MENG 491W Fall 2008

MENG 491W Senior Design Project I

Pain Relief Glove for Spasticity

Spencer Anderson, Matt Arnold, Vincent Atofau, Sergio Valdez

Table of Contents

1. Context

1.1. Background of Need

1.2. Customer Need Statement

1.3. Literature Review

1.3.1. Prior Work

1.3.2. Patents

2. Problem Definition

2.1. Customer Requirements

2.1.1. Form

2.1.1. Fit

2.1.2. Function

2.2. Assumptions

2.3. Constraints

2.4. Customer Requirements Schematic

2.5. Test/Evaluation Plan for all Requirements and Constraints

3. Concept Development

3.1. Overview

3.1.1. Creative Strategies

3.1.2. Governing Principles

3.2. Synthesis and Analysis of Overall Concept

3.2.1. Lever and Brace

3.2.2. Pulley and Air Pump

3.2.3. Pulley and Springs

3.2.4. Pulley and Motor

3.3. Evaluation

3.4. Refinements

3.5. Selection

4. Design Specifications

4.1. Design Overview

4.1.1. Description

4.1.2. Design Schematics

4.2. Functional Specifications

4.3. Physical Specifications

4.4. Product QFD

4.5. Subsystems

4.6. Design Deliverables

5. Project Plan

5.1. Research

5.2. Critical Function Prototypes

5.3. Design

5.4. Construction

5.5. Testing

5.6. Project Deliverables

5.7. Schedule

5.8. Budget

5.9. Personnel

6. References

7. Appendices

7.1. Team Member Resumes

List of Figures

Figure 1: Hand Anatomy (

Figure 2: Customer Requirement Schematic for glove

Figure 3: Lever and Brace Force Analysis

Figure 4: System Schematic for Pain Relief Glove

Figure 5: Function Schematic for Pain Relief Glove

Figure 6: Process Schematic for Pain Relief Glove

Figure 7: Drawing

Figure 8: Gantt Chart

Figure 9: Organization Chart for Pain Relief Glove

List of Tables

Table 1: Hand Grip Strength Test

Table 2: Kepner-Tregoe Analysis for Pain Relief Glove

Table 3: Product QFD Matrix for Pain Relief Glove

Table 4: Schedule

Table 5: Budget for Pain Relief Glove

1. Context

1.1. Background of Need

A stroke typically is caused by hemorrhaging or a lack of blood supply to a localized region of the brain. The affected area is usually contained in one side of the brain. Therefore, the neurological damage only affects the muscles on the opposite side of the body. One of the many symptoms that last long after immediate recovery from a stroke is spasticity. After a stroke occurs, the muscles in the victim’s arm may become contracted constantly, disabling their hand from opening(Spasticity After Stroke). This results in the individual creating a fist. In other cases, spasms can occur frequently, leading toextreme painin the joints and muscle damage. The condition can also seriously hinder the victim’s daily routines. If the hand is not opened periodically, disfiguration can occur. Many spasticity attacks can happen at night, causing discomfort as well as loss of sleep.

A Columbia-Presbyterian Medical Center study also shows that a connection between a person’s body mass index and their chances of stroke has not been found. Instead, there waist-to-hip (WHR) ratio is a better predictor of stroke. A greater WHR means there is a greater chance of a person having a stroke than a person with a lower WHR (Siddiqui 2008). Another study by the Department of Neurology, Liaquat National Hospital, shows that females are just as likely as males to have a stroke. Also, most stroke victims are an average age of 60 years old and therefore past the peak of their physical strength (AmericanAcademy Of Neurology). Therefore, the stroke survivors most likely have poor strength compared to an average adult. Table 1 shows a hand strength test for adults, in which it is assumed that most stroke victims would score in the poor or very poor categories, giving them an average hand grip strength of about 30kg before their stroke. It is assumed that the stroke survivors will become much weaker after they suffer the stroke as well. Also, although spasticity does contract the muscles in the hand, it is believed that this will not cause the hand to close at its full capacity shown by the hand grip strength test. The patient will not be clenching their fist as hard as they can. Therefore, it is more likely that a stroke survivor suffering from hand spasticity will keep their hand closed with a force of about 20 lbs.

There are numerous ways in which spasticity can be relieved, with varying ranges of cost and effectiveness. One of the newest and most successful methods is the insertion of Botox into the patient’s hand. However, this is very expensive, and it is not always convenient. There is limited time that a Botox treatment is effective before it wears off. Because of this, the patient will never be able to fully recover from the stroke and will spend large amounts of money in an attempt to do so. Another past solution to the problem is the use of dynamic hand splints, which are used in many nursing homes and hospitals.

Table 1: Hand Grip Strength Test

rating*
/
males (kg)
/
females (kg)
Excellent / > 64 / > 38
very good / 56-64 / 34-38
above average / 52-56 / 30-34
average / 48-52 / 26-30
below average / 44-48 / 22-26
poor / 40-44 / 20-22
very poor / < 40 / < 20

* source and population group unknown

Aides at hospitals and nursing homes often have many ways of dealing with spasticity. Depending on the strength and frailty of the patient, some aides are able to open spastic hands by sheer brute force. There are other times when this is not possible. One of the simple and effective tools used by hospital staff to combat spasticity in patients is the cone. Many times an aide will place the small end of the cone in between the metacarpal bones of the thumb and curled fingers (Figure 1) of a patient’s hand. They then force the cone slowly through the fist until the hand is opened. This seemingly primitive method is actually used quite frequently by aides. There is a need for a way to open the hand without an aide,giving the stroke victim more independence from medical professionals.

Figure 1: Hand Anatomy (

1.2. Customer Need Statement

The primary customers of this project are stroke survivors that suffer from the post-stroke symptom of hand spasticity. The assumed customers are those suffering from spasticity in one of their hands. Typically, a nurse or aide is needed to help patients stretch their hand to an opened position. A device that assists in the opening and closing of the hand without an aide is needed to remedy the pain caused by spasticity. Frequently, spasticity attacks occur at night when aides are not readily available. Accordingly, the device would be used primarily at night and would be designed to be worn while the patient is asleep. Addressing this need would relieve pain and save the customer the money needed to employ a part-time aide, while improving their independence.

1.3. Literature Review

1.3.1. Prior Work

Many patients with spasticity have resorted to Botox injections to help relieve the pain they get from their day to day muscle spasms. “Botox (Botulinum toxin)… relaxes muscles by blocking the release of the neurotransmitter, acetylcholine, which triggers muscles, prompts excitability, arousal, and reward, and activates learning and short-term memory. A small dose of Botox injected directly into the spastic muscle(s) blocks the acetylcholine so that the muscle can loosen and relax, resulting in increased flexibility and mobility and reduced pain” (South Nassau Communities Hospital).

The results of the drug can come into effect within the first week of usage. For some, the drug works well in relieving the pain, however, some patients found negative results. “Localized pain, tenderness, and/or bruising may be associated with the injection” (Botox). Also the Botox injections have been known to worsen many medical conditions.

Many patients have also looked to strengthening the muscles in opening the hands. “One of the exercises against repetitive strain syndrome is to exercise the muscles that open the hands,” says Jolie Bookspan, M.Ed, PhD, FAWM. However it still doesn’t help open the hands when in a spasm.

1.3.2. Patents

Many patents have been filed for devices that try to solve the problem of hand spasticity. The following patents solve parts of the problem, but leave much room for improvement:

  • Articulated hand splint with multiple pivot points-Rudolph H. Bodine(4660550)
  • Articulated hand splint with a frame around the arm connected by a pivot at the wrist to a hand grip housing. A therapist can set the device to two or more positions.
  • This device only allows for movement in the wrist. The fingers are always clasped around the hand grip, so the hand is not opened by the device. Also, a therapist is required to adjust the device.
  • Universal articulated splint-Rose DeProspero(4719906)
  • Articulated hand splint with pivots at every finger joint. The wrist and each finger are supported and can be bent and locked into place or provide resistance for exercise.
  • There is no mechanism to aid in the opening of the hand. The hand must be opened joint by joint and locked into position by an aide. The glove is primarily for the rehabilitation of a weak hand as opposed to relieving pain caused by a spastic hand, although the patent mentions the glove could be used for a hand affected by spasticity.
  • Device for and method of dynamic splinting-Krister Silfverskiold(4790301)
  • Dynamic hand splinting device that uses a line attached to a finger support and wrapped around a spool to provide the force needed to straighten the fingers. The spool is anchored to a fastening plate for stability.
  • The power input to straighten the fingers is not explained well. A spring is used to raise the finger, but it is unclear how.

2. Problem Definition

2.1. Customer Requirements

The customer requirements are broken up into the three categories of form, fit, and function and rated on a scale of 1-5 with 5 being the most important. The glove should:

2.1.1. Form

  1. Weigh less than3 lbs.3
  2. Be custom fit according to users’ hand (normal hand size). 1
  3. Be made of a strong, durable material.5

2.1.1. Fit

  1. Support the four fingers. 5
  2. Support the thumb.2
  3. Be simple to use3
  4. Fit comfortably on the patients’ hand.3

2.1.2. Function

  1. Open a patients’ clenched hand and keep it open for an extended period of time. 5
  2. Be able to lock in the opened position, supporting upwards of 20lbs of force.4
  3. Be operable by the customer alone, without an aide.4
  4. Have good ventilation and be washable.1
  5. Not interfere with sleep patterns. 2
  6. Provide some resistance when slowly reclosing the patients’ hand. 2

2.2. Assumptions

The assumptions are as follows:

  1. Customers could use a device to open their hand to improve their daily lives
  2. Spasticity normally affects one side of the body, so the other hand is healthy
  3. Customers have low hand grip strength

2.3. Constraints

The constraints are as follows:

  1. The project needs to be done in 8 months
  2. There is an $800 budget
  3. Frailty of a patients’ hand
  4. Must be quiet enough to allow for sleeping (under 70 decibels)
  5. Must abide by the Universal Medical Device Code

2.4. Customer Requirements Schematic

The customer requirements schematic is shown below in Figure 1:

Figure 2: Customer Requirement Schematic for glove

2.5. Test/Evaluation Plan for all Requirements and Constraints

Plans for testing the following requirements include:

  • Achieve a maximum force of 20lbs: AJamar dynamometer or similar tool will be use to measure the strength of the glove. The dynamometer will also be used to calibrate the user’s commands with the output power. The resistance will be varied to see how it affects the force the glove achieves.
  • Easy to use: Glove will be tested by letting customers use the glove and asking them questions and getting feedback of what they thought of the gloves overall performance.

3. Concept Development

3.1. Overview

3.1.1. Creative Strategies

The following creative strategies were used to generate the various designs in the development process:

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  • Sketching
  • Functional decomposition (Appendix A)
  • Role-play
  • Analogies
  • Ask a good question

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3.1.2. Governing Principles

The pain-relief glove isgoverned by the principles of Ergonomics (the safety, comfort, ease of use, productivity, and aesthetics). Potential motors would be governed by the principles of physics (how much power needed for work) and circuits (electrical uses). The pulleys are governed by principles of physics (least amount of pulleys for maximum work). The air pumps are governed by principles of physics as well (determining air pressure). The springs and cables are governed by principals of physics (determining tensions and strength in each spring and cable)

3.2. Synthesis and Analysis of Overall Concept

3.2.1. Lever and Brace

To devise the lever and brace concept we implemented strategies such as “asking a good question”, sketching, and role playing.The question that was considered was, “How can the hand of a patient be opened with the least input force?” By asking basic questions we were able to define our problem and foster multiple solutions. Role playing helped us visualize the movement of the hand. The sketching made it easier to understand how the levers could be assembled.

The lever and brace consists of two levers and two braces. The first brace would be connected to the proximal phalanges, shown in Figure 1, with the lever locked at the forearm. The second brace can be connected to the middle phalanges and lever will be locked at the forearm. The basic principal of the lever and brace is shown in figure 3.

Figure 3: Lever and Brace Force Analysis

Some of the advantages of this system are:

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  • Safe
  • No Noise
  • Low Weight
  • High Strength
  • Low Cost

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Some disadvantages are:

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  • Low Comfort/Bulky
  • Requires an Aide to Use

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3.2.2. Pulley and Air Pump

The next design used the same concept for the mechanics of opening the hand, but utilized a different power source. Instead of a motor, an air pump and pneumatic system could be used.

The Pulley and air pump concept is composed of a piston that is connected to a cable that pulls the fingers up. The piston is located on the forearm and it is pumped with a foot pump. After the user pumps the piston to full length it will be locked at the forearm. The cable is connected to a plastic plate that stands on the metacarpal bones. A block and tackle reduces the force needed to raise the fingers up. The block and tackle is connected to cables that go to the fingers.

Advantages:

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  • Safe
  • No Noise
  • Low Weight
  • High Comfort
  • Low Cost
  • Low Dependence on Aide

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Disadvantages:

  • Low Strength
  • External Pump Needed

3.2.3. Pulley and Springs

The Pulley and springs design was easier to create because we used analogies and combinations strategies. SaeboFlex makes a similar glove to the one that we want to create. Using ideas from their design and ideas from our Pulley and Pump, we came up with the Pulley and Springs.

The Pulley and Springs design is very similar to the Pulley and Pump in structure but with minor changes. Instead of using a piston and pump to provide the force, a spring will be used. The spring will still be connected to block and tackle to reduce the force needed to raise the fingers. After the block and tackle, a basic locking system will be actuated in order to keep the fingers in place over a long period of time (i.e. sleeping). Refer to Figure 5 for clarification/visualization.

Advantages:

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  • No Noise
  • Low Cost/Low Complexity
  • High Comfort
  • Low weight

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Disadvantages:

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  • Some patients may be reliant on an aide to actuate the system
  • Low Strength
  • Low Safety

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3.2.4. Pulley and Motor

Our final concept is a design to limit the dependence on an aide. We wanted a mechanism that was more user-friendly. In this design we put a motor on the forearm to provide the force needed to open the hand. With this design you will just need help in putting the glove on the hand but after that the user can be without an aide.

The components of this concept are a motor stationed on the forearm that provides the force. The motor is connected to a cable that runs through a block and tackle. The pulley is then connected to springs that are connected to distal phalanges.

Advantages:

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  • Potential to create large opening force
  • Low Dependence on Aide

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Disadvantages:

  • Low Safety
  • Low comfort
  • Excessive Noise
  • High cost
  • High Weight
  • Electric Power Necessary

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3.3. Evaluation

A Kepner-Tregoe Analysis, shown in Table 2, has been created to show the benefits and drawbacks of each design. The information presented in the decision matrix for each design is discussed below.

Table 2: Kepner-Tregoe Analysis for Pain Relief Glove

Features / Selection Criteria / Meet Codes? / 110 Volt compat. / Comfort / Ease of Operation / Safety / Noise / Cost / Weight / Overall Score
Weight Factor / Go / No / Go / No / 7 / 7 / 10 / 4 / 6 / 4
Pulley/Motor / Go / Go / 3 / 10 / 3 / 1 / 2 / 1 / 173
Pulley/ Springs / Go / Go / 4 / 5 / 3 / 5 / 4 / 4 / 497
Pulley/ Air Pump / Go / Go / 4 / 8 / 4 / 4 / 3 / 2 / 284
Lever and Brace / Go / Go / 1 / 5 / 5 / 5 / 4 / 3 / 400

Lever and Brace:

The lever and brace design could generate high force to open the hand, although there would need to be a large force put into the system in order to operate. Due to this there is a high mechanical disadvantage to this design. However, it was low cost, low noise, and fairly safe. The lever brace choice performed poorly when placed in the design matrix (Table2), most notably in the two most important categories; independence and comfort. The brace would be very bulky, thus making it uncomfortable. While the design could create a high opening force, it would require a high input force. The many weaker customers would need an aide for operation.