踝關節運動力學之幾何特性

Kinematics of the Ankle Joint: Geometric Characteristics

踝關節運動力學之研究與足踝受傷之機轉與治療之原理存有密切的關係，我們利用截肢之踝關節標本，首先使用二維Ｘ光影像，觀察踝關節運動時脛骨與距骨上標定記號之空間位移，再利用三軸定位掃瞄機掃瞄踝關節的接合界面座標，用以建立踝關的曲面函數及接合界面曲率分佈圖。而從兩項實驗結果比對，我們可以看出踝關節的運動模式與接合面曲率匹配有很大的關係。當踝關節完全背屈時，接觸面積偏向前緣及外側，在蹠屈過程中接觸面積也會傾向外側，而此接觸點之實驗結果重複性良好。研究結果顯示，踝關節在完全背屈或蹠屈時，雖然接觸面機會減小，但是關節界面的匹配度也相對增加。

Understanding of the kinematics of the ankle joint would help elucidate the mechanisms of ankle trauma and improve clinical treatment. In this in vitro study, two-dimensional a X-ray was used to observe the displacement of surface markers on amputated ankle joints of human cadavers during passive motion Pressure-sensitive films were inserted into the ankle joint to define the location and area of contact at various ranges of motion. Then, the articular surfaces were measured with a three-dimensional optical scanning system. Surface raw data were fitted with a bivariate parametric function to construct surface curvature maps. Comparisons of the analytical and experimental data showed the kinematics of the ankle joint correlate strongly with the joint surface curvature. As the ankle flexed dorsally, the contact areas of the joint shifted laterally, highlighting the importance of the lateral malleolus in ankle stability. The ankle joint contact area decreased slightly at extreme dorsiflexion and plantar flexion; however, the congruency increased to compensate for the difference. This might be one of the reasons why spontaneous osteoarthritis is not common at the ankle joint.