Abstract
We have evaluated the function of a trabecular metal augmentation patella to restore knee kinetics and kinematics after revision total knee arthroplasty. An “Oxford type” rig was used with fresh frozen cadaveric knees, for an active model that maximally retained the soft tissue envelope.
Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.
Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.
The purpose of this study is to evaluate the kinetic and kinematic function of a new trabecular metal augmentation patella.
Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.
Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.
This study demonstrates that the augmentation patella restorers the abnormal tracking and higher extensor mechanism forces seen after patelloplasty in revision TKA to those normal after a TKA.
The mean, maximum extensor mechanism force in extension for the TKA group as compared to the patelloplasty group (p=0.0000032), reduced to near normal with the augmentation patella (p=0.198).
The mean, maximum patella maltracking in extension for the TKA group as compared to the patelloplasty group (p=0.025), reduced to near normal with the augmentation patella (p=0.301).
Eight frozen human cadaveric knees (mean age sixty-eight years) were prepared for an “Oxford type” knee rig. Alignment ands offset were addressed and the soft tissue envelope kept as intact as possible. A load cell was introduced into the extensor mechanism. Femoral, patella and tibial motion were assessed using the Optotrak system.
Patella bone loss at revision TKA remains an unsolved problem, with the patella often too thin to accept a new prosthesis. Leaving the patella shell to articulate against the femoral component can lead to disappointing results.
Funding - Zimmer
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
