[15] Cruciate Ligament Tears

Question 1

What is the importance of the ACL?

Answer 1

It is an important stabilising ligament of the knee joint, being the primary restraint to limit anterior translocation of the tibia (relative to the femur) and also contributing to knee rotational stability (internal)

Question 2

What is the clinical result of the importance of the ACL?

Answer 2

A tear of the ACL can result in significant functional impairment of the joint

Question 3

Who does an ACL tear typically occur in?

Answer 3

An athlete with a history of twisting the knee whilst weight-bearing

Question 4

Do ACL ligaments occur with contact?

Answer 4

The majority occur without contact

Question 5

What does an ACL tear most commonly result from?

Answer 5

Landing from a jump

Question 6

Will an athlete be able to continue to play after an ACL tear?

Answer 6

No

Question 7

How does an ACL tear typically present?

Answer 7

With a rapid joint swelling and significant pain

Question 8

What may be evident if the presentation of an ACL tear is delayed?

Answer 8

Instability, in which the patient describes the leg as ‘giving way’

Question 9

Why is there rapid joint swelling with an ACL tear?

Answer 9

Due to the ligament being highly vascular, hence the damage to the ligament results in haemarhrosis being clinically apparent within 15-30 minutes

Question 10

What specific clinical tests can identify potential ACL damage?

Answer 10

• Lachman Test
• Anterior Draw Test

Question 11

What is the more sensitive of the two tests for ACL?

Answer 11

Lachman’s test

Question 12

What does Lachman’s test involve?

Answer 12

Placing the knee in 30 degrees of flexion and, with one hand stabilising the femur, pulling the tibia forward to assess the amount of anterior movement of the tibia compared to the femur. The other knee is then examined for comparison

Question 13

What does the anterior draw test involve?

Answer 13

Flexing the knee to 90 degrees, placing the thumbs on the joint line and the index fingers on the hamstring tendons posteriorly. Force is then applied anteriorly to demonstrate any tibial excursion, which is then compared to the opposite site

Question 14

What are the differential diagnoses of an ACL tear?

Answer 14

• Fracture
• Meniscal tear
• Collateral ligament tear
• Quadriceps or patellar ligament tear
• Septic arthritic or crystal arthropathy

Question 15

What investigations are done in suspected ACL tear?

Answer 15

• X-ray of the knee (AP and lateral)
• MRI scan of knee

Question 16

What is the purpose of an x-ray of the knee in a suspected ACL tear?

Answer 16

To exclude bony injuries, any joint effusion, or a lipohaemarthrosis

Question 17

How sensitive is an MRI scan of the knee?

Answer 17

>90%

Question 18

What additional use may MRI scanning of the knee have in suspected ACL tear?

Answer 18

It may also pick up any associated menisceal tears (50% of ACL tears will also have a meniscal tear)

Question 19

Which meniscus is more commonly affected in ACL tears?

Answer 19

Lateral

Question 20

What is involved in the immediate management of a suspected ACL tear?

Answer 20

RICE (rest, ice, compression, elevation)

Question 21

What are the options for the specific treatment of an ACL rupture?

Answer 21

Either conservative or surgical

Question 22

What does the decision to manage ACL rupture conservatively or surgically depend on?

Answer 22

• The suitablity of the patient for surgery
• Their current levels of activity

Question 23

What does the conservative treatment of an ACL tear involve?

Answer 23

Rehabilitation, which utilises strength training of the quadriceps to stabilise the knee

Question 24

Is inpatient admission required for a torn ACL?

Answer 24

Rarely

Question 25

Why is inpatient admission rarely required in the emergency setting for torn ACL?

Answer 25

The patient can often fully weight bear, and a canvas knee splint can be applied for comfort

Question 26

What does a surgical repear of the ACL involve?

Answer 26

The use of a tendon or artificial graft

Question 27

What will the surgical repair of the ACL always be preceded by?

Answer 27

Prehabilitation

Question 28

What happens in prehabilitation before surgical repair of ACL tear?

Answer 28

The patient will engage with a physiotherapist for a period of months prior to the surgery

Question 29

What are the complications of ACL tear?

Answer 29

Post-traumatic osteoarthritis - well-establsihed complication of both ACL injury and ACL reconstructive surgery

Question 30

What is more common, anterior or posterior cruciate ligament tear?

Answer 30

Posterior cruciate ligament

Question 31

What does the PCL do?

Answer 31

It is the primary restraint to posteiror tibial translation, and works to prevent hyperflexion of the knee

Question 32

When do PCL tears typically occur?

Answer 32

In high energy-trauma, such as a direct blow to the proximal tibia during a RTA

Question 33

When do PCL tears less commonly occur?

Answer 33

In low-energy trauma when there is hyperflexion of the knee with a plantar-flexed foot

Question 34

What will a torn PCL present with?

Answer 34

Immediate posterior knee pain

Question 35

What will be found on examination with a torn PCL?

Answer 35

• Instability of the joint
• Positive posterior draw test (with posterior sag)

Question 36

What is the gold standard for the diagnosis of torn PCL?

Answer 36

MRI scanning

Question 37

How are PCL tears managed in the first instance?

Answer 37

Often conservatively, with a knee brace and physiotherapy

Question 38

When might a patient require surgical management of a PCL tear?

Answer 38

If they continue to be symptomatic after conservative treatment and has recurrent instability of the knee joint

Question 39

What is involved in PCL tear repair surgery?

Answer 39

The insertion of a graft