Orthopaedic knee conditions

Question 1

What are the different key ligaments of the knee?

Answer 1

Cruciate ligaments – ACL, PCL. Collateral ligaments: MCL, LCL.

Question 2

Describe menisci and their function

Answer 2

Specialised C-shaped cartilages – triangular in cross-section, medial – attached to deep MCL, lateral. Function – aid force transmission, increase stability.

Question 3

What are the causes of meniscal tear? (acute + degenerative)

Answer 3

Acute – twisting especially in deep flexion. Degenerative – OA.
Medial meniscal tears more common – more fixed structure.

Question 4

Describe the symptoms of a meniscal tear

Answer 4

Pain, Clicking, Locking, Intermittent swelling.

Question 5

Describe the examination of a meniscal tear

Answer 5

LOOK – effusion. FEEL – tender joint line at point of tear. MOVE – mechanical block to movement, fail deep squat, McMurrays test positive, Thessaly’s test positive.

Question 6

What investigations would you carry out for a meniscal tear?

Answer 6

X-ray – arthritis, fracture. MRI – most sensitive test

Question 7

How do you treat a meniscal tear?

Answer 7

Unlikely to heal if poor blood supply.
Non-operative: rest, NSAIDs, physiotherapy – hamstring and quadriceps strengthening.
Operative: Arthroscopy – repair, resection.

Question 8

How do you treat knee OA?

Answer 8

Weight loss, analgesia, activity modification, braces, walking aids, visco-supplementation, steroid injection.
Total knee replacement – cruciate retaining or cruciate sacrificing.

Question 9

What is the function of the ACL?

Answer 9

Primary restraint to anterior translation of the tibia relative to femur, secondary restraint to tibial rotation and Varus/valgus stress.

Question 10

What kind of injury is an ACL tear?

Answer 10

Non-contact pivot injury. Sudden stop or changes in direction, jumping and landing e.g. football, rugby etc. Affects females more - difference in landing biomechanics neuromuscular activation patterns.

Question 11

Describe the presentation of an ACL tear

Answer 11

Heard a ‘pop’ or ‘crack’.
Immediate swelling (70%): haemarthrosis (bleeding into joint).
Unable to continue playing – can walk in straight line.
Deep pain.

Question 12

Describe the examination of an ACL tear

Answer 12

LOOK – effusion (if recent injury). FEEL. MOVE – anterior draw, Lachman’s test, Pivot shift – best done under anaesthetic.

Question 13

Describe the investigation of an ACL tear

Answer 13

X-ray: Segond fracture – avulsion (pulling/tearing away) # of anterolateral ligament. MRI – ACL, Meniscii (lateral tear – simultaneous with ACL tear (48%); medial – secondary to shear from chronic instability), MCL.

Question 14

How would you treat an ACL tear?

Answer 14

Non-operative: focussed quadriceps programme. Operative: ACL reconstruction – +/- partial meniscectomy +/- ligament repair or augmentation; hamstring graft.

Question 15

What is the function of superficial and deep MCL?

Answer 15

Superficial – primary restraint to valgus stress.

Deep – contributes to full knee extension, attaches to medial meniscus, continuous with joint capsule.

Question 16

What kind of injury is MCL tear?

Answer 16

Most common ligament injury of the knee. Severe valgus stress – usually contact-related, associated injuries – ACL tear, meniscal tear.

Question 17

Describe the presentation of an MCL tear

Answer 17

Heard a ‘pop’ or ‘crack’.
Pain++ (medial side)
Unable to continue playing.
Bruising medial knee.
Localised swelling.

Question 18

Describe the examination of an MCL tear

Answer 18

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

Question 19

How do you investigate an MCL tear?

Answer 19

X-ray – may be normal, calcification at femoral insertion (Pelligrini-Stieda) – chronic injury. MRI – modality of choice, assess location and severity of injury, identify other pathologies.

Question 20

What are the treatments for an MCL tear?

Answer 20

Non-operative – majority, rest, NSAIDs, physiotherapy, brace for comfort.
Operative – severe tears, failed non-operative treatment. Repair or reconstruction. Repair: avulsions, midsubstance tear with good tissue; Reconstruction: damaged tissue.

Question 21

What is Osteochondritis Dissecans?

Answer 21

Pathological lesion affecting articular cartilage and subchondral bone, 2 forms – juvenile (10-15 years while growth plates still open) + adult.

Question 22

What are the causes of osteochondritis dissecans?

Answer 22

Cause – hereditary, traumatic, vascular (Adult form).

Question 23

Where does osteochondritis dissecans usually affect?

Answer 23

Knee = most common location, posterolateral aspect of medial femoral condyle.

Question 24

What are the symptoms of osteochondritis Dissecans?

Answer 24

Activity-related pain – poorly localised. Recurrent effusions. Locking, block to full movement.

Question 25

What would you see on examination of osteochondritis Dissecans?

Answer 25

May be normal. LOOK – effusion. FEEL – localised tenderness. MOVE – stiffness, block to movement, Wilson’s test.

Question 26

How would you investigate osteochondritis Dissecans?

Answer 26

X-ray – add in tunnel view (flexed 30-50 degrees)

MRI – lesion size, status of cartilage and subchondral bone, signal intensity – oedema suggest instability of fragment.

Question 27

How would you treat osteochondritis Dissecans?

Answer 27

Non-operative – restricted weight bearing, ROM brace. Operative: arthroscopy – subchondral drilling + fixation of loose fragment, open fixation.