Qordja Fjorela, Valpiana Pieralberto, Andriollo Luca, Rossi Stefano Marco Paolo, Salvi Andrea Giordano, Bocchino Guido, Zepeda Karlos, Benazzo Francesco, Indelli Pier Francesco
Department of Clinical and Molecular Sciences, Clinic of Orthopaedics Università Politecnica delle Marche Ancona Italy.
Südtiroler Sanitätsbetrieb Brixen Italy.
J Exp Orthop. 2025 Jul 18;12(3):e70370. doi: 10.1002/jeo2.70370. eCollection 2025 Jul.
New alignment classifications based on phenotype reproduction have recently been introduced in total knee arthroplasty (TKA) as alternatives to traditional mechanical alignment. These classifications were designed according to the static hip-knee-ankle angle (sHKA) measurement from long leg radiographs (LLRs). This study aimed to understand whether and how the HKA varied throughout the knee's range of motion (ROM) during robot-assisted TKA.
This prospective, bi-centric cohort study involved 107 consecutive patients undergoing primary robot-assisted TKA. The surgical technique adhered to restricted kinematic alignment (HKA ± 3°) with asymmetric gap balancing principles. The HKA's dynamic variation (dHKA) was assessed intraoperatively at full extension, as well as at 30°, 45°, 60°, 90° and 120°, both before bone cuts and after the positioning of the trial components. The overall cohort was initially analyzed, followed by a subgroup analysis based on varus, neutral and valgus phenotypes. A descriptive analysis was conducted to evaluate dHKA trends. Collected data were then analyzed using one-way repeated measures analysis of variance with Bonferroni correction and Bland-Altman plots to assess significant variations in dHKA across the ROM during flexion and to quantify outliers from the established safe boundaries of ±3°.
Out of 107 knees, the pre-cut dHKA demonstrated a biphasic trend, decreasing in varus until 60° and then transitioning toward valgus, with significant differences primarily noted at 90° and 120°. Post-cut, the dHKA exhibited an overall varus trend, increasing from full extension to 60° before experiencing a partial recovery. Significant differences were detected primarily at the initial flexion angles. Outlier rates increased with flexion: pre-cut from 6.5% to 43.0%, and post-cut from 1.9% to 30.8%, highlighting progressive inter-individual variability throughout. Although the analysis was stratified by knee phenotype, the post-cut dHKA trend did not differ among the various phenotypes or in comparison to the overall cohort trend.
The main finding of the current study was that intraoperative dHKA differs significantly from sHKA during robot-assisted TKA. Moreover, the sHKA was limited in predicting the actual kinematic HKA. Planning the final TKA alignment on static, standing LLRs may have limited value compared to intraoperative planning conducted with enabling technologies.
Level 3.
基于表型再现的新对线分类法最近在全膝关节置换术（TKA）中被引入，作为传统机械对线的替代方法。这些分类法是根据长腿X线片（LLR）测量的静态髋-膝-踝角（sHKA）设计的。本研究旨在了解在机器人辅助TKA过程中，HKA在膝关节活动范围（ROM）内是否以及如何变化。
这项前瞻性、双中心队列研究纳入了107例连续接受初次机器人辅助TKA的患者。手术技术遵循受限运动学对线（HKA±3°）和不对称间隙平衡原则。在全伸直位以及在截骨前和试模组件定位后，分别在30°、45°、60°、90°和120°时术中评估HKA动态变化（dHKA）。首先对整个队列进行分析，然后根据内翻、中立和外翻表型进行亚组分析。进行描述性分析以评估dHKA趋势。然后使用单因素重复测量方差分析并进行Bonferroni校正以及Bland-Altman图分析收集的数据，以评估屈曲过程中ROM内dHKA的显著变化，并量化超出既定±3°安全边界的异常值。
在107个膝关节中，截骨前dHKA呈现双相趋势，在内翻时直至60°减小，然后转变为外翻，主要在90°和120°时存在显著差异。截骨后，dHKA总体呈现内翻趋势，从全伸直位增加至60°，然后部分恢复。主要在初始屈曲角度检测到显著差异。异常值发生率随屈曲增加：截骨前从6.5%增至43.0%，截骨后从1.9%增至30.8%，突出显示了整个过程中个体间变异性的增加。尽管分析按膝关节表型分层，但截骨后dHKA趋势在不同表型之间或与整个队列趋势相比并无差异。
本研究的主要发现是，在机器人辅助TKA过程中，术中dHKA与sHKA存在显著差异。此外-sHKA在预测实际运动学HKA方面存在局限性。与使用现有技术进行的术中规划相比，基于静态站立LLR规划最终TKA对线可能价值有限。
3级。
