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The Effect of Wrist Position on Upper Extremity Function While Wearing a Wrist Immobilizing Splint

Gillen, Glen EdD, OTR, FAOTA; Goldberg, Rachel MS, OT; Muller, Sarit MS, OT; Straus, Juliana MS, OT

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JPO Journal of Prosthetics and Orthotics: January 2008 - Volume 20 - Issue 1 - p 19-23
doi: 10.1097/JPO.0b013e31815f013f
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Splints are commonly prescribed devices added to a person's body to support, align, immobilize, prevent or correct deformities, assist weak tendon-muscle units, or improve function.1 Wrist extension splints are commonly used to treat a variety of pathologies including cumulative trauma disorders, arthritis, fractures, neurologic based weakness secondary to stroke, sprain, strain, tendonitis, etc.1,2 Although this is a commonly used therapeutic device, the optimal immobilizing wrist position that would allow for maximum functioning is not clear and debated in the literature. It is typically suggested to angle the wrist in the range of 0° to 30° of extension when customizing a wrist splint. Specifically, 10° to 30° of wrist extension is typically suggested to maximize daily function1–3 although there is little empirical evidence to support this recommendation or to guide clinicians in choosing a specific wrist angle to maximize daily function. This study will begin to clarify this issue by examining the effect of various wrist positions on upper extremity function in healthy adults wearing wrist immobilizing splints.

Although the effect of the typically recommended range of wrist angles on upper extremity daily function has not been directly examined in the published research literature, several articles have examined the use of wrist extension splints in general and the effects on function. The following paragraphs will summarize these findings.

Fong and Ng4 tested the between-day repeatability and effect of wrist positioning on grip strength measurement. Examining 30 healthy men(ages ranging from 20 to 69 years of age), subjects were tested twice, 1 week apart, in six wrist positions. The authors documented significant differences in grip strength among the six wrist positions, with grip strength measured at 15° or 30° of wrist extension and 0° ulnar deviation significantly greater than that of 0° ulnar deviation and 0° extension or 15° ulnar deviation with or without extension.

Adams et al.5 aimed to quantify and compare the disabilities caused by reduced and absent wrist motion using objective measurements of task performance and perceived disability, and to assess the compensatory motions of the shoulder, elbow, forearm, and trunk caused by impaired wrist motion. The authors examined the wrist function of 21 normal subjects under conditions of reduced (30° flexion and 30° extension) and nearly absent wrist motion using established physical tests and questionnaires. The authors found that the average times to perform the Jebsen Taylor Hand Function Test and observed activities of daily living increased for both motion-restricted conditions of the wrist but did not differ significantly between the conditions. In addition, questionnaire scores regarding function were significantly worse for both motion-restricted conditions and poorest for nearly absent motion. The authors also noted that average compensatory motions in the extremity and trunk statistically increased for both motion-restricted conditions but were not marked and did not differ between the conditions. They concluded that perceived disability from reduced wrist motion appeared greater than measured functional loss using common physical tests and outcome surveys. Similarly, Carlson and Trombly6 examined the effect of wrist motion on the time required to complete the Jebsen Taylor Hand Function Test. The test was performed with the wrist free and with the wrist immobilized by a commercially available splint. The results showed a statistically significant increase in time to perform the tasks during immobilization when compared with the free condition. In addition to increased time required to perform tasks, wrist extension splints have been found to interfere with the quality of upper-extremity movement and result in requiring more range of shoulder movement compared to the free hand.7

Pagnotta et al.8 aimed to determine the effect of a wrist splint on work performance, hand dexterity, and pain during task performance, by examining 40 individuals with rheumatoid arthritis. Each patient was fitted with a commercially available wrist splint. Dexterity was measured with and without the splint using the Jebsen Taylor Hand Function Test and work performance was assessed using 2 tasks (one simulating the use of shears, the other the use of a screwdriver) on a work simulator. The tasks were performed both with and without the splint. The authors found that although the screwdriver task work performance was less with the splint, on the shears task, there was no significant difference in work performance with and without the splint. In addition, the average pain after performing both tasks was significantly less with the splint on. Similar to the above-cited findings, the average time to complete all seven tasks on the Jebsen Hand Function Test was longer when the subjects wore the splint compared with when they did not.

Stern9 examined the effects five styles of commercial static wrist extensor splints on 23 right-hand-dominant women without upper extremity dysfunction to determine whether any style, or styles, afforded better power grip strength, or finger dexterity as measured by the Purdue Pegboard. Four of the study splints afforded finger dexterity that did not differ significantly from that of the free hand while the fifth slowed finger speed. Although one of the splints permitted a power grip that was not significantly different from the free hand, the other four reduced grip strength. The author concluded that the five styles of commercial splints affect power grip and finger dexterity differently.

Previous research has found that applying a splint that positions the wrist in extension may or may not affect grip strength,4,9 scores on standardized measures of upper extremity may be negatively impacted6,8 and the wearer of the splint may perceive increased disability.5 In addition, wearing this type of splint has been found to result in increased use of compensatory proximal joint movements.7 Despite the negative effects, wearing this type of splint may be medically necessary to reduce symptoms of pathology.10,11 Although a range (0° to 30°) of wrist extension is typically suggested related to choosing and fabricating splints, there is little empirical research to help clinicians decide which particular angle supports or constrains upper extremity function. The purpose of this study is to begin to provide empirical evidence exploring the effect that various wrist positions have on upper extremity function.

In summary, the wrist is thought to be “the key to ultimate hand function.” As wrist splints are commonly prescribed it is essential “to determine the position in which a joint is to be supported relative to hand dominance and task requirements because specific functional demands vary greatly ....”1(p.437) This research aims to guide to clinicians in their clinical reasoning related to understanding how wrist angle impacts upper extremity when wearing various splints.

SUBJECTS AND METHODS

This descriptive study aimed to examine the effects of various splinted wrist positions on aspects of upper extremity function, such as speed and accuracy of movement. This study was approved by the institutional review board at the university at which it took place and informed consent was obtained from all subjects.

A sample of convenience was recruited through person-to-person contact at a large private urban university. The sample was delimited to individuals that were between the ages of 18 and 65 years and who did not present with any upper extremity pathology that interfered with activities of daily living as per self-report.

The Jebsen Taylor Hand Function Test was utilized to objectively measure upper extremity function. It is a timed test used to measure hand and arm function, a cornerstone of a person's functional abilities. It evaluates function or dysfunction via the timed performance of simulated activities of daily living.12 The test consists of seven subtests including writing, page turning, picking up small familiar objects, stacking checkers, simulated eating, lifting empty cans, and lifting heavy cans. The test is administered using both the nondominant and dominant hands. It has been found to be both valid and reliable. The test retest reliability coefficients range from 0.60 to 0.99. Each subtest of the Jebsen Taylor Hand Function Test has been shown to be reliable when evaluated in test retest situations. Additionally, the effects of practice were found to be insignificant.12 Stern13 confirmed the test retest reliability to be adequate, with a range from r = 0.67 to r = 0.99. Before administering the Jebsen Taylor Hand Function Test, inter-rater reliability was established between the test administrators.

The test was administered in a quiet room free of distraction. The subtests required strict measurements for test administration; therefore, measurements were taken on the testing surface before testing and marked with masking tape to ensure accurate and standardized testing. The test was administered three consecutives times. Each time the subject wore a commercially available wrist extension splint (Rolyan® AlignRite™ Wrist Support) that positioned the wrist in 0° (neutral), 15°, or 30° of wrist extension. Wrist angles were confirmed via goniometry. The splint used in this study supports the wrist while allowing the digits and thumb free movement. It is made of woven cotton-coated rubber fabric with an open weave and had an adjustable metal stay. The splint covers approximately two-thirds of the forearm and includes a wrap around strap for extra support. The appropriate size splint was determined via measurement of wrist circumference as per manufacturer's recommendation. The order in which the wrist angles were tested was randomized to control for fatigue and practice effects by having each participant choose two cards from a pile of three. Each card had a different wrist position printed on it, and the order of testing was determined by the position chosen first, second, and third.

In terms of data analysis, the intraclass coefficient (ICC) was calculated to determine inter-rater reliability. An analysis of variance (ANOVA) for repeated measures to detect within-subject changes was performed to determine differences between the three wrist positions. The significant F ratios were subjected to a post hoc multiple comparison test with a Bonferroni adjustment to determine the differences between the specific wrist positions. The results were considered to be significant at the .05 level of confidence. Descriptive statistics were generated to describe the sample.

RESULTS

The sample consisted of 20 women ranging in age from 21 to 64, with a mean age of 27.5 (SD = 9.6). Participants identified themselves as white (n = 13), Asian (n = 2), Hispanic (n = 3), Indian (n = 1), and other ethnicity (n = 1). Sixteen participants were right-hand dominant and four participants were left-hand dominant.

In terms of inter-rater reliability, the ICC for this study was 0.99. The ANOVA for repeated measures revealed that significant findings were evident only for the dominant hand on two of the subtests of the Jebsen Test of Hand Function. Dominant hand performance during feeding with a neutral wrist was found to be significantly slower than when the wrist was positioned in 15° of extension (F = 4.292, p < 0.021). Stacking checkers with the dominant hand in 30° of wrist extension was significantly slower than stacking checkers with the dominant hand in the neutral wrist position (F = 3.070, p < 0.037). All findings related to nondominant hand function were not significant. See Table 1for a summary of scores obtained on the Jebsen Test of Hand Function.

T1-5
Table 1:
Results of the Jebsen Taylor Hand Function Test performed in three wrist positions (n = 20; measured in seconds)

DISCUSSION

The results of this study indicated that there was no significant difference between the tested wrist positions (0°, 15°, 30°) when using the nondominant hand to perform activities while wearing a wrist splint. However, significant differences were found when wearing various angled wrist splints to perform functional activities with the dominant hand albeit only for select tasks (feeding and stacking checkers). Although this study was descriptive in nature and did not aim to establish the cause of the findings, we hypothesize that only dominant hand performance was affected because the tasks included on the Jebsen Test of Hand Function are traditionally performed with dominant hand and are over-learned (such as, feeding). It is possible that established motor plans for the dominant hand are interrupted when the wrist is immobilized resulting in variable performance. As the tasks may be somewhat novel for the nondominant hand, these motor plans may not be as established perhaps explaining why little impact from the immobilization was noted.

During the feeding subtest, participants performed at a significantly faster rate when their dominant wrists were positioned in 15° of extension when compared with the performance with a neutral wrist. Although not significant, there was also a faster rate of performance when positioned in 30° of extension as compared to performance with a neutral wrist. During the stacking checkers subtest, participants performed at a significantly faster rate when their wrists were positioned in neutral when compared with when they were positioned in 30° of extension. Although not significant, subjects performed at a faster rate when their wrists were positioned in neutral when compared with when they were positioned in 15° of extension.

Overall, the differences found related to the three wrist positions were task specific. Although for the majority of the tasks there were no significant differences between the wrist positions specific tasks were in fact negatively impacted. The clinical implication of this finding is consistent with other author's recommendations that although medical needs and symptom control is the critical issue when determining the design of splints, it is also important to determine the daily living tasks that a person typically engages in to determine the most appropriate design.1–3,9 Although the overall assumption is that extension is the preferred position to optimize function, this study provides preliminary data that although this assumption may hold true for some daily activities such as feeding, other activities may be more efficient and functional in a wrist position that is closer to the neutral position.

When prescribing or fabricating a splint for a particular clinical presentation, decisions regarding the optimal position to immobilize the wrist should consider both symptom control from a medical perspective as well as lifestyle including the type and frequency of daily living tasks that are usually engaged in. It is recommended that a clinical evaluation for splinting include collecting data regarding a patient's usual routine of daily activities that require use of the wrist that may be splinted. Although some diagnoses such as stroke do not require stringent guidelines regarding a specified position for wrist immobilization when fabricating a splint,2 others such as carpal tunnel syndrome10 are in fact strict and do not allow as much clinical flexibility. Therefore, an additional clinical implication is to educate and provide practice in tasks that may be adversely impacted secondary to the necessary position of wrist immobilization.

Because only healthy and relatively young females were tested during this study, generalization of findings is difficult. In addition to documented gender related strength differences,14 gender differences can be observed in other aspects of motor tasks such as accuracy,15 which further may have influenced the results. In addition, the sample size was small which may have resulted in a type II error. Finally, the definition of upper extremity function was limited to performance on a specific timed test of simulated activities of daily living. Further research should include a larger sample size to increase the statistical power of the study. Additionally, future research should examine the quality of movement during the seven subtests and not just the speed of completing the task. It is also suggested that various clinical populations such as those presenting with Colles fracture, stroke, carpal tunnel syndrome, spinal cord injury, and Dequervain's syndrome be tested in the future.

REFERENCES

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Figure
Keywords:

wrist; splint; function

© 2008 American Academy of Orthotists & Prosthetists