Abstract
This study reviewed the revision rate of fully cemented, hybrid and cementless primary total knee replacements (TKR) registered in the New Zealand Joint Registry from 1999 to May 2008 to determine whether there was any significant difference in the survival and reason for revision with these different types of fixation.
The percentage rate of revision was calculated per 100 person years (HPY) and compared to the reason for revision, type of fixation and the patient’s age.
Of the 28707 primary TKR registered, 522 underwent revision procedures requiring change of at least one component with a survival rate of 0.44 HPY (1.8%). The majority of revisions were for pain (153) followed by deep infection (133) followed by loosening of the tibial component (98). Overall the rate of tibial loosening was 0.07 HPY (0.3 %) in the cemented group vs 0.25 HPY (1%) in the cementless group (p < 0.001). There was no significant difference in the type of fixation used for the femoral component, but there was a significant difference in the different types of fixation when revised for pain, with the uncemented tibia performing the poorest. There was no significantly difference in the younger patient (< 55 years) with respect to tibial loosening (p=0.92).
Failure of the uncemented total knee replacement was due to pain and tibial loosening although the results in patients under 55 years were similar in all fixation groups. There was no difference in the fixation method of the femoral component.
Correspondence should be addressed to: Associate Professor N. Susan Stott, Orthopaedic Department, Starship Children’s Hospital, Private Bag 92024, Auckland, New Zealand.
