Causes and Treatments of the Early Failure after Unicompartmental Knee Arthroplasty

ABSTRACT

PURPOSE: We wanted to evaluate the causes, treatments and preventive measures for early failure of unicompartmental knee arthroplasty (UKA) by performing an analysis of the cases. MATERIALS AND METHODS: We retrospectively analyzed 687 cases of UKA that had been performed from January 2002 to December 2006. There are 622 cases of the meniscal bearing type, 31 cases of the tracked bearing type and 34 cases of the fixed bearing type. All of the cases were performed by minimally invasive surgery. RESULTS: Early failures after UKA were seen in 36 cases, and these failures occurred from 4 months postoperatively to 5 years 7 months postoperatively. There were 20 mobile bearing dislocations, 18 femoral or tibial component loosenings, 4 infections, 1 medial tibial condylar fracture and 1 case of pain of unknown origin. The most common cause of the failed cases of the meniscal bearing type was bearing dislocation. All of the failed cases of the tracked and fixed types were from loosening of the component. Simple dislocations of bearing were treated by bearing change. All of the other cases were treated with revision TKA or UKA. CONCLUSION: Selection of an appropriate prosthesis and accurate surgical technique are needed to improve the clinical results and reduce failures. Open bearing change can be done for the cases of simple bearing dislocation, and revision TKA is needed if this is accompanied by other complications.