Joint mechanics   Lennard Funk
Joint mechanicsHundreds of articulations in the human bodyMany injuries occur to these joint structuresNo two joints are s...
Joint LubricationSynovial fluid  – Reduction of friction  – Distribution of force  – Nutrition for tissuesInjury implicatio...
Joint
Joint LubricationSynovial fluid produced by  SynoviocytesArthritis => damaged synoviocytes
Articular CartilageType II collagenDifferent fibres  orientation   – Shear forces   – tensile resistance     to swellingCre...
Articular Cartilage              lubricationSynovial joints   – Low coefficients of friction .     01-.04                 ...
Articular Cartilage:            AdaptationActive loading &  unloadingDegenerative changes  (OA)Aging   – ↓ water content  ...
Joint Mobility andMobility sometimes has very distinct endpoints  – Elbow or knee hyperextensionIn other cases variable so...
Joint Mobility andMobility sometimes has very distinct endpoints  – Elbow or knee hyperextensionIn other cases variable so...
Lever SystemsMost motion at the major joints results from the body’s structures acting as a system of levers  – Multiple “...
Levers
Levers• Levers are used to alter the resulting  direction of the applied force
Levers• Levers are used to alter the resulting  direction of the applied force• A lever is a rigid bar (bone) that turns  ...
Levers• Levers are used to alter the resulting  direction of the applied force• A lever is a rigid bar (bone) that turns  ...
Levers• Levers are used to alter the resulting  direction of the applied force• A lever is a rigid bar (bone) that turns  ...
Levers
LeversThe relationship of the points determines the type of lever
LeversThe relationship of the points determines the type of leverThe axis (joint), force (muscle insertion point), and the...
First ClassF                 R             A        F A R
First Class
First Class     A         R F
Neck extensionFirst Class     A         R F
Neck extensionFirst Class   Erector spinae                and Splenius     A         R F
First Class
First ClassF    A         R
First Class             Elbow extensionF    A         R
First Class             Elbow extension             TricepsF    A         R
First ClassF                         R    A                 A
First ClassDesigned for speed and range of motion when the axis is closer to the forceF                         R    A    ...
First ClassDesigned for speed and range of motion when the axis is closer to the forceDesigned for strength when the axis ...
Second Class       R           FA        A R F
Second Class
Second ClassR         F    A
Second Class                 Plantar flexionR         F    A
Second Class                 Plantar flexion                 Gastrocnemius                   and SoleusR         F    A
Second Class
Second ClassDesigned more for force
Third Class     F               RA         A F   R
Third Class
Third Class     F A          R
Elbow flexionThird Class     F A          R
Elbow flexionThird Class   Biceps brachii and                Brachialis     F A          R
Third Class
FUNCTIONAL   RELATIONSHIP     PRACTICAL         HUMANCLASS   ARRANGEMENT    ARM MOVEMENT       DESIGN        TO AXIS      ...
Factors In Use ofAnatomical Levers         F
Factors In Use of       Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA                F
Factors In Use of       Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA                F
Factors In Use of               Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA        ...
Balanced    Force Arm       Resistance Arm                                 RF                A
Balance with MoreForce Arm       Resistance Arm                                 RF            A
Balanced with Less    Force Arm   Resistance Arm                         RF                A
Factors In Use ofAnatomical Levers
Factors In Use of          Anatomical LeversA lever system can become unbalance when  enough torque is produced
Factors In Use of           Anatomical LeversA lever system can become unbalance when  enough torque is producedTorque is ...
Factors In Use of           Anatomical LeversA lever system can become unbalance when  enough torque is producedTorque is ...
Practical Application                        Resistance               Force
Practical ApplicationForce is produced by the  muscle                                    Resistance                       ...
Practical ApplicationForce is produced by the  muscleFA the distance from                                     Resistance  ...
Practical ApplicationForce is produced by the  muscleFA the distance from                                     Resistance  ...
Practical ApplicationForce is produced by the  muscleFA the distance from                                     Resistance  ...
Examples                   Resistance           Force
Examples1. How much torque needs  to be produced to move  45 kg when the RA is 0.25  m and the FA is 0.1                  ...
Examples1. How much torque needs  to be produced to move  45 kg when the RA is 0.25  m and the FA is 0.1                  ...
Examples1. How much torque needs  to be produced to move  45 kg when the RA is 0.25  m and the FA is 0.1                  ...
Example 1               RA = 0.25FA = 0.1           ?                           45A
Example 1F x 0.1 meters = 45 Kg x 0.25 meters                       RA = 0.25        FA = 0.1                   ?         ...
Example 1F x 0.1 meters = 45 Kg x 0.25 metersF x 0.1 kg = 11.25 Kg-meters                       RA = 0.25        FA = 0.1 ...
Example 1F x 0.1 meters = 45 Kg x 0.25 metersF x 0.1 kg = 11.25 Kg-metersF = 112.5 Kg                       RA = 0.25     ...
Example 2: Increasing the    FA                RA = 0.25FA = 0.15            ?                            45A
Example 2: Increasing the           FA2. What if the FA was increased to 0.15 meters?                           RA = 0.25 ...
Example 2: Increasing the           FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 meters...
Example 2: Increasing the           FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 meters...
Example 2: Increasing the           FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 meters...
Example 3: Decreasing the    RA               RA = 0.2FA = 0.1           ?                          45A
Example 3: Decreasing the            RA3. What if the RA was decreased to 0.2 meters?                           RA = 0.2  ...
Example 3: Decreasing the            RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 meters  ...
Example 3: Decreasing the            RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 metersF ...
Example 3: Decreasing the            RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 metersF ...
Summary
Summary• The actual torque needed to move a  given resistance depends on the  length of the FA and RA
Summary• The actual torque needed to move a  given resistance depends on the  length of the FA and RA• As the FA increases...
Summary• The actual torque needed to move a  given resistance depends on the  length of the FA and RA• As the FA increases...
Levers Continued
Levers ContinuedInside the body, several joints can be  “added” together to increase  leverage (e.g. shoulder, elbow, and ...
Levers ContinuedInside the body, several joints can be  “added” together to increase  leverage (e.g. shoulder, elbow, and ...
Lever Length               Z’      S’           S        Z
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’?         Z’                  S’                      ...
LeverLength
Lever        LengthA longer lever would increase speed at the end of the racquet unless the extra weight was too great. Th...
Wheels and Axles                   R = 3”                      R = 1”
Wheels and AxlesWheels and axles can enhance speed and                            R = 3” range of motion                  ...
Wheels and AxlesWheels and axles can enhance speed and                             R = 3” range of motionThey function as ...
Wheels and AxlesWheels and axles can enhance speed and                             R = 3” range of motionThey function as ...
Wheels and Axles               H
Wheels and AxlesConsider the humerus as an  axle and the forearm/hand  as the wheel                              H
Wheels and AxlesConsider the humerus as an  axle and the forearm/hand  as the wheelThe rotator cuff muscles  inward rotate...
Wheels and AxlesConsider the humerus as an  axle and the forearm/hand  as the wheelThe rotator cuff muscles  inward rotate...
Wheels and AxlesConsider the humerus as an  axle and the forearm/hand  as the wheelThe rotator cuff muscles  inward rotate...
Joints and          momentsNote, as a joint moves through its ROM, two things change:  – Instantaneous Center of Rotation ...
lenfunk@shoulderdoc.co.uk
Upcoming SlideShare
Loading in …5
×

Joint biomechanics

5,389
-1

Published on

0 Comments
7 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
5,389
On Slideshare
0
From Embeds
0
Number of Embeds
9
Actions
Shares
0
Downloads
276
Comments
0
Likes
7
Embeds 0
No embeds

No notes for slide
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • Synovial joint lubrication: in spite of the massive loads generated in them, synovial joints are efficient bearings with very low friction. The coefficient of friction of a synovial joint is around 0.02. This compares to 0.03 for ice sliding on ice. A coefficient of friction of 0.01 means that a load of 100 lb could be made to slide by applying a force of 1lb. Joint lubrication is the key to reduced friction. So, it is helpful to understand them in order to better understand and treat joint wear. It is still unclear how lubrication works, but there are many theories, based on man-made ball-bearings. What is clear is that no single mechanism is responsible and different modes of lubrication work at different stages of joint function. The joint is lined by wear resistant hyaline cartilage and is bathed by synovial fluid. Unlike a typical newtonian fluid synovial fluid has a viscosity that decreases with increasing shear rate. The function of a lubricant is to provide an intermediate layer with low shear resistance in between the two sliding surfaces to reduce friction. A thixotropic fluid would fit the bill perfectly.\nBasic lubrication is of two types: fluid-film, boundary and mixed.\nFluid film : a thin fluid film separates the bearing surfaces. Of two types: hydrodynamic and squeeze film. Hydrodynamic lubrication is unlikely to be feasible in vivo as the sliding velocity of joints are too low to generate a substantial fluid film. Squeeze film lubrication takes place by the production of a fluid film under pressure as the two bearing surfaces move perpendicularly towards each other. Fluid film and resultant load bearing capacity depends on fluid viscosity. It could explain lubrication under sudden loading but is not suitable for prolong loading conditions.\nBoundary: the bearing surfaces come to contact with each other, but "lubricin" from synovial fluid is attached to the cartilage surface and offers an interposed layer which when rubbed provides less resistance to shear.\nMixed: weeping lubrication: on load application synovial fluid is released or "wept" from articular cartilage. It separates the two bearing surfaces and reduces friction due to the hydrostatic pressure. On unloading the fluid is squeezed back in. This mechanism is not dependent on sliding speed .\n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • Joint biomechanics

    1. 1. Joint mechanics Lennard Funk
    2. 2. Joint mechanicsHundreds of articulations in the human bodyMany injuries occur to these joint structuresNo two joints are structurally identical
    3. 3. Joint LubricationSynovial fluid – Reduction of friction – Distribution of force – Nutrition for tissuesInjury implication: joint wear
    4. 4. Joint
    5. 5. Joint LubricationSynovial fluid produced by SynoviocytesArthritis => damaged synoviocytes
    6. 6. Articular CartilageType II collagenDifferent fibres orientation – Shear forces – tensile resistance to swellingCreep – constant load – compression loadCyclic loading – Benefits vs. damage
    7. 7. Articular Cartilage lubricationSynovial joints – Low coefficients of friction . 01-.04 moleculesTheories of lubrication – Boundary • "lubricin" from synovial fluid – Fluid film • hydrodynamic (non deformable) Fluid • Squeeze Film – right angle movement – short duration – Mixed
    8. 8. Articular Cartilage: AdaptationActive loading & unloadingDegenerative changes (OA)Aging – ↓ water content – ↓ PG – ↓ collagen content
    9. 9. Joint Mobility andMobility sometimes has very distinct endpoints – Elbow or knee hyperextensionIn other cases variable soft tissue properties and other factors limit ROMSome see stability as the joint’s ability to resist dislocation. Stability
    10. 10. Joint Mobility andMobility sometimes has very distinct endpoints – Elbow or knee hyperextensionIn other cases variable soft tissue properties and other factors limit ROMSome see stability as the joint’s ability to resist dislocation. Stability hi p! pt the e Exc
    11. 11. Lever SystemsMost motion at the major joints results from the body’s structures acting as a system of levers – Multiple “classes” of lever systemsFunctions: – Increase the effect of an applied force • Moment arms – Increase the effective velocity of movement • v=rω
    12. 12. Levers
    13. 13. Levers• Levers are used to alter the resulting direction of the applied force
    14. 14. Levers• Levers are used to alter the resulting direction of the applied force• A lever is a rigid bar (bone) that turns about an axis of rotation or fulcrum (joint)
    15. 15. Levers• Levers are used to alter the resulting direction of the applied force• A lever is a rigid bar (bone) that turns about an axis of rotation or fulcrum (joint)• The lever rotates about the axis as a result of a force (from muscle contraction)
    16. 16. Levers• Levers are used to alter the resulting direction of the applied force• A lever is a rigid bar (bone) that turns about an axis of rotation or fulcrum (joint)• The lever rotates about the axis as a result of a force (from muscle contraction)• The force acts against a resistance (weight, gravity, opponent, etc.)
    17. 17. Levers
    18. 18. LeversThe relationship of the points determines the type of lever
    19. 19. LeversThe relationship of the points determines the type of leverThe axis (joint), force (muscle insertion point), and the resistance (weight, etc.)
    20. 20. First ClassF R A F A R
    21. 21. First Class
    22. 22. First Class A R F
    23. 23. Neck extensionFirst Class A R F
    24. 24. Neck extensionFirst Class Erector spinae and Splenius A R F
    25. 25. First Class
    26. 26. First ClassF A R
    27. 27. First Class Elbow extensionF A R
    28. 28. First Class Elbow extension TricepsF A R
    29. 29. First ClassF R A A
    30. 30. First ClassDesigned for speed and range of motion when the axis is closer to the forceF R A A
    31. 31. First ClassDesigned for speed and range of motion when the axis is closer to the forceDesigned for strength when the axis is closer to the resistanceF R A A
    32. 32. Second Class R FA A R F
    33. 33. Second Class
    34. 34. Second ClassR F A
    35. 35. Second Class Plantar flexionR F A
    36. 36. Second Class Plantar flexion Gastrocnemius and SoleusR F A
    37. 37. Second Class
    38. 38. Second ClassDesigned more for force
    39. 39. Third Class F RA A F R
    40. 40. Third Class
    41. 41. Third Class F A R
    42. 42. Elbow flexionThird Class F A R
    43. 43. Elbow flexionThird Class Biceps brachii and Brachialis F A R
    44. 44. Third Class
    45. 45. FUNCTIONAL RELATIONSHIP PRACTICAL HUMANCLASS ARRANGEMENT ARM MOVEMENT DESIGN TO AXIS EXAMPLE EXAMPLE1ST F-A-R Resistance arm Balanced Axis near Seesaw Erector and force arm movements middle spinae neck in opposite extension direction Speed and Axis near Scissors Triceps range of force motion Force Axis near Crow bar (Strength) resistance2ND A-R-F Resistance arm Force Axis near Wheel Gatroc and and force arm (Strength) resistance barrow, soleus in same nutcracker direction3RD A-F-R Resistance arm Speed and Axis near Shoveling Biceps and force arm range of force dirt, catapult brachii in same motion direction
    46. 46. Factors In Use ofAnatomical Levers F
    47. 47. Factors In Use of Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA F
    48. 48. Factors In Use of Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA F
    49. 49. Factors In Use of Anatomical LeversA lever system can be balanced if the F and FA equal the R and RA F(A = Arm - distance from A)
    50. 50. Balanced Force Arm Resistance Arm RF A
    51. 51. Balance with MoreForce Arm Resistance Arm RF A
    52. 52. Balanced with Less Force Arm Resistance Arm RF A
    53. 53. Factors In Use ofAnatomical Levers
    54. 54. Factors In Use of Anatomical LeversA lever system can become unbalance when enough torque is produced
    55. 55. Factors In Use of Anatomical LeversA lever system can become unbalance when enough torque is producedTorque is the turning effect of a force; inside the body it caused rotation around a joint.
    56. 56. Factors In Use of Anatomical LeversA lever system can become unbalance when enough torque is producedTorque is the turning effect of a force; inside the body it caused rotation around a joint.Torque = Force (from the muscle) x Force Arm (distance from muscle insertion from the joint)
    57. 57. Practical Application Resistance Force
    58. 58. Practical ApplicationForce is produced by the muscle Resistance Force
    59. 59. Practical ApplicationForce is produced by the muscleFA the distance from Resistance Force joint (i.e. axis or folcrum) to insertion of the force
    60. 60. Practical ApplicationForce is produced by the muscleFA the distance from Resistance Force joint (i.e. axis or folcrum) to insertion of the forceResistance could be a weight, gravity, etc.
    61. 61. Practical ApplicationForce is produced by the muscleFA the distance from Resistance Force joint (i.e. axis or folcrum) to insertion of the forceResistance could be a weight, gravity, etc.RA the distance from joint to the center of the resistance
    62. 62. Examples Resistance Force
    63. 63. Examples1. How much torque needs to be produced to move 45 kg when the RA is 0.25 m and the FA is 0.1 Resistance Force meters?
    64. 64. Examples1. How much torque needs to be produced to move 45 kg when the RA is 0.25 m and the FA is 0.1 Resistance Force meters?Use the formula F x FA = R x RA
    65. 65. Examples1. How much torque needs to be produced to move 45 kg when the RA is 0.25 m and the FA is 0.1 Resistance Force meters?Use the formula F x FA = R x RANote: A Newton is the unit of force required to accelerate a mass of one kilogram one meter per second per second.
    66. 66. Example 1 RA = 0.25FA = 0.1 ? 45A
    67. 67. Example 1F x 0.1 meters = 45 Kg x 0.25 meters RA = 0.25 FA = 0.1 ? 45 A
    68. 68. Example 1F x 0.1 meters = 45 Kg x 0.25 metersF x 0.1 kg = 11.25 Kg-meters RA = 0.25 FA = 0.1 ? 45 A
    69. 69. Example 1F x 0.1 meters = 45 Kg x 0.25 metersF x 0.1 kg = 11.25 Kg-metersF = 112.5 Kg RA = 0.25 FA = 0.1 ? 45 A
    70. 70. Example 2: Increasing the FA RA = 0.25FA = 0.15 ? 45A
    71. 71. Example 2: Increasing the FA2. What if the FA was increased to 0.15 meters? RA = 0.25 FA = 0.15 ? 45 A
    72. 72. Example 2: Increasing the FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 meters RA = 0.25 FA = 0.15 ? 45 A
    73. 73. Example 2: Increasing the FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 metersF x 0.15 = 11.25 Kg-meters RA = 0.25 FA = 0.15 ? 45 A
    74. 74. Example 2: Increasing the FA2. What if the FA was increased to 0.15 meters?F x 0.15 meters = 45 Kg x 0.25 metersF x 0.15 = 11.25 Kg-metersF = 75 Kg RA = 0.25 FA = 0.15 ? 45 A
    75. 75. Example 3: Decreasing the RA RA = 0.2FA = 0.1 ? 45A
    76. 76. Example 3: Decreasing the RA3. What if the RA was decreased to 0.2 meters? RA = 0.2 FA = 0.1 ? 45 A
    77. 77. Example 3: Decreasing the RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 meters RA = 0.2 FA = 0.1 ? 45 A
    78. 78. Example 3: Decreasing the RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 metersF x 0.1 = 9 Kg-meters RA = 0.2 FA = 0.1 ? 45 A
    79. 79. Example 3: Decreasing the RA3. What if the RA was decreased to 0.2 meters?F x 0.1 meters = 45 Kg x 0.2 metersF x 0.1 = 9 Kg-metersF = 90 Kg RA = 0.2 FA = 0.1 ? 45 A
    80. 80. Summary
    81. 81. Summary• The actual torque needed to move a given resistance depends on the length of the FA and RA
    82. 82. Summary• The actual torque needed to move a given resistance depends on the length of the FA and RA• As the FA increases or RA decreases, the required torque decreases.
    83. 83. Summary• The actual torque needed to move a given resistance depends on the length of the FA and RA• As the FA increases or RA decreases, the required torque decreases.• As the FA decreases or RA increases, the required torque
    84. 84. Levers Continued
    85. 85. Levers ContinuedInside the body, several joints can be “added” together to increase leverage (e.g. shoulder, elbow, and wrist.
    86. 86. Levers ContinuedInside the body, several joints can be “added” together to increase leverage (e.g. shoulder, elbow, and wrist.An increase in leverage can increase velocity
    87. 87. Lever Length Z’ S’ S Z
    88. 88. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    89. 89. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    90. 90. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    91. 91. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    92. 92. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    93. 93. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S Z
    94. 94. Lever LengthWhere is the velocity or speed the greatest; at S’ or Z’? Z’ S’ S ZHow can this principle be applied to tennis?
    95. 95. LeverLength
    96. 96. Lever LengthA longer lever would increase speed at the end of the racquet unless the extra weight was too great. Then the speed may actually be slower.
    97. 97. Wheels and Axles R = 3” R = 1”
    98. 98. Wheels and AxlesWheels and axles can enhance speed and R = 3” range of motion R = 1”
    99. 99. Wheels and AxlesWheels and axles can enhance speed and R = 3” range of motionThey function as a form of lever R = 1”
    100. 100. Wheels and AxlesWheels and axles can enhance speed and R = 3” range of motionThey function as a form of leverMechanical advantage = radius of wheel / radius of axle R = 1”
    101. 101. Wheels and Axles H
    102. 102. Wheels and AxlesConsider the humerus as an axle and the forearm/hand as the wheel H
    103. 103. Wheels and AxlesConsider the humerus as an axle and the forearm/hand as the wheelThe rotator cuff muscles inward rotate the humerus a small amount H
    104. 104. Wheels and AxlesConsider the humerus as an axle and the forearm/hand as the wheelThe rotator cuff muscles inward rotate the humerus a small amountThe hand will travel a large amount H
    105. 105. Wheels and AxlesConsider the humerus as an axle and the forearm/hand as the wheelThe rotator cuff muscles inward rotate the humerus a small amountThe hand will travel a large amountA little effort to rotate the humerus, results in a significant amount of movement at the hand H
    106. 106. Joints and momentsNote, as a joint moves through its ROM, two things change: – Instantaneous Center of Rotation • Rotation • Sliding • Rolling – Muscle Line of ActionThese combine to change the moment arm
    107. 107. lenfunk@shoulderdoc.co.uk
    1. Gostou de algum slide específico?

      Recortar slides é uma maneira fácil de colecionar informações para acessar mais tarde.

    ×