MSK Flashcards
(48 cards)
An 80 y/o woman is brought to A&E following a mechanical fall. She is unable to weight bear on her right leg, which is shortened and externally rotated. A hip x-ray shows a displaced R subcapital fracture. She has a background of osteoarthritis affecting her hips and knees, and advanced Parkinson’s disease which has effectively rendered her bedbound.
Which surgical option would be most appropriate?
A. A cannulated hip screw B. A total hip replacement C. A dynamic hip screw D. Intra-medullary femoral nail E. A hemiarthroplasty
E. A hemiarthroplasty
This is a displaced intracapsular fracture, so the blood supply to the femoral head has been disrupted. Left alone this will develop necrosis and so it should be replaced. The next decision is whether to replace the entire hip or just the head of the femur; this woman is bedbound and so unlikely to see benefit from a total hip replacement which is a larger operation (despite the presence of osteoarthritis in the hips which can be an indication for THR).
NB: the head is replaced in displaced intracapsular fractures because of the risk of blood supply disruption and subsequent avascular necrosis. This risk is around 30%, so a the majority of fractures could be reduced and fixed without replacement of the femoral head. Replacement is generally done in the elderly population because of the increased risk associated with multiple surgeries in this demographic. In younger patients it is desirable to preserve native bone (always better than a replacement), and they can tolerate multiple surgeries in the event that a subsequent surgery for replacement of the femoral head is necessary.
Which artery provides the main supply for the head of the femur?
The medial circumflex artery - a branch of the deep femoral artery. There is also a contribution from the lateral circumflex branch.
There is also a contribution from the foveolar artery, which runs through the ligamentum teres at the head of the femur. The contribution from this artery is significant in children, but not significant in adults.
There may also be some contribution from the inferior gluteal artery.
Briefly describe primary and secondary bone healing
Primary bone healing is carried out by osteoblasts and osteoclasts between two segments of bone directly adjaceant to each other
Secondary bone healing is far more common and involves the formation fo a soft callous which ossifies and then remodels
A 34 year old man is brought to A&E by ambulance following a car crash. The initial assessment is completed, but 1 hour later he complains of pain in his right calf. The registrar arrives 30 minutes later and by this point the patient is in severe pain. On examination the calf is very tender and tense, but not swollen and there are no signs of trauma in the painful area. The patient has reduced sensation distal to the swelling, but intact pulses.
What is the most likely cause of his pain?
A. Compartment syndrome B. Acute limb ischaemia C. Pulmonary embolism D. Rhabdomyolysis E. Deep vein thrombosis
A. Compartment syndrome
Compartment syndrome is a pressure increase within a fascial compartment, generally occurring in the limbs. This pressure increase usually occurs after high-energy trauma as a result of inflammation and bleeding. The pressure compresses (in order) veins, nerves, and the arterial supply, eventually causing ischaemic damage.
Compartment syndrome generally begins within hours of the insult, and is often described as featuring pain out of proportion to the insult. The affected compartment will not generally be swollen, as the compartment to which the swelling is confined does not distend - hence the issue.
A 60 y/o man presents to A&E after loss of consciousness and a fall. He is complaining of left knee pain, but examination of the knee revels no swelling, tenderness, or other abnormalities.
What is the most appropriate next step?
A. Examine the ankle B. Order an AP x-ray C. Order a CT scan D. Examine the hip E. Order AP and lateral x-rays
D. Examine the hip
This patient actually has a NOF#, but pain from the hip can be referred to the knee. This is why it is standard practice in orthopaedic exams to finish by examining one joint above, and one below the joint you have already examined.
What is the 1 year mortality of a treated NOF#?
~30%
Describe the Garden classification of hip fractures
Type I - Incomplete fracture
Type II - Complete fracture but non-displaced
Type III - Complete fracture, partially displaced
Type IV - Complete fracture, fully displaced
When is a reverse shoulder arthroplasty appropriate and why?
It is appropriate where there is damage to, and loss of function of, the supraspinatus. Without the supraspinatus, the arm cannot be properly adducted as the supraspinatus usually functions to anchor the head of the humerus into the glenoid fossa while the deltoid abducts the arm.
A reverse shoulder arthroplasty changes the mechanical advantage of the deltoid thereby allowing it to abduct the arm well, even without the supraspinatus anchoring the head of the humerus.
The hip capsule attaches to the acetabulum proximally, where does it attach distally?
Anteriorly - to the intertrochanteric line
Posteriorly - about 1cm above the intertrochanteric crest
What are the muscles of the rotator cuff, and what are their functions?
Infraspinatus - External rotation
Supraspinatus - First 15 degrees of abduction/ anchors the humerus against the glenoid while the deltoid abducts the arm
Subscapularis - Internal rotation
Teres minor - External rotation
A 60 y/o man presents to A&E after loss of consciousness and a fall. His hip is tender on examination with globally reduced active and passive movement, but there is no leg length discrepancy or resting rotation. AP and lateral pelvic x-rays are normal.
What is the most appropriate next step?
A. Order x-rays of the lumbar spine
B. Refer for physiotherapy and occupational therapy
C. Discharge and repeat AP and lateral x-rays in 2 weeks
D. Book a slot in theatres for a hemiarthroplasty
E. Order a CT scan
E. Order a CT scan
Non-displaced NOF# can be missed on an x-ray, so a CT scan would be indicated as this clinical picture is still most suggestive of a NOF#. The classic external rotation and limb shortening are absent, but this is because the fracture is not displaced, and does not contradict the most likely diagnosis. The diagnosis should be established before booking a theatre slot, as the exact nature of the fracture determines surgical management.
A 74 year old woman present to A&E with a swollen wrist having fallen backwards onto her hand. The wrist is painful and tender to touch, and x-ray shows a distal radial extra-articular fracture with volar displacement of the distal fragment.
Which fracture is this describing?
A. Barton's B. Smith's C. Colles' D. Hill-Sachs E. Bankart's
B. Smith’s
This is a description of a Smith’s fracture - a distal extra-articular radial fracture with volar (ventral/ towards the palm) displacement of the distal fragment.
NB: Though you should know the main eponymous fractures, it is better in an exam to describe them (e.g. say “a distal extra-articular radial fracture with volar angulation of the distal fragment” instead of “a Smith’s fracture”. This is because some of the eponymous fractures have very specific criteria (e.g. Colles’ fracture technically includes an avulsion fracture of the ulnar styloid) so it is safer and clearer to describe the fracture methodically.
What are the 4 main features of osteoarthritis on an x-ray?
The acronym to use here is ‘LOSS’:
L - Loss of joint space
O - Osteophytes (bone spurs)
S - Subchondral sclerosis (white opacities under the joint surface)
S - Subchondral cysts (circular lucencies under the joint surface)
How should you classify complications of any fracture?
They should be classified according to timing and whether they are localised or systemic;
Immediate local:
Injury to adjaceant structures (nerves, vessels, organs, muscles, tendons, ligaments)
Pain
Immediate systemic:
Blood loss +/- shock
Early local:
Operative injury to adjaceant structures if operating
Early systemic: Complications of anaesthetic if operating Pain Nausea Delirium VTE UTI Atelctasis +/- pneumonia Bed sores Fat embolism syndrome
Late local: Malunion or non-union Avascular necrosis Osteoarthritis Tendonopathy Muscle weakness Permanent deformity Surgical material infection
Late systemic:
Reduced quality of life depending on functional status
Increased morbidity with impaired function or mobility
What are the 4 classic signs of a fracture?
Pain
Swelling
Deformity
Crepitus
Which compartment of knee most often gets OA?
Medial
Treatment of OA
Analgesia
Physio
Joint injections
Sometimes joint replacement
Treatment of RA
NSAIDs for symptom control
Steroids for short-term flare control
Long-term try monotherapy with DMARDs: methotrexate, leflunomide or sulfasalazine
Consider hydroxyxholoquine in mild/ palindromic disease (where joints return to normal between flares)
Add a second DMARD if monotherapy is insufficient
Consider adding biologics (rituximab, upadacitinib)
What are the 4 main radiographic features of RA?
The acronym for rheumatoid arthritis is ‘LOSE’:
L - Loss of joint space
O - Osteoporosis in the affected joint
S - Soft tissue swelling
E - Bony erosions
A 55 year old woman presents to her GP with pain in her hands that has been gradually worsening for the past few months, and is accompanied by stiffness. O/E there is bilateral swelling of the PIP and DIP joints which is accompanied by swelling and warmth over the joints. The motion of the hands is severely limited due to the pain and stiffness. She has been previously fit and well, with no other symptoms to report. Investigations yield the following results:
ESR - 48mm/h (elevated) Rh factor positive Anti-CCP antibodies negative HLAB27 positive X-ray shows marginal bone erosions with a 'pencil in cup' appearance, soft tissue swelling, and a subluxed 4th finger DIP
What is the most likely diagnosis?
A. Reactive arthritis B. Osteoarthritis C. Rheumatoid arthritis D. Enteropathic arthritis E. Psoriatic arthritis
E. Psoriatic arthritis
This is a tough question, but helpful since distinguishing between arthritides can be very tricky.
‘A’ is unlikely to be correct for a variety of reasons: rheumatoid arthritis (RhA) rarely involves the DIP joints, the anti-CCP antibody test is negative, and the x-ray findings are not especially consistent with RhA. Admittedly the anti-CCP antibody test is not very sensitive for RhA (55-60% sensitive, 95% specific), but in conjunction with the involvement of DIP joints and the x-ray findings, this clinical picture is unlikely to be caused by RhA.
‘B’ is probably the second best answer, as it could cause this pattern of joint involvement. However the raised ESR and presence of HLAB27 is more supportive of a seronegative spondyloarthropathy (e.g. psoriatic arthritis). Rheumatoid factor is classically associated with RhA, but can be associated with a number of other conditions, as is the case here. Finger subluxation is associated with advanced joint destruction in both osteoarthritis and psoriatic arthritis.
What are the components of a DAS28 score?
ESR, tender joint count, swollen joint count, general health line (line between ‘good’ and ‘bad’ general health - essentially a score out of 10).
A DAS28 of greater than 5.1 implies active disease, less than 3.2 low disease activity, and less than 2.6 remission.
What proportion of shoulder dislocations are anterior?
95% - it is overwhelmingly the most common type
Which of the following is true regarding posterior shoulder dislocations?
A. They are significantly more common in females
B. They account for ~1/3 of shoulder dislocations
C. The lightbulb sign is apparent on AP x-ray due to fixed external rotation
D. They are classically caused by seizures
E. They can be caused by application of force to an extended, abducted, and externally rotated humerus
D. They are classically caused by seizures
Seizures and electrocution are the classic causes of a posterior shoulder dislocation, which only makes up 5% of shoulder dislocations. As with all shoulder dislocations, they are most common in men. The lightbulb sign is seen on AP x-ray but is caused by internal rotation, not external. The mode of injury described in ‘E’ is classic of an anterior dislocation.
General management of shoulder dislocation
A-E assessment if necessary Provide analgesia Examine for neurovascular compromise AP, lateral, and 'Y' view x-rays Reduce the shoulder with appropriate analgesia (Entonox) +/- sedation Re-examine neurovascular status Repeat x-ray series Place arm in sling and arrange follow-up inc. with physio if necessary
