結合動作分析及動態X光量測技術研究活體人工膝關節之生物力學(2/2)

退化性關節炎病人接受全人工膝 關節置換手術後，如何恢復其日常動 作的功能，以提高其生活品質，是現 階段新型全人工膝關節設計一個相當 重要的課題。以往由於道德上的考量 以及技術上的限制，直接量取人工膝 關節移動時相對的角度及兩元件接觸 點的位置有其困難，因此本研究旨在 發展一個整合動態X 光攝影系統、動 作分析系統、測力板以及數學模型分 析的新技術以探討活體人工膝關節之 生物力學，進而提供人工膝關節在從 事單關節運動與功能性運動時，更精 確與更好之運動學與動力學描述。由 於本研究之受試者兩膝分別植入後十 字韌帶置換(posterior cruciate substituting, PS)型與後十字韌帶保留 (posterior cruciate retaining, CR)型之人 工膝關節，故可避免受試者間各項變 數干擾研究結果。提供了一個探討解 釋這兩種不同類型之膝關節設計的絕 佳機會，對於瞭解後十字韌帶對於人 工膝關節之功能有所幫助。本計畫共 分二階段進行。 第一階段(年)包含建立一個整合 動態X 光攝影系統以及動作分析儀器 設備包括紅外線攝影機、測力板以及 肌電圖等，用以量測完整運動學與動 力學資料的系統。實驗記錄同時植入 PS 型與與CR 型人工膝關節之病人進 行之主動、被動單關節動作及功能性 動作包括步行、做到站等之過程。利 用實驗資料進行下肢生物力學分析， 並特別著重於脛骨股骨關節之力學交 互作用。 第二階段(年)旨在發展一個新的 利用電腦模型與動態X 光資料評估三 維人工膝關節運動學之最佳化方法。 此一新方法將與兩種文獻中既有的方 法比較，透過電腦模擬與驗証實驗， 評估三者的精度與信度。 藉由驗證實驗的結果證實，本研 究結果相當精確。目前本研究所提出 的量測方法是唯一能在非侵入的狀況 下，不受皮膚移動誤差影響而精確測 得人工膝關節患者動態關節三維運動 學及力學的方法。 經過臨床實驗後，透過人工膝關 節患者主動運動、被動運動及功能性 動作之測試了解到人工膝關節患者與 正常人膝關節確有不同的運動學行 為，導致膝關節力學模式跟著改變， 即使保留了後十字韌帶的患者也因其 無法發揮韌帶的正常功能，導致膝關 節運動受限，影響到人工膝關節的受 力狀況。 本計畫全部依據既定時程完成一 個新的三維全人工膝關節量測技術， 並將之應用到全人工膝關節元件相對 運動的測量，所得結果與文獻及全人 工膝關節動作分析實驗數據均相當一 致。本年度計畫成果除有助了解膝關 節運動時韌帶受力及各種不同的擷抗 作用情形，臨床上能幫助置換人工膝關節時更多的資料與改進之處。Total knee arthroplasty has been the main choice of treatment for advanced degenerative knee osteoarthritis over the last few decades. It is essential to provide full functional performances to patients on total knee replacement (TKR) design. Due to ethical considerations and technical limitation, direct measurement of angles during motion and contact points of two components in the Total knee is difficult. The main purposes of the project are to develop a new technique that integrates video-fluoroscopy systems, motion analysis systems, forceplates and electromyography (EMG), as well as mathematical modeling and analysis for in vivo study of total knee biomechanics, providing more accurate and better descriptions of the TKR kinematics and kinetics during isolated joint movement and functional activities. Subjects with PS (posterior cruciate substituting) type TKR in one leg and CR (posterior cruciate retaining) type in another in the present study offer an exceptional opportunity for study of these two different types of knee designs without inter-subject variations, which is helpful for the clarification of the function of posterior cruciate ligament (PCL) in TKR’s. This project will be carried out in two parts (years). In the first part (year) of the project, a complete kinematic and kinetic measurement system integrating a video-fluoroscopy system and motion analysis equipments, namely infrared cameras, forceplates and EMG, was established. Patients with both PS and CR type TKR’s performed passive and active isolated joint movements and functional activities including gait and sit-to-stand while kinematic and kinetic data were measured. Kinematic and kinetic analysis of the lower limb with special attention on the interaction of the tibiofemoral was performed. In the second part, a new optimization method for model-based estimation of the three-dimensional kinematics of TKR using dynamic fluoroscopic data was developed. Comparisons of the accuracy and reliability of the new method with two existing methods was performed based on computer simulations and experimental data. Present study proposed a new technique for improving the accuracy of 3D pose estimation and accelerate computational process without manual operation. All 2D real data and projection silhouettes are warped to stick on 3D spherical surface before the matching process. Therefore, template matching based on shape invariant can be applied for perspective projection system and can divide 6 degrees of freedom (DOF) of model to calculate respectively. The results from the current study showed that the majority of patients experienced kinematics is not similar to those of a normal knee. However, the extent of lateral femoral condyle posterior rollback and the extent of axial rotation were less

A 3D computer graphics-based biomechanical model of the knee joint for the design and evaluation of total knee replacements (2/3)

人工全膝關節置換手術(total knee replacement;ＴKR)一直是治療退化性膝關節 炎的主要選擇。除了持續加強人工全膝關節 本身耐磨耗性與固定外，如何恢復病人術後 日常動作的功能，以提高其生活品質，是現 階段新型人工全膝關節設計一個相當重要的 課題。 本（第二）年度計畫旨在利用第一年建 立之電腦模型進行手術模擬，探討不同人工 關節設計（後十字韌帶保留型、替代型）對 膝關節力學與動作功能之影嚮。 本研究結果顯示，人工全膝關節置換 後，膝關節的穩定度明顯下降，因為韌帶及 關節面等被動受力結構被去除或改變，而目 前人工全膝關節之設計無法重建之。因此， 肌肉控制對人工全膝關節穩定度非常重要。 人工關節之被動運動因前十字韌帶之切除， 在其功能未被代償的情形下，不可能重建正 常關節運動。兩種人工關節對恢復正常運動 各有優缺點，但均不足。當正常膝關節之前 十字韌帶去除之後，其穩定性可藉由後腿肌 30-50%最大收縮力量補償之。其中人工全膝 關節（保留型、替代型）及前十字韌帶缺損 膝關節表現出的型態相似，但是前十字韌帶 缺損膝關節比人工全膝關節較接近正常膝關 節。因此，未來人工全膝關節或許應考慮如 何重建前十字韌帶之功能。 本研究除有助對現有人工全膝關節功能 表現之了解外，更可確保第三年度整合膝關 節電腦模型與己建立之下肢模型以分析功能 性動作之成功執行。Total knee replacement (TKR) has been the main choice of treatment for advanced degenerative knee osteoarthritis over the last few decades. In developing a new prosthesis, it is essential to ensure the functional performance that the prosthesis may bring to the patient. In the present study, the 3D computer graphics-based biomechanical model of the knee joint that was developed in the first year has been used to simulate total knee replacement surgeries for the study of the effects of TKR designs (PCL retaining/substitution) on the biomechanical performance of the knee during functional activities. The results of the study showed that the stability of the knee was significantly reduced after surgery as the stabilizing structures such as ligaments and articular surfaces were removed or changed. Existing total knees were unable to reconstruct the normal stability of the joint. Therefore, muscles are important for knee stability during movement. Since the ACL was removed, normal knee kinematics cannot be recovered simply by TKR without any substituting mechanism for the ACL. Both types of TKR produced passive knee kinematics that was very different from normal. The removal of the ACL reduced significantly the stability of the knee but could be recovered by hamstrings actions with 30-50% level of its maximum force. Responses of the joint with hamstrings action were similar for the two types of TKR and the ACL-deficient knee. It seems that reconstruction of the ACL function may be considered in future TKR designs. The results of the present study will form a strong basis for the execution of the second year project in which the knee model will be incorporated into an existing lower limb model to study the mechanics of normal and prosthetic knees during functional activities

身心障礙者行動輔具之研發與人員之培訓(1/2)─長腿支架功能最佳化設計

長腿支架為廣用於脊髓損傷(SCI)病患之 行動輔具之一。然而傳統支架為保持步行過程 之穩定性，常限制下肢多數關節活動度導致過 大之能量消耗及不自然的步態。有鑑於此，本 計劃乃建立一三維人體模型，以數值計算分析 人體系統之動力特性，並改變人體系統之拘束 條件以模擬穿戴不同輔具時人體之步態及系 統反應的變異性。再利用最佳控制(Optimal Control)理論分析步態週期中之關節力矩，並 應用最佳設計理論(Optimal Design Theoy)進行 長腿支架之實作設計，以期求出使系統耗能最 小之最佳設計。 本計劃如第一年預定時程完成取得受試 者之實驗數據，建立一人體模型，並利用C++ 程式語言撰寫分析程式模擬正常及穿戴輔具 受試者之步態。除以簡化之二維人體模型，進 行一系列不同起始及拘束條件下的數值計算 外，並發展一三維人體模型，以理論先行模擬 評估透過髖膝關節連動式設計之長腿支架於 改善現行長腿支架之可行性。經數值計算證 明，新式設計確實明顯降低行走耗能。因此， 本計劃第二年將依據第一年成果，進行新式支 架之細部設計及臨床評估

A 3D computer graphics-based biomechanical model of the knee joint for the design and evaluation of total knee replacements (3/3)

人工全膝關節置換手術數十年來一直是治療退化性膝關節炎的主要選擇。目標在於有效 消除疼痛、恢復功能性活動度以及提供足夠的關節穩定度。雖然現有設計長期存續率己經相 當高，可是仍有許多改善空間，而未來可能發生的潛在問題在進行新設計時亦需一併考慮。 特別值得注意的是，高存續率並不代表病人膝功能恢復程度的高低。因此，除了持續加強人 工全膝關節本身耐磨耗性與固定外，如何恢復病人術後日常動作的功能，以提高其生活品質， 是現階段新型人工全膝關節設計一個相當重要的課題。 要針對現階段人工全膝關節功能需求，發展一個好的設計，必須先充份了解正常膝關節 的力學與功能。由於道德上的考量以及技術上的限制，直接量取膝關節內力有其困難。是以， 文獻中常以死體試驗研究膝關節。但是，死體試驗不易模擬膝關節之動態荷重。因此，三維 膝關節電腦模型的建立對人工全膝關節設計、測試、手術前規劃以及手術後的復健均極其重 要。基於此，本計畫旨在發展一個三維的膝關節電腦模型以補現階段研究之不足，並分三階 段（年）進行研發。 本計畫第一年完成膝關節三維電腦生物力學模型之建立，並以個別受試者之CT 或MRI 資料將模型個人化。該模型模擬分析正常膝關節於單關節動作（活動度、穩定度與肌力測試） 時之生物力學行為，所得結果與文獻及關節鬆弛度量測和動作分析實驗數據均相當一致。 第二年研究結果顯示，人工全膝關節置換後，膝關節的穩定度明顯下降，因為韌帶及關 節面等被動受力結構被去除或改變，而目前人工全膝關節之設計無法重建之。因此，肌肉控 制對人工全膝關節穩定度非常重要。人工關節之被動運動因前十字韌帶之切除，在其功能未 被代償的情形下，不可能重建正常關節運動。兩種人工關節（保留型、替代型）對恢復正常 運動各有優缺點，但均不足。當正常膝關節之前十字韌帶去除之後，其穩定性可藉由後腿肌 30-50%最大收縮力量補償之。其中兩種人工全膝關節及前十字韌帶缺損膝關節表現出的型態 相似，但是前十字韌帶缺損膝關節比人工全膝關節較接近正常膝關節。因此，未來人工全膝 關節或許應考慮如何補償前十字韌帶之功能。 第三年度計畫的目的在於整合第一年建立之三維膝關節電腦模型與計畫主持人己建立之 下肢模型以分析功能性動作。本階段研究結合步態分析技術以探討進行功能性動作時（步行、 爬梯）正常與人工全膝關節之生物力學行為。本計畫依據既定時程完成膝關節三維電腦模型 與既有下肢模型之整合，並探討功能性動作下膝關節的力學行為，所得結果與文獻韌帶與關 節接觸面力學行為表現一致。本研究有助於充份了解正常膝關節肌肉、韌帶與關節接觸面在 動作中提供膝關節動態平衡時彼此的力學互動。三維膝關節電腦模型與下肢模型的整合對人 工全膝關節設計、測試、手術前規劃以及手術後的復健均極其重要，進而可了解現有人工全 膝關節功能表現。Total knee arthroplasty has been the main choice of treatment for advanced degenerative knee osteoarthritis over the last few decades, aiming at effective relief of pain, recovery of functional mobility and providing sufficient stability. Despite the excellent long-term survivorship of current total knee designs, there are a number of improvements that can be made, as well as potential problems that may emerge in the future. Also, it is noted that good survivorship does not necessarily imply satisfactory functional recovery. Therefore, in developing a new prosthesis, it is essential to ensure the functional performance that the prosthesis may bring to the patient, apart from improving its wear resistance and fixation in the body. Complete knowledge of the function and biomechanics of the natural knee is critical in developing a new total knee prosthesis that is aimed at improving the patient’s function. Due to ethical considerations and technical limitation, direct measurement of internal forces in the knee joint is difficult. In vitro experiments with cadavers thus have been used in the literature to study knee biomechanics. However, it has been agreed that it is difficult to simulate dynamic physiological loading in an in vitro experimental setting. Therefore, a three-dimensional computer graphics-based model of the knee joint will be useful for the design and pre-clinical testing of total knee replacements. It is also important for the evaluation and rehabilitation of patients post-surgery. It is the purpose of the present project to establish such a model. The project was carried out in three stages (years). During the first year, a 3D computer graphics-based biomechanical model of the knee joint was developed. The model was customized to specific subjects with their own CT or MRI data. Simulation study of knee biomechanics during single joint movement (mobility, stability and muscle strength tests) has also been performed and the results validated with experimental data. During the second year, the 3D computer graphics-based biomechanical model of the knee joint that was developed in the first year has been used to simulate total knee replacement surgeries for the study of the effects of TKR designs (PCL retaining/substitution) on the biomechanical performance of the knee during functional activities. The results of the study showed that the stability of knee significantly reduced after surgery as the stabilization structures such as ligaments and articular surfaces were removed or changed. Existing total knees were unable to reconstruct the normal stability of the joint. Therefore, muscles are important for knee stability during movement. Since the ACL was removed, normal knee kinematics cannot be recovered simply by total knees without any substituting mechanism for the ACL. Both types of TKR produced passive knee kinematics that were very different from normal. The removal of the ACL reduced significantly the stability of the knee but could be recovered by hamstrings actions with 30-50% level of its maximum force. Responses of the joint with hamstrings action were similar for the two types of TKR and the ACL-deficient knee. It seems that reconstruction of the ACL function maybe a consideration in future TKR designs. The 3D computer graphics-based biomechanical model of the knee joint developed in the first year has been incorporated into an existing lower limb model developed by the prime investigator. It was used to simulate on the biomechanical performance of the knee during functional activities. The results of the study showed that the mechanical performance of ligaments and articular surfaces were in agreement with the patterns reported in the literature. The results of this 3-year study will be useful for the design and pre-clinical testing of total knee replacements. It is also helpful for the evaluation and rehabilitation of patients post-surgery