published_or_final_version / Diagnostic Radiology / Master / Master of Philosophy

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

Epidemiological studies have identified kneeling as an occupational risk factor for knee joint osteoarthritis (KOA), but direct biomechanical evidence for this relationship is lacking. We hypothesize one mechanism by which prolonged static kneeling may cause KOA is by compromising the integrity of the knee joint thereby increasing knee joint instability, which manifests as altered ambulatory loading profiles. Therefore, the purpose of this exploratory study was to investigate the effect of sustained static kneeling on knee joint gait parameters. Ten healthy male subjects (24.1 years ± 3.5) volunteered for this study. Each subject’s dominant leg was instrumented with markers to track lower limb motion and with surface electromyography electrodes to record quadriceps, hamstrings, and gastrocnemius muscle activity. Subjects performed ten walking trials at a self-selected normal pace over a force plate embedded in the floor. They then performed a kneeling protocol of three bouts of ten minutes of kneeling, each separated by a five minute seated rest period. Subsequently, a set of ten walking trials were performed after a short rest and equipment verification period. The ground reaction force and motion data were used to calculate the peak knee adduction moments, knee flexion moments, and knee flexion angles during the stance phase. The total muscle activity for each muscle during a single gait cycle as well as the co-contraction of the medial thigh muscles and the lateral thigh muscles were calculated from the surface electromyography data. One-sample t-tests were run on the absolute value of the pre- and post-kneeling outcome measures. All outcome measures were different across conditions indicating that the loading patterns were altered, in no specific direction, as a result of the static kneeling protocol. These results offer preliminary evidence to support the epidemiological findings that thirty minutes of daily occupational kneeling is associated with a higher prevalence of KOA. Further investigation is required to explore the importance of post-kneeling recovery, posture-induced blood occlusion, and cartilage stress due to cumulative loading while kneeling, as well as to test the clinical significance of the present findings. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2008-08-11 23:30:10.708

Knee osteoarthritis is a disease that affects nearly 40% of the global population over the age of seventy. It is believed that the incidence and progression of osteoarthritis can be partially attributed to changes in mechanical joint loading. Consequently, changes in lower-limb joint moments are important outcome measures for its treatment and prevention. The purpose of this study was to investigate the effect of four different anatomic joint models on the detection of changes in lower-limb joint moments due to knee osteoarthritis. Moments during gait were calculated for 44 subjects with moderate osteoarthritis and 44 asymptomatic subjects, then expressed using four joint models: Joint Coordinate System, Plane of Progression, Distal, and Proximal. Discrete peak measures and principal component scores were compared between groups. Hip adduction magnitude, knee adduction magnitude, peak early-stance knee internal rotation, and peak ankle plantarflexion moments were different between groups regardless of joint model. Differences detected using principal component analysis were less sensitive to the choice of joint model. Results support adoption of the Joint Coordinate System as a standard for joint moment expression due to its clinical relevance and ability to detect differences due to moderate knee osteoarthritis. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-07-29 14:08:56.683

No description available.

Impact loads have been implicated in the initiation of secondary osteoarthritis but in the absence of defined injury this is difficult to rest rigorously.  The response to controlled impacts of samples of cartilage and bone in isolation and together, may yield valuable insights into how tissue properties may influence degenerative changes associated with osteoarthritis. A rigid instrumented drop tower was constructed and interfaced to a LabVIEW software oscilloscope modified to capture and store data to disk.  Controlled impact loads were applied to cores of articular cartilage, both isolated and in situ on the underlying bone or bonded to substrates of different material properties.  Bovine tissue from the carpometacarpal joint and human cartilage from elderly femoral heads was used.  The response of the samples was investigated in terms of a dynamic stiffness, energy absorbed and coefficient of restitution.  In addition the quasistatic modulus was measured from compression tests in order to compare the values for the stiffness of cartilage and bone at different rates of stress and strain.  Composition analysis was then performed on human cartilage samples to investigate if there was any correlation between the biochemical constituents and mechanical factors. The dynamic stiffness of the cartilage samples was governed by peak stress and did not show a high sensitivity to strain rate.  Cartilage had good force attenuating properties in situ on bone and the substrates.  The greater volume of the stiffer underlying substrate dominated the response of the composite samples.  For the human cartilage samples the dynamic stiffness was most correlated to percentage collagen whereas the quasistatic modulus was most correlated with water content.  Overall the biochemical composition was a poor predictor of stiffness which indicates the importance of interactions between the matrix constituents in the tissue response to an applied load.

Knee joint osteoarthritis is recognised as a significant subset of osteoarthritis. Little work has examined muscle changes that occur with knee joint osteoarthritis. Much of this work has centred on strength deficits, while little work has examined the effect of joint pathologies, such as osteoarthritis, on the fatigue resistance of the muscles associated with an affected joint. The purpose of this study was to investigate the relative fatigue-resistance characteristics of the vastus medialis in subjects with and without knee joint osteoarthritis, as well as the ability to predict endurance times in these groups, using high spatial resolution electromyography and a sub-maximal isometric endurance test. Twenty-six subjects with unilateral knee osteoarthritis and seventeen subjects with no known knee pathology were evaluated. All subjects performed initial tests to evaluate maximum voluntary contraction (MVC), voluntary activation levels, and true maximum force (TMF). Endurance time was assessed during an isometric quadriceps contraction at 50% of the true maximum force. Surface electromyography (sEMG) data was collected from the vastus medialis muscle of the quadriceps group during the endurance test. MVC tests showed that the affected leg of the group with osteoarthritis was significantly weaker (p < 0.05) than the unaffected leg. Voluntary activation data showed that subjects with osteoarthritis presented with significant bilateral deficits (p < 0.05). TMF data showed a significantly lower (p < 0.05) true potential for force generation in the affected compared to the unaffected leg of the osteoarthritis group. Endurance time data showed no significant difference between groups. Electromyography data showed significant differences (p < 0.05) between the affected and unaffected legs in initial values of Median Frequency (MDF), Mean Power Frequency (MPF) and Conduction Velocity (CV), the percentage change in CV and the relative rate of change in the frequency band between 5 and 30Hz (FB1). Finally, significant correlations were seen between endurance time and the relative rate of change of MDF, MPF and CV calculated over the initial thirty seconds of the endurance test. There were no significant correlations from either leg of the group with knee joint osteoarthritis.It can be concluded from this study that there are differences in strength measures, and in the sEMG signal collected from the vastus medialis muscle of the affected and unaffected legs of subjects with knee osteoarthritis. It appears likely that the differences observed in the sEMG signals were related to a decrease in the representation of type-2 muscle fibres in the vastus medialis of the affected leg. Furthermore, these changes in the behaviour of the signal appear to indicate an improvement in the relative fatigue resistance of the affected leg in relation to the unaffected leg of the group with knee osteoarthritis.Moderate success was seen with the prediction of endurance time in control subjects in the current work using a short duration (30-second) endurance test. This relationship was not seen in either the affected or unaffected leg of the subjects with knee osteoarthritis. Further investigation utilising different sEMG collection and analysis techniques in this area may improve prediction of endurance time in unaffected and affected subjects.

Universiẗat, Diss., 2006--Giessen.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.