Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaf 60. / by Susan Russell Stapleton. / B.S.

Orientador: Dirceu Barnabé Raveli / Banca: Arnaldo Pinzan / Banca: Ary dos Santos-Pinto / Resumo: O objetivo deste estudo cefalométrico foi avaliar as alterações no perfil facial decorrentes do crescimento natural e induzidas pelo uso do aparelho de Herbst no tratamento da má oclusão Classe II divisão 1 de Angle. A amostra foi constituída por dois grupos, com idades óssea e cronológica equivalentes, e, portanto, pertencentes aos estágios 1 e 2 de maturação esquelética (CVM). O grupo experimental foi constituído por 20 pacientes (12 meninos e 8 meninas), com média de idade inicial de 9,3 anos, que receberam tratamento com o aparelho de Herbst por 7 meses. O grupo controle foi constituído por 16 indivíduos (9 meninos e 7 meninas), com média de idade inicial de 9,1 anos, não tratados ortodonticamente e com características esqueléticas e dentárias semelhantes ao grupo experimental, derivados dos arquivos de documentações do Burlington Growth Centre da Faculdade de Odontologia, Universidade de Toronto, Canadá. Para avaliação das mudanças no perfil facial foram utilizadas telerradiografias em norma lateral iniciais e após 7 meses de tratamento no grupo experimental, e no grupo controle as radiografias foram tomadas anualmente e convertidas em 7 meses para efeitos de comparação. Os dados obtidos foram submetidos à análise estatística, realizada com teste t de Student, com nível de significância de 5%. Os resultados indicaram que o aparelho de Herbst promoveu uma redução significante da convexidade do perfil facial esquelético e de tecidos moles, aumento significante do ângulo mentolabial, além de demonstrar tendência à abertura do ângulo nasolabial. Alterações estatisticamente significantes como o aumento da altura facial anterior inferior, a retrusão do lábio superior e a protrusão do lábio inferior, assim como o aumento em comprimento deste, também foram observadas. Pode-se concluir que o uso do aparelho de Herbst induziu efeito favorável... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The purpose of this cephalometric study was to evaluate the facial profile changes due to natural growth and induced by the Herbst appliance on treatment of Angle's Class II division 1 malocclusion. The sample consisted of two groups, matched according to osseous and chronological ages, and therefore classified as stages 1 and 2 of skeletal maturity (CVM). The experimental group consisted of 20 patients (12 boys and 8 girls), initial mean age of 9.3 years, which were treated with the Herbst appliance for 7 months. The control group consisted of 16 individuals (9 boys and 7 girls), initial mean age of 9.1 years, not treated orthodontically and with skeletal and dental characteristics similar to the experimental group, originally from Burlington Growth Centre, Faculty of Dentistry, University of Toronto, Canada. For the analysis of facial profile changes, initial and 7-month treatment follow-up lateral cephalograms were obtained for the experimental group, and for the control group the radiographs were taken annually and converted to 7 months for comparison. The data obtained were submitted to statistical analysis, performed with Student's t test, at significance level of 5%. The results showed that the use of the Herbst appliance promoted a significant reduction of skeletal and soft tissue facial profile convexity, a significant increase of the mentolabial angle, as well as demonstrating tendency to open the nasolabial angle. Statistically significant alterations as the increase of the anterior facial height, the upper lip retrusion and lower lip protrusion, as well as the increase on its length, were also observed. It can be concluded that the Herbst appliance had a favorable effect on facial profile change, which became less convex, by acting mainly on the lips and the mentolabial areas. / Mestre

Proximal humerus fractures are the third most common fractures in the over-65 patient population and their stable fixation remains a key challenge in orthopaedic and trauma surgery. While Open Reduction Internal Fixation by plate has become a well-known treatment modality in the last few decades, clinical studies associate high complication rate with its use. The overall aim of this project was to create a computer-aided design framework for proximal humerus plates using a validated subject-specific humerus-plate finite element model. The framework consisted of three stages: (1) reverse engineering of bone and plate geometry, (2) creation and validation of a finite element model simulating the in vitro testing of the bone-implant construct and (3) parametric optimisation study of implant design using this model. In vitro biomechanical tests were conducted to not only compare the mechanical performance of three key commercially available proximal humerus plates (S3-, Fx- and PHILOS plate) but also the effect of different screw zones. Sixty-five humeri specimens with two-part surgical neck fractures were treated and grouped based on their different screw configurations. Extension, flexion, varus and valgus bending were applied in the cantilever fashion in the elastic tests whereas only varus bending was applied in the plastic tests. The load required to apply 5 mm displacement was measured to determine bone-plate construct stiffness. The S3 plate yielded the stiffest constructs and while the removal of the inferomedial support had the most impact on varus bending stiffness, type of medial support was important: inferomedial screws in the Fx plate achieved higher bending stiffness than blade insertion. Stability of constructs treated with the plate was an interplay of factors such as the plate’s and screws' number, orientation and position. Next, a subject-specific finite element model of the humerus-plate construct was successfully developed that simulated the stiffest of the constructs from the in vitro varus bending tests conducted in this project. The model was validated against the in vitro results. The validated model was then used to perform a parametric optimisation study where the combination of design parameters (height and divergence angle of S3 plate’s inferomedial screws) was determined that achieved optimum bone-plate construct stability (minimum fracture gap change). Out of the 538 designs tested, the optimum design (16o divergence angle and 33o height angle) yielded the lowest fracture gap change (0.156 mm) which was 4.686% lower than the standard finite element model while achieving 5.707% higher varus bending load (54.753 N). The validated model was also used to investigate the issue of using smooth pegs and threaded screws. Twenty-six models with different percentages of screw threading were run to compare their bone-plate construct stiffness. While threading the smooth pegs was found to increase the varus bending stiffness by up to 4.546%, it did not affect all screws equally. Finally, the successful completion of the optimisation study of screw orientation and the clinical investigation promises the implementation of the computational framework for a range of future multi-objective optimisation studies of multiple design parameters especially for the design of implants for other parts of the human body and also for investigations into other clinically relevant questions.

One out of 2 women and 1 out of 5 men over age 50 will sustain a fragility fracture (FF) in their lifetime. The risk of a 2nd FF increases dramatically after the 1st fracture and can lead to pain, disability, and mortality. Despite the evidence that secondary prevention programs are effective, the local facility did not have a formal mechanism to address this need. The purpose of this project was to design a program for secondary prevention of FFs and to address the need for a program for secondary FF prevention that was sustainable locally. The program was designed for facility patients age 50 or older who sustained a wrist fragility fracture within 6 months. The reach, effectiveness, adoption, implementation, maintenance (RE-AIM) framework was used to guide the project and program evaluation. A needs assessment was conducted prior to developing the program and included secondary data from the facility's provider survey. The 'Own the Bone' program, a nationally recognized program, was chosen as the intervention model. The 'Own the Bone' program provided a registry data for performance measures which assisted in the development of the program. The program included a short survey for providers to assess satisfaction with the referral process, and a telephone survey to referred patients who chose not to attend. Patient satisfaction with the program incorporated the Standardized Clinician Group Consumer Assessment of Healthcare Providers and Systems survey. Data collection and analysis plans were provided to the site with recommendations for implementation. This program was the 1st step in closing the local research-practice gap of secondary fragility fracture prevention. The project offers an opportunity to promote positive social change through the prevention of FF in a setting that had not previously addressed the problem.

Computational modeling in the field of biomechanics is becoming increasingly popular and successful in practice for its ability to predict function and provide information that would otherwise be unobtainable. Through the application of these new and constantly improving methods, kinematics and joint contact characteristics in pathological conditions of femoroacetabular impingement (FAI) and total hip arthroplasty (THA) were studied using a lower extremity computational model. Patients presenting with FAI exhibit abnormal contact between the femoral neck and acetabular rim leading to surrounding tissue damage in daily use. THA is the replacement of both the proximal femur and acetabular region of the pelvis and is the most common surgical intervention for degenerative hip disorders. A combination of rigid osteoarticular anatomy and force vectors representing soft tissue structures were used in developing this model. Kinematics produced by healthy models were formally validated with experimental data from Burnfield et al. This healthy model was then modified to emulate the desired morphology of FAI and a THA procedure with a range of combined version (CV) angles. All soft tissue structures were maintained constant for each subsequent model. Data gathered from these models did not provide any significant differences between the kinematics of healthy and FAI but did show a large amount of variation in all THA kinematics including incidents of dislocation with cases of lower CV angles. With the results of these computational studies performed with this model, an increased understanding of hip morphology with regards to STS has been achieved.

Cigarette smoking has been a public health concern for many years, and the possible impact of smoking on surgical site infection (SSI) has been studied broadly. However, a gap in understanding has persisted concerning whether there is an association between smoking tobacco and the development of SSI among patients who undergo lower extremity surgery, specifically total knee arthroplasty (TKA). The purpose of this study was to examine the association between smoking and lower extremity SSI. Andersen's behavioral model (BM) was used to understand the risk factors relevant to the interaction between smoking and SSI. Application of the BM categories of predisposing, enabling, need, and behavioral habits facilitated the discussion of surgical outcomes. A quantitative, cross-sectional approach was used to analyze data from a legacy registry of an east coast hospital. The research question addressed whether there was a relationship of the smoking status of three groups (i.e., smokers, nonsmokers, and previous smokers) and the variables in the BM categories (predisposing variables of age, gender, and body mass index [BMI]; enabling variable of health care insurance coverage; and need variables of health diagnoses, diabetes, hypertension, deficiency anemia, rheumatoid arthritis [RA]) to postoperative SSI. Multiple logistic regression test was used and no statistical association was found between smoking status and SSI; however, RA had a significant association with SSI. Positive social change may occur through the dissemination of new knowledge to reduce the financial burden of the prevalence of SSI through behavioral changes and improvements to health wellness.

Total ankle arthroplasties (TAAs) are mechanical devices used to replace the articular surfaces of the ankle joint in order to relieve pain for patients with osteoarthritis. Since most osteoarthritis is post-traumatic, and due to the highly variable individual foot geometry, TAAs are rarely inserted into normal geometry. This leads to serious problems with stresses and contact pressures in TAA components. This study uses finite element (FE) modeling to determine how hindfoot alignment, or how far in varus or valgus the most distal part of the calcaneus is perpendicularly from the axis of the tibia, affects the stresses and contact pressures in the articulating surfaces of two different TAA models. To investigate the effects of foot alignment on hardware stresses after TAA, FE models were generated. Models of the mobile bearing, three component Scandinavian Total Ankle Replacement (STAR) and the fixed bearing, two component Zimmer Trabecular Metal Total Ankle (Zimmer) were generated from laser scans of the hardware and virtually implanted into 3D models of the tibia and talus. Ligaments were modeled as linear springs to impart physiologically realistic flexibility in the model. The stance phase of a walking gait cycle was applied and stresses and contact pressures at the articulation between model components were recorded for various degrees of hindfoot alignment [1]. Data analyzed shows that both models have areas of high concentrations of stress and contact pressure. The Zimmer TAA seems to favor a valgus alignment due to the lower stresses and contact pressures in valgus alignments compared to varus. Though the STAR does not generally favor one alignment over the other, it does have significantly lower stresses and contact pressures than the Zimmer. These differences may be due to the geometric congruency of the STAR versus the anatomical articulation of the Zimmer.

Reverse shoulder arthroplasty (RSA) is performed to decrease pain and improve function and range of motion (ROM) primarily for patients with rotator cuff arthropathy, an arthritis of the shoulder secondary to rotator cuff insufficiency. However, RSA has suffered from high early to mid-term rates of complication, with instability being one of the most common. The shoulder biomechanics post-RSA depend on multiple factors such as implant geometry, positioning, and cuff integrity. This study built upon prior finite element (FE) analysis of RSA to investigate the effects of glenoid lateralization and retentive liner design on shoulder stability. A previously validated FE model was extended to model shoulder external rotation (ER) after implantation of the Zimmer Trabecular Metal RSA system. The FE model included the scapula bone with an implanted glenosphere implant, the humerus bone with implanted humeral sections of the RSA implant, and muscle tendons representing the subscapularis, infraspinatus, and deltoid. Six different models matched glenospheres in three cases of lateralization (2mm, 4mm, and 10mm) with two humeral poly liner designs (normal: 150° neck shaft angle or retentive: 155° neck shaft angle). Using Abaqus/Explicit FE software, the proximal ends of the soft tissues were pulled to their anatomical positions, and then fixed in space while the humerus was externally rotated 80° about the humeral long axis from a neutral position with the shoulder abducted 25°. The displacements, deltoid and subscapularis forces, impingement-free ROMs, and subluxation gap distances were recorded. Although greater glenosphere lateralization was associated with higher impingement-free ROM, larger deltoid and subscapularis forces developed. Deltoid tension contributes to shoulder stability and control, but elevated amounts of deltoid tension may contribute to scapular fractures and greater stress at impingement sites post-RSA. Further analysis such as inclusion of more anatomical features and additional motions may offer greater insight to orthopedic surgeons when planning for RSA insertion.

This study reviewed the methods of teaching orthopedics to family practice residents. It explored the areas of how, when, and to what end. Questionaires were sent to all family practice residency programs in the United States. The complied results showed that most residents are taught during a block assignment for four weeks in the second year of residency. The results showed preceptorships being utilized most frequently and for at least 50% of the teaching time. Lectures were used next most frequently and usually for 20% or less of the teaching time. Nearly all of the respondants felt their residents were qualified to initially manage athletic injuries, simple fractures, and low back pain. On the management of infant foot problems, 63% felt their residents were qualified and 36% felt they were not. This difference was felt to be due to a difference in content and not process. Suggestions for future research were put forth.Ball State UniversityMuncie, IN 47306

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