Biomechanics Of Rotator Cuff Tears

Question 1

What is the term used to describe when two or more muscles acting in different directions influence the rotation of a joint in a specific region?

Answer 1

Force coupling

Question 2

What two planes does force coupling occur in?

Answer 2

Coronal and transverse planes

Question 3

Describe the mechanism of the coronal force couple?

Answer 3

The coronal force couple occur from contraction of the deltoid and supraspinatus muscles . This compresses the humerus into the glenoid Fossa during abduction

Question 4

Describe the mechanism of force coupling in the travers plane?

Answer 4

The Subscapularis and infraspinatus muscles play a synergistic role in concavity compression.

Question 5

What muscles of the rotator cuff play the largest role in force coupling?

Answer 5

Subscapularis and infeaspinatus play the largest role

Question 6

What percentage of rotator cuff strength comes from the Subscapularis?

Answer 6

53%

Question 7

What percentage of rotator cuff strength comes from the Infraspinatus?

Answer 7

22%

Question 8

What percentage of rotator cuff strength comes from the supraspinatus?

Answer 8

14%

Question 9

What percentage of rotator cuff strength comes from the Teres minor?

Answer 9

10%

Question 10

What rotator cuff muscles is responsible for the most strength and stability of the rotator cuff?

Answer 10

Subscapularis at 53%

While all the other 3 which are responsible for 47%

Question 11

What does passive range of motion mean?

Answer 11

Passive range of motion can be defined as what is achieved when an outside force, such as a therapist, causes movement of a joint.

Question 12

What does active range of motion mean?

Answer 12

Active range of motion is what can be achieved when opposing muscles contract and relax, resulting in joint movement.

Question 13

What are the results from a massive tear of a posterior superior rotator cuff tear?

Answer 13

Results in super physiological passive internal rotation.

Question 14

What are the results from a massive tear of a anterior superior rotator cuff tear?

Answer 14

Decrease passive external rotation and increased movement in passive internal rotation

Question 15

Loss of integrity of the anterior superior rotator cuff lead to weakness in _____________?

Answer 15

Active internal rotation and increased movement in active external rotation

Question 16

What is tear propogation

Answer 16

The spreading of a tear as a result from imbalanced force coupling .

Question 17

What is pseudoparalysis?

Answer 17

Inability to perform more that 90deg of active forward elevation with fully intact passive range of motion in the absence of neurological impairment

Question 18

Patients are at a higher risk of pseudoparalysis if which structures are completely disrupted?

Answer 18

The subscapularis or all three posterior superior muscles

Question 19

What nerve is impinged when you have a large posterior superior tear?

Answer 19

Suprascapular nerve , which leads to degeneration supraspinatus and Infraspinatus

Question 20

What are extrinsic factors that cause rotator cuff tear?

Answer 20

Impingement and demographic

Question 21

What are intrinsic factors that cause rotator cuff tear?

Answer 21

Age related degeneration, hypovascualrity, inflammation and oxidative stress

Question 22

What is the majority cause of rotator cuff tears? Gradual onset or acute injury?

Answer 22

Gradual onset

Question 23

Is surgical intervention typically required for partial or incomplete tears?

Answer 23

No

Question 24

What are the characteristics of a rotator cuff tear?

Answer 24

Size, depth, retraction,acromiohumeral interval, goutallier classification and contaminant pathology

Question 25

What is the goutallier classification ?

Answer 25

See photo

Question 26

Tears generally affecting less that <50% typically treated with good results of

Answer 26

Debriefing without/with acromioplasty

Question 27

When tear depth is great than >50%

Answer 27

Surgical intervention focusing on repair is successful