No description available.

Thesis (M.S.M.E.)--University of Delaware, 2009. / Principal faculty advisor: Jill S. Higginson, Dept. of Mechanical Engineering. Includes bibliographical references.

Knee osteoarthritis (OA) causes more disability in community dwelling older adults than any other condition. The high costs associated with treating this disability suggest that research needs to focus on ways of preventing the development and progression of knee OA using low cost interventions such as exercise and modifications to certain activities of daily living. One such activity of daily living that has been implicated in the OA disease process is normal level walking or gait. Those with medial compartment knee OA are known to make certain modifications in their gait patterns in an attempt to unload the diseased compartment of their knee. Two of these modifications include the tendency of those with knee OA to walk with an externally rotated foot, and to increase the activity of their lateral hamstrings, while decreasing the activity of their medial hamstring during gait. Therefore, this work attempted to clarify this relationship between foot position, lower extremity loading and hamstring muscle activation patterns during both level walking and lower limb exercise. First, the changes in lower extremity loading with both internal and external rotation of the foot during gait were investigated in a group of young healthy subjects. It was discovered that internal rotation increased the magnitude of both the adduction moment and the medial-lateral shear force at the knee; while external rotation decreased both these measures. This suggests that external foot rotation may be an effective compensation strategy for those with medial knee OA and internal foot rotation may be an effective compensation strategy for those with lateral knee OA. Second, the same study was then repeated in a group of knee OA subjects and age matched healthy normal subjects; but in this work, hamstring EMG was also collected along with the external knee loads. Hamstring EMG data was used to calculate the medial-lateral (M-L) hamstring activation ratio. An increased M-L activation ratio would indicate an internal muscle moment tending to load the medial compartment more than the lateral; while a low M-L activation ratio would tend to unload the medial compartment. Those with knee OA had an increased late stance knee adduction moment and a decreased M-L hamstring activation ratio as compared to the healthy control group. Also, external foot rotation decreased the late stance knee adduction moment, lateral-medial shear force at the knee, and M-L hamstring activation ratio for both groups; but, internal foot rotation did not increase these measures. Lastly, since it is apparent that the hamstring may play a role in unloading the diseased knee compartment, the M-L activation ratio was calculated with changes in foot position during lower limb exercise in young healthy subjects to determine if selective activation of the medial or lateral hamstrings was indeed possible. It was discovered that internal foot rotation increases the M-L hamstring activation ratio and external rotation decreases it. Foot rotation has the ability to shift the external loads on the knee to one side of the joint or the other, and it also has the ability to alter internal knee loads created by hamstring muscular activation. Therefore, foot rotation during gait and lower limb exercise may be an effective intervention that could be used to delay the onset and progression of knee OA, keeping older adults active and healthy much longer. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2007-09-28 14:31:23.908

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Todd D. Royer, Dept. of Health, Nutrition, and Exercise Sciences. Includes bibliographical references.

Knee osteoarthritis (OA) is a debilitating and costly chronic health condition affecting approximately 10% of Canadians. Total Knee Arthroplasty (TKA) is an effective procedure restoring quality of life and providing pain relief for patients with knee OA. The benefits of TKA are well established for patients with knee OA, but determining those who would most benefit is a challenging task. Physical functioning in patients with knee OA has been shown to be a key factor for appropriateness for TKA. The Lower Extremity Functional Scale (LEFS) and the Oxford Knee Score (OKS) are two patient-reported outcome measures (PROMs) measuring physical function that can be utilized to assist health care professionals in determining the need for TKA among this population. The LEFS is a regional PROM consisting of 20 questions asking about activities relating to lower extremity functioning. Questions are scored on a 5-point descriptive scale from 0 (extreme difficulty or unable to perform the activity) to 4 (no difficulty) with a total score of 80. Higher scores represent higher functioning. The OKS is a site-specific PROM that asks questions about pain and function and consists of 12 items ranked on a 5-point descriptive scale. Scores range from 1 to 5 (total score of 60) for each item with lower scores representing higher function. The purpose of this thesis was to determine the diagnostic accuracy for the LEFS and the OKS for determining appropriateness for TKA in people with primary knee OA. The hypothesis for the current study was that the LEFS would have higher diagnostic accuracy for appropriateness for TKA compared to the OKS. A cross-sectional retrospective study of patients with knee OA attending a Regional Joint Assessment Program (RJAP) from January to September 2013 was conducted. Classification of appropriateness for TKA was determined by the attending orthopedic surgeon’s decision at the end of the assessment. Diagnostic accuracy for the OKS and the LEFS were determined using the area under the curve (AUC) of the receiver operator characteristic (ROC) curve. Cut-off scores were calculated for both outcome measures. Four hundred and twenty one patients eligible for the study (41.8% males; 66.9 years old) completed the OKS and the LEFS. The diagnostic accuracy for the OKS and the LEFS was determined using the AUC of the ROC curve for each patient-reported measure using Stata ® version 12.1. The cut-off scores were determined as the point on the ROC curve yielding the best sensitivity and specificity for the two outcome measures. The results showed the LEFS did not have higher diagnostic accuracy (LEFS AUC = 0.686 (95% CI = 0.636 – 0.736); OKS AUC = 0.674 (95% CI = 0.623- 0.724)) for determining appropriateness for TKA in patients with primary knee OA in isolation. The best cut-off score for those deemed appropriate for TKA among patients with knee OA was 26 out of 80 LEFS points and 42 points out of 60 OKS points. The results of this thesis agree with previous research reporting that decision-making regarding the need for TKA in patients with knee OA is multi-factorial. Our data confirm that this decision cannot be based on patient-reported physical function alone. Factors other than or in addition to patient-reported lower limb physical functioning should be considered when determining which patients with knee OA would most benefit from TKA. Further research evaluating these factors is warranted to improve triage services for patients with knee OA most likely to benefit from TKA. / Thesis / Master of Science Rehabilitation Science (MSc)

Background: Knee osteoarthritis (OA) is a prevalent disease that contributes to lower limb immobility and pain resulting in lost productivity in the work place. Repetitive loading of the knee joint, particularly in occupational settings, significantly increases OA risk. However, rest may promote tissue recovery and increase tissue tolerance to load. Therefore rest should be examined as a mechanism to prevent the development of knee OA. Purpose: The primary objective was to determine if rest can mitigate mechanical deformation of the stifle (knee) joint and articular cartilage damage during loading compared to an unloaded control in an intact porcine stifle model. Methods: A randomized controlled trial was conducted. Among 18 pairs of porcine hind limbs, one limb in each pair was randomly assigned to receive a loading intervention; while the matched pair served as control. Stifles in both groups were dissected, mounted into the loading apparatus, and pre-loaded. Intervention joints were then randomized into one of three loading protocols: no rest, 3:2 work:rest, and 1:1 work:rest; all of these protocols exposed joints to the same amount of cumulative load. Following loading, all joints were dissected to expose the cartilage. Cartilage damage was scored on a categorical scale. Deformation and energy dissipation were calculated for intervention limbs from data obtained from the loading apparatus. Results: Rest did not mitigate displacement or energy dissipation in the stifles exposed to loading. Rest was associated with reduced cartilage damage scores in the lateral femur in the 1:1 condition. Conclusion: Rest had little impact on joint mechanics and cartilage damage in this model. The small sample size may explain these results. Future investigations involving larger samples should assess if longer periods of rest are need to minimize joint damage as a result of loading. / Thesis / Master of Science (MSc) / Repetitive loading of the knee joint is linked to breakdown of knee cartilage leading to the development and progression of knee osteoarthritis (OA). For example, over-exposure to physically demanding tasks in the workplace (i.e. squatting, bending, lifting etc.) increases knee OA risk. However, it is possible that rest breaks can prevent cartilage damage by allowing the tissue to recover and maintain proper function. Therefore, the purpose of this work was to determine the influence of rest on knee joint mechanics and cartilage quality by repetitively loading pig knee joints and exposing them to varying periods of rest. Rest up to sixty seconds did not allow for tissue recovery, nor did it assist with joint function. This work suggests that longer periods of rest may be required to mitigate the damaging effects of loading, or that rest may not mitigate the effects of loading at all.

Osteoarthritis is the 12th leading cause of years lived with disability globally and by 2040 more than 10 million Canadians will have knee osteoarthritis (KOA). Pain in persons with KOA is well-recognized, persistent and chronic with central sensitization (CS) being prevalent in ~30%. CS is measured by psychophysical testing and patient-reported methods such as the Central Sensitization Inventory (CSI). The CSI was developed using subgroups of people with chronic pain, but not those with KOA. Therefore, validity of the CSI in people with KOA is lacking. CS as indicated by psychophysical tests is associated with CSI scores lower than the recommended cut score. Therefore, we aimed to evaluate the validity of the CSI through Rasch analysis in persons with KOA. We then sought to determine the agreement of the Rasch calibrated (RC-CSI) version of the CSI with the original and to evaluate the validity of the RC-CSI with psychophysical tests in people with KOA. In the first study, the CSI was able to fit Rasch model. After iterative analysis, we found the CSI to be a singular construct with acceptable unidimensionality while retaining all 25 items. Only two items - frequent urination (item 21) and Skin problems (item 19) showed a pattern of uniform differential item functioning by age and sex respectively. Moreover, we generated a RC-CSI cut score of 31.37 that we used to compare with the original cut score of 40. In second study, the findings suggested a lack of agreement between the two versions of the CSI demonstrating small bias. When exploring sensitivity and specificity with psychophysical tests, the RC-CSI showed little clinical value over the original CSI. We therefore recommend that the original CSI should be used with individual clients as our preliminary findings suggest that there is no added benefit to using the RC- CSI. / Thesis / Master of Science Rehabilitation Science (MSc)

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 37-41).

Trunk lean over the stance limb during gait has been linked to a reduction in the knee adduction moment, which is associated with joint loading. Differences were examined in knee adduction moments and frontal plane trunk lean during gait between subjects with knee osteoarthritis and a control group of healthy adults. Additionally, subject variability in human motion data presents a challenge to researchers when trying to detect differences between subject groups. The individual differences in neutral posture between subjects is a source of variation in joint angles. A method was developed using principal component analysis (PCA) to objectively reduce this inter subject variability. Gait analysis was performed on 80 subjects (40 osteoarthritis). Models were developed to define lateral thoracic tilt, as well as pelvic tilt. The trunk and pelvis frontal plane angles were used to describe trunk lean and pelvic tilt. Angles were calculated across the stance phase of gait. We analyzed the data, (i) by extracting discrete parameters (mean and peak) waveform values, and (ii) using principal component analysis (PCA) to extract shape and magnitude differences between the waveforms. Osteoarthritis (OA) subjects had a higher knee adduction moment than the control group (α=0.05). Although the discrete parameters for trunk lean did not show differences between groups, PCA did detect characteristic waveform differences between the control and osteoarthritis groups. The data show that subjects display similar waveform shapes, however waveforms vary in magnitude, suggesting a variation in posture between subjects. The results from the PCA reveal that the first PC, which captures the most variation in the data, represents this variation in magnitude. The second PC describes a significant difference in range of motion between the subject groups. Subjects with knee OA were found to have a different range of motion of their pelvis and trunk than control subjects. These changes are consistent with a strategy to lower the knee adduction moment. As an alternative to conventional subjective methods, PCA should be employed to reduce inter subject variability in order to ensure objective analysis in human motion waveform data. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-08-14 14:43:53.127

Thesis (MHSc--Health Science) -- AUT University, 2007. / Primary supervisor : Professor Peter McNair. Includes bibliographical references. Also held in print (xi, 147 leaves : col. ill. ; 30 cm.) in North Shore Campus Theses Collection (T 617.582 BRE)