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Matching Shoulder Job Demands To Functional Capacity
- 1. Shoulder Biomechanics:Using ergonomics & kinesiology to reduce occupationally related shoulder injuries
- 2. The Big Picture Job Demand Functional Capacity Match Demand & Capacity
- 3. Shoulder Function:Boney Anatomy Refresher Scapular spine Acromion Medial border Lateral border Suprasternal notch Coracoid process © Primal Pictures 2010 Inferior angle
- 4. Shoulder Function: Humeral and Scapular Motion
- 6. The perfect compromise between mobility and stability High Stability Low Stability Moderate Stability Low Mobility Moderate Mobility High Mobility
- 7. The perfect compromise between mobility and stability High Stability Low Stability Moderate Stability Low Mobility Moderate Mobility High Mobility
- 8. The Big Picture Demand On the Shoulder Shoulder Capacity Match Demand & Capacity
- 9. Are we currently doing a good job matching demands and capacities? 30% of claims are upper limb related $1850 - $10500 cost / claim
- 10. What if we don’t match demands and capacities? Tendon RC tendonitis Bicipital tendonitis RC tear Bursitis Nerve Suprascapular Thoracic outlet syndrome Muscle Prolonged muscle pain
- 11. What if we don’t match demands and capacities? Tendon RC tendonitis Bicipital tendonitis RC tear Bursitis Nerve Suprascapular Thoracic outlet syndrome Muscle Prolonged muscle pain
- 12. What if we don’t match demands and capacities? Tendon RC tendonitis Bicipital tendonitis RC tear Bursitis Nerve Suprascapular Thoracic outlet syndrome Muscle Prolonged muscle pain
- 13. What if we don’t match demands and capacities? Tendon RC tendonitis Bicipital tendonitis RC tear Bursitis Nerve Suprascapular Thoracic outlet syndrome Muscle Prolonged muscle pain
- 14. What if we don’t match demands and capacities? Tendon RC tendonitis Bicipital tendonitis RC tear Bursitis Nerve Suprascapular Thoracic outlet syndrome Muscle Prolonged muscle pain
- 15. Linking injuries to biomechanical mechanisms – Kinetics Impact Impact
- 16. Linking injuries to biomechanics to injury mechanisms – Kinematics Acromion Scapular rotation Humeral Head Impact Humeral head migration Impact © Primal Pictures 2010
- 17. Differentiating injury mechanics Role: To transfer large forces Role: To provide mobility Kinetics: Bone on Bone Compression & Shear Kinematics: Scapular and humeral positions and motions
- 19. Scapular
- 20. Humeral
- 21. Kinetics
- 22. Muscle force
- 25. Muscular controlRepetitive work Force direction
- 26. The Big Picture Ergonomics Force Posture Demand On the Shoulder Shoulder Capacity Repetition Duration Match Demand & Capacity
- 27. How can we reduce job demands for the shoulder? Critical Job Demands Time Arm elevation Reach distance Work direction Force Precision Repetition & Duration Posture Force & Posture Posture & Force Force Force & Duration
- 35. Arm elevation < 60°
- 36. Work is close to the body
- 37. Applied force is down
- 38. Low forces
- 40. > 10% of shift working overhead
- 41. Arm elevation > 60°
- 42. Extended reaches
- 43. Applied force is along the horizontal
- 44. High forces
- 45. High precision requirementsShoulder injury risk Shoulder injury risk A quick qualitative checklist to determine relative injury risk
- 46. The Big Picture Kinesiology Force ROM Posture Job Demand Functional Capacity Repetition Function Duration Match Demand & Capacity
- 47. Proper Posture Prevents Potential Problems! How can we increase work capacity of the shoulder?
- 49. Quick field tests for shoulder ROM Sorry the video links are not active through the academia.edu site.
- 50. Quick field tests for shoulder function Sorry the video links are not active through the academia.edu site.
- 51. Is the capacity adequate? Are corrective approaches required? ROM Function Integrating the test results
- 52. The Big Picture Force ROM Posture Job Demand Functional Capacity Repetition Function Duration Match Demand & Capacity
- 53. Applying your skillsScenario 1 8 years on the job 55 second work cycle 15 sec. above 60° – 10 sec. above 90° Precision placement required Good functional capacity
- 54. Modify the job demand
- 55. Scenario # 2 3 years on the job No set work cycle 20 minutes / shift working above 60° No precision required while overhead Poor functional capacity
- 56. Modify the functional capacity
- 57. Scenario # 3 14 years on the job 30 second work cycle 2 sec. above 60° Some precision requirement Good functional capacity PAIN on functional tests
- 58. Rotate away from the job
- 59. Scenario # 4 22 years on the job 15 min work cycle Arm height varies from 40 - 90° High cognitive workload Good functional capacity PAIN on functional tests
- 62. Scapular
- 63. Humeral
- 64. Kinetics
- 65. Muscle force
Editor's Notes
- NB population is 730,000 – if 0.2% of the population gets a shoulder injury, the total cost is just under 1 BILLION dollars!
- The most commonly injured tissues within the subacromial space include the supraspinatus tendon (rotator cuff tear), the long head of the biceps, and the subacromial bursa.
- Subacromial space contains supraspinatus tendon, long head of biceps tendon and bursa. This space is only about 7-13mm tall (Cotton & Rideout 1964; Golding 1962) and this size changes with posture, fatigue and injury. Currently the dominant theories suggest that the space is compromised through: A) Humeral head migration – where the humerus migrates superiorly in the glenoid, closing the subacromial space from the bottom up, which is thought to occur as a result of fatigued or injured rotator cuff muscles; or B) Abnormal scapular rotation – where the scapula rotates downwardly, protracts, and anteriorly tilts more than normal, compromising the subacromial space from the top down, which is thought to occur as a result of fatigue or injury to those muscles responsible for controlling scapular posture.
- The risk of developing a shoulder injury increases when the arms are elevated for more than 10% of the cycle or work shift.
- An arm height above 90° is most problematic and should be dealt with as soon as possible. An arm height above 60° is better, but not optimal as it is still linked with an increased risk. Arm height measured as an elevation of less than 60° is ideal (eliminating overhead work).
- Work location is measured as the linear distance between the shoulder joint center to the point of force application at the hand(s). Similar to traditional ergonomics approaches, shorter distances are more optimal than longer
- When possible, (re)design jobs that require forces to be exerted in a vertical direction, inline with gravity. This typically requires less muscle demand for the shoulder compared to tasks that require forces to be exerted in the horizontal direction.
- Force is always a critical job demand. Again, similar to traditional ergonomics approaches less force typically results in less shoulder muscle demand requirements.
- Precision is assessed qualitatively and through discussion with the worker. Jobs requiring precision typically require more shoulder demand than those not requiring precision. When possible, try to (re)design work such that precision is not required if the work must remain overhead.
- Overhead work is problematic and should be avoided whenever possible. However, when it can not be avoided, the risk of injury can at least be reduced (though not to zero) by addressing the factors noted on the left of the table. If you measure job demands that are more aptly described using the terms on the right side of the table then you may want to address those as soon as possible.
- Over time forward head postures can lead to shoulder impingement pain and muscle tears - especially when these poor postures are in combination with overhead working tasks.
- When measuring functional capacity you want to gather enough information to ask the following questions:Is the capacity adequate to meet the job demands?Are corrective approaches required to improve capacity, when capacity has been diminished or compromised?
- In this scenario the job demands are high, while the worker’s capacity is normal. Therefore the optimal approach to decrease injury risk might focus on decreasing the job demands.
- In this scenario the job demands are low, while the worker’s capacity is poor. Therefore the optimal approach to decrease injury risk might focus on improving the functional capacity of the worker to better meet the job demands.