Extract
The Optetrak total knee arthroplasty system (Exactech, Gainesville,
Florida) is the fifth in a series of total knee arthroplasty designs developed
at the Hospital for Special
Surgery1-3.
The Optetrak implant retains the design concepts of the previous posterior
stabilized Insall-Burstein-I (IB-I PS; Johnson and Johnson, Braintree,
Massachusetts; Zimmer, Warsaw, Indiana) and Insall-Burstein-II (IB-II PS;
Zimmer) posterior stabilized total knee
implants2,4-7.A constrained condylar knee version of the Optetrak design has an elevated
tibial post that, because of its higher and more squared design in comparison
with standard posterior stabilized designs, provides greater varus-valgus and
anteroposterior stability. The modular femoral and tibial components can
accommodate stems through a taper junction. Traditionally, constrained
condylar devices have been used with stem extensions to augment component
fixation. The stem transfers the bending and torsion loads to the diaphysis
and unloads the epiphyseal cancellous bone. From 1995 to 2006, 3886 of these
constrained condylar stems were implanted at our institution. We report the
cases of two patients who had failure in the male portion of the taper
junction of the femoral component and stem extension. This study was performed
under a protocol approved by the institutional review board of the Hospital
for Special Surgery. Both patients were informed that data concerning the
cases would be submitted for publication, and they consented.