Repetitive Motion Injury and Hand tools design

Question 1

What are the 4 main causes of Cumulative Trauma Disorder?

Answer 1

• excessive force
• awkward or extreme joint motions
• high repetition
• duration of work

Question 2

What is Cubital Tunnel Syndrome? What causes it, what are the symptoms? It’s popular/common name?

Answer 2

• compression of Ulnar nerve in elbow
• tinging and numbness
• believed to be caused by resting elbow on hard surface or sharp edge
• known as clothes wringing disease

Question 3

What is Tendonitis? What causes it, what are the symptoms? Its other name?

Answer 3

• Inflammation of a tendon
• symptoms are pain, burning, swelling
• Slot machine tendinitis

Question 4

What is “Trigger finger”, what are the symptoms

Answer 4

Thoracic outlet syndrome

• results from compression of 3 nerves of arm and blood vessels
• arm becomes numb and difficult to move

Question 5

What are 5 inappropriate work methods that can lead to CTD

Answer 5

• repetitive hand movements with high force
• flexion and extension of hand
• high force pinch grip
• new job
• back from vacation
• uncomfortable work postures
• lack of experience

Question 6

What are the 5 guidelines for hand posture that can help reduce CTD?

Answer 6

• watch out for sudden flexion or extension of the hand or fingers
• avoid extreme ulnar deviation and radial deviation
• avoid operations that require more than 90 wrist rotation
• keep forces low during rotation or flexion of the writst
• for operations that require finger pinches keep the forces below 10 N

Question 7

What are the 4 guidelines for product design that can help reduce CTD

Answer 7

• minimize the number of screws and fasteners used in the assembly- minimize the torque required for sizes
• locate fasteners and screws at “natural” angles so they are easy for the operator to insert
• design a product with large parts to permit gripping with fingers and palm instead of pinching