How do lateral hinge and distraction affect three-dimensional rotation in open wedge high tibial osteotomy?

Association between distal tibial rotation and clinical outcomes of medial open-wedge high tibial osteotomy

BACKGROUND

The purpose of this study was to evaluate the association between changes in knee joint geometry after medial open-wedge high tibial osteotomy (MOWHTO) and clinical outcomes.

METHODS

This was a retrospective study of patients who underwent MOWHTO (101 knees) at our hospital between January 2015 and February 2022 and who were followed up for > 2 years. Radiological and functional outcomes were compared between those who were satisfied with surgery (satisfaction group) and patients who were dissatisfied with surgery (dissatisfaction group). Multiple regression analysis was performed to analyze factors affecting the radiological parameters that significantly differed between the two groups.

RESULTS

The average follow up period was 38.0 ± 15.4 months. There were no significant differences regarding demographic characteristics and preoperative radiological parameters between the satisfaction and dissatisfaction groups. There was a significant intergroup difference with respect to postoperative distal tibial rotation and change in distal tibial rotation (13.5 ± 4.8° and 9.5 ± 4.3°, respectively; P < 0.001). The difference in tibial rotation before and after surgery was 4.3 ± 2.3° and 1.7 ± 1.8° in the dissatisfaction and satisfaction groups (P < 0.001) Multiple regression analysis showed that the correction angle affected the distal tibial rotation in MOWHTO (R2 = 0.079, ß = 0.165, P = 0.038).

CONCLUSIONS

In MOWHTO, an increase in distal tibial rotation was associated with patient dissatisfaction. Because the increase in distal tibial rotation is associated with a large correction angle, excessive distal tibial rotation should be avoided when MOWHTO requires a large correction angle.

Effects of different hinge positions on tibial rotation in uniplanar medial opening wedge high tibial osteotomy with three-dimensional tibial models

Background

To investigate the effects of different hinge positions in the sagittal and axial planes on distal tibial rotation (DTR) during medial opening wedge high tibial osteotomy (MOWHTO) with three-dimensional tibial models.

Methods

Preoperative CT data from 30 knee joints in 30 patients who underwent surgery for varus malalignment of knee were included. 1 standard hinge position (0°), 6 axial planes (±5°, ±10°, ±15°), and 6 sagittal planes (±5°, ±10°, ±15°) hinge positions were defined and virtual uniplanar osteotomy was performed. The correction angle of each model was generated using Fujisawa's point. Participants' baseline characteristics, radiologic parameters and DTR were measured. One-Way Repeated Measures ANOVA and single factor linear regression analysis were used to analyze the association between tibial rotation and hinge position in the sagittal and axial planes.

Results

We found a clear linear correlation between changes in hinge position in the sagittal plane and DTR. The changes in DTR were the smallest when the hinge position was at 5°, where internal or external rotation of the DTR may occur. When the front aspect of hinge axis rotated distally, DTR tended towards internal. Meanwhile, when the front aspect of hinge axis rotated proximally, DTR tended towards external. There were no correlations with every hinge axis position in the axial plane.

Conclusions

It is sagittal but not axial hinge axis affects DTR in uniplanar MOWHTO with three-dimensional tibial models. In the sagittal plane, every change in hinge position was significantly linearly correlated with DTR. However, no linear correlations were observed between every hinge position change in the axial plane.

Osseous factors influencing distal tibial rotation in biplane medial opening wedge high tibial osteotomy

PURPOSE

There is a lack of studies investigating the distal tibial rotation (DTR) during medial opening wedge high tibial osteotomy (MOWHTO). This study was designed to evaluate osseous factors influencing DTR in patients who underwent biplane MOWHTO.

METHODS

A total of 106 knee joints in 69 patients who underwent surgery for varus malalignment of knee were reviewed. Based on several software, standard and actual hinge positions were defined in pre-operative and post-operative CT data. Pearson's correlation and Spearman's correlation analysis were performed with DTR change as the dependent variable. Independent variables included angles between standard and actual hinge in the sagittal (ASAHS) and axial (ASAHA) planes, pre-operative and post-operative medial proximal tibial angle, opening width (OW), tuberosity osteotomy angle, flange angle (FA), gap ratio, and hinge fracture.

RESULTS

The distal tibia rotated approximately 0.35° internally. Pearson's and Spearman's correlation analysis showed that DTR change was associated with ASAHS, OW, and FA. Larger OW and FA resulted in higher external rotation angles.

CONCLUSIONS

DTR change was significantly associated with ASAHS, followed by OW and FA rather than ASAHA if only considering osseous factors in biplane MOWHTO. The distal tibia tended to rotate externally when the actual hinge was inclined posteriorly to the standard hinge in the sagittal planes, but rotate externally or internally when the actual hinge was inclined anteriorly.

Reliability of 3D planning and simulations of medial open wedge high tibial osteotomies

Purpose: In medial open-wedge high tibial osteotomy (HTO) hinge axis and osteotomy plane influence the resulting anatomy, but accurate angular quantifications using 3D-planning-simulations are lacking. The objectives of this study were developing a standardized and validated 3D-planning method of an HTO and to perform several simulated realignments to explain unintended anatomy changes. Methods: The cutting direction of the main osteotomy was defined parallel to the medial tibial slope and the hinge axis 1.5 cm distal to the lateral plateau. For interobserver testing, this 3D planning was performed on 13 digital models of human tibiae by two observers. In addition, four different hinge axis positions and five differently inclined osteotomy planes each were simulated. The osteotomy direction ranged from medial 0°-30° anteromedial, while the tilt of the osteotomy plane compared to the tibial plateau was -10° to +10°. All anatomic angular changes were calculated using 3D analysis. Results: Multiple HTO plannings by two medical investigators using standardized procedures showed only minimal differences. In the 3D-simulation, each 10° rotation of the hinge axis resulted in a 1.7° significant increase in slope. Tilting the osteotomy plane by 10° resulted in significant torsional changes of 2°, in addition to minor but significant changes in the medial proximal tibial angle (MPTA). Conclusion: Standardized 3D-planning of the HTO can be performed with high reliability using two-observer planning. 3D-simulations suggest that control of the osteotomy plane is highly relevant to avoid unintended changes in the resulting anatomy, but this can be a helpful tool to modify specific angles in different pathologies in the HTO.