557 research outputs found
Foot Deformity and Bone Strength in Charcot Neuropathic Osteoarthropathy
Charcot neuropathic osteoarthropathy: CN) is characterized by progressive degradation of bones and joints in a denervated, inflamed foot and ankle. Diabetes mellitus: DM) and peripheral neuropathy: PN) are the most common precursors of CN, which can lead to pedal fracture, subluxation, and dislocation. Bone injury and subtle articular damage characteristic of incipient CN are difficult to visualize with planar radiographs. As a result, CN often progresses until more serious, clinically obvious events occur, contributing to increased risk of ulceration, infection, amputation, and death.
The overall purpose of this research was to develop methods using volumetric quantitative computed tomography: vQCT) to assess foot bone strength and foot deformity, in order to provide improved indices of CN onset and progression. Aim 1 describes the development of methods to assess bone mineral density: BMD) and geometric bone strength indices in human metatarsals, as well as an ex vivo validation of ultimate loading strength using cadaver samples. Results in Aim 1 showed that BMD and indices of compressive, bending, and buckling strength were strong correlates of metatarsal ultimate strength. Aim 2 provides group comparisons of vQCT-derived bone strength indices between CN and non-CN individuals, with results showing large decrements in BMD in individuals with CN, though no group differences were found for geometric strength indices. Aim 3 presents method development and reliability assessment of novel 3D techniques to assess foot deformities using bone surface atlases of the tarsal and metatarsal bones, with results suggesting that an automated, template-based method can provide equivalent measurement precision to expert testers. In Aim 4, vQCT-derived, 3D foot deformity measures were compared between CN and non-CN individuals; results showed significant alterations in bone-to-bone orientations that corroborate sagittal plane measurements from X-rays and also provide novel deformity measures that cannot be made using uni-planar X-rays.
This dissertation research, completed under the direction of an interdisciplinary team of physical therapists, biomedical engineers, radiologists, and orthopedic surgeons, provides new information regarding bone strength and foot deformities in Charcot neuropathic osteoarthropathy. Most importantly, the tools developed in the course of this research have potential utility for future research to understand the pathophysiological pathways linking diabetes, peripheral neuropathy, foot deformities, and the development and progression of Charcot neuropathic osteoarthropathy
Automated measurement of foot deformities : flatfoot, high arch, calcaneal fracture
Radiographic measurements of foot deformities are used to determine, among other things, such conditions as flatfoot, high arch, or calcaneal fracture. Those measurements are achieved by estimating four angles. Manual assessment of those angles is time-consuming not to mention inevitable errors of such approximation. To the best of the authors knowledge, currently there is no research focusing on finding those four angles. In this paper an algorithm for automatic assessment of those angles, based on extremely randomized trees, is being proposed. Moreover this diagnostic assisting system was intended to be as generic as possible and could be applied, to some degree, to other similar problems. To demonstrate usefulness of this method, correlations of automated measurements with manual ones against correlations of manual measurements with manual ones are being compared. The significance level for manual-manual measurements comparison is less than 0.001 in case of all four angles. The significance level for automated-manual measurements comparison is also less than 0.001 in all cases. The results show that the search for the aforementioned angles can be automated. Even with the use of a generic algorithm a high degree of precision can be achieved, allowing for a more efficient diagnosis
A new approach in the clinical decision-making for cerebral palsy using three-dimensional subject-specific musculoskeletal reconstructions.
Cerebral palsy (CP) is a neurological disorder which can cause muscular spasticity. Children with this condition suffer from a combination of gait deviations, skeletal deformities and muscular abnormalities. Precise evaluation of each of these three components is crucial for management planning in children with CP. The aim of this study is to review the latest innovative methods used for three-dimensional (3D) gait analysis and musculoskeletal modeling in children with cerebral palsy. 3D gait analysis is a quantitative objective method based on the use of infrared cameras. It allows the evaluation of dynamic joint angles, forces and moments applied on joints and is usually coupled with dynamic electromyography. Skeletal evaluation is usually based on two-dimensional X-rays and physical examination in clinical practice. However, a novel method based on stereoradiographic 3D reconstruction of biplanar low dose X-rays allows a more thorough evaluation of skeletal deformities, and in particular torsional anomalies. Muscular evaluation of children with CP is most commonly based on magnetic resonance imaging, whereby delimitation of lower limb muscles on axial slices allows 3D reconstruction of these muscles. Novel innovative techniques allow similar reconstructions by extrapolation, thus limiting the necessary quantity of axial slices that need to be manually delimitated.This study has been funded by the Research Council of Saint Joseph University (grant # FM 244) and the CEDRE project (grant N# 11 SCI F 44/L36)
Lower-limb lengths and angles in children older than six years: Reliability and reference values by EOS® stereoradiography
Lower-limb alignment in children is classically assessed clinically or based on conventional radiography, which is associated with projection bias. Low-dose biplanar radiography was described recently as an alternative to conventional imaging. The primary objective of this study was to assess the reliability of length and angle values inferred from 3D reconstructions in children seen in everyday practice. The secondary objective was to obtain reference values for goniometry parameters in children. The paediatric reliability study was done in 18 volunteers who were divided into three groups based on whether they were typically developing (TD) children, had skeletal development abnormalities, or had cerebral palsy. The reference data were obtained in 129 TD children. Each study participant underwent biplanar radiography with 3D reconstruction performed by experts and radiology technicians. Goniometry parameters were computed automatically. Reproducibility was assessed based on the intra-class coefficient (ICC) and the ISO 5725 standard (standard deviation of reproducibility, SDR). For length parameters, the ICCs ranged from 0.94 to 1.00 and the SDR from 2.1 to 3.5 mm. For angle parameters, the ICC and SDR ranges were 0.60–0.95 and 0.9°–4.6°, respectively. No significant differences were found across experts or radiology technicians. Age-specific reference data are reported. These findings confirm the reliability of low-dose biplanar radiography for assessing lower-limb parameters in children seen in clinical practice. In addition, the study provides reference data for commonly measured parameters
Hip deformities and femoroacetabular impingement
RESUMO: Conceptualmente, a conservação de uma estrutura anatómica é mais benéfica do que a sua
substituição. No caso das articulações humanas, este conceito é particularmente importante face
aos mĂşltiplos problemas, ainda nĂŁo resolvidos, relacionados com prĂłteses e materiais usados na
cirurgia ortopédica. Na articulação coxofemoral, o conceito de preservação, melhorando os
parâmetros biomecânicos, assume uma complexidade técnica acrescida maioritariamente pelo
facto de a circulação epifisária do fémur ser intra-articular e dada a proximidade de importantes
estruturas neurovasculares.
O conflito femoroacetabular (CFA) e a displasia acetabular no adulto jovem, sĂŁo duas entidades
patológicas comuns embora com múltiplas áreas ainda por investigar. A displasia infantil, não
diagnosticada e não tratada, pode originar displasia acetabular residual na idade adulta e consequente sintomatologia e limitação funcional. O diagnóstico de CFA no adulto é baseado em
critĂ©rios clĂnicos e radiográficos. Clinicamente apresenta-se igualmente com dor e limitação
funcional. Radiologicamente, dois subtipos de CFA sĂŁo habitualmente reconhecidos, o tipo
Cam (mecanismo patológico decorrente de asfericidade femoral) e o tipo Pincer (por hipercobertura acetabular). Embora com padrões diferentes de envolvimento articular, os dois mecanismos de conflito condicionam dor, lesão estrutural do labrum e condropatia.
Atualmente, a morfologia Cam Ă© considerada como um dos principais fatores de risco morfolĂłgico que contribuem para o desenvolvimento de osteoartrose precoce da coxofemoral, eventualmente com necessidade de recurso a prĂłtese total da anca.
Apesar de a investigação inicial na área da cirurgia conservadora da anca ter documentado bons
resultados cirúrgicos, atualmente a controvérsia é francamente superior ao consenso relativamente à melhor abordagem diagnóstica e terapêutica.
Caracteristicamente, apesar de em muitos casos os achados clĂnicos e radiolĂłgicos serem inequĂvocos para o diagnĂłstico de CFA, um nĂşmero substancial de doentes apresenta achados frustes
ou equĂvocos. Por outro lado, mĂşltiplos estudos descreveram uma alta prevalĂŞncia de morfologia
compatĂvel com CFA na população adulta e em indivĂduos saudáveis assintomáticos. Atualmente,
nĂŁo existe uma ferramenta de imagem ideal que facilite a alocação fidedigna de todos os doentes a um grupo patolĂłgico especĂfico ou, por outro lado, exclua com confiança o diagnĂłstico de
conflito. No entanto, os parâmetros de imagem podem ser utilizados para analisar e descrever as
diferentes caracterĂsticas morfolĂłgicas da anca e adicionalmente confirmar o diagnĂłstico de CFA.
Esta tese enfoca, por um lado, a avaliação da morfologia coxofemoral em diferentes populações, investigando quais articulações estão mais predispostas ao desenvolvimento de sintomas e,
por outro, os resultados do tratamento cirĂşrgico de uma coorte com o diagnĂłstico de CFA tipo
Cam. Especificamente, a investigação efetuada: 1) examinou caracterĂsticas morfolĂłgicas especĂficas da coxofemoral em diferentes populações (sintomáticas ou nĂŁo sintomáticas); 2) desenhou
um modelo estatĂstico baseado em preditores anatĂłmicos no sentido de estabelecer as articulações em risco de desenvolvimento sintomático, incorporando geometrias articulares especĂficas
e parâmetros espinhopélvicos; e 3) analisou os resultados de terapêutica cirúrgica numa coorte
de doentes com o diagnĂłstico CFA tipo Cam.
Durante a progressĂŁo clĂnica na área da imagiologia e nesta área patolĂłgica em particular,
apercebemo-nos da existência de múltiplas lacunas de conhecimento que procurámos colmatar
com a investigação agora publicada e descrita nesta tese. A sistematização por capĂtulos reflete
precisamente a necessidade de abordar a questão em áreas de conhecimento, simultaneamente
distintas e complementares.
Os seis capĂtulos desta tese abrangem o espectro clĂnico desde o diagnĂłstico atĂ© ao tratamento
da anca jovem. De modo a apresentar os objetivos desta tese numa sequĂŞncia lĂłgica, desde a
anatomia geral atĂ© Ă morfologia e tratamento especĂficos do CFA, a análise da anca assintomática
será descrita em primeiro lugar seguida pela análise da relação anatomoclĂnica entre morfologia
articular e sintomas. Por último será abordada a terapêutica do doente sintomático.
Na PARTE I, apresentamos os tópicos essenciais para compreender a abrangência do espectro da presente tese, designadamente a relevância e a contemporaneidade do tema “CFA”
e adicionalmente o enquadramento anatómico, morfológico e vascular desta articulação.
O CapĂtulo 1 Ă© dedicado ao desenvolvimento e morfogĂ©nese da anca. No CapĂtulo 2,
sublinhamos a importância e o papel da imagem atravĂ©s de uma revisĂŁo enfocada nas perspetivas atuais e futuras sobre este tĂłpico (Artigo I). No CapĂtulo 3, realizamos uma revisĂŁo
sistemática da literatura no sentido de descrever o estado da arte com foco na prevalência
da morfologia de CFA em populações assintomáticas e sintomáticas. Este capĂtulo destaca as
múltiplas lacunas de conhecimento relativas ao papel da morfologia da articulação coxofemoral na patogénese do CFA (Artigo II).
Com base nesta parte introdutĂłria, abordamos seguidamente os objetivos da presente tese,
gerais e especĂficos, na PARTE II.Na PARTE III, descrevemos o corpo da investigação clĂnica original efetuada. O CapĂtulo 4
é dedicado à caracterização detalhada da morfologia da anca, designadamente óssea e vascular. A morfologia coxofemoral foi quantificada utilizando software com capacidade de
semi-automatização analĂtica, permitindo estudar a prevalĂŞncia e relação entre as diferentes
morfologias articulares e o género, dominância e simetria articular (Artigo III). A morfologia
Cam foi ainda alvo de caracterização mais aprofundada, através do desenvolvimento de um
novo parâmetro quantitativo com potencialidade diagnóstica e de planeamento cirúrgico/
/prognóstico, primariamente testado numa coorte assintomática (Artigo IV) e seguidamente
também em doentes com indicação cirúrgica (Artigo V).
Na nossa atividade clĂnica diária apreciámos a necessidade urgente de melhor caracterizar a
topografia da deformidade Cam e a respetiva relação com as artĂ©rias nutritivas da epĂfise femoral.
A impressĂŁo clĂnica referida sugeria que a morfologia Cam frequentemente se estendia posteriormente ao quadrante pĂłstero-superior, intersectando a regiĂŁo retinacular vascular. No entanto,
por imagem a natureza arterial destas estruturas nunca havia sido confirmada. Por esta razĂŁo,
a importância do parâmetro mencionado foi sublinhada e comprovada no estudo cadavérico
com avaliação topográfica vascular do fémur proximal (Artigo VI).
No CapĂtulo 5 testámos mĂşltiplos parâmetros imagiolĂłgicos e respetivas variações/relações
com diferentes morfologias coxofemorais, no sentido de identificar as articulações com risco
clĂnico aumentado de desenvolvimento sintomático. Para este fim efetuámos estudos baseados
em computação avançada com modelação estatĂstica (Artigo VII) e tambĂ©m em ressonância
magnética (RM) tridimensional (Artigo VIII).
O CapĂtulo 6 descreve as opções de tratamento (Artigo IX) e os resultados clĂnicos num estudo
clĂnico de uma coorte com follow-up mĂnimo de 2 anos, comparando a abordagem cirĂşrgica
aberta e artroscĂłpica (Artigo X).
Os resultados dos diferentes capĂtulos estĂŁo sumarizados na PARTE IV, onde apresentamos a sĂntese geral, a discussĂŁo crĂtica dos resultados obtidos Ă luz da literatura atual e finalmente as conclusões relevantes. As oportunidades futuras de investigação sĂŁo igualmente abordadas neste capĂtulo.
Em resumo o trabalho constante da presente tese sugere:
Primeiro, que a avaliação imagiológica detalhada da morfologia coxofemoral é essencial
no sentido de compreender aprofundadamente não só a própria articulação como também
a morfologia pélvica (Artigo I).
Segundo, paradoxalmente, a definição clĂnica de um caso patolĂłgico e das diferentes
entidades relacionadas, é ainda inexistente. Os parâmetros quantitativos e qualitativos que
comummente estĂŁo associados com CFA tipo Pincer e Cam sĂŁo francamente frequentes
em diferentes populações (sintomáticas e assintomáticas) (Artigo II).Terceiro, em populações assintomáticas adultas, os intervalos de referĂŞncia especĂficos
para os parâmetros quantitativos associados a morfologia de CFA e displasia são mais latos
e com limites superiores mais elevados do que os atualmente utilizados na prática clĂnica (Artigo III). A morfologia femoral bem como os epicentros/magnitudes das deformidades Cam sĂŁo especĂficos de gĂ©nero, observando-se maiores valores de ângulo alfa
e Ăłmega em indivĂduos do sexo masculino (Artigo IV).
Quarto, é frequente a interseção entre a extensão póstero-superior da deformidade Cam
e a convergência epifisária das estruturas vasculares retinaculares observadas em RM, aspetos que se revestem de primordial importância no planeamento cirúrgico. Adicionalmente
a extensĂŁo radial da deformidade Cam (ângulo Ăłmega) está significativamente mais relacionada com a sintomatologia clĂnica prĂ©-cirĂşrgica do que o parâmetro mais comummente
utilizado na prática clĂnica (ângulo alfa) (Artigo V). A origem das estruturas vasculares
observadas por RM na prega retinacular Ă© inequivocamente arterial, sendo que abrange
uma extensĂŁo mais anterior do que classicamente assumido (Artigo VI).
Quinto, as geometrias ovalares (em detrimento das morfologias esféricas e elipsoides)
sĂŁo melhor representativas de ambas as superfĂcies articulares da coxofemoral, designadamente do fĂ©mur e acetábulo, bem como das ancas sintomáticas que clinicamente exibem
sinais de CFA (Pincer, Cam e misto) (Artigo VII). IndivĂduos com maiores deformidades Cam, aspetos de hipocobertura acetabular e acentuação da anteflexĂŁo pĂ©lvica apresentam uma maior probabilidade de desenvolverem sintomas articulares (Artigo VIII).
Esta observação Ă© crĂtica, dado que fornece, na prática clĂnica, informação essencial acerca
da potencial predisposição para fenómenos de exacerbação sintomática futura, permitindo
desta forma instituição de medidas terapêuticas/preventivas adequadas. Na perspetiva do
doente, um diagnóstico precoce e preciso, pode conceptualmente prevenir, numa primeira fase, alterações condropáticas articulares e, numa segunda instância, progressão para
artrose estabelecida.
Sexto, documentamos resultados clĂnicos e funcionais significativamente favoráveis quando
comparamos a abordagem artroscĂłpica e aberta no tratamento cirĂşrgico da deformidade
Cam, sendo de observar que o género feminino está associado a menor score funcional na
avaliação pré-operatória (Artigos IX e X).
Futuramente, a imagiologia e a cirurgia conservadora da anca irĂŁo desenvolver-se conjuntamente e em paralelo com novos e maiores desafios. A descrição de novos parâmetros analĂticos
para avaliação da patoanatomia coxofemoral, associada Ă inovação tecnolĂłgica crescente e Ă
implementação da inteligĂŞncia artificial, impõem uma evolução clĂnica oposta Ă assunção de
classificações patológicas demasiadamente simplistas. Nesse sentido a existência de guidelines de diagnóstico e terapêutica mais efetivas e baseadas na evidência, que nos levem além da pura diferenciação entre CFA e displasia, são urgentes. A história natural das deformidades Cam e Pincer,
sintomáticas ou assintomáticas, é ainda grandemente desconhecida, assumindo-se como uma
área determinante de investigação no que concerne ao diagnóstico, terapêutica e prognóstico.ABSTRACT: Conceptually, the preservation of a human anatomical structure makes more sense than its
replacement. This concept is even more striking in the case of human joints due to the multitude of unsolved problems related to implants used in orthopaedic surgery. With respect to
the hip, joint preservation assumes an increased technical complexity when compared to other
joints; this is due to two main reasons: the intra-articular epiphyseal circulation of the femur and
the proximity of large neurovascular structures.
Femoroacetabular impingement (FAI) and acetabular dysplasia (DHD) in young adults are two
common but poorly characterised pathological entities. If undiagnosed and untreated, dysplasia in
childhood may lead to residual DHD in young adults, as diagnosed on radiographs, and may also
give rise to symptoms such as hip pain and restricted range of motion. The diagnosis of FAI in
adults is based on clinical and imaging criteria. The most frequently noticed symptoms of FAI
include hip pain and restricted function. Radiologically, two main subtypes of FAI are recognised:
The Cam-type, with the pathoanatomical mechanism located on the femoral side, and the Pincertype on the acetabular side. Although with different pathological patterns, both types cause pain
and articular damage of the labrum and cartilage. While Cam-type FAI is believed to be a major
contributing factor to the early onset of hip osteoarthritis (OA), which eventually requires a total
hip replacement, the relationship of other shapes and morphologies with OA are still under debate.
Despite the initial promising reports on outcomes following surgical management of these conditions, the best approach to diagnose and manage them still remains controversial. Although
for some patients there are unambiguous clinical and imaging findings of FAI, for a substantial
number of patients there are minimal or intermediate findings. Moreover, several studies have
reported a high prevalence of FAI morphology among the “normal” population and in asymptomatic healthy individuals. At present, there is no adequate imaging tool to facilitate the reliable
allocation of all patients into the correct diagnostic group or to confidently rule out diagnosis.
However, imaging parameters can be used to describe different hip morphological characteristics and additionally confirm or preclude the diagnosis of FAI.This thesis focuses on assessing hip morphology in different populations by investigating which
specific joints are more prone to developing symptoms and by evaluating treatment outcomes
of a FAI cohort. Specifically, this research concentrates on the following: 1) examining population-specific (symptomatic and non-symptomatic) characteristics of hip morphology; 2) developing an anatomic-based model to establish “at-risk” hip joints, incorporating subject-specific hip
geometries and spinopelvic parameters and 3) investigating treatment outcomes in a Cam-type
FAI cohort.
In our clinical progression in imaging and in this particular area of pathology, we became aware
of the existence of several gaps that we sought to fill with the now published research hereby
described. The systematisation by chapters precisely reflects the need to address the issue in
simultaneously distinct and complementary areas of knowledge.
This thesis consists of six chapters, which cover the entire spectrum from the diagnosis to treatment of the young hip. To present the aims of this thesis in a sequential manner from general
morphology to more specific FAI-related topics, the analysis of the asymptomatic hip will be
presented first, followed by how joint morphology is associated with symptoms and, finally,
will conclude with treatment.
In PART I, we introduce the topics that are relevant to understand the full scope of our thesis;
we aim to accomplish this by addressing the relevance and contemporariness of the “FAI” theme
and by describing the general and vascular anatomy of the hip. Chapter 1 is devoted to hip
development and morphogenesis. In Chapter 2, we address the importance of imaging by conducting a thorough review of current and future perspectives on this topic (Paper I). In Chapter 3,
we perform a systematic review of the literature to write a state-of-the-art overview, focussing
on asymptomatic and symptomatic FAI morphology prevalence and highlighting the multiple
gaps in knowledge regarding the role of hip morphology in the pathogenesis of FAI (Paper II).
Building on the first part, we address the rationale and aims of this thesis in PART II.
In PART III, we describe the original research that was performed and published. Chapter 4
focusses on the detailed characterisation of hip morphology, both osseous and vascular. Bony
hip morphology was quantified using a semi-automated software, which allows to robustly study
in detail shape variants in an asymptomatic population and their relationship with sex, side and
limb dominance (Paper III). Cam morphology was further defined by developing a novel quantitative parameter, with diagnostic and treatment planning capabilities using a cohort of both
asymptomatic individuals (Paper IV) and patients undergoing surgery (Paper V). Moreover, we
felt the need to better characterise the topography of the deformity and its relationship with
the nourishing arteries of the femoral head, as Cam morphology frequently has a posterior
a bstr extension that overlaps the retinacular vascular structures. However, its arterial origin has never
been described or confirmed in the literature. For this reason, the importance of the aforementioned parameter has been outlined by the cadaveric arterial topographic study of the proximal
femur (Paper VI). In Chapter 5, we test multiple parameters and their associated shape variants
to detect which ones allow identifying a risk-increased joint in various populations. To this end,
we use both advanced computing for shape modelling (Paper VII) and three dimensional (3D)
magnetic resonance imaging (MRI) (Paper VIII). Chapter 6 describes the various treatment
options (Paper IX) and outcomes in a cohort clinical study, comparing open surgery with
arthroscopic surgery in terms of treating Cam deformities (Paper X).
The results of the aforementioned chapters are summarised in PART IV, presenting the general
synthesis, discussing the results in the light of current literature and detailing the conclusions of
this thesis. The scope of potential future research within this field is also presented in this chapter.
In brief, this thesis suggests the following:
First, detailed imaging assessment of hip morphology is paramount to better understanding both the hip joint and pelvic morphology (Paper I).
Second, the case definitions of different morphologies and clinical entities are missing as
far as FAI and related disorders are concerned. Qualitative and quantitative radiographic
findings thought to be associated with Cam- and Pincer-type FAI, as well as the coexistence between them, are quite common among different populations (Paper II).
Third, in adult asymptomatic populations, sex-specific reference intervals for hip measurements for DHD and FAI morphology are wider than currently accepted values (Paper III).
Moreover, femoral morphology with distinct Cam magnitudes and epicentres is also
sex-specific, with higher mean alpha angle (α°) and omega angle (Ω°) values seen in males
(Paper IV).
Forth, Cam deformity frequently overlaps with the retinacular vascular structures seen
in an MRI; this finding has practical surgical relevance. Additionally, the radial extension
of the Cam deformity (Ω°) is more significantly associated with the patients’ symptoms
prior to surgery than the α° (paper V). The origin of the vascular structures seen in the
retinacular fold is unequivocally arterial in nature, and these structures have a more anterior
distribution than classically assumed (Paper VI).
Fifth, ovoid geometries are more representative of both articular surfaces of the hip joint as
well as of Cam, Pincer and mixed impinged hips when compared to spherical or ellipsoidal shapes (Paper VII). Individuals with larger Cam deformities, decreased acetabular coverage
and increased pelvic anteflexion are more likely to experience hip symptoms (Paper VIII).
This provides clinicians with indications of how the pathology exacerbates, allowing them
to perform the correct clinical assessments and proceed with the correct form of care.
From a patient’s perspective, an early and accurate diagnosis could prevent cartilage degradation and progression to OA.
Sixth, similar outcomes and significant functional improvement are observed when comparing open and arthroscopic surgery in the treatment of Cam deformities (follow-up
time of two years). It should be noted that the female gender was associated with poor hip
function in the preoperative evaluation (papers IX and X).
Looking ahead, imaging and hip preserving surgery (HPS) will evolve hand-in-hand in the
face of new and greater challenges. The increasing number of analytic parameters describing
hip joint pathomorphologies as well as new sophisticated 3D imaging-analysis together with
emerging artificial intelligence-based technologies have transported us beyond simple classification systems. Moreover, more reliable diagnostic and treatment guidelines that go beyond
differentiation into pure FAI and dysplasia are paramount. The largely unknown natural course
of both hips with symptomatic FAI and asymptomatic individuals continues to present research
opportunities as far as diagnosis, treatment and prognosis are concerned
Three-dimensional computation of femoral canine morphological parameters: from the theory to the surgery application
The present research was envisioned as a project defined by multiple studies that are strictly correlated each other. The report of the birth, development and practical application to the diagnostic and surgery fields of a novel 3D approach for the computation of femoral measurements was the first aim. Moreover, in the authors’ purpose the description of the translational value of the proposed procedure enhanced with its plausible utility to the daily practice of orthopaedic surgeons, represented another focal point.
In this sense, the research started from the validation of the 3D assessment of femoral morphometric parameters. Veterinary literature reports tons of papers describing several methodologies for obtaining femoral measurements through different diagnostic techniques. Furthermore, bibliography presents lot of angles values that are currently adopted and considered as reference parameters for most of the corrective osteotomies. Additionally, in the recent past an increased emphasis on 3D approach grown but little if any attention was devoted to 3D measurements. This trend represented in the authors’ mind the gap with the current knowledge and, thus, an area to be deeply investigated. Indeed, to the best of author knowledge, there were no papers documenting the assessment of 3D femoral axes and angles in veterinary medicine, with no 3D protocol described. In addition, currently available canine femoral measurements related to frontal, sagittal and transverse deformities have only been computed in bi-planar projections, whether acquired from 2D or 3D imaging models.
Therefore, starting from the accepted human methods and from the features definition in veterinary literature, we proposed a new approach.
The first study was designed to define a 3D methodology, introducing a consistent and quantitative method for the assessment of femoral morphometric parameters in 3D geometrical models. To validate the proposed approach, accurate geometric data were necessary and, therefore, we opted for meshes obtained by a 3D scanner, instead of CT images. Once the validation of the was stated, our focus was directed towards the evaluation of the precision of the proposed 3D protocol.
The validation of a novel diagnostic test requires verification of the repeatability, defined as the strength of agreement between repeated measurements of the same samples performed from one examiner, and the reproducibility as well, that express the same variance but between a group of observers.
Furthermore, the accuracy of the measurements indicates how close the measurements took with the investigated technique to a true value (gold standard). Therefore, a second project was designed to test the precision of three diagnostic techniques, two largely diffuse (Rx and TC) one recently introduced in veterinary (3D), for the measurement of femoral angles.
The second purpose of this study was the investigation of the potential application of the algorithm implemented in a computer-aided-design (CAD) software, using CT data. Considering that for the first study we worked with 3D scanner data, the main aim at this point of the research was represented by the enhancement of the presented 3D protocol for diagnostic purposes. In the author opinion, changing the source of data was necessary because of the availability of CT and MRI equipment in veterinary practice.
Finally, the last goal of this project was the translation of the application of 3D computation to the surgical field. The current research contemplates the fact that the augmented interest on 3D computation is not only relevant for diagnostic reasons, but also for surgery. Thus, the correlation between the diagnostic utility of the 3D approach and its plausible practice for surgery purposes was the object of the final study. The starting point was suggested by veterinary literature that reports in few papers the development and application of surgical devices used to perform assisted-correction of bone deformities.
These surgical tools are designed through 3D geometrical models and act both as precise intraoperative localizers of osteotomy corrective landmarks and surgical saw guides.
Three-dimensional assessment of a bone conformation may improve the understanding and evaluation of bone deformities and occurring joints malalignment. In this sense, the localization of the CORA as well as the accuracy of the orientation of the osteotomy-cutting plane may be significantly upgraded through a 3D approach
Assessing 3D paediatric foot morphology using low-dose biplanar radiography: Parameter reproducibility and preliminary values
The physical examination and weight-bearing radiography are the two main available methods for assessing the feet and lower limbs. The anatomy and function of these two structures interact with each other. These two assessment methods are affected by subjectivity and projection bias. Low-dose biplanar radiography (LDBR) is now a promising alternative for evaluating the lower limbs in children. At present, however, the foot cannot be assessed using LDBR. The objective of this study was to work towards developing a new method for 3D radiographic analysis of the paediatric foot during weight-bearing, first by determining the reproducibility of landmarks defined by LDBR then by reporting the values of the calculated radiographic parameters. Two biplanar radiographs in perpendicular planes were obtained simultaneously in a standardised position using the EOS system (EOS® Imaging, Paris, France) in each of 10 healthy children. To assess measurement uncertainty, two observers performed 3D reconstructions of each of the 10 feet three times (60 reconstructions). The standard error of reproducibility of the anatomic landmarks and clinical parameters was computed. Measurement uncertainty was then estimated based on the 95% confidence interval (95%CI). To obtain reference values, the mean ± SD of each variable was computed after checking that the data were normally distributed. Reproducibility was high for the anatomical landmarks of interest, calcaneal pitch angle, tibio-calcaneal angle on the lateral view, and first metatarsal pitch angle (95%CI < 5%). The values of these angles in the study population are reported. The data reported here pave the way towards developing new parameters for describing 3D foot morphology and for simultaneously assessing the lower limb and foot in the standing position.The authors are also grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling
Identifying the Severity of Adolescent Idiopathic Scoliosis During Gait by Using Machine Learning
La scoliose idiopathique de l'adolescent (SIA) est une déformation de la colonne vertébrale dans les trois plans de l’espace objectivée par un angle de Cobb ≥ 10°. Celle-ci affecte les adolescents âgés entre 10 et 16 ans. L’étiologie de la scoliose demeure à ce jour inconnue malgré des recherches approfondies. Différentes hypothèses telles que l’implication de facteurs génétiques, hormonaux, biomécaniques, neuromusculaires ou encore des anomalies de croissance ont été avancées. Chez ces adolescents, l'ampleur de la déformation de la colonne vertébrale est objectivée par mesure manuelle de l’angle de Cobb sur radiographies antéropostérieures. Cependant, l’imprécision inter / intra observateur de cette mesure, ainsi que de l’exposition fréquente (biannuelle) aux rayons X que celle-ci nécessite pour un suivi adéquat, sont un domaine qui préoccupe la communauté scientifique et clinique. Les solutions proposées à cet effet concernent pour beaucoup l'utilisation de méthodes assistées par ordinateur, telles que des méthodes d'apprentissage machine utilisant des images radiographiques ou des images du dos du corps humain. Ces images sont utilisées pour classer la sévérité de la déformation vertébrale ou pour identifier l'angle de Cobb. Cependant, aucune de ces méthodes ne s’est avérée suffisamment précise pour se substituer l’utilisation des radiographies.
Parallèlement, les recherches ont démontré que la scoliose modifie le schéma de marche des personnes qui en souffrent et par conséquent également les efforts intervertébraux. C’est pourquoi, l'objectif de cette thèse est de développer un modèle non invasif d’identification de la sévérité de la scoliose grâce aux mesures des efforts intervertébraux mesurés durant la marche. Pour atteindre cet objectif, nous avons d'abord comparé les efforts intervertébraux calculés par un modèle dynamique multicorps, en utilisant la dynamique inverse, chez 15 adolescents atteints de SIA avec différents types de courbes et de sévérités et chez 12 adolescents asymptomatiques (à titre comparatif). Par cette comparaison, nous avons pu objectiver que les efforts intervertébraux les plus discriminants pour prédire la déformation vertébrale étaient la force et le couple antéro-postérieur et la force médio-latérale. Par la suite, nous nous sommes concentrés sur la classification de la sévérité de la déformation vertébrale de 30 AIS ayant une courbure thoraco-lombaire / lombaire. Pour ce faire, nous avons testé différents modèles de classification. L'angle de Cobb a été identifié en exécutant différents modèles de régression. Les caractéristiques (features) servant à alimenter les algorithmes d'entraînement ont été choisies en fonction des efforts intervertébraux les plus pertinents à la déformation vertébrale au niveau de la charnière lombo-sacrée (vertèbres allantes de L5-S1). Les précisions les plus élevées pour la classification exécutant différents algorithmes ont été obtenues par un algorithme de classification d'ensemble comprenant les “K-nearest neighbors”, “Support vector machine”, “Random forest”, “multilayer perceptron”, et un modèle de “neural networks” avec une précision de 91.4% et 93.6%, respectivement. De même, le modèle de régression par “Decision tree” parmi les autres modèles a obtenu le meilleur résultat avec une erreur absolue moyenne égale à 4.6° de moyenne de validation croisée de 10 fois.
En conclusion, nous pouvons dire que cette étude démontre une relation entre la déformation de la colonne vertébrale et les efforts intervertébraux mesurés lors de la marche. L'angle de Cobb a été identifié à l'aide d'une méthode sans rayonnement avec une précision prometteuse égale à 4.6°. Il s’agit d’une amélioration majeure par rapport aux méthodes précédemment proposées ainsi que par rapport à la mesure classique réalisée par des spécialistes présentant une erreur entre 5° et 10° (ceci en raison de la variation intra/inter observateur). L’algorithme que nous vous présentons peut être utilisé comme un outil d'évaluation pour suivre la progression de la scoliose. Il peut être considéré comme une alternative à la radiographie. Des travaux futurs devraient tester l'algorithme et l’adapter pour d’autres formes de SIA, telles que les scolioses lombaire ou thoracolombaire.----------ABSTRACT
Adolescent idiopathic scoliosis (AIS) is a 3D deformation of the spine and rib cage greater than 10° that affects adolescents between the ages of 10 and 16 years old. The true etiology is unknown despite extensive research and investigation. However, different theories such as genetic and hormonal factors, growth abnormalities or biomechanical and neuromuscular reasons have been proposed as possible causes. The magnitude of spinal deformity in AIS is measured by the Cobb angle in degrees as the gold standard through the X-rays by specialists. The inter/intra observer error and the cumulative exposure to radiation, however, are sources of increasing concern among researchers with regards to the accuracy of manual measurement. Proposed solutions have therefore, focused on using computer-assisted methods such as Machine Learning using X-ray images, and/or trunk images to classify the severity of spinal deformity or to identify the Cobb angle. However, none of the proposed methods have shown the level of accuracy required for use as an alternative to X-rays. Meanwhile, scoliosis has been recognized as a pathology that modifies the gait pattern, subsequently impinging upon intervertebral efforts. The present thesis aims to develop a radiation-free model to identify the severity of idiopathic scoliosis in adolescents based on the intervertebral efforts during gait.
To accomplish this objective, we compared the intervertebral efforts computed using a multibody dynamics model, by way of inverse dynamics, among 15 adolescents with AIS having different curve types and severities, as well as 12 typically developed adolescents. This resulted in the identification of the most relevant intervertebral efforts influenced by spinal deformity: mediolateral (ML) force; anteroposterior (AP) force; and torque. Additionally, we focused on the classification of the severity of spinal deformity among 30 AIS with thoracolumbar/lumbar curvature, testing different classification models. Lastly, the Cobb angle was identified running regression models. The features to feed training algorithms were chosen based on the most relevant intervertebral efforts to the spinal deformity on the lumbosacral (L5-S1) joint. The highest accuracies for the classification were obtained by the ensemble classifier algorithm, including “K-nearest neighbors”, “support vector machine”, “random forest”, and “multilayer perceptron”, as well as a neural network model with an accuracy of 91.4% and 93.6%, respectively. Likewise, the “decision tree regression” model achieved the best result with a mean absolute error equal to 4.6 degrees of an averaged 10-fold cross-validation. This study shows a relation between spinal deformity and the produced intervertebral efforts during gait. The Cobb angle was identified using a radiation-free method with a promising accuracy, providing a mean absolute error of 4.6°. Compared to measurement variations, ranging between 5° and 10° in the manual Cobb angle measurements by specialists, the proposed model provided reliable accuracy. This algorithm can be used as an assessment tool, alternative to the X-ray radiography, to follow up the progression of scoliosis. As future work, the algorithm should be tested and modified on AIS with other types of spine curvature than lumbar/thoracolumbar
Reconstruction 3D personnalisée de la colonne vertébrale à partir d'images radiographiques non-calibrées
Les systèmes de reconstruction stéréo-radiographique 3D -- La colonne vertébrale -- La scoliose idiopathique adolescente -- Évolution des systèmes de reconstruction 3D -- Filtres de rehaussement d'images -- Techniques de segmentation -- Les méthodes de calibrage -- Les méthodes de reconstruction 3D -- Problématique, hypothèses, objectifs et méthode générale -- Three-dimensional reconstruction of the scoliotic spine and pelvis from uncalibrated biplanar X-ray images -- A versatile 3D reconstruction system of the spine and pelvis for clinical assessment of spinal deformities -- Simulation experiments -- Clinical validation -- A three-dimensional retrospective analysis of the evolution of spinal instrumentation for the correction of adolescent idiopathic scoliosis -- Auto-calibrage d'un système à rayons-X à partir de primitives de haut niveau -- Segmentation de la colonne vertébrale -- Approche hiérarchique d'auto-calibrage d'un système d'acquisition à rayons-X -- Personalized 3D reconstruction of the scoliotic spine from hybrid statistical and X-ray image-based models -- Validation protocol
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