Wenning M, Lange T, Paul J, Gollhofer A, Gehring D
Department of Sport and Sport Science, University of Freiburg, Schwarzwaldstr. 175, 79117 Freiburg, Germany; Department of Orthopedic and Trauma Surgery, University Medical Center, Medical Faculty, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany.
Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Kilianstr. 5a, 79106 Freiburg, Germany.
Clin Biomech (Bristol). 2019 Dec;70:107-114. doi: 10.1016/j.clinbiomech.2019.07.033. Epub 2019 Aug 8.
Quantitative measurement of the mechanical deficit in chronic ankle instability (CAI) is difficult. Therefore, the distinction between functional (FAI) and mechanical ankle instability (MAI) as well as the evaluation of surgical techniques is difficult. This pilot study uses a novel method of functional 3-dimensional stress ankle-MRI to test its applicability for assessing mechanical ankle instability.
We used a custom-built ankle arthrometer that allows a stepless positioning of the foot and an axial in situ loading with up to 500 N combined with a 3-dimensional MRI protocol. We assessed four parameters (3D cartilage contact area (CCA) fibulotalar, tibiotalar horizontal and vertical and intermalleolar distance) under six different conditions (neutral-null, plantarflexion-supination and dorsiflexion-pronation each with and without loading) in n = 10 individuals (7 suffering from MAI and 3 healthy controls).
The MAI group showed a substantially increased reduction of lateral osseous constraint compared to healthy controls when the foot was positioned in plantarflexion-supination (CCA fibulotalar 69% vs. 30% in controls). The reduction of the weight bearing surface in plantarflexion-supination was also more pronounced (CCA tibiotalar horizontal -49% in MAI vs. -28% in controls).
This novel technique is valuable for assessing mechanical ankle instability in the target population and has a potential clinical benefit for assessing the mechanical deficit of individual patients. Further studies are needed to provide evidence for a possible prognostic value of this novel technique.
慢性踝关节不稳（CAI）的力学缺陷定量测量较为困难。因此，区分功能性踝关节不稳（FAI）和机械性踝关节不稳（MAI）以及评估手术技术都很困难。这项初步研究采用一种新型的功能性三维应力踝关节磁共振成像方法来测试其在评估机械性踝关节不稳方面的适用性。
我们使用了一种定制的踝关节关节测量仪，它能够对足部进行无级定位，并结合三维磁共振成像协议进行高达500 N的轴向原位加载。我们在n = 10名个体（7名患有MAI，3名健康对照）中，在六种不同条件下（中立位 - 零位、跖屈 - 内旋和背屈 - 外旋，每种情况均有加载和无加载）评估了四个参数（三维软骨接触面积（CCA）腓距、胫距水平和垂直以及内踝间距）。
与健康对照相比，当足部处于跖屈 - 内旋位时，MAI组外侧骨约束的减少显著增加（腓距CCA：MAI组为69%，对照组为30%）。跖屈 - 内旋位时负重面的减少也更为明显（胫距水平CCA：MAI组为 - 49%，对照组为 - 28%）。
这种新技术对于评估目标人群的机械性踝关节不稳具有重要价值，并且在评估个体患者的力学缺陷方面具有潜在的临床益处。需要进一步研究来为这项新技术可能的预后价值提供证据。
