SBA Orthopaedics at A Glance
SBA Orthopaedics at A Glance
SBA Orthopaedics at A Glance
5. Osteoblasts:
A. Produce acid to resorb bone.
B. Are dormant cells trapped within the layers of lamellar bone.
C. Are bone-forming cells.
D. Are found within the synovium of joints.
Well done, you have selected the right answer.
The correct answer is C. Osteoclasts resorb bone; osteocytes are dormant
osteoblasts trapped within the bone matrix; osteoblasts are not found within
synovium.
7. Articular cartilage:
A. Is a poorly structured substance.
B. Has eight distinct zones.
C. Is very good at resisting shear.
D. Generates high levels of friction to stabilise the joint.
E. Has an extremely good blood supply.
Sorry, you have selected the wrong answer.
The correct answer is C. Articular cartilage is highly structured and can be
divided into four distinct zones. This specialised structure resists shear at the
surface, and compression at the base. It functions to reduce friction between joint
surfaces, assist in producing lubricating fluid and distribute load evenly across the
joint surface. It is aneural, avascular and alymphatic, deriving its nutrition via
diffusion from the synovial fluid.
9. Which of the following statements is true regarding the menisci of the knee?
A. A normal knee has one horseshoe-shaped meniscus.
B. Menisci are composed of elastic cartilage.
C. Menisci help with distribution of load across the knee.
D. The meniscus has a good blood supply and tears therefore often
heal effectively.
E. The medial meniscus is generally much larger than the lateral
meniscus.
Well done, you have selected the right answer.
The correct answer is C. The normal knee has two menisci, lateral and medial.
They are made of fibrocartilage arranged in longitudinal and radial bands. They
serve to: evenly distribute load across the knee joint, especially in flexion; absorb
shock; aid in stabilising the knee, especially if the anterior cruciate ligament
(ACL) is injured. They also contribute to proprioception. In adults, only the
peripheral 1/3 of the meniscus has a blood supply. Tears in this region may be
amenable to repair and may heal, but the majority of tears are in the avascular
region so will not heal. The lateral meniscus is larger and more mobile than the
smaller relatively fixed medial meniscus.
18. An octogenarian suffers a vertebral wedge fracture when sitting down heavily.
She subsequently has a DEXA scan to evaluate for the presence of osteoporosis.
According to the WHO, what defines severe osteoporosis?
A. T-score >0.5
B. T-score −0.5 to −1.5
C. Z-score >0.5
D. T-score −2.5
E. Z-score −2.5
Sorry, you have selected the wrong answer.
The correct answer is D. The DEXA scan produces two numbers. The Z-score
compares the patient to an age- and sex-matched peer and is not used in the
definition of osteoporosis. The T-score compares the patient's bone density to her
expected peak bone density (T-score = bone density aged twenty). The WHO
has defined severe osteoporosis as a T-score −2.5.
29. Rheumatoid factor:
A. Is present in 100% cases of rheumatoid arthritis (RA).
B. Is an IgF autoantibody.
C. Is present in 2% of the normal population.
D. May be transmitted between individuals via the haematogenous
route.
Well done, you have selected the right answer.
The correct answer is C. Present in 80% of people with RA and 2% of the normal
population, RhF is an IgM to IgG antibody. It is not contagious.
31. Rheumatoid arthritis:
A. Is more common in men.
B. Affects 12% of the population.
C. Is a B-cell-driven autoimmune condition.
D. Is associated with major histocompatibility complex antigen
HLA-DR4.
Well done, you have selected the right answer.
The correct answer is D. RA is more than twice as common in women and affects
1% of the population. It is driven by T-cells. It has a strong genetic component
and is associated with HLA-DR4.
37. X-rays are:
A. Generated by a stream of photons striking a charged metal
plate.
B. Part of the electromagnetic spectrum between infrared and UV.
C. Incapable of passing through tissue.
D. Ionising radiation and may damage DNA.
E. Used during a radiolabelled bone scan.
Sorry, you have selected the wrong answer.
The correct answer is D. X-rays lie between UV and gamma on the EM spectrum
and are generated by electrons striking a positively charged metal plate. They
pass through tissues, but are absorbed or attenuated to different extents,
depending on the radiodensity of the tissue. DNA may be damaged resulting in
mutations. A radiolabelled bone scan uses a gamma-emitting isotope, not X-rays.
42. Ultrasound:
A. Detects echoes of sound waves from boundaries between tissues
of different density.
B. Is easy to use and interpret.
C. Is contraindicated in patients with pneumothorax.
D. Should be avoided in children due to risk of malignancy.
Well done, you have selected the right answer.
The correct answer is A. Ultrasonic waves bounce off the boundaries between
different tissues. The images are hard to obtain and interpret and the process is
very operator dependent. Pneumothorax is not a contraindication (in fact,
ultrasound is extremely good at detecting pneumothoraces). There is no risk of
malignancy as there is with ionising radiation.
43. On a T1-weighted MRI, which of the following tissues are bright (high signal)?
A. CSF
B. Pleural effusion
C. Fat
D. Blood
E. Oedema
Sorry, you have selected the wrong answer.
The correct answer is C. T1 shows fat as white, water as dark.
46. A 15-year-old boy presents with a swollen, painful knee and fever. He has no
history of trauma but is unable to weightbear and is unwilling to move the knee.
Inflammatory markers and white cell count are raised and the knee is red,
swollen and held in 15° flexion. Passive movement exacerbates pain. The
optimal first-line treatment is:
A. NSAIDs
B. Above-knee backslab.
C. Immediate aspiration in theatre
D. Immediately start IV amoxicillin
E. MRI scan of the knee
Sorry, you have selected the wrong answer.
The correct answer is C. The history and examination findings are extremely
suggestive of septic arthritis. This is an emergency. Although antibiotics are
indicated, the optimal treatment is an initial aspiration and proceed to washout of
the joint. Antibiotics should be withheld if there is no delay in getting the child to
theatre so that culture results are not misleading. If there is a delay, antibiotics
are indicated before the joint is aspirated, but the first line should
cover Staphylococcus aureus (usually high-dose flucloxacillin or co-amoxiclav,
depending on local policy).
49. Necrotising fasciitis:
A. Is usually caused by a single organism within soft tissues.
B. Is rarely seen in diabetics.
C. Results in rapid septic shock, haemodynamic instability and
sometimes death due to toxin production.
D. Always presents with impressive skin changes and large
abscesses.
E. Is best treated without surgery.
Well done, you have selected the right answer.
The correct answer is C. Necrotising fasciitis is a rare but catastrophic infection,
usually due to multiple organisms that spread within tissue planes. It is
commoner in the immunocompromised and diabetics. Septic shock may be
severe and overwhelming but the local skin signs are often subtle and
unimpressive. Radical debridement surgery and high-dose antibiotics are
indicated.
50. Osteomyelitis in children:
A. Is commonest in the metaphysis of the bone.
B. Is always associated with penetrating trauma.
C. Should always be treated with surgery.
D. Usually produces very striking X-ray changes within the first
few days.
E. Never results in septic arthritis.
Well done, you have selected the right answer.
The correct answer is A. Osteomyelitis in children is usually due to
haematogenous spread of organisms, which become lodged in the bone where
blood flow is slowest – in the metaphysis. Penetrating trauma is a rare cause in
children. Surgery is only indicated if an abscess forms, there is a large focus of
necrotic bone or septic arthritis occurs. X-ray findings are usually subtle and take
several weeks to appear. Septic arthritis may occur if the affected physis is intra-
articular, such as the shoulder, wrist, hip or ankle.
53. Discitis:
A. Should be treated with a short course of oral antibiotics.
B. May require laminectomy and decompression.
C. Is a very rare cause of back pain in the elderly.
E. Is easily treated with antibiotics due to the excellent blood
supply of the disc allowing rapid antibiotic delivery.
E. Is a common complication of lumbar puncture.
Well done, you have selected the right answer.
The correct answer is B. Discitis is a cause of chronic back pain in the elderly and
immunosuppressed and is often misdiagnosed and under-recognised. Surgery in
the form of decompression may be required if an abscess forms. The poor blood
supply to the disc means that antibiotic delivery is difficult and prolonged courses
are required. Lumbar puncture is unlikely to cause discitis as the disc is anterior –
meningitis is more likely.
60. Supraspinatus:
A. Inserts into the lesser tuberosity of the humerus.
B. Adducts the arm.
C. Internally rotates the arm.
D. Is innervated by the suprascapular nerve.
E. Lies in the infraspinous fossa of the scapula.
Well done, you have selected the right answer.
The correct answer is D. Supraspinatus is innervated by the suprascapular nerve,
inserts into the greater tuberosity, abducts the arm and lies in the supraspinous
fossa. It forms part of the rotator cuff.
62. What is the main action on the hip of gluteus medius and gluteus minimus?
A. Adduction
B. Abduction
C. External rotation
D. Internal rotation
E. Flexion
Sorry, you have selected the wrong answer.
The correct answer is B. The abductor muscles (gluteus medius and gluteus
minimus) are important because they insert into the greater trochanter and act to
abduct the hip. They can be damaged following fracture or during surgery.
Incompetent abductors lead to a Trendelenberg gait.
67. A medical student falls whilst skiing and his bindings fail to release. He feels a
sudden pop in his left knee and is unable to continue. Within an hour there is
large amount of swelling. On returning to the UK, examination reveals a positive
anterior drawer test. The knee is stable to varus and valgus stress. X-rays are
normal. The most likely injury is:
A. Posterior cruciate ligament injury
B. Anterior cruciate ligament injury
C. Tibial plateau fracture
D. Lateral collateral ligament injury
E. Medial collateral ligament injury
Well done, you have selected the right answer.
The correct answer is B. The anterior drawer test detects excessive anterior
translation of the tibia in relation to the femur. It is a common skiing injury.
68. A rugby player is tackled hard from the left side. His opponent strikes the
lateral side of his left knee, whilst his boots remain planted in the ground. He
feels a sudden pain in the knee, which buckles beneath him. He is able to
continue the game, but the knee is painful. There is minimal swelling.
Examination reveals pain and laxity on valgus stress. Anterior and posterior
drawer tests are negative. The most likely diagnosis is:
A. Isolated posterior cruciate ligament injury
B. Isolated anterior cruciate ligament injury
C. Tibial plateau fracture
D. Lateral collateral ligament injury
E. Medial collateral ligament injury
Sorry, you have selected the wrong answer.
The correct answer is D. The lateral impact forced the knee into valgus and
sprained the lateral collateral ligament (LCL). Although sometimes associated
with an anterior cruciate ligament (ACL) injury as well, that is not the case here –
the giveaway is that the knee did not swell and the anterior drawer test is
negative.
72. Which muscle inserts into the base of the fifth metatarsal, may be avulsed in
an inversion injury (known as a Jones' fracture), and is a powerful everter of the
ankle?
A. Peroneus longus
B. Peroneus brevis
C. Peroneus tertius
D. Tibialis posterior
E. Tibialis anterior
Sorry, you have selected the wrong answer.
The correct answer is B. The tendon runs behind the lateral malleolus and inserts
into the base of the fifth metatarsal.
74. In the spinal cord, the spinothalamic tract is composed of nerves that
conduct:
A. Motor power to the lower limbs
B. Vibration sense
C. Proprioception
D. Pain, temperature and light touch
E. Sympathetic drive
Well done, you have selected the right answer.
The correct answer is D. Dorsal columns conduct vibration and proprioception.
Corticospinal tracts conduct motor signals.
77. When examining the rotator cuff, one test is to assess resisted internal
rotation by asking the patient to press their hand into their abdomen against your
resistance. This is known as the belly press test. The muscle being tested is:
A. Supraspinatus
B. Infraspinatus
C. Subscapularis
D. Teres minor
E. Biceps
Well done, you have selected the right answer.
The correct answer is C. This muscle internally rotates the shoulder.
Supraspinatus abducts, infraspinatus and teres minor externally rotate. Biceps is
not part of the rotator cuff.
78. Finkelstein's test consists of tucking the patient's thumb into their clenched fist
and ulnar deviating the wrist. It is used to test for:
A. Carpal tunnel syndrome
B. de Quervain's tenosynovotis
C. Dupuytren's contracture
D. Tennis elbow
E. Golfer's elbow
Well done, you have selected the right answer.
The correct answer is B. de Quervain's tenosynovitis is inflammation in the first
extensor compartment of the wrist.