Sanofi Project

Concept Ideation and

Development Tuesday, April 3, 2012

Some Thoughts from Andrea

Common Causes of

Limitations in the Use of the Hands:

Age and Arthritis

Loss of Strength and Dexterity in the Hands is Common,

beginning at Age 50 – 59, and increasing in severity with

more advanced age.

With Age – Loss of strength in muscle tissue throughout

body, including the hands.

Prevalence of severe hand disability in the general

population age 50 and older is 12%, with increased

occurrence over the age of 70 and in the female gender.

Arthritis – The leading cause of disability in the United

States (Centers for Disease Control)

Age – Loss of Strength and

Dexterity

In Hand Weakness due to

Age, the Lateral Pinch Grip

weakens less than other

pinch grips.

Lateral Pinch Grip –

Example: Grip Used when

Grasping and Turning a Key.

Design to accommodate the

Lateral Pinch Grip by

making a larger contact

area for the fingers.

Osteoarthritis (OA) – caused by wear and tear

leading to deterioration of cartilage in the joints

Commonly Affected by OA:

•Distal Finger Joints

•Base of Thumb

Finger Joints Less Commonly

Affected by OA:

Middle Joints (Proximal

Interphalangeal Joints) (35%

of individuals with OA)

Base of Fingers –

(Matacarpophalangeal

Joints) (15% of individuals

with OA)

Osteoarthritis

Friction (due to cartilage deterioration) results in:

Pain

Stiffness

Swelling

Reduced Range of Motion

Pieces of Bone may break off and float within the joint

and the joint lining (synovium) and cause further

inflammation.

Rheumatoid Arthritis (RA) Unknown

Cause - Autoimmune Disease

Commonly Affects Wrist and Fingers

• Cartilage Deterioration

• Deformation of Joints

Unlike OA, Finger Joints closest to the palm of the hand (Metacarpophalangeal Joints) are commonly affected.

Phasic

o Severity Up and Down

Pain

Inflammation

Swelling

Stiffness

Reduced Range of Motion

Examples of Accommodations for OA & RA

Distal Finger Joints are used in most

Pinch and Precision Grips.

o A small pinch or other precision grip will often cause pain in the

distal finger joints with Osteoarthritis.

Make grip larger or change type of grip.

The Thumb is used in All Grip Types.

o A too wide grip will often cause pain in an arthritic joint at the

base of the thumb

Maximum Grip Span for OA (Osteoarthritis) and RA (Rheumatoid

Arthritis) of moderate severity is not more than 2.5 to 3 inches.

Accommodation Examples - Continued:

Rheumatoid Arthritis – Joint Deformation

o Joint Deformation affects the types of grips

that can be made.

Example of Accommodation:

Instead of using a pinch grip, a person with

deformed finger joints may have to instead use

a lateral key pinch grip.

Lateral Key Pinch Grip

ie: Grip Used When Grasping and Turning a Key

Types of Hand Grasps There is no one standard classification of grasps.

Names for specific grasps can vary.

The following slides show examples of grasp

classifications.

Napier (1956)

Prehensile – Where an object is held by the hand

Power Grasp – Where an object is held in the palm of the hand

The forces of the thumb are opposed by the forces of the fingers

Muscular force is often high in the power grasp

Precision Grasp – Where an object is held between the

opposing fingers and thumb

Muscular force is usually more limited in the Precision grasp than in

the Power Grasp

Non-Prehensile – No seizing – The hand or finger applies pressure to an

object

The following Three Slides 10 hand grasps Classified by Karl Kroemer

(1986)

Coupling the Hand with the Handle

Prehensile Grasps

Ayoub, MacKenaie, Deivanayagam, Smith, Kroemer, Napier,

Ladsmeern

Hand Grasp / Power Grasp

Spherical Grasp – Spherical object in Hand

ie: Door Knob, Baseball

Cylindrical Grasp – Around circumference of a

cylindrical object

ie: Hammer Handle

Disc Grasp – Used on a disc shaped object

ie: Lid of Jar

Hook Grasp – Handle is hooked by digits 2 – 5

ie: Carrying a Briefcase

Pinch Grasps (Smith, 1985)

Pulp Pinch

Pad of thumb opposes pad of another finger

Pulp Pinch = Compression

Example: Pulp Pinch 2 = Thumb Opposes Index finger

For Small Contact Areas and High Precision

Example: Threading a Needle

Tip Pinch – Tip of thumb

opposes tip of another finger

Gripping Larger Contact Areas and

Applying Greater Force

Lateral Pinch (Key Pinch) – Thumb opposes the radial lateral aspect of the index finger in the clenched fist.

Lateral Pinches Aid Rotation

Chuck Pinch – similar to pulp and tip pinches except the thumb opposes both the index and middle finger simultaneously.

Pinch or Precision Grasps Tools that Require Precision Movements

Surgical Instruments, Pens or Pencils

Small Force

Grip that Facilitates Precise Motions

Fingers and Wrist Play a Prominent Role

Power Grasps Tools that Require More Muscular Force due to

Use

Weight

Size

Function

Need Larger Surfaces for the Hand to Contact to Form

More of a Power Grip

Ideas for a Better Grip Shape with Bulges and Indents for a better grip

Avoid Cylindrical Grips

Pinch Grips

Provide Contact Surface Area that is as large as the entire surface of the pad of the thumb or fingertips to increase strength

A Pinch Grip is Five Times More Stressful than a Power Grip (National Institute for Safety and Health)

Power Grips

Contact Surface Area large enough to allow contact with the entire palm of the hand

Better Grip Ideas continued: Eliminate Pressure Points - sharp edges and other

surface features that will cause local tissue pressures.

Padding can be added at Pressure Points of the palm

and fingers

Does the design work for left-handed people?

Size and Shape Gripping Area to Allow Alternatives

to the Standard Grip.

Texture or Non-Slip Material

can be added to surfaces to minimize slippage.

Inspirational Forms - Orbs

Orbs

Orb Cluster

3 Orbs – Large on End

3 Orbs – Large in Middle

Orbs with Box #1

Orbs with Box #2

Stone #1

Stone #2