KNEE DISORDERS Flashcards

1
Q

What are femoral shaft fractures

A

In healthy children and young adults usually due to high velocity trauma e.g. falls from height or road traffic collisions.

In elderly with osteoporotic bone they can occur from low velocity injury e.g. falling from standing position

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2
Q

what should be considered in injury in young children

A

consider child abuse (non accidental injury)

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3
Q

Describe appearance of proximal fragment in femoral shaft fractures

A

proximal fragment is often abducted (due to pull of glut med and min on the greater trochanter)

also flexed due to the action of iliopsoas on the lesser trochanter.

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4
Q

Describe appearance of distal fragment in femoral shaft fractures

A

Distal segment is adducted into a varus deformity due to action of adductor muscles.

Extended due to the pull of gastronemius on the posterior femur

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5
Q

What are the signs of a femoral shaft fracture

A

-The patient will have a tense swollen thigh
-Blood loss in closed femoral fracture (1-1.5l) and the patient may develop hypovolaemic shock.

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6
Q

Are there neurovascular complications in femoral shaft fractures

A
  • complications due to involvement of neighbouring neurovascular structures within the fracture site are rare.
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7
Q

How are femoral shaft fractures treated

A

treated with surgical fixation

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8
Q

How do distal femoral fractures occur in younger patients?

A

-usual mechanism is a high energy sporting injury and there is often significant displacement of fracture fragments.

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9
Q

How do distal femoral fractures occur in the elderly?

A

Usually seen in association with osteoprotic bone, mechanism is falling from standing.

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10
Q

Describe impact on the popliteal artery in distal femoral fractures

A

Popliteal artery may become involved if there is significant displacement of the fracture.

careful assessment of the neurovascular status of the limb before and after reduction of the fracture is needed

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11
Q

How do tibial plateau fractures occur?

A

Tend to be high energy injuries, mechanism is axial loading with varus or valgus angulation (an abnormal medial/laterak flexion load) of the knee.

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12
Q

What do tibial plateau fractures affect?

A

affect the articulating surface of the tibia within the knee joint.

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13
Q

Describe the types of tibial plateau fractures?

A

-They can be unicondylar (affecting one condyle) or bicondylar (affecting both tibial condyles)

-Fractures affecting the lateral tibial condyle are the most common

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14
Q

After effects of tibial plateau fractures

A

-Articular cartilage is always damaged
-Most patients will develop a degree of post traumatic OA in the affected joint
-Can be associated with meniscal tears and ACL injuries.

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15
Q

Describe Patellar fractures

A

-Accounts for 1% of all skeletal injuries
-Either caused by a direct injury e.g. knee against dashboard.
-Or caused by eccentric contraction of quadriceps
-Most occur in patients aged 20-50 years

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16
Q

Describe appearance of patellar fracture

A

-Often a palpable defect in the patella and a haemarthrosis (blood in the joint)

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17
Q

What may the patient be unable to perform in a patellar fracture

A

If the extensor mechanism is disrupted (complete split of patella to quadriceps tendon insertion)
-Patient will be unable to perform a straight leg raise.

18
Q

Treatment of patellar fracure

A

Displaced patellar fractures require reduction and surgical fixation
Undisplaced patellar fractures can be protected whilst healing takes place via splinting + crutches
(do not usually require surgical fixation)

19
Q

What is a patellla dislocation

A

Refers to the patella being completeley displcaed out of normal alignment
Partial displacement is known as subluxation

20
Q

Causes of patella dislocation

A

-Trauma, often a twisting injury in slight flexion or a direct blow to the knee
-Usual mechanism is internal roatation of the femur on a planted foot whilst flexing the knee

21
Q

Most common affected by patella dislocation

A

-Athletic teenagers
(MOI: sudden change of direction during sports)

22
Q

What factors can predispose a patella dislocation (5)

A

-Generalised ligamentous laxity
-Weakness of the Quadriceps. especially the VMO.
-Shallow trochlear groove with a flat lateral lip
-Long patellar ligament
-Previous dislocations

23
Q

Treatment of patella dislocations

A

-Treatment involves extending the knee then manually reducing the patella.
-Immobilisation is used whilst healing takes place + physiotherapy to strengthen the VMO.

24
Q

Describe meniscal injuries

A

-Meniscal injuries (meniscal tears) occur due to sudden twisting motion of a weight-bearing knee in high degree of flexion.

25
Q

How will patient present in meniscal injuries

A

-Patients describe intermittent pain, localised to the joint line alongside knee clicking, catching, locking or sensation of giving way.

26
Q

Delayed symptom of meniscal injuries

A

Swelling due to reactive effusion or not at all as the menisci are largely avascular.

27
Q

Meniscal injuries on examination

A

Joint line tenderness and restricted motion due to pain or swelling.
Mechanical block to motion or locking can occur with a displaced tear due to loose meniscal fragments becoming trapped between articular surfaces

28
Q

Treatement of meniscal injuries

A

-Acute traumatic menisclar tears are usually treated surgically either by meniscectomy or meniscal repair.

29
Q

what do collateral ligament injuries result from?

A

acute varus or valgus angulation of the knee - common in sporting injuries especially football

30
Q

which collateral ligaments of the knee are at risk in acute varus and valgus strain?

A

In acute valgus strain the medial collateral ligament (MCL)
is at risk
in Varus strain the lateral collateral ligament (LCL) is at risk.

31
Q

why does a torn LCL have a higher chance of causing knee instability?

A

The medial tibial plateau forms a deeper and more
stable socket for the femoral condyle than the lateral tibial plateau so an intact LCL plays a more critical role in maintaining stability of the knee.

32
Q

what is the ‘unhappy triad’ of knee injuries? what does it result from?

A

ACL + MCL and medial meniscus injury

result of strong force applied to lateral aspect of the knee

33
Q

how is the ACL commonly torn?

A

quick deceleration, hyperextension or rotational injury

large force to the back of the knee with the joint partially flexed

34
Q

what does the patient report in an ACL tear?

A

popping sensation

immediate swelling

instability (tibia slides anteriorly under femur)

35
Q

what is the most common mechanism of injury for PCL injury?

A

‘dashboard injury’ - the knee if flexed and a large force is applied to upper tibia, displacing it posteriorly

falling on flexed knee with ankle plantarflexed

36
Q

how can ACL and PCL injuries be detected?

A

drawer tests

lachmans for ACL

37
Q

what is required to dislocate the knee?

A

at least 3 of the 4 ligaments must be ruptured

38
Q

what associated injury is common in popliteal injuries and why?

A

arterial injury as popliteal artery is tethered proximally

as popliteal artery is immobile there is high risk of injury - essential to assess vascularity after treatment

39
Q

what are acute and delayed effusions?

A

acute < 6 hours after injury

delayed > 6 hours

40
Q

what can acute knee effusions be divided into?

A

haemoarthrosis - ACL rupture until proven otherwise

lipo-haemoarthrosis - fracture until proven otherwise

41
Q

What kinds of bursitis can occur in the knee?

A

-Prepatellar (housemaids knee)
-Infrapatellar (clergyman’s knee)
-Suprapatellar
-Semimembranous (baker’s cyst)