T&O: Knee pathology

Question 1

Name 2 causes for patella fracture.

Answer 1

1. direct trauma

2. sudden forceful contraction of quadriceps muscle

Question 2

How do patella fragments displace after fracture?

Answer 2

• Proximal fragment superiorly (pull of quadriceps tendon)

- Distal fragment inferiorly (pull or patellar ligament)

Question 3

How do patellar fragments usually present?

Answer 3

• marked swelling and pain over patella
• point tenderness
• reduction in extension strength
• large joint effusion or haemarthrosis

Question 4

How would you manage transverse fractures of the patella?

Answer 4

modified tension band wiring (K wire technique)

Question 5

In which gender are patella dislocations more common?

Answer 5

Women: greater Q angle (oblique placement of femur relative to tibia)

Question 6

In which direction does the patella usually dislocate? What mechanisms usually resist this?

Answer 6

Laterally due to imbalance between lateral pull and mechanisms resisting this:

• medial more horizontal pull of vastus medialis
• more anterior projection of lateral femoral condyle - deeper slope for larger patellar facet

Question 7

Name 3 X-ray features of patella dislocation.

Answer 7

1. lateral displacement of patella
2. joint effusion
3. sliver sign