Reducing the Risk of Neurovascular Injury With Posteromedial Plating and Laterally Directed Screw Insertion During Opening-Wedge High Tibial Osteotomy

Background: Neurovascular injury is a serious complication after opening-wedge high tibial osteotomy (OWHTO). Purpose: To evaluate (1) how neurovascular injuries during fixation can be prevented and (2) whether a lateral hinge-directed posteromedial fixation system provides comparable neurovascular safety during OWHTO to conventional and custom-made locking plate systems. Study Design: Cohort study; Level of evidence, 3. Methods: Included were 275 knees that underwent OWHTO from March 2014 to May 2018. The knees were divided into 4 groups based on the type of fixation system used: (1) lateral hinge-directed system (LCfit HTO; LCfit group), (2) TDM decisive wedge locking plate (TDM group), (3) OhtoFix anatomic locking metal block plate (OhtoFix group), and (4) TomoFix titanium locking plate (TomoFix group). Using postoperative computed tomography, the following variables among the groups were compared: screw insertion angle relative to the tibia posterior cortex in the axial plane, length, proximity to neurovascular structures, and safety angle of screw fixation (angle between the most proximal posterior screw insertion line and a line tangent to the popliteal artery from the screw hole). Radiological and clinical outcomes were also compared between groups. Results: The screw angle was significantly smaller and the distance from neurovascular structures to the screw extension line was significantly farther in the LCfit group compared with the other 3 groups (P < .001 for both). The safety angle was also wider in the LCfit group than in the other groups (P < .001). There were no significant differences in radiologic or clinical outcomes between the groups during follow-up. Conclusion: The distance from the neurovascular structures to the screw extension line was significantly farther, and the safety angle was also significantly wider with the laterally directed posteromedial plate system compared with the other systems. There were no neurovascular injuries in any group or significant differences in clinical outcomes or radiological parameters between the LCfit and the other locking plate systems.