A Biomodeling Investigation of Bracing on Clubfoot Children Treated by the Method of Ponseti

Congenital talipes equinovarus (clubfoot) is a complex deformity occurring in otherwise normal children. It presents in utero bilaterally or unilaterally with the affected feet turned inward. Clubfoot is the most common congenital musculoskeletal birth defect, with an annual worldwide occurrence of 150,000-200,000. Regardless of treatment, whether surgical or conservative, clubfoot has a stubborn tendency to relapse, thus requiring post-correction bracing. While newborn treatment lasts weeks, brace wear is often maintained to five years of age. To date, there are no investigations specifically focused on clubfoot bracing from an engineering perspective. This dissertation applies engineering principles to the condition; concluding that surrogate biomodeling is an accurate and repeatable method to investigate clubfoot bracing. Results show standard-of-care brace parameters (external rotation, width, and dorsiflexion) impact muscle-tendon tension. Increasing external rotation from 0-80 degrees results in a range of tension increase of 12%-18% in the gastrocnemius medial head, 22%-26% in the lateral head, 10%-16% in the soleus, and 0%-13% in the tibialis posterior. The range of tension increase when decreasing brace width from 4-inches greater to 4-inches less than shoulder width is 11%-29% for the medial head, 10%-28% for the lateral head, 4%-25% for the soleus, and 8%-18% for the tibialis posterior. The range of tension increase when increasing brace dorsiflexion from 0-30 degrees is 27%-44% for the medial head, 24%-50% for the lateral head, 19%-32% for the soleus, and 13%-23% for the tibialis posterior. Comparing brace options, such as articulating and standard-of-care braces, produces unique tension characteristics. The results indicate that external rotation and width parameters serve to enable the dorsiflexion parameter. The standard-of-care is the only investigated-brace containing all three parameters. Limitations in effectiveness are observed for brace options that do not have all three parameters, such as the articulating brace, with no ability to set dorsiflexion. It is concluded that surrogate biomodeling is an effective method to evaluate wide ranging brace options, and may potentially be used to assist in future clubfoot brace development. The surrogate biomodel may be used to impact patient care by tuning brace parameters to maximize benefit and minimize over-correction

Geometric Variances in Hip Osteoarthritis and Tribology of the Natural Hip

Osteoarthritis (OA) of the hip joint is a common form of arthritis that often requires surgical intervention using total hip replacement (THR), as treatment using early interventional techniques is still poorly understood. It is hoped that gaining a better understanding of hip geometry, and that using this information in future in-vitro simulations, will contribute to the evidence base regarding the aetiology of OA and the use of early surgical interventions to prevent or delay the onset of hip OA. This thesis aimed to investigate geometric variations in patients with known hip OA and compare them to asymptomatic participants of the same age. The thesis also aimed to develop a novel in-vitro simulation model for the tribological testing of complete natural hip joints. Twenty nine participants were recruited into the study (n=15 control and n=14 hip OA), and the geometry of their hip joints was explored and compared using high resolution (3.0 T) MRI and 3D shape matching software (EndPoint), which in the main, had previously been used for investigating the knee joint. In the study group, obvious shape differences such as superior flattening of the femoral head, differences in the sphericity of the head and acetabulum, and a significantly smaller degree of acetabular anteversion were observed when compared to the asymptomatic group. Experimental work began by validating a new pendulum friction simulator (Mk B) using THR bearings and hemiarthroplasties. One major modification and several minor modifications were required before the simulator could be used to develop the novel complete natural hip joint in-vitro simulation model, which was done successfully using porcine tissue. This model and the novel sample potting methodology developed alongside it can be used in future in-vitro tribological studies of the natural hip joint, and information gained from the MRI study can be used as geometric parameters for future in-vitro simulations

Characterizing the Variability of Kinematic Outcome Measures and Compensatory Movements using Inertial Measurement Units

Cost-effective wearable sensors to measure movement have gained traction as research and clinical tools. The potential to quantify movement with a portable and inexpensive way could provide benefits to patient populations (e.g. amputees) to supplement or replace current clinical evaluations. For example, characterization of frontal plane kinematic outcome measures is a relevant movement pattern to a complex amputee population. The ability to capture such movements could have important therapeutic opportunities. The current research worked towards characterizing frontal plane compensatory movement patterns with kinematic outcome measures described by inertial measurement units (IMU) data in healthy adults. This was an initial step towards developing a future toolkit that could characterize normal and aberrant movement patterns in clinical populations. The thesis is comprised of two related studies. The first study set out to evaluate the numerical accuracy of IMU estimated spatial measures when compared to a gold standard system. Six subjects completed six different movement tasks while instrumented with optical motion capture and IMUs. Each movement task probed the accuracy of specific deviations (e.g. vertical deviation). The hypothesis was that outcome measures would be strongly associated (r>0.8) and mean error would not be significantly different from zero and the coefficient of repeatability would be within priori set limits of agreement (±18 mm). Kinematic outcome measures had small mean error bias compared to gold standard measures and range of subject specific mean errors showed minimal differences. Task specific differences were evident when movement patterns exhibit large transverse rotations. These results showed the devices have a level of accuracy that may be suitable to characterize changes in movement patterns clinically. The second study aimed to utilize the same techniques from study 1 to describe compensatory kinematic outcome measures during a clinical obstacle avoidance task to differentiate between compensatory and normal movement patterns. Twelve subjects wore IMUs bilaterally on the ankles and on the belt above the right hip. An off the shelf orthotic knee brace was used to restrict lower limb knee joint kinematics (reduce range of motion). Participants completed 15 walking trials for three different brace conditions (No Brace, Unlocked Brace, Locked Brace) and two obstacle task conditions (Level Ground Walking and Obstacle Avoidance) to elicit a comparison of normal and compensatory movements. During the walking task, IMUs were able to characterize compensatory movements typical of the amputee population. Lateral deviation of the swinging foot was significantly larger during obstacle crossing with a locked brace compared to no brace. Maximum elevation of the limb was significantly larger while crossing obstacles compared to level ground walking and was precise enough to discern elevation differences of No Brace elevation from both Unlocked and Locked Brace conditions. Hip hiking was also significantly larger in the locked brace obstacle crossing from no brace obstacle crossing. Swing time was longer when the limb was braced and during obstacle crossing when compared to level ground walking. Healthy subjects had no significant changes to double support time compared those exhibited by amputees during walking. Overall, differences between IMU and gold standard measures are present. Mean error differences are present for certain tasks and criteria for agreeability between devices is not satisfied. Descriptive analysis of low subject mean error ranges across the majority of tasks indicate a potential utility in these measures to distinguish between movement patterns. During the clinical task, when knee mobility was manipulated compensatory movements were significantly different across conditions. This study provides evidence for the utility of IMU devices to support clinical gait analysis with quantifiable measures

An intelligent interactive segmentation method for the joint space in osteoarthritic ankles

Clinical reality is full of complex images that cannot be segmented automatically with current computer vision technology, requiring intensive user intervention. In [1] and [2] we proposed a framework for the systematic development of intelligent interactive segmentation techniques that aim at repeatable and predictable results obtained via efficient interaction. In this paper we apply this framework to segment the joint space boundary of osteoarthritic ankles. The solution is based on a heterogeneous boundary representation implemented with a new piecewise deformable model. User intervention is necessary only when this model fails, being performed via specialized interactive tools. Results obtained by a non-medical user are presented, indicating improvement over the manual practice in terms of accuracy and repeatability

An intelligent interactive segmentation method for the joint space in osteoarthritic ankles

Clinical reality is full of complex images that cannot be segmented automatically with current computer vision technology, requiring intensive user intervention. In [1] and [2] we proposed a framework for the systematic development of intelligent interactive segmentation techniques that aim at repeatable and predictable results obtained via efficient interaction. In this paper we apply this framework to segment the joint space boundary of osteoarthritic ankles. The solution is based on a heterogeneous boundary representation implemented with a new piecewise deformable model. User intervention is necessary only when this model fails, being performed via specialized interactive tools. Results obtained by a non-medical user are presented, indicating improvement over the manual practice in terms of accuracy and repeatabilit