TOPKAT is the largest RCT directly comparing partial knee replacement (PKR) with total knee replacement (TKR) for medial compartment osteoarthritis. 528 patients across 27 UK hospitals were followed for 5 years, with Oxford Knee Score as the primary endpoint. The trial was designed to resolve persistent uncertainty about whether PKR's perceived higher revision risk outweighs its potential functional and cost advantages.
For years, registry data showing PKR revision rates more than double those of TKR drove many surgeons toward routine TKR for medial compartment OA — even in patients who met criteria for the less invasive procedure. TOPKAT challenges that practice directly.
When your patient has isolated medial compartment OA with an intact ACL, preserved lateral cartilage, and correctable varus deformity, PKR in experienced hands delivers equivalent 5-year function at lower cost and with similar revision risk to TKR.
The key caveat the authors emphasize: the low revision rates in TOPKAT likely reflect the experience floor built into the trial (minimum 10 PKR cases/year). PKR is a volume-sensitive operation. The registry-trial discrepancy is real — and surgeon volume, not implant design, appears to be the explanation.
Refer patients requiring PKR to high-volume operators. The 47% eligibility vs 9% utilization gap tells you this procedure is underused.
TOPKAT is the largest RCT directly comparing partial knee replacement (PKR) with total knee replacement (TKR) for medial compartment osteoarthritis. 528 patients across 27 UK hospitals were followed for 5 years, with Oxford Knee Score as the primary endpoint. The trial was designed to resolve persistent uncertainty about whether PKR's perceived higher revision risk outweighs its potential functional and cost advantages.
For years, registry data showing PKR revision rates more than double those of TKR drove many surgeons toward routine TKR for medial compartment OA — even in patients who met criteria for the less invasive procedure. TOPKAT challenges that practice directly.
When your patient has isolated medial compartment OA with an intact ACL, preserved lateral cartilage, and correctable varus deformity, PKR in experienced hands delivers equivalent 5-year function at lower cost and with similar revision risk to TKR.
The key caveat the authors emphasize: the low revision rates in TOPKAT likely reflect the experience floor built into the trial (minimum 10 PKR cases/year). PKR is a volume-sensitive operation. The registry-trial discrepancy is real — and surgeon volume, not implant design, appears to be the explanation.
Refer patients requiring PKR to high-volume operators. The 47% eligibility vs 9% utilization gap tells you this procedure is underused.