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The Relationship Between Sitting Stability and Functional Performance in Patients With Paraplegia Chiung-Ling Chen, MS, OT, Kwok-Tak Yeung, MA, OTR, Liu-Ing Bih, MD, Chun-Hou Wang, BS, PT, Ming-I Chen, BS, OT, Jung-Chung Chien, BS, OT ABSTRACT. Chen C-L, Yeung K-T, Bih L-I, Wang C-H, Chen M-I, Chien J-C. The relationship between sitting stability and functional performance in patients with paraplegia. Arch Phys Med Rehabil 2003;84:1276-81. Objectives: To compare sitting stability between patients with high and low thoracic spinal cord injury (SCI), to determine the factors that can predict sitting stability, and to examine the relationship between sitting stability and functional performance. Design: Cross-sectional assessment was performed on subjects with paraplegia. Setting: Rehabilitation hospital affiliated with a medical university. Participants: Convenience sample of 30 adults with complete chronic thoracic SCI. Interventions: Not applicable. Main Outcome Measures: (1) Postural sway during quiet sitting over 30 seconds was recorded as static sitting stability, and composite maximal weight-shift during leaning tasks over 30 seconds was measured as dynamic sitting stability; (2) age, body weight, trunk length, trunk strength, postonset duration, injury level, and presence of spasticity were examined as predictive variables for sitting stability; and (3) the time for completion of upper- and lower-body dressing and undressing and transfer was measured as functional performance. Results: A significant difference in composite maximal weight-shift was found between high and low thoracic SCI subjects (t⫽2.90, P⬍.01). Injury level and trunk length were 2 important predictive factors for dynamic sitting stability, and they explained 43.5% of the variance. Only the completion time of upper-body dressing and undressing correlated significantly with static (r⫽.465, P⫽.01) and dynamic (r⫽⫺.377, P⬍.05) sitting stability. Conclusions: The subjects with low thoracic SCI showed better dynamic sitting stability than those with high thoracic SCI. Injury level and trunk length, not trunk flexion or extension strength, predicted the outcome of dynamic sitting stability. Measures were not precise enough to predict functional performance from the viewpoint of injury level and sitting stability. The underlying premise that a reduction or increase in trunk strength is indicative of poorer or better sitting stability in SCI individuals is questioned, and implications for problem identification and treatment planning are discussed.
From the Rehabilitation Hospital and the Schools of Occupational Therapy (C-L Chen, Yeung, M-I Chen, Chien), Physical Therapy (Wang), and Rehabilitation Medicine (Bih), Chung Shan Medical University, Taichung, Taiwan, ROC. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Kwok-Tak Yeung, MA, OTR, Sch of Occupational Therapy, Chung Shan Medical University, 110, Section 1, Chien-Kuo N Rd, Taichung, Taiwan 402, ROC, e-mail:
[email protected]. 0003-9993/03/8409-7680$30.00/0 doi:10.1016/S0003-9993(03)00200-4
Arch Phys Med Rehabil Vol 84, September 2003
Key Words: Activities of daily living; Paraplegia; Posture; Rehabilitation; Spinal cord injuries. © 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation O MAINTAIN POSTURAL stability is to keep or return the center of body mass over the base of support in a T position or during changes in position. It is a complex process involving the coordinated actions of biomechanical, sensory, motor, and central nervous system components.1 In patients with spinal cord injury (SCI), motor performance may be impaired by muscular weakness and disturbance in somatosensory input, resulting in impairment of postural stability, even in sitting position. Sitting balance is believed necessary in performing functional activities from a seated position. Several prognostic studies have shown that sitting balance is a valid predictor for functional outcome in patients with brain injury2 or stroke.3-6 Sitting balance also can predict the ability to walk in patients with stroke7 and spina bifida.8 However, Nichols et al9 found only a poor to moderate relationship between the functional scores of the FIM™ instrument and sitting balance measures in patients with hemiparesis. For individuals with paraplegia, most functional activities, such as eating, dressing, and transferring, are performed in a seated position. The amount of trunk stability and mobility is directly correlated with the patient’s ability to perform functional tasks. To regain sitting postural control is 1 aim in the rehabilitation of patients with paraplegia.10,11 Many outcome studies12-17 of patients with SCI have focused on motor, sensory, and functional recovery rather than postural stability. A few studies18-20 on the sitting postural control of patients with paraplegia have focused on compensatory postural muscle activities and changes in postural motor programming during reaching tasks. These studies18,19 showed that patients with thoracic SCI try to compensate for the loss of postural muscle function of the erector spine through increased use of different nonpostural muscles. Seelen et al20 reported that patients with low thoracic SCI, having more residual sensorimotor functions, seem to adopt more complex strategies for maintaining and restoring sitting balance and that these strategies take longer to specify and to program. Patients with high thoracic SCI seem to rely on simpler strategies that use more passive postural support. Few studies have quantitatively analyzed sitting stability in terms of postural sway and weight shifting in patients with paraplegia or addressed sitting stability in relation to functional performance. The purposes of the present study were (1) to quantify and compare the sitting stability between patients with high and low thoracic SCI, so that the magnitude of the impairment could be defined; (2) to determine factors that predict sitting stability; and (3) to examine the relation among injury level, sitting stability, and functional performance. We hypothesized that patients with low thoracic SCI would have better sitting stability than patients with high thoracic SCI and that the injury level and trunk strength would be the factors that
SITTING STABILITY AND FUNCTIONAL PERFORMANCE, Chen
Fig 1. Setup for sitting stability tests showing the Balance Performance Monitor, hard wood stool, subject, and researcher positions.
affected sitting stability. We also hypothesized that patients with lower injury level and better sitting stability would complete functional activities in less time. METHODS Participants Patients with a diagnosis of complete SCI and 1 year postonset were recruited from the Spinal Cord Injury Association of central Taiwan. Thirty subjects without any obvious contractures were selected for this study. Each subject signed an informed consent form before participation in the study. Demographic data, including age, sex, cause of injury, and years of postonset, were obtained and recorded. The study group consisted of 27 men and 3 women. Subjects ranged in age from 20 to 57 years (mean ⫾ standard deviation [SD], 33.97⫾10.7y), and the median duration of their disabilities was 7.05 years (range, 1.2–20y). The neurologic injury levels ranged from T3 to T12. Of the 30 subjects, 15 were injured in traffic collisions, 7 were injured by falls, and 4 were injured by penetration. The remaining 4 subjects had an unclassified cause of injuries. Instruments Sitting stability was measured by the Balance Performance Monitora (fig 1). This monitor is a portable device that assesses the weight-bearing status of a subject seated on a seat force plate. Four dynamic force transducers that measure vertical force are mounted beneath the seat. The monitor’s computer software gathers data from the forceplate and calculates postural sway during quiet sitting and the amplitude of weightshift during leaning tasks over 30 seconds. The results are displayed graphically. A stopwatch was used to record the completion time for a task in seconds. The 3 selected functional tasks were upperbody dressing and undressing, lower-body dressing and undressing, and transfer. These tasks were chosen because sitting stability is considered an important determinant in performing these skills. Procedure After providing informed consent and demographic data, each subject underwent a physical examination that included
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sitting stability, transfer, and dressing and undressing. Subjects did not perform the tests in a specific sequence and could rest between tests as needed. Physical examination. Anthropometric variables, including trunk length and body weight, were measured and recorded. Trunk length was measured with a tape measure from the C7 vertebra to the coccyx.21 Brief neurologic and musculoskeletal examinations were performed. Each subject’s neurologic injury level and the presence of spasticity were documented. Neurologic injury level and its completeness were defined according to the standards of the American Spinal Injury Association.22 Spasticity was assessed through passive limb movement and recorded as present or absent. The Ashworth Scale or the Modified Ashworth Scale (MAS) are the measurement tools most used clinically to rate spasticity. However, previous studies have shown that more problematic spasticity occurs among SCI patients with motor-incomplete lesions than in those with motor-complete lesions,23 particularly in persons with a cervical level of injury.24 Maynard et al25 found a lower incidence of spasticity development among subjects with lower thoracic and lumbosacral levels of injury. Furthermore, Haas et al26 reported that the Ashworth Scale was slightly more reliable than the MAS. They also suggested that the Ashworth Scale is of limited use in the assessment of spasticity in the lower limbs of patients with SCI. For the purpose of the present study, we considered that the methods used were sufficient to detect the state of spasticity. The musculoskeletal examination included passive joint range of motion (ROM) and trunk strength. The passive joint ROM was performed to determine the presence of contractures or deformities in the lower extremities. To test trunk strength, we used a procedure modified from that used by Hardcastle et al.27 In their study, the subjects were placed in their own wheelchairs and asked to sit without using any hand support. Trunk flexion and extension strength was measured with a myometer. In the present study, we used a handheld dynamometer, Nicholas Manual Muscle Tester (model 01160),b to measure maximal isometric strength of trunk flexion and extension in kilograms of force. The subject was seated on a mat table in a long sitting position without support. The dynamometer was placed proximal to the midline of the sternum, and the subject was then asked to push against the dynamometer at maximal effort. At the same time, the examiner applied force to break the subject’s effort. The peak force shown on the dynamometer was recorded as the subject’s trunk flexion strength. After 3 readings were taken, the mean score was recorded and normalized to body weight to represent the strength score of trunk flexion. The same procedure was used to measure the trunk extension strength, except that the dynamometer was placed in a posterior position at the subject’s interscapular region and the subject was asked to push back as hard as possible. Sitting stability tests. The subject was transferred and seated on the forceplate, which was placed on the top of a hard wood stool of appropriate height. The subject was positioned centrally left and right to accommodate the shape of the seat. To determine the central position for forward and backward required the researcher’s judgment because that point varied among subjects. The subject’s hip, knee, and ankle were kept at 90°, and the height of the foot support was adjusted to each individual’s anthropometric measurements (see fig 1). To measure static sitting stability, subjects were asked to maintain a static sitting position without support for 30 seconds. For dynamic sitting stability, leaning tasks were performed in 4 directions (forward, backward, left, right). Subjects were asked to lean forward as far as possible to the point where they could retain sitting balance without support for 30 seconds. They Arch Phys Med Rehabil Vol 84, September 2003
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SITTING STABILITY AND FUNCTIONAL PERFORMANCE, Chen Table 1: Characteristics of Subjects With High and Low Thoracic SCI Variable
Age (y) Weight (kg) Trunk length (cm) Trunk flexion strength score* Trunk extension strength score* Postonset duration (y) Presence of spasticity (n) Yes No
High Thoracic SCI (n⫽8)
Low Thoracic SCI (n⫽22)
P Value
30.38⫾10.10 56.25⫾7.92 64.69⫾3.08 .15⫾.03 .14⫾.02 8.18⫾5.85
35.27⫾10.84 64.37⫾11.11 64.80⫾3.55 .20⫾.07 .17⫾.08 6.73⫾4.96
.275† .069† .940† .108† .430† .507†
6 2
7 15
NOTE. Values are mean ⫾ SD. *Trunk flexion and extension strength were normalized against body weight. † Not significant by the independent t test.
were then asked to lean backward, to the right, and to the left sequentially. Their arms could extend to the opposite side to help maintain balance. Subjects practiced each movement before the actual tests to familiarize themselves with the tasks and to find their own limits of stability. During the testing of sitting stability, a researcher guarded the subjects for safety (see fig 1). The test was repeated if the subject regained trunk balance with arm or hand support. Transfer. The transfer test was performed between a standard-height wheelchair without armrests and an adjacent mat table of the same height. The wheelchair was equipped with a solid seat and a sling backrest; no cushion was used. The subjects were instructed to execute transfer from and to the wheelchair in their normal fashion. They were timed as they transferred to the mat table. The recording of timing began with the subject’s first move from the starting position in the wheelchair and ended when the subject lay supine on the mat table. The starting position was with the subject sitting all the way back in the wheelchair. Subjects were timed again as they transferred back to the wheelchair. Subjects were asked to rise from a supine position on the mat table, transfer to the wheelchair, and sit in the chair until they sat completely back in the chair. The time to perform these 2 tasks was added as a single score. Each subject performed 3 trials, and we calculated the mean time for the score of transfer. Dressing and undressing. To perform the upper- and lower-body dressing and undressing, a pullover shirt and a pair of elastic waist pants were used. The subject was long-seated on the mat table with hands placed on both sides. The researcher placed the shirt on the subject’s legs and started timing. Timing ended when the subject pulled down the shirt and adjusted it. The subject was again timed while removing the shirt. The subject was asked to take off the shirt, adjust it, and place it back on his/her legs. Timing ended when the subject assumed the original starting position. The time to dress and undress was totaled as a single score. Each subject performed 3 trials, and we calculated the mean time for the score of upper-body dressing and undressing. Similar test procedures were performed for lower-body dressing and undressing, and its score was obtained accordingly. All subjects were asked to perform the functional tasks as quickly as possible but safely to retain balance. Statistical Analysis The postural sway of static sitting for 30 seconds was derived from the Balance Performance Monitor’s sway coefficient as an indicator of static sitting stability. The sway coefArch Phys Med Rehabil Vol 84, September 2003
ficient was calculated as the SD of the mean weight-shift over the 30 seconds. The higher the value, the higher the deviation and the greater the impairment of sitting balance. Two sway coefficients represent the anteroposterior and lateral components of sway,28 and we totaled them for a score. Maximal amplitude of weight-shift in leaning tasks during 30 seconds was calculated and expressed as a percentage change in bodyweight distribution derived from the graph presentation. Each measurement was obtained by measuring the distance between the initial position and maximal displacement in 4 directions with a ruler. The measurement was expressed as a percentage derived from the measuring distance in millimeters, and each 16-mm block represented 10% of body-weight distribution. A composite score summing the 4 maximal weight-shift measures was calculated as an indicator of dynamic sitting stability. We used the independent t test to analyze the difference in sitting stability between high and low thoracic SCI groups. Subjects with T1 to T6 paraplegia were in the high thoracic SCI group, and subjects with T7 to T12 paraplegia were in the low thoracic SCI group. Pearson product-moment correlations were calculated to determine the relation between independent variables and sitting stability. Stepwise multiple regression determined which set of independent variables could best predict sitting stability. Age, weight, trunk length, trunk flexion and extension strength, years of postonset, injury level, and presence of spasticity were counted as independent variables. The injury level was recorded as an ordinal variable. Each injury level was assigned a number from 1 to 12; for example, T1 equals 1 and T10 equals 10. Spasticity was recorded as a dichotomous variable (ie, present or absent). To examine the relation among injury level, sitting stability, and functional performance, Pearson product-moment analysis was used to determine the correlation between sitting stability and the time to complete the functional activities. Spearman rank-order correlation coefficient analysis was also used to determine the correlation between injury level and the completion time of functional activities. An ␣ value of .05 was considered significant for all statistical analyses. RESULTS Eight subjects were included in the high thoracic SCI group, and 22 subjects were in the low thoracic SCI group. None of the subjects had obvious contractures or deformities that would prevent them from assuming the sitting position. The clinical characteristics of the 2 groups are in table 1. No significant differences were found between the 2 groups for age, weight, trunk length, trunk strength, or years of postonset.
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SITTING STABILITY AND FUNCTIONAL PERFORMANCE, Chen Table 2: Comparison of Sitting Stability in Subjects With High and Low Thoracic SCI Outcome Measurement
Static sitting stability Postural sway (%) Dynamic sitting stability Composite maximal weight-shift (%)
High Thoracic SCI (n⫽8)
Low Thoracic SCI (n⫽22)
P Value
4.06⫾2.72
3.80⫾1.30
.786*
42.70⫾13.99
61.51⫾16.24
.007†
NOTE. Values are mean ⫾ SD. *Not significant by the independent t test. † Significant at P⬍.01 by the independent t test.
Sitting Stability of High and Low Thoracic SCI Subjects The means and SDs of the sitting stability scores for both SCI groups are in table 2. Comparing the sitting stability for the 2 groups, we found no significant difference in static postural sway (t⫽.26, P⬎.05), whereas a significant difference in composite maximal weight-shift was found (t⫽2.90, P⬍.01). It seems that low thoracic SCI subjects had better dynamic sitting stability than high thoracic SCI subjects did. Predictive Factors for Sitting Stability The correlation analysis showed that no single independent variable correlated significantly with static sitting stability. The correlation coefficients ranged from .065 to .303. In contrast, the injury level correlated significantly with dynamic sitting stability (r⫽.554, P⬍.01) and trunk flexion strength (r⫽.489, P⬍.01). The stepwise multiple regression analysis showed that dynamic sitting stability could be predicted (P⬍.05) by the independent variables. Regression analysis showed that injury level and trunk length were significant predictors of dynamic sitting stability. These 2 factors explained 43.3% of the variance in dynamic sitting stability (table 3). Relations Among Injury Level, Sitting Stability, and Functional Performance The mean scores of completion times for the functional activities were 19.18⫾6.25 seconds for upper-body dressing and undressing, 53.69⫾18.56 seconds for lower-body dressing and undressing, and 28.75⫾21.78 seconds for transfer. The correlation matrix describing the association among the measures is shown in table 4. Only the completion time of upperbody dressing and undressing correlated significantly with injury level (r⫽⫺.408, P⬍.05), static sitting stability (r⫽.465, P⫽.01), and dynamic sitting stability (r⫽⫺.377, P⬍.05). Injury level, static sitting stability, and dynamic sitting stability did not correlate significantly with the completion time of transfer or lower-body dressing and undressing. DISCUSSION Impaired sitting stability in people with SCI seems to be related to defective motor performance. Function of abdominal and paraspinal extensor muscles from partial to full innervations varies with the neurologic level. It has been hypothesized
Table 3: Stepwise Multiple Regression for Predicting Dynamic Sitting Stability Variable
R2
Neurologic level .344 Trunk length .433 *Significant at P⬍.05.
Adjusted R2
.320 .391
F
B

t
14.66* 3.168 .584 4.03* 10.31* ⫺1.558 ⫺.299 ⫺2.06*
that the subjects with low thoracic SCI will have better sitting stability because they have more residual muscles innervated than the subjects with high thoracic SCI do. However, the present study’s results showed no significant difference in static sitting stability between the 2 groups. Moreover, no significant correlation was found between injury level and static sitting stability. This finding may be attributed to the ceiling effect in measuring static sitting stability. Dynamic sitting stability presents a more challenging activity for persons with paraplegia and is more sensitive in detecting sitting instability between the high and low thoracic SCI groups. The magnitude of impairment of sitting balance among patients with different levels of lesions might need further investigation. Our second hypothesis, that trunk strength and injury level are important predictors of sitting stability, was not fully supported. The results of the regression analysis indicated that trunk flexion or extension strength did not significantly influence sitting stability in SCI subjects. In a study of elderly men, Iverson et al29 reported a significant correlation between isometric hip muscle strength and the ability to maintain balance. However, researchers who have studied the relations between muscle strength and postural control among elderly adults have reported that to be a low correlation.30-32 They suggested that postural muscle control, rather than muscle force development, may be a critical variable in determining postural control. Coordination of central and peripheral afferent and efferent signals, as well as muscle fiber function, is needed to maintain postural stability. Patla et al33 believed that substantial muscle activation or strength was not required to maintain doublestance stability. Our inability to find a significant correlation between trunk strength and sitting stability indicated that maximal isometric contraction of trunk muscles was not critical to maintaining sitting stability. Therefore, therapists should not assume that treating deficits in trunk strength would necessarily improve sitting stability. Instead, therapists should treat trunk muscle weakness and sitting instability as independent problems amenable to muscle strengthening and postural control training. It is interesting to observe that the trunk length was a major factor for predicting dynamic sitting stability. Trunk length negatively correlated with dynamic sitting stability; that is, the longer the trunk, the smaller the composite maximal weightshift. In the present study, the measure of maximal weight-shift in 4 directions by the leaning tasks performed while sitting was similar to the measure of center of pressure (COP) excursion while standing. COP excursion is measured with the subject standing on a force platform and is recorded as the subject leans forward, backward, and sideways.34 Functional reach, a measurement of the margin of stability, is biomechanically analogous to the COP excursion. Duncan et al,21 who designed the test, reported that age and height are the most significant Arch Phys Med Rehabil Vol 84, September 2003
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SITTING STABILITY AND FUNCTIONAL PERFORMANCE, Chen Table 4: Correlation Matrix Among Injury Level, Sitting Stability, and Functional Performance Sitting Stability Variable
Injury Level
Injury level Sitting stability Postural sway Maximal weight-shift Functional performance UBD/U LBD/U Transfer
Postural Sway
⫺.155
Functional Performance Maximal Weight-Shift
.554
†
⫺.055
UBD/U
LBD/U
Transfer
⫺.408*
⫺.086
⫺.247
.465† ⫺.377*
.230 ⫺.288
.264 ⫺.249
.552†
.772† .615†
Abbreviations: UBD/U, upper-body dressing and undressing; LBD/U, lower-body dressing and undressing. *Significant at P⬍.05; †significant at P⬍.01.
factors that influence functional reach. The taller the subject, the greater the distance of functional reach. It was presumed that the longer the trunk length, the greater the composite maximal weight-shift would be. The disparate results correlate with decreased pelvic and trunk stability secondary to trunk and hip musculature paralysis in patients with paraplegia. Duval-Beaupere and Robain35 reported that the center of gravity (COG) was higher by 5% of the body length in their patients with paraplegia than in the normal subjects. This upward displacement of the COG reflects a disproportional loss of lower-body weight. Such a change in COG must lead to a loss of sitting stability and may contribute to the change in a person’s limit of stability. Therefore, we assumed that a subject with a longer trunk length may have a higher COG and may come to have a lesser extent of stability limits, as shown by the smaller amplitude of the weight-shift. In the present study, a continuous scale measurement of functional performance was more sensitive than the ordinal scoring of functional scale (eg, FIM).36 Also, because the continuous scale measurement is applicable to a wide range of functional levels with minimal ceiling effect, it may be able to distinguish precisely the levels of “functional disabilities.” The poor sitting stability found in subjects with paraplegia may result from limited upper-extremity function.37 These functions include upper-body dressing, reaching for lower-body dressing, and, possibly, the ability to transfer. However if the trunk muscles are strong enough to maintain sitting stability, one might expect that the completion time of dressing and undressing and transfer would be shorter. The results of the present study indicate that only the completion time of upper-body dressing and undressing correlated significantly with injury level and the 2 measures of sitting stability. Static sitting stability correlated more than dynamic sitting stability with the completion time of upper-body dressing and undressing. The specific functional pattern of upper-body dressing and undressing may explain this finding. When performing upper-body dressing and undressing in a long sitting position on the mat table without support, it is crucial to maintain the COG within a small zone of limited weight-shift for optimal upper-extremity function. The act of keeping the trunk as stable as possible while dressing and undressing the upper body is similar to the test for static sitting stability. The low correlation between sitting stability and the other 2 functional activities may be explained by factors other than sitting stability. The skills of lower-body dressing and undressing and transfer are more complex than those of upper-body dressing and undressing. We observed that lower-body dressing and undressing requires more steps. While performing lower-body dressing and undressing, subjects must lie supine, begin a series of rolls to pull Arch Phys Med Rehabil Vol 84, September 2003
over or push down a pair of pants across the buttocks, and then sit up to the original starting position.38 For the transfer activity, many biomechanical factors—such as body build, ROM, muscle strength, hand placement, and the degree and force of head and trunk motion—have been associated with the ability to transfer.39 In addition to these factors, Allison et al40 reported that at least 2 movement strategies adopted by individuals with SCI when transferring account for the variability in the factors associated with the ability to transfer. It was hypothesized that more steps are needed in lower-body dressing or that the contributing factors of transfer may diminish the importance of sitting stability for lower-body dressing and undressing and transfer. In this study, the timing of a series of functional tasks was used to assess subjects’ functional performance. We believe that the ability to complete a particular activity in a specified period of time provides important information on a patient’s overall ability. However, time scores alone do not always yield the complete functional picture. Because speed does not equate with function, various behaviors that are characteristic of function, such as dependence level, difficulty, coordination, efficiency, and endurance, must be considered in the overall analysis.41 In general, it is difficult to predict the degree of disability exclusively from knowledge of neurologic levels and a patient’s sitting stability. It is also inappropriate to determine levels of function or rehabilitation goals entirely according to a patient’s neurologic level of injury and sitting stability. CONCLUSIONS The results of the present study suggest a significant difference in dynamic sitting stability between subjects with high and low thoracic SCI. Low thoracic SCI subjects show better maximal weight-shift in leaning tasks. The injury level and trunk length are 2 important factors affecting a person’s dynamic sitting stability. Sitting stability and injury level both correlated significantly with the completion time of upper-body dressing and undressing, but not with the completion time for lower-body dressing and undressing and transfer. These results imply that various factors must be examined when functional skills assessments of patients with SCI are interpreted. Each functional task requires adequate strength, joint ROM, and postural control to perform the motion involved. However, a program limited to strengthening, ROM exercises, and postural control training will not result in the development of functional skills. Besides these physical prerequisites, each functional task involves the factors of body build and the performance of a set of skills. Functional inde-
SITTING STABILITY AND FUNCTIONAL PERFORMANCE, Chen
pendence requires all of these physical and skill prerequisites to be developed.39,42 Acknowledgments: We thank Jiun-Nan Tsai, BS, OT, and MingShun Wu, BS, OT, Department of Occupational Therapy, Taichung Rehabilitation Hospital, for their assistance with data collection. We also thank Edward Yang, MD, PhD, and Guey Fang Jih, PhD, OTR, for their assistance in the preparation of the manuscript. References 1. Horak FB, Shumway-Cook A. Clinical implications of postural control research. In: Duncan PW, editor. Balance. Alexandria: American Physical Therapy Association; 1990. p 105-11. 2. Black K, Zafonte R, Millis S, et al. Sitting balance following brain injury: does it predict outcome? Brain Inj 2000;14:141-52. 3. Kwakkel G, Wagenaar RC, Kollen BJ, Lankhorst GJ. Predicting disability in stroke—a critical review of the literature. Age Ageing 1996;25:479-89. 4. Sandin KJ, Smith BS. The measure of balance in sitting in stroke rehabilitation prognosis. Stroke 1990;21:82-6. 5. Wade DT, Hewer RL. Functional abilities after stroke: measurement, natural history and prognosis. J Neurol Neurosurg Psychiatry 1987;50:177-82. 6. Wade DT, Skilbeck CE, Hewer RL. Predicting Barthel ADL score at 6 months after an acute stroke. Arch Phys Med Rehabil 1983; 64:24-8. 7. Feigin L, Sharon B, Czaczkes B, Rosin AJ. Sitting equilibrium 2 weeks after a stroke can predict the walking ability after 6 months. Gerontology 1996;42:348-53. 8. Swank M, Dias LS. Walking ability in spina bifida patients: a model for predicting future ambulatory status based on sitting balance and motor level. J Pediatr Orthop 1994;14:715-8. 9. Nichols DS, Miller L, Colby LA, Pease WS. Sitting balance: its relation to function in individuals with hemiparesis. Arch Phys Med Rehabil 1996;77:865-9. 10. Nixon V. Spinal cord injury: a guide to functional outcomes in physical therapy management. Rockville: Aspen; 1985. p 23-36. 11. Farmer AR. Setting goals. In: Hill JP, Intagliata S, editors. Spinal cord injury: a guide to functional outcomes in occupational therapy. Rockville: Aspen; 1986. p 19-23. 12. Yarkony GM, Roth EJ, Heinemann AW, Lovell L, Wu YC. Functional skills after spinal cord injury rehabilitation: three-year longitudinal follow-up. Arch Phys Med Rehabil 1988;69:111-4. 13. Yarkony GM, Roth EJ, Meyer PR, Lovell LL, Heinemann AW. Rehabilitation outcomes in patients with complete thoracic spinal cord injury. Am J Phys Med Rehabil 1990;69:23-7. 14. Waters RL, Yakura JS, Adkins RH, Sie I. Recovery following complete paraplegia. Arch Phys Med Rehabil 1992;73:784-9. 15. Daverat P, Petit H, Kemoun G, Dartigues JF, Barat M. The long term outcome in 149 patients with spinal cord injury. Paraplegia 1995;33:665-8. ¨ ztu¨ rk Y, et al. Motor, sensory and 16. Mu¨ slu¨ manog˘ lu L, Aki S, O functional recovery in patients with spinal cord lesions. Spinal Cord 1997;35:386-9. 17. Dzidic I, Moslavac S. Functional skills after the rehabilitation of spinal cord injury patients: observation period of 3 years. Spinal Cord 1997;35:620-3. 18. Seelen HA, Vuurman EF. Compensatory muscle activity for sitting posture during upper extremity task performance in paraplegic persons. Scand J Rehabil Med 1991;23:89-96. 19. Seelen HA, Potten YJ, Huson A, Spaans F, Reulen JP. Impaired balance control in paraplegic subjects. J Electromyogr Kinesiol 1997;7:149-60. 20. Seelen HA, Potten YJ, Adam JJ, Drukker J, Spaans F, Huson A. Postural motor programming in paraplegic patients during rehabilitation. Ergonomics 1998;41:302-16.
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Arch Phys Med Rehabil Vol 84, September 2003
