6
Shoulder and Humerus
General Knowledge
Anatomy
Acromion
| 1. | What are the four acromial centers of ossifcation? | 1. | Basiacromion Mesoacromion Metaacromion Preacromion |
| 2. | How can you remember the order from the base to the tip? | 2. | Alphabetical from base to tip |
| 3. | What is the most common location of an os acromiale? | 3. | At the junction of meso- and meta-acromion |
| 4. | If an os acromiale is present, how often is it bilateral? | 4. | 60% of the time |
| 5. | What is the indication for surgical treatment of os acromiale? How is it treated? What complication may develop despite treatment? | 5. | Only if symptomatic If small: excise If large: open reduction and internal fixation (ORIF) Risk of nonunion with ORIF |
| 6. | How is acromial morphology classified? | 6. | I: fat |
| II: curved | |||
| III: hooked | |||
| 7. | What radiographic study best visualizes acromial morphology? | 7. | Supraspinatus outlet view |
| 8. | What type is associated with best outcomes for nonoperative treatment of impingement? | 8. | I (flat) |
| 9. | What artery runs with the coracoacromial ligament? | 9. | Acromial branch of thoracoacromial artery |
| 10. | Where is the glenoid blood supply the poorest? | 10. | Anterosuperiorly |
Shoulder
| 11. | What are the borders of the quadrangular space? | 11. | Superior: teres minor Inferior: teres major Medial: triceps Lateral: surgical neck of the humerus |
| 12. | What are the two contents of the quadrangular space? | 12. | Posterior humeral circumflex artery Axillary nerve |
| 13. | What are the three borders of the triangular space? | 13. | Teres minor Teres major Long head of triceps |
| 14. | What are the contents of the triangular space? | 14. | Circumflex scapular vessels |
| 15. | What are the three borders of the triangular interval? | 15. | Long head of triceps Teres major Humerus |
| 16. | What are the two contents of the triangular interval? | 16. | Profunda brachii artery Radial nerve |
| 17. | Relative to the transverse scapular ligament, where does the suprascapular artery run? | 17. | Above the ligament |
| 18. | Relative to the transverse scapular ligament, where does the suprascapular nerve run? | 18. | Below the ligament |
| 19. | What is the innervation of the teres major? | 19. | Axillary nerve |
| 20. | What is the innervation of the supraspinatus? | 20. | Suprascapular nerve |
| 21. | What is the innervation of the deltoid? | 21. | Axillary nerve |
| 22. | What is the innervation of the subscapularis? | 22. | Upper and lower subscapular nerves |
| 23. | What is the innervation of the teres minor? | 23. | Lower subscapular nerve |
| 24. | Relative to the humeral intertubercular groove, what is the position of the pectoralis major? | 24. | Posterior |
| 25. | … of the latissimus dorsi? | 25. | Floor of groove |
| 26. | … of the teres major? | 26. | Anterior |
| 27. | What is the primary function of the latissimus dorsi? | 27. | Shoulder extension |
Capsular Ligaments
| 28. | What is the origin of the superior glenohumeral ligament (SGHL)? What is the insertion? | 28. | Origin: anterosuperior labrum Insertion: lesser tuberosity |
| 29. | In which arm position is the SGHL the primary restraint against external rotation and inferior translation? | 29. | Adducted |
| 30. | What is the origin of the coracohumeral ligament? What are the two sites of the insertion? What is its function? What does the coracohumeral ligament provide restraint against? | 30. | Origin: lateral base of coracoid process Insertions: greater and lesser tuberosities Reinforces the capsule of the rotator interval Inferior translation and external rotation in adduction (same as SGHL) |
| 31. | What is the origin of the middle glenohumeral ligament (MGHL)? What is the insertion? Where is the MGHL seen arthroscopically? | 31. | Origin: inferior to SGHL Insertion: lesser tuberosity Crosses subscapularis from superomedial to inferolateral |
| 32. | The MGHL is the primary static restraint against external rotation in what arm position? | 32. | 45 to 60 degrees of abduction |
| 33. | What is the origin of the inferior glenohumeral ligament complex (IGHLC)? What is the insertion? | 33. | Origin: inferior labrum Insertion: anatomic neck of humerus |
| 34. | What are the three components of the IGHLC? | 34. | Anterior band Posterior band Axillary pouch |
| 35. | The IGHLC is the primary anterior stabilizer of the shoulder in what arm position? | 35. | 90 degrees of abduction Also provides resistance against inferior translation in this position |
| 36. | What band of the IGHLC resists humeral translation in abduction and external rotation? | 36. | Anterior |
| 37. | What band resists humeral translation in abduction and internal rotation? | 37. | Posterior |
Humerus
| 38. | When plating the humerus, the radial nerve is a key consideration. What is the safe distance vertically from the lateral epicondyle? | 38. | 14 cm |
| 39. | … from the medial epicondyle? | 39. | 20 cm |
| 40. | … from trochlea to spiral groove? | 40. | 13 cm |
| 41. | … from trochlea to the site where radial nerve pierces intermuscular septum? | 41. | 7.5 cm |
Surgical Approaches: Key Points
Shoulder
| 42. | With shoulder arthroscopy, what is a common reason of interscalene block failure? | 42. | Inadequate anesthesia of T2 dermatome |
| 43. | What surgical site does this correspond to? | 43. | Posterior arthroscopy portal |
| 44. | An interscalene block administered at the time of surgery may also lead to palsy of what nerve? | 44. | Phrenic nerve |
| 45. | What is the lateral approach to the shoulder? | 45. | Deltoid splitting approach |
| 46. | How far distal to the acromion can the deltoid be safely split? Why? | 46. | No more than 5 cm With further split, axillary nerve at risk |
| 47. | What is the interval for the posterior shoulder approach? | 47. | Infraspinatus Teres minor |
| 48. | With the posterior approach, what should be avoided? Why? | 48. | Avoid dissecting below teres minor (within quadrangular space) Axillary nerve and posterior humeral circumflex arteries at risk |
| 49. | With the deltopectoral approach, which vein is at risk? | 49. | Cephalic |
| 50. | Excessive medial retraction for exposure may injure what structure? | 50. | Musculocutaneous nerve |
| 51. | What two structures should be protected at inferior edge of subscapularis? | 51. | Axillary nerve Anterior circumflex artery and veins |
Humerus
| 52. | For the anterolateral approach, what is the proximal interval? | 52. | Deltoid Pectoralis major |
| 53. | What is the distal interval? | 53. | Brachialis split |
| 54. | Why does the distal approach work? What nerves supply the brachialis? | 54. | Brachialis is duly innervated Musculocutaneous and radial nerves |
| 55. | For the posterior approach, what is the proximal interval? | 55. | Deltoid Triceps |
| 56. | How much of the humerus can be accessed proximally? | 56. | Up to 8 cm |
Distal Humerus
| 57. | For the anterolateral approach to the distal humerus, what is the interval? | 57. | Brachialis Brachioradialis |
| 58. | What structure is at risk? | 58. | Radial nerve |
| 59. | For the lateral approach to the distal humerus, what is the interval? | 59. | Brachioradialis Triceps |
| 60. | Then how does the deeper dissection proceed? | 60. | Lift extensor carpi radialis longus and brevis (ECRL and ECRB) off Work anterior to epicondyle and lateral collateral ligament (LCL) |
Key Pitching Concepts
| 61. | What are the five phases of throwing? | 61. | Windup Cocking Acceleration Deceleration Follow through |
| 62. | The highest shoulder rotatory torque, varus torque, compressive force, and shear force occur at what position? What phase does this correspond to? | 62. | Point of maximum shoulder external rotation Between cocking and acceleration phases |
| 63. | During the acceleration phase, what two things happen at the shoulder in terms of kinetics? | 63. | Increase in shear force Increase in flexion torque |
| 64. | The highest elbow compressive forces occur at what phase of throwing? | 64. | Deceleration |
| 65. | Maximum elbow valgus stress occurs at what phase? | 65. | Acceleration |
| 66. | What muscle has the greatest increase in electromyograph (EMG) activity during the early cocking phase? | 66. | Deltoid |
| 67. | What three muscles have the greatest increase in EMG activity during the late cocking phase? | 67. | Subscapularis Infraspinatus Teres minor |
| 68. | What four muscles have the greatest increase in EMG activity during the acceleration phase? | 68. | Pectoralis major Latissimus dorsi Serratus anterior Lower extremity musculature |
| 69. | What two muscles have the greatest increase in EMG activity during the follow through? | 69. | Rotator cuff Biceps |
| 70. | At the elbow, what function does the pronator serve during throwing? | 70. | Protects medial collateral ligament (MCL) from excessive valgus stress |
| 71. | With an insufficient MCL, what changes are seen in muscle activity during throwing: laterally versus medially? | 71. | Increased lateral activity Decreased medial activity |
Clinical Evaluation
Physical Examination: Special Tests
| 72. | O’Brien’s test is also called what? In which position is it performed? What is the key finding? What does it suggest? | 72. | Active compression test 10 degrees adduction, 90 degrees forward flexion, maximum pronation Pain with resistance that is decreased when the arm is supinated back to neutral is suggestive of superior labrum from anterior to posterior (SLAP) tear |
| 73. | How is Speed’s test performed? What can Speed’s test help diagnose? | 73. | Resisted forward flexion in scapular plane Pain suggests biceps pathology |
| 74. | How is the Yerguson test performed? What does a positive Yerguson test suggest? | 74. | Resisted supination Pain suggests biceps pathology |
| 75. | How is the drop arm test performed? The shoulder position is similar to what other test? What does a positive drop arm test suggest? | 75. | Maintain forward flexion in scapular plane Like Speed’s Inability = supraspinatus lesion |
| 76. | How can the lower and upper subscapularis be tested relatively independently? | 76. | Lower: lift off test Upper: belly press test |
Radiographic Evaluation
| 77. | What is a Zanca view used for? What view should also be obtained in conjunction? | 77. | Acromioclavicular (AC) joint pathology Axillary view too |
| 78. | What is a West Point view used for? | 78. | Bankart lesion |
| 79. | What is a Stryker view used for? What view should also be obtained in conjunction? | 79. | Hill-Sachs lesion Also anteroposterior (AP) internal rotation view |
Shoulder: Pathologic States
Shoulder Dislocation, Instability, and Management
Anterior Shoulder Dislocation
| 80. | If a manual reduction of an anterior shoulder dislocation is required, one should also evaluate for what associated injury? | 80. | Bankart lesion |
| 81. | What are the two components of the ideal position for shoulder immobilization after reduction? | 81. | Adduction External rotation |
| 82. | What is an important consideration when deciding duration of immobilization in an adult? | 82. | Shoulder stiffness |
| 83. | What is the most common complication associated with dislocation in a patient <20 years old? | 83. | Recurrence |
| 84. | What are the three most common complications in patients >40 years old? | 84. | 35% associated rotator cuff tear 10 to 15% recurrence 8% axillary nerve palsy |
| 85. |
