Knee Soft Tissue Injuries

Question 1

What is the main function of the medial cruciate ligament?

Answer 1

Resists valgus stress

Question 2

What is the main function of the lateral cruciate ligament?

Answer 2

Resists varus stress

Question 3

What is the main function of the ACL?

Answer 3

resists the tibia slipping anteriorly on the femur and internal rotation

Question 4

What is the main function of the PCL?

Answer 4

resists the tibia slipping posteriorly on the femur

Question 5

What is a grade 1 ligament injury?

Answer 5

Sprain - some fibres are torn but macroscopic structures are intact

Question 6

What is a grade 2 ligament injury?

Answer 6

Partial tear

Question 7

What is a grade 3 ligament injury?

Answer 7

complete tear

Question 8

Which structures make up the extensor mechanism?

Answer 8

Quadriceps muscles 
Quadriceps tendon
Patella 
Patellar tendon
Tibial tuberosity

Question 9

What are some risk factors for an injury to the extensor mechanism of the knee?

Answer 9

Previous tendonitis 
Steroids 
RA
Chronic renal failure 
Diabetes 
Ciprofloxacin & other quinolone antibiotics - cause tendonitis

Question 10

Describe the mechanism of injury in a extensor mechanism injury?

Answer 10

fall onto flexed knee with quads contraction, flexed knee and lifting heavy weight - basically anything that puts strain on the extensor mechanism

Question 11

what is a palpable gap around the front of the knee and unable to resist pressure when lifting an extended leg signs of?

Answer 11

Extensor mechanism injury

Question 12

What will confirm diagnosis of extensor mechanism injury?

Answer 12

ultrasound scan

Question 13

management of extensor mechanism injury?

Answer 13

surgical repair

Question 14

which of the two menisci is more likely to get injured?

Answer 14

Medial menisci

Question 15

What is locking of the knee and pain localised to the joint line signs of?

Answer 15

Meniscal tear

Question 16

Why can you get locking of the knee in meniscal tears?

Answer 16

ripped bit of the menisci flips on itself and prevents the knee from extending fully - usually in bucket handle tears

Question 17

What type of imaging is most appropriate for a menisci tear?

Answer 17

MRI

Question 18

Explain the mechanism of injury in menisci tears?

Answer 18

twisting on a loaded knee e.g. squatting, football

Question 19

Why do mensci tears have limited healing potential?

Answer 19

only the outer third has vascular supply so no point operating unless this part is affected

Question 20

what would impact to the lateral side of the knee e.g. a rugby tackle potentially cause?

Answer 20

MCL injury +/- ACL injury

Question 21

Management of MCL injuries?

Answer 21

Brace with early mobilisation
Physio
Pain can take months to settle

Question 22

What nerve is at risk in a LCL injury?

Answer 22

Common fibular nerve

Question 23

explain the mechanism of injury in an ACL rupture?

Answer 23

high rotational force - body moves laterally on a planted foot
high impact sports like football, rugby, skiing

Question 24

signs/symptoms of ACL rupture?

Answer 24

PAIN
“pop” heard/felt on injury
haemarthrosis formation within hour of injury (effusion due to blood in the joint)

Question 25

Why does haemarthrosis occur in ACL ruptures?

Answer 25

ACL has its own arterial blood supply which is disrupted

Question 26

Management of ACL rupture?

Answer 26

surgical reconstruction - tendon graft

physio after surgery

Question 27

Explain the mechanism of injury in a PCL rupture?

Answer 27

direct blow to anterior tibia/hyperextension injury e.g. motorbike accident

Question 28

Symptoms of PCL rupture?

Answer 28

Popliteal pain & bruising

Instability - hyperextension and going down stairs

Question 29

Management of PCL rupture?

Answer 29

Dont operate if rupture in isolation

Surgical reconstruction if multiple ligament injury

Question 30

Which way is the patella most likely to dislocate?

Answer 30

Laterally