Developmental dysplasia of the hip (DDH) refers to some hip disorders, from mildly dysplastic to hip joint dislocation. The main feature of DDH is the deficient acetabular coverage, which is related to a small contact area in the hip joint, and causes an increase in contact pressure. Ganz periacetabular osteotomy (PAO) is a surgical procedure to correct acetabular orientation in DDH. It changes the position of the acetabulum to increase the femoral head coverage and distribute the contact pressure over the cartilage surface. The procedure of Ganz PAO is technically demanding and its success depends significantly on the surgeon’s experience. The aim of this research is to investigate whether it is possible to optimize the position of the acetabular fragment in patients suffering DDH before a Ganz PAO by using finite element (FE) analysis. Using computed tomography (CT) data from patients with DDH, five three-dimensional (3D) hip models were developed. A virtual Ganz PAO was then performed on the hip models. FE analyses were carried out on the hip models before and after virtual Ganz PAO. Contact area, contact pressure and Von Mises stress in the hip cartilage were checked and analysed in order to find an optimal acetabular position. The first virtual surgery performed was only to rotate the acetabular fragment in the lateral direction to improve the acetabular coverage. Analyses were conducted under loading conditions associated with four commonly daily activities: one leg stance, normal walking, descending stairs and knee bend. Second virtual surgery performed was to rotate the fragment in both the lateral and anterior directions and FE analysis conducted for one leg stance loading condition. Contact area, contact pressure and Von Mises stress in the cartilage all varied according to the change of the acetabular fragment position through virtual Ganz PAO. The optimal lateral position of the acetabular fragment occurs close to the inferior border of its normal range. Large anterior position of the acetabular fragment results in large contact area, low contact pressure and Von Mises stress. However, an overcorrection of the acetabular fragment, especially in the anterior correction, leads to problems in performing normal hip movements. The optimal anterior position of the acetabular fragment is therefore close to the superior limit of the normal range. In conclusion, the present analysis shows that an optimal position of the acetabular fragment for patients suffering DDH which improves the acetabular femoral head coverage in the normal range, maximizes the contact area and minimizes the contact pressure and Von Mises stress can be established using 3D models and FE analysis. This information will be useful to the surgeons for the planning of PAO.

Developmental dysplasia of the hip (DDH) is a common newborn condition where the femoral head is not located in its natural position in the acetabulum (hip socket). Several treatment methods are being implemented worldwide to treat this abnormal condition. One of the most effective methods of treatment is the use of Pavlik Harness, which directs the femoral head toward the natural position inside the acetabulum. This dissertation presents a developed method for identifying the least energy path that the femoral head would follow during reduction. This is achieved by utilizing a validated computational biomechanical model that allows the determination of the potential energy, and then implementing the principle of stationary potential energy. The potential energy stems from strain energy stored in the muscles and gravitational potential energy of four rigid-body components of lower limb bones. Five muscles are identified and modeled because of their effect on DDH reduction. Clinical observations indicate that reduction with the Pavlik Harness occurs passively in deep sleep under the combined effects of gravity and the constraints of the Pavlik Harness. A non-linear constitutive equation, describing the passive muscle response, is used in the potential energy computation. Different DDH abnormalities with various flexion, abduction, and hip rotation angles are considered, and least energy paths are identified. Several constraints, such as geometry and harness configuration, are considered to closely simulate real cases of DDH. Results confirm the clinical observations of two different pathways for closed reduction. The path of least energy closely approximated the modified Hoffman-Daimler method. Release of the pectineus muscle favored a more direct pathway over the posterior rim of the acetabulum. The direct path over the posterior rim of the acetabulum requires more energy. This model supports the observation that Grade IV dislocations may require manual reduction by the direct path. However, the indirect path requires less energy and may be an alternative to direct manual reduction of Grade IV infantile hip dislocations. Of great importance, as a result of this work, identifying the minimum energy path that the femoral head would travel would provide a non-surgical tool that effectively aids the surgeon in treating DDH.

Orientador: Prof. Dr. Harki Tanaka / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Engenharia Biomédica, 2015. / A displasia do desenvolvimento do quadril é uma doença caracterizada por uma deformidade anatômica do quadril e pode acometer o recém nascido. O tratamento, um processo demorado, requer um diagnóstico precoce e uma intervenção ortopédica adequada, pelo uso do colete de Pavilik ou gesso pelvipodálico. Essas formas de tratamento podem apresentar complicações como: dor, aumento de temperatura corporal e necessidade de cuidado extra com a pele, entre outras. No presente estudo foi proposta uma metodologia para o desenvolvimento de um protótipo de órtese ortopédica de quadril infantil baseado no uso de três técnicas, fotogrametria, otimização topológica e prototipagem rápida. A fotogrametria foi utilizada para a obtenção da geometria da superfície do quadril de um modelo anatômico, de tamanho aproximado de um bebê, por meio de reconstrução tridimensional do quadril a partir de fotograas digitais. Para a avaliação da ecácia da técnica, a superfície obtida por fotogrametria foi comparada com geometria obtida por meio de um scanner a laser comercial. A diferença entre as topologias foi de 10 mm. A otimização topológica foi usada para maximizar a rigidez da órtese usando uma quantidade mínima de material. Protótipos iniciais da órtese de quadril infantil foram produzidos por prototipagem rápida para identicação de falhas e ajuste da órtese no modelo do bebê. Os resultados mostram que é possível, usando as técnicas de baixo custo, criar um protótipo de órtese leve e anatômico que possa ser posteriormente investigado com uma alternativa no tratamento de displasia do desenvolvimento do quadril a m de melhorar a qualidade de vida do recém-nascido e familiares. / The developmental dysplasia of the hip is a childhood disease characterized by an abnormal deformity that aects the hip. The treatment is a slow process and requires an early diagnostic to make a proper orthopedic intervention. By using a Pavilik harness or a hip spica cast, the actual treatment can cause complications such as pain, high body temperature, skin care diculties and others. In this project an orthoses prototype for a child hip was developed by using three dierent techniques; photogrammetry, topology optimization and rapid prototyping. The photogrammetry with tridimensional reconstruction from digital photographs was used to reconstruct the surface of an anatomical model of a child hip, which had approximately the size of a new born child.To evaluate the technique, the geometry captured by the photogrammetry was compared with the same geometry captured by a commercial laser scanner and the dierence between the two topologies was only of 10 mm. The topology optimization has been used with the objective of maximizing maximize the rigidity using the minimum quantity of material. Initial prototypes of the orthoses for a child hip, without the optimization, was produced by rapid prototyping in a small size scale and in a real scale to identify possible failures in the model, and in the coupling between prototype and anatomical model and to plan the fastening system. The results show that is possible to use low cost techniques to create a light and anatomical prototype that can be used as an alternative treatment to the developmental dysplasia of the hip. It can eventually improve the life quality of the child and family.

Introduction Developmental dysplasia of the hip has since 1953 in Sweden most commonly been treated with the von Rosen splint. Over time, different types of splints have been developed, one of which is the Orebro splint. In some countries it is advised to have long-term follow-ups with radiological exams of patients treated with a splint. In Orebro, there is currently no mandatory follow-up after treatment with the Orebro splint. Aim The aims were to investigate how many children, despite treatment with the Orebro splint, developed dysplasia in the adolescence period, to study the hip function in children treated with the Orebro splint and investigate if there were any differences in treatment outcomes between males and females. Methods All children born between 2000 and 2012, treated with the Orebro splint, were eligible for inclusion. The outcome measures for quality of life and hip function were EQ-5D-Y-VAS and CHOHES score. The outcome measures for the pelvic radiological exams were Acetabular Index and Center Edge angle. Results Data from 46 patients were collected, 7 males and 39 females. 5,3% of the patients showed residual dysplasia. Both males and females showed overall good results in the radiological images, the surveys, and the clinical exams. The results did not show significant differences between the genders. Conclusion Even though our participants reported an overall good quality of life, our results showed some cases of residual dysplasia. However, the small sample size makes it difficult to assess whether the Orebro splint is equal to other splints regarding treatment outcomes.

Developmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult life. To this day several non-surgical treatments involving the use of harnesses and braces have been proposed to treat DDH in infants, with the Pavlik harness being the current non-surgical standard used to treat DDH at early stages. Although the Pavlik harness has been proven to be successful treating subtle dislocations, severe dislocations do not always reduce. Until now the use of the harness remains an empirical method, and its effectiveness often depends on physician expertise or trial-error procedures; thus a clear guideline has not been established to determine the best optimal harness configuration to treat both subtle and severe dislocations. The goal of this dissertation is to understand the connection between reductions for subtle and severe dislocations and passive muscle forces and moments generated while the harness is used during treatment. While the understanding of DDH biomechanics will provide a valuable clinically applicable approach to optimize and increase harness success rate, it is not without its difficulties. This research has created and developed a three-dimensional based on patient-specific geometry of an infant lower limb. The kinematics and dynamics of the lower limb were defined by modeling the hip, femur, tibia, fibula, ankle, foot, and toe bones. The lines of action of five (5) adductor muscles, namely, the Adductor Brevis, Adductor Longus, Adductor Magnus, Pectineus, and Gracilis were identified as mediators of reduction and its mechanical behavior was characterized using a passive response. Four grades (1-4) of dislocation as specified by the International Hip Dysplasia Institute (IHDI) were considered, and the computer model was computationally manipulated to represent physiological dislocations. To account for proper harness modeling, the femur was restrained to move in an envelope consistent with its constraints. The model of the infant lower limb has been used to analyze subtle and severe dislocations. Results are consistent with previous studies based on a simplified anatomically-consistent synthetic model and clinical reports of very low success of the Pavlik harness for severe dislocations. Furthermore the findings on this work suggest that for severe dislocations, the use of the harness could be optimized to achieve hyperflexion of the lower limb leading to successful reduction for cases where the harness fails. This approach provides three main advantages and innovations: 1) the used of patient-specific geometry to elucidate the biomechanics of DDH; 2) the ability to computationally dislocate the model to represent dislocation severity; and 3) the quantification of external forces needed to accomplish reduction for severe dislocations. This study aims to offer a practical solution to effective treatment that draws from engineering expertise and modeling capabilities and also draws upon medical input. The findings of this work will lay the foundation for future optimization of non-surgical methods critical for the treatment of DDH.

brace on the child's motor development and it briefly informs about the possibilities of the objective evaluation of child' significant influence of the diagnosis DDH and inseparable orthopaedic brace on the child's - ltaneusly intensive physiotherapy using Vojta's reflex