Knee Injury

Question 1

Ruptured ACL

Answer 1

• Sport injury
• Mechanism - high twisting force applied to bent knee
• Typically present with loud crack, pain and rapig joint swelling (haemarthrosis)
• Poor healing
• Manage with intense physiotherapy or surgery

Question 2

Ruptured PCL

Answer 2

• Mechanism - hyperextension injuries
• Tibia lies back on the femur
• Paradoxical anterior drawer test
• May occur from dashboard injury

Question 3

Ruptured MCL

Answer 3

• Mechanism - leg forced into valgus via force outside the leg
• Knee instable when put into valgus position
• May commonly result from skiing

Question 4

Meniscal tear

Answer 4

• Rotational sporting injuries
• Delayed knee swelling
• Joint locking (patient may develop skills to ‘unlock’ the knee)
• Recurrent episodes of pain and effusions are common, often following minor trauma

Question 5

Chondromalacia patellae

Answer 5

• Teenage girls, following an injury to knee (i.e. dislocation patella)
• Typical history of pain on going downatairs or at rest
• Tenderness, quadriceps wasting

Question 6

Dislocation of the patella

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

Fractured patella

Answer 7

• Two types:
  
  • Direct blow causing undisplaced fragments
  • 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
• Schatzker Classification system used

Question 9

Quadriceps and patella tendon ruptures

Answer 9

• Presentation
  
  • M>F
  • Eccentric loading of the knee extensor mechanism
  • Often pain leading up to rupture consistent with underlying tendonopathy
  • Tenderness at site of rupture
  • Palpable defect usually within 2cm of superior pole of patella
  • Unable to extend knee against resistance
  • Unable to perform a straight leg raise with complete rupture
• Management
  
  • Knee immobilisation in brace for partial tear with intact knee extensor mechanism and for patients who cannot tolerate surgery
  • Operative primary repair with reattachment to patella