前十字韌帶受損患者上下階梯之生物力學分析

Abstract

前十字韌帶斷裂的發生率在運動參與者的發生率相當高，而導致其膝關節不穩定以及功能受損，因此能夠快速且精確的診斷前十字韌帶斷裂對於患者後續的臨床照護是必要的。本研究利用區段性地分析方式來探討正常人與前十字韌帶缺損膝關節前向鬆弛度檢查的差異，從而訂定出兩個與診斷標準：第二區段位移量大於3.7 mm（公厘），以及第三區段勁度（stiffness）小於22 N/mm（牛頓/公厘），兩標準的診斷精確度並經證實具有良好的敏感度（sensitivity）以及特異性（specificity）。在前十字韌帶缺損患者隨後的復健過程中，詳細監測其各項功能活動能力的恢復，對其是否能回復以往運動活動有重要的決定性。本研究利用臨床平衡運動功能儀的長型力板上的登階-跨越測試（step up and over test）以檢測不同恢復階段患者之功能表現，結果顯示抬升力指標（lift-up index），擺盪跨越時間（time of swing-over），以及擺盪腳落地瞬間的兩下肢承重分配（load-distribution at impact）等三項參數能夠作為鑑別前十字韌帶缺損患者功能缺損的參考。上述兩項研究皆應用生物力學觀點切入常用之臨床檢查，並確認其能提供具良好的檢測敏感度可應用前十字韌帶缺損患者。 完成階梯活動有賴於雙下肢各關節具有足夠的活動度與力量，以及複雜的相互連動。膝關節位於構成下肢之三關節連桿系統的中心位置，與同側肢其他關節以及對側肢關節透過精密地神經肌肉與骨骼系統之聯合控制方能完成各項功能性活動。而在前十字韌帶受損後，膝關節的機構產生了缺損，即可能會讓上述緊密的關係產生改變而造成後續的適應與調整。本研究利用完整的三維運動學與動力學分析探討單側前十字韌帶受損患者於從事階梯活動時下肢的變化與適應策略。外在地面反作用力的分析顯示前十字韌帶患者會採用較慢的步頻及減少患肢承重的保護性策略。在下階梯時，患側肢較健側肢承擔相對較大地面反作用力參數，也顯示與患者對下樓梯感到比較困難有其關聯性。在關節運動學方面，單側前十字韌帶缺損患者主要的改變發生在髖關節，產生較大的屈曲與內收的角度範圍，以及較少的外轉角度，踝關節也顯示出較小的整體活動範圍。在身體穩定性的控制部份，上階梯時，患者的身體質量中心-足底壓力中心連線（center-of-mass-to-center-of-pressure）會有較大的最大後傾角度，以及內外傾角度範圍減小的現象。而在下階梯時，則是後向與內向的傾斜角度皆有明顯下降的情形。而在足部擺盪的控制，則可以觀察到上階梯以健側肢為後腳時，由於沒有視覺回饋的輔助，會保留與階梯間較大的間隙距離，以因應患側為前測支撐腳時可能的不穩定現象。進一步對於關節動力學的深入探討，發現單側前十字韌帶缺損患者會把較大比例的軸向力承擔放在健側肢的每個關節，以減少患側肢關節所需承擔的比例，而更重要的目標，為了達到減少患側膝關節所需承擔的前向力，兩側踝關節的前向力都因應而有顯著地提高的現象。在各關節力矩的表現上，也可以在不論是上或下階梯時的前半段支撐期，觀察到膝伸直肌力矩的顯著下降（亦即「避免股四頭肌作用」之現象），因應而在健側另外兩個關節則會發現明顯的髖關節外展肌與踝關節蹠曲肌力矩的增加。雙下肢各個關節間運動學與動力學的改變會導致彼此間相互地牽動與影響，對於單側前十字韌帶缺損患者在從事階梯活動時的運動學與動力學在本論文中已完成詳細而深入的探討。這些研究結果期能對這類患者在受傷後的適應機制有更完整的了解，而能進一步應用於對這類患者有更適當的訓練計畫設計，以及減少或避免患者爾後產生重複受傷的情形。

The incidences of ACL tears were high in particular sports participations. The injury of the ACL could lead to anterior instability of the knee joint and substantial functional disability. The accurate diagnosis of ACL tear is vital to the following patient care. The regional analysis of the anterior knee laxity was used to show the differences of the anterior knee laxity between the normal and ACL-deficient knees. Two diagnostic criteria were developed based on our results: Region 2 with a displacement larger than 3.7 mm and Region 3 with stiffness smaller than 22 N/mm. They demonstrated good levels of both sensitivity and specificity in distinguishing the ACL-injured knees from possible ACL patients. Careful monitoring of functional recovery was essential for these patients before returning to sport activities. Investigation on stepping up and over test on a clinical forceplate system revealed the alterations in kinetic characteristics in ACL-deficient patients in different recovery phases. The results showed that the lift-up index, the time of swing-over and load-distributing strategy at impact could be important parameters in indentifying functional impairments for patients with ACL deficiency. These studies confirmed that, with a biomechanical approach, two assessments with instruments frequently used in clinics were presented and proved to be sensitive to the impairments in patients after ACL injury. The lower extremity is a three-joint linkage system and stair locomotion is achieved through a complicated interaction of these joints. The knee joint is located in the middle of the linkage system and works sophisticatedly with the complex and interactive neuromusculoskeletal system. Injury of the ACL may change the relationship between these joints and the subsequent adaptations were expected. Three-dimensional kinematic and kinetic analyses of the lower limb joints during stair ascent and descent were performed on the patients with ACL deficiency and compared with the healthy controls. The results showed that these patients would adopt a protective strategy with slower cadences and reduced force-bearing on the affected limb. During stair descent, relatively larger magnitudes of the GRF parameters were also found in the affected limb than in the unaffected limb, which supported the responses in patients with ACL deficiency who would find it more challenging to perform stair descent. The kinematic adaptations during stair locomotion in patients with ACL deficiency were mainly made by the hip joint, with larger flexion and adduction, and less ER angles. A smaller range of motion at the ankle joint was also noticeable. Studies on control of the body stability and foot clearance during stair locomotion showed that the ACL-deficient patients demonstrated the increased posterior body center-of-mass-to-center-of-pressure (COM-COP) inclination and reduced medial COM-COP inclination during stair ascent. However, the ACL-deficient patients would reduce the body inclinations in both posterior and medial directions during stair descent. During stair ascent, the increased foot clearances in the trailing legs were demonstrated in the unaffected limbs, suggesting that because of the unstable stance leg, these patients may have to preserve a larger spacing from the obstacle under the condition without visual assistances. Further investigation on the kinetic alterations confirmed that ACL-deficient patients tended to leave a larger proportion of loadings on the three joints of the unaffected limbs and try to reduce those on the affected limb during stair locomotion. The anterior forces transmitted at the affected knees were found reduced significantly during stair ascent and descent. In response, the increased anterior forces were demonstrated at the ankles in both the affected and unaffected limbs. The reduced extensor moments were demonstrated at the affected knees in the early stance phase of stair ascent and descent. The corresponding adaptations occurred mainly in the hip and ankle joints of the unaffected limbs with increased hip abductor and ankle plantarflexor moments. Knowledge of the kinematics and kinetics of stair locomotion in the healthy young subjects and in patients with unilateral ACL deficiency were established. These investigations provided the insight in the adaptations during stair locomotion in the patients with unilateral deficiency, and could be used further in designing training programs or developing prevention strategies to avoid repeated injuries in the patients with unilateral ACL deficiency.