The next most common reason for revision was patellofemoral problems (50%), while nearly 60% of patients were found to have multiple causes for failure.

TKR is the treatment of choice for advanced multi-compartmental OA, but 10-30% of patients report ongoing pain and dissatisfaction, often resulting in revision surgery,. The burden of revision TKR is increasing in many countries, and the rate of revision in national joint registries now ranges from 3 to 12%, depending on the observation period and the criteria for a ‘revision’ TKR being applied.

Most literature on the causes of revision TKR has been based on national registry data. Often this analysis is limited to a single cause per revision, and employs no standardised methodology for accurately diagnosing the cause of failure. “This impedes the careful identification or exclusion of all possible failure modes.”

The objective of this study was to assess the most common reasons for primary TKR failures in a large single-centre series using a published, standardised diagnostic algorithm. Data from a specialised knee centre was collected prospectively for patients presenting with persistent post-TKR pain between 2015 and 2020. Revision was defined as a “secondary surgical procedure…where by the complete primary implant or parts thereof are replaced by new components.”

The failure categories used were:

• Aseptic loosening

• Peri-prosthetic infection

• Instability

• Wear/osteolysis