Original ArticleTibial Forces Measured In Vivo After Total Knee Arthroplasty
Section snippets
Transducers
A titanium alloy revision tibial prosthesis design was instrumented with force transducers, a microtransmitter, and an antenna. The tibial force transducers have been previously described [1] and have been used in cadaveric studies 36, 37. The tibial tray consists of upper and lower halves separated by support posts, below which lie the load cells. The load cells are located at the 4 quadrants of the tibial tray. By measuring the force on each load cell, the total axial load, and the location
Preoperative and Intraoperative Results
Based on ankle accelerometer measurements, the patient walked an average of 1.6 million steps per year before the surgery. Passive knee flexion demonstrated reasonable balance between the medial and lateral soft tissues intraoperatively. The mean mediolateral imbalance (difference between the medial and lateral forces) was 6 (±1.1) N, and the mean anteroposterior imbalance was 11 (±2.4) N.
Postoperative Rehabilitation
The patient was able to bear weight on the operated limb with the help of a walker on postoperative day 1,
Discussion
This report represents the first in vivo measurements of forces directly at the tibial tray after total knee arthroplasty. Tibial forces have been measured in vitro using a tibial plate connected to an instrumented shaft [38]. Singerman et al [39] also measured forces in cadaver knees using a force transducer design based on 2 concentric cylinders. Kaufman et al [1] reported on a tibial prosthesis instrumented with load cells that could measure the magnitude of compressive force and the center
Acknowledgments
This study was funded in part by OREF research grant 02-021, a research grant from the Knee Society, and the Weingart-Price Fund.
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Cited by (0)
Benefits or funds were received in partial or total support of the research material described in this article. These benefits or support were received from the following sources: OREF research grant 02-021, a research grant from the Knee Society, and the Weingart-Price Fund. No funding was received from Depuy; however John Slamin is an employee.
This study has been awarded the 2004 HAP Paul Award.