21: Orthopaedic Knee Conditions

Question 1

label the ligaments and menisci of the knee joint

Answer 1

Question 2

what is the function of meniscii?

Answer 2

• specialised c-shaped cartilages which aid force transmission and increase stability of the knee joint

Question 3

are medial or lateral meniscus tears more common?

Answer 3

medial

Question 4

meniscal tear presentation and examination clues

use LOOK, FEEL, MOVE for exam clues

Answer 4

presentation:
- pain
- clicking
- locking
- intermittent swelling

examination:
- LOOK: effusion
- FEEL: tender joint line at point of tear (esp. medial tear)
- MOVE: mechanical block to movement, McMurrays test +, fail deep squat, Thassaly’s test +

Question 5

meniscal tear investigations

Answer 5

• history and exam
• x-ray: arthritis, fracture
• MRI: most sensitive test, high false positive rate

Question 6

meniscal tear treatment

Answer 6

Unlikely to heal as poor blood supply

Non-operative:
- rest
- NSAIDs
- physio: hamstring and quads strengthening

Operative:
- arthroscopy: repair or resection

Question 7

what happens in osteoarthritis?

Answer 7

degenerative change of synovial joints:
- progressive loss of articular cartilage
- secondary bony changes

characterised by worsening pain and stiffness of the affected joint

Question 8

what are the conservative management options for osteoarthritis?

Answer 8

• weight loss
• analgesia
• activity modification
• braces
• walking aids
• visco-supplementation
• steroid injections

Question 9

what is the anterior cruciate ligament (ACL) blood supply?

Answer 9

middle geniculate artery

Question 10

what is the innervation of the ACL?

Answer 10

posterior articular nerve, a branch of tibial nerve

Question 11

what is the function of the ACL?

Answer 11

• primary restraint to anterior translation of the tibia relative to femur
• secondary restraint to tibial rotation and varus/valgus stress

Question 12

what typically causes an an ACL tear and what gender does it usually affect?

Answer 12

• non-contact pivot injury
• females:males = 4.5:1

Question 13

ACL tear presentation

Answer 13

• hard a ‘pop’ or ‘crack’
• immediate swelling (70%) and haemarthrosis
• unable to continue playing but can walk in straight line
• deep pain

Question 14

ACL tear examination clues

USE LOOK, FEEL AND MOVE

Answer 14

• LOOK: effusion (if recent injury)
• FEEL: may be tender
• MOVE: anterior draw, Lachmann’s test, Pivot shift > best done under anaesthetic

Question 15

ACL tear imaging

Answer 15

• x-ray: segond fracture > avulsion of anterolateral ligament
• MRI: ACL, meniscii (lateral simultaneous with ACL tear (48%)) medial secondary to shear from chronic insatbility, MCL

Question 16

ACL tear treatment

Answer 16

non-operative:
- focused quadricep programme

operative:
- ACL reconstruction: +/- partial menisectomy +/- ligament reoaur or augmentation, hamstring graft

Question 17

what is the function of the superficial medial cruciate ligament (MCL)?

Answer 17

• primary restraint to valgus stress

Question 18

what is the function of the deep medial cruciate ligament MCL?

Answer 18

• contributes in full knee extension
• attaches to medial meniscus
• continuous with joint capsule

Question 19

what is the most common ligament injury of the knee?

Answer 19

MCL tear

Question 20

what usually causes an MCL tear?

Answer 20

severe valgus stress
- usually contact-related

Question 21

MCL tear presentation

Answer 21

• heard a ‘pop’ or ‘crack’
• pain ++ medial side
• unable to continue playing
• bruised medial knee
• localised swelling

Question 22

MCL tear examination clues

LOOK, FEEL, MOVE

Answer 22

• LOOK: medial swelling and bruising
• FEEL: tender medial joint line, tender femoral insertion of MCL
• MOVE: painful in full extension, opening on valgus stress

Question 23

MCL tear investigations

Answer 23

• history and exam
• x-ray: may be normal, calcification at femoral insertion
• MRI: modality of choice, assess location of injury and identify other pathologies

Question 24

MCL tear treatment

Answer 24

non-operative:
- rest
- NSAIDs
- physio
- brace for comfort

operative (for severe tears, or failed non-operative management):
- repair: avulsions for midsubstance tear with good tissue
- reconstruction: for damaged tissue

Question 25

describe osteochondritis dissecans

Answer 25

• pathological lesion affecting articular cartilage and subchondral bone
• 2 forms: juvenile (10-15 years while growth plates still open) and adult
• posterolateral aspect of medial femoral condyle (70%) of cases in knee

Question 26

causes for osteochondritis dissecans

Answer 26

• hereditary
• traumatic
• vascular: adult form

Question 27

osteochondritis dissecans presentation

Answer 27

• activity-related pain, poorly localised
• recurrent effusions
• mechanical symptoms: locking, block to full movement

Question 28

osteochondritis dissecans examination clues

LOOK, FEEL, MOVE

Answer 28

• LOOK: effusion
• FEEL: localised tenderness
• MOVE: stiffness, block to movement, Wilson’s test

Question 29

osteochondritis dissecans investigations

Answer 29

• history and exam
• x-ray: add on tunnel view (flexed 30-50 degrees)
• MRI: lesion size, status of cartilage and subchondral bone, signal intensity > oedema suggests instability of fragment

Question 30

osteochondritis dissecans treatment

Answer 30

non-operative:
- restricted weight-bearing
- ROM brace

operative:
- arthroscopy: subchondral drilling, fixation of loose fragment
- open fixation