Abstract Introduction: The prevalence of anterior cruciate ligament tear is around 7000 every year within the swedish population and 95% of reconstructive surgery was with a hamstring tendon graft. Six months post surgery a 13% decrease in knee flexion strength compared to non injured side. The need for a study that determine the role of gastrocnemius and foot position in knee flexion is lacking in the litterature and could benefit Physiotheraphy ACL rehabilitation. Purpose: of his study was to investigate M gastrocnemius medialis (MGM) activation in the ipsilateral knee after removal of hamstring tendon for ACLR, and se if ankle position alter knee flexion outcomes. Method: 3 women, mean age 24 years who underwent ACL reconstruction with hamstring graft on one leg was tested. The time since injury was 3, 6 and 7 years respectively with an mean ,5 years wait until surgery. Isokinetic knee flexion and extension testing was done in the Biodex system 3 pro. EMG electrodes measured medial gastrocnemius activation with and without ankle in dorsiflexion. Results: Knee flexion peak strength was higher by a mean of 3 Nm (3,5%) with dorsiflexed foot. Mean (MGM) activation remained the same with or without dorsiflexion. Overall knee flexion strength was higher by a mean of 5 Nm compared to the injured side. Conclusion: Knee flexion in the biodex with foot in dorsiflexion could allow for isometric plantarflexion and increas power output. Certain changes in inclusion criteria and methodology as well more studies is needed to come to a given conclusion. / nej

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Introduction: Isokinetic testing is used in rehabilitation settings on a regular basis, yet there is a lack of consistency in rest period usage among protocols. Purpose: The purpose of this study was to establish an optimal rest period that would allow reproducibility of strength during a common isokinetic strength-test. Methods: Twentyseven healthy college-aged males underwent isokinetic strength testing to determine peak torque at 60, 180 and 300 deg/sec, respectively. Work:rest ratios of 1:3, 1:8 and 1:12 were counterbalanced between sets. A 3 X 3 repeated measures ANOVA was used to analyze the data. The p < .05 level of significance was used for all tests. Results: There was no significant difference in either knee extension or knee flexion peak torque when comparing work:rest ratios. Conclusion: These findings suggest that a 1:3 work:rest ratio is sufficient during a common isokinetic strength test.

Background: Sagittal plane external flexion moment in early stance has been reported to be both higher and lower in people with medial knee OA compared to control subjects. Purpose: Sagittal plane knee joint kinetics and kinematics were compared between people with medial compartment OA and healthy subjects. Subjects with OA and low pain scores were also compared to those with OA and moderate pain scores. Subjects: Forty people with medial knee OA and 40 age and sex matched control subjects. Method: Knee alignment and OA severity were measured from radiographs. Frontal and sagittal plane moments and knee flexion angle during gait were measured using a three dimensional motion analysis system and force plates. The Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) was used to measure pain; this score was used to divide the OA group into low pain and moderate pain OA groups. The relationship between knee flexion moment in early stance and gait speed, knee flexion angle and pain was also determined. Results: Subjects with OA had lower gait speed and cadence, and higher double limb support time. Peak knee adduction moment (first 50% of the gait cycle) was higher in the OA group. The knee flexion moment in early stance did not differ between groups; however the knee extension moment in late stance was lower in the knee OA group. The moderate pain group walked more slowly than the low pain group. The knee adduction moment, sagittal plane moments and knee flexion angle in stance did not differ between OA groups. A positive correlation was found between knee flexion moment and knee flexion angle in early stance in the knee OA group; the correlations between knee flexion moment and pain and gait speed were not significant. Conclusion: No differences were found in the knee flexion moment or stance phase knee flexion angle between the groups compared in this study, and therefore the results do not contribute to resolution of the controversy in the literature. Participants with knee OA in this study had relatively mild to moderate disease severity, which may have contributed to the non-significant findings. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2009-08-27 00:37:29.466

The purpose of this study was to examine the differences in technique between sprinters and baseball players while running at maximal speeds. 20 male NCAA Division I athletes participated; ten members of the track and field team specializing in the 100 m or 200 m sprint or the 100 m hurdles and ten members of the baseball team. Each subject performed a maximal effort 80 m sprint while their sprint times were recorded every 10 m starting at the 20 m mark. Each subject was filmed at they ran through a set10 m marking that included where they reached their top speed allowing the camera to capture at least one complete stride. By using the Peak Motus System, each subject's minimum knee flexion, minimum hip angle, knee extension at toe off, contact time, stride length, center of mass at touchdown and shank angle were measured. ANOVA with repeated measures found that sprinters and baseball players display significant differences in their sprinting technique in all variables except shank angle with the sprinters displaying a shorter 10 m split time. It was concluded that proper sprint training during baseball practice could prove to be beneficial to baseball players, however, further research would need to be conducted to support this claim.

Background: Knee osteoarthritis is a degenerative disease characterized by damaged joint tissues (e.g., cartilage) that leads to joint pain, and reduced mobility and quality of life. Various factors are involved in disease progression, including biomechanical, patient-reported outcome and mobility measures. This thesis provides important longitudinal data on the role of these factors in disease progression, and the trajectory of biomechanical factors in persons with knee osteoarthritis. Objectives: (1) Determine the extent to which changes over 2.5 years in knee cartilage thickness and volume in persons with knee osteoarthritis were predicted by the knee adduction and flexion moment peaks, and knee adduction moment impulse and loading frequency. (2) Determine the extent to which changes over 2 years in walking and stair-climbing mobility in women with knee osteoarthritis were predicted by quadriceps strength and power, pain and self-efficacy. (3) Estimate the relative and absolute test-retest reliabilities of biomechanical risk factors for knee osteoarthritis progression. Methods: Data were collected at 3-month intervals during a longitudinal (3-year), observational study of persons with clinical knee osteoarthritis (n=64). Magnetic resonance imaging of the study knee was acquired at the first and last assessments, and used to determine cartilage thickness and volume. Accelerometry and dynamometry data were acquired every 3 months, and used to determine knee loading frequency and knee muscle strength and power, respectively. Walking and stair-climbing mobility, as well as pain and self-efficacy data, were also collected every 3 months. Gait analyses were performed every 6 months, and used to calculate lower-extremity kinematics and kinetics. Results: (1) The knee adduction moment peak and impulse each interacted with body mass index to predict loss of medial tibial cartilage volume over 2.5 years. These interactions suggested that larger joint loads in those with a higher body mass index were associated with greater loss of cartilage volume. (2) In women, lower baseline self-efficacy predicted decreased walking and stair ascent performances over 2 years. Higher baseline pain intensity/frequency also predicted decreased walking performance. Quadriceps strength and power each interacted with self-efficacy to predict worsening stair ascent times. These interactions suggested that the impact of lesser quadriceps strength and power on worsening stair ascent performance was more important among women with lower self-efficacy. (3) Relative reliabilities were high for the knee adduction moment peak and impulse, quadriceps strength and power, and body mass index (i.e., intraclass correlation coefficients >0.80). Absolute reliabilities were high for quadriceps strength and body mass index (standard errors of measurement <15% of the mean). Data supported the use of interventions effective in reducing the knee adduction moment and body mass index, and increasing quadriceps strength, in persons with knee osteoarthritis. Conclusion: Findings from this thesis suggest that biomechanical factors play a modest independent role in the progression of knee osteoarthritis. However, in the presence of other circumstances (e.g., obesity, low self-efficacy, high pain intensity/frequency), biomechanical factors can vastly worsen the disease. Strategies aiming to curb structural progression and improve clinical outcomes in knee osteoarthritis should target biomechanical and clinical outcomes simultaneously. / Thesis / Doctor of Philosophy (PhD) / Knee osteoarthritis is a multifactorial disease whose progression involves worsening joint structure, symptoms, and mobility. Various factors are linked to the progression of this disease, including biomechanical, patient-reported outcome and mobility measures. This thesis provides important information on how these factors, separately and collectively, are involved in worsening disease over time, as well as benchmarks that are useful to clinicians and researchers in interpreting results from interventional or longitudinal research. First, we examined how different elements of knee loading were associated with changes in knee cartilage quantity over time in persons with knee osteoarthritis. Second, we examined how different elements of knee muscle capacity and patient-reported outcomes were related to changes in mobility over time in persons with knee osteoarthritis. Third, we examined the stability over time of various biomechanical risk factors for the progression of knee osteoarthritis. Novel results from this thesis showed that: (1) larger knee loads predicted cartilage loss over 2.5 years in obese individuals with knee osteoarthritis but not in persons of normal weight or overweight; (2) among women with knee osteoarthritis with lower self-efficacy (or confidence), lesser knee muscle capacity (strength, power) was an important predictor of declining stair-climbing performance over 2 years; and (3) clinical interventions that can positively alter knee biomechanics include weight loss, knee muscle strengthening, as well as specific knee surgery and alterations during walking to reduce knee loads. Interventions for knee osteoarthritis should target biomechanical and clinical outcomes simultaneously.