Meniscus injuries

Question 1

What is the function of the menisci?

Answer 1

Fibro-cartilagenous ‘shock-absorbers’

They attach firmly to either end of the tibial eminence

There is a loose attachment to the capsule around their peripheries where vessels enter the meniscus

Question 2

What is the shape of the menisci?

Answer 2

Medial = circular

Lateral = C-shaped

Question 3

Which meniscus is more likely to be torn?

Answer 3

Medial meniscis - it is more fixed and twice as likely to be torn

Question 4

What is a discoid meniscus and how does it present?

Answer 4

Discoid meniscus = when in embryonic life the meniscus does not split into two and instead remains as one disc

• Presents in childhood or early adulthood when there is ‘clunking’ as the joint moves.
• It is more liable to tear than a normal meniscus.
• Asymptomatic in some.

Question 5

What are the features of a meniscal tear?

Answer 5

• Pain
• Locked knee i.e. extension not possible
• May unlock suddenly
• Swelling over 6-12hrs
• Haemarthrosis may cause early swelling - due to cruciate or synovial tear

After 12-14days:

• Appears to be back to normal
• Symptoms recur during activity e.g. football
  
  • Intermittent locking
  • Knee ‘gives way’ due to reflex quadriceps inhibition
• Episodes of pain and swelling

Question 6

What position may also predispose to meniscal tears?

Answer 6

Crouching for a long time

Question 7

What are the signs of acute/chronic meniscal tear on examination?

Answer 7

Acute:

• Swelling
• Tenderness over meniscus
• Muscle spasm
• Loss of full extension

Chronic:

• Wasting of the quadriceps
• Moderate effusioon
• Tenderness
• Less tolerance of a locked knee for long

Question 8

What is the most common type of meniscal tear?

Answer 8

‘Bucket handle’ fragment - longitudinal tear along the cartilage

Question 9

What is a ‘parrot beak’ fracture of the meniscus?

Answer 9

Horizontal cleavage tear which produces a flap which catches between the condyles

Question 10

What investigations are used to diagnose meniscal tears?

Answer 10

MRI scan or arthroscopy

Question 11

What is a complication of meniscectomy?

Answer 11

Osteoarthritis

Question 12

What is the management of torn meniscus?

Answer 12

Meniscectomy - preserve as much of the meniscus as possible to reduce risk of osteoarthritis

Question 13

What is the management of meniscal cysts?

Answer 13

Removal of the meniscus is more likely to produce a lasting cure than simple removal of the cyst

Question 14

What is the cause of meniscal cysts?

Answer 14

Degeneration causing risk of meniscal tears and tension in certain positions of flexion of the knee