Risk of interference between the tibial tunnel and locking screws in medial meniscus posterior root repair and open wedge high tibial osteotomy

Purpose To evaluate whether the frequency of interference between locking screws for the plate fixation and tibial tunnels differs depending on the tibial tunnel positions in a surgical simulation of the transtibial pull-out repair of medial meniscus posterior root tears (MMPRTs) in patients undergoing biplanar open wedge high tibial osteotomy (OWHTO). Methods Sixty-five patients (75 knees) who underwent OWHTO with TomoFix small plate (Depuy Synthes, PA, USA) for medial knee osteoarthritis with varus malalignment were enrolled in this study. Surgical simulation of transtibial pull-out repair of MMPRTs was performed using postoperative computed tomography images. The tibial tunnel was created in the anatomical attachment area of the medial meniscus posterior root. Another aperture of the tibial tunnel was created on the anteromedial (AM) tibial cortex, the posteromedial (PM) tibial cortex, and the anterolateral (AL) tibial cortex in the proximal tibial fragment. The frequency of interference between the tibial tunnel and A-D locking screws was compared in the 3 tibial tunnel positions. In each tibial tunnel position, the locking plate position with and without interference between the tibial tunnel and at least one locking screw was compared. Results For screw A, the frequency of interference with the tibial tunnel in the AL position was higher than that in the AM (P = 0.048) and PM positions (P < 0.001). For screws B and C, the frequency of interference with the tibial tunnel in the AM position was higher than that in the PM (P < 0.001, P = 0.007) and AL positions (P < 0.001, P = 0.001), respectively. For screw D, there was no difference in the frequency of interference with the tibial tunnel among the three positions. The frequency of interference between the tibial tunnel and at least one screw in the AM position was 100%, which was higher than that in the PM (P < 0.001) and AL positions (P < 0.001). In the PM position, the locking plate was placed more posteriorly in the group where the locking screw interfered with the tibial tunnel. In the AL position, the locking plate was placed more parallel to the medial/lateral axis of the tibial plateau in the interference group. Conclusion Making the tibial tunnel in the AM position should be avoided because interference with locking screws was inevitable. When the tibial tunnel is created in the PM position, interference between the tibial tunnel and screw C should be paid attention. Anterior placement of the locking plate could be useful to prevent interference between locking screws and the tibial tunnel in the PM position. In addition, when the tibial tunnel is created in the AL position, interference between the tibial tunnel and especially screw A among screws A-C should be paid attention. Placing the locking plate in an anteromedial direction could be useful to prevent interference between locking screws and the tibial tunnel in the AL position.