Common conditions of the knee

Question 1

Key ligaments within the knee?

Answer 1

Cruciate ligaments:

• ACL
• PCL

Collateral ligaments:

• MCL
• LCL

Question 2

What are the menisci of the knee?

Answer 2

> Specialised C-shaped cartilage:

• Triangular in cross-section
• Medial = attached to deep MCL
• Lateral

> Function:

• AID force transmission
• Increase stability

Question 3

What can cause a meniscal tear?

Answer 3

> Acute = Twisting especially in deep flexion

> Degenerative = Osteoarthritis

> Medical meniscal tears more common

Question 4

What is the significant difference between an acute and a degenerative MCL tear?

Answer 4

Degenerative is not repairable where as acute is

Question 5

How does someone present with a meniscal tear?

Answer 5

> Pain
Clicking
Locking
Intermittent swelling

Question 6

Meniscal tear examination?

Answer 6

1) Look - effusion

2) Feel:
- Tender joint line at point of tear (esp medial tear)

3) Move:
- Mechanical block to movement
- McMurrays test positive
- Fail deep squat
- Thassaly’s test positive

Question 7

Meniscal tear investigations?

Answer 7

X-ray

• Arthritis
• Fracture

MRI

• Most sensitive test
• High False positive rate

Question 8

Meniscal tear management?

Answer 8

Unlikely to heal due to poor blood supply

Non-operative

• Rest
• Nsaids
• Physiotherapy
• Hamstring and Quadriceps strengthening

Operative
- Arthroscopy = Repair or
resection

Question 9

What is osteoarthritis?

Answer 9

Degenerative change of synovial joints

Progressive loss of articular cartilage

Secondary bony changes

Question 10

Characteristic presentation of osteoarthritis?

Answer 10

Characterised by worsening pain and stiffness of the affected joint that gets worse with activity and better with rest

Question 11

Blood supply to the ACL?

Answer 11

Middle geniculate artery

Question 12

innervation of the ACL?

Answer 12

Posterior articular nerve a branch of the tibial nerve

Question 13

What is the function of the ACL?

Answer 13

Primary restraint to anterior translation of the tibia relative to femur

Secondary restraint to tibial rotation and varus/valgus stress

Question 14

How is the ACL usually torn?

Answer 14

Non-contact pivot injury

Question 15

Presentation of an ACL tear?

Answer 15

Heard a ‘pop’ or ‘crack’

Immediate swelling (70%)

haemarthrosis

Unable to continue playing

Can walk in straight line but hurts to turn

Deep pain

Question 16

Examination ACL tear?

Answer 16

1) Look = Effusion (if recent injury)
2) Feel

3) Move
- Anterior draw
- Lachmann’s test
- Pivot shift = Best done under anaesthetic

Question 17

Investigations for an ACL tear?

Answer 17

X-ray

• Segond fracture
• Avulsion # of anterolateral ligament

MRI
- ACL
- Meniscii
> Lateral – simultaneous with acl tear (48%)
> Medial – secondary to shear from chronic instability
- MCL

Question 18

ACL treatment?

Answer 18

Non-operative = Focussed quadricep programme

Operative= ACL reconstruction:
> +/- partial menisectomy +/- ligament repair or augmentation
> Hamstring graft

Question 19

What is the most common ligament injury of the knee?

Answer 19

The MCL (Medial collateral ligament?

Question 20

How does MCL tear usually occur?

Answer 20

Sever valgus stress, usually from contact

Question 21

Associated injuries with MCL tear?

Answer 21

• ACL tear

- Meniscal tear

Question 22

Presentation of a MCL tear?

Answer 22

>  Heard a ‘pop’ or ‘crack’
>  Pain ++ on Medial side
>  Unable to continue playing
>  Bruising medial knee
>  Localised swelling

Question 23

Examination of MCL tear?

Answer 23

Look

• Medial swelling
• Bruising

Feel

• Tender medial joint line
• Tender femoral insertion of mcl

Move

• Painful in full extension
• Opening on valgus stress

Question 24

Investigations for MCL tear?

Answer 24

X-ray

• May be normal
• Calcification at femoral insertion (Pellegrini-stieda), Chronic injury

MRI

• Modality of choice
• Assess location and severity of injury
• Identify other pathologies (ACL, menisci)

Question 25

Management of MCL tear?

Answer 25

Non-operative

• Majority
• Rest and NSAIDs
• Physiotherapy
• Brace for comfort

Operative

• Severe tears
• Failed non-operative management
• Repair or reconstruction
• Repair: avulsions = midsubstance tear with good tissue
• Reconstruction: damaged tissue

Question 26

What is Osteochondritis dissecans?

Answer 26

Pathological lesion affecting articular cartilage and subchondral bone

2 forms:

1) Juvenile = 10-15 years while growth plates still open
2) Adult

Question 27

Causes of osteochondritis dissecans?

Answer 27

Cause

• Hereditary
• Traumatic
• Vascular = Adult form

Question 28

Most common location of osteochondritis dissecans?

Answer 28

Knee = most common

Posterolateral aspect of medial femoral condyle (70%)

Question 29

Presentation of osteochondritis dissecans?

Answer 29

• Activity-related Pain., Poorly localised
• Recurrent effusions
• Mechanical symptoms
  > Locking
  > Block to full movement

Question 30

Examination of osteochondritis dissecans?

Answer 30

• May be normal

Look
- effusion

Feel
- Localised tenderness

Move

• stiffness
• Block to movement
• Wilson’s test

Question 31

Investigations for osteochondritis dissecans

Answer 31

X-ray
- Add in tunnel view (flexed 30-50 deg)

MRI

• Lesion size
• Status of cartilage and subchondral bone
• Signal intensity, Oedema suggests instability of fragment

Question 32

Management of osteochondritis dissecans?

Answer 32

Non-operative

• Restricted weight-bearing
• Rom brace

Operative

• Arthroscopy
• Subchondral drilling
• Fixation of loose fragment
• Open fixation