Free-floating medial meniscus implant kinematics do not change after simulation of medial open-wedge high tibial osteotomy and notchplasty

PURPOSE: The purpose of this in-vitro study was to examine the kinematics of an artificial, free-floating medial meniscus replacement device under dynamic loading situations and different knee joint states. METHODS: A dynamic knee simulator was used to perform dynamic loading exercises on three neutrally aligned and three 10° valgus aligned (simulating a medial openwedge high tibial osteotomy - MOWHTO) left human cadaveric knee joints. The knee joints were tested in three states (intact, conventional notchplasty, extended notchplasty) while 11 randomised exercises were simulated (jump landing, squatting, tibial rotation and axial ground impacts at 10°, 30° and 60° knee joint flexion) to investigate the knee joint and implant kinematics by means of rigidly attached reflective marker sets and an according motion analysis. RESULTS: The maximum implant translation relative to the tibial plateau was < 13 mm and the maximum implant rotation was < 19° for all exercises. Both, the notchplasties and the valgus knee alignment did not affect the device kinematics. CONCLUSIONS: The results of the present in-vitro study showed that the non-anchored free-floating device remains within the medial knee joint gap under challenging dynamic loading situations without indicating any luxation tendencies. This also provides initial benchtop evidence that the device offers suitable stability and kinematic behaviour to be considered a potential alternative to meniscus allograft transplantation in combination with an MOWHTO, potentially expanding the patient collective in the future.