Should sagittal osteotomy line be parallel to tibial posterior slope in high tibial osteotomy?

Abstract

BackgroundThe reason why the osteotomy line in the sagittal view should be parallel to the medial tibial posterior slope in open wedge high tibial osteotomy (OWHTO) remains unclear. In addition, previous study reported that a posterolateral hinge position led to an increase in tibial posterior slope (TPS) after OWHTO. Our aims were to examine the relationships between angles among the tibial plateau and osteotomy planes or the hinge point and the change in TPS, and the location of the hinge position after OWHTO using three-dimensional computed tomography (3DCT). We hypothesized that the sagittal angle between the tibial plateau and osteotomy planes with an anterior-widening proximal tibial fragment resulted in increased TPS, and the hinge position located posterolaterally.MethodsPreoperative planning anticipated a weight-bearing line ratio of 62% on the radiograph. The anterior gap was 67% of the posterior gap in OWHTO. We identified the tibial plateau and upper and lower osteotomy planes on 3DCT of 82 patients with symptomatic medial osteoarthritic knee after OWHTO. The osteotomy plane angles between the tibial plateau and upper osteotomy planes, and opening gap angles between both osteotomy planes in the coronal and sagittal views were measured. The anteroposterior (AP) and lateral hinge position was displayed as a percentage on the upper osteotomy plane. We assessed the relationships among them.ResultsThe TPS significantly increased after OWHTO (p = 0.002). There was no significant difference between the sagittal osteotomy plane angle and the change in TPS. The sagittal opening gap angle and the AP hinge position ratio were significantly correlated with the change in the TPS (r = 0.477 p < 0.001 and r = − 0.342, p = 0.002, respectively). The hinge position was located a mean of 16.0% from the lateral and 48.6% from the posterior tibial edge in the upper osteotomy plane.ConclusionsContrary to our expectation, the osteotomy plane did not need to be parallel to the tibial plateau plane in the sagittal view. However, the osteotomy gap should be rectangular in the sagittal view. The hinge position located nearly in the center of the sagittal view.

Editorial Commentary: Posterolateral Malposition of the Cortical Hinge During Medial Open-Wedge High Tibial Osteotomy Increases Posterior Tibial Slope: Incomplete Posterior Osteotomy May Shift the Hinge From Lateral to Posterolateral

“…Until now, the sagittal osteotomy line parallel to the slope has been emphasized for minimizing inadvertent changes in the PTS. 6,7 Similar to the results of the study by Akamatsu et al, 8 the finding of this study about the lower effect of the sagittal axis on the PTS suggests that more research is needed.…”

The effect of the sagittal plane osteotomy inclination on the posterior tibial slope in medial open wedge HTO: experimental study with a square column model

“…Akamatsu et al [ 20 ] reported no significant difference between the sagittal osteotomy plane angle and the change in the PTS, whereas anteroposterior hinge position ratio was significantly correlated with the change in the PTS. These results were inconsistent with our findings.…”

Effect of the sagittal osteotomy inclination angle on the posterior tibial slope change in high tibial osteotomy: three-dimensional simulation study

“…In addition, another noteworthy finding was that when the absolute value of the sagittal osteotomy inclination angle was ≥ 10°, the posterior tibial slope changed significantly before and after osteotomy. According to a previous study 34 , the mean sagittal osteotomy plane angle in 3D CT was 6.2° anteriorly, and this angle did not significantly affect the change in the posterior tibial slope. The results of this previous study differed from those of the present study in that there was no significant difference in the posterior tibial slope after osteotomy, although the sagittal osteotomy angle had an anterior inclination.…”