Purpose: Shoulder immobilization devices are commonly used in the treatment of older adults following proximal humeral fractures. Immobilization of the shoulder may have a negative effect on balance, which could increase risk for falls. The purpose of this study was to examine the effect of shoulder immobilization on balance in the community-dwelling older adult population as measured by the Berg Balance Scale (BBS).
Methods: Fifty-three subjects (14 men and 39 women, mean age = 75.4 years) participated in the study. The BBS was administered twice to each participant. Subjects were tested once while wearing a shoulder immobilizer and once without a shoulder immobilizer. The immobilizer positioned the elbow at 90° of flexion and anchored the arm to the trunk. The Wilcoxon signed-ranks test was used to evaluate differences in BBS scores. A 2-tailed test was performed with α set at .05.
Results: Mean (SD) BBS scores were 53 (4.0) without the immobilizer and 52 (4.7) with the immobilizer. BBS change scores (score with immobilizer minus score without immobilizer) ranged from +1 to −7, with a mean change score of −1.02. The Wilcoxon signed-ranks test indicated a significant difference between paired observations (negative ranks = 29, positive ranks = 6, P < .0001). Balance was impaired (significantly lower BBS scores) when subjects wore the device compared with the testing sessions without the device.
Conclusions: The results indicate that immobilizing the shoulder may have a negative effect on balance as measured by the BBS. If shoulder immobilization places an individual at greater risk for falls, early balance screening by a physical therapist to determine the appropriateness of a fall prevention program may be indicated
Fractures of the proximal humerus are the third most common fracture in older adults and may account for 10% of all fractures in the Medicare population.1 These fractures increase exponentially with age and occur more frequently in white women older than 50 years.2–6 Proximal humeral fractures tend to occur in less active women with low bone mineral density and poor neuromuscular function4,7,8 and have been associated with low-dietary calcium, history of previous falls, depression, difficulty walking in dim light, left-handedness, and the use of hearing aids.4,5 Shoulder fractures in the older adult population may result in serious medical and socioeconomic consequences,6 including an increase in morbidity and mortality.9,10
More than 90% of proximal humerus fractures are attributed to moderate trauma, generally a fall from a standing height onto a hard surface.11 The injury occurs most frequently in individuals who walk slowly, fall sideways or obliquely forward, and are not able to slow or break the fall with an outstretched arm.11,12 Some period of shoulder immobilization is traditionally involved in managing these patients to decrease pain and stabilize the fracture site.13–15 Immobilization may be achieved by using a sling or strapping system that anchors the arm to the trunk. Individuals with fracture usually ambulate and perform activities of daily living while wearing shoulder immobilizers and are generally not seen by a physical therapist until range-of-motion exercises are deemed appropriate.
Little is known about the impact of various orthopedic positioning devices on an individual's mobility or postural stability. Response of trunk movements to combined roll and pitch perturbations are significantly altered in older adults,16 and compensatory arm movements play an important role in maintaining balance with even small perturbations.17 Immobilizing the upper extremity restricts movements of the trunk and upper limb and may interfere with balance strategies and movement patterns. The purpose of this study was to examine the effect of shoulder immobilization on balance, as measured by the Berg Balance Scale (BBS), in the community-dwelling older adult population.
Participants in this research study were recruited by word of mouth and from advertisements posted in area churches. Men and women of any race or ethnic background who were 65 years or older, English speaking, able to follow directions, and living independently in the community were eligible to participate. Subjects were excluded if they had a history of stroke, transient ischemic attack, Parkinson disease, or lower extremity joint replacement. Subjects were also excluded if they had an upper extremity immobilized within 1 month before testing. Eligible participants read and signed an informed consent outlining the procedures, benefits, and risks of participating in the study. The study design and methodology were approved by the principal investigator's institutional review board.
Balance was assessed using the BBS, which is considered a reliable and valid tool for assessing functional balance in older adults.18–22 The BBS consists of a series of 14 functional tasks that are scored on a 5-point ordinal scale ranging from 0 (cannot perform) to 4 (safe and independent). The maximum score on the BBS is 56, with higher scores indicating better balance. A total score above 45 is associated with a decreased likelihood of falling.21
Subjects were tested at a university-affiliated physical therapy clinic or in the recreation hall of local churches. The BBS was administered by 4 second-year physical therapy students who had been trained by the principal investigator (AC), a physical therapist with more than 20 years of clinical experience. Before testing study subjects, students reviewed the instructions for administering the BBS with the principal investigator. The students then administered the test on the principal investigator and discussed any concerns during the testing. The BBS was administered twice to each study participant by the same examiner, with a 2-minute rest between trials. Subjects were tested once while wearing a shoulder immobilizer and once without the immobilizer; the order of testing was determined by random assignment. The immobilizer positioned the elbow at 90° of flexion, anchored the arm to the trunk, and was fitted on the side of the dominant hand (Figure 1). The total BBS score was recorded for both trials.
Descriptive statistics were used to describe subject characteristics and BBS score distributions. The Wilcoxon signed-ranks test was used to evaluate the differences in balance scores in subjects who performed BBS activities under 2 conditions: with a shoulder immobilizer and without an immobilizer. A 2-tailed test was performed with α set at .05. This nonparametric test was chosen because the BBS provides ordinal data, and parametric assumptions of population normality and homogeneity of variance were not satisfied. The GB-STAT Version 6.5.6 Pro Macintosh (Dynamic Microsystems, Inc., Silver Springs, MD) statistical program was used to perform all statistical analyses.
Fifty-four non-Hispanic white people were screened, and 53 were eligible to participate in this study. All 53 subjects completed both trials (with and without a shoulder immobilizer) of BBS testing. The majority of subjects were female (74%) and had not fallen during the previous 6 months (72%). Table 1 provides baseline characteristics of subjects. The distribution of BBS scores for the 2 testing conditions is presented in Table 2. The change scores (score with immobilizer minus score without immobilizer) ranged from +1 to −7, with a mean change score of −1.02. A negative change score indicates lower BBS scores when participants were wearing immobilizers.
Thirty-five of the 53 subjects demonstrated differences in BBS scores between the first and second trials: 29 scored lower on the BBS while wearing the shoulder immobilizer, whereas only 6 scored lower on the BBS without the immobilizer. The Wilcoxon signed-ranks test (Table 3) indicated a significant difference between paired observations (z = −4.177, P < .0001).
Eighteen of the 53 subjects (34%) exhibited no difference in scores (ie, the use of an immobilizer did not adversely affect balance), and 9 of these 18 subjects (50%) achieved the highest possible score (56) during both test conditions. Balance may have been affected in these 9 individuals, but the BBS may have failed to detect any changes because of a ceiling effect. In examining characteristics of these 9 individuals, the mean age was 70.9 (range, 66-79) years, 6 of 9 were women, and 1 of 9 had fallen within the past 6 months. In general, this group of 9 was younger than the total group (mean age = 70.9 vs 75.4), had fewer women (67% vs 74%), and had fewer falls (11% vs 26%).
When comparing participants with history of falls (n = 14) with participants with no history of falls (n = 38), the mean (SD) change scores were similar for the 2 groups: −0.93 (1.2) for the participants with history of falls and −1.05 (1.7) for the participants with no history of falls. Of the 53 subjects, 33 wore shoulder immobilizers during the first trial and 20 wore immobilizers during the second trial. Of the 20 subjects who wore the immobilizer during the second trial, scores increased for 15% (3/20), decreased for 50% (10/20), and stayed the same for 35% (7/20). Of the 33 subjects who wore the immobilizer during the first trial, scores increased for 55% (18/33), decreased for 12% (4/33), and stayed the same for 33% (11/33).
In this study, we found a statistically significant difference in balance scores when older, community-dwelling adults wore shoulder immobilizers. Balance was impaired (significantly lower BBS scores) when subjects wore the device compared with the testing sessions without the device. Although we found statistical significance, a mean change score of −1.02 may not represent a clinically significant change because we did not determine the minimal detectable change (MDC), which is the minimal change in a test score that is not a result of measurement error.23 Steffen and Seney23 calculated MDC95 (95% confidence interval) for studies that reported reliability values for the BBS and provided the following: MDC = 2 for 26 subjects with Parkinson disease; MDC = 5 for 24 older adults (with or without cerebrovascular accident); MDC = 3 for 20 people with hemiparesis; MDC = 4 for 5 people with traumatic brain injury; and MDC = 5 for 37 community-dwelling adults with parkinsonism. Steffen and Seney23 determined these values for subjects with neurologic disorders and found variability within diagnostic categories (eg, MDC values for subjects with Parkinson disease were 2 in 1 study and 5 in another). Minimal detectable change in BBS scores has not been determined for subjects without neurologic disorders (eg, our study population) or in patients with orthopedic conditions (eg, proximal humeral fractures). However, because our change scores ranged from +1 to −7, some of these scores may represent measurement error.
We did not conduct a reliability trial prior to the study to determine reliability of our raters; however, others have found good to excellent interrater reliability for the BBS.18,20,21,24 As in our study, Holbein-Jenny et al20 also used student physical therapists as raters in a study assessing balance in older adults and reported good interrater reliability (ICC = 0.88).
We attempted to control for order of testing through random assignment, but we did not have equivalent numbers of subjects for the 2 trials: 33 wore shoulder immobilizers during the first trial and 20 wore immobilizers during the second trial. We were concerned that there might be a learning effect and that participants would perform better on the second trial regardless of the use of shoulder immobilizers. While we recommend that future researchers attempt to control for order of testing, we believe that any learning effects between the first and second trials in our study were minimal.
We did not conduct a power analysis a priori because there is limited information on power analysis for nonparametric testing.25 In fact, Portney and Watkins26 state that power analysis with nonparametric testing is not necessary when significant differences are found and the null hypothesis is rejected.
We chose to use the BBS because it requires minimal equipment (a stopwatch, step, 2 chairs, and a ruler), can be administered in less than 20 minutes, and can be performed in a clinical or nonclinical setting. It was initially tested on an older adult population with documented balance impairments18 but has been used to assess balance in patients with stroke24 and with residents of personal care homes20 to determine if functional balance is associated with falls in older persons with history of hip fracture,27 to predict falls in older persons,21 and to screen inner-city community-dwelling older adults.28 One concern with BBS testing is rater bias. We were unable to blind raters to testing condition; therefore, rater bias may have occurred because the same tester took both measurements. Raters may have been influenced to score subjects lower on the BBS when wearing the immobilizer because of a preconception that balance might be worse under this condition.
Although we did not restrict participation in our study on the basis of race and gender, our sample was limited to non-Hispanic white, predominantly female, and older adults. This group of individuals may not reflect the general characteristics of all community-dwelling, older adults. Therefore, we cannot generalize the results of our study.
Future studies examining the effects of upper extremity immobilization on balance may want to consider using different performance-based assessment tools such as the Timed Up and Go or the Four Square Step Test that provide interval-level data and do not have issues with floor and ceiling effects. Including outcome measures of postural sway under different task conditions might provide a more comprehensive assessment of balance. In addition, it might be valuable to examine the effect of shoulder immobilization on temporal and spatial aspects of gait. Other researchers may also consider using a randomized block design to control for order of testing and to minimize any potential learning effects. Finally, a prestudy reliability trial would ensure tester reliability and determine MDC values to distinguish between measurement error and clinically significant changes.
Shoulder immobilization devices are commonly used in the treatment of older adults following proximal humeral fractures. However, the results of our study suggest that immobilizing the shoulder of some older adults may have a negative effect on balance as measured by the BBS. Patients who sustain proximal humeral fractures are usually not referred for physical therapy services until the fracture site is considered stable and range-of-motion exercises are indicated. If shoulder immobilization places an individual at greater risk for falls because of its impact on balance, early balance screening by a physical therapist to determine the appropriateness of a fall prevention program may be indicated.
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balance; proximal humeral fracture; shoulder immobilization