Biplanar Anterior Opening Wedge Proximal Tibial Osteotomy to Correct Reverse Tibial Slope

Abstract

Anatomically, native posterior tibial slope (PTS) ranges from 6° to 10° and have significant effects on cruciate ligament stability. PTS <6° is correlated with increased posterior tibial translation (PTT) and force on the posterior cruciate ligament (PCL), predisposing individuals to PCL injuries and an increased risk of PCL graft attenuation. In rare cases, a reverse tibial slope can occur (<0°) as a result of trauma, physeal arrest, or abnormal development. This results in increased PTT and can lead to posterior tibial subluxation. Reverse tibial slopes in patients can be treated with an anterior opening wedge proximal tibial osteotomy, which increases the PTS to a more anatomic position. Biplanar anterior opening wedge proximal tibial osteotomies are indicated in patients with a reverse tibial slope both with the absence of PCL insufficiency or in conjunction with PCL reconstruction. Under fluoroscopic imaging, 2 guide pins were placed perpendicular to the tibial shaft. An oscillating saw and osteotomes completed the osteotomy in line with the guide pins with the posterior cortex remaining intact. The osteotomy site was slowly opened with a spreader device to 9 mm until the posterior drawer was such that the palpable step-off between the anterior aspect of the medial femoral condyle and the medial tibial plateau was comparable to the contralateral knee. Due to the patient having slight valgus coronal plane alignment, an opening-wedge posteriorly sloped plate was then placed anterolaterally and fixed while wedges held the osteotomy open. Biplanar anterior opening wedge osteotomies correct a flattened PTS and reverse tibial slope, and coronal malalignment, and has been shown to decrease PCL laxity, preventing future PCL failure. Biomechanical studies have shown that decreased tibial slope is correlated with an increased risk of PCL injury and PCL graft failure. In patients with reverse tibial slope, experienced instability can mimic PCL insufficiency despite there being no ligamentous damage. We describe a technique that corrects reverse tibial slope and with a discussion of surgical pearls and pitfalls. This technique restores anatomic position and normal function of the knee while correcting the sagittal malalignment that could lead to future injuries. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.