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DUALEVE Chief Executive Officer: Peter Wallerson Chief Marketing Officer: Han You Chief Technical Officer: Sun Murray Han Chief Regulatory Officer: Zwoisaint Mears-Clarke Chief Financial Officer: Angel Castro 1 Table of Contents I. II. III. IV. V. VI. VII. Design Problem and Design Brief Research Design Fundamental Requirements and Constraints Preliminary Designs Decision Matrix Proof of Concept Plan Proof of Concept Outcome Page 1 Page 3 Page 40 Page 43 Page 48 Page 50 Page 53 1 I Design Problem and Design Brief 2 i. Design Problem Long term wheel chair users have a high incidence of upper body pain, fatigue, and injury due to increased upper limb usage. Current solutions have been found to be inadequate in solving the problem: wrist braces are restrictive and can cause muscle atrophy in wrist flexors and extensors, electric wheelchairs can cost upwards of $1000 and usually require a prescription (and also cause muscular atrophy), surgery is both invasive and carries a high risk of nerve damage. Additionally, other forms of alternative propulsion wheelchairs simply transfer the unhealthy loading form one body part to another, and attract a lot of unwanted attention to their users. ii. Design Brief We propose to develop a new device that reduces the incidence of upper body injury in long term manual wheel chair users. The device will be (most importantly) discrete, nonrestrictive, affordable for average consumers, and non-invasive. iii. Solution Neutral Needs Statement A way to reduce the incidence of upper body injury in long term manual wheel chair users. 3 II Research 4 A. Basic Summary of the Problem – Upper body injuries due to Manual Wheelchair use A1. W HEEL C HAIR USE i) T YPES OF WHEELCHAIRS There are a number of ways to classify wheelchairs, but generally, they can be separated into two inclusive categories. There is a category of wheelchairs which are designed for daily mobility and a category of wheelchairs which are designed with a specific sport in mind. This separation can be made since the types of biomechanical stressors each category experiences are likely to be different. While there is overlap between the injuries suffered between users of chairs in both categories, the focus will be placed on wheelchairs used for daily mobility. For everyday use, persons with mobility limitations may use: manual wheelchairs push-rim activated power-assisted wheelchairs (PAPAWs) battery-powered wheelchairs scooters ii) D EMOGRAPHICS In December of 2008, the United States Census Bureau released the Americans with Disabilities: 2005 report. In this report, the population with lower body limitations was of our concern. Of people aged 15 and older: ~ 27.4 million (11.9%) had difficulty with ambulatory activities of the lower body ~ 22.6 million people (9.8%) had difficulty walking a quarter of a mile and ~12.7 million were not able to perform this activity ~3.3 million people (1.4%) used a wheelchair or similar device ~10.2 million (4.4%) used a cane, crutches, or walker to assist with mobility. This report, using data collected from June through 2005, provided estimates representative of the civilian non-institutionalized population living in the US, meaning that the disability statuses of people living in places such as nursing homes were not included. Inclusion of this population would, on average, increase the estimate of disability prevalence by about 0.6%. The American Community Survey provides detailed and up-to-date estimates that can shed light on the current population and disability prevalence as soon as 2009. According to ACS, in 2009, an estimated 19,425,100 out of 281,613,500 (6.9%) of the non-institutionalized population in the United States reported an ambulatory disability. 5 Table 1. Wheelchair use, by age and gender Any wheelchair Manual wheelchair Electric wheelchair Number (1000s) % of population Number (1000s) % of population Number (1000s) % of population 1,599 0.61 1,503 0.58 155 0.06 Under 18 88 0.12 79 0.11 18 0.02 18-64 614 0.39 560 0.35 90 0.06 65+ 897 2.87 864 2.76 47 0.15 Male 658 0.52 606 0.48 84 0.07 Female 941 0.70 897 0.67 71 0.05 Total Age Gender iii) B IOMECHANICS Biomechanical studies have been done in order to produce an analysis of wheelchair propulsion. Chow et al, summarize a number of these studies into three areas: kinematics, kinetics, and muscle timing and activation. Kinematics provides a description of the bilateral cycle motion that occurs in the turning of the wheels of a wheelchair. This cycle starts at the instant the hand contacts the push-rim, and ends at the instant immediately before the next hand contact on the same wheel. The instant the hand loses contact with the rim (hand release) divides a stroke cycle into two phases – push and recovery phases. Kinetics provides an analysis of the resulting upper limb joint loads. The locations, magnitudes, and directions of the force and moment acting on the hand during the push phase are used to determine the resultant joint forces and moments using the inverse dynamic approach. Contact forces and moments between the hand and push-rim are usually measured using either a wheelchair ergometer/dynamometer or an instrumented wheel. It has been shown that low intensity wheelchair propulsion does not appear to lead to high glenohumeral contact forces. However, shoulder resultant joint forces and moments increase considerably when pushing at faster speeds up an incline or while fatigued. 6 Several studies have documented the muscle activation patterns during wheelchair propulsion using surface and indwelling electromyographic (EMG) techniques. In general, anterior deltoid, biceps brachii, triceps brachii, flexor carpi radialis, extensor carpi radialis, and pectoralis major have been found to be active during the push phase, while the middle and posterior deltoid muscles are identified as the prime movers during the recovery phase. Cerquiglini et al. [89] found the latissimus dorsi to be most active during the final phase of pushing, and the activity increased drastically when the resistance of the wheelchair ergometer was increased to simulate a 2–3% incline. Using indwelling EMG techniques to monitor different shoulder muscles, Mulroy et al. [47] found the anterior deltoid, sternal portion of pectoralis major, supraspinatus, infraspinatus, serratus anterior, and long head of biceps brachii to be active during the push phase. The recovery phase muscles were middle and posterior deltoid, subscapularis, supraspinatus, and middle trapezius. They did not observe any consistent pattern of activity in the latissimus dorsi. They concluded that the pectoralis major, supraspinatus, and all recovery muscles were most vulnerable for fatigue. A2. I NJURIES Wheelchair propulsion is very stressful to the musculoskeletal structures of the upper limb; however the incidence of musculoskeletal problems in wheelchair users is poorly documented. Physicians who frequently care for these patients recognize that pain in the arms is considerably more frequent than in the general population. Nichols et al. observed that 51.4% of respondents to a questionnaire, sent to members of the Spinal Injuries Association in Great Britain, suffered shoulder pain. The actual lesions causing pain were not identified. It appears that patients at greatest risk are those with weakness of arm muscles (e.g., patients with neuromuscular disorders and rheumatoid arthritis). Painful conditions of the arms are predictable; for the wheelchair bound person the arms are the limbs of mobility and weight bearing. For the very active, the arms are subjected to unusual stresses many times a day, in supporting the person's weight when transferring from chair to bed, toilet, car and other seats. Intercurrent causes of arm pain include musculotendinous rotator cuff disorders, cervical disorders with referred pain to the arm, acromioclavicular strain, tendinitis and bursitis of the elbow, strains and sprains of tendon and ligament structures of wrists and hands. The mechanical stresses sustained by the arm and hand joints would predispose them to early degenerative changes. Another complaint, not commonly recognized, is carpal tunnel syndrome. This neuropathy has a predilection for people who perform repetitive movements with their wrists. iv) S HOULDER A. E TIOLOGY /P HYSIOLOGY Shoulder overuse is believed as major factor in causing shoulder pain [1–3]. Additionally, using inappropriate manual technique in performing wheelchair propulsion may be another reason in causing shoulder pain. Although the underlying etiology of shoulder pain in this population is not understood completely, ‘impingement’ of the subacromial structures during transfer or wheelchair activities has been suggested as one of the major causes of this problem. The impingement refers to the mechanical phenomenon in which contact between the anterior aspect of the humerus and the acromial arch creates compressive force on the subacromial structures when the glenohumeral joint (GHJ) is moved. When the compressive 7 force is sufficiently large or if the impingement is repeated over a long period of time, pathological conditions such as bursitis, tendonitis or rupture of rotator cuff tendons may develop. Shoulder impingement pain usually occurs when wheelchair user places his or her arm in position of flexion abduction and internal rotation. Pain often locates between the top of the humerus (arm bone) and the acromion (tip of the shoulder). According to Cooper, Boninger et al in a paper published in 1998, “the most common disparity in strength associated with rotator cuff tear or tendinitis is an imbalance between the internal and external rotators of the shoulder.”1 Furthermore, “shoulder muscle imbalance, with comparative weakness of the humeral head depressors (rotators and adductors), may be a factor in the development and perpetuation of rotator cuff impingement syndrome in wheelchair athletes”2 and wheelchair users in general. “As a result of years of wheelchair propulsion, shoulder muscles active during the push phase are believed to become stronger, whereas the muscles that are involved during the recovery phase remain at the same strength”3. B. D EMOGRAPHICS Manual wheelchair users frequently complain about shoulder pain [1–3]. It has been estimated that between 30% and 70% of wheelchair users complained of past or current shoulder symptoms [1]. v) CTS A. A NATOMY /P HYSIOLOGY The carpal tunnel is bordered dorsally by the concave arch of the carpus and volarly by the transverse carpal ligament (TCL), with a variable depth of 10 to 13 mm.6 Ten structures from the volar forearm pass through the carpal tunnel—nine flexor tendons and the median nerve (Figure 1). The median nerve is the most superficial structure within the canal, entering the space in the midline or just radial to the midline. The median nerve may divide in the forearm or split within the carpal tunnel. Both conditions are associated with a persistent median artery. The thenar motor branch of the median nerve usually originates in an extraligamentous position distal to the TCL. Less commonly, the motor branch projects from beneath the TCL (subligamentous) or perforates through the TCL (transligamentous).7 The median nerve is susceptible to compression within the carpal canal because of the unyielding fibroosseous borders. Normal pressure within the carpal tunnel measures 2.5mmHg. A decrease in epineural blood flow and edematous changes occur when the pressure reaches 20 to 30 mm Hg. At pressures >30 mm Hg, nerve conduction diminishes. A continued rise or a prolonged elevation in pressure may lead to a complete median nerve block. 1. Ambrosio, F. B., & al, e. (2005). Biomechanics and Strength of Manual Wheelchair Users. Journal of Spinal Cord Medicine , 407-414. 2. Burnham, R. S. (1993). Shoulder pain in wheelchair athletes. The American Journal of Sports Medicine , 238-242. 3. Cooper, R. A., Boninger, M. L., & Robertson, R. N. (1998). Heavy Handed: Repetitive Strain Injury Among Manual Wheelchair Users. TEAMR EHA Report 35 , 35-38. 8 B. E TIOLOGY Acute CTS is caused by a rapid and sustained increase in pressure within the carpal tunnel. The onset of symptoms is sudden and may prompt a decision for urgent surgical decompression. Precipitating factors producing acute CTS include wrist trauma, infection, high-pressure injection, and hemorrhage.11 Chronic CTS is a much more frequent condition, with the pathogenesis divided into four categories: idiopathic, anatomic, systemic, and exertional. C. E XERTIONAL In the workplace, CTS has been attributed to repetitive use of the wrist and digits, to repeated impact on the palm, and to the operation of vibratory tools.17-19 Extremes of wrist flexion and extension have been shown experimentally to elevate pressure within the carpal tunnel.9 Finger flexion also increases the interstitial canal pressure as the lumbrical muscles are drawn proximally.20 Task-related factors are variable and inconsistent, however, and the mechanisms by which they may contribute to CTS are poorly defined.19 A direct relationship between repetitive work activity (eg, keyboarding) and CTS has never been objectively demonstrated. D. K INETICS Average peak wrist joint angles during the push phase were: ulnar deviation, -24 ± 11° radial deviation, 13 ± 12° flexion, -14 ± 18° extension, 34 ± 16°. The values for ulnar and radial deviation were close to normal values for maximal range of motion (ROM) found in the literature. Peak extension was approximately 50% of ROM. The peak angles which occurred with concurrent activity of the wrist flexors were: ulnar deviation, -22 ± 11° radial deviation, 13 ± 10° flexion, -16 ± 15° extension, 32 ± 16° (Veeger et al, 1998). The large deviation and extension angles, especially those recorded simultaneously with wrist flexor activity, are serious risk factors for CTS. This finding may help explain the high rates of CTS in the wheelchair user population. Gellman et al (4) found a serious elevation of pressure in the carpal tunnel when the wrist was in full active flexion or full active extension. They suggest that the etiology of CTS in the WU population may be a combination of the repetitive trauma from the propulsion of a handrim wheelchair and of ischemia resulting from increases in pressure in the carpal tunnel during extreme extension. Combination of the above indicates that wrist movement and muscular activity pattern during handrim wheelchair propulsion may be important factors in the development of CTS in the WU population. E. D EMOGRAPHICS In a study by Aljure et al (1985), the incidence of carpal tunnel syndrome at 1-10 years from injury onset was; 54% at 11 - 20 years from injury onset; around 54% at 21 - 30 years from injury onset; and then a significant increase to 90% at 31+ years from injury onset. This study suggests median and ulnar nerve functional testing within 5 years of injury even if the person is asymptomatic, with periodic reevaluations after that. With this in mind, the best treatment for carpal tunnel becomes prevention. 9 A3. WHO IS THE CUSTOMER? We expect our device to be purchased by insurance companies and long-term manual wheelchair users. How do insurance companies decide what can be reimbursed? 1) In most cases, a committee is charged with the responsibility for coverage policy. The committee is chaired by one of the corporate medical directors. The request for coverage can be initiated by a provider, by a patient, or by a manufacturer. 2) At a minimum, payers (e.g. medical insurance companies) require that the device have Food and Drug Administration (FDA) approval before even considering a review. 3) Payers will look for unbiased clinical literature that documents the safety and the efficacy of the product. Most payers use an external assessment company (e.g. Hayes, ECRI, or the Blue Cross Blue Shield Technology Evaluation Center) to review the literature and provide a recommendation. The payer may supplement the information with its own literature review, or it may use outside clinical consultants to review the data. 4) Physician advocacy is an extremely important component of the coverage decision making process. The more physicians who indicate an interest and belief in the product, the stronger the case will be. If the manufacturer initiates a coverage review, it is important to identify a group of supporting physicians who are willing to champion the product to a payer. The physicians should be participants in the payer’s network and ideally should be viewed as leaders within the community. 5) After reviewing all of the documentation, the committee makes a final determination. Although the time frame varies, most decisions are made within six months. 6) If the payer decides to deny coverage, there is generally an appeals process within each state. Therefore, if our product is to be reimbursed, it needs to be FDA approved, safe and effective, and strongly endorsed by clinicians. There could be a delay between starting to sell and have patients use the product, and the cost of the product being reimbursed by the patient’s insurance company. A4. WHO IS THE USER? Our product will be directed towards those who are long term manual wheelchair users. We expect that most users will be 15-60 years old. This is a broad age group, but there are common uniting factors. Users will be unwilling to use a device that is indiscrete and calls more attention that a standard wheelchair. Users will want a device that is simple to learn, and does not require much more effort to use than a standard wheelchair. A5. S UMMARY 10 What we propose is a low-cost device that provides users with at least the same mobility that a wheelchair does, while reducing and/or eliminating stress felt on the upper body. This can be achieved by engaging major muscle groups that can handle repetitive strenuous motion and avoiding placement of the wrist and shoulders in an unnatural, deteriorative state. The prospective customer of this interface would be insurance companies and the end-user. A cost-effective product will allow the end-user to purchase the device without the need of an insurance company. But those with insurance will potentially have theirs covered by insurance companies, since this would prevent future medical issues that cost insurance companies more money later on. B . E XISTING P RODUCTS Current products to treat carpal tunnel include wrist splint to restrict wrist movement, nonsteroidal anti-inflammatory drugs to relieve swelling, corticosteroid injection, surgery, and a variety of carpal tunnel prevention products. Long-term wheelchair users often experience symptoms of carpal tunnel because of repetitive strain on the wrist, and the use of electric wheelchairs is also opted for treatment. The commonly used wrist splint restricts movement and help ease symptoms; however, patients experiencing symptoms of carpal tunnel usually are subject to frequent use of their wrists demanded by their jobs or lifestyle and thus often find wrist splints uncomfortable and restricting of daily activities. Other nonsurgical prevention products have not been proven to work and in many cases have shown to increase pain and numbness. Medication and drugs are ill-favored, expensive, temporary and cumbersome to obtain and use to treat constant pain. Surgical treatment at many times is also a very nonattractive solution as it is time-consuming, painful, and expensive. Carpal tunnel patients in use of wheelchairs often find electric wheelchairs expensive and unnecessary to treat their wrist problems. There is a very wide variety of wrist braces of varying material and function. Most braces today aim to make their product comfortable, washable, durable, and easy to remove while holding the wrist firm and stable. Wrist braces are the most sought solution to carpal tunnel and a large variety with prices ranging from $10 - $200+ are available in pharmacies, grocery stores, hospitals, and online. A doctor would provide an inexpensive wrist splint upon diagnosis. Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to relieve pain and inflammation. Studies have not shown NSAIDs to be effective for carpal tunnel treatment but may reduce symptoms. Some common medicines include aspirin, ibuprofen, and naproxen. These 11 products can be readily found in grocery stores or pharmacies with respective labels. Some commercially popular drugs are listed: Aspirin: Ibuprofen: Naproxen: Tylenol Extra Strength 100 tablets - $15.99 Motrin IB (200mg) 100 caplets – $9.75 Advil (200mg) 150 caplets - $14.99 Aleve (220mg ) 100 caplets - $10.99 These drugs are commercially available and inexpensive, but are recommended to be used with a doctor’s diagnosis and may cause side effects. Surgery is sometimes recommended when other treatment has not helped, if a carpal tunnel condition has continued for a long time, or if there is nerve damage or the risk of nerve damage. This is determined by an electromyography or nerve conduction test. Surgery involves cutting the ligament that forms the roof of the carpal tunnel to relieve the pressure on the median nerve, which eases the symptoms of carpal tunnel syndrome.Surgery is usually successful. In some cases it does not completely relieve the numbness and pain in the fingers or hand. This may be the case if there has been permanent nerve damage caused by longstanding carpal tunnel syndrome or by other health problems such as diabetes. Surgery is recommended for only severe cases of carpal tunnel because of recovery and expense implicated difficulties. Cost of surgery and rehabilitation is in the range of $5,000 to $10,000 with some improvement achieved in over 70% of cases. Full restoration is achieved in less than 60% of surgeries. Downtime and rehabilitation generally range from six weeks to three months, but can take over a year, depending on how many lingering symptoms result and the degree of scar tissue formation as this primary ligament in the hand heals back together. Scar tissue formation during recovery from surgery is unpredictable and sometimes results in less space in this narrow anatomical passage of the wrist after the carpal tunnel surgical procedure, causing even more discomfort and numbness after surgery. This complication is only reported in less than 15% of surgical procedures. It is common for people recovering from the carpal tunnel surgical procedure to experience some permanent loss of grip strength, a perduring loss of lifting strength in the wrist/forearm, a nagging loss of full range of motion of the hand and wrist after surgery and lingering tenderness at the incision. B1. CARPAL T UNNEL S YNDROME - T REATMENT O VERVIEW The goal of treatment for carpal tunnel syndrome is to allow you to return to your normal function and activities and to: Address other health conditions if they are making your symptoms of carpal tunnel syndrome worse. Reduce any inflammation of tissues in the wrist that puts pressure on the median nerve. Determine the causes of your carpal tunnel symptoms. You can then identify whether there are activities for you to avoid or do differently and ways you can help prevent the condition. Prevent nerve damage and loss of muscle strength in your fingers and hand. 12 Treatment for carpal tunnel syndrome is based on the seriousness of the condition, whether there is any nerve damage, and whether other treatment has helped. Treatment options include treatment without surgery (nonsurgical treatment) or with surgery. If treated early, carpal tunnel symptoms usually go away with nonsurgical treatment. If your symptoms are mild, with occasional tingling, numbness, weakness, or pain, 1 to 2 weeks of home treatment are likely to relieve your symptoms. If home treatment does not help, or if your symptoms are more severe (including the loss of feeling in your fingers or hand, or the inability to perform simple hand movements such as holding objects or pinching), have your doctor examine you and recommend treatment. i) N ONSURGICAL T REATMENT If your symptoms are not severe, expect your doctor to recommend nonsurgical treatment to see whether symptoms improve. Nonsurgical treatment includes: Evaluating any other medical problems that might contribute to carpal tunnel syndrome, and changing your treatment for those problems if needed. Changing or avoiding activities that may be causing symptoms, and taking frequent breaks from repetitive tasks. Wearing a wrist splint to keep your wrist straight, usually just at night. See a picture of a wrist splint. Using nonsteroidal anti-inflammatory drugs (NSAIDs) to relieve pain and reduce inflammation. Although studies have not shown NSAIDs to be effective for carpal tunnel syndrome, they may help relieve your symptoms. Learning ways to protect your joints as you go through your daily activities. In some cases, oral corticosteroids or corticosteroid injections into the carpal tunnel may be considered if other methods to reduce inflammation do not work. ii) S URGICAL TREATMENT Surgery is sometimes recommended when other treatment has not helped, if a carpal tunnel condition has continued for a long time, or if there is nerve damage or the risk of nerve damage. Surgery involves cutting the ligament that forms the roof of the carpal tunnel. This relieves the pressure on the median nerve, which eases or ends the symptoms of carpal tunnel syndrome. Surgery is usually successful. In some cases it does not completely relieve the numbness and pain in the fingers or hand. This may be the case if there has been permanent nerve damage caused by long-standing carpal tunnel syndrome or by other health problems such as diabetes. 13 B2. S UMMARY Nonsurgical treatment Changing or avoiding activities that may be causing symptoms, and taking frequent breaks from repetitive tasks. Wearing a wrist splint to keep your wrist straight, usually just at night. Using nonsteroidal anti-inflammatory drugs (NSAIDs) to relieve pain and reduce inflammation. Although studies have not shown NSAIDs to be effective for carpal tunnel syndrome, they may help relieve your symptoms. A wrist splint is a brace that looks like a fingerless glove and that stabilizes your wrist in a straight and sometimes slightly bent-back position. Wearing a wrist splint minimizes pressure on the median nerve and allows you a period of "relative rest" from movements that make carpal tunnel syndrome worse. ** nonsurgical treatments usually treat only symptoms and not the source; also for non-severe cases Surgical treatment Surgery is sometimes recommended when other treatment has not helped, if a carpal tunnel condition has continued for a long time, or if there is nerve damage or the risk of nerve damage. Surgery involves cutting the ligament that forms the roof of the carpal tunnel. This relieves the pressure on the median nerve, which eases or ends the symptoms of carpal tunnel syndrome. **Surgery is usually successful. In some cases it does not completely relieve the numbness and pain in the fingers or hand. This may be the case if there has been permanent nerve damage caused by long-standing carpal tunnel syndrome A. WRIST SPLINTS Wrist splints can keep the wrist from bending. They are not as beneficial as surgery for patients with moderate-to-severe CTS, but they appear to be helpful in specific patients, such as those with mild-to-moderate nighttime symptoms of less than a year's duration. In selected patients, up to 80% reported fewer symptoms, usually within days of wearing the splint. 14 Typically the splint is worn at night or during sports. The splint is used for several weeks or months, depending on the severity of the problem, and may be combined with hand and finger exercises. Benefits may last even after the patient stops wearing the splint. B. CORTICOSTEROIDS Corticosteroid Injections Corticosteroids (also called steroids) reduce inflammation. If restriction of activities and the use of painkillers are unsuccessful, the doctor may inject a corticosteroid into the carpal tunnel. Some experts recommend them for patients with CTS whose symptoms are intermittent, and there is no evidence of a permanent injury. In CTS, steroid injections (such as cortisone or prednisolone) shrink the swollen tissues and relieve pressure on the nerve. Evidence strongly suggests that they offer short-term relief in a majority of CTS patients. It should be noted that the pain may increase for a day or two after the injection, and skin color may change. Unfortunately, in many cases, steroid injections provide only temporary relief (from 1 - 6 months), particularly in patients with more severe symptoms. Generally a second injection does not provide any added benefit. Another concern with use of these injections in moderate or severe disease is that nerve damage may occur even while symptoms are improving. Corticosteroid injections are particularly useful for pregnant patients, as their symptoms often go away within 6 - 12 months after pregnancy. Most doctors limit steroid injections to about three per year, since they can cause complications, such as weakened or ruptured tendons, nerve irritation, or more widespread side effects. Low-Dose Oral Corticosteroid Oral corticosteroids are medicines taken by mouth. Short-term (1 - 2 weeks), low-dose use of corticosteroids may provide long-term relief, but long-term use can cause serious side effects, including high blood pressure and high blood sugar levels. People with diabetes should be very cautious about oral corticosteroids. C. ULTRASOUND Ultrasound employs high-frequency sound waves directed toward the inflamed area. The sound waves are converted into heat in the deep tissues of the hand, opening the blood vessels and allowing oxygen to be delivered to the injured tissue. It is often performed along with nerve and tendon exercises. It is not yet known how effective ultrasound treatment is. D. NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) 15 Nonsteroidal anti-inflammatory drugs (NSAIDs), which include aspirin and ibuprofen (Advil), are the most common pain relievers used for CTS. They block prostaglandins, the substances that dilate blood vessels and cause inflammation and pain. Unfortunately, as with most other medications used for carpal tunnel syndrome, there are few wellconducted studies to determine their role in CTS. To date, there is no evidence that they offer any significant relief, and regular use can have serious side effects. Therefore, they are generally not used for long-term treatment of carpal tunnel symptoms. E. OTHER CONSERVATIVE APPROACHES Ice and Warmth Ice may provide benefit for acute pain. Some patients have reported that alternating warm and cold soaks have been beneficial. (If hot applications relieve pain, most likely the problem is not caused by CTS but by another condition producing similar symptoms.) Low-Level Laser Therapy. Some investigators are working with low-level laser therapy (LLLT), which generates extremely pure light in a single wavelength. The procedure is painless. Two trials comparing laser therapy to conservative treatment or a placebo laser treatment from no real benefit for this therapy. F. ALTERNATIVE THERAPIES Many alternative therapies are offered to sufferers of carpal tunnel syndrome and other repetitive stress disorders. Few, however, have any proven benefit. People should carefully educate themselves about how alternative therapies may interact with other medications or impact other medical conditions, and should check with their doctor before trying any of them. Vitamin B6 Vitamin B6 (pyridoxine) is often used for carpal tunnel syndrome. Studies have not supported its benefits, however, either in oral or cream form. It should also be noted that excessively high doses of vitamin B6 can be toxic and cause nerve damage. Acupuncture A very limited amount of evidence shows that acupuncture may be useful as a supplement to standard treatment. Chiropractic Therapies 16 Chiropractic techniques have been useful for some people whose condition is produced by pinched nerves. There is little evidence, however, to support its use for carpal tunnel syndrome. Magnets Magnets are a popular but unproven therapy for pain relief. Botulinum toxin type A Intracarpal injections of botulinum toxin type A (Botox) has not been well studied. G. ELECTRIC WHEELCHAIRS Electric wheelchairs are easy to use and would restrict the necessary wrist movement needed to move on a normal wheelchair and prevent/treat carpal tunnel.There are a wide variety of electric wheelchairs available, however even the most inexpensive wheelchairs are in the price range of $1000+. For our specific consumer target, long-term wheelchair users with high risk of developing carpal tunnel, the electric wheelchair is a solution closest to our goals, but we are also trying to make our product inexpensive and readily available. The wrist splint and electric wheelchair tackle similar goals to restrict wrist movement to prevent carpal tunnel. More specifically relevant products include the Slayer Wheel and the Smart Wheel. H. OTHER INNOVATIONS SmartWheel Wheelchair prescription is complex with thousands of choices and options. Theoretically, a higher quality or innovative wheelchair that is appropriately matched to the user and their unique needs will increase participation. It is well accepted that there is an alarmingly high incidence of carpal tunnel syndrome, and rotator cuff injuries among manual wheelchair users. Since the initial conceptualization, the SMARTWheel was intended to better understand the physiological and physical effects of wheelchair propulsion on the body. Initially, little was known about wheelchair propulsion and the SMARTWheel transformed the nascent field of wheelchair propulsion biomechanics. 17 Although still an important area of clinical research, the SMARTWheel has been critical to the study of the relationship between the type of wheelchair, set-up, activity, technique, anatomy, and physiology and repetitive strain injury. There has been growing evidence that the wheelchair-user interaction explains a substantial portion of the risk of developing a degenerative injury and on community participation. A noteworthy contribution of this work was the release of the clinical practice guideline, entitled, Preservation of Upper Limb Function Following Spinal Cord Injury in 2005. The SMARTWheel has been used by other scientists in areas that were not originally envisioned to be applications. It has been used to support the design of tools for developing a trail mapping rating and description system. It has also supported the design of accessible pedestrian walkways standards, accessible playground surfaces, and to evaluate carpets for wheelchair accessibility. It is likely that there are more new areas of exploration to emerge. This article describes the evolution of the SMARTWheel as new technologies became available and its applications in the field of wheelchair biomechanics and clinical service delivery. SmartWheel Homepage 18 RODEM 19 A new competition in the fast-moving field of slow-moving mobility -- at least if this new RODEM prototype developed by a group of research partners at Japan's Veda Center (including Tmsuk) actually hits the market. Apparently designed to be used as both a replacement for a wheelchair and as a general purpose "universal vehicle," the four-wheeled RODEM allows folks to simply lean forward slightly without the need for any back support, which the group says will let people get in and out of the vehicle more easily, and with less assistance from caregivers. Of course, no sci-fi inspired vehicle would be complete without a few bells and whistles, and it looks like the RODEM is more than capable in that department, with it packing some built-in GPS, automatic obstacle evasion control, automatic slope correction, an "autonomous navigation function," voice recognition, and some sort of vital monitoring system (all of which may or may not actually be included in the prototype). SlayerWheel Over 70% of manual wheelchair users will suffer from shoulder pain or carpal tunnel syndrome in their lifetime. Choosing a lightweight wheelchair wheel and ergonomic handrim can significantly reduce this risk and lead to a better quality of life for the user and their carers. Over the last 30 years there have been significant advances in wheelchair wheel and wheelchair hand rim design research that indicates that there are significant pain relieving advantages that can be enjoyed by choosing lightweight wheelchair wheels and ergonomic wheelchair hand rims. In addition incorporating rear wheel and castor suspension not only makes the wheelchair easier to propel, but makes the ride smoother and reduces the probability of secondary neck pain, lowback pain and abdominal discomfort. 20 C. Patents Wheelchair Drive Mechanism Patent number: 6,893,035 Title: Wheelchair drive mechanism 21 22 23 Manually Propelled Wheelchair Device Patent number: 5,941,547 Title: Manually propelled wheelchair device 24 25 Wheelchair Drive System with Level Propulsuion Patent number: 7,837,210 Title: Wheelchair drive system with lever propulsion and a hub-contained transmission 26 27 Wheelchair Drive Mechanism 2 Patent number: 7,261,309 Title: Wheelchair drive mechanism 28 29 30 Conversion Kit for Manual Wheelchairs Patent number: 6,371,502 Title: Universal conversion kit for human powered wheelchairs 31 32 Propulsion Aid Patent Number: 6,048,292 Title: Combination arm exercise apparatus and propulsion aid for a wheelchair 33 Wheelchair-Attachable Power Unit Patent number: 5,135,063 Title: Power unit for driving manually-operated wheelchair 34 35 Pedal Propulsion Wheelchair Patent Number: 4,560,181 Title: Wheelchair operated by hand pedalled reciprocating motion 36 37 38 D. Interviews Interview with Daliya Female student, 11-year manual wheelchair user Maneuvering is a 4 in comfort, 3 uphill Wrist pain while maneuvering Uphills are very strenuating and difficult to go up During downhill, hands stay on the pushrim for better control, but much strain Can go for like 30/40 minutes before wrist pain Uses football receiver gloves Problems? o front wheel dirt collecting, snow wheels, slippery wheels, wet wheelchair, umbrella, snow, weight, balance Why not use an electrical wheelchair? o Mechanical wheelchairs are foldable, smaller, and you can go faster Electrical wheelchairs are better for uphill, one hand is free to hold beverages, and battery life is iffy though Ace bandage wrap helps, bubble wrap thing helps, heating pad when not in use helps Willing to pay 500-1000 more Interview with Chris Baswell Contact: [email protected] Gender: Male Age: in 50s -manual wheelchair user -says he experiences no pain in the wrist; range of wrist movement during maneuvering is very minimal -says the problem is more with fingers than wrist; problem with gripping the wheel -says he has developed arthritis in his finger joints due to maneuvering wheelchair; red arrows in the following diagram show locations of his arthritis: 39 -says fatigue in his muscles(biceps and triceps) is the main reason he has to stop occasionally -reasons for not using power wheelchair: *lack of exercise; muscle atrophy -> says that most doctors won’t prescribe the patient to a power wheelchair unless it is absolutely necessary *mobility: his mechanical wheelchair is very light and the wheels come off so that it can easily fit in the trunk of a car when he needs to travel by car. However, power wheel chairs are a lot heavier and harder to transport. My idea after conducting the interview (Han) : Combination of mechanical and electrical input -model that still needs mechanical input but assists with electrical power -model that can switch between mechanical propulsion and electrical propulsion *model that harnesses energy from the mechanical input of the user into electrical, and allows the user to propel the wheelchair with the built up or created electrical energy when the user gets tired or is going up a slope. Interview with Brendan Email: [email protected] Gender: Male Age: N/A -has been using a manual wheelchair for 15 years -lives around Columbia; 106th and Broadway -wants to be active in our project -gave an 8 out of 10 on the comfort level for maneuvering the wheelchair; his reason for the score was that he has actually never thought of another way of maneuvering the wheelchair since he has been using the wheelchair for 15 years. -when asked what he thinks could be improved about the manual wheelchair, he said it was a difficult question for him to answer because it would be like asking myself what could be improved about my shoes. -said upper body muscle fatigue is what usually requires him to stop occasionally -said he preferred the manual wheelchair over the electric wheelchair due to better mobility -said he has never seen anyone use a lever type mechanism for propelling the wheelchair, nor any other interface that differs from the standard. 40 III Design Functional Requirements and Constraints 41 i. Functional Requirements Allow user to effectively steer the wheelchair Allow user to effectively operate the wheelchair with the device Reduce the incidence of upper body wheelchair related injuries Must reduce fatigue experienced by the user Must retain the original motion Wheelchair users are comfortable with the original motion and should have the option to fall back on it when desired Reduce the likelihood/effects of carpal tunnel syndrome In the study done by Sie et al., 66% of wheelchair users examined had CTS symptoms (Archives of Physical Medicine and Rehabilitation, 1992). Reduce strain on the user’s wrist Fingertip loading, the way users ambulate the wheelchair, increasespressure in the carpal tunnel (Pinkham, Occupational Health and Safety, 1988). Coast The wheelchair must be able to go forward without continuous propulsion to prevent fatigue, much like standard wheelchairs or bikes operate ii. Specifications Less than 15° of flexion and extension, less than 5° radial deviation, less than 10° ulnar deviation iii. Constraints 1 Discrete A chief concern among surveyed wheelchair users is that any wheelchair that deviates from the standard motion will attract a lot of attention. They feel like they get enough attention as it is with wheelchairs, so discretion is key to avoid feelings of self-consciousness and discomfort. Portable Light-weight Not biomechanically taxing Young male paraplegics have been observed to expend 9.9 calories per minute when pushing a hard pace of four to five miles per hour (Trotter, 1985).1 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2327379/pdf/canfamphys00210-0053.pdf 42 2 3 Affordable Low levels of educational attainment and low employment rates combine to create a bleak economic picture for many wheelchair users, one-fifth (19.1 percent) of whom live in poverty. Wheelchair use decreases by nearly a factor of 5 between persons with family income less than $10,000 (1.3 percent of whom are wheelchair users) and those with family income greater than $35,000 (0.3 percent) (Kaye et. Al, 2002).2 Easy to use For patients with quadriplegia who have reduced hand dexterity,the wheelchair must allow the user to use only one hand to operate it. Also, wheelchair users tend to get injured from transferring from the wheelchair to another surface, propelling a wheelchair, and unweighting the sacrum with improper form.3 Adjustable Wheelchair users come in a variety of body types, and our design must be able to accommodate them Bidirectional The device should provide propulsion in both forward and backward directions, to make use of all of the muscle groups in the upper body to reduce overall fatigue http://dsc.ucsf.edu/publication.php http://www.ncpad.org/ 43 IV Preliminary Designs 44 i. Upper Body Pull ii. 45 Degree Slide 45 iii. Elliptical iv. Rim Slide v. Tank 46 vi. Hand Bike vii. Ski Bike viii. Grip 47 ix. Backward Wheel x. Wrist Brace xi. Skateboard 48 VI Design Matrix 49 Concept Selection Matrix CRITERIA minimize wrist strain sustainable motion Max Power stable arm position flat land balance slope balance 0 Pushrim (standard) WEIGHT Value 100 500 85 30 85 70 45 totals: 0 Crew 0 Ski 0 Elliptical U. Arm Push Value 5 700 Value 7 800 Value 8 1000 10 1000 425 150 425 350 225 5 5 5 5 5 5 9 8 5 3 4 6 7 6 3 2075 30 425 270 680 350 135 340 180 595 420 135 595 7 120 4 850 10 560 8 180 4 595 90 510 630 90 2560 37 2470 34 3305 43 2915 45 degree Vert Push 10 800 8 700 7 7 3 6 9 2 510 150 765 560 450 6 5 9 8 10 425 270 510 630 225 5 9 6 9 5 37 3235 46 2760 41 Note: This decision matrix was designed to select the best motion for the manual wheelchair user to use to propel the wheelchair. Once the type of motion was selected, the mechanism for the motion could then be specified. 50 VI Proof of Concept Plan 51 i. Measuring the Range of Wrist Movement Carpal tunnel syndrome(CTS) is one of the notablediseases that manual wheelchair users develop; 54% of users at 1-10 years of chair use develop this disease and 90% at 20-30 years.4 With our design we intend to reduce this high incidence of CTS within the manual wheelchair population. Carpel tunnel syndrome has been proven to be correlated to an elevation in pressure in the carpal tunnel, specifically an impingement of the median nerve that runs through the carpal tunnel in the wrist. Gellman et al. have shown that an elevation of pressure is directly proportional to joint angle. Using exercise machines that closely mimic arm motions used in our preliminary designs, the range of radial and ulnar deviation and of flexion and extension of the wrist will be measured then compared among the different arm motions as well as compared to the motion of operating a manual wheelchair. In this way, the magnitude of the wrist angle ranges will be used as a proxy for intensity of median nerve impingement and consequentlyrisk of carpal tunnel syndrome. ii. Measuring EMG Signals from Various Upper Body Muscle Groups at Different Angles of Motion The next steps of our proof of concept will involve going to the fitness center with our EMG detector, electrodes, and oscilloscope, and measuring EMG signals from various upper body muscle groups at different angles of motion. The motion used for propulsion will be simulated by the use of a cable machine(Figure 1), and the experimenter will be seated on a chair to mimic the conditions of a wheelchair user. Refer to Figure 2 for a picture of the setup used for the experiment. Through the following procedures, we hope to determine the most ideal angle at which the user of our device would have to input the necessary force for propulsion(refer to Figure 3), and the most ideal angle at which the normal vector to the plane of the palm of the hand(refer to Figure 4) would be positioned when applying the necessary force for propulsion; the most ideal angle will be determined by the most even muscle activation between the various muscle groups with consideration of relatively how much stress each muscle can handle. The procedure is laid out below: 1) By adjusting the height of the handle on the cable machine, the angle of the cable with respect to the vertical can be varied(Figure 3). Start with this angle set at 90°. 2) When grabbing the handle of the cable machine, make sure that the normal vector to the plane of the palm(Figure 4) is facing up at 0° with respect to the vertical. 3) Place two electrodes on the biceps and one electrode on the elbow to set as ground. Connect the output of the EMG detector to an oscilloscope, and set the scope at the appropriate settings to measure the EMG voltage waves. 4) Carry out the push/pull motion on the cable machine at least 10 times and record the amplitudes of the voltage wave for each cycle. 4 http://www.ncpad.org/exercise/fact_sheet.php?sheet=109&view=all 52 5) Repeat steps 3-4 for the two electrodes placed on the triceps, front deltoids, back deltoids, pectoralis major, and trapezius. 6) By adjusting the height of the handle on the cable machine, set the angle of the cable with respect to the vertical at 65° and repeat steps 2-5. Repeat steps 2-5 for angles of 45°, and 25° 7) When grabbing the handle of the cable machine, make sure that the normal vector to the plane of the palm is directed at 20° with respect to the vertical, and repeat steps 1, 3-6. Vary the angles of this normal vector in intervals of 20°, until the palm of the hand is facing down at 180° with respect to the vertical. 8) Make tables and graphs from the data and analyze the muscle activation of the various muscles groups for the different variables considered. Figure 1. Cable Machine Figure 3. Angle of the cable with respect to the vertical Figure 2. Picture of set-up used for experiment Figure 4. Angle of normal vector to the plane of the palm with respect to the vertical 53 VII Proof of Concept Outcome 54 i. Measuring the Range of Wrist Movement Wrist joint angles are directly proportional to the elevation of pressure in the carpal tunnel. Repeated and prolonged exposure to large pressures (>30 mm Hg) within the tunnel and thereby large joint angles of the wrist induces carpal tunnel syndrome. In order to determine what arm motions will reduce the severity of carpal tunnel syndrome within the wheelchair population, an experiment was carried out to determine the range of wrist angles a person experiences while operating various exercise machines that mimic the arm motions proposed in preliminary designs of our product. On the left arm of a 21 year-old able-bodied woman, black dots were drawnon the right side andthe middle of the top of the wrist, the right side and the middle of the top of the forearm, just below the third knuckle of the middle finger, and finally on the right side of the handby the third knuckle of the pointer finger (6 dots total), see Figure 1.The exercise machines used in this experiment were a Precor Chest Press, a PrecorLongpull Modular Station, and a Concept2 Indoor Rower, see Figure 2. A manual wheelchair was used as the control.Prior to using each machine, pictures of the front and side views of the left arm in a neutral position were taken. While the subject operated each machine, pictures of the front and side views of the left arm were taken intermittently. The pictures were then analyzed usingImageJ;using the three dots seen in each view, the angle tool was used to determine the angle ofradial deviation(RD), ulnar deviation (UD), flexion(Flex) and extension(Ext), see Figure 3. For each measurement, three different individuals measured the angle. These three trials were then averaged. With reference to the neutral position of the wrist, the range of the angles experienced by the wristwascalculated for each machine as well as the maximum range of the wrist itself, see Table 1. Employing almost the full range of motion of the wrist, the machine with the largest range was the manual wheelchair, underscoring a user’s high risk of developing carpal tunnel. For the Longpull Modular Station, the maximum radial deviation and ulnar deviation is smaller than that for the wheelchair; however, the amount of flexion and extension is significantly higher compared to the ChestPress and the Longpull Modular Station. The main difference between the motion when using the Indoor Rower and the Longpull Modular Station is that when usingthe Indoor Rower, a user’s elbows stay away from the torso; this results in decreased wrist flexion. The Chest Press has the lowest range of wrist joint angles. The main difference between the motion when using the Indoor Rower and the Chest Press is that when using the Chest Press, a user’s palms are facing each other rather than be parallel to the ground and that a user’s elbows remain close to the torso. These results support our design, to have the motion of the arm include keeping a user’s elbows close to their torso and having their palms face each other. Figure 1. Sample Images of Marker Placement on Subject’s Hand 55 Figure 2. Exercise Machines Used In This Experiment5678 Figure 3.Image Representation of Radial Deviation, Ulnar Deviation, Wrist Flexion and Extension9 5 http://www.precor.com/products/en/commercial/strength/experience-strength-s-line/upper-body/chest-press-c001es http://www.precor.com/products/en/commercial/strength/icarian-strength/multi-station-and-modulars/longpullmodular-station 7 http://www.concept2.com/us/default.asp 8 http://www.lighthousedme.com/products/wheelchairs.html 9 http://tt.tennis-warehouse.com/showthread.php?t=337194&page=3 6 56 Neutral RD UD (degrees) (degrees) (degrees) Maximum Range of Wrist Wheelchair avg. Chest Press avg. Indoor Rower avg. Longpull Modular Station avg. Neutral Ext (degrees) (degrees) Flex (degrees) 75.42 60.35 30.25 -20.77 177.95 178.86 177.95 178.25 150.03 149.12 149.4 149.52 185.94 184.36 185.22 185.17 182.34 181.22 181.93 181.83 153.35 154.73 153.32 153.80 191.51 191.43 192.48 191.81 0 28.74 6.92 0 28.03 9.98 178.22 177.98 178.13 178.11 174.32 173.5 174.06 173.96 184.31 183.6 183.94 183.95 181.37 182.16 181.56 181.70 172.65 174.59 173.66 173.63 180.36 179.83 180.77 180.32 0 4.15 5.84 0 8.06 1.38 176.39 177.21 177.93 177.18 173.55 173.2 173.34 173.36 183.43 182.7 182.95 183.03 180.95 181.4 181.35 181.23 168.54 167.49 168.7922 168.27 181.48 182.58 182.4 182.15 0 3.81 5.85 0 12.96 0.92 178.57 172.58 182.75 181.82 170.67 198.49 177.95 177.11 177.88 171.74 172.61 172.31 183.49 183.03 183.09 181.49 180.02 181.11 169.65 171.33 170.55 199.4 198.15 198.68 0 5.57 5.21 0 10.56 17.57 Table 1. Summary of Data and Calculations 57 ii. Measuring EMG Signals from Various Upper Body Muscle Groups at Different Angles of Motion The graphs below display the results of the experiment. By measuring the degree of muscle activation of each muscle at the different angles of motion, relative stress distributions to the various muscles at each angle can be inferred. Generally, it can be seen that the degree of activation of the biceps stays fairly constant throughout the different angles, and that the stress from the back and front deltoids and trapezius are gradually transferred to the triceps and pectoralis major as the angle is increased starting from 0 degrees. 65 degrees was eliminated as the most ideal angle from the start because it distributed most of the stress to only the triceps and pectoralis major. Upon further observation, it can be seen that the motions at 0 and 25 degrees have the most even muscle activations of the different muscles used. It can be concluded that 25 degrees below the horizontal is the most ideal angle of motion because the pectoralis can handle greater stress than the front deltoids. The next steps will involve testing more angles between 0 and 25 degrees, using a pull motion instead of a push motion, and testing angle at which the normal vector to the plane of the palm of the hand would be positioned when applying the necessary force for propulsion. Figure 4. Results of the 2nd proof of concept experiment