Modeling and extraction of the articular cartilage

Tato disertační práce se zabývá modelováním a extrakcí artikulární chrupavky z obrazových dat MR (magnetické rezonance). V oblasti klinické diagnostiky artikulárních chrupavek je stěžejní přesná lokalizace chrupavky s ohledem na patologické procesy, které jsou často obtížně hodnotitelné, neboť jejich manifestace oproti fyziologické chrupavce je nekontrastní. Hodnocení chrupavek je často ovlivněno subjektivní chybou a je závislé na zkušenostech hodnotícího lékaře. Tato práce se zabývá designem multiregionální segmentační metodologie, která se opírá o dvoufázovou klasifikaci pixelů. V prvním kroku je řešen návrh jasové segmentační procedury, aproximující jednotlivé obrazové regiony pomocí posloupnosti fuzzy trojúhelníkovitých funkcí členství. Lokalizace těchto funkcí je řízena ABC (Artificial Bee Colony) algoritmem, který reprezentuje genetický evoluční proces. Druhá část metodologie se zabývá lokální agregační procedurou, která bere v úvahu prostorové relace pixelů a umožňuje modifikovat členskou funkci jasové klasifikace. Značnou výhodou takového systému je robustnost vůči šumovým pixelům a artefaktům, které v určité míře bývají přítomny v MR obrazových datech. Výstupem segmentační procedury je regionální model artikulární chrupavky, který spolehlivě reflektuje fyziologickou oblast artikulární chrupavky od lokací, kde dochází již k rané ztrátě chrupavky, která je obtížněji detekovatelná z nativních MR záznamů. Navrhovaná metoda byla rovněž testována na syntetických variabilních zdrojích obrazového šumu.This dissertation thesis deals with the modeling and extraction of the articular cartilage from the MR (magnetic resonance) image data. In an area of the articular cartilage clinical diagnostic, a precise localization of the articular cartilage is essential with regard to the pathological processes which are often badly evaluable due to their manifestation is non contrast in comparison with the physiological cartilage. The cartilage assessment is often affected by the subjective error, and it is depended on physician’s experience. This work is focused on a design of the multiregional segmentation methodology which is based on two-phase pixel classification. In the first step, a design of the brightness segmentation procedure is figured out approximating individual image regions by a sequence of the fuzzy triangular membership functions. A localization of those functions is driven by the ABC (Artificial Bee Colony) algorithm representing a genetic evolutionary process. The second part of the methodology deals with the local aggregation procedure taking into account spatial pixels relationships, and allows for a modification of the brightness classification membership function. A substantial benefit of such system is robustness against the noise pixels and artefacts which are presented in the MR image data. Output of the segmentation procedure is a regional model of the articular cartilage which reliably reflects the articular cartilage physiological area from locations of early cartilage loss. Such changes are badly detectable from the native MR data. The proposed method has been also tested on synthetic variable sources of the image noise.450 - Katedra kybernetiky a biomedicínského inženýrstvívyhově

Analysis, Segmentation and Prediction of Knee Cartilage using Statistical Shape Models

Osteoarthritis (OA) of the knee is one of the leading causes of chronic disability (along with the hip). Due to rising healthcare costs associated with OA, it is important to fully understand the disease and how it progresses in the knee. One symptom of knee OA is the degeneration of cartilage in the articulating knee. The cartilage pad plays a major role in painting the biomechanical picture of the knee. This work attempts to quantify the cartilage thickness of healthy male and female knees using statistical shape models (SSMs) for a deep knee bend activity. Additionally, novel cartilage segmentation from magnetic resonance imaging (MRI) and estimation algorithms from computer tomography (CT) or x-rays are proposed to facilitate the efficient development and accurate analysis of future treatments related to the knee. Cartilage morphology results suggest distinct patterns of wear in varus, valgus, and neutral degenerative knees, and examination of contact regions during the deep knee bend activity further emphasizes these patterns. Segmentation results were achieved that were comparable if not of higher quality than existing state-of-the-art techniques for both femoral and tibial cartilage. Likewise, using the point correspondence properties of SSMs, estimation of articulating cartilage was effective in healthy and degenerative knees. In conclusion, this work provides novel, clinically relevant morphological data to compute segmentation and estimate new data in such a way to potentially contribute to improving results and efficiency in evaluation of the femorotibial cartilage layer

Developing a cationic contrast agent for computed tomographic imaging of articular cartilage and synthetic biolubricants for early diagnosis and treatment of osteoarthritis

Osteoarthritis (OA) causes debilitating pain for millions of people, yet OA is typically diagnosed late in the disease process after severe damage to the articular cartilage has occurred and few treatment options exist. Furthermore, destructive techniques are required to measure cartilage biochemical and mechanical properties for studying cartilage function and changes during OA. Hence, research and clinical needs exist for non-destructive measures of cartilage properties. Various arthroscopic (e.g., ultrasound probes) and imaging (e.g., MRI or CT) techniques are available for assessing cartilage less destructively. However, arthroscopic methods are limited by patient anesthesia/infection risks and cost, and MRI is hindered by high cost, long image acquisition times and low resolution. Contrast-enhanced CT (CECT) is a promising diagnostic tool for early-stage OA, yet most of its development work utilizes simplified and ideal cartilage models, and rarely intact, pre-clinical animal or human models. To advance CECT imaging for articular cartilage, this dissertation describes further development of a new cationic contrast agent (CA4+) for minimally-invasive assessment of cartilage biochemical and mechanical properties, including glycosaminoglycan content, compressive modulus, and coefficient of friction. Specifically, CA4+ enhanced CT is compared to these three cartilage properties initially using an ideal bovine osteochondral plug model, then the technique is expanded to examine human finger joints and both euthanized and live mouse knees. Furthermore, CECT attenuations with CA4+ map bovine meniscal GAG content and distribution, signifying CECT can evaluate multiple tissues involved in OA. CECT's sensitivity to critical cartilage and meniscal properties demonstrates its applicability as both a non-destructive research tool as well as a method for diagnosing and monitoring early-stage OA. Additionally, CECT enables evaluation of efficacy for a new biolubricant (2M TEG) for early-stage OA treatment. In particular, CECT can detect the reduced wear on cartilage surfaces for samples tested in 2M TEG compared to samples tested in saline (negative control). With its sensitivity to cartilage GAG content, surface roughness, and mechanical properties, CA4+ enhanced CT will serve as a valuable tool for subsequent in vivo animal and clinical use

Visualisation of articular motion in orthopaedics

Shouder replacement surgery is difficult surgery, with a relatively large risk on limited post-operative range of motion for patients. Adaptations to the anatomy of joints by placing a prosthesis affects the articulation of the joint. In this thesis we present a software system that simulates and visualises these effects. By loading a CT-scan of the shoulder of a patient we can simulate the range of motion of the joint and visualize limitations as a result of rigid structures of the joint. Surgeons may set up an operation plan and see what the consequences of the operation will be for the range of motion of the patient. The thesis investigates aspects that are relevant for the system. We describe an algorithm to convert the scan data to bone models. In addition, a validation experiment is presented. A method for motion registration and visualisation of recorded kinematic data is presented. Finally, this thesis concerns the application of the system to different surgical problems, such as hip arthroplasty and shoulder fractures.Annafonds Biomet Nederland Clinical Graphics DePuy JTE Johnson & Johnson Dutch Arthritis Association Litos/ Motek Medical TornierUBL - phd migration 201

Quantitative Magnetic Resonance Imaging of Knee Articular Cartilage and Effusion-Synovitis: The Structural Response to Changes in Joint Loading

Knee osteoarthritis (OA) is a progressive degenerative condition that can affect all tissues within the joint. Methods to measure early changes in joint structures and the effect of interventions are required. The purpose of this thesis was to investigate aspects of quantitative magnetic resonance imaging (MRI) as outcome measures in knee OA studies. Specifically, changes in articular cartilage composition and/or effusion-synovitis were examined in people with or at risk for knee OA and healthy controls, and after altering joint loads. Chapter 2 is a systematic review that studied articular cartilage composition using MRI T2 and T1ρ relaxation in patients at risk for knee OA and healthy controls. We performed meta-analyses to examine the effect of knee OA risk factors on T2 and T1ρ relaxation. The presence of risk factors resulted in lengthened T2 and T1ρ relaxation. These findings support the use of compositional MRI to detect articular cartilage degeneration early in the OA disease process. Chapter 3 explores the acute response of knee articular cartilage T2 relaxation to a functional loading stimulus in patients at risk for knee OA and healthy controls. T2 relaxation shortened similarly in both groups following the loading stimulus. The loading stimulus evoked consistent changes in articular cartilage composition but did not detect compromised articular cartilage in patients at risk for knee OA. Chapter 4 evaluates the effect of high tibial osteotomy (HTO), a limb realignment surgery, on T2 relaxation of articular cartilage in patients with knee OA and varus alignment. Shortening of T2 relaxation was observed in the medial compartment, with no change in the lateral or patellar compartments, suggesting HTO can improve articular cartilage composition in the targeted compartment, without harming other compartments. Chapter 5 studies the effect of knee load on effusion-synovitis, using HTO as a model. The change in knee adduction impulse was associated with the change in effusion-synovitis. The findings suggest that mechano-inflammation is an active pathway in knee OA that can respond to biomechanical intervention. Overall, this thesis provides evidence that quantitative MRI is sensitive to structural changes of articular cartilage and effusion-synovitis at various stages of knee OA

Peripheral contributions to the development and maintenance of inflammation and pain in arthritis

Vascular endothelial growth factor A (VEGF-A) is a key regulator of vascular growth, permeability, and neuronal function. During articular inflammation in osteoarthritis (OA) and rheumatoid arthritis (RA), there is increased synovial angiogenesis and upregulation of angiogenic growth factors such as VEGF-A. VEGF-A comprises of two splice variant families, VEGF-Axxxa and VEGF-Axxxb (xxx represents the number of amino acids, from 121 to 206), resulting from alternative splice site selection in exon 8. Distal site selection and VEGF-Axxxa expression is controlled by Serine/Arginine Rich Splicing Factor Kinase 1 (SRPK1), which phosphorylates Serine/Arginine Rich Splicing Factor 1 (SRSF1), inducing its translocation to the nucleus. In most normal tissues, VEGF-Axxxb isoforms predominate, with anti-nociceptive and anti-angiogenic functions. In contrast, in pathological conditions such as inflammation and solid tumours SRPK1/SRSF1 activation causes VEGF-Axxxa isoforms to predominate, exerting pro-nociceptive and pro-angiogenic actions. VEGF-A has been proposed as a therapeutic target in OA. To date, a relation between VEGF-A and pain in OA has been reported, but there are no published data on the functionally distinct VEGF-A splice variants inflammation and pain in human OA and RA. This thesis examines the relationships between the expression of VEGF-A splicing isoforms and the components of the VEGF-A splicing axis, inflammation and pain in human sex, and macroscopic chondropathy-matched OA and RA synovial samples from total knee replacement and post-mortem donors. The expression and regulation of the VEGF-A splicing axis was examined by immunohistochemical staining for activated splicing factor SRSF1, splicing kinase SRPK1, total VEGF-A and the two families of VEGF-A splicing isoforms VEGF-Axxxa and VEGF-Axxxb. Protein expression was measured as the fractional area of staining (VEGF-A and isoforms, SRSF1, SRPK1 and Dyrk1A. SRSF1 activation was measured by the degree of nuclear localisation of SRSF1 compared to the total cell numbers in superficial synovium. According to principal component analysis structural abnormalities such as synovial thickening significantly contribute to the VEGF-Axxxb. Similarly, synovitis was positively correlated with the levels of SRSF1 and VEGF-A, but no alterations were documented regarding the two isoforms in relation to the synovitis. Expression of the related splicing kinase Dyrk1A, implicated in RA, was also positively related to the degree of inflammation. Nuclear SRSF1 was significantly correlated with inflammation score (r= 0.52, p<0.05). Total VEGF-A expression was significantly increased in RA compared to PM and OA (H (2) =23.3, p<0.001 RA cf. OA,PM; ;RA median=0.4, IQR(0.37,0.59); OA median=0.24, IQR(0.19,0.33);PM median=0.18, IQR(0.15,0.2) and was also correlated with the severity of inflammation (r=0.47 p<0.05). VEGF-Axxxb showed no change in expression in OA or RA, although VEGF-Axxxb staining intensity was significantly higher in RA samples, compared to controls (H (2) =7.2 p=0.02; RA median=2.3(1, 4); PM median=0.9 (0.7, 1.4). Similarly, symptomatic OA was associated with significantly increased SRPK1, SRSF1 and VEGF-A expression, while the VEGF-Axxxb isoform was significantly reduced. SRPK1 expression was similar across all conditions. SRSF1 showed significantly higher expression in the OA tissue compared to PM (H(2)= 11.29, p=0.002; OA median=0.2, IQR(0.15, 0.28); PM median=0.09, IQR(0.07, 0.16)), and significantly higher nuclear localisation (indicating activation) in RA vs. OA, and in both RA and OA vs PM (H(2)=37.65, p<0.0001 RA cf. PM; p=0,007 OA cf. PM; RA median=89, IQR(83, 93); OA median=36.1, IQR(29, 42); PM median=19.8, IQR(14,21)). Nuclear SRSF1 was significantly correlated with inflammation score (r= 0.52, p<0.05). Total VEGF-A expression was significantly increased in RA compared to PM and OA (H (2) =23.3, p<0.001 RA cf. OA,PM; ;RA median=0.4, IQR(0.37,0.59); OA median=0.24, IQR(0.19,0.33);PM median=0.18, IQR(0.15,0.2)) and was also correlated with the severity of inflammation (r=0.47 p<0.05). VEGF-Axxxb showed no change in expression in OA or RA, although VEGF-Axxxb staining intensity was significantly higher in RA samples, compared to controls (H (2) =7.2 p=0.02; RA median=2.3(1, 4); PM median=0.9 (0.7, 1.4)). Cultures of human primary fibroblast-like synoviocytes (FLS) were stimulated with tumour necrosis factor-α, and the effects on SRPK1, SRSF1 and VEGF-A expression were determined. An in vitro model of synovial inflammation, using fluorescently labelled THP1 monocytes and was used to determine the effect of VEGF-A, VEGF receptor tyrosine kinase inhibitors, and SRPK1 inhibition on monocyte adherence to an FLS monolayer. Alteration of splicing kinases CLK1-4 and DYRK1a with T-025 was able to significantly increase SRSF1 mRNA expression, and I also confirmed the presence of VEGF-A mRNA in HFLS, however, no splice variants could be detected. These results indicate that the VEGF-A expression and splicing axis is altered in relation to both inflammation and pain, but in distinct ways. I present evidence that inhibition of VEGF-A splicing controls could affect both inflammation, such as in OA flares, and pain in OA

Biotribology of the Natural Ankle Joint

The ankle joint is a stable and congruent joint that helps to protect the joint surfaces from high impact forces. However, possible trauma to the joint such as severe ankle sprain or fracture can cause cartilage breakdown and eventually lead to cartilage degeneration, resulting in arthritis. Ankle arthritis is considered to be a major cause of morbidity and disability. Although the ankle joint is least affected by arthritis compared to knee and hip joints, the pain and lack of mobility of end stage ankle osteoarthritis (OA) are equally debilitating and tend to be overlooked compared to hip and knee OA. Differences in the incidence rates of osteoarthritis (OA) across the joints could be partly attributed to the biomechanical properties of the articular cartilage. The aim of the thesis was to improve the understanding of mechanical characteristics of the human ankle cartilage through developing and refining methodologies (i.e. indentation and thickness methods) on immature porcine ankle tissues. As porcine ankle joint seems to closely represent the human ankle with comparable anatomical features, cartilage deformation, cartilage thickness, coefficient of friction, surface roughness, contact mechanics and biological properties were also determined. Comparisons of mechanical characteristics between porcine and human tissues were reported. A methodology was developed to identify the most suitable type of specimen (osteochondral samples versus whole joints) for mechanical characterisation as specimen preparation via pin extraction was hypothesised to have an effect on the tissue quality and thus on biomechanical properties. Specimen preparation of osteochondral pins had no impact on properties as cartilage deformation and thickness measurements of pins were comparable to whole joints. Therefore, for mechanical characterisation of human ankle cartilage, osteochondral pins were studied. Porcine talar cartilage was found to be thicker, with higher surface roughness, increased water content, increased contact pressures and lower glycosaminoglycan (GAG) content compared to porcine tibial cartilage. Based on such results, the talar cartilage in the young porcine tissue (3 to 6 months) appeared more susceptible to deterioration over time when compared to tibial cartilage as these properties were considered as unfavourable potentially affecting joint function and quality of tissue during high impact forces. Overall, there were significant differences in thickness, deformation and roughness measurements (ANOVA, p<0.05 for all comparators) across the porcine and human tissues. These differences between animal and human tissues can be attributed to many factors such as age, gait, lifestyle and mechanical properties. The immature porcine cartilage was considered to be a poor representative model for tribological studies. On the human ankle joint, cartilage thicknesses, deformation and surface roughness measurements were all in a comparable range between talar and tibial joint surfaces (ANOVA, p<0.05 for all comparators). Although ankle lesions were reported to be commonly found in the talar surface rather than the tibial surface, and it was assumed to result in unfavourable properties, this was not reported in the current study as no significance was observed between both joint surfaces

Osteoarthritis: pathogenesis and therapeutic interventions for a whole joint disease

__Abstract__ Osteoarthritis (OA) is an invalidating disease characterized by progressive cartilage degradation. OA is the most prevalent arthritic disease and leading cause of disability that effects approximately 34% of the population in the United states over age 65. Also in the Netherlands, approximately 30% of persons aged 65 and older are affected in either the hip or knee joint by this severely disabling disease. Due to the obvious cartilage pathology, research has much focused on articular cartilage and chondrocyte pathobiology. Over the years more knowledge has been gained on complex biochemical and biomechanical influences of chondrocyte behavior. During the past decade, however, pathologic cellular and structural changes in subchondral and trabecular bone, ligaments, synovium, supporting musculature, fibrocartilagenous structures such as the meniscus, and intra-articular fat tissue support the idea that osteoarthritis is not just a cartilage problem. In the current dogma, OA is explained as ‘a whole joint disease’ that involves a degenerative continuum between multiple joint tissues and cell types

Peripheral contributions to the development and maintenance of inflammation and pain in arthritis

Vascular endothelial growth factor A (VEGF-A) is a key regulator of vascular growth, permeability, and neuronal function. During articular inflammation in osteoarthritis (OA) and rheumatoid arthritis (RA), there is increased synovial angiogenesis and upregulation of angiogenic growth factors such as VEGF-A. VEGF-A comprises of two splice variant families, VEGF-Axxxa and VEGF-Axxxb (xxx represents the number of amino acids, from 121 to 206), resulting from alternative splice site selection in exon 8. Distal site selection and VEGF-Axxxa expression is controlled by Serine/Arginine Rich Splicing Factor Kinase 1 (SRPK1), which phosphorylates Serine/Arginine Rich Splicing Factor 1 (SRSF1), inducing its translocation to the nucleus. In most normal tissues, VEGF-Axxxb isoforms predominate, with anti-nociceptive and anti-angiogenic functions. In contrast, in pathological conditions such as inflammation and solid tumours SRPK1/SRSF1 activation causes VEGF-Axxxa isoforms to predominate, exerting pro-nociceptive and pro-angiogenic actions. VEGF-A has been proposed as a therapeutic target in OA. To date, a relation between VEGF-A and pain in OA has been reported, but there are no published data on the functionally distinct VEGF-A splice variants inflammation and pain in human OA and RA. This thesis examines the relationships between the expression of VEGF-A splicing isoforms and the components of the VEGF-A splicing axis, inflammation and pain in human sex, and macroscopic chondropathy-matched OA and RA synovial samples from total knee replacement and post-mortem donors. The expression and regulation of the VEGF-A splicing axis was examined by immunohistochemical staining for activated splicing factor SRSF1, splicing kinase SRPK1, total VEGF-A and the two families of VEGF-A splicing isoforms VEGF-Axxxa and VEGF-Axxxb. Protein expression was measured as the fractional area of staining (VEGF-A and isoforms, SRSF1, SRPK1 and Dyrk1A. SRSF1 activation was measured by the degree of nuclear localisation of SRSF1 compared to the total cell numbers in superficial synovium. According to principal component analysis structural abnormalities such as synovial thickening significantly contribute to the VEGF-Axxxb. Similarly, synovitis was positively correlated with the levels of SRSF1 and VEGF-A, but no alterations were documented regarding the two isoforms in relation to the synovitis. Expression of the related splicing kinase Dyrk1A, implicated in RA, was also positively related to the degree of inflammation. Nuclear SRSF1 was significantly correlated with inflammation score (r= 0.52, p<0.05). Total VEGF-A expression was significantly increased in RA compared to PM and OA (H (2) =23.3, p<0.001 RA cf. OA,PM; ;RA median=0.4, IQR(0.37,0.59); OA median=0.24, IQR(0.19,0.33);PM median=0.18, IQR(0.15,0.2) and was also correlated with the severity of inflammation (r=0.47 p<0.05). VEGF-Axxxb showed no change in expression in OA or RA, although VEGF-Axxxb staining intensity was significantly higher in RA samples, compared to controls (H (2) =7.2 p=0.02; RA median=2.3(1, 4); PM median=0.9 (0.7, 1.4). Similarly, symptomatic OA was associated with significantly increased SRPK1, SRSF1 and VEGF-A expression, while the VEGF-Axxxb isoform was significantly reduced. SRPK1 expression was similar across all conditions. SRSF1 showed significantly higher expression in the OA tissue compared to PM (H(2)= 11.29, p=0.002; OA median=0.2, IQR(0.15, 0.28); PM median=0.09, IQR(0.07, 0.16)), and significantly higher nuclear localisation (indicating activation) in RA vs. OA, and in both RA and OA vs PM (H(2)=37.65, p<0.0001 RA cf. PM; p=0,007 OA cf. PM; RA median=89, IQR(83, 93); OA median=36.1, IQR(29, 42); PM median=19.8, IQR(14,21)). Nuclear SRSF1 was significantly correlated with inflammation score (r= 0.52, p<0.05). Total VEGF-A expression was significantly increased in RA compared to PM and OA (H (2) =23.3, p<0.001 RA cf. OA,PM; ;RA median=0.4, IQR(0.37,0.59); OA median=0.24, IQR(0.19,0.33);PM median=0.18, IQR(0.15,0.2)) and was also correlated with the severity of inflammation (r=0.47 p<0.05). VEGF-Axxxb showed no change in expression in OA or RA, although VEGF-Axxxb staining intensity was significantly higher in RA samples, compared to controls (H (2) =7.2 p=0.02; RA median=2.3(1, 4); PM median=0.9 (0.7, 1.4)). Cultures of human primary fibroblast-like synoviocytes (FLS) were stimulated with tumour necrosis factor-α, and the effects on SRPK1, SRSF1 and VEGF-A expression were determined. An in vitro model of synovial inflammation, using fluorescently labelled THP1 monocytes and was used to determine the effect of VEGF-A, VEGF receptor tyrosine kinase inhibitors, and SRPK1 inhibition on monocyte adherence to an FLS monolayer. Alteration of splicing kinases CLK1-4 and DYRK1a with T-025 was able to significantly increase SRSF1 mRNA expression, and I also confirmed the presence of VEGF-A mRNA in HFLS, however, no splice variants could be detected. These results indicate that the VEGF-A expression and splicing axis is altered in relation to both inflammation and pain, but in distinct ways. I present evidence that inhibition of VEGF-A splicing controls could affect both inflammation, such as in OA flares, and pain in OA