Abstract
Introduction
LCS total knee arthroplasty was used in many nations worldwide. This implant's features are not only mobile bearing but also has very unique concepts of mechanism.
Meniscal bearing (MB) is a one of the types of implant. 2 separate bearings move on the tibia plate. This implant has been known to need revision in cases of over ten years. F.F. Buechel1) reported a 5% revision rate at an average of 10.1 years. On the other hand, another type of implant, which is a rotating platform bearing LCS, had only 1.2% at an average of 9.9 years.
Patients and Methods
We used the meniscal bearing type LCS (MB-LCS) 289 knees from May 1995 to Dec. 2005. All cases were supervised by chief surgeon Makoto Kobori. He reported on the long term follow up of LCS until 2006. There were 18 cases revision of the MB-LCS (revision rate 6%) and in all cases only the meniscal bearings were replaced.2) We followed further until April 2014.
Results
After 2006, we have had many revision cases of MB-LCS. We followed on those 289 knees until April 2014. The follow up rate was 76.2% (lost follow up 69 knees / 289 knees). 32 knee revision out of 289 knees of MB. 29 knees had only MB replaced and 3 knees needed to have all components changed. There was one case of infection after replacing MB. The MB-LCS revision rate was 11% at an average of 11 years, which is clearly an increase over other reports.
Discussion
Production of MB-LCS was stopped in recently. Because there was a high revision rate, difficult for surgery due to the unique mechanism and less market share. Buechel said the polyethylene wear problems due to sterilization of the bearing by a gamma irradiation in air process which resulted in high oxidation when left on an inventory shelf.1) Fortunately, MB-LCS revision was easy to replace only the MBs in many knees. However the implant maker stopped making MB, creating an unacceptable problem. t We hope for the continued production of MB for revision surgery.
