The use of vibration as an exercise intervention offers new possibilities for coaches, clinicians, and strength and conditioning practitioners. It appears that muscle activation by means of vibration may induce improvements in strength and power similar to those observed with conventional strength training. Furthermore, vibration is thought to affect the neuromuscular functions that regulate muscle stiffness. There has been preponderance in the literature to assume that the stiffness properties of the muscle affect muscle function, which in turn affects functional performance. Improving functional performance is a major goal for recreational to elite athletes. However, improving the performance of well-trained athletes, especially whilst engaged in in-season training, is challenging, as the training status of such athletes is near optimal. Furthermore, training and playing schedules usually do not allow for adequate training frequencies. Therefore, the application of in-season vibration training may offer a means by which substantial loading can be placed upon the athlete with minimal interference to the weekly schedule. Consequently, the aims of this thesis were to: 1) determine the reliability of a new method to measure the stiffness of the knee extensor muscles; 2) investigate the relationship between knee extensor stiffness, strength, power, and speed; and 3) examine the effect six weeks of squat training with and without whole body vibration (WBV) has on knee extensor stiffness, strength, power, and speed.The reliability of a new method to measure the stiffness of the knee extensors was assessed. The within trial variation (coefficient of variation [CV] - 5.41-7.45%) for all five loads (30, 40, 50, 60, and 70% one-repetition-maximum [1RM]) and test-retest reliability (intra-class correlation coefficients [ICC] - 0.92-0.96) were deemed acceptable. Thirty semi-elite male rugby union players were assessed on sprint speed, squat strength, countermovement-jump (CMJ), and drop-jump (DJ) performance to investigate their relationships to knee extensor stiffness. Knee extensor stiffness was found to have no significant relationship to any of the functional performance measures (r = -0.16-0.17). On the basis of these findings it was suggested that the relationship of the knee extensor stiffness to functional performance was not significant (P>0.05). It was suggested that either the postural requirements of the test were inappropriate, or the knee extensor muscles were not the most suitable muscle group to measure.Immediately after the testing session described above, subjects began a six-week intervention of squat training with or without WBV. The percentage change over the six-week intervention for the stiffness and performance data were calculated and compared to determine if differences between training interventions were significant (P<0.05). The mean percentage change in knee extensor stiffness (average load of 30, 40, 50, 60, and 70% 1RM) for the squat only and squat vibration group were -4.18% and -6.59%, respectively. Non-significant mean percentage changes in squat strength (1.32 and -0.50%), CMJ height (-7.92 and -1.47%), DJ reactivity co-efficient (1.25 and -3.54%), and sprint times over 5, 10, and 20 m (range = -0.86 to -1.16% and 0.54 to -1.88%) were observed for the squat only and squat vibration groups, respectively. Squat training with and without WBV was capable of maintaining, but not improving knee extensor stiffness, strength, power, and speed during a six-week in-season training cycle.

Osteoarthritis and ageing have been shown to induce changes in the number and health of peripheral mechanoreceptors. Whilst position and movement awareness in the osteoarthritic knee have been studied extensively, little work to date has been produced on muscle force awareness in this subject group. Poor force acuity may contribute to muscle and joint pain and dysfunction, and additionally hinder rehabilitation efforts in an osteoarthritic population. Overestimation of the muscles forces required for a given task, resulting in greater joint compression forces, may aggravate and inflame osteoarthritic symptoms. Underestimation of required muscle forces may amplify existing joint instability, increasing the risk of injury in an osteoarthritic population. Additionally, both under and overloading of muscles during the rehabilitation process can delay the return to full function after injury.When regarding the neurological process of force coding, current debate centres on the relative importance of centrally generated motor command mediated 'sense of effort' versus the peripheral mechanoreceptor signalled 'sense of tension' as the dominant coding process, with central mechanisms favoured in the majority of studies published to date. The purpose of this study was to investigate muscle force awareness in the knee extensors and flexors and hands of subjects with and without knee joint osteoarthritis. Twenty one subjects with knee joint osteoarthritis and 23 age and gender matched subjects with no known knee pathology were evaluated. All subjects performed ipsilateral isometric force estimation and force matching tasks, at levels scaled to individual maximum voluntary capacity (MVC). Errors in estimation and matching acuity were normalised to reference targets (comparison force/reference force) giving a relative score (RS) to allow comparison across submaximal force levels with RS less than 1.0 indicating that subjects produced insufficient force and vice versa.Maximal voluntary capacity tests revealed significantly lower (p<0.05) peak knee extension torque (111.2 Nm versus 145.3 Nm), but similar peak knee flexion torque (46.1 Nm versus 45.4 Nm for osteoarthritis and control subjects respectively). A pattern of overestimation at low reference levels and underestimation at high reference levels was demonstrated by all subjects. In the lower limb, force appreciation differed significantly between muscle groups regardless of knee condition, with knee extensors demonstrating greater overall accuracy than knee flexors. There was a significant difference (p<0.05) in force estimation ability and a trend to significance (p=0.066) for force matching acuity across groups at the 10% MVC test level. A significant (p<0.05) group difference in grip force estimation ability between the lowest and highest target levels was demonstrated.It can be concluded that there are small differences in force acuity in osteoarthritis subjects at lower submaximal force targets when compared to healthy age matched peers. The notion of information redundancy, whereby no new proprioceptive inputs, regardless of origin, are able to effect an improvement in force acuity in a given situation has been demonstrated in previous studies that reported relatively stable force matching acuity at forces between 30% and 60% of maximal capacity. The poor comparative force perception demonstrated in this study by the osteoarthritis group at the lower submaximal test levels supports the notion that centrally generated copies of motor commands do not provide sufficient data to adequately encode force magnitude at low levels of force generation, evoking a greater reliance data received from peripheral mechanoreceptors. This has significant implications for this subject group given that the majority of daily tasks require only low levels of force generation. Given that perceptive acuity in a variety of sensory modalities has been shown to improve with training there may be a role for force perception training in older adults with osteoarthritis.

Passive knee motion is guided by the interaction of the articular surfaces and the restraining role of the soft-tissue structures. It is defined by characteristic kinematics within an envelope of motion. The main goal of this thesis was to simulate this characteristic motion by developing a subject-specific anatomically based finite element model. CT and MR image stacks were used to develop the geometry model and experimental (mechanical) test data was used as model input. Passive knee flexion was simulated and translational and rotational motion described using the Joint Coordinate System (JCS). The model was validated using clinical flexion and AP drawer tests. An ACL reconstruction model was also developed. Highest AP laxity was found at 30?? of flexion when the graft was positioned in the original native ACL insertion point. ACL tunnel positions were simulated according to surgical techniques. For this case, the highest AP laxity was displayed at 0?? of flexion. Four different graft materials were examined, with the quadriceps tendon graft exhibiting highest laxity, followed by the patellar tendon, braided hamstring and finally unbraided hamstring graft. The effect of malpositioning the graft's femoral attachment point from its central location was also investigated. The proximal femoral attachment point most closely mimicked the central attachment point in terms of AP laxity in the native ACL insertion group. In the ACL tunnel group, the posterior femoral attachment point most closely mimicked the intact knee. In this thesis it was found that changing the femoral insertion point of the graft can highly influence the AP laxity behaviour. Also using the surgical technique to create ACL tunnels may not necessarily produce the same kinematic behaviour as the intact knee. Lastly, this thesis has shown the importance of explicitly defining the local reference coordinate system when describing knee kinematics. Changing the coordinate system markedly alters the calculated kinematics. Ideally, a standardisation of local coordinate systems, similar to the JCS, would be proposed within the biomechanics community.

Attempts to understand the effects of ageing on the condition of a synovial joint. Knee joints of individuals with no known history of joint disease were examined and the pattern of cartilage damage was mapped macroscopically in a manner that allowed quantitation of the affected areas. / Bibliography: leaves 267-277. / vi, 277 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Pathology, 1993

Thesis (M.S.M.E.)--University of Delaware, 2006 / Principal faculty advisors: Sun, Jian-Qiao, Dept. of Mechanical Engineering; Katherine Rudolph, Dept. of Physical Therapy. Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Lynn Snyder-Mackler, Dept. of Physical Therapy. Includes bibliographical references.

In a world of war and turmoil in developing nations, land mines are becoming a concern, as millions of them are scattered in countries all over the world. Moreover, land mine prevention programs cannot clear land mine fields as fast as they are detonated each day. As a result, there are thousands that fall victim each year. There is immense demand for newer technologies to replace the aging prostheses used in these war torn nations. The active prosthetic knee (APK) design project is a novel design that utilizes simple, robust one degree of freedom (DOF) mechanics, while providing fully active knee torque control. The APK utilizes a high-speed brushed servomotor, providing the necessary torque and dynamics to provide the necessary gait characteristics of human locomotion. The main research contributions of this thesis are: 1) the mechanics and 2) the intelligence of the APK. This thesis investigates and highlights the prosthetic’s design process. The human biological system is studied and used as the design criteria when designing the device. Anthropometric data was used to determine the sizing and other physical properties. Moreover, Adaptive-Network-based Fuzzy-Interference Systems (ANFIS) and Fuzzy Interference Systems (FIS) are used to provide control to the APK. Finite element analysis (FEA) verifies the structural integrity of the APK. Four simulations are analyzed: equivalent stress, equivalent strain, shear stress and total deformation. These four simulations provide a mathematical interpretation of the physical system. We found that the first prototype, although a sound design, can be further improved to allow greater loading capabilities. Moreover, cyclical loading and total life cycles would also be significantly improved. A modular test stand is also designed and prototyped to allow APK testing. Since the APK prototype cannot be immediately placed on a human test subject, the test stand allows for experimentation in replicating human gait cycles.

The knee is one of the most complex joints in the body, relying entirely on ligaments and muscles for stabilization. With the rise in people participating in sports, including a significant increase in female athletes, the prevalence of anterior cruciate ligament (ACL) injuries is very evident. With recent research showing that ACL injuries lead to osteoarthritis 10-20 years after the injury, determining the cause of these injuries to be able to prevent them is crucial. To date, both in-vivo and in-vitro techniques have been used to analyze the influences of the ACL injury including neuromuscular, anatomical, and kinematic. In-vivo techniques used to investigate knee kinematics is limited by the inability to take real ACL strain measurements while in-vitro techniques used to investigate anatomical considerations is limited by the inability to apply true muscular and kinematic forces. The purpose of the present thesis is to show the design and validation of a dynamic knee injury simulator. The simulator puts a cadaver knee, original ligaments and patellar tendon still attached, through motions which put the ACL at a high-risk of injury with realistic influence of muscles. The muscular influences are applied with actuators pulling the same force pro les as natural muscles. To get realistic muscle pro files, Anybody Software is used. Anybody Software is a modeling software which puts a skeletal system through prescribed motions and using an optimization algorithm calculates the muscle force pro file. The motion of the knee in the sagittal plane is simulated with actuators. The simulator consists of four actuators which are used in force control mode to add the muscle influence to the knee. Another two belt actuators are used for the joint motions, one each for the hip and ankle. The hip will move along the resultant Z motion and the ankle will move along the resultant Y motion. Simple gait is used for initial validation, the actuators chosen have speed and force capabilities for high-risk motions. The gait was successfully simulated and muscle force versus time profi le tracked the input well. The regression coeffcient study shows very good comparison. The hamstring muscle group is the only one which does not show very good comparison however this is only due to the jumpy nature of the hamstring profi le. The ACL strain fell within a similar range to published gait ACL strain data. The validation was successful, and with greater available force and speeds in the actuators, showing the use of this simulator during high-risk motions is possible.

Chronic painful tendinopathy is a common cause for elite- and recreational athletes to stop or decrease the level of their sports activity. Recent research on innervation patterns, histopathology and possible pain mechanisms in tendons has led to an increased knowledge about the chronic painful tendon. Ultrasound (US) and colourDoppler (CD) examination showing localized high blood flow, inside and outside regions with structural tendon abnormalities, has been shown to be of importance for tendon pain. Immuno-histochemical analyses of biopsies have shown sensory and sympathetic nerves in close relation to the high blood flow outside the tendon. These findings have led to new ideas about development of new treatment methods for chronic painful tendinopathy. In study I, we evaluated the already in use, US-guided sclerosing polidocanol injection treatment of midportion Achilles tendinopathy, using two different concentrations of the substance. This study aimed to find out if there was a faster return to pain-free activity by using the concentration 10 mg/ml compared to the formerly used 5 mg/ml. There were no significant differences in the clinical results between the groups. In study II - Technical note, we aimed to develop a new one-stage surgical treatment method for patellar tendinopathy. This method was based on research concerning the innervation patterns and US and CD findings in patellar tendinopathy/ “jumper’s knee”. Technically we added ultrasound guidance to knee arthroscopy to identify and visualize the region of interest during a surgical shaving procedure. In study III, we tested the newly invented US and CD-guided arthroscopic shaving technique in a pilot study. The short-term clinical results were promising and the majority of the patients returned to pain-free activity after a short rehabilitation period. In study IV, we compared the US and CD-guided artrhroscopic shaving method with the already in use sclerosing polidocanol injection treatment in a randomized study. At short-term follow-up, the patients treated with US and CD-guided arthroscopic shaving had significantly less pain during rest and activity, were significantly more satisfied with the treatment, and had a faster return to sports, compared to the patients in the sclerosing injection group. There were no complications. In study V, at longer-term followup (endpoint 46 months) there was a significant decrease in pain during activity in both groups. There were no remaining significant differences in the pain levels during activity between the groups. The tendon structure had improved significantly in both groups. There was a significant decrease in the antero-posterior thickness of the proximal patellar tendon in patients treated with US and CD-guided arthroscopic shaving, but not in the sclerosing injection group. The CD flow had diminished significantly in both groups, and there was a correlation between low CD flow and high patient satisfaction in both groups, The CD flow decreased faster in the surgical group than in the injection group. In conclusion, this newly invented US and CD-guided arthroscopic shaving treatment, focusing on treatment outside the tendon, has shown good clinical results with pain relief and a fast return to sports activity, in patients with patellar tendinopathy.

In a world of war and turmoil in developing nations, land mines are becoming a concern, as millions of them are scattered in countries all over the world. Moreover, land mine prevention programs cannot clear land mine fields as fast as they are detonated each day. As a result, there are thousands that fall victim each year. There is immense demand for newer technologies to replace the aging prostheses used in these war torn nations. The active prosthetic knee (APK) design project is a novel design that utilizes simple, robust one degree of freedom (DOF) mechanics, while providing fully active knee torque control. The APK utilizes a high-speed brushed servomotor, providing the necessary torque and dynamics to provide the necessary gait characteristics of human locomotion. The main research contributions of this thesis are: 1) the mechanics and 2) the intelligence of the APK. This thesis investigates and highlights the prosthetic’s design process. The human biological system is studied and used as the design criteria when designing the device. Anthropometric data was used to determine the sizing and other physical properties. Moreover, Adaptive-Network-based Fuzzy-Interference Systems (ANFIS) and Fuzzy Interference Systems (FIS) are used to provide control to the APK. Finite element analysis (FEA) verifies the structural integrity of the APK. Four simulations are analyzed: equivalent stress, equivalent strain, shear stress and total deformation. These four simulations provide a mathematical interpretation of the physical system. We found that the first prototype, although a sound design, can be further improved to allow greater loading capabilities. Moreover, cyclical loading and total life cycles would also be significantly improved. A modular test stand is also designed and prototyped to allow APK testing. Since the APK prototype cannot be immediately placed on a human test subject, the test stand allows for experimentation in replicating human gait cycles.