Key reason for midterm to long-term medial, lateral UKA revision: OA progression
Despite issues with mobile-bearing lateral unicompartmental knee arthroplasty implants, researchers found similar midterm to long-term survivorship of both lateral and medial unicompartmental knee arthroplasty performed from 2007 to 2017.
Joost A. Burger, DMed, a research fellow at Hospital for Special Surgery in New York, presented results of the retrospective study at the Virtual EFORT Congress.
Burger and colleagues accessed data from the Dutch Arthroplasty Register to compare survivorship of 537 lateral unicompartmental knee arthroplasties (UKAs) and 19,295 medial UKAs with regard to implant and patient characteristics.
“The effect of patient characteristics on revision rate was comparable between lateral and medial UKA. However, higher revision rates were observed for mobile bearings compared to fixed bearings on the lateral side; while medially, no difference was observed between mobile and fixed bearings,” Burger said.
“Five-year revision rate was 12.9 for lateral and 9.3 for medial UKA,” he said.
Based on the abstract, researchers found an association of patient characteristics – such as younger age, smoking, having a greater BMI and having prior surgery in the affected knee – with an increased revision rate in patients with either lateral or medial UKAs.
“Progression of osteoarthritis was the main reason for revision on both sides, accompanied by tibial loosening for medial UKA,” Burger said.
“Our findings reflect the differences in anatomy and kinematics between the two compartments and suggest that other surgical principals need to be considered in lateral compared to medial UKA,” he said.
Burger noted limitations of the study included the smaller relative number of lateral UKAs included in the analysis vs. medial UKAs, the inability to determine UKA case volume for the surgeons who did the implantations and “the inability to infer causality.”