American Academy of Orthotists & Prosthetists

Enhancing the Functional Envelope: A Review of Upper-Limb Prosthetic Treatment Modalities

Jayne Drummey

Abstract

The functional envelope involving the upper limb consists of multiple spheres of action that are integrated and determined by the shoulder complex, elbow, wrist, and hand.¹ Upper-limb motion is rapid, spatially complex, and has not received as much scientific attention as that of the three-dimensional kinematics of the lower limb. While assessing range of motion to determine the severity of disability in upper-limb-impaired patients is the current standard, this process usually involves measurement of range of motion in a single plane. Although this form of evaluation can provide valuable data, these measurements do not provide information on functional motion or how the limb moves during activities of daily living (ADL).

This paper explains what the functional envelope is and more importantly, it evaluates the literature on those treatment modalities, specifically in the realm of prosthetic intervention, that attempt to increase the functional envelope in patients with upper-limb amputations. From this explanation and evaluation, practitioners can draw more educated conclusions about which treatment options serve the patient best in increasing the functional envelope.

Introduction

While lower-limb movement analysis has been used since about 1900, analysis of the upper limbs is still considered to be at an early stage. In 2006, with a focus on biomechanics, Veeger and Pascoal compared motion-analysis references of lower-limb joints to those of upper-limb joints. They found that upper-limb references accounted for only 40 percent of the total, clearly illuminating the relative lack of biomechanical motion analysis of the upper limb.² The use of 3-D motion analysis in clinical application is said to be attributed to clinical gait analysis, a well-defined process of repetitive cyclic sequences that occur from heel strike to heel strike. Biomechanical models have been developed based on the movement of the lower limbs, which allow for calculation of joint angles, joint forces, and moments. In comparing gait analysis to upper-limb motion analysis, a number of problems have been revealed. These issues include, but are not limited to: (1) the variability of upper-limb movements when one or more movements is required for a specific task; (2) that the variability and complexity of tasks performed with the upper limb prevents the establishment of reliable and standardized procedures for measurement of the upper limb; (3) that the large range of movement increases the problem of skin movement, which reduces the accuracy of all measurement techniques; (4) that upper-limb motions cannot be described in two dimensions as can be accomplished in a lateral view of the gait cycle; and (5) that the assessment of external hand forces is difficult to achieve in most situations compared to what can be achieved in gait analysis with the use of force plates and footpressure soles.³

With such discrepancies, the variety, complexity, and range of upper-limb movements cannot be easily described and are an enormous challenge not only to assess and interpret quantitatively, but even more so to evaluate in clinical application. While assessing range of motion to determine severity of disability in affected patients is the current standard, this process usually involves measuring range of motion in a single plane. Although this form of evaluation can provide valuable data, these measurements do not provide information on functional motion or how the limb moves during activities of daily living (ADL). With these challenges, it is particularly difficult for healthcare providers to prescribe appropriate interventions based on what little information is known about the upper limb and the deficits affecting functionality due to disability.

Functional Upper-Limb Range of Motion

The upper limb is represented by a link-segment model composed of rigid segments with multiple degrees of freedom. Within the performance capacity of the upper limb, the most notable area of its abilities is the functional envelope. The functional envelope involving the upper limb consists of multiple spheres of action that are integrated and determined by the shoulder complex, elbow, wrist, and hand. Each of the pieces of the functional envelope refers to an area or areas of movement around an individual's body, which is based on the position of the limb segment in space. As one segment changes, it affects the functional envelope of the other segments and vice versa. In the past, researchers have studied this arc of motion in several different ways; however, research done specifically in the areas of functional range of motion during ADLs is an area of extreme importance to the individual with upper-limb disability.¹

In 2005, Magermans et al. examined the requirements for upper-limb motions during ADLs with a specific interest in normal movements of the shoulder. During this study, the shoulder and elbow motions of 24 healthy female subjects were measured with an electromagnetic tracking device while performing eight range-of-motion tasks and five ADLs. Activities in this study looked particularly at combing hair, perineal care, eating with a spoon, reaching, washing the axilla, and lifting a four-kilogram bag. The results in the hair-combing task indicated subjects used at least 73 degrees of glenohumeral elevation to comb their hair. Additionally, during arm elevation when combing hair, 20–100 degrees of glenohumeral elevation motion was observed along with large amounts of external rotation at the glenohumeral joint. In concurrence with previous studies, it was noted that elbow flexion is also very important in performing such a task, with minimal elbow flexion of 112 degrees used. In perineal care, the most important angle found for performing this task was axial rotation (internal rotation) of approximately 71 degrees. In the eating task, the most important joint angle found was elbow flexion (approximately 117 degrees) where the subject would not be able to bring the spoon to his or her mouth. The reaching task required the highest glenohumeral elevation (111 degrees), and grasp in the end phase of reaching required pronation of approximately 103 degrees. In the washing (axilla) task, 83 degrees of elevation and a minimum of 104 degrees of elbow flexion were required.⁴

In a study completed by Morrey et al. in 1981, normal patients were studied to obtain results for typical motion about the elbow. In this study, the amount of normal elbow motion required for 15 ADLs was recorded. In doing so, elbow flexion and forearm rotation (pronation and supination) were measured simultaneously by means of an electrogoniometer. The results are as follows: activities of dressing and hygiene required elbow positioning from about 140 degrees of flexion (which was needed to reach the occiput) to 15 degrees of flexion required to tie a shoe. Most of these activities were performed with the forearm in 0–50 degrees of supination. Other ADLs, such as eating, using a telephone, opening a door, and most other ADLs that were studied in this project were found to be accomplished with 100 degrees of elbow flexion (from 30–130 degrees) and 100 degrees of forearm rotation (50 degrees of pronation and 50 degrees of supination).⁵

In analyzing functional range of motion of the wrist, Ryu et al. similarly examined 40 normal subjects (20 men and 20 women) to determine the ideal range of motion required to perform ADLs. The amount of wrist flexion and extension, as well as radial and ulnar deviation, was measured simultaneously by means of a biaxial wrist electrogoniometer. The entire list of ADL tasks that were evaluated could be achieved with 60 degrees of extension, 54 degrees of flexion, 40 degrees of ulnar deviation, and 17 degrees of radial deviation, which reflects the maximum wrist motion required for daily activities.⁶

In a similar study performed in 1983 by Brumfield and Champoux, 19 normal adults were studied by a uniaxial electrogoniometer to determine the range of wrist motion required to accomplish 15 ADLs. These activities included many of the same activities noted in previous studies, such as cutting with a knife, bringing a fork to the mouth, using a telephone, bringing a glass to the mouth, etc. This study found that the optimum functional motion for the wrist to accomplish most activities is from 10 degrees of flexion to 35 degrees of extension. This was derived through observation and measurement determining range of motion during necessary activities, such as eating, drinking, using a telephone, and reading, which were accomplished with 5 degrees of flexion to 35 degrees of extension in addition to analysis of activities pertaining to personal care, which were found to be accomplished by motion of 10 degrees of wrist flexion to 15 degrees of wrist extension.⁷

Impaired Range of Motion

When range of motion is impaired, an individual's ability to perform ADLs often diminishes. Unfortunately, this kind of range of motion loss is a common consequence of many forms of upper-limb disability. In addition to the musculoskeletal functionally impaired patients whose limb segments still remain, there are also the upper-limb amputee patients who not only must functionally adjust to both the loss of joint function depending on the level of amputation but also functionally adjust to the complete loss of the limb segment, which diminishes spatial function. In the past, researchers have attempted to make functional comparisons between upper-limb deficiency and disability caused by upper-limb injuries other than amputation.

In 2004, Davidson made comparisons utilizing the Disability of the Arm, Shoulder, and Hand scale (DASH). The DASH scale asks about the patient's ability to perform 21 physical activities on a five-point Likert scale for degree of difficulty or severity. Activities include writing, food preparation, transportation, recreational needs, and changing a lightbulb overhead. Achieving a higher score on the DASH scale indicates a greater level of disability. Over a course of 48 months, 274 patients were given the DASH. There were 75 upper-limb amputees, 26 of whom had hand or digit amputations. The remaining 199 patients suffered from a variety of diagnoses including brachial plexus injury, complex regional pain syndrome, shoulder capsulitis, and carpal tunnel syndrome. The average DASH score for the cohort was 51/100. The highest average DASH scores were for bilateral amputations (68/100) and quadruple amputations (67/100). These populations had higher scores compared to brachial plexus injury, arthritis, and tendonitis, and scored the same as those patients with complex regional pain syndrome. Part of the DASH scale also looks at how individuals with different musculoskeletal disorders score when looking at activities of work and leisure. It was found that unilateral upper-limb amputees, partial-hand amputees, and amputees from brachial plexus injuries scored higher in their perceived disability during work tasks. These results are indicative of the fact that upper-limb amputees perceive themselves as having higher disability in work tasks than individuals with diagnoses such as brachial plexus injuries and complex regional pain syndrome; both of the latter groups scored lower than the amputee group.⁸

With such a large spectrum of disability and differences in diagnoses of their respective losses, healthcare professionals must spend a considerable amount of time selecting the appropriate intervention strategies to restore active and passive range of motion and, more importantly, to help patients regain their independence by enhancing functional performance in ADLs. The effectiveness of rehabilitation interventions in upper-limb impaired patients is not something frequently studied and has been somewhat subjective. While several studies have analyzed the use of different treatment modalities for these patients, results typically vary, and it is unknown whether these results truly help the patient gain functional independence because there is no "gold standard" for determining this value. Several prosthetic treatment modalities and their functional effectiveness in different types of upper-limb amputation have been studied and reported on over the last few decades. It is the hope that in trying to establish best treatment options functionally, healthcare professionals can make more educated recommendations to patients based on their specific needs and deficits.

Focus on the Individual with Upper-Limb Loss

When looking at the individual with upper-limb loss, several factors have been identified as possible limitations of functional outcome of treatment progress. Factors including interface design, suspension mechanisms, and prosthesis type, to name a few, all affect the functional envelope of the upperlimb amputee.

Interface Designs

In looking at interface design and suspension, there are a number of restrictions that directly affect certain levels of range of motion in the upper-limb amputee. Restrictions that are caused by prosthetic interfaces can often limit range of motion simply because of how they are designed. At the transradial level, self-suspending socket designs such as the Muenster and Northwestern styles have been shown to limit the amount of available active elbow flexion in some patients. A study done in 2003 by Miguelez, Lake, Conyers, and Zenie compared the range of motion in three different types of self-suspending interfaces as well as to the normal range of motion of the elbow. In normal elbow movement, range of motion from full extension to full flexion ranged from 0–146 degrees for a total arc of 146 degrees. With the application of the Muenster socket, functional arc of flexion was reduced to 78 degrees (ranging from 20–98 degrees), and with the use of the Northwestern socket, functional arc of flexion was reduced to 86 degrees (ranging from 12–98 degrees). In the same study, the use of the transradial anatomically contoured (TRAC) self-suspending interfaces was also studied to determine range of motion. This interface type uses aggressive contouring of bony anatomy and uses less-restrictive trimlines, which allows for better range of motion, among other benefits. When this interface underwent testing for range of motion comparisons, the more progressive TRAC had an elbow flexion arc of 100 degrees (ranging from 10–110 degrees)—a far better result than its predecessors' traditional interface designs.⁹

There are also potential problems with interface fit for the transhumeral amputees. A study was done by Bertels in 2001 which looked at shoulder motion both with and without the use of a prosthetic interface. Regardless of residual limb shape and interface type, there was an average decrease in shoulder range of motion by approximately 20 percent in each plane. With the use of traditional transhumeral interface designs, the shoulder cap was found to act as a mechanical stop, which forces limitations in anteversion/retroversion, abduction/adduction, and horizontal flexion/extension of the shoulder.¹⁰

In another study completed in 2000 by Daly, subjects with transradial amputations utilizing conventional supracondylar suspension mechanisms for use of a self-suspending prosthesis were compared to the use of roll-on liners. Daly looked at three transradial patients and found that there was increased elbow range of motion from 15–27 degrees in the silicone roll-on liner users.¹¹

Harnessing

In 2001, Bertels went on to look at the effect of conventional harness use on shoulder motion in transhumeral amputees. As previously thought, the harness was shown to restrict motion of the shoulder. It was found that in comparing the harnessed shoulder to the normal shoulder, the normal shoulder abducted and moved more proximally to a greater extent than that of the harnessed shoulder. The normal shoulder girdle usually abducts 170mm and moves proximally about 90mm, whereas the use of a harness restricts this amount to 95mm and 20mm, respectively. In comparing the two motions of the shoulder, normal and harnessed, there is a 44 percent reduction in normal abduction range of motion and a reduction of normal adduction range of motion of up to 78 percent. Positive results can only be achieved if the prosthetic interface and body harness are fitted according to the individual characteristics of the patient. This can be effective for understanding which motions and cable and harness positions are most suitable based on the patient's needs.¹⁰

Type of Prosthesis

A study completed in 1988 by Weaver, Lange, and Vogts made a comparison between myoelectric and conventional prostheses in adolescents with unilateral transradial congenital limb deficiency. One of the areas of this study looked at functional range of motion based on fit of the prosthesis. Four of the eight individuals who were using the myoelectric prosthesis, which suspended at the elbow and forearm utilizing the traditional Muenster-style socket design, had a decrease in active elbow flexion of 25 degrees; additionally, two subjects lost an average of 45 degrees of supination, while one subject gained 15 degrees of active pronation.¹²

Additional research has taken place in the functional effectiveness of body-powered prostheses versus externally powered prostheses in transradial amputees, which has provided significant findings. Referring to the previously mentioned 1988 study completed by Weaver, Lange, and Vogts, comparisons were made between myoelectric and conventional prostheses in adolescent amputees. In this particular study, points of interest covered were functional comparisons and bimanual assessment. Subjects were measured and fit with myoelectric below-elbow prostheses with a self-suspending interface and Otto Bock electric hand. All individuals had only used conventional body-powered prostheses prior to this study. As far as grasp, individuals felt they could grasp objects and hold them more securely with the myoelectric prosthesis because the grip force was greater. In the bimanual assessment, subjects performed 38 activities that were grouped into six ADL categories—dressing, hygiene, eating, tasks about the home, school/work activities, and play activities. Subjects rated their performance in each, initially with the body-powered prosthesis, and then again with the myoelectric prosthesis. In these tasks, it was found that bimanual function with the myoelectric prosthesis increased by 61.7 percent in the dressing task, 50 percent in hygiene, 51.8 percent in eating, 55.77 percent in tasks about the home, 79.48 percent in school and work activities, and 70.58 percent in play activities. The obvious increase in function in these subjects, which was also noted, was the freedom from harnessing, which allowed the subjects to have more accessibility within their functional envelope.¹²

A similar study, done by Stein and Walley in 1983, compared function of upper-limb amputees using myoelectric versus conventional prostheses. In this study, the function of each prosthesis was compared through the use of standardized tasks as well as to the use of the sound hand in the case of unilateral amputees. Thirty-six subjects were studied—20 with myoelectric prostheses and 16 with body-powered prostheses. To test functional range of motion, subjects were asked to open and close their terminal devices three times in five different positions: above shoulder level, at the mouth, behind the neck, behind the back, and in front of the body. The final score was based on the number of positions at which the amputee could reliably operate the prosthesis. In addition to this, amputees were asked to perform a number of tasks with their prosthesis and with their normal arm for comparison. Tasks for this aspect included picking up objects, simulated feeding, stacking checkers, strength of grasp, endurance, picking up and rotating objects, and gross dexterity. On average, the myoelectric users scored higher in the tests of functional range of motion (4.3 vs. 3.6).¹³

Amputees with conventional prostheses had the most difficulty opening the terminal device behind their back and, to a lesser extent, behind their neck because of slack on the cable. Transhumeral amputees scored lower on the functional range of motion because they could not bring their prostheses into all the functional positions desired; however, range of motion was found to be significantly better in cases where the myoelectric prosthesis was used. Interestingly, in the assessment of ADLs, it was found that while tasks were performed faster with the use of a body-powered prosthesis, the subjects had to use extreme body movements such as rotating their trunk to carry out rotating a heavy object. On the other hand, those subjects with the myoelectric prosthesis were able to carry out the tasks in a more normal position. It was therefore concluded that conventional body-powered prosthetic users could only carry out the tests in a more limited range of positions.¹³

In another study completed in 1995 by Millstein, Heger, and Hunter, prosthetic use in adults was analyzed by making comparisons between body-powered and electrically powered prostheses. A total of 314 adult upper-limb amputees with either wrist disarticulation, below elbow, above elbow, shoulder disarticulations, and forequarter amputations were given a questionnaire with questions referring to the use of various types of prostheses in ADLs, work, and recreation. Patients used variations of prosthetic design including cable-operated hook, cable-operated hand, electrically powered prosthesis, and cosmetic prostheses. Many subjects had more than one prosthesis to incorporate all of their functional needs. Patients with transradial prostheses showed that, of the patients initially fit with cable operated hooks, only 69 percent were still using them, compared to those who were initially given electrically powered prostheses, where 82 percent were still wearing them. Among transhumeral amputees, acceptance rate for the body-powered prosthesis was 73 percent; for the electrically powered prosthesis, it was 86 percent. In patients with shoulder disarticulations, acceptance rate for the body-powered prosthesis was 38 percent, which was thought to be due to the high energy expenditure necessary to achieve limited function; acceptance rate was 100 percent for the electrically powered prosthesis. One of the key findings of this study was that the prostheses were well used and essential to the amputees' personal and employment activities. In addition, it was stated that most of the amputees indicated that they needed more than one prosthesis in order to achieve all of their functional needs.¹⁴

Conclusion

There is still much that needs to be done in terms of quantitatively determining the best protocol for treatment of individuals with upper-limb motion loss, particularly those with upper-limb amputation. At this point, it can be stated that interface design has a profound effect on functional range of motion for the upper-limb amputee, and progressive interface designs should be evaluated as an alternative to what has been used traditionally. More progressive interface designs have been shown to provide additional range of motion, which when combined with new technology, is helping to close the gap on functional limitations. Secondly, evidence suggests that there is functional improvement both in range of motion during ADLs as well as during bimanual activities with the use of a myoelectric prosthesis compared to that of the conventional body-powered prosthesis. Upper-limb amputees are able to appreciate greater range of motion within the functional envelope without the use of a harness. Additionally, it has been shown that upper-limb amputees can benefit from using more than one prosthesis to achieve all of their functional needs. Finally, because improvement in components continues to take place as technology advances, it is necessary to reevaluate past studies as well as existing treatment modalities for upper-limb amputees using present-day componentry in order to effectively quantify rehabilitation progress and to provide the necessary justification for providing the most functionally effective upper-limb prosthetic treatments.

Call for Further Research

The findings in this review indicate a need for a better understanding in terms of normal upper-limb movement as well as pathological movement. In order to close the gap in terms of quantifying treatment progress clinically, there must be additional research performed. It is necessary to develop a repetitive, standardized way of performing three-dimensional, kinematic analysis of upper-limb motion. Once a gold standard exists to evaluate normal upper-limb motion performing specific goal-oriented tasks, these methods can be applied in clinical settings to effectively and easily evaluate inefficiencies in movement, particularly in the functionally impaired upper-limb population.

Acknowledgments

The author wishes to thank Chris Lake, CPO, FAAOP, for his influence and his willingness to share his upper-limb knowledge and experience during weekly advisory sessions; Rob Dodson, CPO, for providing his upper-limb knowledge and recommending alternative ways to approach subject matter; Susan Kapp, MEd, CPO, LPO, for providing a solid knowledge base through my education at the University of Texas Southwestern Medical Center; and Robert Daniels, MS, CP, for his advice and knowledge of prosthetics.

References

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13. Stein RB, Walley M. Functional comparison of upper extremity amputees using myoelectric and conventional prostheses. Archives Of Physical Medicine and Rehabilitation. 1983;64(6):243–248.

14. Millstein SG, Heger H, Hunter GA. Prosthetic use in adult upper limb amputees: a comparison of the body powered and electrically powered prostheses. Prosthetics and Orthotics International. 1986;10(1):27–34.

Jayne Drummey is completing her orthotics residency in June 2009 at Hanger Prosthetics & Orthotics at Connecticut Children's Medical Center, Hartford. In July, she will begin her prosthetics residency at Hanger Prosthetics & Orthotics in Wethersfield, Connecticut. She holds a bachelor's degree in prosthetics and orthotics from the University of Texas Southwestern Medical Center Prosthetics-Orthotics Program, School of Allied Health Sciences (now called the University of Texas Southwestern School of Health Professions) and a bachelor's degree in mathematics from Dickinson College. E-mail:

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