利用機械手臂關節測試系統研究距下關節骨融合術對踝關節穩定度與外側韌帶之影響

Abstract

踝關節在人體的各種功能性動作中扮演著極重要的角色，而足踝損傷經常伴隨著韌帶傷害，長期處於不穩定的情況下，容易引發創傷性踝關節炎，通常選擇全人工踝關節替換或骨融合手術來減輕疼痛。過去在踝關節相關研究中，多以自行開發之多自由度關節測試儀器來量化穩定度，並評估軟組織在關節活動中之貢獻，手法因人而異，造成各家結論不一的情況。少有研究將機械手臂關節測試系統應用在踝關節，是因受限於無法控制距骨之移動，而本實驗的目的，是利用骨融合手術時將距下關節鎖住，進而達到機械手臂同時控制距腓骨聯合與跟骨、距骨的目的，除了探討骨融合前後關節穩定度的改變，骨融合後，便可將外側韌帶對踝關節的影響獨立出來討論。 本研究利用機械手臂關節測試系統，以模擬兩種理學檢查之控制方法(最大力量100牛頓之前拉測試、最大力矩4000牛頓毫米之距骨傾斜測試)，分別對距下關節骨融合前後之三組踝關節試體進行不同屈曲角度下(背屈10度、5度、中性位置、蹠屈5度、10度)之拉伸測試，將所得之關節運動學與力動學資訊結合，比較融合前後關節鬆弛度的變化，並以機械手臂重複運動路徑的功能，在骨融合後排除距骨移動影響，依序剪斷外側韌帶，應用力學疊加原理來量化韌帶的貢獻。關節位移鬆弛度在骨融合後，向前方向平均下降約12%，向後方向5%，旋轉鬆弛度內翻方向平均下降約15%，外翻方向22%。前距腓韌帶主要貢獻在於限制關節前移，蹠屈角度越大，作用越明顯；跟腓韌帶則限制踝關節的內翻運動，隨著背屈角度增加，跟腓韌帶的受力矩也呈現遞增狀況；而後距腓韌帶對於踝關節的運動限制並不明顯，但因幾合位置的關係，與前距腓韌帶一前一後維持關節的穩定性。距骨給予踝關節更大的自由度，在骨融合後損失部分自由度的情況下，依然要達到與手術前正常踝關節的運動行為，勢必將由脛距關節與周圍的軟組織來分擔，除了提高受傷風險外，亦會造成鄰近關節面的過度磨損，而衍生新的關節炎。

The ankle joint plays a very important role in various functional movements of the human body. The lateral ligament damage often associated with ankle injury and it is easy to cause traumatic arthritis. It may bring the neighboring joints arthritis risk when selecting the total ankle replacement or fusion surgery to alleviate the pain. In the previous studies, multiple degrees of freedom arthrometer were used to quantify laxity and assess contribution of soft tissues in joint activities. Talus motion controlling makes rare robotic-based joint testing system (RJTS) used in the studies of the ankle joint. In this study, we used RJTS to control joint motion by anterior drawer test and talar tilt test in different flexion angles on 3 ankle specimens before and after subtalar arthrodesis, then combined joint kinematic and kinetic data to compare the difference of laxity. After excluding the influence of talus moving, we can get ligament contribution by repeating path function of RJTS and superposition theory. After subtalar arthrodesis, joint became more stable. On the other hand, the DOF of ankle joint was lower. It affected varus/valgus rotation more than anterior/posterior displacement. The contribution of ATFL is limiting anterior displacement, the effect is more obvious when plantar flexion angle increases. With dorsiflexion angle increases, CFL restricted varus motion more that the moment became larger. Effect on joint motion of PTFL was less but it maintained joint stable with ATFL because of the shape and position. To achieve the normal ankle motion behavior, it must share the force which came from fixing talus with tibiotalar joints and surrounding soft tissues after subtalar arthrodesis. In addition to increasing the risk of injury, but also resulting in excessive wear of the articular surface of adjacent joint, and deriving arthritis.