Knee ligament injuries

Question 1

describe the function of the medial collateral ligament(MCL) and the lateral collateral ligament(LCL)

Answer 1

MCL = resists valgus stress
LCL = resists varus stress

Question 2

describe the function of the anterior cruciate ligament(ACL)

Answer 2

resists anterior subluxation of the tibia and internal rotation of the tibia in extension

Question 3

describe the function of the posterior cruciate ligament(PCL)

Answer 3

resists posterior subluxation of the tibia, ie anterior subluxation of the femur and knee hyperextension

Question 4

briefly describe how knee ligament injuries are graded

Answer 4

grade 1 = sprain
grade 2 = partial tear
grade 3 = complete tear

Question 5

describe the healing potential of the MCL

Answer 5

healing expected in majority of partial and complete tears, with little or no instability

Question 6

what may a MCL rupture lead to

Answer 6

valgus instability

Question 7

what may an ACL rupture lead to

Answer 7

rotatory instability

Question 8

what may a PCL rupture lead to

Answer 8

recurrent hyperextension or instability descending stairs

Question 9

what is involved in the treatment of acute and chronic MCL tears

Answer 9

acute = hinged knee brace
chronic = MCL tightening or reconstruction with tendon graft

Question 10

how are ACL injuries most often caused

Answer 10

by sports (common)

Question 11

what is the classic history of an ACL injury

Answer 11

“pop”, haemarthrosis and giving way on turning

Question 12

what are the different outcomes of an ACL injury

Answer 12

patient can compensate and are able to function well
patient can avoid instability by avoiding certain activities
patient do not compensate and have frequent instability

Question 13

what surgical treatment is used in ACL injury

Answer 13

ACL reconstruction, repair doesn’t work

Question 14

when is surgical treatment used in ACL injury

Answer 14

rotatory instability not responding to physio, professional athletes to speed up process, protect meniscal repair

Question 15

what effect does ACL reconstruction have on pain and arthritis

Answer 15

does not relieve pain and does not prevent arthritis

Question 16

how long is the rehab process after ACL surgery

Answer 16

3 to 12 months, 9 months before return to sport if meeting physio targets

Question 17

what type of injury does LCL injury often occur with

Answer 17

PCL or ACL injury

Question 18

describe healing of LCL injury

Answer 18

does not heal

Question 19

what treatment is used in LCL rupture

Answer 19

early repair or late reconstruction with tendon graft

Question 20

what can the hyperextension and varus seen with LCL injury cause

Answer 20

common peroneal nerve injury from excessive stretch

Question 21

what clinical features are usually seen with a LCL injury

Answer 21

marked instability on rotational movement

Question 22

in isolated PCL injury when is surgical reconstruction considered

Answer 22

in those with severe laxity, recurrent instability, frequent hyperextension or instability descending stairs

Question 23

what treatment is usually used in multi-ligament injuries and why

Answer 23

surgical reconstruction due to high instability

Question 24

what does complete knee dislocation results in in terms of the knee ligaments

Answer 24

results in rupture of all 4 ligaments

Question 25

what complications can be seen with complete knee dislocation

Answer 25

popliteal artery injury, neurovascular injury, compartment syndrome