Lecture 4

Question 1

What is the medial epicondyle?

Answer 1

Medial projection on humerus

3rd ossification center to appear but last to fuse

Question 2

What are the stages of medial epicondyle fracture and their progression to become intra articular?

Answer 2

Stage 1 = fragment is free

Stage 2. = free fragment starts to head towards articular surface

Stage 3= fragment in articular surface between trochlea and ulna. 16% of medial epicondyle fractures, 16% of injuries can cause ulnar nerve damage

Question 3

Explain what’re lateral epicondyle fractures?

Answer 3

Uncommon compared to medial
Avulsion caused by valgus force

Due to contraction of common extensor tendons in children and a direct blow in adults

Lateral epicondylitis - tennis elbow (throwing sports)

Epicondyle and condyle are different structures, and fractures of lateral condyle is more common than of the lateral epicondyley

Question 4

What relevance do fat pads have with epicondyle fractures?

Answer 4

Fat pads appear when injury/disruptions are INTER articular

So epicondyle fractures cause no fat pads

But condylar fractures do

BUT EPICONDYLE FRACTURES can become inter articular

Question 5

Explain what’re lateral condyle fractures

Answer 5

2nd most common elbow fracture in child with supracondylar being 1st

Rare in adults

FOOSH with head of radius striking capitulum or avulsion of extensor carpi radialis longus and brevis due to Varus stress on supinated forearm

Age 6 = poor outcome if treatment done early

Question 6

How are lateral condyle fractures classified?

Answer 6

Milch 1 = vertical fracture through capitellum ossification (rare)

Milch 2 = fracture runs medial to capitellum ossification (common)

Question 7

What’re olecranon fractures?

Answer 7

Seen in young adults due to high energy trauma

• fall on elbow or high energy blow to posterior portion of elbow (car window with arm resting)
• FOOSH with extended elbow
• avulsion of contracted triceps
• stress fracture from repetitive forceful elbow extensions (ie. gymnastics, weight lifting)

Can involve ulnar nerve (as it runs along medial aspect of olecranon) but uncommon

Contraction of triceps, can seperate proximal fragment and ORIF done

Question 8

Explain what’re coronoid fractures

Answer 8

Uncommon, due to avulsion of brachialis tendon, or stearing force from trochlea

Leads to joint instability as coronoid is key for elbow stability

Swelling, pain in elbow joint, limited ROM

Question 9

What is the coronoid process?

Answer 9

Acts like an anterior buttress for elbow, as it engages with the trochlea and stops posterior displacement of humerus

Question 10

Explain the classifications of corocoid fracture

Answer 10

Type 1 - associated with “terrible triad” injury, posterior or posteolateral dislocation of humerus, radial head fracture, and coronoid fracture. Avulsion of tip of coronoid, treatment not required

Type 2 - fracture involved 50% or less of the height of coronoid, treatment not required

Type 3 - more than 50% fracture, usually due to posterior or anterior fracture dislocation of olecranon. Here, the olecranon can move anterior and posterior as there is no support

Question 11

What makes a terrible triad?

Answer 11

Anterior dislocated elbow joint

Fractured head of radius

Coronoid process fracture - type 1

Question 12

Explain what are capitellum fractures?

Answer 12

FOOSH with semi-flexed elbow. So pt. Will have limited flexsion of elbow as displaced capitellum stops flexsion

Rare (<1% of elbow fractures), commonly associated with children >10 yo

Females tend to get this because greater carrying angle

20% capitellum fracture cases have radial head fractures

Question 13

Is it hard to distinguish a fracture of the capitellum?

Answer 13

Can be missed on inocorrectly positioned elbow series

Lateral projection of elbow usually shows double arc, thus mimicking the double arc of a capitellum and trochlea

Torchlea fracture results on degree of flexsion of elbow during fall

AP shows double curvature of capitellum

CT is needed to see if trochlea is fractured

Question 14

What’s a capitellum microtrauma?

Answer 14

Repetitive valgus stress

Lateral compartment compression force on capitellum causing microtrauma to capitellum

Leads to avascular necrosis of capitellar epiphysis, or osteochondrtis of capitellum

Osteochondritis dissecans of capitellum (panner’s disease) - lack of blood supply to capitellum and it starts to degrade into fragments

Common in base ball, and gymnastics

Question 15

Why’s the shoulder so prone to injury?

Answer 15

It’s a lax joint, which allows for great mobility in many directions and has many ligaments….so is very vulnerable to injury

Question 16

What provides the shoulder with dynamic stability and great ROM?

Answer 16

Muscles and tendons of rotator cuff ie. supraspinatus, infraspinatus, teres minor, and subscapularis

Question 17

How does the shoulder experience both static and dynamic stability?

Answer 17

Static = from capsular ligaments, the articular components (glenoid) and glenoid labrum of glenohumeral joint. All non-contractile tissue and are the base of support for shoulder joint.

Dynamic= provided by contractile tissues like muscles around shoulder ie. rotator cuff muscles and tendons). Supraspinatus muscles contributes most and biceps, pectoralis maj, latissimus dorsi, traps, deltoid have important functional roles.

Question 18

What’s the function of the glenoid labrum?

Answer 18

Fibrous ring of cartilage

Increase depth of glenoid fossa as well as serving as an anchorage point for ligaments

Question 19

What’s SLAP tear?

Answer 19

Superior labrum anterior and posterior (SLAP)

Tear of labrum at anterior and posterior region of biceps brachii muscle insertion… so tear at the superior labrum d

Can be due to the tendon being involved in injury

Question 20

How does rotation effect the humeral head’s appearance?

Answer 20

External rotation = greater tuberosity shown. Detect glenohumeral arthritis, coracoid process fracture, glenoid fracture, proximal humerus fracture, compression fracture of humeral head

Neutral rotation = detects glenohumeral arthritis, coracoid process fracture, glenoid fracture, proximal humerus fracture, posterior glenohumeral instability
Evaluates: humeral head position relative to glenoid
AC joint position/arthritis
Rotator cuff calcifications
Acromial spurring

Internal rotation = detects hill-Sachs lesions, glenohumeral arthritis, corocaid lrocess fracture, glenoid fracture, proximal humerus fracture

Question 21

List the shoulder and proximal humerus injuries in children and their regions

Answer 21

Proximal metaphysis humerus 
Shaft (diaphysis) humerus 
Proximal epiphysis humerus 
Shoulder dislocation 
Scapula, AC joint, SC joint 
Clavicle

Question 22

Explain injuries that occur at proximal metaphysis of humerus

Answer 22

5-12 years old
5cm ish distal to surgical neck

Usually torus and greenstick fractures

If <5 years probs non-accidental injury

Question 23

Explain injuries of shaft (diaphysis) of humerus

Answer 23

> 10 yo, uncommon

Usually transverse or spiral fracture, sometimes greenstick

<3 yo NAI especially if spiral

Question 24

Exaplin the injuries relevant to the proximal epiphysis of humerus

Answer 24

Uncommon, usually in teens with 75% cases being type 3 salter Harris

If <5 yo, type 1 of salter Harris

Question 25

Explain injuries such as a shoulder dislocation

Answer 25

Rare Occurs when fusion epiphysis occurs

Question 26

Explain injuries relevant to scapula, AC joint, SC joint

Answer 26

Rare Non accidental, especially if scapula fracture

Question 27

Explain injuries relevant ti the clavicle

Answer 27

Common Usually at middle 3rd 50% cases are greenstick

Question 28

What are the Causes of labrum tears?

Answer 28

Acute trauma or repetitive overhead shoulder motion eg. Tennis, weightlifting, gymnastics, etc Tears due to ageing (>40yo) but are different type of tear SLAP due to MVA, FOOSH, FORCEFul traction arm (catching heavy object), shoulder dislocation, rapid or forceful movement of arm when raised above shoulder

Question 29

What’re the functions and attachment points of the rotator cuff muscles?

Answer 29

Supraspinatus attaches to superior facet of grater tuberosity and ABDUCTS HUMERUS Infraspinatus attaches to posterior facet of greater tuberosity and EXTERNALLY ROTATES HUMERUS Teres minor attaches to inferior facet of greater tuberosity and EXTERNALLY ROTATES HUMERUS Subscapularis attaches to lateral tuberosity and INTERNlly ROTATES HUNERUS

Question 30

What is shoulder impingement (painful arc syndrome)

Answer 30

Occurs on rested abduction between 60 deg and 120 deg, when inflamed tendon presses against the acromion. On abduction, supraspinatus tendon glides underneath acromion with subacromial bursa inbetween (SA space) Coracoacromial ligaments prevent anterior movement of supraspinatus tendon and the space in supraspinatus outlet is restrictive and so the tendon can be compressed cause of acromion shape and so impinge into outlet Painful arc syndrome can also occur due to clacific deposit in supraspinatus tendon Caused by subacromial dysfunction Outside the range of 60-120 deg is painless Should do Lateral projection to see better

Question 31

Explain what’s an anterior glenohumeral dislocation

Answer 31

Most common (>95%) and in young men Pt. <20yo, 90% will have recurrent dislocation Due to forced external rotation of abducted arm, FOOSH, direct blow to shoulder in post-ant direction Presentation= abducted arm 10-20 deg and externally rotated, deltoid + acromion prominence now post-lat, head is felt ant. To joint (sucoracoid space)

Question 32

Why is an anterior glenohumeral dislocation so common?

Answer 32

Because the posterior musculature is greater, therefore the glenohumeral joint is more protected, but anterior musculature and ligaments less robust and lead to anterior dislocation

Question 33

What’re the complications of glenohumeral dislocations?

Answer 33

Bony Bankart lesions, from avulsion of anterior-inferior glenohumeral ligament resulting in avulsion of inferior rim of glenoid fossa Hill Sachs lesion (posterolateral oortion of humeral head) due to impaction on inferior margin of glenoid fossa...so compression fracture of posterior-superior aspect of head humerus as it strikes inf-post rim of glenoid fossa (results in hill Sachs lesion’...recurrent dislocation from now Avulsion of greater tuberosity (supraspinatus tendon) Inferior glenoid rim can fracture, and if > 20% is fractured, thus will cause recurrent dislocations

Question 34

What location configurations can the humeral head be found in when anteriorly dislocated?

Answer 34

Sub coracoid anterior dislocation with greater tuberosity avulsion Anterior dislocation with compression fracture (hill Sachs) Sub coracoid anterior dislocation

Question 35

Explain a posterior dislocation of the humerus

Answer 35

Uncommon, easily missed 2-5% of shoulder dislocations Due to FOOSH arm internally rotated (50% cases), glenoid retroversion or hyperplasia of glenoid fossa Can be Associated with seizure (epileptic or electrocution)

Question 36

What are the complications of a posterior dislocation of the shoulder? Unable to externally rotate shoulder

Answer 36

Reverse hill Sachs lesion (in antero-medial aspect of humeral head) Posterior Bankart lesion Easily misdiagnosed and untreated so recurrent dislocations Glenoid rim fracture or lateral tear Lesser tuberosity avulsed

Question 37

What the different appearances of a posterior glenohumeral dislocation?

Answer 37

Lightbulb sign = axis of head and shaft same Internal roatation appearance of humeral head = Rim sign = widening glenohumeral space >6mm Vacant anterior glenoid sign = Trough sign = vertical line made by compression fracture on anterior portion of humeral head(reverse hill Sachs) Overlap sign = loss of half moon overlap (medial humeral head overlapping glenoid rim )

Question 38

Exaplin the mechanisms of a inferior shoulder dislocation

Answer 38

Rare, <2% FOSH that’s hyperabducted. Humerus pivots against acromion and dislocated inferiorly and medial to acromion

Question 39

What are the possible compilations of the inferior shoulder dislocation

Answer 39

High complication rate (like 80%) Avulsion of greater tuberosity Approx 60% wither vascular or nervous damage (transient or permenant) Rotator cuff and labrum tears can occur Can get bilateral luxatio erecta (extremely rare)

Question 40

Explain what a shoulder subluxation is and how it comes about

Answer 40

Partial dislocation, that’s due to muscular laxity of the shoulder Commonly on stroke pts who have a painful hemillegic shoulder (muscle weakness or partial paralysis) Occur in 17-66% of pts with post-hemiplegia

Question 41

Explain the causes of subluxations of the shoulder

Answer 41

Yes, a pseudodislocation can be mistaken for a shoulder dislocation AP demonstrates an inferior displaced humeral head but on lagerL or axial there will be no anterior or posterior displacement relative to glenoid fossa Displacement of humeral can be due to haemarthrosis (bleeding into joint cavity), occult fracture or due to pathology which generates a large joint effusion Can also occur due to septic arthritis (effusion of glenohumeral joint)

Question 42

Explain acromio-clavicular joint injurieies and their classification system

Answer 42

Causes ; bike crash, tackles in sport Type 1-3 injuries get conservative treatment - 1:strain - 2: acromioclavicular ligament torn and separation - 3: AC lib and CoracoClavicular lig (rupture) and large separation (normally width 1-3mm in young, <1mm in older) Type 4-6 injuries get surgical treatment - 4: Anterior dislocation of shoulder and subluxation of acromioclavicular joint are very similar in how they look

Question 43

Explain the classifications of clavicle fractures

Answer 43

Type 1: most common (>70%) right in middle shaft, and then there’d comminuted Type 2: may involve coracoclavicular ligs ie. fracture near the acromial end of clavicle Type 3: medial 3rd, uncommon fracture (<5%))

Question 44

What’s clavicle osteolysis?

Answer 44

Osteolysis is an active resorption of bone matrix by osteoclasts (literally the reverse of ossification) - lacking in clavicle So clavicle osteolysis can be due to cleidocranial dysplasia (that thing Dustin from ST has)

Question 45

Explain the complications of a Sternoclavicular joint dislocation

Answer 45

``` Posterior dislocation (rare) leads to vascular compression Right side = compression of brachiocephalic artery Left side = compression of left brachiocephalic vein, or pneumothorax ``` Anterior dislocation (75% common)

Question 46

Explain what a Sternoclavicular joint dislocation is

Answer 46

Dislocation requires considerable force via direct or indirect blow to shoulder, MVA, sports or fall - posterior blow = anterior dislocation - anterior blow, and blow over medial end of clavicle = post dislocation You would do a CXR, AP both clavicles, axial both clavicles (30-40 deg Cephalic angulation) and CT