Theses and DissertationsFall 2017 A computational investigation of patient factors contributing to A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint contact stress abnormalities in the dysplastic hip joint ABSTRACT Acetabular dysplasia, a deformity characterized by the presence of a shallow acetabulum inadequately covering the femoral head, alters force transfer through a joint, causing early-onset hip pain and degeneration. Dysplasia is often treated surgically with a periacetabular osteotomy (PAO), which permits multiplanar acetabular reorientation to stabilize the joint and alleviate pain. PAO alters joint mechanics, including contact stress, which can be assessed via computational methods.This work sought to enhance a discrete element analysis (DEA) model for assessment of the dysplastic hip. The primary focus was on understanding how the gait parameters used to load a DEA model affect the computed contact stress. Several additional studies focused on understanding specific anatomic and demographic factors contributing to the contact stress evaluation were also performed.Implementation of a dysplastic gait pattern to load the DEA models resulted in more cases with improved contact stress and clinical measures after PAO, which concurred with clinical findings. Patient demographics and acetabular and femoral geometry all affected the computed contact stress distributions, emphasizing the importance of proper cohort categorization prior to interpretation of DEA-calculated contact stress. These results indicate that accurate modeling of the particular deformity in this cohort likely requires evaluation of both functional and anatomic differences.These studies improve the ability to realistically model and characterize dysplastic hip contact mechanics. DEA is a valuable tool for assessing contact stress in dysplastic joints, which has the potential to improve patient outcomes by guiding clinicians in nonoperative treatment, pre-operative PAO planning, and evaluating intraoperative success. iv PUBLIC ABSTRACTHip dysplasia is a deformity of the pelvic bone that results in a mechanically unstable hip joint. This can be painful and lead to development of arthritis at a young age.Treatment may involve surgery to change how the hip socket is positioned and oriented in the pelvis to improve hip stability and decrease the damaging, painful stresses on the hip socket. Success of this realignment is largely determined by the ability of the surgeon to determine hip function in 3D from 2D X-ray images that can be obtained during surgery.Computational modeling offers the opportunity for analysis of joint mechanical function in 3D, which provides a much more realistic assessment of the mechanical changes after surgery.The purpose of this work was to develop the best method for using a specific type of computational modeling to evaluate changes in the joint mechanics of dysplastic hips before and after corrective surgery. This involved an investigation of mo...

in external knee adduction moment (EKAM), pain reductions when comparing to a neutral insole has unfortunately not shown a significant effect. A treatment that has shown good clinical results are simple knee sleeves, but these do not alter the mechanical loading at the knee and thus combining both of these is an attractive option. This study aimed to investigate the effect of using a lateral wedge insole and simple knee sleeve as a combined treatment, and compared this approach to using each treatment individually over a 6-week period. Methods: To date: eighteen male participants have been recruited; all were diagnosed with medial knee OA radiologically and clinically via American College of Rheumatology (ACR) criteria. Participants completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) evaluation one week before starting the trial and in the first visit before using the group-assigned treatment. The participants were randomised to one of three treatment groups: the insole group, the sleeve group and the combined group (insole þ sleeve group). Each group consisted of six participants. Gait analysis was conducted during the first visit before applying the treatment. KOSS and gait analysis were reassessed after 6 weeks of treatment. Results: The age, height and mass demographic characteristics were very similar among the participants (age: 59, 55.3 and 55.6; height: 1.68 m, 1.72 m and 1.69 m; weight: 83.3 kg, 91.1 kg and 93.7 kg), in the combined group, sleeve group and insole group, respectively. When comparing to the groups at baseline outcomes were similar although the sleeve group did have a higher KOOS pain score. After six weeks of treatment, the combined group and the insole group showed reductions in EKAM compared to their baseline readings. Whilst the sleeve group showed a small increase in EKAM after the six weeks. However, the KOOS pain score showed a good reduction in all groups compared to their baselines. First peak knee adduction moment (EKAM) Nm/Kg