Abstract
Pain may be asked as part of a viva topic or candidates may be lucky or unlucky enough to have a full 5-minute viva devoted to the topic. It is an important part of orthopaedic practice which is often neglected, but more important now with the push towards day-case surgery and even day-case arthroplasty. Pain is well known to appear as questions in the Part I MCQ/SBA exam.
This viva can be awkward, as bits and pieces such as pain assessment can appear fluffy to orthopods and in real life is best left to the anaesthetists.
Introduction
Pain may be asked as part of a viva topic or candidates may be lucky or unlucky enough to have a full 5-minute viva devoted to the topic. It is an important part of orthopaedic practice which is often neglected, but more important now with the push towards day-case surgery and even day-case arthroplasty. Pain is well known to appear as questions in the Part I MCQ/SBA exam.
This viva can be awkward, as bits and pieces such as pain assessment can appear fluffy to orthopods and in real life is best left to the anaesthetists.
Like genetics, ask examiners about pain and one will get a puzzled look back. Suffice to say, it is not an A-list topic and is most likely a C-list category. Again, similar to genetics, the idea is to score a basic 6 for any question asked. Anything else is a bonus.
One word of caution with C list category topics. With the advent of computer generated curriculum sampling C-list topics are quickly becoming the new A list ones.
Section 5 of the Trs+Orth basic science syllabus can be loosely regarded as the pain section. Four topics about which candidates should demonstrate competency are outlined by the JSCFE.
1. Anaesthesia – principles and practice of local and regional anaesthesia and principles of general anaesthesia.
2. Pain management programmes and management of complex regional pain.
3. Pain and pain relief.
4. Behavioural dysfunction and somatization.
Structured oral examination question 1
Pain
CANDIDATE: An unpleasant sensory and emotional experience associated with actual or potential tissue damage. (International Association of the Study of Pain (IASP)).
COMMENT: The viva could start off awkwardly with a definition that may catch the unsuspecting candidate off-guard. Go for an uncomplicated, straightforward definition that allows you to build on this foundation if you are able to do so.
CANDIDATE: Pain must be assessed using a multidimensional approach, with determination of the following:
Chronicity.
Severity.
Quality.
Contributing/associated factors.
Location/distribution.
Aetiology of pain, if identifiable.
Mechanism of injury, if applicable.
Barriers to pain assessment.
COMMENT: SOCRATES pain mnemonic:
Site – where is the pain?
Onset – when did it start? How long ago?
Character – description: aching, stabbing, burning?
Radiation – where does it go?
Associations – impact on QOL: social, emotional, family, financial.
Time course – does the pain follow a pattern?
Exacerbating/relieving factors.
Severity score – how bad is the pain?
Score 7/8 candidate
Pain scales can be useful.
1. Single dimensional scale
Measures a single dimension of pain, usually pain intensity. Useful in acute pain where the aetiology is clear.
2. Multidimensional scale
These measure the intensity, nature and location of pain, and in some cases, the impact that pain is having on a patient’s activity or mood. Useful in complex or persistent acute or chronic pain.
Visual analogue pain scales are easy for patients to use. Can be either continuous or discrete.
CANDIDATE: With acute pain there is pain of recent onset and probably limited duration. It usually has an identifiable temporal and causal relationship to injury or disease.
Chronic pain persists beyond the time of healing of an injury and frequently there may not be any clear identifiable cause.
CANDIDATE: I am not sure what you mean.
CANDIDATE: Adductor canal block.
COMMENT: For many years a femoral nerve block (FNB) was used as the main peripheral nerve block for postop analgesia following TKA. One major issue with FNB is quadriceps weakness, which can significantly affect early physiotherapy input and thus interfere with rapid recovery programmes following TKA.
Adductor canal block is a pure sensory nerve block for postop analgesia. The saphenous nerve (sensory nerve) and part of the obturator nerve travelling through the adductor canal of thigh are targeted with local anaesthetics injected into the canal to provide adequate analgesia by blocking these nerves. The block is performed under ultrasound guidance.
This block seems to work well without causing quadriceps weakness.
The candidate should have expanded on their answer if able to do so.
EXAMINER: That’s for knee replacements. Anything else?
EXAMINER: OK, tell me about this.
CANDIDATE: This is a national patient safety initiative aimed at reducing the incidence of inadvertent wrong-sided nerve block during regional anaesthesia. It reduces the chance of a never event occurring.
EXAMINER: What is a never event?
CANDIDATE: The National Patient Safety Agency (NPSA) describes a ‘never event’ as a serious, largely preventable patient safety incident that should not occur if the available preventative measures have been implemented.
EXAMINER: Have you heard of the sufentanil sublingual tablet system?
CANDIDATE: No.
COMMENT: The sufentanil sublingual tablet system is pre-programmed to dispense a single tablet, when the unique radiofrequency adhesive tag wrapped around the patient’s thumb is activated. It provides an alternative option to IV morphine PCA for some people with moderate to severe acute postoperative pain.
Its use is restricted to acute moderate to severe postoperative pain, in the hospital setting and for a maximum duration of 72 hours. It is a user-friendly device that is especially useful in patients for whom improved mobility is an advantage.
CANDIDATE 1: In my hospital we don’t have the set up for this.
COMMENT: This is a gift question if you have done a bit of homework.
CANDIDATE 2: Enhanced recovery is multidisciplinary standardized perioperative care aimed at early mobility, discharge and return to normal life with both reduced morbidity and potentially mortality.
The strategy has four strands:
1. Improving preoperative care.
2. Reducing the physical stress of the operation.
3. Decreasing postoperative discomfort.
4. Improving postoperative mobility.
EXAMINER: You have mentioned ERAS, but what about day-case surgery?
CANDIDATE 2: This would involve preoperative patient education and motivation for the programme. Anaesthesia should be standardized and would typically involve a low-dose spinal and sedation or light GA, local anaesthetic infiltration, IV paracetamol and use of tranexamic acid.
Perioperative measures would include adequate postop analgesia, physiotherapy, a blood transfusion protocol, standardized discharge medications and arrangements for a nurse specialist to check on the patient to make sure they are safe when discharged.
EXAMINER: Anything else?
CANDIDATE: Sorry.
Structured oral examination question 2
Managing neuropathic pain
EXAMINER: What do we mean by neuropathic pain?
CANDIDATE: Neuropathic pain arises from damage, or pathological change, in the peripheral or central nervous system.
Neuropathic pain is defined by the IASP as ‘pain initiated or caused by a primary lesion or dysfunction in the nervous system’.
EXAMINER: How is neuropathic pain different to nociceptive pain?
CANDIDATE: Nociceptive pain is caused by actual tissue damage, whereas neuropathic pain is produced either by damage to or pathological change in the peripheral or central nervous system, the system that normally signals pain.
EXAMINER: And?
CANDIDATE: The mechanisms of neuropathic pain differ significantly from nociceptive pain.
For example, there is:
A lower threshold for activation of injured primary afferents causing ectopic discharges from the injured nerve or the dorsal root ganglion.
There is downregulation of dorsal horn opioid receptors and reduced opioid sensitivity.
Wind up occurs, that is increased activity of glutamate in the dorsal horn which increases the response to C fibre stimulation.
EXAMINER: Can you give examples of neuropathic pain?
CANDIDATE: Common neuropathic conditions affecting the peripheral nervous system include peripheral diabetic neuropathic pain (PDNP), postherpetic neuralgia (PHN), AIDS polyneuropathy, cervical or lumbar radiculopathy, mechanical compression such as entrapment syndromes (e.g. carpal tunnel syndrome), phantom limb pain after amputation, trigeminal neuralgia and traumatic nerve injury.
Central causes for neuropathic pain include spinal cord injury (SCI), multiple sclerosis (MS) and stroke leading to central post stroke pain (CPSP).
EXAMINER: How does neuropathic pain present?
CANDIDATE: Patients usually complain of dysaesthesias (unpleasant and strange sensations in the skin (tingling, pins and needles)), deep-seated gnawing pain, and abnormal thermal sensations (burning, on fire).
Less commonly, paroxysmal pains such as shooting, stabbing, or electric shocks.
Patients may also complain that the painful area is abnormally sensitive to any innocuous mechanical or thermal stimulus; such as clothes brushing against the area being intensely painful.
CANDIDATE: Nerve pain can be difficult to treat, as standard treatment with conventional analgesics does not typically provide effective relief of pain.
I would use a step-wise ladder:
1. Non-opioid analgesic/basic analgesia paracetamol 1 g QDS. Unlike most other types of pain, neuropathic pain doesn’t always respond well to these common painkillers. Higher doses may be better at managing the pain, but are also more likely to cause side effects.
2. Tricyclic antidepressant (TCA). Amitriptyline. TCAs block the reuptake of noradrenaline and serotonin. The pain-relieving effect of TCAs is independent of their antidepressant effect. The most common adverse events include sedation, anticholinergic side effects (namely dry mouth, constipation and urinary retention) and orthostatic hypotension. TCAs can cause or exacerbate cognitive impairment and gait disturbances in elderly patients and may predispose them to falls. They are associated with cardiac toxicity and must be avoided in the elderly and in those with cardiac pathology. They offer moderate relief of neuropathic pain.
3. Anticonvulsant gabapentin. If TCA is contraindicated or there is lancinating pain (electric shock or stabbing). Proposed mechanism of action is the interaction with the voltage-gated calcium channel alpha‐2‐delta subunit.
4. Tramadol. Can be used to treat resistant neuropathic pain. Side effects include nausea and vomiting, dizziness and constipation.
5. Secondary pain care referral. Indicated if pain persists or remains uncontrolled.
Treating any associated anxiety or depression may reduce the need for analgesics.
Structured oral examination question 3
WHO pain ladder
EXAMINER: Your clinic patient has osteoarthritis of the knee. Referred in for a knee replacement, but symptoms aren’t severe enough yet for surgery. How would you control his knee pain?
CANDIDATE: I would prescribe him morphine.
EXAMINER: Are you sure?
CANDIDATE: Yes. Morphine is a good choice for pain control.
EXAMINER: What is the WHO pain ladder?
CANDIDATE 1: I have heard of it, but I am not sure.
CANDIDATE 2: The WHO pain ladder was originally introduced as a framework for treating cancer pain in 1986 with modifications in 1997.
Treatment of pain should begin with a non-opioid medication. If the pain is not properly controlled, one should then introduce a weak opioid. If the use of this medication is insufficient to treat the pain, one can begin a more powerful opioid. One should never use two products belonging to the same category simultaneously. The analgesic ladder also includes the possibility of adding adjuvant treatments for neuropathic pain or for symptoms associated with cancer.
The WHO guidelines can be used for all patients with either acute or chronic pain who require analgesia.
Although there has been a number of criticisms due in part to omissions, developments of new techniques and medications, the WHO treatment guidelines are still considered a valid tool to use.
EXAMINER: What are the five recommendations of the WHO ladder?
CANDIDATE 2:
1. Analgesics should be administered orally, wherever possible.
2. Analgesics should be given at regular definite intervals.
3. Analgesics should be prescribed according to pain intensity.
4. The dosing of medication should be adapted to the individual. The correct dosage is one that will allow adequate pain relief.
5. The patient should be given all the necessary information about when and how to administer the medication.
Structured oral examination question 4
Complex regional pain syndrome
EXAMINER: You meet a patient in clinic complaining of severe pain in a wrist preventing them from using it normally after a fracture. It is unrelenting pain, keeping them awake at night, associated with swelling, temperature and skin changes, and light touch provokes severe pain. What are your thoughts?
COMMENT: This is a giveaway diagnosis of CRPS.
CANDIDATE: These features are very suggestive of complex regional pain syndrome. I would like to take a fuller history and examine the patient to confirm my initial provisional diagnosis.
EXAMINER: The patient is a female, 43 years old, right-hand dominant secretary who sustained a straightforward undisplaced fractured radius 10 weeks ago after a fall. Managed conservatively in a Colles’ cast.
CANDIDATE: Examination wise I would examine to see if the wrist was red or swollen. I would assess if they hold their limb protectively and if wrist movements were severely restricted and painful.
I would order AP and lateral radiographs of the wrist and look to see if diffuse patchy osteopenia was present.
EXAMINER: What is complex regional pain syndrome?
CANDIDATE: Complex regional pain syndrome is a syndrome associated with severe pain in a distal limb with associated peripheral sensory, vasomotor, sudomotor/oedema and motor/trophic changes.
EXAMINER: How is it diagnosed?
CANDIDATE 1: Diagnosis is based on clinical history and examinations. Investigations can be used as adjuncts.
COMMENT: This is a score 5/6.
CANDIDATE 2: Diagnosis is based on clinical history and examinations. Investigations can be used as adjuncts. However, it is very much a diagnosis of exclusion. It is important to exclude other causes of pain such as fracture malunion or non-union, post-traumatic arthritis, infection, peripheral vascular disease in any patient who develops a red, hot and swollen or cold and poorly perfused limb after a fracture or surgery.
EXAMINER: Any other differentials you need to consider?
CANDIDATE: Diabetic polyneuropathy may also present with pain, skin colour changes and motor deficit.
EXAMINER: Do you know any criteria?
CANDIDATE: No, sorry.
COMMENT: The Budapest Criteria (specificity 0.69) allow a clinical diagnosis to be made on the basis of a combination of symptoms and signs seen in four clinical categories.
The patient has continuing pain that is disproportionate to any inciting event.
The patient has at least one sign in two or more categories below.
The patient reports at least one symptom in three or more categories below.
No other diagnosis can better explain the signs or symptoms.
| Category | Symptoms |
|---|---|
| Sensory | Reports of allodynia and/or hyperalgesia |
| Vasomotor | Reports of temperature asymmetry and/or skin colour changes and/or asymmetry |
| Sudomotor/oedema | Reports of oedema and/or sweating changes and/or sweating asymmetry |
| Motor/trophic | Reports of decreased ROM and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin) |
| To fulfil diagnostic criteria patients must report at least one symptom in three of the four categories | |
EXAMINER: What is the natural history of CRPS?
CANDIDATE: After a year, around half of patients affected will fully recover while the other half may complain of some residual stiffness and pain. A very small number of patients will continue to have significant disabling symptoms which can become chronic in nature.
EXAMINER: What is the pathophysiology of CRPS?
CANDIDATE: It is thought that CRPS develops when persistent noxious stimuli from an injured body region leads to peripheral and central sensitization, whereby primary afferent nociceptive mechanisms demonstrate abnormally heightened sensation, including spontaneous pain and hyperalgesia.
EXAMINER: What do you mean by a noxious stimulus?
CANDIDATE: This is a stimulus that is damaging to normal tissues.
CANDIDATE: This is a receptor preferentially sensitive to a noxious stimulus or to a stimulus which would become noxious if prolonged.
EXAMINER: How are nociceptors activated?
CANDIDATE: Peripheral activation of nociceptors is modulated by a number of chemical substances, which are produced and released when there is cellular damage (e.g. potassium, serotonin, bradykinin, histamine, prostaglandins, leukotrienes and substance P).
These substances influence the degree of nerve activity and intensity of the pain sensation.
EXAMINER: What are the current approaches to management?
CANDIDATE 1: A recent paper demonstrating level I evidence looked at the use of antioxidant vitamin C. A dose of 500 mg a day for 50 days was shown to reduce symptoms of CRPS.
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