support than an inframalleolar orthosis. KAFOs may be useful in children with greater weakness throughout lower extremities in the absence of the ability to support weight-bearing independently. This approach has been shown to extend walking for several years in some individuals with DMD when independent walking becomes too difficult because of inability to support weight through lower extremities without support and/or inability to maintain biomechanical positioning to mechanically lock joints in support of weight-bearing and ambulation [46, 55, 121, 133–136]. Braced ambulation with KAFOs may be therapeutic rather than functional across settings [46] and is most often used in combination with motorized mobility for functional, safe, independent mobility in settings in which braced ambulation is not functional or does not allow optimal participation.

Use of lower extremity orthotic intervention and adaptive equipment for musculoskeletal management (to prevent contracture and deformity) may include the use of AFOs [6, 21, 123], KAFOs [23, 55, 133], thigh binders, splints, serial casting [126, 127], or other positioning devices at night [21] or in the evening or during any portions of the day when they will not unduly interfere with function [6]. The use of AFOs at night has been shown to minimize the progression of plantarflexion contractures [21] and is recommended if tolerated. AFOs used at night need to be comfortable and should be custom molded and lightweight enough not to unduly restrict bed mobility. A bed or foot tent can hold the blanket up off of the feet to avoid the feet getting tangled in the sheets. Adjustable angle orthoses can sometimes be used to provide differing amounts of stretch at different times of the day, or gradually increasing elongation for comfort. The use of ankle height or SMOs may be helpful for those using a wheelchair full time, in order to assist in maintaining optimal medial–lateral alignment if the footplate of the chair can be successfully used to limit excessive plantarflexion. The number of hours per day that a muscle is in a lengthened vs. shortened position will influence the development or prevention of contracture. Standard recommendations for prevention of progressive contracture support the maintenance of a lengthened position for six of every 24 h [137]. The use of standers and stand-and-drive motorized mobility devices is recommended for providing prolonged passive elongation into simultaneous hip and knee extension in an upright weight-bearing for optimizing and maintaining joint range of motion, providing muscle elongation over multiple joints, and optimizing bone integrity, if tolerated [20, 55, 133, 134, 138, 139].

Prevention/minimization of spinal deformity typically involves: promotion of symmetry through the vertebral column and pelvis; support of appropriate amounts of extension and flexion at specific levels of the vertebral column; maintenance of flexibility; support of optimal posture; and minimization of the asymmetrical deforming forces of compensatory patterns of movements used for function (in most neuromuscular disorders) or intrinsic to diagnosis (such as in FSH). The progression of spinal deformity in neuromuscular disorders has been well studied, and understanding of the individual pathokinesiology in each diagnosis and detailed assessment and management of the interaction between components in each individual are critical. The development and progression of scoliosis has been most extensively studied in DMD, which can be used as a model to understand the pathokinesiology, and can inform conservative treatment. The natural history of scoliosis is changing with the use of steroids in DMD, with scoliosis appearing later, and with less devastating progression [140].

Scoliosis in ambulatory individuals with DMD has been studied [141, 142] and is characterized by a flexible, functional scoliosis related to asymmetrical lower extremity position/contracture, pelvic obliquity, asymmetrical realignment of shoulders, head, and upper extremities [35, 143, 144]. Fixed spinal asymmetry is typically minimized spontaneously in ambulatory individuals by prolonged, protective spinal hyperextension and locking of posterior intervertebral facet joints at lumbar and lumbosacral levels, and alternating torso shift and lateral trunk elongation [11, 35, 145].

Historically, prolongation of ambulation by management of lower extremity contracture and the use of long leg braces appeared to slow the development of scoliosis in some [146], likely via prolongation of protective spinal hyperextension maybe through the adolescent growth spurt, and continued torso shift and lateral trunk elongation over symmetrical lower extremities [35, 145, 147, 148]. Factors that have appeared to influence whether or not scoliosis appears prior to final loss of ambulation included: the age at which walking ceases; intervention used or not used to prolong ambulation; and final gait pattern [146].

It has generally been agreed that spinal curves during the ambulatory period are not usually “fixed” (i.e., rigid or inflexible), are functionally necessary for ambulation, and cannot be corrected without risking the loss of ambulation [35]. Attempts should be made, therefore, to minimize long-term effects of asymmetry with stretching, positioning, etc., while allowing compensations necessary for function. In individuals with intrinsic asymmetry of weakness, as has been identified in FSH, and extreme anterior pelvic tilt and lumbar lordosis, the use of a soft corset during ambulation may provide support that decreases pain and fatigue during ambulation without compromising compensations to the extent that ambulation is compromised.

Scoliosis in non-ambulatory individuals: Scoliosis as a significant problem in DMD and other neuromuscular disorders typically either begins or develops more rapidly as ambulation is lost and full time use of a wheelchair begins [35, 149]. It is one of the most serious and disabling complications of many neuromuscular disorders and has been studied extensively in DMD, with the understanding of the principles of progression and treatment gained in DMD useful in the management of all neuromuscular scoliosis [150]. Neuromuscular scoliosis can progress to a level of incapacitating severity that compromises pulmonary function, sitting ability, upper extremity function, comfort, and cosmetic integrity [11, 35]. The progression of scoliosis is variable, however, and final deformity ranges from mild in some individuals to severe in others [150]. The significance of the variability is in the opportunity it offers for effecting change and for making use of intervention that may prevent or minimize the development of scoliosis. Attempts at successful management must be based on a comprehensive understanding of the factors that contribute to the development of scoliosis. Aggressive conservative management must be coordinated with consideration of surgical options in order to prevent the catastrophic progression to severe deformity in all individuals with MDs.

Factors that contribute to the development of scoliosis can be divided into those factors that make the spine vulnerable and those factors that initiate asymmetry [151].

Asymmetrical forces imposed on the symmetrically weak and vulnerable spine [151]:

The deforming force of gravity on the vertebral column increases in the presence of asymmetrical spinal-pelvic alignment that compromises the simple mechanical ability of the vertebral column to withstand the force of gravity. In addition, the resultant unequal distribution of weight on epiphyseal growth plates increases the potential for an initial flexible scoliosis to become structural.

Management of the spine must be anticipatory and preventative with consideration across the continuum of intervention options, including stretching, positioning, external support, and surgical options, with coordination between the multidisciplinary team. The use and timing of anticipatory and preventative conservative measures is coordinated with ongoing assessment regarding the potential need for surgical stabilization to manage curves that progress in spite of conservative measures. Care must be taken to coordinate with the rest of the team, with particular coordination between PT, orthopedics, pulmonary medicine, and cardiology, as conservative measures are employed. This helps ensure that the window of opportunity for surgical spinal stabilization (which is dependent on the interaction between pulmonary, respiratory, and cardiology status) is not missed, if the individual will need surgical stabilization at some point (see Chapter 9).

Intervention described in the literature has included prolongation of ambulation, external support including bracing, specialized seating systems, wheelchair modifications, promotion of upper extremity symmetry, control of lower extremity position, and spinal surgery. Bracing of the spine in individuals with DMD has historically not been tolerated or successful but may have a role in other diagnoses and situations, especially in younger children with myopathies characterized by more profound trunk weakness at earlier ages. Orthotic intervention may include supportive garments, corsets, or spine jackets in younger children with some types of MD in order to support more vertical, symmetrical, and extended spinal alignment and more stable posture and stability in upright. Such interventions may assist in maintaining spinal symmetry, or providing some support which may be beneficial in ambulatory individuals in whom some support is helpful but must avoid excessive restriction of movement that may limit compensatory movement required for ambulation [158–160].

Optimal support and positioning in seating systems is critical in musculoskeletal management of the spine and extremities and must include maintenance of midline, symmetrical pelvic position with prevention of lateral pelvic tilt, horizontal pelvic rotation, and excessive anterior or posterior pelvic tilt; maintenance of a midline erect spine, and support of a symmetrical midline head position. Typical recommendations include: a solid seat and back; rigid lateral trunk supports; hip guides; adductors; a head rest and adequate upper extremity and foot and leg support; with power positioning components for power tilt, power recline, separately elevating power elevating leg rests, power adjustable seat height, and power standing [6]. Seating system components are needed for support for function, prevention of progressive contracture and deformity, and maintenance of skin integrity. Power positioning components are needed for function, for independent position change for prevention of contracture and deformity, for support of adequate frequency and duration of weight-bearing throughout the day, and for provision of independent weight shift and pressure relief throughout the day that is adequate to maintain skin integrity.

Physical therapy management of the spine in the individual with MD must involve ongoing evaluation and intervention. Ongoing evaluation must attend to the asymmetrical forces acting on the vulnerable spine and should include assessment of: