ABSTRACT: Excessive posterior tibial slope (PTS) is a recognized risk factor for failure of anterior cruciate ligament reconstruction (ACLR) and should be considered when planning a revision ACLR. A tibial supra-tubercular deflexion osteotomy can correct excessive PTS with simultaneous or staged ACLR. There are only a handful of technical descriptions offering insight on the respective authors’ approach at reducing PTS, all of which vary greatly in their methods. The authors describe a surgical technique using a proximal tibial supra-tubercular deflexion osteotomy in patients with persistent knee instability, a history of at least one failed ACLR, and a PTS greater than 12°. This surgery is not recommended in patients with significant genu recurvatum (>10°), significant varus, or severe tibiofemoral osteoarthritis. Technique Video Video 1 This technique video shows important aspects of preoperative planning and the surgical technique for supra-tubercular deflexion osteotomy divided into 10 steps. We start by emphasizing how the height of the osteotomy wedge resected is dependent on tibial width in the sagittal plane. This is clearly shown in the third slide, where Patient A has a longer tibial width in the sagittal plane (green line), when compared to Patient B, and requires a larger anterior wedge resection of 11.7 mm to achieve a target slope of 5°. Patient B, who has the same posterior tibial slope as patient A (17°), requires a shorter anterior wedge resection of 8.4 mm to correct to 5° of posterior tibial slope. The third and fourth slides of the video also depict two ways to calculate the osteotomy wedge height. We recommend calculating osteotomy wedge height (WH) using the following formula, which requires only measurement of the PTS and tibial width (TW): Osteotomy WH X = (TW)∙ tan (resection ∠) where the resection angle (12° in these examples) is the angle of the wedge needed to be removed in order to achieve the desired final PTS (5° in these examples). The second way is an approximation formula, which is derived from tangent but does not include trigonometry in the final formula. The final few slides demonstrate the 10 steps of our technique, which include: 1) scope, hardware removal, and tunnel grafting, 2) midline incision with medial and lateral flaps, 3) location of distal insertion of patellar tendon, 4) placement of 4 pins in a triangular fashion, 5) sawblade cuts between pins, 6) removal of bone wedge, 7) cleaning of site with curette, 8) drill posterior cortex, 9) closing of osteotomy in extension, and 10) fixation with staples.
