Background:High tibial osteotomy (HTO) aims to realign the varus knee to alleviate stress in the medial compartment. However, detailed information on the impact of HTO on stress distribution across the tibiofemoral joint surface still needs to be completely elucidated.Purpose/Hypothesis:The present study aimed to analyze the subchondral bone density distribution to validate the alignment threshold causing paradoxical changes. We hypothesized that there would be a paradoxical stress change in the medial compartment beyond a specific threshold for lower limb realignment after HTO.Study Design:Case series; Level of evidence, 4.Methods:A retrospective clinical study of 32 knees from 30 patients who underwent medial opening-wedge HTO between 2015 and 2019 was conducted at Hokkaido University Hospital. The subchondral bone density across the tibiofemoral joint was analyzed using computed tomography–osteoabsorptiometry before and after HTO. The high-density area (HDA) within the medial and lateral compartments and their subregions, which were quartered in the coronal plane, was specifically examined.Results:The hip-knee-ankle angle, medial proximal tibial angle (MPTA), joint line obliquity (JLO), and joint line convergence angle significantly changed after HTO ( P < .01). The HDA of the medial compartment to the total HDA ratio decreased from 83% to 77%. Paradoxically, the HDA in the most central subregion of the medial compartment increased from 24% to 30%. There were significant differences between MPTA and JLO in patients with and without paradoxical changes in the HDA. MPTA and JLO cutoff values causing paradoxical changes in the HDA were 94° and 4°, respectively.Conclusion:There was a paradoxical stress increase in the M4 region at the medial compartment associated with the MPTA and JLO beyond specific thresholds. Therefore, surgical planning should be cautiously performed to prevent overcorrection, which can lead to adverse stress distribution changes.

中文翻译：

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高位胫骨截骨术后近端胫骨关节面内侧间室软骨下骨密度的矛盾变化：详细的软骨下骨密度分析


背景：胫骨高位截骨术（HTO）旨在重新调整膝内翻以减轻内侧间室的压力。然而，关于 HTO 对胫股关节表面应力分布影响的详细信息仍有待完全阐明。目的/假设：本研究旨在分析软骨下骨密度分布，以验证导致矛盾变化的对齐阈值。我们假设 HTO 后内侧间室会出现矛盾的应力变化，超出下肢重新对准的特定阈值。研究设计：案例系列；证据级别，4。方法：对 2015 年至 2019 年间接受内侧开口楔形 HTO 的 30 名患者的 32 个膝关节进行回顾性临床研究，在北海道大学医院进行。在 HTO 之前和之后使用计算机断层扫描-骨吸收测量法分析整个胫股关节的软骨下骨密度。专门检查在冠状平面上四等分的内侧和外侧间室及其子区域内的高密度区域（HDA）。结果：髋膝踝角、胫骨近端内侧角（MPTA）、关节线HTO 后倾斜度 (JLO) 和关节线会聚角显着变化 ( P < .01)。内侧室的HDA占总HDA的比例从83%下降到77%。矛盾的是，内侧室最中心分区的 HDA 从 24% 增加到 30%。对于 HDA 有或没有异常变化的患者，MPTA 和 JLO 之间存在显着差异。引起 HDA 矛盾变化的 MPTA 和 JLO 截止值分别为 94° 和 4°。结论：与 MPTA 和 JLO 相关的内侧间室 M4 区域的应力增加超过特定阈值。因此，应谨慎执行手术计划，以防止过度矫正，从而导致不利的应力分布变化。