Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 254-261).

Introduction: Gait biomechanics are associated with knee osteoarthritis (OA) structural progression, but no studies have included: i) all three lower extremity joints, ii) non-frontal plane factors, iii) temporal loading patterns, and iv) progression from structural and symptomatic perspectives. This dissertation addressed gaps in our understanding of lower limb biomechanics and their implication for determining whether we have identified and are targeting the most effective biomechanical variables in the development and evaluation of conservative interventions to slow knee OA structural and symptom progression (progression to TKA). Methods: 54 patients with knee OA underwent baseline gait analysis. Three-dimensional hip, knee, and ankle angles and moments were calculated. Waveform characteristics were determined using Principal Component Analysis (PCA), and knee adduction moment (KAM) peak and impulse were calculated. At follow-up 5-8 years later, 26 patients reported undergoing total knee arthroplasty (TKA). Unpaired Student’s t-tests detected differences in baseline demographic and gait characteristics between TKA and no-TKA groups. Receiver operating curve analysis determined discriminative abilities of these differences. Stepwise discrimination analysis determined which multivariate combination best classified the TKA group. Logistic regression analysis determined the predictive ability of the multivariate model. Results: There were no baseline differences in clinical and spatiotemporal gait characteristics, but the TKA group showed significant gait biomechanical differences, including higher KAM magnitude (KAMPC1), less difference between early and mid-stance KAM (KAMPC2), higher KAM peak and impulse, reduced early stance knee flexion and late stance knee extension moments (KFMPC2), and reduced stance dorsiflexion moments (AFMPC4). The multivariate discriminant function with the highest classification rate (74.1%) combined KAMPC1, KFMPC2, and AFMPC4, with sensitivity of 84.6 and specificity of 71.4. A one-unit increase in the model score increased risk of progression to TKA six-fold. Conclusion: Higher KAMPC1 scores suggest higher overall loading during gait. Lower KFMPC2 and AFMPC4 scores suggest inability to unload the knee and therefore sustained loading. Interventions reducing overall load and altering patterns of loading (i.e. increase unloading) may reduce risk of progression to TKA. Future research should determine how components of the discriminant model can be altered conservatively, and what impact alterations have on the risk of progression to TKA.

Background: Total knee arthroplasty (TKA) is a well-established surgical operation. Some epidemiology studies showed that TKA operations continue to improve in developed and developing countries. However, among these operations, the satisfaction rating of TKA outcomes was much lower than those of total hip arthroplasty (THA) (75% vs. 97%). / The knee joint is kinematically more complex than the hip joint because of its wider range of movement, including sliding and rotation during flexion, which make it difficult to restore function. Many investigations demonstrated that malalignment and unbalanced soft tissue tension are two major factors that influence the functional restoration of knee joints after TKA. Restoration of the lower limb mechanical axis is now easier to achieve owing to the development of the computer navigation system. However, balancing soft tissue tension still remains a problem, making it a subject of great interest in research. / A group of researchers pointed out that the conventional TKA method focuses too much on the restoration of the mechanical axis but neglects its anatomic and kinematic considerations. This notion led to their proposal of another method, namely, kinematical alignment, which is not perpendicular to the mechanical axis but parallel to the posterior condylar axis. Some clinical studies showed that the short-term and mid-term outcomes of kinematically aligned TKA knees achieved pain relief and functional restoration better. However, the underlying mechanisms have not been studied. / The current study aims to investigate the underlying mechanisms of the kinematical alignment method in four aspects: anatomy, kinematics, biomechanics, and bone preservation. We hypothesize the following. 1. The posterior condylar axis is more reliable than the epicondylar axis as a reference for TKA operations and anthropometrical studies of the knee joint. 2. The kinematical alignment method preserves the bone cutting volume better than the mechanical alignment method. 3. Varus deformation influences the kinematics and biomechanics in the tibiofemoral joint of the normal knee during static standing and flexion. 4. Kinematical alignment is better than the mechanical alignment in restoring normal kinematics and biomechanics for TKA knees during flexion. 5. Kinematical alignment may increase stress at the medial side of the tibiofemoral joint of TKA knees at static standing posture. / Methods: 1. In this study, a clearer and easily reproducible marking area on the posterior femur condyle surface was defined, from which an axis was obtained, namely, the newly defined posterior condylar axis (NPCA). Based on the NPCA, a coordinate system of the knee joint was established. Anthropometrical study of the NPCA and the clinical epicondylar axis (CEPA) were carried out on 52 normal Chinese subjects (50–80 years old, female: male = 1:1). 2. A weight-bearing magnetic resonance imaging (MRI) experiment was further designed and carried out on the normal subjects and the knee osteoarthritis (OA) patients. Eight MRI scans were performed at flexion angles of 0°, 20°, 40°, and 60° with and without placing an 18 kg weight on each volunteer. After scanning, the three-dimensional geometries of the knee bones were reconstructed, and abduction angles of the normal and varus knees were measured and compared. 3. Simulations of bone osteotomy according to mechanical alignment and kinematical alignment methods were performed on 12 varus OA knees. Bone volumes of the distal femur cut, proximal tibial cut, anterior and posterior femur cut, and anterior and posterior chamfer cut of the two alignment methods were measured and compared. 4. From the MRI image of a young healthy volunteer, a finite element model of the normal knee with a varus angle of 0° was constructed. Based on this initial construction, another 5° deformed varus knee model was also constructed. Varus deformation simulation was perform on the normal knee. Static standing simulation and flexion simulation were applied on both normal and varus knee models. 5. Two finite element models of the mechanically and kinematically aligned TKA knees were constructed based on the normal knee model. Static standing simulation and flexion were also applied on the two TKA knee models. / Results: The anthropometrical study showed that the angle between the NPCA and CEPA was about 3.5° on the coronal plane and 1.2° on the axial plane regardless of alignments. Moreover, the CEPA was nearly perpendicular to the lower limb mechanical axis in all alignment groups, whereas the NPCA was more orthogonal to the femoral mechanical axis in the varus group. The NPCA was also almost parallel to both inferior and posterior condylar lines in all alignment groups, whereas the CEPA was only parallel to the posterior condylar line. / The weight-bearing MRI experiment showed that as the knee flexed from 0° to 60°, the abduction angles of normal knees increased from -1° to 2°, whereas those of varus knees decreased from 4° to 3°. Significant differences in abduction angles were found between normal and varus knees at flexion angles of 0°, 20° and 40° with or without weights. No significant difference was found between weight-bearing and non-weight-bearing conditions in both normal and varus knees. / The bone osteotomy simulation showed that the kinematical alignment method saved 49.1±6.0% of bone volume in the distal femur cut, 26.3±10.4% in the posterior femur cut, 35.6±5.4% in the tibial plateau cut, and 28.4±4.4% in total. / The varus deformation simulation showed that as the knee varus angle increased from 0° to 5°, the peak stress linearly increased at a rate of 0.8 MPa per varus angle in the medial tibial cartilage, but decreased at a rate of 0.2 MPa per varus angle in the lateral tibial cartilage. Moreover, stress was almost equally distributed in the medial and lateral tibial cartilages of the normal knee at static standing posture, whereas stress localized in the medial tibial cartilage of the varus knee. / Flexion simulation of the normal and varus knees showed that peak stress in the medial tibial cartilage of the varus knee decreased sharply from 2.18 MPa to 0.87 MPa as the knee flexed from 0° to 20°. Peak stress in the medial and lateral tibial cartilages of the normal knee was also almost equal at all flexion angles, whereas similar peak stress was observed in the varus knee only after a flexion angle of 20°. / Static standing simulation of both TKA knees showed that lateral tibial peak stress in the mechanically aligned TKA knee was approximately 0.2–0.8 MPa higher than that in the kinematically aligned TKA knee. Meanwhile, the medial tibial peak stress in the kinematically aligned TKA knee was approximately 0.5–1.2 MPa higher than that in the mechanically aligned TKA knee. / Flexion simulation of post-operative knees showed that stress was nearly equally distributed in the medial and lateral tibial inserts of the kinematically aligned TKA knee as the knee flexed from 0° to 50°. Moreover, axial rotation angles in the kinematically aligned TKA knee were approximately equal to those in the normal knee during flexion, whereas in the mechanically aligned TKA knee, the femur condyle was axially rotated in the opposite direction. Load partially transferred through the medium spine after a flexion angle of 40°, and peak stress in the medium spine was at least four times higher than those in the concaves of the insert component. / Conclusion: NPCA is more reliable than CEPA as a reference to determine the axial and rotational alignments of the femoral condyle for TKA surgeries and anthropometrical studies of the knee. Kinematical alignment is also better than the mechanical alignment in preserving the bone cutting volume by nearly 30%. / Varus deformation significantly shifts the stress to the medial side of the knee in a static standing posture, but its effect is reduced during flexion. It indicates that the inferior side of medial femoral condyle would be more likely to suffer knee OA rather its posterior side from the biomechanical view. / Kinematical alignment increases stress at the medial tibiofemoral joint of the TKA knee in a static standing posture, which may influence its long-term condition. However, kinematical alignment is better than mechanical alignment in restoring normal kinematics and biomechanics for TKA knees during flexion. Peak tibiofemoral contact force in the normal and TKA knees can reach four to six times the body weight in a squatting position. Thus, restoring normal kinematics and biomechanics during flexion is important. / 背景：全膝关节置换术（TKA）已成为一种常规手术。一些流行病学研究显示TKA在发达国家和发展中国家都呈持续增长趋势；然而与全髋关节置换术（THA）相比，TKA的满意度要明显低于THA（75% vs 97%）。 / 从运动学角度观察，膝关节运动学结构要比髋关节复杂：在膝关节弯曲过程中，其内既有滑动又有轴向转动，以至于很难恢复其功能。许多研究人员证明下肢力线错位和膝关节内部软组织不平衡是影响TKA术后其功能恢复的两个主要原因。得益于计算机辅助导航系统的发展，正常下肢力线已经能够较容易实现恢复；但是如何做好膝关节软组织平衡还是一个悬而未决的问题，目前许多相关研究正在进行当中。 / 最近有一组研究人员指出传统的TKA手术方法太过于关注恢复下肢力线，而忽略了其解剖和运动学方面的因素，而这对实现软组织平衡至关重要。基于上述原因，他们提出了一种新的截骨方法——运动学对线。基于这种截骨方法，其股骨远端截骨面不再垂直于下肢力线，而是平行于股骨后髁轴线。一些临床研究结果已经表明运动学对线的TKA术后的短期疼痛舒缓和中期功能恢复效果都要优于力学对线的TKA；然而其内在机理尚未被研究。 / 本次课题拟从四个方面去研究运动学对线的截骨方法的内在机理：解剖学、运动学、生物力学和节约骨量。我们假设： 1. 股骨后髁轴线比股骨髁间轴线更加稳定，更适合作为膝关节置换术和膝关节形态测量的参考轴线； 2. 相比力学对线的方法，运动学对线的方法能够有效减少截骨量； 3. 膝关节畸形内翻会改变其胫股关节在站立位和弯曲过程中的运动学和生物力学特性； 4. 运动学对线的方法可能会增加TKA术后的胫股关节在站立位时的内侧应力； 5. 运动学对线的方法比力学对线的方法更能有效的恢复TKA术后膝关节在弯曲过程中的正常运动学和生物力学特性。 / 方法： 1. 本次研究提出一种更加清晰的、易重复的股骨后髁接触表面的边界定义方法；基于这个表面拟合出一个圆柱，其轴线即为——新股骨后髁轴线（NPCA）。基于NPCA建立了膝关节的坐标系统，且设计了一套人体形态学测量方法测量了52位中国人的股骨NPCA和髁间轴线（CEPA）（年龄：50~80；男：女=1:1）。 2. 设计了一组负重核磁共振（MRI）试验去测量健康和膝关节炎（OA）患者的胫股关节运动学特性。基于特殊设计的试验工具，每一位志愿者都进行了0°、20°、40°和60°膝关节弯曲角度下的，以及负重与非负重状态下的共8组MRI扫描。扫描完成后，膝关节骨性结构的三维几何模型被重建出来，其正常与内翻膝关节的外展角度也被测量出来并进行比较。 3. 对12只内翻膝关节分别进行了力学对线和运动学对线的两种不同截骨方法的截骨模拟。两种截骨方法下的股骨远端截骨、胫骨近端截骨、股骨前髁与后髁截骨、以及股骨前髁与后髁倒角截骨的骨量都被分别计算出且进行比较。 4. 基于一位年轻健康志愿者的MRI图像建立了0°内翻的正常膝关节的有限元模型，且在其基础上另建立5°内翻的膝关节模型。之后，对正常膝关节模型进行了内翻模拟分析；且对正常和内翻膝关节模型都分别进行了站立位和弯曲运动的模拟分析。 5. 基于正常膝关节模型建立了力学对线和运动学对线的两种TKA膝关节模型。之后，对两种TKA膝关节模型都分别进行了站立位和弯曲运动的模拟分析。 / 结果：人体形态学测量结果显示正常、内翻和外翻膝关节的NPCA与CEPA之间的夹角在冠状面都约为3.5°，在横断面都约为1.2°。此外，三组膝关节的CEPA都几乎与下肢力线垂直；而内翻组的NPCA比其CEPA更加垂直于其股骨力线。再者，所有膝关节组的NPCA都几乎同时平行于股骨下髁和后髁切线，而其CEPA却只平行于股骨后髁切线。 / 负重MRI实验结果显示在膝关节0°至60°弯曲过程中，正常膝关节的外展角从-1°增至2°；而内翻膝关节外展角从4°减至3°。正常与内翻膝关节在0°、20°和40°弯曲角度时的外展角表现出显著差异；然而正常与内翻膝关节在负重与非负重情况下的外展角都无显著差异。 / 截骨模拟结果显示运动学对线的截骨方法节约了49.1±6.0%的股骨远端截骨骨量、26.3±10.4%股骨后髁截骨骨量、35.6±5.4%胫骨近端截骨骨量，总计节约28.4±4.4%的截骨骨量。 / 内翻模拟分析结果显示在正常膝关节从0°內翻至5°过程中，其内侧胫骨软骨中的最大应力以0.8MPa每内翻角的速率线性递增；而其外侧胫骨软骨中的最大应力却以0.2MPa每内翻角的速率线性递减。此外，站立位时正常膝关节的内外侧胫骨软骨中的应力呈均匀分布；而内翻膝关节中的应力则高度集中在内侧胫骨软骨中。 / 正常和内翻膝关节的弯曲模拟分析结果显示内翻关节在从0°弯曲至20°过程中，其内侧胫骨软骨中的最大应力从2.18MPa急剧减少至0.87MPa。此外，在所有弯曲角度下，正常膝关节内、外侧胫骨软骨中的最大应力值相近；而在内翻关节中类似情况仅在20°弯曲角度后出现。 / 两种TKA膝关节模型的站立位模拟分析结果显示：力学对线的TKA膝关节的外侧胫骨衬垫最大应力比运动学对线的TKA膝关节的外侧胫骨衬垫的最大应力要高0.2至0.8MPa；而运动学对线的TKA膝关节的内侧胫骨衬垫最大应力比力学对线的TKA膝关节的内侧胫骨衬垫的最大应力要高0.5至1.2MPa。 / 两种TKA膝关节模型的弯曲模拟分析结果显示：在膝关节从0°弯曲至50°过程中，运动学对线的TKA膝关节胫骨衬垫内外侧的应力近于平均分布。此外，运动学对线的TKA膝关节在所有弯曲角度下的轴向旋转角度都与正常膝关节的近乎一致；而力学对线的TKA膝关节的轴向旋转角度却与其方向正好相反。在40°弯曲角度以后，部分应力将通过衬垫中部突柱传递；且中部突柱内的最大应力要高出衬垫凹窝内的最大应力至少四倍。 / 结论：NPCA是比CEPA更为稳定的能判定股骨髁轴向和弯曲旋转对齐状态的参考轴线，可更好的辅助TKA手术和膝关节形态学测量研究。此外，与力学对线的截骨方法相比，运动学对线的截骨方法能节约将近30%的截骨骨量。 / 内翻畸形形变会显著增大膝关节在站立位时的内侧应力，但这一影响会在弯曲过程中削弱。这一结果表明从力学角度观察股骨下髁比股骨后髁更容易患骨性关节炎及更容易产生形变。 / 运动学对线的方法增加了其TKA膝关节在站立位时内侧应力，这可能会影响其关节假体的远期使用寿命；然而在弯曲运动过程中，运动学对线的方法比力学对线的方法能更好的恢复其TKA膝关节的正常运动学和生物力学特性。由于在下蹲过程中，正常与TKA膝关节中胫骨关节内最大接触压力可达人体体重的4至6倍；因而恢复弯曲过程中的正常运动学与生物力学特性显得更为重要。 / Shi, Dufang. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 281-289). / Abstracts also in Chinese. / Title from PDF title page (viewed on 14, September, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Lynn Snyder-Mackler, Dept. of Physical Therapy. Includes bibliographical references.

Abstract Since Mar. 1995, the National Health Insurance begin in Taiwan, the payment of health insurance gradually increase each year. For controlling the increasing costs, case payment was the most important method. For each hospital, using clinical pathway to control costs of case payment was an effective tool. But, there were still less literatures to discuss the efficiency of clinical pathway in Taiwan. We used a retrospective study design, to examine the length of stay, total costs and quality including the complications, morbidity and readmissions for total knee replacement surgery. The data before clinical pathway was from June 2001 to May 2002, total 219 cases. After clinical pathway, the data was from Jan. 2003 to Dec. 2003, total 207 cases. The results showed decrease length of stay from 7.4 to 6.6 days (10.8%), decrease total cost from 125,324 NTS to 119,100 NTS (4.97%) and the quality of complications and readmissions did not increase. In conclusion, the clinical pathway can improve length of stay, total costs and quality. Key words: case payment, clinical pathway, total knee replacement

Thesis (M.S.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references.

The objective of this thesis was to develop a concept and methodologies for designing a total knee replacement (TKR) with normal kinematics and a high range of motion. The design philosophy was that a TKR can function similar to the normal knee, provided that after TKR the inherent passive characteristics of the joint are restored to normal with minimum disruption in the functions of the remaining structures of the joint. As the first step prior to design, cadaver experiments were conducted and biomechanical models of the passive knee were developed to study the mechanics of the normal knee. The guiding roles of the tibial articular surface including the menisci, the combined effects of the cruciates and contact forces, and the elongation patterns of the cruciates were investigated. Based on the results obtained from these studies and the relevant information in the literature, design requirements for a TKR with normal kinematics were identified, and an innovative design concept was introduced. On the medial compartment of this design the shape of the articular surfaces resembled a ball-and-socket joint, and on the lateral side a pair of guiding bearing surfaces mimicked the guiding roles of the cruciate ligaments. The novelty in the design concept lies in the design of the shape of the lateral articular surfaces. The progressive variations of the curvature of the medial and lateral aspects of the lateral condyle generate the desired guiding effect for the full cycle of extension and flexion. The bearing spacing defined as the distance between the medial and lateral contact points was kept constant throughout the motion, as this was proved to be necessary to ensure compatibility between the geometry of the bearing surfaces and the desired pattern of motion. Appropriate methodologies were developed to generate the complete shapes of the bearing surfaces and to build the prototypes based on the constraints of the bone geometries and kinematics of a sample cadaver knee. The kinematic test of the prototype proved the viability of the design concept and methodologies. The novel design philosophy, concept and methodologies developed in this thesis provide a foundation for a new generation of TKR with normal kinematics. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-09-18 16:56:02.502

Thesis (M. Med. Sc.)--University of Hong Kong, 2004. / Also available in print.

Thesis (M. Med. Sc.)--University of Hong Kong, 2005. / Also available in print.

With the increasing advocacy for maintaining a healthy lifestyle in regards to exercise and the average age of the population in the U.S. growing older, there has been an increased incidence of arthritic knee damage as a result of osteoarthritis. Once non-procedural methods of treatment have been exhausted, such as NSAIDs and physical therapy, the most effective therapy to regain previous range of motion and quality of life is total knee arthroplasty (TKA). Additionally, TKA is useful to treat patients with rheumatoid disease once their knees have reached end-stage cartilage damage, although it does not restore function as well in these patients as it does in patients with osteoarthritis. Current technological developments have produced prostheses that mimic physiological movement and allow attachment of components positioned similarly to ligaments in the human knee, providing better longevity and functional recovery from the damaged state. The TKA procedure has become fast-tracked to limit the length of stay for patients and the cost to both the individual and the hospital. Though this change to fast-track procedures has helped limit post-operative complications, such as venous thromboembolism, multiple comorbidities and componentry failure continue to increase the risk of failure or revision of the procedure. With the projected increase in the need for TKAs in the future, it is important to review factors that may influence access and success of this procedure, for example, the effect socioeconomic status has on the ability of different patients to receive quality replacements and experience sustained quality of life. Multiple studies have shown that utilization of TKA differs between low income and high income populations, with racial minority populations undergoing the procedure less often as they represent a greater percentage of low income populations. Interestingly, low income patients report greater improvement in function when compared to high income patients, most likely due to low income patients being admitted with more severe knee damage when compared to the other population. Their satisfaction, along with financial constraints and insurance, are factors that lower the rate of revision for low income populations even though their measured range of motion post-operatively is not as good as that in high income populations on average. Social support has been determined to be a significant factor in determining whether patients will undergo TKA and follow the rehabilitation prescribed to them appropriately. Studies have shown less social support reported from minority groups, but not low income cohorts specifically. Using the current knowledge of the impact these differences in socioeconomic status can have on the outcomes of TKA, can help create healthcare environments which will optimize the success rate of TKA for all patients, regardless of socioeconomic status, and prevent unnecessary strain on the healthcare system due to avoidable post-operative issues. Future studies should determine what policies and procedures can be implemented to help aid patients, such as greater social support, and to support hospitals with limited resources in an effort to improve surgical outcomes.