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arthroplasty

Unicompartmental Knee Arthroplasty

intermediate
6 min
20 marks
6 questions
Clinical Scenario
A 62-year-old male with medial compartment osteoarthritis presents considering surgical options. He has an active lifestyle and is a keen golfer, hoping to return to sport. He has tried physiotherapy, injections, and activity modification without sufficient relief. On examination, he has varus alignment passively correctable to neutral, full extension, and flexion to 125°. His ACL is intact. Weight-bearing radiographs confirm isolated medial compartment bone-on-bone changes with preserved lateral and patellofemoral compartments.
Weight-bearing AP radiograph showing isolated medial compartment osteoarthritis with bone-on-bone changes. Lateral compartment and patellofemoral joint are preserved. Varus deformity appears passively correctable.
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Weight-bearing AP radiograph showing isolated medial compartment osteoarthritis with bone-on-bone changes. Lateral compartment and patellofemoral joint are preserved. Varus deformity appears passively correctable.

Source: Medial Compartment Osteoarthritis Radiograph • PMC3615296 • CC-BY

Questions

Question 1 (4 marks)

What are the indications and contraindications for unicompartmental knee arthroplasty?

Question 2 (3 marks)

What clinical examination findings would support UKA candidacy?

Question 3 (3 marks)

What are the advantages of UKA over TKA in appropriate candidates?

Question 4 (3 marks)

What outcomes and complications would you discuss with the patient?

Question 5 (4 marks)

If this patient returns 7 years later with lateral compartment progression, what are your management options?

Question 6 (3 marks)

What are the technical considerations for conversion from UKA to TKA?

Exam Day Cheat Sheet

Must Mention

  • •ACL MUST BE INTACT for UKA
  • •Isolated single compartment disease
  • •Correctable deformity <15°
  • •No significant patellofemoral disease (especially lateral facet)
  • •No inflammatory arthritis
  • •Fixed flexion <10°, arc of motion >90°
  • •AOANJRR: higher revision rate than TKA overall, but good outcomes in appropriate candidates

Common Pitfalls

  • •UKA with deficient ACL (will fail)
  • •Missing patellofemoral disease on skyline
  • •Not checking lateral compartment with valgus stress
  • •Fixed flexion deformity not correctable
  • •Inflammatory arthritis (RA)