A New Preoperative Planning Technique Can Reduce Radiation Exposure During the Performance of Medial Opening-Wedge High Tibial Osteotomy

Clinical outcomes of guider-assisted osteotomy compared to conventional pendulum-saw osteotomy in open wedge high tibial osteotomy: a propensity score-matched cohort study

PURPOSE

We developed a novel guider-assisted osteotomy (GAO) procedure to improve the safety of open wedge high tibial osteotomy (OWHTO) and aimed to compare its efficacy and complications with the conventional pendulum-saw osteotomy (PSO).

METHODS

This is a retrospective cohort study of patients undergoing either GAO or PSO procedure in the OWHTO to treat varus knee osteoarthritis, who had a minimum of 2 years of follow-up. Patients were propensity score matched (PSM) in a 1:1 ratio based on demographic and clinical data with a caliper width of 0.02. The outcomes assessed involved the hospital for special surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and the Intraoperative and postoperative complications.

RESULTS

199 patients were included in each group after PSM. The mean duration of follow-up was 38.3 ± 8.9 months. The GAO group had a shorter operation duration (104.5 ± 35.7 vs. 112.1 ± 36.0 min, p = 0.027) and fewer times of intraoperative fluoroscopy (4.2 ± 1.4 vs. 6.0 ± 1.4, p < 0.001). At the last follow-up, clinical scores for knee achieved significant improvements in both GAO and PSO groups: HSS (67.5 ± 10.5 vs. 90.2 ± 7.0, p < 0.001; 69.4 ± 8.2 vs. 91.7 ± 6.8, p < 0.001) and WOMAC (65.7 ± 11.6 vs. 25.2 ± 10.4, p < 0.001; 63.3 ± 12.2 vs. 23.8 ± 9.5, p < 0.001). However, no significant difference was observed between groups for any measures (p > 0.05). In addition, the intraoperative complications (0.5% vs. 3.5%, p = 0.068) and the postoperative bone delayed union and nonunion (1.0% vs. 4.5%, p = 0.032) were marginally or significantly reduced in the GAO versus PSO group.

CONCLUSION

GAO demonstrates improvements in intraoperative radiation exposure and complications, with comparable short-term efficacy to PSO, and could be considered a viable alternative in clinical practice.

HKA Angle-A Reliable Planning Parameter for High Tibial Osteotomy: A Theoretical Analysis Using Standing Whole-Leg Radiographs

High tibial osteotomy (HTO) is a recognized treatment for early-stage medial compartment knee osteoarthritis. Preoperative planning with standing whole-leg radiographs (WLRs) is essential for ensuring optimal postoperative alignment. The primary purpose of this study is to investigate the theoretical accuracy of the wedge opening required for two different preoperative planning parameters in open-wedge HTO. The second purpose is to theoretically determine which parameter is superior. Preoperative planning for HTO was performed with standing WLRs for 39 knees with isolated medial osteoarthritis. The Miniaci preoperative planning method was applied to correct the hip-knee-ankle (HKA) angle to 3to 6 degrees of valgus and the weight-bearing line (WBL) percentage within 60 to 70% of the width of the tibial plateau. To ensure that the HKA angle was between 3 and 6 degrees of valgus, the required accuracy window for the Miniaci angle was 3.25 ± 0.03 degrees (range, 3.20-3.30°). To ensure that the WBL percentage was between 60 and 70%, the accuracy window required for the Miniaci angle was 2.35 ± 0.13 degrees (range, 2.10-2.65°). This study suggests that to correct the HKA angle and the WBL percentage within the target range on two-dimensional WLRs, the Miniaci angle must be controlled to an accuracy of ± 1.63 and ± 1.18 degrees, respectively. Theoretically, the HKA angle is highly suitable as a preoperative planning parameter for HTO with a large permissible error and a small variability in the degree of change in the Miniaci angle (ΔMiniaci).

How do osteotomy and distraction affect distraction angles of opening wedge high tibial osteotomy?

BACKGROUNDS

Trigonometric formulae have been derived to correlate the distraction angle (height) and tibial specifications. However, the assumption-induced simplifications are inherent in the formulae such as the rigid tibia and the specific orientations of cutting plane and lateral hinge. This study aimed to evaluated the accuracy of the trigonometric formulae.

METHODS

The 3D printed tibiae were used as the specimens for which the hinge orientations and distraction sites were systematically varied. Hinge orientation was determined by wedge inclination of the bone saw into the medial tibia and saw progression near the lateral cortex. The specimens were distracted at different distraction sites to measure the distraction angles that were compared with literature formulae.

FINDINGS

In cases of the same distraction height, the wedge inclination, saw progression, and distraction site had various impacts on the coronal angles, indicating that the ideal formula should consider these parameters. Averagely, the predicted angles of the literature formulae were 15% higher than the testing results. The differences in these results may be attributed to the deformable property of the specimen material, non-ideal hinge orientation, and differences in distraction sites. Saw progression and distraction site had greater impacts than wedge inclination on the distraction angle.

INTERPRETATION

Variations in three surgical indices constitute a complicated mechanism that affects the 3D hinged rotation of the distracted plateau. The non-middle distraction further deforms the tibial rotation and reduces the accuracy of the trigonometric formulae. The trigonometric formulae might underestimate the distraction angle; thus. Appropriate corrections are necessary for clinical application.