Tibial Slope Can Be Maintained During Medial Opening-Wedge Proximal Tibial Osteotomy With Sagittally Oriented Hinge, Posterior Plate Position, and Knee Hyperextension: A Cadaveric Study

摘要

Purpose: The purpose of this study is (1) to determine if, when optimizing modern techniques, medial opening-wedge osteotomies can effectively maintain tibial slope and (2) to determine how different magnitude coronal plane corrections affect tibial slope. Methods: Proximal tibial osteotomies (PTOs) were performed on 10 fresh-frozen cadaveric knees leaving a consistent lateral hinge, using either a 5-mm or a 10-mm trapezoidal wedged osteotomy plate. Techniques including posterior plate placement; a trapezoidal, sloped plate; and knee hyperextension were used during plate fixation to help close the anterior osteotomy gap. Medial coronal proximal tibia angle and posterior tibial slope were measured preosteotomy, after a 5-mm implant, and after a 10-mm implant using true anteroposterior and lateral fluoroscopic images. Three independent observers performed all radiographic measurements, and intraclass correlation coefficients were calculated. Results: The 5-mm and 10-mm osteotomy plates increased the coronal medial proximal tibia angle by a mean of 3.4 degrees (range, 3.0 degrees-3.7 degrees) and 7.3 degrees (range, 6.7 degrees-7.7 degrees), respectively. The 5-mm and 10-mm trapezoidal wedged osteotomy plates decreased the posterior tibial slope by a mean of 0.9 degrees (range, 0.5 degrees-1.2 degrees) and 0.3 degrees (range, 0 degrees-0.6 degrees), respectively. Intraobserver reliability was found to be high for both the coronal medial proximal tibia angle (intraclass correlation coefficient [ICC] = 0.897 [0.821-0.946]) and the tibial slope measurements (ICC = 0.761 [0.672-0.826]). Conclusions: When optimizing the medial opening-wedge proximal tibial osteotomy, including utilization of a sagittally oriented hinge, placement of a trapezoidal plate posteriorly, and fixation with knee hyperextension, posterior tibial slope can be maintained regardless of the degree of coronal correction. Clinical Relevance: Tibial slope has a significant effect on cruciate ligament stress and a better understanding of coronal plane correction, and its effect on tibial slope is critical when performing proximal tibia osteotomies.