Knee osteoarthritis (OA) is a progressive disease and a leading cause of morbidity in older adults, resulting in severe mobility limitations. While the osteoligamentous and neuromuscular systems are altered in knee OA, little data is available to illustrate an association among these systems. The objective of this dissertation was to improve our understanding of how muscle activation patterns during gait are altered across the knee OA severity spectrum and to examine how factors related to the OA process are associated with these alterations. Three independent but related studies were conducted. Muscle activation of the medial and lateral orientations of the gastrocnemii, quadriceps and hamstrings were recorded during gait using surface electromyography for all three studies. Key activation features were identified using principal component analysis. First, participants selected from a large group (n=272) of individuals classified as asymptomatic, ii) moderate ii) severe knee OA were matched for walking velocity. Significant amplitude and temporal activation characteristics were found, supporting that differences among OA severities exist and were not the result of walking velocity only. Secondly, individuals with moderate OA were sub-grouped based on structural severity determined using Kellgren-Lawrence radiographic scores (II-IV) and were compared to a velocity-matched asymptomatic group. Medial gastrocnemius, lateral hamstring and quadriceps amplitudes and temporal patterns were significantly altered by structural severity where significant activation imbalances between the lateral:medial gastrocnemii and hamstrings were found with greater structural impairment (score>II). Thirdly, individuals with moderate OA were prospectively evaluated and divided into knee effusion and no effusion groups, based on a positive bulge test. A significantly higher knee flexion angle during mid-stance, higher quadriceps amplitudes and prolonged hamstrings amplitudes were found when effusion was found. These studies showed that muscle activation patterns during walking were related to i) OA presence and severity based on functional, symptoms and radiographic evidence, ii) structural severity and iii) knee joint effusion. These findings improve our understanding of the interrelationships between alterations in joint structure and function associated with knee OA and muscle activation patterns during gait. These data can contribute to the development of gait-based metrics that can facilitate knee OA diagnosis and monitor progression.

The progression of knee osteoarthritis (OA), the most common cause of physical disability in older adults, is influenced by muscular and biomechanical factors. Reliability of muscular and biomechanical measures, including knee muscle strength and limb alignment, is critical. Furthermore, conservative interventions that slow the course of OA disease progression and prevent disability are urgently needed. The objectives of this thesis were to: 1) investigate the reliability of measures of knee muscle strength and alignment in persons with knee OA, and 2) determine the influence of an exercise intervention targeting hip muscles on knee joint loading in those with medial knee OA. In the first study reliability of knee muscle strength measures was evaluated within one testing session in 40 persons with knee OA. Isometric and isokinetic peak torque values for the quadriceps and hamstring muscles demonstrated high degrees of intra-session reliability. Reliability of lower limb alignment measures was determined following a bone landmark-based approach with use of a computer program. Excellent reliability coefficients were found which compared favorably with reliability of manual measures from schematics of limb deformities drawn with AutoCAD® software. When the computer method was applied to 100 full-limb radiographs of persons with or at risk for knee OA, alignment measures demonstrated high inter- and intra-reader reliability. Hip muscle weakness may influence loading of the medial knee compartment. Hip abductor strength was evaluated in 40 individuals with medial compartment knee OA in comparison to a control group of 40 healthy older adults. The effect of an 8-week home-based hip abductor strengthening program on the knee adduction moment was also assessed in this group with knee OA, compared with the control group which received no intervention. Following the exercise program the OA group demonstrated improvements in hip abductor strength and functional performance on a sit-to-stand task. There were no changes in the knee adduction moment. Thus, hip muscle strengthening did not influence joint loading, but may improve function in persons with knee OA. Results from this thesis provide increased understanding of knee OA, from muscular and biomechanical perspectives, in the areas of measurement reliability and exercise intervention. / Thesis (Ph.D, Rehabilitation Science) -- Queen's University, 2008-09-25 01:29:13.675

Osteoarthritis (OA) is a group of diseases entailing degradation of joints, and has been designated as one of the key conditions for special attention during the World Health Organization’s Bone and Joint Decade (2000-2010) (Brooks & Hart, 2000). Research has demonstrated that body weight is the number one modifiable risk factor associated with the onset and progression of knee OA (Felson, 1996). However, exercise programs that aim to initiate weight loss and improve pain and function in knee OA often increase loading on the knee joint, contributing to degeneration of the knee and progression of the disease (Miyazaki et al, 2002). The introduction of a new anti-gravity treadmill, which utilizes a technology called Lower Body Positive Pressure (LBPP), allows the examination of the relationship between weight, knee pain and knee loading via knee acceleration during exercise. The null hypothesis states that there will be no significant difference in knee pain, knee function and knee joint acceleration when comparing full weight bearing and LBPP treadmill walking exercise in a young knee OA population. Twenty-two overweight/obese patients with mild or moderate early-onset knee OA were recruited to complete two 25 minute treadmill walking sessions (one full weight-bearing and one LBPP walking session) one week apart and two walkway walking sessions. Knee pain and knee acceleration were recorded. Paired t-tests and ANOVAs were used to compare conditions. On average, an LBPP of 12.3% body weight reduction reduced knee pain in our population. Knee pain was significantly lower during LBPP walking than during full weight-bearing walking. Knee acceleration decreased with increasing LBPP. Heel strike and toe-off data from walkway walking trials illustrated significantly different knee acceleration about the knee (slow walking loads were lower / fast walking were higher), as compared to treadmill walking sessions. This study illustrates that treadmill walking at a minimal level of LBPP can decrease knee pain and attenuate knee joint loads while allowing patients to complete exercise programs aimed at initiating weight loss and improving pain and function in knee OA. LBPP appears to be a promising tool for rehabilitation for those with painful knee OA and other lower body musculoskeletal conditions.

The purpose of this investigation was to evaluate and compare the efficacy of three functional knee braces in stabilizing anterior cruciate ligament (ACL) deficient knees. The subject sample consisted of eighteen males and females with a unilateral ACL deficiency. / The criterion variables consisted of the ability of each brace in controlling internal rotation and knee extension during active movement and knee extension during a high velocity activity (dynamic task). Total displacement of the knee brace during a running test was also evaluated. / The results of this study demonstrated significant differences between the efficacy of the three braces for control of knee extension during active movement, knee extension during a dynamic task and brace migration during a running task. There was no significant difference between the efficacy of the three braces in controlling internal rotation during active movement.

The primary purpose of this study was to determine the ratio of activation between the VMO and the VL during an open chain knee exercise (dynamic knee extension) and a closed chain knee exercise (lateral step-up). A secondary purpose of this study was to compare muscle activation during the concentric and eccentric phase of the exercises. The data obtained during the knee extension exercise was further analyzed to compare the activity of the VMO and VL during three ranges of knee flexion: 0° - 30°, 30° - 60°, and 60° - 90°. Electromyographic (EMG) data was collected while 20 Ball State University students, who were asymptomatic for Patellofemoral Pain Syndrome, performed the two selected exercises. A one way ANOVA showed no statistically significant difference between the VMO: VL ratio of the two exercises, but the lateral step-up did produce a ratio greater than 1.0. A one-way ANOVA indicated a significant difference between the RMS values of the VL for the concentric and eccentric phase of the knee extension exercise. Based on the results of this study, the lateral stepup and eccentric training could be used to selectively strengthen the VMO for the treatment of PFPS. / School of Physical Education

The purpose of this study is to investigate the relationship between oral contraceptive use and the musculo-tendinous stiffness of the knee flexors. Twenty-three female participants and ten male participants (control group) ranging in age from 20 - 30 years. A uniaxial accelerometer was used to assess stiffness based on the exponential decay of the damped oscillation. Female groups had estradiol and 17 a-OH progesterone levels tested. At 30% of MVC, the Ortho-Tri Cyclen group, the Other OC group and women not using OC's had a mean stiffness of 249.3+94.5, 274.1+79.1 and 216.0+43.3 Nm/rad respectively and at 50% of MVC values of 290.2+70.7, 326.7+78.9 and 267.9+52.6 Nm/rad respectively. No significant difference in stiffness was found. Also no correlation was found between estradiol and stiffness. These results indicate that there was no significance between knee stiffness and oral contraceptives within the female groups. / School of Physical Education, Sport, and Exercise Science

Osteoarthritis (OA) is a group of diseases entailing degradation of joints, and has been designated as one of the key conditions for special attention during the World Health Organization’s Bone and Joint Decade (2000-2010) (Brooks & Hart, 2000). Research has demonstrated that body weight is the number one modifiable risk factor associated with the onset and progression of knee OA (Felson, 1996). However, exercise programs that aim to initiate weight loss and improve pain and function in knee OA often increase loading on the knee joint, contributing to degeneration of the knee and progression of the disease (Miyazaki et al, 2002). The introduction of a new anti-gravity treadmill, which utilizes a technology called Lower Body Positive Pressure (LBPP), allows the examination of the relationship between weight, knee pain and knee loading via knee acceleration during exercise. The null hypothesis states that there will be no significant difference in knee pain, knee function and knee joint acceleration when comparing full weight bearing and LBPP treadmill walking exercise in a young knee OA population. Twenty-two overweight/obese patients with mild or moderate early-onset knee OA were recruited to complete two 25 minute treadmill walking sessions (one full weight-bearing and one LBPP walking session) one week apart and two walkway walking sessions. Knee pain and knee acceleration were recorded. Paired t-tests and ANOVAs were used to compare conditions. On average, an LBPP of 12.3% body weight reduction reduced knee pain in our population. Knee pain was significantly lower during LBPP walking than during full weight-bearing walking. Knee acceleration decreased with increasing LBPP. Heel strike and toe-off data from walkway walking trials illustrated significantly different knee acceleration about the knee (slow walking loads were lower / fast walking were higher), as compared to treadmill walking sessions. This study illustrates that treadmill walking at a minimal level of LBPP can decrease knee pain and attenuate knee joint loads while allowing patients to complete exercise programs aimed at initiating weight loss and improving pain and function in knee OA. LBPP appears to be a promising tool for rehabilitation for those with painful knee OA and other lower body musculoskeletal conditions.

The purpose of this investigation was to objectively evaluate whether three functional de-rotational knee braces stabilize an anterior cruciate ligament (ACL) deficiency. The subject sample consisted of fifteen males and females with a unilateral ACL deficiency. The data for each subject was obtained using the Genucom Knee Analyzer. A right knee-left knee anterior laxity difference of 3mm or greater served as a subject inclusion parameter for protocol completion. The inclusion criteria reduced the subject sample to a total of eleven. / The study consisted of a randomized block design. The experimental design consisted of three parts: (1) an investigation of translational stability, (2) an investigation of rotatory stability, and (3) a comparison between the three braces. / The analysis involved a one way ANOVA of the criterion variables; anterior laxity (ALAX), anterior midrange stiffness (AMRS), anterior endrange stiffness (AERS), internal laxity (ILAX), and translation of the lateral tibial plateau (TLTP). / The AMRS characteristics differed significantly (alpha = 0.05) at 20$ sp circ$ flexion. The results were the following: $-$10.00 $ pm$ 9.78 N/mm for brace 1, $-$2.86 $ pm$ 7.2 N/mm for brace 2 and $-$41.02 $ pm$ 14.79 N/mm for brace 3. The values evaluated for ALAX, AERS, ILAX, and TLTP profiles did not differ significantly between knee braces.

Thesis (MAppSc in Physiotherapy) -- University of South Australia, 1994

Thesis (MHlthSc(OccTh))--University of South Australia, 1999