NAVIGATION OF KNEE REVISION ARTHROPLASTY USING A SYSTEM DESIGNED FOR PRIMARY SURGERY

Abstract

Introduction: Fifteen revision knee arthroplasties were navigated (Praxim, Grenoble, France). The purpose was to investigate whether revision procedures would require a dedicated navigation system.

Material: Two prostheses were revised for severe instability, two for catastrophic failure due to poly wear, 9 for loosening (1 femoral, 1 tibial and 3 both components in total knee arthroplasties, 3 femoral and 1 tibial in uni), two for late infection in extensively cemented prosthesis. The patients were revised using TC3 postero-stabilised revision implants (Depuy, Warsaw, Indiana) and one with hinge prosthesis.

Method: Preoperatively, the rotation of the femoral component was investigated by scanner, and the ideal level of the joint line was determined relative to the fibula head on the healthy contralateral side.

Navigation was performed with dependant bone cuts, tibia first. The tibial trackers were implanted distally, while the femoral trackers were implanted medially close to the joint line, to prevent impingement with the stems.

Bone morphing was performed on the surface of the ancient prosthesis. The system showed the difference between the level of the ideal joint line and the real bone cut, thus indicating the height that had to be reconstructed. The provisional tibial plateau was assembled with its stem and its metallic augments and the knee was balanced with the new tibial component and the ancient femoral component still in place. Femoral reconstruction was finally performed based on an ideal position that had memorized by the computer

Bone reconstruction was required in 2 tibias (morselized allografts) and in one femur (structural femoral head allografts).

Results: With a 6-months minimum follow-up, there was no postoperative complication. The HKA angles ranged from 176 to 185. The patella appeared centered on the Merchant view in 14 cases. The femoral rotation was contained between 0 and 5 degrees of external rotation. The 6 month ranges of flexion were 105° with an average gain of −4°.

Conclusion: The navigation was a precious help to guide reconstruction of both extremities tibial and femoral, while maintaining the level of the joint line. The navigation system designed for primary surgery appeared convenient to perform revision surgery.