Disorders of the knee

Question 1

What is the main way a femoral shaft fracture occurs in children?

Answer 1

High velocity trauma

Question 2

What is one of the main risks of a femoral shaft fracture?

Answer 2

The patient may go into hypovolaemic shock as 1,000- 1,500 ml of blood is lost

Question 3

Where does a tibial plateau fracture occur?

Answer 3

On the articulating surface of the tibia with the knee

Question 4

What kind of tibial plateau fracture is the most common?

Answer 4

Fracture of the LATERAL tibial condyle

Question 5

What will a patient with a complete patellar fracture, distal to the insertion of the quadriceps be unable to do?

Answer 5

Unable to perform a straight leg raise

Question 6

When looking at an X-ray of a patella, why must you be careful when diagnosing a patellar fracture?

Answer 6

A bipartite patella - present in 8% of the population Can be mistaken for a patellar fracture

Question 7

What does subluxation of the patella mean?

Answer 7

A partial displacement of the patella

Question 8

What is the most common direction for the patella to displace?

Answer 8

Laterally

Question 9

How does a patella dislocation most commonly occur?

Answer 9

From a sudden change of direction playing sports

The femur internally rotates on a planted foot whilst the knee is flexed

Question 10

Name some predisposing fractures for patellar dislocation

Answer 10

• Generalised ligament laxity
• Weak quadriceps muscles (especially the VMO)
• Shallow trochlear groove with a flat lateral lip
• Long patellar ligament
• Previous dislocation

Question 11

What is the most common kind of knee injury?

Answer 11

A meniscal tear

Question 12

What kind of symptoms might a patient report if they had a meniscal injury?

Answer 12

• Intermittent pain localised to the joint line
• Knee may ‘click’, ‘latch’ or ‘lock’

Question 13

Which ligament is at risk in acute valVus strain?

Answer 13

The Medial Collateral Ligament

Question 14

Which ligament is at risk in acute vaRus strain?

Answer 14

The Lateral Collateral Ligament

Question 15

What force does the lateral collateral ligament resist?

Answer 15

Valgus force

Question 16

What force foes the medial collateral ligament resist?

Answer 16

Varus force

Question 17

Which collateral ligament is injured more commonly and why?

Answer 17

The MCL

It has a broader attachment and is attached to the collateral ligament which makes it more rigid, therefore easier to damage

Question 18

Which collateral ligament has a higher chance of causing knee instability?

Answer 18

The LCL

Question 19

What 3 things are injured in the Unhappy Triad (Blown Knee)?

Answer 19

• ACL
• MCL
• Medial Meniscus

Question 20

Describe the kind of motion that usually causes the ACL to tear

Answer 20

Sudden deceleration, hyperextension or rotational injury - not usually injured in contact sports

Question 21

What is the most common mechanism of a PCL injury?

Answer 21

Dashboard injury - flexed knee colliding with dashboard in a RTA or falling on a fixed knee in sport

Question 22

Name the 2 tests that can be used to test for ACL/ PCL injury

Answer 22

• Lachman’s test
• Draw test

Question 23

Which ligaments need to be torn for the knee to dislocate?

Answer 23

At least 3 of either:

• ACL
• PCL
• MCL
• LCL

Question 24

Which artery is commonly injured if the knee dislocates?

Answer 24

Popliteal artery

Question 25

Define 'acute' and 'delayed' knee effusions

Answer 25

**acute** = **\<6** hours after injury **delayed** = **\>6** hours after injury

Question 26

How can acute knee effusions be divided?

Answer 26

* **Haemarthrosis** - blood in the joint (diagnostically an **ACL injury** unless proven otherwise) * **Lipo-haemarthrosis** - blood and fat in the joint (diagnostically a **fracture** unless proven otherwise as fat is released from bone marrow)

Question 27

What bursae is inflamed in Housemaid's knee?

Answer 27

**Pre patellar bursa**

Question 28

What bursae is inflamed in Clergyman's knee?

Answer 28

Infrapatellar bursa

Question 29

Name some causes of Suprapatellar bursitis

Answer 29

* Osteoarthritis * RA * Infection * Gout or pseudo gout * Repetitive microtrauma (running on uneven surfaces)

Question 30

Describe how **Baker's cyst** or semimembranous bursitis occurs

Answer 30

If the **knee joint is inflamed**, **effusion** can force itself out of a small opening between the knee joint into the semimembranous bursa Causes a **swelling on the back of the knee**

Question 31

What is Osgood- Schlatter's Disease?

Answer 31

Inflammation of **site of insertion** of the **patellar ligament** into the **tibial tuberosity**

Question 32

What group of people does Osgood-Schlatter's most commonly occur in?

Answer 32

Sporty teenagers Bilateral in most cases

Question 33

What symptoms might a patient describe in Osteoarthritis of the knee?

Answer 33

* pain that comes and goes * pain precipitated by kneeling,bending, squatting etc * pain and stiffness that is worse after prolonged rest

Question 34

What is septic arthritis?

Answer 34

Invasion of the joint space by micro-organisms mainly staph. aureus

Question 35

What is the symptom triad of patients with septic arthritis?

Answer 35

* Pain * Fever * Reduced range of motion

Question 36

Why do meniscal tears heal poorly?

Answer 36

Poor blood supply

Question 37

Why may patients with a torn meniscus present with a 'locked knee'?

Answer 37

Large fragment of the meniscus can get caught in the knee mechanism of the knee