Knee meniscus tears

Question 1

Knee ruptured anterior cruciate ligament

Answer 1

Sport injury
Mechanism: high twisting force applied to a bent knee
Typically presents with: loud crack, pain and RAPID joint swelling (haemoarthrosis)
sudden ‘popping’ sound
knee swelling
instability, feeling that knee will give way

Poor healing

anterior draw test
the patient lies supine with the knee at 90 degrees
the examiner should place one hand behind the tibia and the other grasping the patient’s thigh. It is important that the examiner’s thumb be on the tibial tuberosity
the tibia is pulled forward to assess the amount of anterior motion of the tibia in comparison to the femur
an intact ACL should prevent forward translational movement
Lachman’s test
variant of anterior draw test, but the knee is at 20-30 degrees
evaluate the anterior translation of the tibia in relation to the femur and is considered a variant
more reliable than anterior draw test

Management: intense physiotherapy or surgery

Question 2

Knee ruptured posterior cruciate ligament

Answer 2

Mechanism: hyperextension injuries–Damage may occur following dashboard injuries
Tibia lies back on the femur
Paradoxical anterior draw test

Question 3

Knee ruptured median collateral ligament

Answer 3

Mechanism: leg forced into valgus via force outside the leg– Damage may commonly result from skiing and following valgus stress
Damage typically causes abnormal passive abduction of the knee

Knee unstable when put into valgus position

Question 4

Menisceal tears

Answer 4

Rotational sporting injuries
Delayed knee swelling
Joint locking (Patient may develop skills to ‘unlock’ the knee)
Damage may result from twisting injuries
Locking and giving way are common symptoms
pain worse on straightening the knee
Recurrent episodes of pain and effusions are common, often following minor trauma

Thessaly’s test - weight bearing at 20 degrees of knee flexion, patient supported by doctor, positive if pain on twisting knee
tenderness along the joint line

Question 5

Chondramicia patellae

Answer 5

Teenage girls, following an injury to knee e.g. Dislocation patella
Typical history of pain on going downstairs or at rest
Tenderness, quadriceps wasting

Question 6

Patellar dislocations

Answer 6

Most commonly occurs as a traumatic primary event, either through direct trauma or through severe contraction of quadriceps with knee stretched in valgus and external rotation
Genu valgum, tibial torsion and high riding patella are risk factors
Skyline x-ray views of patella are required, although displaced patella may be clinically obvious
An osteochondral fracture is present in 5%
The condition has a 20% recurrence rate

Question 7

fractures of patella

Answer 7

2 types:
i. Direct blow to patella causing undisplaced fragments
ii. Avulsion fracture

Question 8

tibial plateau fracture

Answer 8

Occur in the elderly (or following significant trauma in young)
Mechanism: knee forced into valgus or varus, but the knee fractures before the ligaments rupture
Varus injury affects medial plateau and if valgus injury, lateral plateau depressed fracture occurs
Classified using the Schatzker system (see below)

Question 9

Schatzker system (see below) of tibial plateau fracture

Answer 9

1 Vertical split of lateral condyle Fracture through dense bone, usually in the young. It may be virtually undisplaced, or the condylar fragment may be pushed inferiorly and tilted

2 Vertical split of the lateral condyle combined with an adjacent load bearing part of the condyle The wedge fragment (which may be of variable size), is displaced laterally; the joint is widened. Untreated, a valgus deformity may develop

3 Depression of the articular surface with intact condylar rim The split does not extend to the edge of the plateau. Depressed fragments may be firmly embedded in subchondral bone, the joint is stable

4 Fragment of the medial tibial condyle Two injuries are seen in this category; (1) a depressed fracture of osteoporotic bone in the elderly. (2) a high energy fracture resulting in a condylar split that runs from the intercondylar eminence to the medial cortex. Associated ligamentous injury may be severe

5 Fracture of both condyles Both condyles fractured but the column of the metaphysis remains in continuity with the tibial shaft

6 Combined condylar and subcondylar fractures High energy fracture with marked comminution

Question 10

Unhappy triad of knee pain/trauma

Answer 10

Unhappy triad is commonly seen following a lateral blow to the knee and consists of damage to the:
anterior cruciate ligament
medial collateral ligament
meniscus (classically the medial meniscus but recent evidence shows that the lateral meniscus is more commonly injured)

Question 11

Straight leg raise interpretations

Answer 11

Raise the leg by examiner from flat to 90 degrees
if pain happens before 70 degrees, and is in the legs-> neuro compression
If pain happens after 70 degrees, and is in the legs-> Muscle/Bone
if pain before 70 degrees only in back- Disc