Abstract
Purpose of the study: Navigation systems have proven their capacity to improve the quuality of total knee arthroplasty (TKA) implantation. The navigation system coud also be used to record knee kinematics intraoperatively.
Material and methods: Twenty TKA implantations were studied. The series included six males and 14 females, mean age 71 years (range 63–78 years). All underwent surgery for overall osteoarthritis. A TKA with a mobile plateau was implanted with preservation of the posterior cruciate ligament. The OrthoPilot® imageless navigation system (Aesculap, Tuttlingen, German) was used. The software was modified to enable recording the relative movement of the femur in relation to the tibia during flexion-extension movements. Infrared locators were fixed on the lower part of the femur and the proximal part of the tibia. After kinematic and anatomic acquisition of conventional navigation data, the kinematic recordings were made during passive flexion-extension before performing any procedures on the bones. The system recorded femur rotation in relation to the tibia in the frontal plane (varus-valgus), in the sagittal plane (flexion-extension), and in the horizontal plane (internal-external rotation) as well as anteroposterior translation of the femur on the tibia. The prosthesis was implanted using the conventional navigation technique. After implantation, the same kinematic recordings were repeated. Each measurement was taken in duplicate to study reproducibility in the same patient. Pre- and postoperative kinematic recordings in the same patient were compared to obtain objective evidence of changes induced by prosthesis implantation. The pre- and postoperative results were compared with those reported to date in the literature.
Results: The recorded kinematic curves, both before and after TKA implantation, were coherent with generally accepted values, particularly for rotation and antero-posterior translation. Paradoxical kinematic recordings were noted after implantation. There was no significant difference between the two recordings in the same patient.
Discussion: The software enables a reliable study of knee kinematics before and after TKA implantation. This could be useful to test new prosthetic solutions, but also to choose for a given patient, the best kinematic compromise. It would be interesting to compare these results with data on in vivo kinematic recordings made in the same patients.
Conclusion: Intraoperative kinematic analysis is a research tool at the present time, but could be useful to improve the quality of TKA implantations.
Correspondence should be addressed to SOFCOT, 56 rue Boissonade, 75014 Paris, France.
