Abstract
To analyze the mechanism of failure and basic cause in cases of early failure which were required revision within 5 years index TKA. Between 1991 and 2006, 167 revisions TKA of aseptic failure were performed. Revision diagnosis or reason for failure were categorized as wear of tibial polyethylene insert, failure of tibial base plate, early imbalance between medial and lateral soft tension, tight or loose PCL and posterior capsule. The percentages of each failure category were calculated as a percentage of the overall number of revision TKA and a percentage of the early failures. A descriptive statistics were calculated for the time in situ for each failure category.
Early failure within 5 years following index TKA occurred in 33 out of 167 TKA(20.0%). Average time in situ was 38.53 months(3.21 years). Wear of the tibial polyethylene insert occurred in 12 out of 33 cases(36.4%). All cases showed tight PCL. Loosening was the second leading cause occurring in 9 cases(27.2%). Pure instability with tight MCL occurred in 3 knees. Catastrophic early wear within one year after index surgery occurred in 18 knees. The cause of failure were flat surfaced poly in 11, fracture of metal tray 2, dislocation of the thick poly insert 1 and early poly wear due to unknown cause 4.
There were multiple factors of the early failure, which could be divided into design failure and surgical skill failure. However, they worked together in most of the cases.
Correspondence should be addressed to ISTA Secretariat, PO Box 6564, Auburn, CA 95604, USA. Tel: 1-916-454-9884, Fax: 1-916-454-9882, Email: ista@pacbell.net
