Cortex - Adult orthopaedics pelvis and lower limb 2 (soft tissue injuries to the knee)

Question 1

Describe the classic presentation of a meniscal injury

Answer 1

• Classically occur with a twisting force on a loaded knee (eg turning at football, squatting).
• The patient localizes pain to the medial (majority) or lateral joint line (positive Steinmann’s test)
• An effusion develops by the following day
• Usually has mechanical symptoms – either a catching sensation or “locking” where they have difficulty straightening the knee with a 15° or so block to full extension.
• May also feel like knee about to give way if piece of meniscus is loose in the knee

Question 2

Describe the different between true knee locking and pesudo-locking

Answer 2

• True knee locking - defined as a mechanical 10-15 degrees block to full extension it is caused by a bucket handle meniscal tear, the torn inner portion of the meniscus becomes displaced into the notch and front of the knee. This produces a spongy block to full extension. - associated with meniscal tears
• Pesudo-locking - patients will often report ‘jamming’ of the knee joint; when the joint becomes temporarily stuck in a certain position and the patient has to perform a trick manoeuvre to free it. This is often associated with arthritis, specifically with a loose body becoming stuck awkwardly in the joint line.

Question 3

Describe the classic presentation of ACL ruptures

Answer 3

• Usually occur due to high rotational force
• Turning the upper body laterally on a planted foot (leading to internal rotation force on the tibia), often at football, rugby, skiing or another high impact sport.
• A “pop” is usually felt or heard
• Patient usually develops haemarthrosis (effusion due to bleeding into the joint) within an hour after injury
• Chronically, the patient may then complain of rotatory instability with their knee giving way when turning on a planted foot

Question 4

Describe how valgus stress injuries which will usually tear the MCL and potentially damage the ACL occur

Answer 4

e.g. from a rugby tackle from the side (force coming from lateral to medial putting strain on the medial aspect of the knee)

Question 5

A direct blow to the anterior tibia with the knee flexed (e.g. in a motorcycle accident) or hyperextension injury may injur what ligament ?

Answer 5

The PCL - can get a

Question 6

What structures may be damaged in a varus stress injury ?

Answer 6

The LCL with or without damage to the PCL

Question 7

What is the best investigation to do when suspecting damage to soft tissues in the knee ?

Answer 7

MRI

Question 8

What makes degenerate meniscal tears different from other tears ?

Answer 8

• Can occur as the meniscus weakens with age. The meniscus can tear spontaneously or with a seemingly innocuous injury.
• Steinmann’s test will be negative

Question 9

What clinical sign suggests a bucket handle tear ?

Answer 9

Basically results in locking of the knee

Question 10

Why does the menicus have limited healing ?

Answer 10

Because only the outer 1/3rd of the meniscus has a blood supply

Question 11

Describe the treatment of meniscal tears

Answer 11

• Often meniscal tears settle down with time and don’t need surgery
• Only relatively fresh longitudinal tears involving the outer 1/3rd are suitable
• If pain does not settle within around 3 months then arthroscopic partial menisectomy is done to remove the fragments causing the pain

Question 12

What is the principle complaint after having an ACL rupture ?

Answer 12

Rotatory instability with giving way on turning

Question 13

What are the tests and results which suggest ACL rupture ?

Answer 13

Excessive anterior translation of the tibia on the anterior drawer test and Lachman test

Question 14

What is the rule of 1/3rds regarding ACL reuptures ?

Answer 14

• Approximately 1/3 of patients will compensate well and do whatever they please (including sports)
• 1/3 will manage by avoiding certain movements but may not be able to do high impact sports
• And 1/3 will do poorly with frequent giving way even with normal daily activities.

Question 15

Describe the treatment options following an ACL rupture

Answer 15

40% of patients with ACL rupture end up having a reconstruction.

Professional sportsmen or women who need to get back to their profession as quick as possible usually proceed straight to ACL reconstruction and those whose knees give way on sedentary activity or those who have a strong desire to get back to high impact sport but cannot do so despite physiotherapy are good candidates for ACL reconstruction.

Question 16

Describe what ACL reconstruction involves

Answer 16

Involves tendon graft (usually patellar tendon or semitendinosis & gracilis autograft) being passed through tibial and femoral tunnels at the usual location of the ACL

Then requires intense physio - taking roughly a year to get back to impact sports

Question 17

Are PCL injuries common ?

Answer 17

No - usually occur with injury to the

Question 18

What is the treatment of MCL injuries and why is it different from other ligament injuries in the knee ?

Answer 18

• Due to having a good blood supply, most partial or complete tears of the MCL are expected to heal
• Acute tears are usually treated in a hinged knee brace
• Chronic MCL instability can be treated with MCL tightening (advancement) orreconstruction with tendon graft

Question 19

What are both PCL and LCL injuries often a part of ?

Answer 19

They are often part of mutli-ligarment injuries

Question 20

What is the treatment of LCL ruptures ?

Answer 20

Early repair or late reconstruction with tendon graft

Question 21

Why are complete knee dislocations (don’t mix this up with a patellar dislocation) so bad ?

Answer 21

They result in rupture of all four of the knee ligaments and have a high incidence of neurovascularinjury.

Question 22

What is the treatment of complete knee dislocations ?

Answer 22

They should be reduced as an emergency and may require external fixation for temporary stabilization and vascular assessment of the distal circulation should take place

Patients usually require multiple-ligament reconstruction.

Question 23

What are the clinical features suggestive of a PCL tear ?

Answer 23

May (usually okay, think of luke) have recurrent instability with frequent hyperextension or feeling unstable descending stairs (with anterior subluxation of the femur)

Question 24

What are the clinical features of an MCL injury?

Answer 24

Patients may have laxity and pain on valgus stress with tenderness over the origin or insertion of the MCL.

Question 25

What are the clinical features of LCL injuries ?

Answer 25

• Patients usually have marked instability on rotational movement (excessive external rotation of the tibia and varus).
• The hyperextension and varus giving rise to the injury also gives a high incidence of common peroneal nerve injury from excessive stretch.
• LCL injuries are often part of multiple ligament knee injuries with a high incidence of vascular injury (popliteal artery intimal or complete tear).