||Lower-Limb Kinematic and Kinetic Analysis for Individuals with Deficient- and Reconstructed-Posterior Cruciate Ligament
||Institute of Biomedical Engineering
本研究的研究對象包含慢性單獨後十字韌帶缺損與接受後十字韌帶重建術後超過一年的患者，根據患者主觀描述再將慢性單獨後十字韌帶缺損患者分為有症狀與無症狀兩組，另外，控制組則是下肢未曾有嚴重肌肉骨骼傷害的健康成年人，每組分別有十名受試者。透過三度空間動作分析系統與力板，分析起立坐下、蹲下與平地行走三項日常動作的下肢關節運動學與動力學。研究目的如下： (1)建立後十字韌帶受傷患者（包括有症狀與無症狀後十字韌帶缺損與後十字韌帶重建術後的患者）從事三項日常活動的下肢生物力學特徵，探討與健康未受傷者之間的差異。(2) 比較患側與健側的各項生物力學參數，探討後十字韌帶受傷患者在動作對稱性的表現。(3) 從受傷後時間、韌帶鬆弛度、與活動程度與動作適應策略各方面，探討可能影響後十字韌帶受傷預後的因素。研究結果歸納如下：(1) 有症狀後十字韌帶缺損患者的下肢運動學與動力學與健康未受傷者較接近，兩側不對稱情形也不顯著；無症狀後十字韌帶缺損患者與健康未受傷者在步態站立末期時膝關節爆發力的表現不同，而且兩側不對稱的現象則普遍地存在於三項動作中。 (2) 無論是受傷後時間、韌帶鬆弛度、或活動程度，有症狀與無症狀後十字韌帶缺損受試者之間都沒有顯著差異，顯示這些因素並不是影響其預後的直接因素，兩組受試者的下肢神經肌肉調適的能力，可能才是影響受傷後預後的主要原因。 (3) 接受單束後十字韌帶重建術後，雖然有可接受的功能回復，但在下肢運動學與動力學方面，從事蹲下與行走時仍存在著與健康未受傷者的差異，而從事站立坐下時也有明顯的兩側不對稱。
Clinical studies of posterior cruciate ligament (PCL) injuries have yielded disparate results. This is especially true for patients with isolated PCL tears as some of these patients recovered reasonably with conservative treatment; others, however, continued to suffer from knee joint pain and instability and were unable to return to their level of activity prior to the injury and thus had to resort to surgical reconstruction. There is a dearth of studies on abnormalities of movement patterns or joint loads in the lower limb of patients suffering from isolated PCL injuries in activities of daily living and whether patients who undergo surgical reconstruction can return to the level of joint kinematics and kinetics they had prior to their injuries. It is necessary to conduct a comprehensive analysis of the kinematics and kinetics of the lower limbs of these patients to gain a better understanding of the clinical performance of patients with isolated PCL injuries, to serve as reference for evaluating the clinical prognosis and establishing treatment strategies.
The participants in this study were patients with chronic isolated PCL injuries and patients who underwent PCL reconstructive surgery more than a year ago. The patients are classified as symptomatic and asymptomatic based on their subjective descriptions of their PCL injuries. The control group, on the other hand, comprises healthy adults that have never suffered from severe musculoskeletal injuries in their lower limbs. Each group comprises 10 participants. This study analyzes the lower limb joint kinematics and kinetics of three tasks – sit-stand-sit, squat, and level walk – using a three-dimensional motion analysis system and two force plates. The aims of this study are as follows. (1) To identify the lower limb biomechanics of patients with PCL injuries (including patients with symptomatic and asymptomatic PCL injuries and patients who underwent PCL reconstructive surgery) when conducting three tasks to identify differences with healthy adults. (2) To compare the biomechanical parameters of the involved and noninvolved sides to determine the motion asymmetry of patients with PCL injuries. (3) To observe factors such as time since injury, ligament laxity, activity level, and movement adaptation strategies following injury to identify possible factors that could influence the prognosis of PCL injuries. The results of this study are as follows. (1) The lower limb kinematics and kinetics of patients with symptomatic PCL injuries had roughly the same performance as the healthy adults did and the asymmetry was not significant. Conversely, the knee joint power at the terminal stance of the gait of patients with asymptomatic PCL injuries was different from those of healthy adults and the asymmetry was evident in all three tasks. (2) There were no significant differences between patients with symptomatic and asymptomatic PCL injuries in terms of time since injury, ligament laxity, and activity level, indicating that these were not key factors that directly influence prognosis. The lower limb neuromuscular adaptive capacity of the two groups might be the key factor that influences prognosis after injury. (3) Single-bundle PCL reconstructive surgery was able to repair some functions, but it was evident that the lower limb kinematics and kinetics of patients were different from that of healthy adults when doing squats and level walks; the patients were also evidently asymmetric when doing sit-stand-sit.
This study pioneers research on the lower limb kinematics and kinetics of patients with isolated PCL injuries. This study divided participants into groups and discovered that patients employed various adaptation strategies, which could be a key factor influencing the prognosis after injury. This study also conducted the same biomechanical analyses on patients who underwent surgical reconstruction to provide a feasible direction for future research.
CHAPTER 1 INTRODUCTION 1
1.1 Research Background 1
1.2 Overview of the Posterior Cruciate Ligament Injury 2
1.2.1 Anatomy and Function of the Posterior Cruciate Ligament 2
1.2.2 Mechanism of Injury 3
1.2.3 Incidence of Injury 3
1.2.4 Classification and Treatment Strategy 4
1.2.5 Natural History of Nonoperatively Treated Isolated PCL Injuries 6
1.2.6 PCL Reconstruction: Techniques and Clinical Outcomes 9
1.3 Purposes of This Study 11
1.4 Hypotheses 13
CHAPTER 2 LITERATURE REVIEW 14
2.1 Biomechanical Properties of the PCL 14
2.1.1 PCL Forces during Different Conditions 14
2.1.2 Three-Dimensional Deformations of the PCL 17
2.2 Biomechanics of PCL Deficiency 17
2.2.1 Effect of Cutting PCL on the Knee Laxity- In Vitro Studies 17
2.2.2 In Vivo Kinematics and Kinetics of PCL Deficiency 20
2.3 Biomechanics of PCL Reconstruction 24
2.3.1 Effect of PCL Reconstruction on Restoration of the Knee Stability and Kinematics- In Vitro Studies 24
2.3.2 In Vivo Kinematics and Kinetics of PCL Reconstruction 26
CHAPTER 3 RESEARCH DESIGN AND METHODS 28
3.1 Subjects 28
3.1.1 Subjects with Chronic Isolated PCL Deficiency 28
3.1.2 Subjects with PCL Reconstruction 29
3.1.3 Normal Controls 29
3.2 Instrumentation 32
3.3 Procedure 32
3.4 Data Processing 34
3.4.1 Spatiotemporal Variables 37
3.4.2 Kinematic Variables 38
3.4.3 Kinetic Variables 38
3.5 Statistical Analysis 39
CHAPTER 4 RESULTS 40
4.1 Performance Consistency 40
4.2 Between-Group Comparisons 41
4.2.1 Walk Tasks 41
4.2.2 Sit-Stand-Sit Tasks 48
4.2.3 Squat Tasks 54
4.3 Symmetry: Between-Limb Comparisons 60
4.3.1 Symptomatic PCLD group 60
4.3.2 Asymptomatic PCLD group 64
4.3.3 PCLR group 73
CHAPTER 5 DISCUSSION 81
5.1 Selection and Categorization of Subjects 81
5.2 The Biomechanical Characteristics and Influencing Factors of the Three Tasks 82
5.2.1 Walk Tasks 82
5.2.2 Sit-Stand-Sit Tasks 83
5.2.3 Squat Tasks 85
5.3 Movement Adaptation Strategies Adopted after PCL Injuries 87
5.3.1 PCLD Groups 88
5.3.2 PCLR Group 92
5.4 Limitations of This Study 94
5.5 Future Directions 95
CHAPTER 6 CONCLUSIONS 96
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