Morphologic and Kinematic Adaptations of the Subtalar Joint after Ankle Fusion Surgery in Patients with Varus-type Ankle Osteoarthritis

项目总结 胫距关节融合术，或称“踝关节融合术”，是治疗创伤后踝关节的黄金标准手术。 骨性关节炎(OA)。踝关节融合术带来了疼痛的缓解，至少在短期内是这样；然而，在 胫距关节对距下关节提出了新的要求，可能会超过软骨的极限和结果。 在二次骨关节炎中。大多数接受踝关节融合术的患者在术前都有关节的排列畸形。 胫距和距下关节。值得注意的是，60%的踝关节骨性关节炎患者有内翻畸形。 胫距关节。最近发现，同侧距下关节为代偿性外翻。 大约一半的内翻型踝关节骨性关节炎患者接受了治疗。对侧内翻外翻畸形 倾向于中和腿和后脚的整体对齐，使其在大体临床上看起来是正常的 检查。不幸的是，尽管目前的踝关节融合术建议为 如何矫正胫距关节内翻不齐，对代偿性外翻没有规定 距下关节对齐。我们最近完成的R21项目的结果说明了外科医生的潜力 策略性地调整踝关节融合术以控制术后的活动、关节间隙距离和一致性 距下关节，可转而调节继发性骨性关节炎。尽管如此，踝关节融合手术的具体效果 对距下关节的形态和功能的影响尚未在体内进行纵向评价。我们的总体目标是 确定导致踝关节融合术后患者预后较差的机械和结构因素。R01 本文建议通过对脚踝的影响进行定量的、纵向的描述来实现这一目标 体内融合手术对距下关节形态和功能的影响。在这里，我们以一种聚焦的、机械化的方式 在踝关节内翻的患者中，被细分为两个相等的组(有和没有代偿性外翻 距下关节对齐；每组24人)。根据我们的初步数据，我们假设患者 术前距下关节的代偿性对齐有更大的风险经历形态改变- 踝关节融合术后24个月的功能关系和不良结局。目标1将量化如何 踝关节融合从纵向统计形态改变距下关节的排列和形态 由负重计算机断层扫描构建的模型。目标2将量化脚踝融合 使用DUAL在行走、楼梯上升和楼梯下降过程中更改距下关节的活体运动学 透视检查。AIM 3将综合这些数据，以确定和隔离距下关节的术前对齐 关节对距下关节的形态、活体运动和患者预后有影响。如果成功，该项目将提供 第一次也是唯一一次对踝关节融合术效果的机械性理解。我们期待着这些工作完成 AIMS还将为我们未来进行干预性研究提供先决条件信息，在那里我们将 评估在手术时计入外翻补偿是否会产生更好的结果。

PROJECT SUMMARY Tibiotalar arthrodesis, or ‘ankle fusion’, is the gold standard surgical treatment for posttraumatic ankle osteoarthritis (OA). Ankle fusion brings pain relief, at least in the short term; however, elimination of motion at the tibiotalar joint imposes new demands at the subtalar joint, which may exceed the limit of cartilage and result in secondary OA. Most patients undergoing ankle fusion surgery have preoperative deformities in the alignment of the tibiotalar and subtalar joints. Notably, 60% of all patients with ankle OA have varus malalignment of the tibiotalar joint. Recently, it was discovered that the ipsilateral subtalar joint adopts ‘compensatory’ valgus alignment in approximately half of those patients with varus-type ankle OA. Opposing varus-valgus deformities tend to neutralize the overall alignment of the leg and hindfoot, making it appear normal on gross clinical inspection. Unfortunately, while current surgical recommendations for ankle fusion provide clear guidance for how to correct varus malalignment of the tibiotalar joint, they make no stipulation for compensatory valgus alignment of subtalar joint. Results from our recently completed R21 project illustrate the potential for surgeons to strategically align the ankle fusion to control for postoperative motion, joint space distance, and congruency of the subtalar joint, which could in turn mediate secondary OA. Still, the specific effects of ankle fusion surgery on the form and function of the subtalar joint have not been evaluated longitudinally in-vivo. Our broad goal is to identify mechanical and structural factors that lead to inferior patient outcomes after ankle fusion. The R01 proposed herein addresses this goal through quantitative, longitudinal characterization of the effects of ankle fusion surgery on the form and function of the subtalar joint in-vivo. Here, we take a focused, mechanistic look at patients with varus ankle OA that are subdivided into two equal groups (with and without compensatory valgus alignment of the subtalar joint; n = 24 per group). Guided by our preliminary data, we hypothesize that patients with preoperative compensatory alignment of the subtalar joint are at greater risk of experiencing altered form- function relationships and inferior outcomes at 24 months post ankle fusion surgery. Aim 1 will quantify how ankle fusion changes the alignment and morphology of the subtalar joint from longitudinal statistical shape models constructed from weight-bearing computed tomography scans. Aim 2 will quantify how ankle fusion changes the in vivo kinematics of the subtalar joint during walking, stair ascent, and stair descent using dual fluoroscopy. Aim 3 will synthesize these data to identify and isolate the role preoperative alignment of the subtalar joint has on subtalar joint morphology, in vivo motion, and patient outcomes. If successful, this project will provide the first and only mechanistic understanding of the effects of ankle fusion. We anticipate that completion of these aims will also provide prerequisite information for us to pursue a future interventional study, where we would evaluate whether accounting for valgus compensation at the time of surgery yields better outcomes.