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

In the project a method to calculate the displacement of hip prostheses inside a hip socket is made. The project, performed as a bachelor thesis project is a cooperation between Karolinska Institute and Uppsala University. Hip replacements are expensive surgeries. Loosening is a large problem for orthopedists and patients, and costs both time and expenses. If dislocations of hip prostheses are detected in an early stage, preventions to reduce the loosening can be done. The method is programmed in Matlab code utilizing Computational Tomographic Images (CT). The CT images are built up by putting 0.5 [mm] wide X-ray slices after each other. In the project a model of a human hip made of plastic is used with two real hip prostheses, one for each hip, and small balls, around some [mm] in diameter, made of tantalum are located inside the plastic bone. The purpose of the tantalum balls are to mark the bones’ position and makes it easier toget exact coordinates from the X-ray images of the bone structure.

The focus of the research described in this section of the thesis is the synthesis of compounds expected to bind strongly to both the estrogen β and α receptors and act as estrogen agonists. Based on earlier results in our group and docking studies we prepared a series of A-CD analogs, compounds 1, in which the usual 13-methyl group was replaced by an ethyl group. Docking studies also indicated that substituents at C8 could lead to enhancement of binding to the estrogen receptor. With this in mind two such derivatives, compounds 2 were prepared. A major concern in the use of estradiol in hormone replacement therapy is its potential metabolism of dangerous ortho-quinones. The 1,2-naphthalenediol derivatives 3 avoid this possibility. They were predicted to be potent binders to the estrogen receptors with the naphthalene diol portion serving as rings A and B and the hydroxyl group taking the place of the 17-OH group of estradiol. The preparation of several derivatives of 2 is reported. The estrogen receptor binding [ERB] relative to estradiol as standard has been determined at the University of Illinois for a number of the compounds prepared in this thesis. Unfortunately, the results were not as encouraging as expected. Importantly, all of the 13-ethyl derivatives tested showed lower binding affinity compared to the 13-methyl analogs. Similarly, the derivatives with substituents at C8 do not show higher activity than those having only hydrogens at C8. Finally, the situation with the naphthalene derivatives is, at this stage, still not completely resolved. The binding for the compounds thus tested is quite low, but it must be admitted that the structures thus far synthesized have a much lower LogP than estradiol, a factor known to greatly decrease the binding constants to the estrogen receptors.

As implant survival extends into the second and third decades focal osteolysis around cemented femoral components in total hip replacement is emerging as an important failure mechanism. Whilst the problem of focal osteolysis is well recognised, there are many aspects of its development which are poorly understood. The broad aim of this thesis is to try to provide some insights into how, why and where focal osteolysis develops around the cemented femoral component. There are broadly two sections to this thesis, chapters 2-5 present clinical and geometrical studies and chapters 6-10 a series of experimental studies. The aim of the first section was to establish what is observed in clinical practice, the aim of the second to try to explain these findings. A mid-term clinical study showed that focal osteolysis is more common with rough than polished stems that differed in no aspect other than their surface finish. Further studies established that focal osteolysis is probably always associated with defects in the cement mantle. These defects occur anteriorly at the mid-stem of the prosthesis and posteriorly at the component tip. The distribution of focal osteolysis and its strong association with cement mantle defects suggests the importance of the stemcement interface as a pathway for fluid and debris to reach the distal femur. However, at 15-25 years, osteolysis rarely develops with the polished Exeter stem even in the presence of confirmed defects in the cement mantle, suggesting that the stem seals the stem-cement interface against fluid and debris. In an attempt to explain the clinical findings a series of bench top experiments were undertaken. These studies showed that the behaviour of fluid and dye at the stemcement interface was significantly influenced by component surface finish. Bonded and debonded stem-cement interfaces of rough stems provided an incomplete barrier to fluid movement along this interface. In contrast, polished stems both bonded and debonded were able to provide a seal at the stem-cement interface. The seal at this interface was improved with component subsidence in the presence of rotational stability. It is believed that this thesis provides a rationale explanation for why focal osteolysis rarely develops around the Exeter stem in clinical practice. It also explains how, where, and why osteolysis develops around certain designs of cemented femoral components used in total hip replacement.

Thesis (MAppSc in Physiotherapy) -- University of South Australia, 1998

Thesis (MAppSc in Physiotherapy) -- University of South Australia, 1998

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 94-95). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves 75-85).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 102-113).

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 58-59). Also available on the World Wide Web.