Beyond conversion to TKA: selective tibial component revision for failed medial UKA (case report)

Unicompartmental knee arthroplasty (UKA) can offer faster recovery and less surgical trauma than total knee arthroplasty (TKA) when osteoarthritis is confined to one compartment, but it carries a higher revision risk. When UKA fails, conversion to TKA is most common. Selective (component-only) revision is controversial because registry studies report higher re-revision rates.

A 60-year-old man developed aseptic loosening of the tibial component 6 months after a cemented medial UKA. Infection was excluded, and imaging/clinical assessment confirmed a well-fixed femoral component, intact ligaments, and no progression in the lateral or patellofemoral compartments. After shared decision-making, we revised only the loose tibial component and exchanged the polyethylene insert. At 36 months, the patient had no pain or functional limitation, Knee Society Scores of 89 (knee) and 90 (function), WOMAC 13/96, and no radiographic loosening.

Early isolated tibial loosening is most consistent with technical or mechanical factors (alignment, fixation, and micromotion) rather than biological failure. This report details evaluation steps, operative considerations, and counseling points, and proposes an algorithm for selecting selective tibial revision versus conversion to TKA.

Selective tibial revision may succeed in highly selected patients, but conversion to TKA remains the standard. Patients should be counseled that registry and comparative studies suggest higher re-revision rates after UKA-to-UKA revisions.