2021 ISAKOS Biennial Congress ePoster
Tibial Slope Can Be Maintained During Medial Opening Wedge Proximal Tibial Osteotomy
Joseph J. Ruzbarsky, MD, Aspen, CO UNITED STATES
Justin W. Arner, MD, Pittsburgh, PA UNITED STATES
Grant J Dornan, MS, Vail, CO UNITED STATES
Matthew T. Provencher, MD, Vail, CO UNITED STATES
Armando F. Vidal, MD, Vail, CO UNITED STATES
Steadman-Philippon Research Institute, Vail, Colorado, UNITED STATES
FDA Status Cleared
Summary
When optimizing the medial opening wedge proximal tibial osteotomy, including utilizing a lateral hinge, placement of a trapezoidal plate posteriorly, and fixation with forced knee extension, posterior tibial slope can be maintained regardless of the degree of coronal correction.
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Abstract
Background
Tibial slope and its effect on cruciate ligament strain is increasingly appreciated. A prior systematic review demonstrated that medial opening wedge proximal tibia osteotomies have a tendency to increase the posterior tibial slope by 2 degrees.
Methods
Proximal tibia osteotomies were performed on 10 fresh frozen cadaveric knees using a commercially available guide to generate a medial opening wedge osteotomy with a purely lateral hinge. Coronal plane correction was performed using both 5mm and 10mm trapezoidal wedged osteotomy plates. Techniques that maximized the posterior to anterior gap ratio were done to minimize the effect on tibial slope. These included posterior plate placement, a trapezoidal, sloped plate, and forced knee extension during plate fixation to help close the anterior gap. Anterior and posterior gap widths were measured during each state. Medial proximal tibia angle and posterior tibial slope were measured pre-osteotomy and after both 5mm and 10mm wedged implants using anteroposterior and lateral standard fluoroscopic images. Three independent observers performed all radiographic measurements and intraclass correlation coefficients were calculated.
Results
The 5mm and 10mm trapezoidal wedged osteotomy plates increased the medial proximal tibia angle by a mean of 3.5 and 7 degrees, respectively. The 5mm and 10mm trapezoidal wedged osteotomy plates decreased the posterior tibial slope by a mean of 1.0 and 0.6 degrees, respectively. The mean gap ratio percentage of the 5mm and 10mm trapezoidal wedged osteotomy plates was 67% and 70%, respectively. Good intraobserver reliability was found for both the medial proximal tibia angle (ICC = 0.897, [0.821-0.946]) and the tibial slope measurements (ICC = 0.761,[0.672-0.826]).
Conclusions
Contrary to prior evidence, medial opening wedge proximal tibia osteotomies can maintain tibial slope irrespective of coronal correction by utilizing a lateral hinge, placing a trapezoidal plate posteriorly, and fixation during forced knee extension. With careful consideration of the importance of tibial slope, medial opening wedge proximal tibia osteotomies do not increase posterior slope.