MSK 17 - Common Shoulder Disorders

Question 1

In which direction do 95% of shoulder dislocations occur and why?
What causes anterior + posterior dislocations?

Answer 1

• 90-95% anterior, as the joint is weak at its inferior aspect.
• Occurs when arm is abducted and externally rotated
• 2-4% occur posteriorly, due to violent muscle contraction, e.g.: seizure/trauma.

Question 2

What are the complications of shoulder dislocations?

Answer 2

1) Recurrence
2) Bankart’s lesion - part of glenoid labrum torn off
3) Hill Sach’s lesion - indentation fracture on posterolateral side of humeral head (head jams against lip of glenoid fossa)
4) Axillary nerve injury
5) Rotator cuff tears (increased risk with age)

Question 3

What is the most common type of clavicular fracture?
How do they occur?
What do they present with?

Answer 3

• 80% are mid-clavicular
• FOOSH or direct blow to clavicle (typically sport)
• pain/tenderness, assess for non-use of arm in infants

Question 4

What are the neurovascular structures at risk in a clavicular fracture?
Why does the shoulder drop after a clavicular fracture?

Answer 4

• Brachial plexus, subclavian artery + suprascular artery

- Sternocleidomastoid elevates medial segment, trapezius cant hold lateral segment, shoulder drops

Question 5

What is a rotator cuff tear?
How do they occur?
How would the patient present?

Answer 5

• 1 or more of the rotator cuff muscles (SITS) torn.
• Can be acute (traumatic) or chronic (age-related degeneration + chronic microtrauma)
• anterolateral shoulder pain, radiating down arm. Can’t lean on their elbow and weakness of shoulder abduction.(shoulder shrugs to compensate for loss of supraspinatus abduction).

Question 6

What is shoulder impingement syndrome?

Answer 6

• Irritation/inflammation of shoulder muscles as they pass through subachromical space. Caused by anything narrowing that space, e.g.: supraspinatus inflammation or osteophytes.
• Risks = repetitive lifting/overhead activities

Question 7

How does a patient with shoulder impingement present?

Answer 7

• Painful arc - between 60 and 120 degrees of shoulder abduction.
• Loss of strength, swelling, joint clicking

Question 8

What is adhesive capsulitis (frozen shoulder)?

What does it lead to?

Answer 8

• When the capsule becomes of the shoulder point become stiffened + inflamed.
• Leads to chronic pain + significant loss in ROM - usually worse at night

Question 9

What are the risk factors for adhesive capsulitis?

Answer 9

• Females>Males
• DM
• CV disease
• Thyroid disease
• Breast cancer

Question 10

What is the difference between primary and secondary shoulder OA?
In which joints does it occur?
What are the typical X-ray findings?

Answer 10

• Primarily = occurring on its town
• Secondary = after insult to joint, e.g.: after fracture
• Glenohumeral or acromiovclavicular
• think LOSS - Loss of joint space, Osteophytes, Subchondral sclerosis + Subchondral cysts