Orthopaedics

Question 1

You are asked to see a patient in the outpatients clinic. The patient has weakness in her left arm following a car accident 1 month ago when she fractured her left arm. On examination there is weakness of extension of the fingers and wrist on the left side. However, sensation is maintained in all distributions and there is no wrist drop. Which one of the following fractures classically associated with nerve damage is the most likely cause of this palsy?
A. Fracture of head of radius
B. Fracture of shaft of humerus
C. Medial epicondyle of humerus
D. Fracture of shaft of ulna
E. Fracture of neck of femur

Answer 1

A. Fracture of head of radius

Option (E) is just making up the numbers here and should be ignored.

Of the other options we need to know the anatomy of the radial nerve (the nerve affected here). The radial nerve winds around the shaft of humerous before entering the forearm laterally and running adjacent to the head of the radius. Options (C) and (D) are incorrect for this reason as they refer to the medial aspect of the arm. Medial epicondyle fractures are associated with ulnar nerve palsies.

Options (A) and (B) could both lead to a radial nerve palsy, the difference is in knowing the clinical pattern that would be expected. With a disruption of the nerve at the humeral shaft there would be a palsy affecting the branches of the radial nerve, including the sensory branch, the superficial radial nerve. In this case we see that sensation is preserved and so the damage must be distal to the branches of the radial nerve, specifically affecting the posterior interosseous nerve, making this a head of radius fracture (A).

Question 2

On assessment of a patient in the outpatients department you identify that they are Trendelenburg’s test positive. This indicates a possible palsy of which nerve?
A. Sciatic
B. Femoral
C. Obturator
D. Superior gluteal
E. Inferior gluteal

Answer 2

D. Superior gluteal

A positive trendelnberg test/gait arises from a weaknes of the hip abductors, this results in the contralateral hip dropping when the leg is raised. It can arise due to an abnormality of the muscle, the nerve or the connections between. The most common cause is muscle wasting in patients with degenerative joint disease or chronic hip pain. Other causes may be iatrogenic muscle damage, structural joint disease, and neuromuscular diseases (Polio, Guillian-Barre).

The nerve supply to gluteus medius and minimus (the hip abductors) is via the superior gluteal nerve (D), so that is our answer here.

The inferior gluteal nerve (E) supplies gluteus maximus, and may become damaged in surgery or trauma due to its location in close apposition to the greater trochanter.

Question 3

The most common cause of an acquired valgus deformity of the knee joint is:
A. Rheumatoid arthritis
B. Osteoporosis
C. Trauma
D. Osteoarthritis
E. Osteomalacia

Answer 3

D. Osteoarthritis

There is an old concept favoured in examinations that OA predominantly causes a valgus deformity (D) whereas RA (A) predominantly causes a Varus deformity. It is rarely used in clinical practice as it doesn’t always hold true. The addage is based on the fact that OA more commonly affects the medial compartment, and the inverse is true of RA. Both diseases can affect either/both of the compartments but as OA is so much more common it is certainly the answer to this question.

Question 4

Which of the following is the most common secondary cause of haemarthrosis of the knee?
A. Meniscal tear
B. Anterior cruciate ligament injury
C. Osteophyte fracture
D. Posterior cruciate ligament injury
E. Patella dislocation

Answer 4

B. Anterior cruciate ligament injury

Haemarthrosis may be primary or secondary, a primary results from a spontaneous bleed that may be due to a coagulation disorder or warfarin. Secondary haemarthrosis is due to trauma.

An injury to the anterior cruciate ligament (B) will cause a rapid build up of blood within the joint and accounts for 80% of traumatic haemarthrosis. Posterior cruciate ligament injury (D) is less associated with haemarthrosis.

Patella dislocation (E) and meniscal tear (A), where the tear extends into the peripheral third of the cartilage where there is a vascular supply, each account for 10% of haemarthrosis.

Oesteophyte fracture (C) is an important cause of haemarthrosis but is less common than the other causes here.

Question 5

Which of the following options is not a clinical feature common to osteoarthritis
and rheumatoid arthritis of the knee?
A. Muscle wasting
B. Joint effusion
C. Baker’s cyst
D. Raised C-reactive protein
E. Subcutaneous nodules

Answer 5

E. Subcutaneous nodules

Both diseases involve an inflammatory process that is a divergent response to joint injury and cartilage repair, as such joint effusion (B), synovitis and raised inflammatory markers (D) are common to both.

As the degenerative process common to both progresses there can be the development of a Baker’s cyst (C), although rupture is more classically associated with active RA.

Muscle wasting (A) is a result of local inflammation and reduced use of the joint due to pain, and so is another common feature. Of interest, the vastus medialis is the first to atrophy due to disuse.

The difference is that RA is a systemic disease process and so has extra articular manifestations. One such manifestation are the subcutaneous ‘rheumatoid nodules’ (E), in OA there are heberden’s nodes which are periarticular bony nodules.

Question 6

Rheumatoid arthritis is a multisystem connective tissue disease. Which of the
following is not a pulmonary complication of rheumatoid arthritis?
A. Effusion
B. Obstructive lung disease
C. Restrictive lung disease
D. Cavitation
E. Emphysema

Answer 6

B. Obstructive lung disease

RA is a systemic disease with a huge rage of extrarticular manifestations, including occular, cutaneous, pulmonary, cardiovascular and haematological complications.

The pulmonary complications of RA can result in fibrosis leading to restrictive lung disease (C), other manifestations are also possible, around 5% will experience pleuritis with chest pain and exudative effusions (A). Pulmonary nodules also occur (these are histologically similar to cutaneous nodules), they may cavitate (D). In the presence of
pneumoconiosis, pulmonary nodules may cause large cavitating lesions
(Chaplin’s syndrome) with associated respiratory compromise, but this is
becoming increasingly rare in the UK following the collapse of the mining
industry and improved health and safety on industrial sites.

The most common pulmonary manifestation of RA, however, is an obstructive lung disease (B), accounting for 30-50% of all pulmonary manifestations. Patients present with wheeze and exertional dyspnoea in a similar clinical picture to COPD but with an underlying bronchiolitis not emphysema (E).

Question 7

All of the following are dermatological manifestations of rheumatoid arthritis,
except:
A. Palmar erythema
B. Erythema nodosum
C. Pyoderma gangrenosum
D. Livedo reticularis
E. Skin nodules

Answer 7

B. Erythema nodosum

Of the list of conditions here, erythema nodusum (B) is the only one not associated with RA.

Question 8

Dupuytren’s contracture is caused by a thickening of the palmar fascia. It is
associated with the following conditions, except:
A. Alcoholic cirrhosis
B. Peyronie’s disease
C. Acquired immune deficiency syndrome
D. Epilepsy
E. Syphilis

Answer 8

E. Syphilis

Dupuytren’s contracture is a deformity caused by thickening of the palmar fascia leading to fixed finger flexion. The differentials include skin fibrosis (evidence of previous scarring), tendon fibrosis and ulnar nerve palsy. A pathognomic feature of dupuytren’s are Garrod’s pads, these are areas of thickened subcutaneous tissue over the PIP joints. The exact cause of Dupuytren’s is unknown. Although it is most commonly idiopathic, it is associated with systemic conditions as the mnenomic ‘ABCDEF’ demonstrates;

• AIDS
• ‘Bent penis’: Peyronie’s disease is fibrosis of the corpus cavernosum,
seen in 3 per cent of Dupuytren’s
• Cirrhosis – particularly alcoholic liver disease
• Diabetes mellitus
• Epilepsy and anti-epileptic medication (particularly phenytoin)
• Familial (autosomal dominant)
• Fibromatoses – a group of disorders characterized by diffuse
fibrosis. A patient may develop each in isolation, or may develop
several over the course of their life. Such conditions include
Reidel’s thyroiditis, retroperitoneal fibrosis, Ledderhose disease and
desmoid tumours.

Question 9

Your registrar tells you that his patient has a boxer’s fracture. From this, you know
that the bone which is fractured is:
A. The fifth metacarpal
B. The fourth metacarpal
C. The fifth proximal phalanx
D. Hamate
E. Styloid process

Answer 9

A. The fifth metacarpal

A boxer’s fracture is a fracture to the fifth metacarpal bone, so called
because it typically occurs when a closed fist strikes a solid surface.

The other most commonly asked about fractures;
Colles’,

Smith’s,

Barton’s,

Monteggia’s

Galeazzi’s

Question 10

Which one of the following intrinsic muscles of the hand is not innervated by the
median nerve?
A. First lumbrical
B. Abductor pollicis brevis
C. Opponens pollicis
D. Adductor pollicis
E. Flexor pollicis brevis

Answer 10

D. Adductor pollicis

The median nerve motor supply can be remembered by ‘LOAF’

• Lumbricals (first and second)
• Opponens pollicis
• Abductor pollicis brevis
• Flexor pollicis brevis

All other intrinsic muscles of the hand are supplied by the ulnar nerve, such as Adductor pollicis (D).

In clinical practice it is good to bear in mind that the nerve supply to flexor pollicis is variable, the lubricals are difficult to test and opponens pollicis is assisted by other muscles. This means in practic that the best way to assess the motor component of the median nerve is to test abductor pollicis brevis by raising the thumb to the celing on an upturned palm.

Moving on, assesing motor function of the ulnar nerve is achieved with the palmar interossei (finger adduction), and the radial with finger extension at the MCP joint.

Question 11

All of the following are causes of carpal tunnel syndrome, except:
A. Hypothyroidism
B. Amyloidosis
C. Diabetes
D. Gout
E. Rheumatoid arthritis

Answer 11

C. Diabetes

Carpal tunnel is a nerve palsy secondary to compression in the narrow carpal tunnel. This chronic compression impairs blood flow to the nerve fibres and leads to fibrosis and impaired conduction.

Clinically the patient will pesent with altered sensation, aching pain (especially at night) and muscle weakness and wasting affecting the thenar emminence.

It affects women more frequently than mes, and is most commonly idiopathic. Secondary causes include conditions where the carpal tunnel becomes compromised;

• anatomical abnormalities – deformity following previous fracture
• soft tissue proliferation – obesity, lipoma, ganglion, acromegaly, amyloidosis
• inflammation – RA, gout
• fluid balance aberration – pregnancy, menopause, hypothyroidism,renal failure.

Peripheral neuropathies may affect the median nerve and so mimic carpal tunnel, but as the mechanism is not compressive they are not a form of carpal tunnel.

Question 12

Which of the following pathological changes is not a feature of rheumatoid disease
of the hand?
A. Boutonnière’s deformity
B. Z line thumb
C. Squaring of the thumb
D. Ulnar deviation
E. Swan-neck deformity

Answer 12

C. Squaring of the thumb

Squaring of the thumb (C), Heberden’s nodes (DIP joints), and Bouchard’s nodes (PIP joints) are all features of osteoarthritis.

The possible signs of RA in the hands are listed below;

• Z thumb – flexion of the interphalangeal joint with hyperextension
of MCPJ
• fixed ulnar deviation of fingers – as opposed to Jaccoud’s deformity
in SLE, where fingers appear normal in extension but ulnar
deviation occurs on flexion
• swan-neck deformity – due to fibrosis of the interosseous and
lumbrical muscles, forcing a hyperextension of PIPJ and flexion of
DIPJ
• Boutonnière deformity – due to trapping of a flexed PIPJ through a
rupture in the central portion of the extensor tendon expansion,
resulting in fixed flexion of the PIPJ and hyperextension of DIPJ.
• radial deviation of the wrist
• volar subluxation of the wrist
• volar subluxation of the MCPJs.

Question 13

A patient presents to his GP surgery complaining of a swelling on his wrist. On
examination, there is a focal swelling on the dorsal aspect of the wrist. It is smooth
and non-tender. The overlying skin is normal and moves freely over the mass,
however, it seems to be fixed to the tendon. What is the likely diagnosis?
A. Sebaceous cyst
B. Lipoma
C. Ganglion
D. Giant cell tumour of the tendon sheath
E. Fibroma

Answer 13

C. Ganglion

In this case the lump is not fixed to the skin so we can be sure that it is not a sebaceous cyst (A). With a lipoma (B) the lump would be within the fat layer, so being fixed to the tendon excludes that possibility.

Of the remaing options they are difficult to differentiate clinically but fibromas (E) and giant cell tumours (D) are very rare, making a ganglion the most likely possibility (C).

A ganglion is a cystic degeneration of fibrous tissue, they occur most commonly around joints and tendon sheaths. They are not degeneations or projections of synovial membranes. 90% of ganglia occur in association with the wrist joint and tendons of the hand.

Question 14

A patient presents to the outpatients department following referral for carpal
tunnel syndrome. While taking the history and examining the patient you attempt
to evaluate whether any permanent nerve injury has occurred. Which sign is often
the first indicator of lasting nerve injury?
A. Pins and needles
B. Thenar muscle wasting
C. Night pain
D. Reduced two-point discrimination
E. Positive Phalen’s test

Answer 14

D. Reduced two-point discrimination

Chronic compression in carpal tunnel syndrome leads to fibroblast proliferation and impairment of nerve function. The common early symptoms include night pain (C) and pins and needles (A), these are due to ischaemia of the nerve axon and are reversible.

A positive Phalen’s test (E) indicates that the median nerve is susceptible to compression but gives no indication of any lasting damage.

Loss of two point discrimination (D) is a sign of loss of nerve fibres which is rarely completely reversible. Muscle wasting (B) is a late sign of irreversable nerve damage.

Question 15

Which of the following muscles is not part of the rotator cuff?
A. Pectoralis minor
B. Subscapularis
C. Supraspinous
D. Teres minor
E. Infraspinous

Answer 15

A. Pectoralis minor

Question 16

A patient presents with symptoms suggestive of adhesive capsulitis (frozen shoulder). Which of the following systemic conditions is most commonly associated with this?

A. Fibrotic lung disease

B. Systemic lupus erythematosus

C. Sjögren’s syndrome

D. Osteoarthritis

E. Diabetes

Answer 16

E. Diabetes

Adhesive capsulitis is an uncommon condition where fibrotic contracture anround the glenohumeral jont restricts movement. It is a linical diagnosis with three classically described phases; an initial painful phase, a painless ‘locked’ phase, and a resoloution phase. These phases will occur, typically, over several months in sequence. Histologically there is similarity on the fibrotic changes sen in Dupuytren’s and there is a strong correlation betwen the two conditions. Adhesive capsulitis is classically associated with diabetes mellitus, although the pathophysiology is unknown.

Question 17

A patient with longstanding osteoarthritis presents with pain on movement of his shoulder. You perform a full shoulder exam. You note that you can re-create the pain by asking the patient to abduct his shoulder against resistance. You conclude that there is impingement of which one of the following structures?

A. Teres minor

B. Supraspinatus

C. Infraspinatus

D. Subscapularis

E. Subacromial bursa

Answer 17

B. Supraspinatus

The ligaments of the four rotator cuff muscles pass through the narrow coracoacromial arch. This arch is formed by the coracoid process, the anterior third of the acromion and the coracoacromial ligament. The ligaments are afforded a degre of protection from friction by the subacromial bursa. Degenerative diseases such as osteoarthritis commonly narrow this space leading to rubbing of the tendons against bony structures and leading to inflammatory pain.

Supraspinatous (B) is the most commonly affected tendon, this classically results in pain of shoulder abduction against resistance.

Testing of the other muscles is possible, infraspinatous (C) can be tested on resisted lateral rotation , subscapularis (D) causes pain on resisted medial rotation, teres minor (A) is rarely involved. Pain across all ranges of movement indicates subacromial bursitis (E).

Question 18

A 37-year-old patient presents to you having noticed a lump on the lateral aspect of his leg. The lump was first noticed while the patient was in the gym on a rowing machine. There is no associated pain. On examination when the patient tenses his quadriceps a smooth lump can be appreciated, which disappears when the leg is relaxed. With the leg relaxed, it is possible to identify a depression in the fascia lata. The diagnosis is:
A. Intramuscular haematoma
B. Partial quadriceps rupture
C. Muscle hernia
D. Intermuscular lipomata
E. Myosarcoma

Answer 18

C. Muscle hernia

An intramuscular haematoma (A) is a collection of blood around an injured muscle.it is typically painful and restricts movement. On tensing the haematoma will become more painful and less prominent due to compression by overlying muscle tissue.

A muscle rupture (B) normally occurs in two groups of patients; the atheletes, where it is a sudden, often painful injury. And the elderly patients where ii is a degnerative process and the injury leading to rupture may not be noticed. The muscle tear will typically not be palpable when the muscle is relaxed but will become prominent on contraction.

A muscle hernia (C) is the extrusion of muscle fibres through a defect in the fibrous sheath. It most commonly occurs in the thigh. The hernia becomes more prominant on contraction and less so on relaxation. The defect in the sheath may be evident when the muscle is relaxed.

Intramuscular lipomata (D) are lipomas occuring within the muscle bulk, they may be painful or painless, and may become more or less prominant on contraction depending on thier position in the muscle. However, they rarely occur in the limbs and are most common on the trunk.

Myosarcoma (E) are rare primary muscle tumours and are predominantly seen in old age.

Question 19

Out of the following bone pathologies, which is not correctly matched to the most
common site at which it occurs?
A. Enchondroma – bones of hands and feet
B. Osteoma – cranial vault and skull
C. Ewing’s sarcoma – mid-shaft femur
D. Osteosarcoma – femur, just above the knee
E. Osteomyelitis – mid-shaft long bone

Answer 19

E. Osteomyelitis – mid-shaft long bone

Question 20

A 19-year-old man presents, having noticed a hard lump above his knee. He
initially noticed the lump 3 years ago but presents now after his girlfriend
persuaded him to find out what it is. He does not complain of any associated
symptoms. Radiographic investigation demonstrates a knob of bone on the surface of the distal femur, which projects away from the knee joint. The most likely diagnosis is:
A. Ossification of quadriceps tendon
B. Exostosis
C. Enchondroma
D. Osteoma
E. Osteosarcoma

Answer 20

B. Exostosis

With a slow growing and asymptomatic lump we know that osteosarcoma (E) is less likely. Although osteosarcomas commonly occur just above the knee they would present with pain and rapid growth, which is not seen here. On examination a firm mass would be felt, the mass is often warm and a bruit may be heard.

Enchondroma (C) is a benign cartiladge growth within the bone, most commonly in the hands and feet. This is precluded in this case by the radiograph and clinical picture.

Osteomas (D) are benign, slow growing tumours that most commonly occur in the forehead or cranial vault. That is not the case here.

The quadriceps tendon inserts into the patella and so calcification of the tendon (A) would not be seen above the knee.

The findings here, both radiological and clinical are consistent with a diagnosis of exostosis (B). This is when there is an disruption during development leading to the separation of a small piece of metaphyseal cartilage becoming separated from the growth plate. It will continue to develop in it’s abnormal location and will develop into a bony knob on the side of the bone, typically pointing away from the joint. They are usually asymptomatic but may interfere with joint or muscle funcion.

Question 21

Which one of the following statements regarding Paget’s disease of bone is not
correct?
A. It most commonly occurs in the pelvis
B. It more commonly affects a single bone
C. It occurs in 3 per cent of all individuals over 40 in the UK
D. Characteristic biochemical findings include raised serum alkaline
phosphatase, normal calcium and normal phosphate
E. 1 per cent of cases will develop osteosarcoma

Answer 21

B. It more commonly affects a single bone

Paget’s disease of the bone is a common (3% incidence)(C) condition which is unsymptomatic in the majority of cases. Symptoms include bony pain, fracture and deformity, deformity is due to bone overgrowth and may present as had enlargement (osteoporosis circumscripta) and long bone bowing and enlargement (sabre tibia). Complications include nerve
compression within bony channels (particularly cranial nerves, spinal
cord), fracture, high-output cardiac failure (due to increased bone
vasculature necessitating increased cardiac output) and sarcomatous
change, which will affect 1 per cent of cases (E)

Only 15% of cases are mono-ostotic (B), the vast majority are polyostotic affecting most commonly; the pelvis, lumbar spine, femur, thoracic spine, sacrum, skull, and tibia, in decreasing frequency. Diagnosis is based on characteristic biochemical and radiological findings (D).

Question 22

Looser’s zones (also known as pseudofractures) are a radiographic feature
characterizing which one of the following bone diseases?
A. Osteomalacia
B. Osteoporosis
C. Gout
D. Paget’s disease
E. Osteomyelitis

Answer 22

A. Osteomalacia

Osteoporosis (B) is an age-related loss bone mass with cortical thinning and loss of trabeculae. It is difficult to identify on a plain film, but certain fracture patterns typify this condition, such as vertebral crush fractures. Confirmation is by dexa scan.

Gout (C) is typified by soft tissue gouty tophi, with punched-out lesions away from the joint line seen on plain film radiographs.

Paget’s disease (D) is a disorder of bone turnover with variable radiographic features, they can include lytic and sclerotic lesions with course irregular trabeculae.

Osteomyelitis (E) may show no abnormalities on radiographs, 50% will have lifting of the periosteum (representing a subperiosteal abcess), in the later stages sclerotic lesions may be seen.

Osteomalacia (A) is a disease of reduced bone quality, the mass is nomal. It occurs secondarily to ineffective miniralisation of the matrix, which can be due to; dietary deficiency, abnormal uptake (GI pathology), abnormal metabolism (renal or hepatic pathology) or the actions of certain drugs (phenytoin, phenobarbitol).

The loss of cortical bone and failure of miniralisation result’s in teh radiographic apperance of Looser’s zones, radiolscent lines through the cortex, which appear like non displaced partial fractures (psudo-fractures).

Question 23

According to the current National Institute for Health and Clinical Excellence
guidelines all of the following are indications for use of bisphosphonates in the
treatment of osteoporosis, except:
A. Any patient with a fracture over the age of 65
B. Any patient with a fracture aged 65–75 and a T score less than –2.5
C. Any patient with a fracture aged <65 and a T score less than –3.0
D. Any patient taking high-dose systemic steroids for more than 3 months
with a T score less than –1.3
E. Any smoker with a fracture aged <65 and a T score less than –2.5

Answer 23

A. Any patient with a fracture over the age of 65

Osteoporosis is an extremely common condition leading to 1 in 3 women and 1 in 12 men having a fracture, secondary to osteoporosis, by the age of 90. The WHO defines oseoporosis as a Bone mineral density score (BMD or T-score) less than 2.5 standard deviations below the mean. Those with a T-score of -1 to -2.5 are classed as having osteopenia.

The NICE guidelines recommend bisphosphonates in all of the above circumstances except (A), the guidelines recommend bisphosphanates for any patient over 75 who suffers a fracture, below that age treatment is guided by DEXA scans.

Prophyklactic bisphosphonates are also used in those recieving >7.5mg steroids daily for greater than three months.

In those under 65, bisphosphonates are only indicated if T score is less
than –3.0 or less than –2.5 with an identified risk factor for osteoporosis.
Risk factors include: smoking, steroids, sedentary lifestyle, poor diet,
alcohol, liver cirrhosis, hyperthyroidism/hyperparathyroidism, early
menopause, amenorrhoea >6 months in women and hypogonadism in
men. Anorexia nervosa is another common risk factor, with risk
increasing once BMI <19 kg/m2.

Question 24

A 10-year-old African Caribbean boy is referred to the orthopaedic team with an acutely painful arm. On examination there is a notable swelling of the limb above and around the elbow joint. There is no reduced range in passive movement of the joint but the boy is holding his arm very still and will not actively move the limb. Investigations include haemoglobin 8.3 g/dL, white cell count 10.5 x 109/L, C-reactive protein 12 mg/L. The child is apyrexial with a blood pressure of 110/75 mmHg, and a pulse rate of 85 beats/min.
A. Septic arthritis
B. Osteomyelitis
C. Bony infarct
D. Gout
E. Juvenile arthritis

Answer 24

C. Bony infarct

Question 25

Which one of the following organisms is most commonly associated with septic
arthritis?
A. Gram –ve bacilli
B. Haemophilus influenzae
C. b-haemolytic streptococci
D. Streptococcus pneumoniae
E. Staphylococcus aureus

Answer 25

E. Staphylococcus aureus

Septic arthritis is an infection of a synovial joint, diagnosed on clinical suspicion. In cases of uncertainty a joint aspiration may be useful, but i clinical suspicion is high nothing should delay arthroscopic washout and blood cultures. IV antibiotics should be started as soon as cultures have been taken, the joint should be splinted for 48hrs. Joint sepsis occurs secondary to other sources of infection such as; UTI, LRTI, Cellulitis/abcess of intravenous drug use.

Most commonly Staphylococcus aureus (E), which accounts for around 60% of septic arthritis.

beta-haemolytic strep (C) accounts for 15%,

gram negative organisms (A) account for 17%, usually secondary to GI infection, biliary sepsis, or UTI.

Strep pneumoniae (D) is only 3% of cases

Haemophilus influenzae is more coomon in children under 3, but witht he use of the vaccine is now relatively rare.

Question 26

Which of the following conditions/factors does not predispose to gout?
A. Lesch–Nyhan syndrome
B. Psoriasis
C. Aspirin
D. Xanthine oxidase deficiency
E. Alcohol

Answer 26

D. Xanthine oxidase deficiency

Uric acid is a breakdown product of purine metabolism, it is usually ionised within the body and only when there is an excess of uric acid does it become crystalised (monosodium urate). This becomes deposited as crystals in the joints, soft tissues, and renal tubules. Several genetic disorders affect purine metabolism; Lesch-Nyhan syndrome (A) is a complete deficiency in hypoxantine-guanine phosphoribosyl transferase which normally reduces urate production through recycling of metabolic intermediates. It leads to hyperuricaemia and severe mental and physical disorders.

Any conditions that increase cell turnover will also predispose to hyperuricaemia; e.g. psoriasis (B), haemolytic anaemias, malignancy and cytotoxic drugs. Certain drugs also affect the way that uric acid is handled; thiazide diuretics and aspirin (C) both inhibit secretion into the renal tubules and so impair excretion. Alcohol (E) interferes with ADP/ATP metabolism and predisposes to hyperuricaemia.

Xanthine oxidase (D) is an enzyme which converts xanthine to urate. It is the target for allopurinol, which inhibits the enzyme’s function in order to lower urate levels. A deficiency in this enzyme would actually be protective for developing gout.

Question 27

A 56-year-old man is admitted with pyrexia and an acutely painful knee. On
examination, the patient is holding the joint rigidly still and is extremely reluctant to let you manipulate the joint. The knee is obviously effused and erythematous. Joint aspirate is strongly positive for white cells (75 000/mm3) with polymorphs accounting for 90 per cent of these. Blood tests show a raised urate level. The diagnosis is:
A. Osteomyelitis
B. Septic arthritis
C. Gout
D. Pseudogout
E. Monoarticular acute rheumatoid arthritis

Answer 27

B. Septic arthritis

The description in this scenario of an acutely painful limb with severe restriction of movement could be the case for any of the options here, erythema and effusion does not deliniete the options either.

Osteomyelitis (A) is rare outside of childhod, in adults it is usually associated with IV drug use, endocarditis, diaetes, or systemic sepsis. Osteomyelitis may also complicate severly debilitated patients in settings such as ITU. The high white cell count which is predominantly neutrophils is highly suggestive of an infective process. Although white cell counts in crystaline or inflammatory arthropathy (C)(D)(E) are high, they tend to be up to 50,000/mm3 and the 90% neutrophils seen here is typical of an infective process.

The high serum urate level should not be mistaken as an indication of gout, asymptomatic hyperuricaemia is 10 times more cmmon than gout, and acute gout attacks may have normal urate levels. For this reason urate levels are not used diagnostically for gout.

Question 28

A patient presents to the outpatients department following a car accident in which she has hurt her neck. Since then she has noticed some numbness in her right shoulder and neck pain. On examination you note weakness in shoulder abduction, elbow flexion, absent biceps reflex, and paraesthesia effecting the badge area over her right shoulder. The likely diagnosis is:
A. Spinal cord compression
B. Radiculopathy
C. Musculocutaneous nerve injury
D. Axillary nerve injury
E. Brown–Séquard syndrome

Answer 28

B. Radiculopathy

The patient has presented with a lower motor neurone lesion that does not extend below the level of C5, this excludes any spinal cord pathology such as compression (A) or Brown-Sequard (E).

Deltoid weakness and loss of sensation over the regimental badge area is a classic presentation of axillary nerve injury (D), this is commonly seen after shoulder dislocation or proximal humerus fractures. However, the patient in this case also has weakness of the biceps and an absent bicep reflex, which indicates a lesion of the musculocutaneous nerve (C). The unifying disgnosis here is that this is in fact a case of damage to the C5 nerve root, a radiculopathy (B).

Compression of nerve roots is a common presenting complaint and will result in LMN signs and loss of sensation at the levels affected. It is most commonly seen in the lumbar spine and cervical spine. The two most common mechanisms are disc prolapse and narrowing of the intervertebral foramina, due to conditions such as OA, Paget’s or other dengenerative conditions.

Question 29

A patient is admitted from the emergency department with new and sudden-onset urinary incontinence. The patient has previously been seen in the back pain clinic by the orthopaedic team. On examination you note a large palpable bladder. Neurological examination reveals weakness of knee flexion on the right, plantar flexion on the left and reduced ankle jerks bilaterally. Plantars are down-going on both sides. You also note patchy mixed sensory loss bilaterally. The diagnosis is:
A. Cauda equina syndrome
B. L3 radiculopathy
C. Conus medullaris
D. S1 level cord compression
E. Anterior cord syndrome

Answer 29

A. Cauda equina syndrome

The spinal cord in adults terminates at L1-2, so S1 cord compression (D) is a misnomer. The signs here are also pure LMN so this cannot be an anterior cord syndrome (E).

Conus syndrome (C) ocurs when the tail end of the cord and the nerve roots surrounding it become compressed by a lesion, typically at the L1-2 level. THis results in LMN signs below the level of the lesion and UMN at the level of the lesion. There will be mixed modality patchy sensory loss, with patchy LMN signs, along with spasticity of the anal and urinary sphincters. The lack of UMN signs here make this unlikely.

Cauda equina syndrome (A) occurs when there is compression in the spinal canal, below the level of the cord. It is a syndrome of pure LMN signs as the spinal cord is not involved. The patient will have patchy sensory and motor losses with a large degree of variability. Loss or urinary continence and anal tone are relatively consistent. It can be differentiated from a nerve root compression (B) as the deficit involves multiple levels and is bilateral (unless the nerve root compression was bilateral and acros several levels).

Question 30

A patient is being investigated for sciatica. On detailed neurological examination you elicit the following signs: sensory loss over the outer calf and dorsum of foot, weakness in dorsiflexion of toes, normal ankle reflexes, normal knee reflexes, painful straight leg raise, normal femoral nerve stretch test. At which level is the disc protrusion?
A. L2/3
B. L3/4
C. L4/5
D. L5/S1
E. S1/S2

Answer 30

C. L4/5

The sensory loss over the outer calf and dorsum of the foot points squarely at an L5 nerve root pathology. This is backed by the weaknes in dorsiflexion of the foot, with ankle (S1/2) and knee (L3/4) sparing.

It is important to remember that a disc protrusion affects the nerve root BELOW the prolapse, for this reason the answer here is (C) and not (D).