The Knee

Question 1

What are the 3 compartments of the knee?

Answer 1

1. Patello-Femoral compartment
2. Medial Tibio-Femoral compartment
3. Lateral Tibio-Femoral compartment

Question 2

List 3 things which stabilise the knee joint

Answer 2

ligaments, capsule and muscles

Question 3

Using the mnemonic “SLIP”, how do we take a knee history?

Answer 3

1. Swelling
2. Locking ➞ meniscal tears, loose bodies
3. Instability (giving way) ➞ ligament problems (eg ACL tear), patellofemoral problems
4. Pain

• Site - medial/lateral/anterior/posterior
• exacerbating factors
• mechanical, rest or night pain

Question 4

Exacerbating factors such as stairs or hills are associated with what knee problems?

Answer 4

Patellofemoral disorders

Question 5

If a patient presents with knee pain, but examination and investigation are unremarkable… what MUST we consider?

Answer 5

Hip and/or spine problems!

Pain is commonly referred to the knee from the hip and/or spine

Question 6

What questions must we ask in a history of a sports injury?

Answer 6

1. Mechanism of injury

• Pivoting/non-pivoting
• Contact/Non-contact
• Direction of impact (varus/valgus/anterior etc)
• Deformation

2. Swelling immediate or delayed

• Haemarthrosis (occurs within 90 minutes)
• Effusion (occurs after 6-12 hours)

3. Able to finish the activity ?

Question 7

What are we looking for in a knee examination?

Answer 7

Question 8

What are we feeling for in a knee exam?

Answer 8

1. Temperature
2. Swelling
3. Tenderness
4. Crepitus

Question 9

Which tests would be used to assess small/moderate/large amounts of joint effusion in the knee?

Answer 9

Small - “bulge test”
Moderate - patellar tap
Large (tense) - ballotment

Question 10

What are we testing when we move the knee in an examination?

Answer 10

Question 11

List 3 special tests which can be used to assess the ACL

Answer 11

Lachman’s test (Most sensitive for ACL rupture)

Pivot Shift

Anterior drawer

Question 12

List 2 special tests which can be used to assess the PCL and explain each

Answer 12

1. Posterior sag ➞ In supine position, hip and knee are flexed to 90°. Examiner supports leg in the air.
   * Positive sign is a posterior sag of the tibia caused by gravitational pull
2. Posterior drawer ➞ same as Anterior drawer BUT tibia is pushed back

Question 13

How do we test the medial and lateral collateral ligaments?

Answer 13

Valgus stress test (MCL) and Varus stress test (LCL)

Performed at 20° flexion AND at full extension

Move the knee from side to side and assess the amount of opening (always slightly more movement laterally).

Check for an end point, there should not be over opening or pain. If there is either, it indicates CL problem

Question 14

What does this X-ray show?

Answer 14

Medial Collateral Ligament Rupture

X-ray shows huge opening of medial side of joint

Question 15

What “One Special Test” is used to test each ligament of the knee?

Answer 15

ACL – Lachman @ 20^o

PCL – (Sag) + Posterior Draw @ 90^o

MCL – Valgus @ 20^o

LCL – Varus @ 20^o

Question 16

What 2 tests are used to assess for a medial or lateral meniscal tear?

Answer 16

1. McMurray’s test
2. Appley’s ➞ Grinding and distraction tests

If pain is ellicited in either test it indiactes tear

Question 17

What 2 tests can be used to assess the Patellofemoral Joint?

Answer 17

1. Patellar glide test (Sage sign)

• Knee at 30^o flexion
• Translate patella medially and laterally

2. Patellar apprehension test

• Push patella laterally with the knee at 30^o flexion
• If positive patient will react with apprehension or try to push examiner away

Question 18

List 4 investigations we can do for knee pathologies and when each is indicated

Answer 18

1. X-ray ➞ fracture, arthritis
2. MRI Scan ➞ meniscal tear, ACL and CL ruptures
3. Aspiration (culture and cytology) ➞ gout, pseudogout
4. Blood tests ➞ rhumatological fators

Question 19

What does the X-ray below show?

Explain this pathology

Answer 19

Pseudogout (Chondrocalcinosis)

Calcium pyrophosphate deposition on soft tissue, here it is on both the medial and lateral meniscus

Question 20

What is Osteochondritis Dessicans (OCD)

Answer 20

Occurs when a small segment of bone begins to separate from its surrounding region due to a lack of blood supply

As a result the small piece of bone, and the cartilage covering it begin to crack and loosen

Question 21

What structure and age group is most commonly affected by Osteochondritis dissecans?

Answer 21

Usually afftects the medial femoral condyle of the distil femur and occurs in children

Question 22

What is the treatment for Osteochondritis Dessicans?

Answer 22

Conservative ➞ rest, NSAIDs, Intra-articular steroid, splint/orthotics, physiotherapy, modification of activity, weight loss

Operative ➞ arthroscopic/open, excision/repair of meniscus, removal of loose body, ligament reconstruction, patella realignment, osteotomy, joint replacement (partial/total)

Question 23

Give 5 features of patient history/presentation which may indicate ACL rupture

Answer 23

1. Severe pain
2. Immediate swelling (within 1 hour)
3. Says they did not finish the game
4. Sudden ‘popping’ sound on injury
5. Tenderness is uncommon

Question 24

In a suspected ACL rupture, what does a history of immediate swelling tell us and why?

Answer 24

Haemarthrosis (80% assoc ACL rupture) as the ligament is highly vascular, hence rupture results in a haemarthrosis

Question 25

What are the 2 ways in which ACL ruptures usually occur and which is the most common?

Answer 25

1. Pivot, non contact ➞ abrupt stopping or changing of direction (most common) 2. contact-related ➞ knee forced into hyperextension

Question 26

In an ACL rupture, usual presentation may be delayed. What else may the patient experience meanwhile?

Answer 26

Instability may be evident, in which the patient describes the leg ‘giving way’ recurrently

Question 27

ACL ruptures are often associated with what?

Answer 27

Meniscal damage

Question 28

Give 5 features of patient history/presentation which indicate a Meniscal Tear?

Answer 28

1. ‘tearing’ sensation in their knee 2. Intense sudden-onset pain, rarely finished game 3. delayed swelling (4-6 hours) 4. knee may be locked in flexion 5. Joint line tenderness (good predictor of meniscal tear)

Question 29

What is the recovery of a meniscal tear? What may be an indication for surgery?

Answer 29

Most small tears will initially swell but the pain will subside over the next few days as the tear heals. Larger tears or those who experience recurrent locking or persistant pain may require surgery (arthroscopy)

Question 30

How do meniscal tears usually occur?

Answer 30

Activities that cause direct contact or pressure from a forced twist or rotation ➞ sudden pivot or turn, deep squatting, heavy lifting Can also be caused by degerative diseases

Question 31

Which meniscus is more prone to tearing and why?

Answer 31

The medial meniscus as it is tethered to the MCL and joint capsule medially. The lateral meniscus is much more free

Question 32

What knee conditions/pathologies are associated with the following: * children * sports injurys * seniors

Answer 32

Question 33

What is shown on the X-ray below? Explain this pathology

Answer 33

Severe osteoarthritis affecting the medial compartment of the right knee (osteophytes, slerosis, cysts, loss of joint space) Moderate osteoarthritis affecting the medial compartment of the left knee

Question 34

How do we assess which treatment is needed for knee osteoarthritis

Answer 34

History and evaluation of the following: * mechanical, rest and/or night pain? * walking distance? * analgesia requirements? * response to conservative measures? * associated medical conditions?

Question 35

If all conservative measures for knee osteoarthritis fail, what is our surgical option?

Answer 35

Total Knee Replacement