Growth Plate Injuries of the Lower Extremity: Case Examples and Lessons Learned.

BackgroundThe presence of growth plates at the ends of long bones makes fracture management in children unique in terms of the potential risk of developing angular deformities and growth arrest.Materials and methodsWe discuss three distinct cases depicting various aspects of physeal injury of the lower extremity in children.ResultsThe case illustrations chosen represent distinct body regions and different physeal injuries: Salter-Harris II fracture of the distal femur, Salter-Harris VI perichondrial injury of the medial aspect of the knee region, and Salter-Harris III fracture of the distal tibia. The clinical presentation, pertinent history and physical findings, imaging studies, management, and subsequent course are presented.ConclusionsGrowth plate injuries of the lower extremity require a high index of suspicion and close monitoring during skeletal growth. Early recognition and proper management of these injuries can minimize long term morbidity. The treatment plan should be individualized after a comprehensive analysis of the injury pattern in each patient. Establishing a long term treatment plan and discussing the prognosis of these injuries with the child's caretakers is imperative

Restoration of Native Leg Length After Opening-Wedge High Tibial Osteotomy: An Intraindividual Analysis

BACKGROUND Opening-wedge high tibial osteotomy (OWHTO) has been shown to significantly increase leg length, especially in patients with large varus deformity. Thus, the current literature recommends closing-wedge high tibial osteotomy to correct malalignment in these patients to prevent postoperative leg length discrepancy. However, potential preoperative leg length discrepancy has not been considered yet. HYPOTHESIS It was hypothesized that patients have a decreased preoperative length of the involved leg compared with the contralateral side and that OWHTO would subsequently restore native leg length. STUDY DESIGN Case series; Level of evidence, 4. METHODS Included were 67 patients who underwent OWHTO for unilateral medial compartment knee osteoarthritis and who received full leg length assessment pre- and postoperatively. Patients with varus or valgus deformity (>3°) of the contralateral side were excluded. A musculoskeletal radiologist assessed imaging for the mechanical axis, full leg length, and tibial length of the involved and contralateral lower extremity. Statistical analysis determined the pre- and postoperative leg length discrepancy and the influence of the mechanical axis. RESULTS Most patients (62.7%) had a decreased length of the involved leg, with a mean preoperative mechanical axis of 5.0° ± 2.9°. Length discrepancy averaged -2.2 ± 5.8 mm, indicating a shortened involved extremity (P = .003). OWHTO significantly increased the mean lengths of the tibia and lower limb by 3.6 ± 2.9 and 4.4 ± 4.7 mm (P < .001), leading to a postoperative tibial and full leg length discrepancy of 2.8 ± 4.3 mm and 2.2 ± 7.3 mm (P < .001 and P = .017, respectively). Preoperative leg length discrepancy was significantly correlated with the preoperative mechanical axis of the involved limb (r = 0.292; P = .016), and the amount of correction was significantly associated with leg lengthening after OWHTO (r = 0.319; P = .009). Patients with a varus deformity of ≥6.5° (n = 14) had a preoperative length discrepancy of -4.5 ± 1.6 mm (P < .001) that was reduced to 1.8 ± 3.5 mm (P = .08). CONCLUSION Patients undergoing OWHTO have a preoperative leg length discrepancy that is directly associated with the varus deformity of the involved extremity. As OWHTO significantly increases leg length, restoration of native leg length can be achieved particularly in patients with large varus deformity

Computer aided method for 3D assessment of the lower limb alignment for orthopedic surgery planning

Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Engenharia Clínica e Instrumentação Médica) Universidade de Lisboa, Faculdade de Ciências, 2017Os membros inferiores são responsáveis por fornecer suporte à totalidade do corpo humano e são essenciais nas mais variadas tarefas como estar de pé, andar e correr. Por vezes, e devido a diversos motivos, podem existir defeitos ou deformações nos membros inferiores que têm um impacto direto na qualidade de vida de uma pessoa, quer por se ver afetado o lado estético pessoal ou por condicionar significativamente a mobilidade. Uma característica da estrutura do membro inferior que é diretamente afetada por estas deformações é o seu alinhamento, isto é, a posição relativa dos ossos e articulações que compõem o membro. Graças à evolução da medicina moderna, corrigir estas deformações é agora uma prática bastante comum no campo da cirurgia ortopédica. No entanto, antes de qualquer cirurgia corretiva e até de qualquer planeamento que esta exija, a deformação tem de ser corretamente analisada, o que é feito através da chamada avaliação do alinhamento do membro inferior. Atualmente, num contexto clínico, esta avaliação é feita manualmente num espaço de trabalho bi-dimensional, normalmente utilizando apenas imagens de raios-X da perna inteira no plano anatómico frontal. Uma revisão ao estado da arte no que toca a métodos de planeamento cirúrgico dedicados ao membro inferior permite concluir que de facto existe software capaz de realizar este planeamento, mas que, no entanto, para além de terem custos elevadíssimos associados, nenhum utilizada modelos 3D como fonte de informação, o que traria imensos benefícios, especialmente ao nível da informação acerca da rotação e da inclinação dos ossos. Existem no entanto algum software a um nível mais experimental que utiliza modelos 3D para realizar a avaliação do alinhamento do membro inferior, sendo que nenhum deles passou ainda a estar disponível comercialmente. Numa perspetiva de implementar um método automático baseado em computador para realizar o planeamento pré-cirurgico da cirurgia de correção para ser utilizado em contexto clínico, foi proposto um projeto para o desenvolvimento de um novo software capaz de efetuar a avaliação do alinhamento do membro inferior em modelos 3D dos doentes. O projeto foi dividido em quatro etapas distintas que se desenrolaram ao longo de um estágio de sete meses. Na primeira etapa, o objetivo consistiu em gerar diversos modelos 3D dos membros inferiores de diferentes pacientes. Para tal, recorreu-se ao software de segmentação de imagens médicas Mimics 14.0 e utilizaram-se imagens de tomografia computorizada dos pacientes. Após o processo de segmentação, obtiveram-se os modelos 3D cuja qualidade teve de ser assegurada através de um processo de remeshing e cuja correta orientação espacial teve de ser também assegurada, já que a avaliação do alinhamento é sensível à orientação da perna. Para tal, utilizou-se o software de renderização 3D Geomagic Studio 14. Optou-se ainda por separar os modelos dos ossos nas suas porções proximal e distal, de modo a reduzir futuramente os tempos de computação. Findo todo este processo, assegurou-se que diferentes utilizadores poderiam gerar estes modelos sem grande variabilidade ou erro no resultado final através da comparação dos modelos obtidos de um mesmo paciente por três utilizadores distintos, sendo que os modelos obtidos apresentavam volumes com diferenças inferiores a 1% relativamente ao valor médio e com um baixo desvio padrão. Numa segunda etapa, os ângulos e medidas consideradas necessárias para uma avaliação adequada foram definidos, apresentando os valores esperados para estas medidas de acordo com a literatura. Assim, foi possível definir também os pontos anatómicos que são necessários para a definição destes mesmos ângulos e medidas e que portanto têm de ser encontrados pelo software. Na terceira etapa, fez-se então o desenvolvimento propriamente dito do software. Encontravam-se já disponíveis alguns métodos automáticos desenvolvidos no contexto projeto, contudo, estes métodos exigiam que o utilizador conhecesse as ferramentas do Geomagic de modo a obter algumas informações, e que depois fosse capaz de utilizar estas informações para editar os scripts de modo a que estes funcionassem para cada paciente em específico. Para além disso, apenas pontos muito específicos podiam ser encontrados. Nesse sentido, isto é, de modo a que todo o processo de encontrar os pontos anatómicos relevantes pudesse ser feito diretamente pelo utilizador, no programa, e sem exigir quaisquer conhecimentos de programação, um conjunto de técnicas foi implementado, dando ao programa uma grande componente gráfica. Para os diferentes pontos, foi necessário recorrer a diferentes metodologias, algumas desenvolvidas propositadamente para o efeito e implementadas em linguagem de programação Python "pura", e algumas adaptadas de outras já existentes e disponíveis no próprio Geomagic. Foi ainda assegurado que existiam métodos alternativos caso os métodos padrão não fossem os mais adequados devido a uma estrutura diferente da esperada dos próprios modelos 3D. De todo este processo resultou um programa que usa os modelos 3D gerados e, da maneira mais automática possível e com uma interface do utilizador fácil de usar, fornece todos os ângulos e medidas, efetuando assim a dita avaliação do alinhamento do membro inferior em 3D. Uma análise ponderada aos resultados obtidos permitiu identificar quais os pontos anatómicos que estarão a ser obtidos de maneira menos ideal e por isso a levar a alguns resultados não tão bons como o esperado. A dependência criada da seleção e limitação de certas áreas nas quais ocorre uma iteração que permite encontrar certos pontos é possivelmente a maior falha do programa desenvolvido que se torna assim demasiado sensível ao input do utilizador. Note-se, contudo, que os próprios testes apresentam algumas falhas que podem influenciar os resultados obtidos, tal como não ter sido definido um roteiro de teste que obrigasse a uma utilização uniforme por parte de todos os utilizadores, e também os diferentes níveis de experiência com o programa por parte dos utilizadores de teste. No entanto, a maioria das medidas obtidas apresenta valores constantes ao longo de diversas utilizações, igualando os valores que seriam obtidos manualmente, mas com o potencial de os obter em metade do tempo. Pode concluir-se então que, no momento, a avaliação do alinhamento 3D é possível utilizando o software desenvolvido. É possível ainda apontar algumas limitações e fazer algumas sugestões de modo a que estas sejas ultrapassadas. Algumas limitações partiram do facto da experiência a programar em Python ser bastante limitada, e outras partiram do software utilizado para fazer o desenvolvimento. Por exemplo, o método que teria sido o mais indicado para encontrar um certo número de pontos na Tibia não foi possível de implementar devido a um bug interno do software. Existe ainda muita coisa que pode ser feita no que toca ao software desenvolvido e ao objectivo final de desenvolver um método de planeamento pré-operativo: em primeiro lugar, é necessário realizar mais testes, de modo a aumentar o tamanho da amostra e o intervalo de confiança dos testes; em segundo lugar, eliminar a dependência do Geomagic para utilizar o programa seria o ideal; finalmente, de modo a completar o plano inicial, deve ser implementada a possibilidade de visualizar o resultado da cirurgia nos modelos 3D.The lower limbs are responsible for supporting the body and are essential for several tasks such as standing, walking and running. Sometimes, and due to various reasons, defects or deformities can be found on the lower limbs and this has an impact on a person’s quality-of-life. One characteristic of the structure of the lower limb that is affected by these deformities is its alignment, i.e. the relative positions of the bones and joints that it includes. Thanks to the evolution of modern medicine, fixing these deformities is now a common practice in the orthopedics' surgical field. Before any corrective surgery and its respective planning, the deformity needs to be properly analyzed, which is accomplished by the assessment of the alignment of the whole lower limb. Currently, in clinical setting, this assessment is carried out manually in the two-dimensional space, normally using wholeleg X-ray images of the anatomical frontal plane, but complex deformities can not be assessed properly in a 2D image. In a desire to create an automatic computer-based method for the preoperative planning of deformity correction and knee surgery, a project consisting of developing a new software for assessing the lower limb alignment based on 3D models was proposed. The project was comprised of four stages: In the first stage, 3D models of different patients’ lower limbs were generated using both segmentation and 3D rendering software, and it was ensured that these models could be generated by any user without significant variability/error in the final outcome; In the second stage, the exact angles and measures needed for a proper assessment were defined, as well as the anatomic landmarks required to calculate them that should then be found by the software; During the third stage, the software development took place, from which resulted a program that uses the generated 3D models and, in the most automatic way possible and with an easy-to-use interface, returns all the needed angles and measures; The final stage of the project was to ensure that the program is reliable and consistent in its results in both intraobserver and interobserver domain, and that it composes an improvement when compared with the manual procedure, while also ensuring that the results obtained by using the program match those obtained manually. A lot can still be done and improved regarding the developed software and the ultimate goal of fully developing a preoperative planning method, but, so far, the 3D alignment assessment that results from the program has been considered to perform its task properly and in an improved way when compared to the traditional technique, even though some limitations can be observed

The winking sign is an indicator for increased femorotibial rotation in patients with recurrent patellar instability

Purpose: Rotation of the tibia relative to the femur was recently identified as a contributing risk factor for patellar instability, and correlated with its severity. The hypothesis was that in patellofemoral dysplastic knees, an increase in femorotibial rotation can be reliably detected on anteroposterior (AP) radiographs by an overlap of the lateral femoral condyle over the lateral tibial eminence. Methods: Sixty patients (77 knees) received low-dose computed tomography (CT) of the lower extremity for assessment of torsional malalignment due to recurrent patellofemoral instability. Three-dimensional (3D) surface models were created to assess femorotibial rotation and its relationship to other morphologic risk factors of patellofemoral instability. On weight-bearing AP knee radiographs, a femoral condyle/lateral tibial eminence superimposition was defined as a positive winking sign. Using digitally reconstructed radiographs of the 3D models, susceptibility of the winking sign to vertical/horizontal AP knee radiograph malrotation was investigated. Results: A positive winking sign was present in 30/77 knees (39.0%) and indicated a 6.3 ± 1.4° increase in femorotibial rotation (p 15°) with 43% sensitivity and 90% specificity (AUC = 0.72; p = 0.002). A positive winking sign (with 2 mm overlap) disappeared in case of a 10° horizontally or 15° vertically malrotated radiograph, whereas a 4 mm overlap did not disappear at all, regardless of the quality of the radiograph. In absence of a winking sign, on the other hand, no superimposition resulted within 20° of vertical/horizontal image malrotation. Femorotibial rotation was positively correlated to TT-TG (R2 = 0.40, p = 0.001) and patellar tilt (R2 = 0.30, p = 0.001). Conclusions: The winking sign reliably indicates an increased femorotibial rotation on a weight-bearing AP knee radiograph and could prove useful for day-by-day clinical work. Future research needs to investigate whether femorotibial rotation is not only a prognostic factor but a potential surgical target in patients with patellofemoral disorders. Level of evidence: III. Keywords: Femorotibial rotation; Knee rotation; Patellar instability; Winking sig

Biomechanical Investigations of Medial Opening Wedge High Tibial Osteotomy: Gait Analysis, Materials Testing and Dynamic Radiography

This thesis aimed to develop and assess biomechanical methods to assist in the evaluation of medial opening wedge high tibial osteotomy (HTO). Five studies using diverse methods were performed, including three-dimensional (3D) gait analysis, materials testing of HTO fixation plates, and dynamic radiography in patients after surgery. Study 1 compared external knee joint moments during walking before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants. The results highlighted the importance of alignment on gait biomechanics with changes in frontal plane angular impulse highly correlated to changes in mechanical axis. Study 2 compared the 3D external knee moments before and after medial opening wedge HTO during level walking and during stair ascent. Long-term changes in knee moments after HTO were observed during both activities, with decreases in the peak knee adduction and internal rotation moments. Study 3 developed and tested a multi-axis fixation jig placed within a materials testing machine for assessing HTO fixation plates in a manner more representative of walking. The need to incorporate gait data into materials testing studies was highlighted, showing the importance of including a frontal plane moment during testing. Study 4 used this multi-axis fixation jig to compare flat to toothed HTO fixation plates under cyclic loading conditions. Preliminary results suggested little difference in the load at failure between the plates; however, the potential for the tooth to increase micro-motion across the osteotomy site and strain on the lateral cortical hinge should be a focus of future testing. Study 5 was a proof-of-concept study to test dynamic single-plane flat-panel (FP) radiography for use in detecting in-vivo micro-motion after medial opening wedge HTO. Preliminary results suggested dynamic FP radiography has the potential to assess fixation stability; however, results also suggested modifications in the registration algorithms may be required to increase confidence in distinguishing true motion from registration error. Overall, this thesis demonstrates that a mix of biomechanical methods can be used to advance medial opening wedge HTO, with particular focus on informing future methods of investigation to improve HTO fixation designs

Custom-Made Devices Represent a Promising Tool to Increase Correction Accuracy of High Tibial Osteotomy: A Systematic Review of the Literature and Presentation of Pilot Cases with a New 3D-Printed System

Background: The accuracy of the coronal alignment corrections using conventional high tibial osteotomy (HTO) falls short, and multiplanar deformities of the tibia require consideration of both the coronal and sagittal planes. Patient-specific instrumentations have been introduced to improve the control of the correction. Clear evidence about customized devices for HTO and their correction accuracy lacks. Methods: The databases PUBMED and EMBASE were systematically screened for human and cadaveric studies about the use of customized devices for high tibial osteotomy and their outcomes concerning correction accuracy. Furthermore, a 3D-printed customized system for valgus HTO with three pilot cases at one-year follow-up was presented. Results: 28 studies were included. The most commonly used custom-made devices for HTO were found to be cutting guides. Reported differences between the achieved and targeted correction of hip-knee-ankle angle and the posterior tibial slope were 3 degrees or under. The three pilot cases that underwent personalized HTO with a new 3D-printed device presented satisfactory alignment and clinical outcomes at one-year follow-up. Conclusion: The available patient-specific devices described in the literature, including the one used in the preliminary cases of the current study, showed promising results in increasing the accuracy of correction in HTO procedure

STAGED MEDIAL OPENING WEDGE HIGH TIBIAL OSTEOTOMY FOR BILATERAL VARUS GONARTHROSIS

Background: Medial opening wedge high tibial osteotomy (HTO) aims to improve pain and function by correcting varus alignment and lessening aberrant medial compartment knee joint loads. Because varus gonarthrosis often affects both knees, staged bilateral HTO may be an appropriate treatment approach for such patients. However, we are unaware of any previous studies evaluating outcomes after these staged procedures. Objectives: 1) To evaluate radiographic alignment, dynamic knee joint loading, performance-based and patient-reported outcomes after staged bilateral medial opening wedge HTO, and 2) To compare outcomes in patients undergoing the second surgery within, or beyond, 12 months of the first surgery. Hypotheses: 1) Patients will experience statistically and clinically significant improvements in all measured outcomes; 2) Those patients undergoing the second surgery within 12 months of the first surgery will report greater improvements than those undergoing the second surgery beyond 12 months. Study Design: Case Series; Level of evidence, 4 Methods: 37 patients with bilateral varus alignment (-8.36° ± 2.98°) and medial compartment osteoarthritis (OA) underwent staged bilateral medial opening wedge HTO. Patients underwent full-limb standing anteroposterior radiographs to determine frontal plane alignment (mechanical axis angle) and 3-dimensional gait analysis to estimate knee joint loading (external adduction moment about the knee). Patients also completed the six-minute walk test (6MWT), the Knee Injury and Osteoarthritis Outcomes Scores (KOOS), Lower Extremity Functional Scale (LEFS), and the Short Form Health Survey [SF-12). Both limbs were evaluated for all measures preoperatively and approximately 6,12 and 24 months after each surgery. Results: There were large improvements in outcomes. Mean changes (95%CI) were: mechanical axis angle 9.43° (8.37°, 10.39°); peak knee adduction moment -1.72 %BW*Ht [-2.06, -1.38 %BW*Ht); 6MWT 36.72 m [19.43, 54.01m); and KOOS Pain 25.60 [19.76, 31.44). There were no statistically significant differences in the improvements between those patients who had the second HTO within or beyond 12 months of the first HTO. Mean differences [95% Cl) were: mechanical axis angle 0.43° [-1.72°, 2.58°); peak knee adduction moment -0.20 %BW*Ht [-0.89, 0.49 %BW*Ht); 6MWT 15. 07 m [-19.79, 49.93m); and KOOS Pain -3.01 [ -14.55, 8.53). Conclusions: Patients experience large, clinically important improvements in frontal plane alignment, dynamic knee joint loading, and patient-reported outcomes after staged bilateral medial opening wedge HTO. Current findings suggest no difference in outcomes for patients who undergo the second surgery within, or beyond, 12 months of the first surgery