The Farm Hand: Anatomy, Function, Trauma, and Injury Prevention

1. The Farm Hand:Anatomy, Function, Trauma, and Injury Prevention Carla Wilhite, OT Oklahoma State University-AgrAbility Specialist Millee Jorge, PT Langston University-Dean of Physical Therapy

2. Session Description The session will introduce participants to the structure of the hand, its functions, and to mechanisms and types of injuries in farm work environments. Participants will learn strategies for prevention of primary and secondary injury, and apply problem-solving skills to case examples

3. Objectives • Identify basic anatomy of the hand • Demonstrate understanding of hand function • List prevalent mechanisms of injury on farms • Injury prevention strategies

4. What is a hand? • A paired organ dominantly controlled by the opposing brain hemisphere • Our chief way for physically manipulating the environment • Richest source of tactile feedback (From the Wikipedia) Photo from: www.radiologyinfo.org

5. Anatomy • Structures • Shoulder • Upper arm • Forearm • Wrist • Hand • Fingers

6. Shoulder • Shoulder provides stability and dynamic movement to position hand for function • Main components • Scapula • Clavicle • Movement derives from: • Upper back • Rotator cuff Source: Netter’s

7. Upper arm and forearm • Bony structure • Humerus • Radius • Ulna • Movements derive from: • Flexors • Extensors • Supinators • Pronators Source: Netter’s Anatomy

8. Wrist • Carpal bones • Movements • Deviation • Flexion • Extension Source: www.assh.org

9. Hand • Metacarpals • Phalanges • Movements • Flex • Extend • Abduction • Adduction • Isolated movement vs. mass movement Source: www.radiologyinfo.org

10. Vascular Anatomy • Brachial artery • Radial artery • Ulnar artery • Palmar arch • Digital arteries • Anastamosis Source: Top: Netter’s anatomy, Bottom: www.assh.org

11. Neuroanatomy • Median Nerve • Ulnar Nerve Source: Netter’s anatomy

12. Neuroanatomy • Radial nerve Source: Netter’s anatomy

13. Connective tissues • Muscles • Move bony segments of the body • Tendons • Termination of a muscle into bone • Cartilage • Lines the articular joint surfaces • Ligaments • Connect across joints • Joint lubrication and bursa

14. Hand Functions • Grasping patterns • Hook, spheres, cylinders • Pinches • Key, tripod, inferior/superior • Fine motor manipulation • Sensation • Pain, touch, discrimination, object identification, vibration

15. Common hand injuries in farm work • Contributing factors • Farmer state of mind • i.e. attention, attitude toward safety • Musculoskeletal forces • i.e. wear and tear • Removal of safety shields or other protective equipment • Lack of training or skill Source: American Farm Bureau Photo Gallery

16. Mechanisms of farm hand injuries • Bites from farm animals • Wounds • Punctures • Canines • Crushing/tearing wounds • livestock • Risk of infection • Disease Source: www.assh.org

17. Mechanisms of farm hand injuries • Chemicals • Plants • Vaccines • Fertilizers • Herbicides • Pesticides • Wounds • Contact dermatitis • Lesions Source: www.dermnet.com

18. Mechanisms of farm hand injuries • Falls • Ladders • Stairs • Objects • Slippery hazards • Injuries • Colles (radial wrist) fracture • Scaphoid Non-union • Hand fractures Source:Copyright by Jonathan Cluett, 2001

19. Mechanisms of farm hand injuries • Machinery • Augers • Belts • Chains • Saws • Hitches • Hydraulic leaks • Mufflers/engines • Wounds • Amputations • Fractures • Avulsions • Crushing • Lacerations • Contusions • Burns

20. Mechanisms of farm hand injuries • Wounds • Tendon lacerations • Flexion • Extension http://www.davidlnelson.md/Tendon_Surgery.htm

21. Mechanisms of farm hand injuries • Musculoskeletal forces • Cumulative trauma • Repetitive use • Injuries • Sprains/strains • Tendonitis • Carpal tunnel • Bursitis • Cysts • Vascular compromise • Arthritis Source: http://orthoinfo.aaos.org

22. Mechanisms of farm hand injuries • Arthritis and Joint involvement • Pain • Joint enlargement • Joint erosion • Nodes • Deformities

23. Mechanisms of farm hand injuries • Vibration • Cold and heat • Vascular compromise • Nerve damage • Thermal injury • Raynaud’s syndrome (sympathetic) Source:http://www.assh.org

24. Mechanisms of farm hand injuries • Related injuries that affect hand function • Brachial plexus injury • Cubital tunnel • Rotator cuff trauma • Nerve injuries proximal to the hand • Mechanism • Pulling/pushing • Overuse • Dislocations • Lacerations/crushing Source: http:www.assh.org

25. Prevention of Hand Injuries • Design to fit body size • No such thing as “average size” • Provide adjustability in work station • Design to fit body posture • Three work positions: lying, sitting, and standing • But, transient postures of every kind between these postures (asymmetry): • Stooping, squatting, kneeling

26. Prevention of Hand Injuries • Designing for Hand Use • Hand tasks fall into five major groups • Fine manipulation (writing, assembling small parts) • Fast movements to an object (hitting a switch) • Frequent movements between targets (larger parts from bins to assembly) • Forceful activities with little displacement (turning a wrench) • Forceful activities with large displacements (hammering)

27. Prevention of Hand Injuries • Hand tools • Purpose of tool handle is to maintain secure control • Tool should fit contours of hands • Tool for right or left (or both) • Does tool require precision grip or power grip? • Consider energy between tool handle and hand, and tool to object • Manual tools or power? • See Therese Willkomm’s AgrAbility article!!!

28. Prevention of Hand Injuries by Agricultural Workers • Most effective control is to “engineer out” the risk of injury • When risk cannot be designed out: then use safety procedures and use of personal protective equipment Source: Nordin, Andersson, & Pope (1997)

29. Prevention of Hand Injuries by Agricultural Workers • Be familiar with personal protective equipment • Use correct gloves and safety equipment • Remove rings, watches, jewelry when working with power tools or on equipment • Do not wear gloves near machine gears or other devices • Replace gloves that are stretched, ragged, or torn • Keep machine guards in place • Use push sticks with table saws • When using sharp blades or needles keep point away from the body, cut away from the body, use retractable blades

30. Prevention of Hand Injuries by Agricultural Workers • Pay special attention to round or cylindrical parts that are unstable when placing them on a floor or bench. Use a roll stopper. • Use extra caution around “pinch points” • Check high pressure hoses for pinpoint leaks • Wash hands often to prevent spread of disease and infection • (Source: Maine Municipal Association Risk Management Services)

31. Prevention of Hand Injuries by Agricultural Workers • Take a break every hour or switch to another activity to prevent overuse of repetitive hand movements • Break tasks into short sessions • Store tools to prevent accidents • Choose the right tool for the job • Avoid sustained/constant gripping and awkward motions • Plan ahead, arrange work space • (Source: adapted from American Society of Hand Therapists, www.asht.org)

32. Prevention of Hand Injuries by Agricultural Workers • Upper extremity warm-up exercises • Fold your hands together, turn palms away from body, extend arms, hold 10 seconds and repeat 8 times (upper back and shoulder) • Then do it over head • Hold arm across chest, use opposite hand to push elbow gently toward chest, alternate with other arm (upper back and shoulder) • Extend arm, palm down, take opposite hand and bend wrist gently downward. Then do palm up, and stretch wrist back gently. • Gently open/close fists • “Play the piano” (Source: Adapted from ASHT)

33. Case studies