INTRODUCTION AND PURPOSE
Children who ambulate less than 2 hours per day or are nonambulatory often experience painful and costly complications because of extended periods spent in seated, supine, and prone postures.1 Supported standing programs have been used in various settings for more than 50 years in an effort to reduce and prevent complications and to optimize various aspects of function.2 In spite of widespread clinical use, we lack evidence-based recommendations for effective program dosing.
In a systematic review of the pediatric- and adult-supported standing program literature,3 the available evidence provided moderate support for a beneficial effect on bone mineral density (BMD) of the legs and spine; range of motion (ROM) of the hip, knee, and ankle; spasticity of the ankle; and bowel function. Therapists and individuals who used standers reported benefits from supported standing programs on weight-bearing, pressure relief, ROM, and psychological well-being. Findings were inconclusive for a positive effect on cardiopulmonary and bladder function, muscle strength, and alertness.
This article extends our initial systematic review3 by using the literature to make specific clinical dosing recommendations for supported standing programs for children. In the absence of pediatric-specific evidence, the authors offer other considerations on the basis of expert opinion. The intent of this approach is to provide suggestions for clinicians to use in designing and implementing optimal evidence-based supported standing programs, but always in the context of professional clinical judgment and client/caregiver goals and preferences.
As Figure 1 illustrates, we identified peer-reviewed literature and published abstracts from conference proceedings through multiple search engines (MEDLINE, CINAHL, GoogleScholar, HighWire Press, PEDro, Cochrane Library databases, and the American Physical Therapy Association's Hooked on Evidence) from January 1954 to August 2012. We included the earliest date to give an historical perspective, although the 1954 study was eliminated because it was adult specific. Search terms were “stander,” “standing,” “standing shell,” “tilt table,” “standing frame,” “whole body vibration (WBV),” and “children,” or “cerebral palsy (CP).” Preliminary inclusion criteria were (1) English language, (2) published in a peer-reviewed journal or official conference proceedings, and (3) included participants, birth through 21 years with atypical development, with or without a neuromuscular diagnosis, including CP. Overall, we identified 687 studies, and 87 met the preliminary inclusion criteria. Secondary inclusion criteria were as follows: (1) described a standing frame or similar device and (2) measured quantifiable outcomes. Thirty of the 87 studies met these criteria (see Figure 1). Sources that did not meet the secondary criteria were potential considerations in the authors’ opinion-based comments.
We used the Oxford Centre for Evidence-Based Medicine (CEBM) Levels of Evidence (http://www.cebm.net/?o=1116) and the American Academy of Neurology (AAN) Levels of Evidence (http://www.neurology.org/site/misc/TableClassificationScheme.pdf) to evaluate the strength of the evidence as a basis for clinical recommendations. The CEBM and AAN evidence levels range from 1 to 5: level 1 is the highest level (systematic review of randomized controlled trials); level 5 is the lowest level (expert opinion without critical appraisal). The AAN levels include specific recommendations using clinically interpretable language. The CEBM levels are comprehensive but the CEBM did not offer specific advice on research using survey methodology. Many times, the literature did not provide sufficient information or did not fit clearly into one of the categories. For this reason, we made our best interpretation of the evidence levels for those articles that did not clearly fit the AAN or CEBM guidelines (see Tables 1 and 2). We further rated the evidence with a clinical relevance level system of red light (no evidence; stop), yellow light (minimal evidence; proceed with caution), and green light (moderate or strong evidence; go).
The World Health Organization's International Classification of Functioning, Disability, and Health, Child and Youth Version (ICF-CY) model (http://apps.who.int/classifications/icfbrowser/) was used as the categorizing framework because of its adoption by the World Health Organization as the international standard to describe and measure health and disability. The American Physical Therapy Association has endorsed the use of this model, and it is particularly helpful to describe body structure and function, activity, and participation. Arranging the dosage information by ICF category, we intended to guide clinicians to the currently accepted vernacular.
The systematic review results (evidence) and clinical dosing recommendations have been organized and reported using the following 3 ICF categories and selected subcategories: (1) body functions (b)—mental functions (b110 to b139), functions of the cardiovascular (b410 to b429) and respiratory systems (b440 to b449), functions of the digestive systems (b510 to b539), urinary functions (b610 to b639), and neuromusculoskeletal and movement-related functions (b710 to b789); (2) body structures (s)—structure of the bone as related to BMD (s7400, s75000, s75010, s75020, s76001 to b76004), structure of the bone as related to hip stability (s75001), and skin and related structures (s8103 to s8105); and (3) activities and participation (d)—mobility (d410 to d489) and major life areas (d810 to d859).
Mental Functions (ICF b110 to b139)
Evidence (levels 4 and 5). Three studies4–6 examined the effect of standing on mental function. Gudjonsdottir and Stemmons Mercer5 used the Carolina Record of Individual Behavior to measure alertness in 4 children with CP while using a traditional stander and an experimental stander that rocked side to side. No change was noted between these 2 conditions, but the author stated there was a slight trend toward being more alert when standing in the stander that rocked side to side. On the basis of a survey,4 approximately 90% of school-based physical therapists reported improved self-esteem as a very important or important benefit of a standing program. Psychological tests administered to preschool-aged children with CP using an array of adaptive devices, including prone standers, scored significantly higher in the adaptive equipment than when floor sitting or in a nonadapted chair.6 These results are summarized in Table 3.
Clinical recommendation from the evidence. A minimum of 30 minutes of standing per day may be associated with an alert state and possibly improved academic performance.5,6
Other considerations (authors’ opinions). Consider using a self-propelled, powered stander or standing wheelchair to promote eye-to-eye peer interactions. In the future, electroencephalography or functional near-infrared spectroscopy could be explored as a measure of the effect of standing on alertness.
Functions of the Cardiovascular (ICF b410 to b429) and Respiratory System (ICF b440 to b449)
Evidence. There were no reportable pediatric studies.
Clinical considerations (authors’ opinions). Standing programs must be progressed in a systematic manner with careful monitoring. Initial bouts should start at 5 to 10 minutes at 45° (more or less, as appropriate) and progressed to tolerance. If an interruption in service or schedule change occurs for as little as 3 to 8 days, regress the program with a shorter bout and at a lower angle with therapist judgment and careful monitoring.7 Children who are medically fragile may have reduced lower extremity circulation. For the child who is just beginning a standing program or returns to standing after an interruption, monitoring blood pressure, heart rate, respiratory rate, and oxygen saturation is critical both initially and throughout the standing period (10- to 15-minute frequency).7 Use pressure garments (eg, abdominal binder and support stockings), electrical stimulation for leg muscles, passive/assisted/active stepping or cycling, and/or WBV8 to ameliorate autonomic dysreflexia, baroreflex, syncope, nausea, or dizziness, unless otherwise contraindicated.3,8–10 Forty minutes of standing, 3 to 4 times per week, may reduce leg and foot swelling and decrease breathing difficulties and dizziness.11 Repeated and progressive standing may improve functional circulation.12 Cease standing activity if vital signs become unstable, for example, if oxygen saturation levels fall below 90%.13
Functions of the Digestive System (ICF b510 to b539)
Evidence (levels 4 and 5). Evidence was poor that standing device usage improved bowel function in children. On the basis of survey data from physical therapists working with school-aged children, 34% thought standing was “very important” for bowel and bladder function, whereas 50% thought it was “important.”4 A decrease in gastroesophageal reflux was noted in infants placed on a prone board at a 30° incline from vertical.14 These results are summarized in Table 4.
Clinical recommendation from the evidence. Prone positioning may be a useful part of a reflux management program. As a caution, avoid rigid materials that could create excessive abdominal pressure.14
Clinical considerations (authors’ opinions). Daily standing for 30 to 60 minutes may decrease the use of suppositories and time spent for bowel care.11,15–17
Urinary System (ICF b610 to b639)
Evidence. No reportable pediatric studies and no clinical recommendations for dosing were found.
Neuromusculoskeletal and Movement-Related Functions (ICF b710 to b789)
Evidence (levels 2 and 5). The strongest evidence was for the positive effects of a standing program on hamstring ROM.18 Standing maintained or increased ROM and even prevented knee flexion contractures.19 When standing ceased, knee ROM decreased.18 Standing also increased static and dynamic range of motion for plantar flexors.20 Standing for children as young as 14 months resulted in improved hip ROM.21 These results are summarized in Table 5.
Clinical recommendations from the evidence. Stand at least 45 to 60 minutes daily; 60 minutes is optimal to increase hip, knee, and ankle ROM.18–20 Sixty degrees of total bilateral hip abduction improves abduction ROM, but an optimal angle has not been established.19
Other considerations (authors’ opinions). Greater than or equal to 30° of total bilateral hip abduction may not be feasible initially because of discomfort. Introduce small increments of hip abduction in standing over time to tolerance. Use a knee support and footplate system that allows appropriate poisoning of the feet to ensure biomechanical alignment at the knee, ankle, and foot (see Figure 2). Standing programs can be safely started as early as 9 to 10 months of age.19,21,24,25 Standers that allow for hip extension (beyond neutral) may help combat hip flexor tightness, especially for children with muscular dystrophy, spina bifida, or spinal cord injury22,23 (see Figure 3). To enhance passive stretch of the plantar flexors, add a 15° dorsiflexion wedge, with the subtalar neutral position maintained.26 For tight hamstrings, knee immobilizers may help distribute pressure areas and assist in improving knee extension. For knee flexion contractures, use available devices, such as a contracture bracket (see Figure 4). Avoid direct pressure on the patella and tibial tubercle. Sling-style seat standers may accommodate moderate to severe spine and hip contractures or deformities.
Muscle Power Functions (ICF b730)
Evidence at levels 3 to 5. One researcher27 found increased electromyographic activity and postural responses in a child with spina bifida while in an orthotic standing shell. The majority of the studies in this category combined supported standing with WBV.28–30 All studies except one used a platform that rocked side to side and vibrated. These results are summarized in Table 6.
Clinical recommendation from the evidence. Incorporate WBV, including rocking from side to side and vibration with standing for 10 minutes, twice per day, to increase muscle strength.28,30
Other considerations (authors’ opinions). Adults with CP showed an improvement in Gross Motor Function Measure (dimensions D and E) and isokinetic muscle strength following a combined standing and WBV program when compared with exercise alone.32 Standing in a device that allows for lower extremity movement (flexion and extension) may improve strength.16 Use of a self-propelled stander may promote upper extremity and trunk strengthening.
Muscle tone Functions (ICF b735)
Evidence (level 2). Two level 2 studies20,33 used traditional standing frames and showed a decrease in lower extremity spasticity or tone. Children with CP showed a decrease in triceps surae and tibialis anterior spasticity after 30 minutes of stretch in a supported stander. The decrease in spasticity lasted 35 minutes after cessation of the stretch/standing.33 Salem et al20 showed statistically significant improvements in gait and decreased tone of the soleus following 45 minutes of daily sessions in a stander. These results are summarized in Table 7.
Clinical recommendations from the evidence. Stand for 30 to 45 minutes per day to decrease spasticity.20,33
Other consideration (authors’ opinions). The effect on spasticity may last only for 35 minutes; therefore, follow standing with an activity that may improve with this short duration of decreased spasticity, such as dressing or walking.33
Structures of the Bone Related to Hip Stability (ICF s75001)
Evidence at levels 2 to 5. In 1 study19 and 1 abstract21 authors noted participants standing in 55° to 70° of total bilateral hip abduction had improved acetabular and hip migration indices. Dalén et al34 suggested that standing in neutral hip abduction in a Swedish Standing Shell might have had the opposite effect and actually increased hip subluxation. Two research groups24,25 noted that standing, when combined with other interventions, improved hip biomechanics.
No evidence indicated that supported standing would be contraindicated if the participants had 1 or both subluxed or dislocated hips.25,35 In 1 case, a trochanteric girdle was used to prevent acute bilateral hip subluxation during supported standing.36 Supported standing, as 1 part of a comprehensive hip management program, was shown to possibly prevent repeated need for hip surgery.24 These study authors also agreed that hip deformity, dislocation, and subluxation could only be prevented or reduced if the children with CP were positioned properly in their wheelchairs, standers, and sleep systems throughout the 24-hour period. Hägglund et al24 also recommended frequent, twice per year, and vigilant monitoring of hips with immediate surgical or pharmaceutical intervention as needed. These results are summarized in Table 8.
Clinical recommendation from the evidence. Standing daily for 60 minutes in 60° of total bilateral hip abduction may improve hip biomechanics.19
Other considerations (authors’ opinions). In all equipment, gently try to maximally straighten hips (to neutral, with no flexion) and knees (without hyperextension) and fully load the femur and tibia. Sit-to-stand devices that do not allow a fully upright position (hip and knee extension without pressure on the knees or shins) may be less effective in fully loading the legs and hips.37,38 A force plate or scale may be mounted to some foot platforms to monitor weight-bearing. The caregiver should not be able to move the feet/shoes after achieving upright standing. Consider 30° to 60° of total bilateral hip abduction, based on tolerance, to improve hip biomechanics, although the optimal amount of abduction has not been established.21,24,25 If the participant has had a previous pathological fracture, use extreme caution during the loading and unloading to and from the standing device. Following a fracture or surgical procedure (including muscle and/or tendon lengthening), obtain medical clearance before using a standing device.39 Children with moderate to severe gross motor delays, greater than 25%, should begin a supported standing program at about 9 to 10 months of age, adjusted for prematurity as appropriate. This is based on our knowledge that children who are typically developing begin pulling to stand on their own between 8 and 12 months of age. Discontinue standing if pain occurs, especially concurrent with skeletal deformity, as this could indicate a dislocated hip and warrants medical attention. Adjust all equipment at least every 6 months.24
Skin and Related Structures (ICF b8103 to b8105)
Evidence at level 4. Pressure relief from sitting was the highest perceived benefit, and many therapists (58.7%) rated it as very important.4 For children with conditions that result in compromised motor and sensory function, pressure relief may be a reasonable goal for a standing program (see Table 9). However, no evidence that standing positively affected skin integrity in children and no clinical recommendations for dosing were found.
Other considerations (authors’ opinions). Ensure that transfers and sit-to-stand mechanisms (if used) do not produce shear forces on the spine and sacrum. A sit-to-stand device with a seat that pivots/rotates or a standing wheelchair stander might be ideal to decrease shear forces during transfers, as described (but not measured) by Sprigle and colleagues40 (see Figure 5). A stander that uses a hydraulic lift mechanism with a sling style seat may be the best choice. Make sure that the user's buttock area and undergarments are clean and dry. Choose fabrics that keep the skin cool and moisture free.40 The administrator of the standing program should inspect skin areas of concern for pressure points (typically, ischial tuberosity and sacrum). Use frequent, short bouts of supported standing and/or incorporate weight shifts to avoid skin breakdown due to prolonged pressure. This is especially important to consider in the school setting when a student may be placed in the standing position for the class period.
Body Structure of the Bone as Related to BMD (ICF s7400, s75000, s75010, s75020, and s76001 to s76004)
Evidence at levels 2 to 5. These results are summarized in Table 10. Several researchers reported evidence for various bony sites; however, the amount of weight-bearing through the tibia and femur was neither measured nor controlled. In addition, the amount of time spent standing in many studies, less than 60 minutes per day, may have been too short to affect BMD. A dosage from 4 to 5 hours23 to 7.5 hours41 per week was needed to maintain/increase BMD. On the basis of animal studies, as reviewed by Stuberg,23 short bouts of 10 to 15 minutes for a total of 60 minutes per day should have equal or superior benefits to a single bout lasting 60 minutes.
In children with CP, a 50% increase in supported standing time resulted in a 6% increase in vertebral BMD, with no change in proximal tibial BMD.42 However, 20 of the 26 participants did not reach the goal of a 50% increase in standing time. Twelve of the 26 participants actually decreased their standing time in the intervention phase.
Researchers in 1 study45 found that combining standing with WBV produced nearly an 18% increase in BMD of the tibia. Stark et al28 reported similar results, whereas Ruck et al43 found that BMD increased in the control group and decreased in the WBV group. Children who are not standing are at risk for low BMD; therefore, standing may be an appropriate intervention to increase BMD. However, other factors need to be considered: overall physical activity levels and intensity, adequate nutrition, calcium and vitamin D levels, thyroid hormone levels, effect of antiseizure and other medications that could cause calcium to leach, adequate daily exposure to sunlight, and BMD-building medications.47–49
Clinical recommendation from the evidence. Although the level 2 to 4 studies supported the use of standing devices to positively affect BMD at some sites, but not all, none of the published level 3 to 4 studies included findings relevant to clinical dosing recommendations.
Other considerations (authors’ opinions). Standing for 60 to 90 minutes, 5 times per week, may be a minimum threshold for positively affecting BMD.41 This may mean that some portion of the program should occur at school in addition to home. Avoid discontinuing standing programs during school breaks.44 When transitioning to a new school, group home, or program, a physical therapist should assist with continued access to standing equipment and training of new personnel. The onset of puberty may be a critical period to maintain or begin a supported standing program.39 Consult with an experienced nutritionist to ensure adequate intake of calcium, vitamin D, and other nutrients.39 Ensure adequate daily exposure to sunlight or equivalent, especially during winter months.39 Consult with an experienced physician about effects of other medications on BMD.39 Consult with an experienced physician to consider the use of BMD-increasing medications.39 A previous pathological fracture places the child at the highest priority for receiving a rehabilitative standing program.39 Multiple short bouts that include loading and unloading, for example, sit-to-stand transfers, may be more valuable than static standing alone.23 Ensure that the child is weight-bearing symmetrically by adjusting positioning devices with maximal, but comfortable, hip and knee extension.37,38 Use as few postural supports and straps as needed to fully load the legs.37,38
Activities and Participation (Mobility d410 to d489 and Major Life Areas d810 to d859)
Evidence at levels 2 to 5. As shown in Table 11, the use of a stander may have increased the speed of feeding,50 improved interactions with peers and caregivers,2,51 promoted social interaction,4 and eased the burden of care.18 For gait, the use of a stander improved the base of support21 and increased walking speed,20,43 including an improved stride length, stride time, stance phase time, and double support time.20 The use of a supported standing program was also shown to improve scores on the Gross Motor Function Measure.28,31 Standing also improved scores on standardized tests6 and slightly improved some work output.52
Clinical recommendation from the evidence. Standing combined with WBV for 60 minutes, 5 times per week, may improve function in children with CP.28
Other considerations (authors’ opinions). Pair standing with an activity or participation by using a toy, communication device, or other learning tool. To promote participation in upright activities, use a stander to place the child at eye level with peers. Choose a self-propelled or power-driven standing wheelchair to promote movement activities with peers.
CONCLUSIONS AND DISCUSSION
The strongest evidence-based literature supported the use of standing devices to positively affect BMD at some sites (but not all), lower extremity ROM, hip biomechanics, and spasticity. Whole-body vibration appears to be a promising addition, but more studies are needed to look at the optimal parameters (hertz, amplitude, oscillation, etc).29 In only 2 studies19,41 was dosing for pediatric supported standing programs directly addressed. Martinsson and Himmelmann19 showed positive benefits of 60 and 90 minutes of supported standing per day on hip migration, but no changes at 30 minutes per day. Katz et al41 demonstrated positive results on BMD with 10 hours of supported standing per week, but not when the dosage fell below 7.5 hours per week.
Although standing devices were shown in this review to be medically useful, further research and discussion is needed. Improving BMD has not been shown to improve activity and/or participation. Some authors39,41 allude to low BMD resulting in pain. If so, this might justify supported standing because children who are nonambulatory and have already experienced a pathological fracture are at greater risk for additional fractures.
In spite of the questions that remain after this evidence-based review, we think enough support exists for the use of a standing device as part of a comprehensive 24-hour postural management and activity program for children who are not active in an upright position, nonambulatory, and/or minimally ambulatory, provided no contraindications exist. Therapists recommending a 24-hour postural management program should consider including both a passive standing component, using a prone, supine, and/or upright stander, and an active component using a stander that steps, vibrates, oscillates, sways, turns, bounces, moves from sit-to-stand under users’ own power, allows users to self-propel, and so on, or other devices that combine weight-bearing and movement such as a gait trainer/support walker.
The ICF-CY model encourages practitioners and therapists to focus on activity and participation. When we look to improve body functions and structure, it should always be in the context of improving activity and participation within the individual's environment. To meet these goals for a child who is nonambulatory, Gross Motor Function Classification Scale levels 4 or 5, using a standing device, may be an excellent starting point.
Although further research on dose–response relationships between pediatric supported standing programs and desired outcomes is certainly needed, current evidence indicates that children with neuromuscular dysfunction who were not physically active could benefit from standing 5 days per week under the following conditions: (1) to improve BMD, 60 to 90 min/d; (2) to improve hip biomechanics, 60 min/d in 30° to 60° of bilateral hip abduction; (3) to increase ROM, 45 to 60 min/d; and (4) to minimize the effects of spasticity, 30 to 45 min/d. Future research should define minimal and optimal doses for desired outcomes in defined pediatric populations.
Continued challenges remain to fully define an ideal supported standing program. Overall, the dose–response relationship for supported standing is not defined for some outcome variables that have been assessed. Survey and qualitative studies reflect a belief that standing improved cardiopulmonary function, alertness, bowel function, and participation. The effect of supported standing on these outcomes, however, has not yet been systematically studied.
Limitations of this current review included very minimal pediatric dosing literature, lack of higher levels of evidence from which to extract potential dosing recommendations for any population, and authors’ subjectivity in the choices for search and classification parameters, interpretation of the literature, and for the specific clinical recommendations/author comments. Given these limitations, clearly more research, ranging from higher-level research studies to well-described case reports, is necessary to define important outcomes, describe clinical reasoning, and determine the effect of standing programs on the participation of children with whom we work.
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