This is an interdisciplinary research project in which the methods of biomechanical and design engineering are focused upon a problem in orthopaedics. The anterior cruciate ligament (ACL) is the major ligament in the knee and is often torn during athletic competition as well as every day activity. The ACL is made up of two functional bundles, which help to stabilize the knee. Until recently, ACL reconstruction only replaced one of these bundles; however, research shows that both bundles should be replaced to more fully restore normal knee functionality. The aim of the research was, therefore, to evaluate the mechanical aspects of the double-tunnel-double-bundle ACL reconstruction technique. The research was directed towards designing a new and improved surgical device to improve ACL reconstruction: The current study used a computational model and experimental testing to explore the mechanical parameters of the tendon graft and knee bones to investigate the effects of double tunnel drilling in tibia and femur during ACL reconstruction. The thesis presents the findings of research into three aspects of double-tunnel-double-bundle ACL reconstruction. The first aspect of the study involves clinical and computational analysis of a single-tunnel-singlebundle (SB) ACL reconstructed knee with a double-tunnel-double-bundle (DB) ACL reconstructed example. The study tried to show the advantage of the DB technique over the conventional SB technique. The anatomical geometries of both SB and DB examples were used to create a finite element model and investigate the relative merits of single and double tunnelling, the variations of graft pretension, and tunnel placement on bone stress. The experimental and computational results of both methods were compared and discussed. The second study investigated whether tripling a tendon when using suspensory fixation provides inferior graft strength and a greater cyclical elongation than a doubled tendon graft with suspensory fixation. The tensile stress was found to be lower in the third strand than in the doubled portion. The study was focussed on the mechanical assessment of two different methods of tripling tendons when using suspensory fixation. The third aspect of the study focussed on the design of a new device for fixation of the femoral tripled tendon graft in DB ACL reconstruction technique. The study describes a series of designs and prototypes that were iteratively developed and experimentally tested, leading to a novel tripled tendon graft device. The function of the new device was compared with the conventional methods and tested with a number of animal tendons and bones. The new device with a tripled tendon graft resulted in higher pull-out strength and less graft elongation than that seen using a conventional tripling method.

The tribology of a wide range of designs of compliant layer acetabular cups has been evaluated using a simulator. The simulator applied a dynamic load of 2 kN and a sinusoidal motion of ±25 , and measured the frictional resistance directly. In general the friction developed in these joints was extremely low, with friction factors typically below 0.01. When the experimental results were compared with theoretical estimates of friction a poor correlation was found. Further analysis suggested that the design of compliant layer acetabular cups was insensitive to many of the parameters suggested by theory. In particular, the radial clearance and femoral head size were not found to be critical. In addition, methods were proposed and their effectiveness demonstrated to measure friction at the on-set of motion (start-up friction), and the steady state friction in realistic compliant layer knees. The adhesion between compliant layers and a rigid backing have been investigated, with the aim of developing a good bond between them. The peel test was used to demonstrate an excellent diffusion bond between a low modulus medical grade polyurethane, and a similar high modulus grade of polyurethane. The processing conditions used to manufacture the test piece were optimised to maximise the bond strength. The bond was found to be stable after immersion in Ringers solution at 37 C for 52 weeks, and after acetabular cups were subjected to 14 million 4 kN loading cycles. A six station knee wear simulator was designed and commissioned. The simulator applied a dynamic load and an anterior-posterior translation individually to each station, as well as a flexion-extension motion common to all six stations. The simulator was computer controlled entirely using servo hydraulics. Wear rates were obtained from tests lasting up to 8 million cycles conducted on UHMWPE joints.

No description available.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 126-135. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Donald L. Grimes. / Ph.D.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 117-121. / by Donald T. Darling. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references. / by Ronny N. Galloway. / M.S.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Matthew Valentine Thompson. / B.S.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 66-67. / by Mark L. Tanquary. / M.S.

No description available.