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Overuse Syndrome and the Unilateral Upper Limb Amputee: Consequences and Prevention

Gambrell, Christina Rock BA

JPO Journal of Prosthetics and Orthotics: July 2008 - Volume 20 - Issue 3 - p 126-132
doi: 10.1097/JPO.0b013e31817ecb16
Articles
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The upper limb amputee is at risk for overuse syndrome at some point in his or her life. Although this is recognized by most prosthetists, there is currently no empirical research available to support the prevalence of overuse injuries in upper limb amputees, nor is there any research that addresses how to recognize and treat overuse symptoms before they become serious injuries in this patient population. By performing a literature review of empirical research pertaining to patients who are prone to acquiring overuse injuries, such as athletes and musicians, this article will provide descriptions of repetitive stress on the major joints of the upper extremities, and discuss how this information can be used to recognize and minimize overuse injuries in upper limb amputees.

The upper limb amputee likely will experience overuse syndrome at some point in his or her life. Although this is recognized by most prosthetists, there is currently no empirical research available to support the prevalence of overuse injuries in upper limb amputees, nor is there any research that addresses how to recognize and treat overuse symptoms before they become serious injuries in this patient population. By performing a literature review of empirical research pertaining to patients who are prone to acquiring overuse injuries, such as athletes and musicians, this paper will provide descriptions of repetitive stress on the major joints of the upper extremities, as well as discuss how this information can be used to recognize and minimize overuse injuries in upper limb amputees.

CHRISTINA ROCK GAMBRELL, BA, is affiliated with University of Texas at Austin; and Prosthetics-Orthotics Program, University of Texas Southwestern Medical Center at Dallas, Southwestern Allied Health Sciences School, Texas.

Disclosure: The authors declare no conflict of interest.

Correspondence to: Christina Rock Gambrell, BA, Prosthetics- Orthotics Program, University of Texas Southwestern Medical Center at Dallas, Southwestern Allied Health Sciences School. e-mail: Christina.Rock@utsouthwestern.edu

Overuse syndrome is a common affliction in populations such as athletes, musicians, and industrial workers.1–7 Also known as “cumulative trauma disorders,” “repetitive stress/strain injuries,” or “nontraumatic soft tissue musculoskeletal disorders,” this condition can also be a problem for amputees, especially unilateral upper limb amputees.8,9 This article will describe how applying available knowledge about overuse injuries, gained from empirical research on other patient populations, can be used to aide in the recognition and prevention of such injuries in the upper limb amputee population. First, a definition of what an overuse injury is will be provided. Second, the most common overuse injuries that affect the major joints of the upper extremity (shoulder, elbow, wrist/forearm, and hand) will be identified from literature pertaining to athletes, musicians, and industrial workers. The pathology, symptoms, and conservative treatment applications for each condition will be discussed. Last, the importance of prevention will be discussed and suggestions for preventative protocols will be provided.

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AVAILABLE RESEARCH ON OVERUSE SYNDROME IN UNILATERAL UPPER LIMB AMPUTEES

Research on overuse syndrome in the unilateral upper limb amputee population is minimal. A thorough search of the literature identifies only articles containing case studies in which therapists note the presence of overuse injuries in their patients and what their experience has been with them. One such article entitled “Save That Arm: A Study of Problems in the Remaining Arm of Unilateral Upper Limb Amputees,” authored by L.E. Jones and J.H. Davidson,9 discusses the prevalence of overuse injuries in the sound limbs of unilateral upper limb amputees seen at the Prince Henry Hospital in Australia between 1994 and 1997. In their article, they state that 50% of respondents to their questionnaire reported suffering from some form of overuse injury in their remaining sound limb. An important conclusion made from their research is that “neither lack of employment nor presence of prosthetic use is protective of the remaining arm.” This highlights the fact that no unilateral upper limb amputee is immune to developing overuse injuries, despite using a prosthesis and changing their vocational duties or status.

Another important conclusion the authors made was that counseling patients about the risk of overuse injuries is imperative. Many prosthetists and therapists consider it their goal and duty to help the amputee get back to the lifestyle they had before their amputation and to doing the activities they were doing before their injury. In the case of unilateral upper limb amputees, Jones and Davidson explain that many patients try to go about their lives as if they had had no amputation and, as a result, place themselves at great risk for developing overuse injuries. Jones and Davidson believe that, in actuality, this group of patients cannot and should not perform at the level they once could and that counseling patients about the risks of overuse injuries and how to recognize symptoms at their onset should be done.

This article by Jones and Davidson is the foundation upon which this literature review was built. Research from other fields4,10–12 supports the premise that prevention is the best approach to managing overuse injuries and that recognizing and treating symptoms at their onset can delay or even limit the development of serious overuse injuries.11–16

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DEFINING OVERUSE SYNDROME

According to the Team Physician's Handbook,17 an overuse injury can be defined as “microtraumatic damage to a bone, muscle, or tendon that has been subjected to repetitive stress without sufficient time to heal or undergo the natural reparative process.” This definition has been supported by other research.7,18–22 Overuse injuries can also be classified into four stages depending on the severity of the condition: 1) pain in the affected area after physical activity, 2) pain during activity, without restricting performance, 3) pain during the activity that restricts performance, and 4) chronic, unremitting pain even at rest.17,23 A diagnosis of overuse syndrome is usually indicated if there is persistent/recurrent musculoskeletal pain without immediate traumatic cause within the previous 6 weeks.7 Individuals with underlying medical conditions such as diabetes, rheumatoid arthritis, hypothyroidism, atypical mycobacterium, fungal infections, calcium pyrophosphate deposition, gout, Dupuytren's contracture, collagen vascular disease, and tuberculosis, are more at risk for developing overuse syndromes because of the nature of these conditions.7,24 Conditions such as diabetes and rheumatoid arthritis are common in the amputee population, therefore amputees who also suffer from diabetes or rheumatoid arthritis may be more at risk to develop overuse injuries than amputees who do not suffer from such conditions.

The body responds to repetitive use by adaptation of tissues. Bone, muscle, and tendinous/ligamentous tissues all adapt in their own ways. Bone tissue adapts to external stress according to Wolf's law by increasing its load-bearing capabilities. Muscle tissue increases in size and strength by hypertrophy of existing fibers, and tendinous/ligamentous tissue adapts by increasing collagen content, collagen cross-linking, and mucopolysaccharide content.7,13 A study conducted by Nakama et al.21 on the effect of repetition rate on the formation of microtears in tendon in an in vivo cyclical loading model, investigated the microstructural changes that occur in the flexor digitorum profundus tendon of a rabbit, due to different repetition rates. Their study revealed that a higher repetition rate (60 reps/min with 0.8 second rest) when compared with a lower repetition rate (10 reps/min with 4.8 second rest) caused relatively small tears in multiple parts of the tendon and the lower repetition rate caused larger tears in fewer parts of the tendon. They concluded that repetition rate is associated with increased tendon microtears in a dose-response pattern. This study illustrates the mechanism and definition of overuse injuries as stated earlier, and gives further insight as to how overuse injuries can be treated and prevented.

The body's nervous system also exhibits a response to the amputation of a limb. In a study conducted by McComas et al.25 on the long-term effects of partial limb amputation in man, the researchers studied the neurological changes that accompany amputation. Their study involved electrically stimulating the ulnar nerve in both the residual limb and sound limb of unilateral upper limb amputees, and comparing the resulting mean impulse conduction velocities to those of the control subjects who did not have any amputations. Their results revealed that reflex excitation and inhibition of the triceps motorneurons in the amputated limbs were similar to those found in the limbs of control subjects; however, reflex inhibition in the sound limbs of the amputees was reduced, possibly as a consequence of overuse.25 The results of this study suggest that there may be a neurological risk factor predisposing unilateral upper limb amputees to overuse injuries in the sound limb.

According to Verdon,7 overuse syndromes are comprised of three clinical stages. The first stage is characterized by fatigue, increased aching and tiredness during the activity/work shift that subsides with overnight rest. She states that this stage should be considered a warning, as the body tries to protect the affected tissues. The second stage is characterized by a persistence of the discomfort into the next day, with an earlier onset of fatigue, and repeated injury and release of inflammatory agents. This stage signifies that an injury is developing and that action should be taken to reduce the strain on the affected tissues, modify the aggravating activities, and schedule frequent resting periods. The third stage is characterized by chronic fatigue, aching, and weakness that persists despite rest. This stage is a warning that fibrosis may be developing in the affected tissues.

In her article on overuse, Verdon also identifies occupational risk factors for the development of overuse syndromes. Many of these risk factors pertain to the daily routines found in the amputee population. These risk factors include repetition, high force, awkward joint posture, direct pressure, vibration, and prolonged constrained posture.7,14 The unilateral upper limb amputee patient may have a problem avoiding many of these risk factors because of the natural heavy reliance on the sound limb, so it is important that prosthetists and other clinical team members educate their patients on the risks of overuse injuries so that the patient can implement preventative measures in their daily routine.

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COMMON OVERUSE INJURIES OF THE UPPER EXTREMITY

By reviewing evidence-based literature on populations who are prone to acquiring overuse injuries, such as athletes, musicians, and industrial workers, injuries commonly affecting the major joints of the upper extremity were identified. These injuries were then compared with the common overuse injuries listed in the article by Jones and Davidson,9 and the following overuse injuries were selected to be examined in this article. At the shoulder, the most common injuries associated with overuse were rotator cuff injuries including tendonitis and tears, shoulder impingement, and bursitis.4,9,15,26 At the elbow, common overuse injuries were found to be lateral and medial epicondylitis.1,3,4,9,10,14,18,20,27–29 At the wrist/forearm level, common overuse injuries were found to be carpal tunnel syndrome, tendonitis of the forearm flexors, and tendonitis of the forearm extensors.4,9,15,30,31 Last, in the hand and fingers, common injuries were found to be De Quervain's Syndrome and Trigger Finger.7,9,10,14,22,24,27,31,32

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OVERUSE AT THE SHOULDER

One common overuse injury of the shoulder is Rotator cuff tendonitis. This condition, which can also be called “supraspinatus tendonitis,” is prevalent in industrial work-related upper extremity musculoskeletal disorders. The rotator cuff is comprised of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. Tendonitis occurs when there is impingement of these cuff structures on overlying bone.26,27 Patients will typically present with weakness, tenderness, and pain in the superior or lateral shoulder that may radiate down the arm. There also may be limited motion in shoulder abduction and external rotation.27 Causal verification of impingement can be achieved by reproduction of pain with forward shoulder flexion to 90° with internal rotation of the humerus; this is also called the Hawkins impingement sign.27 Other diagnoses that can cause similar shoulder pain include subdeltoid bursitis, biceps tendonitis, arthritis, and pain from cervical radiculopathy.27

Conservative treatment of rotator cuff tendonitis includes resting the shoulder, avoiding all overhead work/activities for 1–3 weeks, limitation of raising arms, nonsteroidal antiinflammatory drugs (NSAIDs), and steroidal injections if necessary to reduce acute pain. The shoulder should not be immobilized because this will increase the risk of developing adhesive capsulitis.27 After the acute pain has subsided, physical therapy consisting of gentle range of motion (ROM) and strengthening exercises should be implemented.27 Like many other tendonitis conditions, surgery is an option if all conservative measures fail to resolve the symptoms.

Another common overuse injury occurring at the shoulder is Subdeltoid Bursitis, also called “subacromial bursitis.” This inflammatory condition affects the subdeltoid bursa, which lies beneath the deltoid muscle, above the rotator cuff and extends beneath the acromion.27 Patients with this condition will typically present with dull, aching pain, edema, tenderness, and restricted shoulder movement; however, muscle strength will not be affected.27 Diagnosis of subacromial bursitis may be difficult because the symptoms are very similar to those of rotator cuff tendonitis, and referred pain from cervical disorders, bicepital tendonitis, and arthritis.

Treatment for bursitis is initially conservative, including resting of the shoulder, NSAIDs, ice and heat applications, followed by gentle reconditioning through physical therapy once acute symptoms have subsided.27

The majority of shoulder injuries typically result in a temporary reduction in the shoulder's ROM due to pain or edema. Because the shoulder is the most proximal joint in the upper extremity, limitations in its ROM will also limit the positioning of the elbow and hand in space. This reduces the patient's functional working area, preventing them from doing activities away from the body or over their head. This can be a debilitating side effect for a unilateral upper limb amputee who already has a compromised shoulder due to injury, or is not proficient in using their prosthesis, and thus relies heavily on their sound limb.

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OVERUSE AT THE ELBOW

One of the most common overuse injuries affecting the elbow is lateral epicondylitis. Also known as “tennis elbow” or “lateral tendinosis,” this condition is generally believed to arise from overuse of the extensor tendons of the forearm which causes chronic microtears of extensor tendons and subsequent collagen degeneration and development of granulation tissue.10,14,20,28 Symptoms associated with this condition include: pain located distal to or directly over the lateral epicondyle, with or without pain radiating distally into the forearm and with or without accompanying weakness during grasping.14,20,27–29 Some common physical findings include: the reproduction of pain with resisted wrist extension, especially when the forearm is in pronation, pain with resisted supination, and tenderness with palpation over the lateral humeral epicondyle.10,14,20,27–29 The patient will typically present with a history of occupation or activity-related pain at the lateral elbow, and care should be taken to differentiate a diagnosis of lateral epicondylitis from other conditions that can cause similar pain, including arthritis of the elbow, collateral ligament injuries, cervical radiculopathy, radial tunnel syndrome, carpal tunnel syndrome, and rotator cuff tendinosis.10,29

Treatment for mild to moderate cases is typically conservative initially and may include combinations of the following: actively avoiding aggravating activities, resting the arm, counterbracing with a compressive tennis elbow strap, use of NSAIDS, and/or application of ice.10,14,27,29 More severe cases of lateral epicondylitis may require the use of corticosteroid injections and surgery when all conservative measures fail. Whether the patient's symptoms are mild or severe, once acute pain and inflammation has been resolved, a rehabilitative program consisting of stretching, strengthening, and modifying work tasks or body mechanics is typically implemented.10,14,27,29 In his article, “Overuse Injuries of the Upper Extremity in Golf”10 the author, McCarroll, divides the treatment program for lateral epicondylitis into four stages: 1) the relief of acute or chronic inflammation through the use of rest, ice, NSAIDs, and splinting, 2) physical therapy treatment that stresses flexibility of the muscles and eccentric exercises to strengthen muscles in conjunction with cross-friction massage, 3) decreased movement of force at the wrist (through alteration of swing mechanics), and 4) corticosteroid injections if all other conservative treatments failed, followed by surgery as a last resort. If left untreated, symptoms may persist for an average of 6–24 months, which can be debilitating for a unilateral amputee. The literature states that lateral epicondylitis occurs equally among men and women and typically becomes an issue between the ages of 35 and 50.28,29 This indicates that unilateral upper limb amputees in this age group may be more at risk than younger amputees to experience lateral epicondylitis.

Medial epicondylitis, also known as “Golfer's Elbow,” although less common than lateral epicondylitis, is the most common cause of medial elbow pain.20,29 Similar to its lateral counterpart, medial epicondylitis involves chronic microtears in the common flexor pronator origin, specifically the origins of the pronator teres and flexor carpi radialis muscles, because of repetitive wrist flexion and resisted pronation.14,20,27,29 Patients typically present with medial elbow pain of insidious onset, which radiates into the medial forearm. Patients will also present with tenderness over the medial epicondyle and may also experience weak grip strength.14,20,27,29 Medial elbow pain can also be caused by ulnar neuropathy, arthritis, and medial collateral ligament damage so care must be taken to correctly eliminate these other possible conditions.27,29 In a literature review done by Kandemir et al.29 the authors state that over half of patients diagnosed with medial epicondylitis also suffer from ulnar neuropathy concomitantly.

Treatment for medial epicondylitis is similar to that of lateral epicondylitis with a few exceptions. Instead of using a tennis elbow strap for counterbracing, many health care providers prefer the use of a soft elbow pad that wraps around the elbow to protect the medial elbow from trauma caused by leaning on a hard surface such as a table. Also, even though a corticosteroid injection can aid in pain relief, it is contraindicated for treatment of medial epicondylitis because there is a strong possibility of damaging the ulnar nerve.14,27,29 Surgery is not typically advised for the same reason making this type of overuse injury hard to resolve.14

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OVERUSE AT THE WRIST

The most common peripheral nerve entrapment problem is manifested as carpal tunnel syndrome.1,11,30 Carpal tunnel syndrome (CTS), develops from entrapment of the median nerve in the carpal tunnel of the wrist. Increased pressure in the carpal tunnel increases pressure on its contents, including the median nerve, which can cause the nerve to generate random action potentials, local demyelination, axonal loss, and even stimulate increased amounts of subsynovial connective tissue that can crowd the tunnel and further increase pressure.1,11,27,30 Wrist flexion and extension, and finger flexion raise the pressure in the tunnel and can aggravate CTS symptoms.1 Symptoms of CTS include: parasthesias or pain in the thumb, first and second fingers, and half of the third finger; weakness or clumsiness of the hand; dull, aching discomfort in the hand, forearm or upper arm; dry skin, swelling or color changes in the hand; provocation of symptoms by sleep, sustained hand or arm positions, or repetitive actions of the hand or wrist; mitigation of symptoms by changing hand position or shaking the wrist. Some patients may have pain or sensations that radiate throughout the hand and/or throughout the arm up to their shoulder. Although the role overuse plays in the causation of CTS is still controversial, it is reported that most patients present with symptoms in their dominant hand first.1 For a unilateral upper limb amputee, the sound limb typically becomes the dominant arm and hand, whether or not it was before amputation. Since research on CTS in unilateral upper limb amputees has yet to be studied, it should not be assumed that CTS cannot be a result of overuse, especially in an amputee.

The diagnosis of CTS can generally be made without the use of a nerve conduction study, even though it is considered the gold standard.1,30 Generally, a preliminary diagnosis can be made based on the number of symptoms the patient has and whether they score positively on provocative tests such as Phalen's sign and Tinel's sign.1,30 There are several conditions that can be confused with CTS and should be ruled out before a definitive diagnosis of CTS. They include: cervical radiculopathy, ulnar neuropathy, Raynaud's phenomenon, Vibration white finger, Osteoarthritis of the metacarpophalangeal joint of the thumb, tendonitis, multiple sclerosis, syringomyelia, motor neuron disease generalized peripheral neuropathies, and diabetes mellitus. Many of these conditions can predispose an individual to CTS or can coexist with CTS, so it is important to review specific symptoms of these conditions so they can be ruled out as a diagnosis.1,30 The American Academy of Neurology recommends that treatment of CTS begin conservatively with the use of splints, activity modification, and NSAID and diuretic use to reduce swelling. If conservative measures do not improve symptoms, steroid injections should be used. Both systemic and local steroids have been shown to be effective, however local steroids may be found superior to systemic steroids because they are associated with no systemic side effects.1,30 If steroidal treatment fails, then carpal tunnel decompression surgery can be used as a last resort.

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OVERUSE AT THE HAND/FINGERS

Stenosing tenosynovitis of the first dorsal compartment, most commonly known as De Quervain's Syndrome, is a common condition that affects many populations of individuals including athletes, musicians, industrial workers, and even new mothers.7,14,22,24,27,32 Also nicknamed “Baby Wrist” and “New Mothers' Disease,” De Quervain's syndrome is caused by repetitive gliding of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons over the radial styloid, located beneath the sheath of the extensor retinaculum. Cumulative microtrauma to the tendons leads to inflammation of the surrounding synovium and myxoid degeneration within the tendon sheath wall.7,22,31,32 Development of this condition is associated with repetitive, forceful grasping with the wrist in ulnar deviation, or, prolonged positioning of the wrist in flexion and ulnar deviation coupled with thumb extension, as if holding a baby.7,22,24,32 Common symptoms that accompany this condition include edema, tenderness, and pain localized over the radial aspect of the wrist and thumb. Depending on the severity of the condition, pain may radiate proximally into the forearm or medially into the first finger and dorsum of the hand.7 One predisposing factor associated with the development of De Quervain's syndrome is an anatomic variation in the APL and EPB tendons. Approximately 30% of the population has a septum that divides the APL and EPB tendons and the majority of patients with De Quervain's have this deviation.7 The development of De Quervain's is also associated with the development of other overuse injuries such as Trigger Finger and Carpal Tunnel Syndrome.7 Diagnosis of De Quervain's includes presentation of typical symptoms and a positive Finkelstein's test.7,22,32

Conservative treatment of mild stages of De Quervain's syndrome includes rest and immobilization supplemented with NSAID use to reduce swelling.7,22,24,27,32 Some studies suggest the full-time use of a thumb spica; however, the benefits of splinting are still controversial.7 Steroid injections have also been reported to provide pain relief along with physical therapy, strengthening, and modification of activities.7,22,24,32 If after 6–8 weeks of conservative treatment there is a total lack of progress, surgical release may be indicated.7

Another common overuse injury affecting the hand and fingers is Trigger Finger. Trigger Finger, also considered a form of stenosing tenosynovitis, is caused by the thickening of the proximal portion of the flexor tendon sheath.7,24,27 Aggravating movements that lead to this inflammatory response are repetitive, forceful gripping, and direct pressure over tendons.7,24,27 Symptoms that accompany this condition include pain, triggering, and even locking of the finger or thumb in a flexed position at the level of the metacarpal head. The locked position results because the finger extensors are weaker than the finger flexors.7

Conservative treatment of this condition includes rest, splinting, exercises, warm water soaks and massage, activity modification and NSAID use. In her article “Overuse Syndromes of the Hand and Wrist,” Verdon7 states that steroid injection directed into the fibro-osseous tunnel of the affected finger should be the initial treatment for Trigger Finger, and that surgery should be undertaken if there is no response to steroid injection and symptoms have been present for 3 months or more since the initial visit.

Both of these injuries temporarily reduce the ROM available in the thumb or fingers, and in the case of De Quervain's syndrome, thumb opposition is compromised as well. Even if a unilateral upper limb amputee is proficient in using their prosthesis, no terminal device currently available has the ability to replace the full dexterity of the natural fingers. Thus an injury to the sound side hand can be debilitating.

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PREVENTION

Several researchers have concluded that the most effective treatment for overuse injuries is prevention.4,10–12 Making the patient aware of the risks and repercussions of overuse injuries, and counseling them on the early detection and immediate intervention of conservative treatment at the onset of symptoms, it is thought that serious injuries can be prevented or at least delayed.11–16 But evaluating the effectiveness of preventative measures is difficult. The only way to know how well a preventative measure works is to measure how long it takes for it to fail. So, what is the best way to approach this conundrum? It is this author's opinion that the best thing a treating professional can do for their patient is to provide mandatory education on overuse syndrome that includes the short and long-term effects of overuse injuries, early detection of symptoms, conservative treatment protocols, and counseling on lifestyle changes and the potential psychosocial effects that can accompany the condition. Typically, the new amputee is focused on the missing limb and on lost capabilities, and not focused on preservation of what they have remaining. It is crucial that the patient recognize and respect the severity and potential life-altering effects that overuse injuries can have. This responsibility may appear to belong primarily to the patient's occupational and physical therapists; however, not all therapists appreciate the extent of problems facing the unilateral upper limb amputee, and therefore focus only on helping the patient learn to use their prosthesis, and to simply avoid using the sound limb to do everything. Even if it is known that the treating therapist educates the patient about overuse syndrome and teaches them preventative measures and lifestyle changes, it is the treating prosthetist's responsibility to provide this education to the patient as well. Furthermore, the treating physician maybe the first and only resource for the individual with upper limb loss as not all amputees see a prosthetist or therapist.

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OF SPECIAL INTEREST

Stroke patients with hemiparesis are in a similar situation as unilateral upper limb amputees because both groups of patients lack the ability to use one of their arms. In an article entitled, “Carpal Tunnel Syndrome Involving Unaffected Limbs of Stroke Patients'” the author, Sato et al.33 examined the nonparetic upper limb in stroke patients for evidence of subclinical CTS. They state that hemiparesis is the most common neurological abnormality after stroke and that the nature of this disability leads to regular, repetitive overuse of the contralateral wrist and hand. Because the development of CTS is commonly caused by repetitive use of the hand and wrist, the authors believe that repetitive overuse of the nonparetic hand and wrist in a stroke patient may cause him or her to develop CTS.

To evaluate their hypothesis, the authors identified 132 stroke patients with hemiparesis, and 56 control subjects who did not suffer a stroke and did not have hemiparesis. Both groups of subjects were chosen using thorough exclusion criteria, and were matched by age and sex. The stroke patients were further divided into two groups: 61 patients with a “functioning hemiparetic hand” and 71 patients with a “disused hemiparetic hand.” Several neurological exams were performed on the unaffected hand and wrist and were evaluated for signs and symptoms of CTS which included: numbness, tingling, pain in the hand; paresthesias in the median nerve distribution pattern; dry skin or color change over the palm; thenar muscle atrophy; and Tinel's sign (lightly tapping the nerve to elicit a “pins and needles” feeling in the distribution of the nerve) and Phalen's sign (placing the wrist in flexion for 1 minute to reproduce symptoms). A comparison was also made between stroke patients who used an assistive device to those who did not. Because numerical values were able to be obtained, thorough statistical analyses were able to be used to evaluate the results.

Some of the key findings from their study include: 1) Tinel's sign was found in 57.7% of the disused hand group and only 31.1% of the functioning hand group, 2) all electrophysiological indices performed were significantly prolonged or reduced for the median nerve on the unaffected side vs. the paretic side, 3) a higher percentage of patients with a disused hand deviated >2 SD from control means for the indices than when patients had a functioning hand, and 4) no significant differences were found in the occurrence of signs and symptoms of CTS between the assistive device-using group versus the nondevice using group. The authors state that, “the determinant of CTS on the unaffected side is not use of an assist device but functional severity of palsy of the opposite hand.” Several conclusions can be deduced from these findings as they relate to unilateral upper limb amputees. First, that the presence of a functioning prosthesis may limit the development of overuse injuries when compared with the use of a static, cosmetic prosthesis or no prosthesis at all. Second, the more impaired the affected limb is, the more likely the unaffected side will suffer from overuse.

The implications of this study are great, and perhaps a more thorough review of the literature pertaining to this patient population will provide more evidence for the connection between overuse syndrome and the unilateral upper limb amputee.

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FUTURE RESEARCH

Currently, injuries affecting the contralateral limb of unilateral upper limb amputees are treated as separate entities, independent of the condition of the amputated arm. Most insurance companies do not recognize the association between amputation of a limb with the development of overuse injuries in the remaining limb(s). We know that amputees, with either upper or lower limb loss, will most likely develop some form of overuse injury in their contralateral limbs because the human body adapts to change. Compensation will occur as a matter of survival. There is a knowledge void which beckons the need for empirical research in the prosthetic field to validate this clinical observation. While such evidence-based research on overuse matures, patient education on the risks of overuse is paramount to break the seemingly overlooked and insidious cycle.

Research utilizing 3D motion analysis techniques with the upper limbs has begun, but it is not widespread and data obtained from this research has not been made available to date. Once the use of this technology becomes more widespread in the field of upper limb prosthetics, we may be able to identify “deviations” in normal upper limb movement and have the ability to normalize these deviations with the use of different prosthetic components.

Another area in need of research is the prevalence and types of overuse injuries being seen, and, what the incidence of overuse is at differing amputation levels and what effects varying forms of prosthetic management may have on this incidence. Once a more accurate database system is established, we will be able to identify what overuse injuries patients with amputations are developing, what the common overuse injuries are at each amputation level, and to what degree the upper limb amputee population is suffering from overuse. The more we can learn about our patients, the more we can help them.

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ACKNOWLEDGMENTS

The author thanks the following individuals: Chris Lake, CPO, LPO, FAAOP, for providing the opportunity to research this subject, for his continuous help and guidance throughout my research, and for his support in helping me submit this manuscript for publishing; Rob Dodson, CPO, for his help and guidance throughout my research; Susan Kapp, CPO, LPO, and Robert Daniels, CP, LP, for acting as my advisors on this project; Judy Davidson, OTR/L, for communicating with me during my research; and Roger Gambrell II, for his continuous love and support.

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Keywords:

overuse syndrome; repetitive stress; amputee; amputation; prevention; upper limb

© 2008 American Academy of Orthotists & Prosthetists