Arthroplasty iSAWE 8

Question

A 66 year old man with anteromedial knee osteoarthritis has had surgery.

Arthroplasty iSAWE 8, AP and lateral radiographs of the knee
AP and lateral radiographs of the knee. Image by MBq Disk, Wikimedia Commons, Public domain.
  1. What procedure has been done?
  2. What are the indications for this procedure?
  3. Compare the outcomes with total knee arthroplasty.

Answer

Procedure

  • Medial unicompartmental knee arthroplasty (fixed bearing)

Indications

  • Anteromedial osteoarthritis with bone on bone medial compartment
  • Functionally intact ACL
  • Correctable varus deformity
  • Full thickness lateral cartilage (valgus stress view)
  • Fixed flexion under 15 degrees
  • Patellofemoral wear is acceptable unless lateral facet bone loss or grooving
  • Age, weight and activity are no longer strict contraindications (Oxford criteria)

Outcomes versus TKA

  • Faster recovery, better range and more natural feel
  • Lower mortality, VTE and infection
  • TOPKAT trial showed similar function at 5 years with lower cost
  • Higher revision rate in registries, about 2 to 3 times TKA
  • Revision rates lower in high volume surgeons using UKA for over 20% of knees
  • Failure from lateral progression, aseptic loosening, bearing dislocation (mobile bearing) and unexplained pain

Related pages

Author Contributions

Orthofracs team

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.