2025 ISAKOS Biennial Congress ePoster
Changes in Talus CT Values Before and After Medial Opening Wedge High Tibial Osteotomy for Knee Osteoarthritis
Yoshiharu Shimozono, MD, PhD, Kyoto City, Kyoto JAPAN
Yuki Shinya, MD, Kyoto JAPAN
Sayako Sakai, MD, Kyoto-Shi JAPAN
Shinichi Kuriyama, MD, PhD, Kyoto, Kyoto JAPAN
Shuichi Matsuda, MD, PhD, Kyoto JAPAN
Kyoto University, Kyoto, Kyoto, JAPAN
FDA Status Not Applicable
Summary
OWHTO results in significant changes in CT values of the talar subchondral bone, particularly on the medial side.
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Abstract
Background
Medial opening wedge high tibial osteotomy (OWHTO) alters knee alignment and changes the lower extremity loading axis. The effects of this change on the ankle joint have rarely been reported. This study aimed to assess the impact of OWHTO on subchondral bone CT values of the talus in patients with knee osteoarthritis (OA).
Methods
Forty-nine patients with knee OA (mean age 61.5±7.2 years; 19 males, 30 females; BMI 27.9±4.7) who underwent OWHTO were included. CT scans of the knee and ankle joints were performed preoperatively and one year postoperatively. The hip-knee-ankle (HKA) angle was measured before and after surgery. In the coronal plane of the talus, CT values were measured using a 12 mm² circle directly under the subchondral bone plate at six locations from medial to lateral (zones 1 to 6) in the central anterior and posterior parts of the talar articular surface.
Results
The mean preoperative HKA angle was 173.5 °±3.5 °, which changed to 181.8±2.4 ° postoperatively. Zone 1 showed a significant decrease in CT values from 744.8 preoperatively to 690.0 postoperatively (p<0.001). Zones 2 to 5 did not exhibit significant changes (zone 2: 635.8→622.7, zone 3: 580.9→589.0, zone 4: 585.1→590.8, zone 5: 612.8→604.9). However, zone 6 demonstrated a significant reduction from 634.6 preoperatively to 608.8 postoperatively (p<0.001). In zone 1, a positive correlation was identified between the preoperative HKA angle and changes in the CT values (r=0.34, p=0.02). There was no significant correlation between the amount of HKA angle correction and changes in CT values.
Discussion
These findings suggest that knee malalignment affects the load distribution across the ankle joint, leading to changes in talar subchondral bone density. The improvement in the HKA angle after OWHTO appears to decrease CT values, notably on the medial side of the talus, indicating a redistribution of load towards a more balanced state. Additionally, patients with greater preoperative varus alignment showed more substantial changes in medial talar CT values, suggesting that the severity of preoperative knee alignment may influence postoperative outcomes in talar subchondral bone density.
Conclusion
OWHTO results in significant changes in CT values of the talar subchondral bone, particularly on the medial side. This study highlights the potential of OWHTO in altering the load distribution in the ankle joint. Further research is warranted to explore the long-term effects of these findings on joint health and function.