Hemiplegia

ABSTRACT

The purpose of this study was to determine if joint mobilizations improve ankle mobility and sit-to-stand function in 5 subjects with hemiplegia following stroke (7 to 11 months post-CVA). Methods: Data collection occurred over 13-15 sessions in this single-subject design study, with an initial baseline period of measurements only. Ankle range of motion, ankle kinematics during sit-to-stand, and time to complete the task were measured during every session.The intervention consisted of joint mobilizations to increase ankle dorsiflexion. Results:All subjects demonstrated a statistically significant increase in passive ankle ROM. No consistent trends were found for ankle excursion during sit-to-stand or time to perform the task. Analysis of ankle kinematics revealed varying patterns of change for the individual subjects. Conclusion: Although joint mobilizations were effective at improving ankle motion, these improvements did not appear to directly affect sit-to-stand function.

Key Words: musculoskeletal, range of motion, stroke, sit-to-stand, ankle

INTRODUCTION

Restricted ankle joint range of motion (ROM) is a common impairment for people with chronic hemiplegia sec ondary to a cerebral vascular accident (CVA).1 Increased passive joint stiffness is consistently found at the affected ankle in patients with hemiparesis following CVA compared to the contralateral ankle and to healthy subjects.2-4 This increased stiffness may be caused by the interaction of many complex factors. Central nervous system pathology frequently results in spasticity, or a velocity-dependent increase in stretch reflexes, which contributes significantly to calf muscle hypertonia or stiffness.3,4 Physical therapists frequently focus on the reduction of spasticity through sustained tendon stretching5 or weight bearing activities6 7 although the effectiveness of these techniques at reducing tone or improving joint mobility has not been demonstrated.

Non-neural factors are also known to increase resistance of joint movement and contribute to the development of contractures independent of reflex activity.2,8-10 These non-neural factors include changes in mechanical properties of muscle and connective tissue that result from a loss of active movement11,12 as well as the aging process13-15 in this population. Immobilization has been found to cause increased joint stiffness within one week in a rat model.16 The increased resistance to passive stretch that is commonly attributed to spasticity may thus be secondary to adaptive muscle changes or passive joint stiffness caused by non-neural factors, and these changes may begin soon after sustaining a stroke.

Restricted joint ROM due to connective tissue tightness may be treated by joint mobilization techniques. A treatment approach based on impairments rather than on medical diagnosis, as suggested by the Guide to Physical Therapist Practice,17 encourages the use of techniques to address musculoskeletal restrictions even in a patient with a primary neurologic pathology such as CVA. Joint mobilizations, or passive movement of the articular surfaces, are recommended to help restore normal accessory motion when there is a ROM limitation. 18 Although this intervention has not been studied in subjects with a CVA, it has been recommended as an appropriate treatment for joint hypomobility in children with cerebral palsy.19,20 Ankle joint mobilizations have been found to effectively increase passive ankle ROM in subjects with diabetic neuropathy21 and subjects with acute ankle sprains.22 It is important to address ankle contractures following a CVA because they may make it difficult for people with hemiplegia to move their limb and perform basic functional tasks such as sit-to-stand (STS).

Performance of the STS movement in healthy people follows a typical pattern that involves sequential movement of the head, trunk, and lower extremities. Schenkman et al23 identified key biomechanical events in the movement pattern that indicate 4 phases of rising. Phase I (Flexion Momentum) begins with initiation of head movement and ends before the buttocks lift from the chair seat. Phase II (Momentum Transfer) begins with seat lift off and ends when maximal ankle dorsiflexion is achieved. Phase III (Extension Phase) involves extension of the ankle, knee, and hip joints.This is followed by Phase IV (Stabilization).

The initial position of the foot during STS appears to be critical in healthy subjects of all ages.24-27 If the foot is too far forward, subjects demonstrate increased muscle activity, greater excursion of head movement, increased pressure on hip and knee joints, and increased duration of movement phases when completing the task.After an extensive review of experimental studies investigating the STS task, Janssen et al28 concluded that foot positioning and the use of armrests are major determinants of STS performance. Healthy elderly have been found to use more than 20° of ankle joint excursion during STS.26,29 Subjects with hemiplegia may be unable to place the foot in an optimal weight bearing position and may have subsequent difficulty with the momenturn transfer phase because of unilateral loss of ankle ROM.

Researchers have found that people with hemiplegia tend to distribute their body weight asymmetrically away from their hemiparetic leg30-32 and take a longer time than healthy elderly to stand up from a chair.33-35 Cheng et al30 found that subjects following a CVA who had experienced a fall required a statistically significantly longer time to stand up (4.32 seconds) compared to post-stroke nonfallers (2.73 seconds) and healthy age-matched comparison subjects (1.88 seconds). This longer time may be required to compensate for increased postural sway in both the mediolateral and anteroposterior directions during the STS task found by several researchers.30,33,36,37 The increased difficulty with the STS task demonstrated by subjects with hemiplegia may be caused by multiple factors, including soft tissue restrictions in the lower extremity.

If musculoskeletal restrictions contribute to the increased difficulty that subjects with hemiplegia have with STS function, perhaps joint mobilizations can assist them to rise from a chair more safely and with less effort. The primary purpose of this study was to determine if ankle joint mobilizations would improve ankle mobility and STS function in 5 subjects with chronic hemiplegia following a CVA. A secondary purpose was to examine changes in ankle kinematic patterns that occur with this intervention. The research hypotheses for this study were: (1) joint mobilizations will be effective in increasing passive ankle ROM, and (2) increased ankle mobility will result in greater ankle motion during performance of the STS task and faster time for STS in subjects with hemiplegia following a CVA.

METHODS

This study used a single-subject multiple baseline AB design, repeated with 5 individual subjects, to examine the effect of ankle joint mobilizations on ankle motion and STS function of subjects with hemiparesis following CVA. The rights of these human subjects were protected, and this study was approved by the Institutional Review Boards of Seton Hall University and the University of Medicine and Dentistry of New Jersey.

Subjects

Five subjects, recruited through local rehabilitation centers via posted flyers and presentations to stroke support groups, completed this study. All subjects were adults, diagnosed with a CVA with resultant hemiparesis 6 months to 1 year ago, and able to transfer from a sitting to a standing position without physical assistance. Measurements of ankle dorsiflexion ROM were taken with the knee flexed using a goniometer prior to participation in the study to ensure that subjects had a contracture. Subjects were excluded from the study if they presented with any of the following: (1) ankle joint hypermobility; (2) ankle joint effusion from trauma or inflammation; (3) rheumatoid arthritis, advanced osteoarthritis, unhealed ankle fracture, or neoplasm; (4) language or cognitive deficits that impaired the patients' ability to give informed consent; or (5) simultaneously receiving physical therapy intervention. Once it was determined that an individual subject met the selection criteria, the investigator explained the purpose of the study and all items in the informed consent form. Subject demographics are presented in Table 1.

Apparatus

The Flock of Birds (Ascension Technology, Burlington, Vt) motion analysis system was used with the Motion Monitor software system (Innovative Sports, Chicago, Ill) to analyze ankle motion during the STS task. This electromagnetic tracking system is useful for measuring 3-dimensional joint positions in a clinical setting with a high degree of accuracy.38-40 The position and orientation of receiving antenna sensors are measured with respect to a transmitting antenna at a sampling frequency of 87 measurements per second. The transmitting antenna is fixed in space and is driven by a pulsed direct current. Six degrees of freedom are measured for each receiving antenna, including 3 positions (x, y, and z coordinates) and 3 Eulerian angles (yaw, pitch, and roll).The Motion Monitor software system interfaces with the Flock of Birds sensors and converts the data coordinates to human joint angles through digitization using standardized anthropometrie assumptions.

Reliability of the Flock of Birds system to study joint motion has been found to be very high in the elbow," metatarsophalangeal joint,42 and knee43 as long as the measurement of bony landmarks was standardized. However, there are no published studies of the reliability of using this system to measure ankle joint ROM, and the standardized set up procedure recommended in the software system had to be modified for the subjects in this study. Normally, the subjects would stand in the standard anatomical position, while a sensor is used to digitize the bony landmarks on the limb. Because the subjects in this study had difficulty standing unsupported for a long period of time and were unable to align the hemiplegie limb symmetrically, the set-up procedure was performed with the subject in a seated position. Test-retest reliability was calculated retrospectively for the subjects in this study, using the repeated baseline measurement of peak-to-peak ankle excursion (mean of 8 trials) found prior to introducing the intervention, and the ICC (3,8) was calculated to be 0.82.This is considered to be a good level of reliability.44 The reliability of ankle dorsiflexion measurements using a goniometer was also calculated retrospectively from the baseline sessions, and the ICC (3,1) was found to be 0.95.

Procedures

Study sessions were scheduled 3 times each week at the same time of day in order to standardize the effects of environmental factors.The subjects completed 3 to 6 baseline sessions over a 1 to 2 week period, and 8 to 11 intervention sessions over a 3 to 5 week period as presented in Table 2.A minimum of 3 baseline sessions was determined a priori, and this baseline period was extended if the dorsiflexion ROM measurements varied by more than 2° during the initial 3 baseline sessions.

Measurements

Subjects were seated on a sturdy wooden or plastic chair, at a height individually selected for each subject so that the hip and knee of the nonhemiplegic side were flexed to approximately 90°, and shoes and socks were removed. The heel was placed on the far edge of a 4 inch high platform in order to stabilize the ankle, allow full movement in both plantarflexion and dorsiflexion, and maintain the knee at 90° of flexion. Hypertonicity of the calf musculature was assessed using the Modified Ashworth Scale and a goniometric measurement of ankle dorsiflexion ROM was taken while the subject was seated.

Once these measurements were documented, 2 electromagnetic sensors were applied to the lower leg and foot of the hemiplegic lower extremity. A third sensor was used to digitize the bony landmarks of the lower extremity as directed by the software system. After set-up, this third sensor was secured on the subject's head to mark the onset of forward motion.The transmitting unit was placed so that all of the sensors were within a 36" radius.

In preparation for the STS motion, the subject was given the following instructions: "put your feet as far back underneath you as possible while keeping your heels on the floor," "do not use the armrest of the chair if possible," and "stand at a fast but safe speed." Following 2 practice trials, 8 STS trials were performed with recording of ankle kinematic data. All trials were videotaped for later visual analysis.A 60-second rest period was provided between STS trials as needed. After completing the STS trials, the baseline measurement sessions (A) were concluded.

Intervention

During the intervention sessions (B), ankle joint mobilizations were performed prior to any measurement procedures.The subject was seated in the same chair as described previously with both feet resting on the floor. Joint mobilizations were performed to the proximal tibia-fibula and the distal tibia-fibula in an anterior and posterior direction, and the foot was lifted for mobilization of the talocrural joint in a loose-packed position with an emphasis on gliding the talus posteriorly on the tibia. All joint mobilizations were applied to the hemiplegic lower leg with Grade I or II manual traction and gliding during the first session, and Grade III movements for the remainder of the sessions, as described by Kaltenborn.18 Each mobilization lasted approximately 1 to 2 minutes for a total of 3 to 6 minutes. Following the intervention, the subjects underwent posttreatment measurement procedures using the same methods as described above.

All 5 subjects tolerated the joint mobilization intervention without complication or pain during the course of the study. One of the subjects (B) noted acute onset of low back pain prior to the tenth session, secondary to a loss of balance at home. He chose to continue to participate fully in the study.

Follow-up

Two weeks after discontinuing the intervention, 4 of the 5 subjects returned for measurement procedures as described previously without the provision of any intervention (one subject did not return for the follow up appointment because of a family emergency and was unable to reschedule). The follow up data from one other subject was partially lost secondary to computer error.

Data Analysis

The dependent variables for this study included passive ankle ROM, as measured with a goniometer, ankle motion during STS, and time for STS as measured with the Flock of Birds system and Motion Monitor software.

The onset of the STS movement was identified as the first frame when the sensor on the subject's head moved >1 mm in the forward direction.The end of the STS movement (stable in standing) was identified as the frame when the sensor below the knee moved

The ankle angle data between the onset frame and ending frame were exported to Microsoft" Excel 2000 files for further analysis. Ankle angle over time graphs were generated as depicted in the bottom graph of Figure 1. Peak-to-peak ankle excursion during each trial was identified by the difference between maximum and minimum ankle angle values for each trial, and the means and standard deviation values for the 8 trials collected during each session were computed for each subject.The STS time for each trial was calculated using the number of frames divided by 87 measurements per second, and the mean and standard deviation for the 8 trials in each session were computed.

All the measurements collected for the 5 individual subjects were graphed for visual comparison of the initial baseline sessions to the intervention sessions to determine if there was a change in the measure for each individual subject. Several statistical procedures have been identified to supplement visual analysis and control for the serial dependency found in the repeated measures of a single subject design. The two-standard-deviation band method was applied to the graphs by calculating the mean and standard deviation of data points within the baseline phase, to illustrate changes from baseline to intervention. Two consecutive data points beyond the two-standard-deviation band were used to determine whether there was a significant change in the variable.44

Although the two-standard band deviation method is commonly used, this has been found to be inaccurate when baseline data are variable and is sensitive to extreme values.45 Ottenbacher suggested that a baseline is considered to be stable if 80% to 90% of the data points are within 15% of the mean.46 Because the baseline data for many of the variables did not meet this criterion of stability, the C statistic was also used to supplement visual analysis.The C statistic is a simplified time series analysis that can be used on small data sets to evaluate the effectiveness of interventions.45-49 Statistical significance is determined by dividing C by its standard error, which gives a z value that can be interpreted using the normal probability table for z scores.The C statistic was calculated first for Phase A data to determine whether a statistically significant trend was present in the baseline values. The presence of a trend prior to the introduction of the intervention would indicate a potential threat to internal validity, such as the influence of maturation effects or testing effects on the variable of interest. If a trend was not found, the data from Phase B were appended to the Phase A data and reanalysis was performed. A significant z score would indicate that the trends in phase A and B are different. A one-tailed test with an alpha of 0.05 (z > 1.645) was used according to the methods described by Tryon48 and Blumberg49 to establish statistical significance.

RESULTS

Ankle Range of Motion

Values for passive ankle dorsiflexion are presented in Figure 2. Increased passive ankle dorsiflexion was noted in all 5 subjects after introducing the intervention, and this increased ROM was generally maintained in the follow up sessions 2 weeks after discontinuing the intervention. The mean and standard deviations of all baseline data points compared to the final measurement session was -1.0° to + 12.0° for Subject A, +2.25° to +11.0° for Subject B, -5.7° to +7.0° for Subject C, -10.0° to +6.0° for Subject D, and -3.0° to +10.0° for Subject E. Visual analysis of Figure 2 reveals apparent changes in level and trend once the intervention was introduced for all subjects, and almost all of the intervention data points are above the two-standard-deviation band for all subjects. However, the baseline phases for Subjects A, B, and E did not meet Ottenbacher's criterion for stability.46 Use of the C statistic for baseline values revealed nonsignificant trends during the baseline phase for each subject (z score ranged from O to 1.61) and statistically significant trends when the intervention phase data were added to the analysis (z score ranged from 3.45 to 3.84). Therefore, both forms of statistical analysis are in agreement that passive ankle dorsiflexion changed significantly after introducing the intervention.

Sit to Stand Function

Values for peak-to-peak ankle excursion during STS are presented in Figure 3. Visual analysis of Figure 3 reveals that peak-to-peak ankle excursion did not increase during the intervention phase for any of the subjects, confirmed by the lack of intervention points above the two-standard-deviation band. Subject B did appear to have a significant decrease in peak-to-peak ankle excursion after the intervention was introduced, which would not be expected with concurrent increase in ankle ROM. Only the baseline for Subject D met the criterion for stability, and no significant trends were noted by C statistic analysis (total z score ranged from 0.1 to 1.48) except for Subject B (z score = 2.6). Both forms of statistical analysis were in agreement for analysis of this data. Although all the subjects did have improved passive ankle ROM in the intervention phase, they did not demonstrate a concurrent improvement in the amount of ankle motion used during the STS task.

Time to perform the STS task during both the baseline and intervention phases for all subjects is presented in Figure 4. No significant change is apparent by visual analysis, and almost all of the intervention points are within the two-standard-deviation band for each subject. Only the baseline phase for Subject C met the criterion for stability, and a statistically significant trend during baseline was noted for Subject B using C statistic analysis (z score 1.67). Analysis of the intervention phase data revealed a significant trend (z score 1.67) in a decreasing direction for Subject A, and a significant trend (z score 2.16) in an increasing direction for Subject B. However, the STS time for Subject A did increase back to baseline levels at the 2-week follow up.

A qualitative comparison of ankle kinematics during the STS task was also performed. The ankle flexion pattern of a healthy subject is presented in Figure 5.The values and shape of this curve, which represents ankle angle over time, is similar to that reported in a normative study.50 The starting point of this graph indicates the initial ankle position when the subject initiates STS by moving the head forward (Event 1). As head movement continues forward, the subject plantarflexes slightly (Event 2) to generate forward momentum for the task. After the buttocks lift off the chair, peak ankle dorsiflexion occurs (Event 3).The hip, knee, and ankle then extend into a fully upright standing posture (Event 4). Finally, the subject stabilizes in the standing position (Event 5).

The ankle kinematics of the subjects in this study were compared to the healthy subject shown in Figure 5. Differences between the ankle kinematics in the initial baseline session and the final baseline session for each subject were compared to examine the effect of task practice as part of the repeated measures design during the baseline phase before the intervention was introduced. Differences between the final baseline and the final intervention session were compared to determine the effects of joint mobilizations with continued task practice as part of the repeated measurements. The follow up session was then compared to all of these other sessions to identify whether any changes persisted 2 weeks after discontinuing the repeated measurements and intervention. Eight superimposed trials from each of these sessions are presented for each subject in Figures 6 through 10, along with the same single trial from a healthy subject presented in Figure 5 superimposed in bold on each graph.

A comparison of ankle kinematic data from Subject A is presented in Figure 6. Several trends are apparent on visual analysis. A gradual decrease in inter-trial variability and greater similarity to the normal curve shape appears as the subject progressed through the study. These changes are apparent during the baseline session before the intervention is introduced, continue during the intervention phase, and are not maintained in the follow-up session. Other visually apparent trends for decreased total STS time and decreased time to peak dorsiflexioii during the intervention phase were confirmed by C statistic analysis for this subject.

Ankle kinematic data from Subject B are presented in Figure 7 and show a different trend. Improvements in decreased variability, decreased time for STS, and an earlier peak are noted between the baseline sessions before the intervention is introduced. However the unexpected findings for this subject discussed previously (significant decrease in peak-to-peak ankle excursion and increase in time during the intervention phase) are confirmed through visual inspection of the pattern during the final intervention session.

Subject C did not attend the follow up session, so the ankle kinematic data from the other 3 comparison sessions are presented in Figure 8.The shape of the curves in all the sessions appear similar to that of the healthy subject and to each other, with only minor variations between sessions. Although peak dorsiflexion appears to occur earlier in the final intervention session, this trend was not confirmed with C statistic analysis, and there also appears to be greater inter-trial variability in this session.

Ankle kinematic data from Subject D are presented in Figure 9 and reveal similar trends to those noted in Subject A. A gradual decrease in variability is noted as the subject proceeded through the study, beginning in the baseline phase and continuing once the intervention is introduced. However, unlike Subject A, further improvements in consistency were noted in the follow up session.

There was an error in data collection for the follow up session for Subject E, so the ankle kinematic data from the other 3 comparison sessions are presented in Figure Iu. As with Subject C, the shape of the curves in all the sessions appear similar to that of the healthy subject and to each other, with only minor variations between sessions.

Other indications of changes in STS strategy were noted when observing the trials on videotape and are presented in Tables 3 through 5. Three of the 5 subjects decreased their reliance on armrests to perform STS in the intervention phase compared to the baseline phase (Table 3). The frequency of unsuccessful STS attempts (Table 4) and repositioning of feet (Table 5) decreased for 3 subjects during the intervention phase compared to the baseline phase. In addition, Subject A required physical support to maintain standing balance for 52.1% of the baseline STS trials. The frequency of trials where support was required dropped to 20.8% in the intervention trials.

Finally, several subjects made unsolicited comments regarding the intervention. The subjects noted a sense of greater flexibility and improved ease with gait, stairs, and car transfers. Subject A returned to his physician to request an articulating AFO after completing the study, and Subject B was able to begin using a straight cane in the community instead of a quad cane used previously.

DISCUSSION

The purpose of this study was to determine whether ankle joint mobilizations increased ankle passive range of motion and improved sit-to-stand function in patients with hemiplegia following a CVA. The first research hypothesis was that joint mobilizations would be effective in increasing ankle mobility as measured by passive ROM in patients with hemiplegia. All 5 of the individual subjects participating in this single subject design study demonstrated an increase in ROM when the intervention was introduced.

Normal dorsiflexion ROM has been reported to be 22.75° in people aged 40-49, and 15.39° in people aged 60-84.15 Prior to the intervention, each subject in this study demonstrated significant limitations in ankle motion, with baseline session mean dorsiflexion ranging from -10° (Subject D) to 2.25° (Subject B).The relatively high standard deviations for these baseline measurements were not unexpected. Because hypertonicity in the calf muscles was noted in all subjects, the amount of passive ROM at the ankle may vary according to medication levels, psychological stress, and general health status. For these reasons, there was an attempt to schedule data collection sessions during the same time of day and the number of baseline sessions were extended for some subjects.There is also potential for measurement error using the goniometer and the Flock of Birds system, although retrospective analysis of these baseline measures showed a good level for test-retest reliability (ICC = 0.95 for the goniometric measurements and 0.82 for the peak-to-peak ankle excursion measurements) as mentioned previously.

After participating in the study, all 5 of the subjects had statistically significant trends for increasing dorsiflexion ROM.Three of the 5 subjects (A, B, and E) had equal to or greater than 10° of ankle dorsiflexion during the final intervention session. The other 2 subjects (C and D) began the study with more severe contractures but still improved to equal to or greater than 6° of ankle dorsiflexion by the end of the study. Not only is this magnitude of improvement in passive ROM statistically significant, it is also clinically meaningful because these values are much closer to the ROM required for functional tasks. Approximately 20° of total ankle range of motion is required for normal performance of sit-to-stand transfers,26,29 walking,51 and climbing stairs.52 Furthermore, these improvements were maintained 2 weeks after discontinuing the intervention.

This study revealed that ankle joint mobilizations can improve ankle joint mobility in patients with central nervous system pathology, such as a CVA, in spite of the presence of muscle hyper-reflexia in these subjects.The magnitude of these improvements are comparable to those found by other researchers for patients with decreased ankle motion caused by peripheral nervous system or musculoskeletal pathology.21,22 Both male and female subjects and subjects with CVA in either hemisphere were represented in this study. Although there was sonic variability in functional levels, degree of ankle contracture, and degree of hypertonicity, all of the subjects appeared to benefit from the intervention as demonstrated by an increase in passive ROM. From these results, it seems appropriate to address musculoskeletal impairments such as ankle joint contracture in patients with neurologic pathology. Further study with a larger population is needed to determine which subject characteristics are most likely to benefit from this specific intervention.

The second research hypothesis was that improved ankle mobility would result in improved performance of the sit-to-stancl task. Theoretically, an increase in available ankle motion could result in improved efficiency of movement and decreased time to perform the task.

Although passive ROM at the ankle improved in all 5 subjects, peak-to-peak ankle excursion during the STS task did not increase during the course of this study. It has been demonstrated that healthy elderly have ankle joint excursion during the STS task of 22°26 and 28.7°.29 Subjects A, C, and D demonstrated consistently less ankle excursion than normal during STS during both the baseline and intervention phases. Subjects B and E had excursion values that were comparable to normal during the baseline sessions. Subject B demonstrated a statistically significant downward trend in the intervention sessions, indicating that less ankle excursion was used in the intervention phase than in the baseline phase.This subject experienced the onset of acute low back pain prior to session 10 and, although he chose to continue to participate in the study, his movement strategy for the subsequent sessions was altered secondary to his discomfort.

Because the use of ankle motion during STS by these subjects did not improve, it appears that the joint mobilizations did not contribute to a specific change in STS function. However, during the course of the study these subjects did experience repeated STS practice opportunities by virtue of the repeated measurement design. Although the intent of the baseline sessions was to allow for the subjects to experience repeated practice prior to the intervention, there may have been insufficient practice opportunities. It was assumed that sit-to-stand was a familiar motor task that these subjects performed on a regular basis as part of daily household and community ambulation. However, asking the subjects to stand up while barefoot and without the use of an armrest may have made it a novel task experience. Elderly subjects have been found to move slower on balance and mobility tests when barefooted compared to wearing walking shoes.51 The subjects all reported that they habitually used an armrest to perform the task and had not attempted to stand without one prior to this study. The use of an armrest has been described as an important determinant of the STS movement that may influence foot position and joint excursion.28The subjects may have benefited from prolonged continued practice with gradual attempts at decreasing upper extremity support on the armrest during this study. Functionally-impaired elderly who require use of the armrest may demonstrate an inefficient movement strategy,54 including movement of the feet just prior to the motion as described by Hughes55 and as demonstrated by several subjects in this study. Because all of the subjects used an armrest for at least some of the trials, this may have affected the results of STS performance and the use of ankle motion during the task and would be an important variable to control for in future studies.

The 5 subjects demonstrated different changes in movement strategies during the course of the study. Subject A had the most difficulty performing STS initially. Although he was able to stand up from a sitting position without physical assistance, and therefore met the criteria for inclusion in this study, he did require the use of his cane for support and occasional contact guarding once standing because of unsteadiness. He also used the armrest and repositioned his feet after initiating the movement for a majority of trials in the baseline sessions. The initial STS time of 4.5 seconds in the first baseline session is comparable to the subjects post-CVA who had experienced a fall as described by Cheng.30 Because of the high variability of his performance, this subject had the greatest number of baseline sessions (6).Through participating in this study, this subject did significantly decrease the total time and time to peak clorsiflexion for STS. He gradually required less frequent support in standing, and did not reposition his feet or take multiple attempts to stand as often, although he did continue to use the armrest for all STS attempts. Qualitative analysis of ankle kinematics also showed trends of improved consistency and greater similarity to a normal curve shape during the course of the study. Although the passive ankle flexibility was maintained at the 2-week follow up session, none of the other improvements were retained. Because improvements in STS were noted during the baseline sessions before the intervention was introduced, this indicates that perhaps the repeated practice provided as part of the measurement procedures may have been beneficial for this individual subject's STS performance. Furthermore, without the continued task practice during the 2-week follow-up period, those changes in STS performance were not maintained.

Subject B initially had a STS time similar to people with hemiplegia who are able to stand without armrests33,34 during the baseline sessions and demonstrated an increase in time due to the onset of acute low back pain in the middle of the study. On the ankle kinematic graphs, improvements in decreased time, earlier peak dorsiflexion, and improved consistency were noted between the 2 baseline sessions, indicating a benefit of practice. However, at the final intervention session, while the subject was still experiencing back pain, increased time and later peak dorsiflexion was noted, along with increased reliance on the armrest. It is possible that Subject B did not demonstrate improvements in the intervention phase because the movement strategy was altered secondary to low back pain. Unlike Subject A, improvement in ankle kinematics was noted at the 2-week follow up session in comparison to the last intervention session, and his back pain had resolved at this point.

The average time to perform STS for Subject C in the baseline sessions was comparable to times reported in the literature for healthy elderly.26 No change in time was noted during the baseline or intervention sessions, which may have reflected the fact that this subject was already performing the task at a relatively fast speed. The shape of the ankle kinematic curve for Subjects C and E were very similar to the curve for the healthy subject even in the initial baseline sessions. This indicates that they may have already demonstrated an efficient movement strategy at the ankle prior to participating in the study, although both of these subjects were able to decrease their reliance on the armrest.

Subject D demonstrated a STS time consistent with the subjects following stroke who had not fallen.50 Improved consistency in ankle kinematics was noted between the 2 baseline sessions and the last intervention session, along with decreased reliance on the armrest and less frequent foot repositioning. The trend of improved consistency between trials continued to improve in the follow up session, indicating that the movement strategy may have been retained, unlike Subject A.

Although there was no consistent pattern of improvement in peak-to-peak ankle excursion or STS time for the subjects, the kinematic graphs appear to show changes in how the ankle moved during the task. Specifically, Subjects A and D show clear patterns of improved consistency in ankle patterns during the course of the study, independent of the intervention. Subject D retained this consistency after 2 weeks without intervention, and Subject A did not. Perhaps the quantitative measures of STS time and peak-to-peak ankle excursion were too global to pick up on these subtle changes in strategy.

There were several limitations in the design and methodology of this study that may have influenced the findings. Investigator bias may have been present because all the measurements and interventions were performed by the primary investigator of this study.The choice of a single subject design was supported by the variability of subject characteristics and their response to the intervention and repeated practice. However, generalixability is extremely limited with such a small number of subjects. There is also a significant practice effect when using a repeated measures design, which may have influenced the STS performance of the subjects in this study.

The subjects who participated in this study were younger (mean 62.8 years) than many of the people who have a stroke, and the subjects all sustained the CVA less than 11 months prior to participation in this study. Decreased connective tissue extensibility is associated with aging and prolonged immobility, so these subjects may have had a better response to the intervention than older subjects or people with chronic CVA. However, these subjects were all more than 7 months post-CVA, and it was assumed that their impairments would not change without intervention at this point.

Passive ankle ROM is only one of many impairments that may have had an impact on STS function in these subjects. Use of newly gained ankle mobility may have been hindered by an inability to activate muscles, incoordination of muscles, or hypertonicity, among other impairments.The instructions given to the patient regarding foot placement appeared to be insufficient to teach the subject how to change their strategy to fully use the new ankle motion. Future research should incorporate an additional intervention to specifically encourage the patient to use the new ankle mobility, such as biofeedback regarding muscle activation or ankle position, manual guidance, active ankle exercises, or functional task practice.

Larger studies with randomly assigned control groups would improve the ability to generalize these findings to a larger population. Evaluation of knee and hip motions on the hemiparetic limb, as well as kinematics of the opposing limb, would provide a comprehensive view of the linked system and capture any compensations for ankle mobility limitations in the hemiplegic limb. People with hemiplegia tend to distribute their weight asymmetrically, and it would have been helpful to be able to assess any changes that occur in this through forceplate analysis.

Although the subjects in this study did not appear to use the gains in ankle motion for the STS task, they reported anecdotally that their function improved. Future studies should include analysis of other functional activities or a health status questionnaire to capture changes in overall quality of life that may occur from participating in the study.

SUMMARY

The primary finding of this study was that joint mobilizations were effective in improving passive ankle joint ROM in 5 subjects with chronic hemiparesis following a CVA, although there did not appear to be a direct relationship between improved ankle mobility and sit-to-stand function.

ACKNOWLEDGEMENTS

The authors would like to acknowledge and thank their colleagues in the MPT program of UMDNJ and Rutgers University for their support and use of lab space for this study, as well as Diana Glendinning, PT, PhD and MaryAnn Clark, PT, EdD of Seton Hall University for their efforts in guiding the development of this project.

REFERENCES

1 Yarkony GM, Sahgal V. Contractures: A major complication of craniocerebral trauma. Clin Orthop. 1987;219:93-96.

2 Given JD, Dewald JP, Rymer WZ. Joint dependent passive stiffness in paretic and contralateral limbs of spastic patients with hemiparetic stroke. J Nenrol Neurosurg Psychiatry. 1995;59:271-279.

3 Gottlieb GL, Agarwal GC, Penn R. Sinusoidal oscillation of the ankle as a means of evaluating the spastic patient. J Neural Neurosurg Psychiatry. 1978;41:32-39.

4 Sinkjaer I, Magnussen I. Passive, intrinsic and reflexmediated stiffness in the ankle extensors of hemiparetic patients. Brain. 1994;117:355-363.

5 Harvey LA, Batty J, Crosbie J, Poulter S, Herbert RD. A randomized trial assessing the effects of 4 weeks of daily stretching on ankle mobility in patients with spinal cord injuries. Arch Phys Med Rehabil. 2000;81:1340-1347.

6 Davies PM. Steps to Follow. New York, NY: Springer-Verlag; 1985.

7 Ryerson SD. The foot in hemiplegia. In: Hunt G, ed. Physical Therapy of the Foot and Ankle. New York, NY: Churchill-Livingstone; 1988:109-131.

8 Thilmann AF, Fellows SJ, Ross HF. Biomechanical changes at the ankle joint after stroke. J Neurol Neurosurg Psychiatry. 1991;54:134-139.

9 Hufschmidt A, Mauritz K-H. Chronic transformation of muscle in spasticity: A peripheral contribution to increased tone. J Neurol Neurosurg Psychiatry. 1985;48:676-685.

10 O'Dwyer NJ, Ada I, Nielson PD. Spasticity and muscle contraction following stroke. Brain. 1996;119:1737-1749.

11 Amiel D, Woo SL-Y, Harwood FL, Akeson WH. The effect of immobilization on collagen turnover in connective tissue: a biochemical-biomechanical correlation. Acta Orthop Scand. 1982;53:325-332.

12 Akeson WH, Amiel D, Abel MF, Garfin SR, Woo SL-Y. Effects of immobilization on joints. Clin Orthop. 1987;219:28-87.

13 Walker JM, Sue D, Miles-Elkousy N, Ford G, Trevelyan H. Active mobility of the extremities in older subjects. Phys Ther. 1984;64:919-923.

14 James B, Parker AW.Active and passive mobility of lower limb joints in elderly men and women. Am J Phys Med Rehabil. 1989;68:162-167.

15 Gajdosik RL, Vander Linden DW, Williams AK. Influence of age on length and passive elastic stiffness characteristics of the calf muscle-tendon unit of women. Phys Ther. 1999;79:827-838.

16 Gillette PD, Fell RD. Passive tension in rat hindlimb during suspension unloading and recovery: Muscle/joint contributions. J Physiol. 1996;81:724-730.

17 American Physical Therapy Association. Guide to physical therapist practice. 2nd ed. Phys Ther. 2001;81:9-744.

18 Kaltenborn FM. Manual Mobilization of the Joints: The Kaltenborn Method of Joint Examination and Treatment. 5th ed. Oslo, Norway: Olaf Norlis Bokhandel; 1999.

19 Cochrane CG. Joint mobilization principles: Considerations for use in the child with central nervous system dysfunction. Phys Ther. 1987;67:1105-1109.

20 Harris SR, Lundgren BD. Joint mobilizations for children with central nervous system disorders: Indications and precautions. Phys Ther. 1991;71:890-896.

21 Dijs HM, Roofthooft JMA, Driessens MF, De Bock PGE, Jacobs C, Van Acker KL. Effect of physical therapy on limited joint mobility in the diabetic foot: A pilot study. J Am Podiatr Mea Assoc. 2000;90:126-132.

22 Green T, Refshauge K, Crosbie J, Adams R.A randomized controlled trial of a passive accessory joint mobilization on acute ankle inversion sprains. Phys Ther. 2001;81:984-994.

23 Schenkman M, Berger RA, O Riley PO, Mann RW, Hodge WA. Whole-body movements during rising to standing from sitting. Phys Ther. 1990;70:638-650.

24 Shepherd RB, Koh HP. Some biomechanical consequences of varying foot placement in sit-to-stand in young women. Scand J Rehabil Med. 1996;28:79-88.

25 Stevens C, Bojsen-Maller F, Soames RW. The influence of initial posture on the sit to stand movement. Eur J Appl Physiol. 1989;58:687-692.

26 VanderLinden DW, Brunt D, McCullock M. Variant and invariant characteristics of the sit-to-stand task in healthy elderly adults. Arch Phys Med Rehabil. 1994;75:653-660.

27 Khemlani MM, Carr J, Crosbie WJ. Muscle synergies and joint linkages in sit-to-stand under two initial foot positions. Clin Biomech. 1999;14:236-246.

28 Janssen WGM, Bussmann HBJ, Stam HJ. Determinants of the sit-to-stand movement: A review. Phys Ther. 2002;82:866-879.

29 Ikeda ER, Schenkman ML, O Riley PO, Hodge WA. Influence of age on dynamics of rising from a chair. Phys Ther. 1991;71:473-481.

30 Cheng P, Liaw M, Wong M, Tang F, Lee M, Lin P.The sit to stand movement in stroke patients and its correlation with falling. Arcb Phys Med Rehabil. 1998;79:1043-1046.

31 Engardt M, Olsson E. Body weight while rising and sitting down in patients with stroke. Scand J Rehabil Med. 1992;24:67-74.

32 Engardt M, Ribbe T, Olsson E. Vertical ground reaction force feedback to enhance stroke patients' symmetrical body weight distribution while rising / sitting down. Scand J Rehabil Med. 1993;25:41-48.

33 Hesse S, Schauer M, Malezic M, Jahnke M, Mauritz K. Quantitative analysis of rising from a chair in healthy and hemiparetic subjects. Scand J Rehabil Med. 1994-26:161-166.

34 Hesse S, Schauer M, Peterson M, Jahnke M. Sit-to-stand manoeuvre in hemiparetic patients before and after a 4-week rehabilitation programme. Scand J Rehabil Med. 1998;30:81-86.

35 Ada L, Westwood P A kinematic analysis of recovery of the ability to stand up following stroke. Aust J Physiother. 1992;38:135-142.

36 Yoshida K, Iwakura H, Inoue F. Motion analysis in the movements of standing up and sitting down from a chair. Scand J Rehabil Med. 1983;15:133-140.

37 Lee MY, Wong MK, Tang F, Cheng P, Lin PS. Comparison of balance responses and motor patterns during sit-to-stand task with functional mobility in stroke patients. Am J Phys Med Rehabil. 1997;76:401-410.

38 Milne AD, Chess DG, Johnson JA, King GJW. Accuracy of an electromagnetic tracking device: A study of the optimal operating range and metal interference. J Biomech. 1996;29:791-793.

39 Riess J, Abbas JJ. Evaluation of FNS control systems: Software development and sensor characterization. Biomed Sci Instrum. 1997;33:197-202.

40 Meskers CGM, Fraterman H, van der Helm FCT, Vermeulen HM, Rozing PM. Calibration of the "Flock of Birds" electromagnetic tracking device and its application in shoulder motion studies. J Biomech. 1999;32:629-633.

41 Stokdijk M, Biegstraaten M, Ormel W de Boer YA, Veeger HEJ, Rozing PM. Determining the optimal flexion-extension axis of the elbow in vivo:A study of interobserver and intraobserver reliability. J Biomech. 2000;33:1139-1145.

42 Umberger BR, Nawoczenski DA, Baumhauer JF. Reliability and validity of first metatarsophalangeal joint orientation measured with an electromagnetic tracking device. Clin Biomech. 1999;14:74-76.

43 Slobounov SM, Simon RE, Bush JA, Kraemer WJ, Sebastianelli W, Slobounova E. An alternate method of range of motion measurement. J Strength Cond Res. 1999;13:389-393.

44 Portney LG, Watkins MP. Foundations of Clinical Research: Applications to Practice. 2nd ed. Upper Saddle River, NJ: Prentice Hall Health; 2000.

45 Nourbakhsh MR, Ottenbacher KJ. The statistical analysis of single-subject data: A comparative examination. Phys Ther. 1994;74:768-776.

46 Ottenbacher KJ. Evaluating Clinical Change: Strategies for Occupational and Physical Therapists. Baltimore, Md: Wiliams & Wilkins; 1986.

47 Ottenbacher KJ, Hinderer SR. Evidence-based practice: Methods to evaluate individual patient improvement. Am J Phys Med Rehabil. 2001;80:786-796.

48 Tryon WW. A simplified time-series analysis for evaluating treatment interventions. J Appl Behav Anal. 1982;15:423-29.

49 Blumberg CJ. Comments on "A simplified time-series analysis for evaluating treatment interventions." J Appl Behav Anal. 1984;17:539-542.

50 Kralj A, Jaaeger RJ, Munih M. Analysis of standing up and sitting down in humans: Definitions and normative data presentation. J Biomech. 1990;23:1123-1138.

51 Wu,G.A review of body segmental displacement, velocity, and acceleration in human gait. In: Craik RL, Oatis CA, eds. Gait Analysis: Theory and Application. St. Louis, Mo: Mosby; 1995:205-222.

52 Andriacchi TP, Andersson GB, Fermier RW, Stern D, Galante JO. A study of lower-limb mechanics during stair climbing. J Bone Joint Surg. 1980;62:749-757.

53 Arnadottir SA, Mercer VS. Effects of footwear on measurements of balance and gait in women between the ages of 65 and 93 years. Phys Ther. 2000;80:17-27.

54 Hughes MA, Schenkman M. Chair rise strategy in the functionally impaired elderly. J Rehabil Res Dev. 1996;33:409-412.

55 Hughes MA, Weiner DK, Schenkman M, Long RM, Studenski SA. Chair rise strategies in the elderly. Clin Biomech. 1994;9:187-192.

Patricia Kluding, PhD, PT,1 Genevieve Pinto Zipp, EdD, PT2

1 Assistant Professor, Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, KS (pkluding@kumc.edu)

2 Associate Professor, School of Graduate Medical Education, Seton Hall University, South Orange, NJ

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