Unicompartmental Knee

Question 1

What are the contraindications to a unicompartmental knee arthroplasty?

Answer 1

1) Inflammatory arthritis
2) Deficient ACL or PCL
3) Fixed varus >10 degrees and fixed valgus >5 degrees
4) Tricompartmental arthritis
5) Flexion contracture > 5-10 degrees

Question 2

What is the survivorship of a mobile bearing unicompartmental knee?

Answer 2

93% survivorship at 15yrs; lateral compartment results are equal to medial.

Question 3

What are the advantages of uni-knee compared to TKA?

Answer 3

1) faster rehabilitation and quicker recovery
2) less blood loss
3) less morbidity
4) less expensive
5) preservation of normal kinematics

Question 4

What are the signs of a stress fracture following uni-knee replacement?

Answer 4

1) Pain free interval followed by spontaneous onset of pain
2) Normal radiographs with increased uptake on bone scan
3) Lipohematoma on aspirate