Subcortical Backup Fixation in ACL Reconstruction

Anterior cruciate ligament (ACL) injuries result in knee instability in a majority of patients. Repair and reconstruction techniques have continually evolved over the past several decades. ACL reconstruction outcomes are directly impacted by physical therapy with early range of motion, weightbearing, and progressive strengthening. Therefore, the fixation must be sufficient to withstand the tensile and shear stresses across the graft construct during the biological healing phase. Occasionally, the primary fixation device is not strong enough to withstand these stresses. In turn, supplementary fixation devices, which are important especially in cases of revision ACL reconstruction, are imperfect. They occasionally become symptomatic, requiring hardware removal. Posts and washers require bicortical fixation, with moderate-sized holes in the tibia. Biocomposite screws rely on friction in the bone-screw interface, making them susceptible to failure. Tensioning can be problematic with the use of a post-and-washer construct. Subcortical fixation, which has not previously been described as a backup fixation method, provides several advantages. It requires a smaller, unicortical hole and provides fixation with a much lower profile than post-and-washer and interference-screw constructs. This is the first description of subcortical backup fixation in ACL reconstruction.