Mechanical Engineering - Theses
Permanent URI for this collection
Search Results
1 - 5 of 5
-
ItemEffect of lower-limb torsional deformities on muscle and joint function during gait( 2017)Torsional deformities of the femur and tibia have been associated with walking difficulties, lower-limb pain and joint dysfunction. Patients presenting with torsional deformities typically undergo medical imaging and 3D gait analysis, prior to consideration of surgical correction. To date, much of the research has focused on kinematic and kinetic deviations during gait. However, little is known in regards to the effect of torsional deformities on muscle and joint contact forces. The overall goal of this dissertation was to understand the effect of lower-limb torsional deformities on muscle and joint function during gait, to improve surgical decision-making and hence clinical outcomes. Prior to addressing the overall goal of this dissertation we investigated three key areas; 1) the evaluation of suitable clinical methods for the measurement of lower-limb torsion, 2) determining accurate anatomical based joint parameters (joint centres and axes) for the lower-limbs and 3) separating the effects of bone geometry (lower-limb torsion) and joint parameters on musculoskeletal modelling results (kinematics, kinetics, muscle-tendon unit lengths, muscle moment arms, muscle forces and joint contact forces). Various clinical methods of measuring lower-limb torsion were compared to the gold standard, computed tomography (CT) measurements. Physical examination measurements were unreliable, showing poor agreement with measurements from CT. Freehand 3D ultrasound and low dose biplanar radiography (EOS imaging) showed good agreement with measurements from CT. Validation of methods to determine joint centres and axes has been limited, often assessed with indirect outcome measures. For this study, patient-specific joint parameters were identified from low dose biplanar radiography and registered with respect to the skin markers used during 3D gait analysis. This was done for the hip joint centre, condylar axis (knee axis) and bimalleolar axis (ankle axis). This method was used as a reference to evaluate previously described methods. For the hip joint centre recent regression equations obtained from CT or magnetic resonance imaging showed good agreement with the reference, with the majority being less than 30mm from the reference. For the condylar axis both the conventional gait model and functional calibration methods were unreliable. Freehand 3D ultrasound imaging showed the closest results to the reference. The separate effects of bone geometry and joint parameters on the results from musculoskeletal modelling were investigated. Joint parameters had a significant effect on the kinematics, kinetics and hip and knee joint contact forces. Bone geometry had a significant effect on the muscle forces and hip and knee joint contact forces. Both bone geometry and joint parameters where deemed necessary inclusions in patient-specific musculoskeletal models. To address the overall goal of the dissertation we investigated the relationship between lower-limb torsional deformities, physical examination measures, gait parameters (kinematics, kinetics, muscle forces and joint contact forces) and pain in two clinical populations; children with idiopathic torsion and children with spastic diplegic cerebral palsy. This was done by creating musculoskeletal models with patient-specific anatomy, accurately registered to the skin markers used during 3D gait analysis. These models were created using low dose biplanar radiographs combined with 3D gait analysis. This investigation showed that both patients with idiopathic torsion and those with spastic cerebral palsy have similar gait deviations. However, the cerebral palsy patients showed additional gait deviations likely the result of muscle spasticity, muscle weakness and impaired selective motor control. Additionally, lower-limb torsion and joint contact forces were predictors of pain in both populations. This dissertation presents clinically feasible methods for the creation of musculoskeletal models on a patient-specific basis. This is the first study to combine low dose biplanar radiography with 3D gait analysis to obtain patient-specific musculoskeletal models. These models have the advantage of registering patient-specific anatomy with respect to the skin markers in a standing position, with short scan times (10 seconds) and low radiation exposure.
-
ItemEnhancement and evaluation of a mobile biplane X-ray imaging system( 2016)Accurate in vivo measurement of three-dimensional (3D) knee joint kinematics during locomotion is important for understanding knee joint function and for evaluating the performance of total knee arthroplasty (TKA) design and surgical procedures. The most accurate non-invasive method for measuring dynamic knee joint kinematics is biplane X-ray fluoroscopy. Current biplane fluoroscopy systems are stationary and impose restrictions on the measurement of joint kinematics during dynamic activity, making it necessary for subjects to walk on a treadmill, regardless of the potential differences in knee joint kinematics between treadmill and overground walking. In the Biomotion Laboratory at the University of Melbourne, a novel mobile biplane X-ray (MoBiX) imaging system was designed and built to track the knee and measure knee joint kinematics during overground walking. Prior to the present thesis, the MoBiX system was capable of translating the two X-ray units mounted on a custom robotic gantry mechanism to replicate predefined sagittal-plane knee trajectories during overground walking. The main objectives of the present thesis were threefold: first, to enable the MoBiX imaging system to track movement of the knee and calculate knee joint kinematics during overground walking; second, to establish the accuracy of knee joint kinematic measurements obtained from the MoBiX system; third, to acquire 3D knee joint kinematics for TKA patients for one complete cycle of overground walking and to quantify differences in knee joint kinematics between treadmill and overground walking. In the present thesis, methodologies as well as the associated hardware and software were developed and implemented to enhance the MoBiX imaging system. Specifically, a joint motion tracking system was developed to enable the MoBiX system to track and image the knee concurrently during overground walking. A four-step procedure was developed in accordance with methodologies commonly adopted in the literature to facilitate the extraction of knee joint kinematics from biplane X-ray images acquired by the MoBiX imaging system. Three benchmark experiments were designed and conducted to evaluate the accuracy with which the MoBiX imaging system measures 3D dynamic knee joint kinematics during overground walking. In vivo experiments were conducted on 10 TKA patients to acquire 3D knee joint kinematics during a complete cycle of overground walking, as well as to quantify the differences between treadmill and overground walking. Experimental results indicated that measurement accuracy was enhanced by tracking and imaging the knee concurrently during gait. Maximum RMS errors were 0.33 mm and 0.65°, respectively, for the relative translations and rotations between the tibial and femoral components of a TKA implant, and 0.78 mm and 0.77° for the relative translations and rotations between the tibia and femur in an intact knee. The 3D knee joint kinematics corresponding to treadmill walking did not closely represent overground walking, and significant differences were observed in the temporospatial gait parameters, 6DOF knee joint kinematics, articular joint contact and implant wear predictions.
-
ItemMusculoskeletal model for gait analysis in people with partial foot amputation( 2015)Partial foot amputation is the most common amputation performed in the world today. In Australia, over 74% of all lower limb amputations are partial foot amputations. Diabetic patients are 15 times more likely to have an amputation than people without diabetes. Despite the prevalence of partial foot amputation, the influence of different levels of amputation on the biomechanics of gait is not well understood. This research project aimed to develop subject-specific musculoskeletal models to simulate and analyse gait in people with partial foot amputation, including quantification of the forces developed in the lower limb muscles during walking. One subject with transmetatarsal amputation and another with metatarsophalangeal amputation were selected based on inclusion criteria. In the transmetatarsal subject, the effects of compromised metatarsals on spatiotemporal data, kinematics, kinetics and individual muscle forces were compared with those of a control subject with metatarsophalangeal amputation through toes. The validation of developed models showed that predicted joint angles and joint moments were comparable to those reported in another study so developed musculoskeletal models for subjects were used for individual muscle force prediction of lower limb muscles during stance. For some muscles, the timing of forces predicted by the models and the timing of their EMG data were comparable so the forces predicted for muscles were reliable so far. The results showed that once the metatarsals are compromised through transmetatarsal amputation, some gait abnormalities were observed. These changes in gait were caused by an inability to generate power across the ankle joint. In the residual limb with transmetatarsal amputation, the reduction in the magnitude of the net ankle joint moment was associated with the reduction in the calf muscle forces during terminal stance and pre-swing of the gait. Compromised metatarsals through transmetatarsal amputation may impair the biomechanics of gait significantly through the reduction in the capacity of calf muscle forces to plantar flex the ankle and generate the necessary ankle torque to propel the residual limb.
-
ItemPost-traumatic knee osteoarthritis after anterior cruciate ligament reconstruction: Psychological, functional and biomechanical factors and the effect of a targeted brace( 2015)Post-traumatic knee osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR) is prevalent in younger adults and has the potential to cause substantial knee-related symptoms and limit physical function. Physical and psychological impairments are likely to adversely affect quality of life and work participation. Knowledge of modifiable risk factors associated with knee OA post-ACLR has the greatest capacity to lead to new interventions that could change the natural history of knee OA. What are the modifiable factors associated with knee OA post-ACLR? Section A of this thesis describes the results of two cross-sectional studies which revealed that individuals with knee OA five to 12 years post-ACLR have worse knee confidence and greater kinesiophobia compared with individuals who have no OA five to 12 years post-ACLR. In individuals with knee OA five to 20 years post-ACLR, those with worse knee confidence have worse knee-related symptoms, poorer function, greater kinesiophobia, and poorer perceived self-efficacy and health-related quality of life. Section B of this thesis investigated knee biomechanics during walking in individuals post-ACLR. Pooled data from a systematic review revealed that, compared to healthy controls and uninjured contralateral knees, ACLR knees have abnormal knee biomechanics, particularly in the sagittal plane. Systematic review findings also revealed that the type of graft (hamstring or patellar) and time post-surgery could also influence knee biomechanics. A cross-sectional study also evaluated biomechanics in people with lateral knee OA post-ACLR. Compared to healthy controls, individuals with lateral knee OA five to 20 years post-ACLR had greater knee flexion and lower knee internal rotation angles, as well as greater pelvic anterior tilt, and hip flexion angles. Is there a potential intervention for modifiable risk factors associated with knee OA post-ACLR? A targeted knee brace was investigated for individuals with knee OA post-ACLR. First, a within-subject randomized study investigated the immediate and four-week effects of a targeted knee brace on knee-related symptoms and function in individuals with knee OA post-ACLR. The brace produced improvements in knee-related symptoms immediately and following four weeks of intervention. Second, a within-subject randomized study evaluated the immediate effects of varus bracing on gait characteristics in individuals with lateral knee OA post-ACLR. Results revealed that the unloader brace significantly altered gait characteristics associated with lateral knee OA post-ACLR. Overall, this thesis sheds light on some of the modifiable risk factors associated with knee OA post-ACLR, and investigated one targeted intervention with the potential to improve quality of life of individuals with knee OA post-ACLR. Targeting psychological, functional and biomechanical risk factors in individuals post-ACLR may aid in optimal recovery, and slowing disease progression in individuals with knee OA post-ACLR.
-
ItemLower-limb muscle forces and patellofemoral joint loading in people with and without patellofemoral osteoarthritis during walking and stair ambulation( 2012)Osteoarthritis (OA) is a chronic degenerative joint disease that is the leading cause of musculoskeletal pain and disability in Australia. OA often affects the knee joint and commonly occurs between the patella (knee cap) and femur (thigh bone), known as patellofemoral joint osteoarthritis (PFJ OA). PFJ OA is highly prevalent in elderly populations and is more common than tibiofemoral joint osteoarthritis (TFJ OA). Despite the differences in prevalence, PFJ OA is less studied than TFJ OA. The mechanical loading transferred through a joint is generally thought to play a major role in OA initiation and progression via the lifelong “wear and tear” of a joint’s articular cartilage. Alterations to gait patterns and muscle dysfunction are commonly observed in people with knee disorders. However, little is known on how these changes actually combine to alter patellofemoral joint (PFJ) loading. The use of computational models is becoming a popular approach to quantify in vivo muscle forces and joint contact forces in healthy individuals during common activities. However, these models have rarely been applied to pathological populations, such as PFJ OA. Given the dearth of knowledge in the gait characteristics, in vivo muscle function and PFJ joint loading in the PFJ OA population, the purpose of this study was to investigate the joint kinematics, joint moments, muscle forces and PFJ loading in individuals with and without PFJ OA during three common activities of daily life: (1) overground walking, (2) stair ascent and (3) stair descent. Four specific research questions are addressed in this thesis. 1. Do people with PFJ OA demonstrate altered trunk and lower-limb joint biomechanics in comparison to people without PFJ OA during walking and stair ambulation? 2. Do people with PFJ OA demonstrate differences in hip and knee muscle forces when compared to controls during walking and stair ambulation? 3. Is the patellofemoral joint reaction force different in people with and without PFJ OA during walking and stair ambulation? 4. Are there biomechanical characteristics that distinguish people with isolated PFJ OA from people with concurrent TFJ OA and PFJ OA? Quantitative gait experiments and computational modelling were utilised to address the above research questions. The main findings of this study were that subjects with PFJ OA (with and without concurrent TFJ OA) adopted activity-specific gait modifications to off-load the PFJ. Specifically, participants with PFJ OA chose to alter their sagittal-plane kinematics, such as increased anterior pelvic tilt and/or decreased knee flexion, during stair ambulation to reduce the knee extension moment, quadriceps force and the patellofemoral joint reaction force. PFJ OA participants also walked and descended stairs with lower hip abductor muscle forces and lower knee adduction moments, which may represent a frontal-plane adaptation to off-load the PFJ. The alterations in quadriceps and hip abductor muscle forces observed in the individuals with PFJ OA suggest that hip and knee muscle dysfunction may be characteristic features of the PFJ OA population. These findings indicate the importance of including the PFJ and the dynamics of joints proximal to the knee when investigating the knee OA disease process.