No description available.

Studies have shown that the alignment of the knee in the coronal plane has a significant effect on the joint contact stress. However, gait analysis demonstrated that factors other than alignment contributed significantly to the outcome of corrective surgery. It was therefore hypothesized that muscle contraction can alter the stress distribution within the knee joint and that overloading can occur in the absence of a deformity. Six normal knees were harvested from different donors. The exact orientation of all muscle groups was recorded and their tendinous insertions carefully preserved. Custom built pressure transducers (6 per compartment, 0.5 mm thick, 10 mm diameter) were inserted through 2 small, posterior, capsular incisions and placed on the tibial surface and the menisci. The knees were mounted in a loading system which allowed free self-alignment of the joint under load. All muscles were replaced by wire cables instrumented with force transducer, tensioner and grip. Several alignment models (5, 10 degree varus, neutral, 5 degree valgus and 15 degree of flexion) as well as the effect of contraction of all major muscles crossing the knee joint were tested. An even pressure distribution was seen in neutral alignment. In a varus deformity the peak pressure shifted medially and laterally in valgus. Unloading of the opposite compartment was seen for deformities as small as 5 degrees. A flexion deformity produced a postero-lateral shift of the peak pressure area. Muscle contraction increased the pressure significantly in a region next to the muscle. Generally, unloading - though less significant - was seen in a region diagonally across the joint. These results suggest that muscular hyperactivity may considerable increase the contact stresses. However, muscle weakness or lack of muscular contraction may indirectly play a significant role in affecting the contact pressure distribution. If the muscle force is insufficient to counterbalance the external moment condylar lift-off occurs. This increases the angulation between femur and tibia thereby overloading the compartment where contact takes place; One can therefore conclude that abnormal gait patterns or neuromuscular control mechanisms may result in unphysiologically high contact stresses which may cause the development of unicompartmental osteoarthritis and subsequently, a deformity.

No description available.

Introduction: Rugby is a professional sport which places emphasises on strength, power, speed and endurance. Therefore the accurate assessment of rugby performance is very important for sports and exercise therapists to enable peak performance for the players. Lower limb strength is often tested by means of isokinetic testing, whilst functional power is tested by means of the vertical jump test. Sophisticated equipment used in the measurement of performance indicators, are often not available in smaller communities and rural areas. A good correlation between laboratory testing and functional testing could be of great value for determining performance in less fortunate communities. Aim of Study: To determine the relationship between isokinetic strength testing of the quadriceps and hamstring muscle groups and vertical jump performance in rugby players. Methods: Fifty one male, rugby players who were part of the Varsity Cup Tournament in (2011) participated in this study. Ethical approval was given by the Human Research Ethics Committee (HREC) of the University of Witwatersrand. Height and weight were measured. Isokinetic knee extensor and flexor strength was tested (Biodex system 4 dynamometer TM ) at 60˚/sec (5 repetitions), 180˚/sec (10 repetitions) and 300˚/sec (15 repetitions). A single leg vertical jump was done using the Vertec and the performance was assessed as maximal height jump in centimetres. Descriptive statistics (mean and standard deviation) are reported for all outcomes. The SPSS software (IBM. SPSS version 21) was used for analysis. A Pearson's Product Moment Correlation coefficient was calculated between the isokinetic parameters of quadriceps and hamstring muscles and the vertical jump height and power (watts). An independent t-test and a paired t-test were used to calculate the differences between the forward and backline players and the dominant (Dom) and non-dominant (ND) legs. Results: The mean age of the participants was 21.4 ± 1.2 years; they were 1.83 ± 7.4m tall and weighed 99.3 ± 13.8kg. There were 26 forward players (mean height of 1.88 ± 7.2m and mean weight of 109.9 ± 10.3kg) and 25 backline players (mean height of 1.80 ± 5.5m and mean weight of 88.3 ± 6.1kg). The forwards were significantly taller and heavier than the backline players (p = 0.0001). The forwards produced significant greater peak power in the vertical jump than the backline players in both the dominant and non-dominant legs (p=0.0001). The PT (Nm) decreased as the angular velocity increased from 60˚/sec to 300˚/sec. A significant negative correlation (r = - 0.313; p = 0.025) between peak torque (PT) concentric strength from the hamstrings at 60º/sec and the vertical jump height on the non-dominant side were found. Quadriceps PT to vertical power at the higher velocities showed significant correlations at 180º/sec (dominant: r = 0.294; p = 0.011) and 300º/sec (dominant: r = 0.352; p = 0.011; non-dominant: r = 0.293; p = 0.037). No significant correlations were found between peak torque and vertical jump height when corrected for body weight. When correlating PT and vertical jump power corrected for body weight significant negative correlations was found at 180º/sec (dominant: r = 0.319; p = 0.022; non-dominant: r = 0.305; p = 0.030) for the hamstrings. Conclusion: The findings from the presented study found no significant correlation between lower limb isokinetic knee muscle torque parameters and vertical jump performance in rugby union players. Future research should investigate the relationship between isokinetic testing and vertical jump height by including the parameters of a multi joint mechanism.

One of the most poorly understood co-morbidities associated with obesity is the pathway to osteoarthritis of the knee. To implement appropriate preventative strategies, it is important to explore how obesity is a causal factor for osteoarthritis. The present research compared the kinematics and kinetics of a group of young obese, but otherwise healthy, adults to a group of young, healthy-weight adults, in an attempt to identify mechanical abnormalities at the knee during walking that may predispose the obese to osteoarthritis of the knee. Optotrak motion capture (Northern Digital Inc. Waterloo, Ontario) and a forceplate (AMTI OR6-7, Advanced Mechanical Technology Inc, Watertown, MA) were used to measure ground reaction forces and moments of 16 participants – 8 obese and 8 sex-, age- and height-matched healthy-weight – to analyze knee joint kinematics and kinetics at three walking speeds. Participants wore an accelerometer (ActiGraph GT3X, Fort Walton Beach, USA) for seven days to measure daily steps counts. Dependent t-tests were performed to determine group differences in ground reaction forces, knee angles and knee moments, as well as knee adduction moment impulse and cumulative knee adductor load (CKAL). The obese group walked at a significantly slower self-selected speed (p=0.013). While not statistically significant, the obese group did present with a more valgus mean dynamic knee alignment than the health-weight group. A significantly greater maximum abduction angle (p=0.009) and smaller minimum knee flexion angle at heel contact (p=0.001) was found in the obese group. A significant difference was found in the peak medial rotation moment in the transverse plane (p=0.003). A greater stance duration lead to a significantly greater knee adduction moment impulse (p=0.049) in the obese group. While significant group differences were not found in the steps per day, the obese group had a significantly greater CKAL (p=0.025). Obese young adults with healthy knees demonstrated a gait pattern of reduced medial knee joint compartment loading through greater knee abduction, medial knee rotation and a slower walking speed compared to matched controls. The ramifications of gait modifications on long-term musculoskeletal health remain unknown, but compensations may lead to increased risk of osteoarthritis of the knee.

The knee joint is the most commonly injured joint in the body. Clinical methods used at present for the diagnosis of cartilage pathology in the knee are invasive in nature. Analysis of vibration signals emitted by the knee joint has the potential for the development of a non-invasive procedure for the diagnosis of knee pathology. By Short Time Fourier Transform (STFT) and calculating root mean square (RMS) value, via One Way ANOVA at last, to demonstrate whether the two analysis methods are valid in this work. The method was tested on 14 male volunteers from NSYSU (7 players of in-line skating and 7 normal schoolmates). By analyzing the signals extracted from the players, finding difference of them, and distinguishing whether they are healthy. In conclusion, if the knee joint ligament is unusual, the frequency of signal is higher than 50 Hz; if not, the frequency is lower than 10 Hz. On the other hand, the RMS value of signal has no distinct region among the testers, so could not be used to analyze the signals. The results should be able to take as the reference for the diagnosis of knee joint non-invasively in clinical medicine.

One of the most poorly understood co-morbidities associated with obesity is the pathway to osteoarthritis of the knee. To implement appropriate preventative strategies, it is important to explore how obesity is a causal factor for osteoarthritis. The present research compared the kinematics and kinetics of a group of young obese, but otherwise healthy, adults to a group of young, healthy-weight adults, in an attempt to identify mechanical abnormalities at the knee during walking that may predispose the obese to osteoarthritis of the knee. Optotrak motion capture (Northern Digital Inc. Waterloo, Ontario) and a forceplate (AMTI OR6-7, Advanced Mechanical Technology Inc, Watertown, MA) were used to measure ground reaction forces and moments of 16 participants – 8 obese and 8 sex-, age- and height-matched healthy-weight – to analyze knee joint kinematics and kinetics at three walking speeds. Participants wore an accelerometer (ActiGraph GT3X, Fort Walton Beach, USA) for seven days to measure daily steps counts. Dependent t-tests were performed to determine group differences in ground reaction forces, knee angles and knee moments, as well as knee adduction moment impulse and cumulative knee adductor load (CKAL). The obese group walked at a significantly slower self-selected speed (p=0.013). While not statistically significant, the obese group did present with a more valgus mean dynamic knee alignment than the health-weight group. A significantly greater maximum abduction angle (p=0.009) and smaller minimum knee flexion angle at heel contact (p=0.001) was found in the obese group. A significant difference was found in the peak medial rotation moment in the transverse plane (p=0.003). A greater stance duration lead to a significantly greater knee adduction moment impulse (p=0.049) in the obese group. While significant group differences were not found in the steps per day, the obese group had a significantly greater CKAL (p=0.025). Obese young adults with healthy knees demonstrated a gait pattern of reduced medial knee joint compartment loading through greater knee abduction, medial knee rotation and a slower walking speed compared to matched controls. The ramifications of gait modifications on long-term musculoskeletal health remain unknown, but compensations may lead to increased risk of osteoarthritis of the knee.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (M.Ost.)--Unitec New Zealand, 2009. / Includes bibliographical references (leaves 24-28).

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.