Abstract
Purpose: Patellar Clunk is associated with posterior stabilized (PS) femoral components in which a scarred synovial suprapatellar nodule catches on the femoral box with active extension of the flexed knee. We investigated whether a rotating platform tibial component increases the incidence of patellar clunk.
Methods: From December 1998 to June 2006, a single surgeon performed 659 primary TKAs. 329 fixed-bearing tibial components and 330 rotating platforms were implanted. The same PS femoral component was used in all cases. All components were from the PFC Sigma Total Knee System (DePuy, Warsaw, IN, USA). The incidence of patellar clunk requiring reoperation was evaluated prospectively.
Results: There were 17 arthroscopies performed on 16 knees in 15 patients. One patient required bilateral arthroscopies, and one a repeat arthroscopy. 6 (1.8%) arthroscopies were required in the fixed bearing group, and 10 (3%) in the rotating platform group (p< 0.10 NS). The repeat arthroscopy was in the rotating platform group. Time to arthroscopy from the index surgery was 13.6 months (Range 5–40) for the entire group, 15.2 months (Range 8–40) for the fixed-bearing group, and 12.6 months (Range 5–20) for the rotating platform group (p< 0.10 NS).
Conclusions: The incidence of patellar clunk is not increased by the use of a rotating platform tibial component in TKA. While the mobile bearing may improve patellar tracking, causing the extensor mechanism to seat deeper in the trochlear groove, it does not seem to represent a risk factor for the development of the suprapatellar scarring that predisposes to patellar clunk.
Correspondence should be addressed to: Orah Naor, IOA Secretary and Co-ordinator (email: ioanaor@netvision.net.il)
