MSK Revision 5

Question 1

Describe the three types of hip dislocation [2]

Which is most common? [1]

Answer 1

Posterior dislocation:
- Accounts for 90% of hip dislocations.
- The affected leg is shortened, adducted, and internally rotated.

Anterior dislocation:
- The affected leg is usually abducted and externally rotated. No leg shortening.

Central dislocation

Question 2

Hip dislocations can be classified into two primary categories: [cause]

Answer 2

Hip dislocations can be classified into two primary categories: traumatic and atraumatic.

Question 3

Describe the subtypes of anterior dislocations with regards to the patient presentation and palpation findings:
- Obturator dislocation [2]
- Pubic dislocation [2]

Answer 3

Obturator dislocation:
- Patient presentation: Clinically hip appears in extension and external rotation
- Palpation findings: Prominence of the greater trochanter laterally; femoral head palpable in the medial thigh region near the obturator foramen.

Pubic dislocation:
* Patient presentation: Clinically hip appears in flexion, abduction, and external rotation
* Palpation findings: Femoral head palpable in the inguinal region; lesser trochanter prominence may be appreciated posteriorly.

Question 4

Describe the subtypes of posterior dislocations with regards to the patient presentation and palpation findings:
- Iliac dislocation [2]
- Ischiatic dislocation [2]

Answer 4

Subtype: Iliac
* Patient presentation: Affected limb is adducted, internally rotated, and mildly flexed at the hip joint.
* Palpation findings: Prominence of the greater trochanter posteriorly; femoral head palpable in the buttock region near the sciatic notch.

Subtype: Ischiatic
* Patient presentation: Affected limb is adducted, internally rotated, and significantly flexed at both the hip and knee joints.
* Palpation findings: Femoral head palpable in proximity to the ischial tuberosity; lesser trochanter prominence may be appreciated anteriorly.

Question 5

How do you manage hip dislocations [4]

Answer 5

• ABCDE approach.
• Analgesia
• A reduction under general anaesthetic within 4 hours to reduce the risk of avascular necrosis.
• Long-term management: Physiotherapy to strengthen the surrounding muscles.

Question 6

What are the main causes of anterior and posterior shoulder disclocations [2]

Describe the position the shoulder / arm is in when force occurs [2]

Answer 6

Anterior shoulder dislocation:
- include high-energy sporting collisions and falls; a force to an abducted, externally rotated and extended arm
- occurs when the arm is forced backwards

Posterior dislocation:
- force to the anterior surface of the shoulder, or axial loading of an adducted and internally rotated arm. Due to 3Es:
* Epilepsy - seizures are the most common cause. The dislocation occurs either from a fall itself or from strong muscular contractions that may occur during the clonic phase
* Electrocution
* Ethanol - typically following a fall

Question 7

Label this diagram [5]

Answer 7

Question 8

Label this diagram [5]

Answer 8

Question 9

What sign on an x-ray indicates posterior shoulder dislocation? [1]

Answer 9

The ‘light bulb sign’ suggests a posterior shoulder dislocation (Figure 3). The Y-view can help differentiate between anterior and posterior dislocations.

Question 10

Describe associated fractures that occur in 25% of dislocations [4]

Answer 10

Fractures of the tuberosity or surgical neck:
- these dislocations may not be suitable for closed reduction in the emergency department

Bankart lesions:
- are tears to the anterior portion of the labrum
- these develop when the glenoid labrum is damaged; they may sometimes be associated with an avulsion fracture (bony Bankart)
- These occur with repeated anterior subluxations or dislocations of the shoulder.

Hill-Sachs lesions:
- compression fractures of the posterolateral humeral head
- commonly occurring in anterior dislocations
- shoulder dislocates anteriorly, the posterolateral part of the humeral head impacts with the anterior rim of the glenoid cavity

Reverse Hill-Sachs lesions:
- an impaction fracture of the anteromedial humeral head commonly occurring in posterior dislocations

Question 11

Which type of fracture are labelled as A & B? [2]

Answer 11

A: Hill-Sachs
- compression fractures of the posterolateral humeral head commonly occurring in anterior dislocations
:

B: Bankart

Question 12

What position is the arm in an anterior shoulder dislocation? [2]

Which bony landmark may appear prominent? [1]

Answer 12

Arm position:
* Slightly abducted
* Externally rotated

Acromion process may appear prominent, particularly in slim individuals

Question 13

What position is the arm in an posterior shoulder dislocation? [2]
How does the shoulder change position? [2]
Which bony landmark may appear prominent? [1]

Answer 13

Arm position:
* Adducted
* Internally rotated

Shoulder position:
* The posterior shoulder will appear much more prominent than usual
* The anterior shoulder will appear more flattened than usual

Prominent coracoid process

Question 14

If you had to describe the change in position of the shoulder in an anterior shoulder dislocation - what would it look like? [2]

If you had to describe the change in position of the arm in an anterior shoulder dislocation - what would it look like? [2]

Answer 14

Shoulder:
- loss of rounded appearance (humeral head) and sharp prominence of the acromion (“squaring”)

Arm:
- arm is abducted and externally rotated

Question 15

If you had to describe the change in position of the shoulder in an posterior shoulder dislocation - what would it look like? [2]

If you had to describe the change in position of the arm in an posterior shoulder dislocation - what would it look like? [2]

Answer 15

Arm:
- adducted and internally rotated

Shoulder:
- prominent posterior shoulder and coracoid for acute posterior dislocation

Question 16

What is an Acromioclavicular Joint Injury and how do you differentiate this from a shoulder dislocation? [2]

Answer 16

ACJ injuries involve disruption between the acromion and clavicle - hence they are sometimes referred to as ‘separated shoulders’; Injuries here are most commonly caused by a fall onto or direct blow to the shoulder.

Shoulder dislocations have displaced humeral head from glenoid socket

Question 17

Describe the movements you would conduct to perform a anterior and posterior shoulder dislocation [2]

Answer 17

Anterior dislocation:
- patient sits upright and gentle downward traction is applied to the arm, whilst another person gently rotates the scapula from behind
OR
- arm hangs off the side of the bed and 5-10kg of weight are hung off the arm to provide traction

Posterior dislocation:
- applying axial traction to an adducted arm with the elbow flexed

Question 18

What should you do after performing shoulder joint reduction? [1]

Answer 18

It is important to obtain an anteroposterior and lateral x-ray after reduction techniques have been performed
- This will both confirm that the humeral head has reduced back into the glenoid fossa, as well as to ensure there are no fractures present

Question 19

TOM TIP: Exam questions might challenge you to distinguish between anterior and posterior dislocations.

The answer is almost certainly an [] dislocation unless the patient has had a [2]

Answer 19

TOM TIP: Exam questions might challenge you to distinguish between anterior and posterior dislocations.

The answer is almost certainly an anterior dislocation unless the patient has had a seizure or an electric shock.

Question 20

Describe how the shoulder works and why this results in more anterior dislocations than posterior [2]

Answer 20

Most of our use of shoulder involves outward rotation and abduction of shoulder like in throwing position. Almost all the sports, involves that action.

Now in that position, the humeral head is forcing itself anteriorly and its kept inside the joint firm by contraction of rotator cuff muscles and the ligament restraints of glenoid socket.

Whenever, the force of action overpowers the capability of rotator cuff and shoulder ligaments to restrain shoulder, dislocation occurs.

Very few actions need forcing of humeral head in posterior direction. Hence anterior dislocation is much more common than posterior.

Question 21

Which structure surrounds the glenoid cavity? [1]

Answer 21

The glenoid labrum surrounds the glenoid cavity
- this stabilises the shoulder joi**nt by deepening the socket of the shoulder blade

Question 22

Shoulder dislocations commonly cause axillary nerve damage.

Which nerve roots does the axillary nerve come from? [2]

How does this manifest in a patient?

Answer 22

Axillary nerve damage is a key complication. The axillary nerve comes from the C5 and C6 nerve roots.

Damage causes a loss of sensation in the “regimental badge” area over the lateral deltoid.

It also leads to motor weakness in the deltoid and teres minor muscles (external roation)

TOM TIP: Axillary nerve damage is a common association with anterior dislocations to remember for your exams. This knowledge may be tested in MCQs, where you are asked to identify the nerve, location of sensory loss or muscle affected by weakness.

Question 23

Describe what the following types of shoulder stabilisation surgery are:

• Latarjet procedure
• Remplissage procedure

Answer 23

Latarjet procedure:
- Bone graft using bone from the coracoid process to correct a bony injury to the glenoid rim

Remplissage procedure
- Correcting Hill-Sachs lesions

Question 24

The most common vertebral levels affected are [] followed by []

Answer 24

The most common vertebral levels affected are L5/S1 followed by L4/L5

Question 25

Describe the pathophysiology of a prolapsed disc [3]

Answer 25

Nucleus pulposus losses the mechanical abilities to withstand the pressure and weight of the body.

Annular fibrosis surrounding the nucleus pulposus weakens

A weakening of the posterior longitudinal ligament.

All of the above contributes to the herniation of the nucleus pulposus into the spinal canal.

Question 26

Describe the clinical features of a prolapsed lower disc

Answer 26

95% of prolapsed disc cases are incidental findings and hence asymptomatic.

Remaining 5%:
* Lower back pain (most common complaint).
* Radiculopathy (dependent on the dermatome).
* Neurological weakness.
* Paraesthesia in the affected dermatome.
* Cauda equina symptoms

NB: The severity of the disease does not correlate with the size of the herniated disc on imaging studies.

Question 27

[] test: from 30 to 70 degree (known to be the most sensitive examination for lumbar disc herniation, especially nerve root L4-S1). This will reproduce a shooting electrical sensation down the affected dermatome.

Answer 27

Straight leg test positive from 30 to 70 degree (known to be the most sensitive examination for lumbar disc herniation, especially nerve root L4-S1). This will reproduce a shooting electrical sensation down the affected dermatome.

Question 28

What the is main motion [1] and reflex [1] impacted by an L3 prolapse

What the is main motion [1] and reflex [1] impacted by an L4 prolapse

Answer 28

L3
- Hip adduction
- No reflex affected

L4:
- Knee extension
- Knee jerk affected

Question 29

What the is main motion [1] and reflex [1] impacted by an L5 prolapse

What the is main motion [1] and reflex [1] impacted by an S1 prolapse

Answer 29

L5:
- Ankle dorsiflexion
- No reflex affected

S1:
Feet plantar flexion
* Achilles relfex affected

Question 30

Most prolapsed discs are treated conservatively.

In which scenarios would indicate surgery? [3]
What type of surgery is most commonly used? [1]

Answer 30

Cauda equina (emergency referral to a neurosurgeon)
Progressive neurological weakness
Pain lasting > 6 weeks which does not respond to conservative management

Surgery most commonly used:
- laminectomy + micro-discectomy.

Question 31

Describe the non-surgical treatment of slipped disc [4]

Answer 31

Analgesics (NICE recommend NSAIDs instead of paracetamol as first-line for pain relief)

If radiculopathy is present, NICE recommends the use of the following medications as first-line; amitriptyline, duloxetine, gabapentin or pregabalin.

Corticosteroid epidural injection can be offered in a specialist clinic.

Radiofrequency denervation may be an option in patients with chronic low back pain originating in the facet joints. Radiofrequency is used to target and damage the medial branch nerves that supply sensation to the facet joints associated with the back pain. This is done under a local anaesthetic.

Question 32

Describe the pathophysiology the primary and secondary mechanism of spinal cord injury [2]

Answer 32

Primary Mechanism of Injury:
- Trauma due to compression, contusion, laceration or transection
- immediate neural cell death in the grey matter and axonal damage in white matter tracts
- vascular damage leading to haemorrhage and disruption of blood-spinal cord barrier.

Secondary Mechanism of Injury:
- Inflammation
- Excitotoxicity results from excessive release and impaired reuptake of glutamate
- Apoptosis is triggered by the activation of caspases leading to programmed cell death. This is further augmented by the release of cytochrome C from damaged mitochondria.

Question 33

Describe the clinical features of spinal cord injury [+]

Answer 33

Sudden onset of neurological deficits, primarily motor and sensory dysfunction, which are often associated with pain or discomfort in the back, neck or head

Motor:
* Spasticity: Increased muscle tone leading to stiffness and involuntary spasms.
* Hyperreflexia: Overactive or overresponsive reflexes.
* Babinski sign

Pain

Autonomic Dysregulation:
* Cardiovascular instability: Fluctuations in blood pressure and heart rate due to disruption of sympathetic control.
* Respiratory compromise: Reduced ability to cough or breathe deeply leading to increased risk of respiratory infections.
* Bladder and bowel dysfunction: Incontinence or retention due to loss of voluntary control.
* Sexual dysfunction: Impaired sexual function or fertility issues in both genders.

Spinal shock

Question 34

Describe what is meant by central cord syndrome [1]

What type of injuries cause this? [1]

Answer 34

Central Cord Syndrome:
- More motor impairment in upper than lower limbs along with variable sensory loss; often seen in elderly patients following hyperextension injuries.

Question 35

Describe what is meant by spinal shock [1]

Answer 35

In the acute phase after injury, a state known as spinal shock may occur. This is characterized by flaccid paralysis, loss of reflexes, and loss of sensation below the level of injury

. It is a temporary condition that lasts from several hours to several weeks post-injury.

Question 36

Describe what is meant by Brown-Sequard Syndrome [1]

What type of injuries cause this? [1]

Answer 36

Brown-Sequard Syndrome:
- Ipsilateral motor function loss and contralateral pain/temperature sensation loss; typically caused by penetrating injuries.

Question 37

Describe what is meant by Anterior Cord Syndrome
[1]

What type of injuries cause this? [1]

Answer 37

Anterior Cord Syndrome:
- Loss of motor function and pain/temperature sensation but preservation of proprioception; usually results from anterior spinal artery occlusion.

Question 38

Describe the managment of spinal cord injuries [5]

Answer 38

Acute Resuscitation:
* Maintain airway, breathing, and circulation (ABCs).
Administer oxygen as required to maintain SpO2 ≥94%.
Avoid hypotension (systolic BP should be maintained >90 mmHg).

Steroid Therapy:
* High-dose methylprednisolone can be considered within 8 hours of injury.

Surgical Management:
* Early surgical decompression and stabilisation may improve neurological outcomes in selected patients.

Rehabilitation:
* A multidisciplinary team approach involving physiotherapy, occupational therapy, clinical psychology, dietetics and social work is essential for optimal patient outcomes.

Long-Term Care:
* The management of chronic complications such as pressure sores, urinary tract infections, deep vein thrombosis and autonomic dysreflexia is crucial.

Question 39

Segund fracture is associated with which injury

MCL
LCL
ACL
PCL
Meniscus tear

Answer 39

Segund fracture is associated with which injury

ACL