482 research outputs found
The effect of weight-bearing positions on coronal lower limb alignment: A systematic review
No full textBACKGROUND: The coronal alignment of the lower limb is generally accepted as a major determinant of surgical outcome in total knee arthroplasty (TKA). To achieve the ideal post-operative alignment, surgeons need to be aware of the influence that weight-bearing positions have on the final knee alignment. Therefore, this review aims to define the effect of varying weight-bearing positions on the coronal alignment of the lower limb. We hypothesized that a coronal alignment deformity increases with loading. METHODS: The PubMed, Medline and google scholar databases were searched systematically in June 2022. Only studies which compared coronal alignment with a standardized radiographic protocol in the single leg, double leg and supine positions were included. To obtain pooled estimates of the effect of different weight-bearing positions, random-effect analysis were fitted using SAS. RESULTS: Compared to the supine position, double leg weight-bearing positions were found to be associated with a more pronounced varus deformity (mean difference in HKA is 1,76° (95% CI 1,32: 2,21), p < 0.0001)). The mean difference in HKA between double leg and single leg weight-bearing conditions was 1.43° (95% CI (-0,042;2,90), p = 0.0528). CONCLUSION: The overall knee alignment was found to be influenced by the weight-bearing position. An average difference of 1.76° in HKA-angle was found between a double leg-stance and supine position, tending to increased varus in the former weight-bearing position. It is therefore possible that the deformity could increase by 1.76° if knee surgeons only follow a pre-op planning based on double-leg stance full length radiographs.sponsorship: This study is part of Limburg Clinical Research Center supported by Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital. (Limburg Clinical Research Center - Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital)status: Publishe
Microstructural adaptations of the subchondral bone are related to the mechanical axis deviation in end stage varus OA knees
No full textRecent studies highlighted the crucial contribution of subchondral bone to OA development. Yet, only limited data have been reported on the relation between alteration to cartilage morphology, structural properties of the subchondral bone plate (SBP) and underlying subchondral trabecular bone (STB). Furthermore, the relationship between the morphometry of the cartilage and bone in the tibial plateau and the OA-induced changes in the joint's mechanical axis remains unexplored. Therefore, a visualisation and quantification of cartilage and subchondral bone microstructure in the medial tibial plateau was performed. End stage knee-OA patients with varus alignment and scheduled for total knee arthroplasty (TKA) underwent preoperative fulllength radiography to measure the hip-knee-ankle angle (HKA) and the mechanical-axis deviation (MAD). 18 tibial plateaux were μ-CT scanned (20.1 μm/voxel). Cartilage thickness, SBP, and STB microarchitecture were quantified in 10 volumes of interest (VOIs) in each medial tibial plateau. Significant differences (p < 0.001) were found for cartilage thickness, SBP, and STB microarchitecture parameters among the VOIs. Closer to the mechanical axis, cartilage thickness was consistently smaller, while SBP thickness and STB bone volume fraction (BV/TV) were higher. Moreover, trabeculae were also more superior-inferiorly oriented, i.e. perpendicular to the transverse plane of the tibial plateau. As cartilage and subchondral bone changes reflect responses to local mechanical loading patterns in the joint, the results suggested that region-specific subchondral bone adaptations were related to the degree of varus deformity. More specifically, subchondral sclerosis appeared to be most pronounced closer to the mechanical axis of the knee.sponsorship: This study was part of Limburg Clinical Research Centre supported by Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital and was fundedin part by KU Leuven Internal Funds, Grant C24/16/027?. (Hasselt University, Ziekenhuis Oost-Limburg, Jessa Hospital, KU Leuven Internal Funds|C24/16/027?)status: Published onlin
Correlation between tibial and femoral bone and cartilage changes in end-stage knee osteoarthritis
No full textKnee osteoarthritis is a whole joint disease highlighting the coupling of cartilage and bone adaptations. However, the structural properties of the subchondral bone plate (SBP) and underlying subchondral trabecular bone (STB) in the femoral compartment have received less attention compared to the tibial side. Furthermore, how the properties in the femoral compartment relate to those in the corresponding tibial site is unknown. Therefore, this study aimed to quantify the structural bone and cartilage morphology in the femoral compartment and investigate its association with those of the tibial plateau. Specifically, tibial plateaus and femoral condyles were retrieved from 28 patients with end-stage knee-osteoarthritis (OA) and varus deformity. The medial condyle of tibial plateaus and the distal part of the medial femoral condyles were micro-CT scanned (20.1 mu m/voxel). Cartilage thickness (Cart.Th), SBP, and STB microarchitecture were quantified. Significant (P < <.001; 0.79 <= r <= 0.97) correlations with a relative difference within 10% were found between the medial side of the femoral and tibial compartments. The highest correlations were found for SBP porosity (r = 0.97, mean absolute difference of 0.50%, and mean relative difference of 9.41%) and Cart.Th (r = 0.96, mean absolute difference of 0.18 mm, and relative difference of 7.08%). The lowest correlation was found for trabecular thickness (r = 0.79, mean absolute difference of 21.07 mu m, and mean relative difference of 5.17%) and trabecular number (r = 0.79, mean absolute difference of 0.18 mm-(1), and relative difference of 5.02%). These findings suggest that the distal femur is affected by OA in a similar way as the proximal tibia. Given that bone adaptation is a response to local mechanical forces, our results suggest that varus deformity similarly affects the stress distribution of the medial tibial plateau and the medial distal femur.This study is part of Limburg Clinical Research Center supported by Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital and was funded in part by KU Leuven Internal Funds (C24/16/027) and by the FWO and F.R.S.-FNRS under the Excellence of Science (EOS) programme (EOS No. 40007553)
The anterolateral ligament has similar biomechanical and histological properties as the inferior glenohumeral ligament
No full textPURPOSE: To characterize the tensile and histologic properties of the anterolateral ligament (ALL), inferior glenohumeral ligament (IGHL), and knee capsule. METHODS: Standardized samples of the ALL (n = 19), anterolateral knee capsule (n = 15), and IGHL (n = 13) were isolated from fresh-frozen human cadavers for uniaxial tensile testing to failure. An additional 6 samples of the ALL, capsule, and IGHL were procured for histologic analysis and determination of elastin content. RESULTS: All investigated mechanical properties were significantly greater for both the ALL and IGHL when compared with capsular tissue. In contrast, no significant differences between the ALL and IGHL were found for any property. The elastic modulus of ALL and IGHL samples was 174 ± 92 MPa and 139 ± 60 MPa, respectively, compared with 62 ± 30 MPa for the capsule (P = .001). Ultimate stress was significantly lower (P < .001) for the capsule, at 13.4 ± 7.7 MPa, relative to the ALL and IGHL, at 46.4 ± 20.1 MPa and 38.7 ± 16.3 MPa, respectively. The ultimate strain at failure was 37.8% ± 7.9% for the ALL and 39.5% ± 9.4% for the IGHL; this was significantly greater (P = .041 and P = .02, respectively) for both relative to the capsule, at 32.6% ± 8.4%. The strain energy density was 7.8 ± 3.1 MPa for the ALL, 2.1 ± 1.3 MPa for the capsule, and 7.1 ± 3.1 MPa for the IGHL (P < .001). The ALL and IGHL consisted of collagen bundles aligned in a parallel manner, containing elastin bundles, which was in contrast to the random collagen architecture noted in capsule samples. CONCLUSIONS: The ALL has similar tensile and histologic properties to the IGHL. The tensile properties of the ALL are significantly greater than those observed in the knee capsule. CLINICAL RELEVANCE: The ALL is not just a thickening of capsular tissue and should be considered a distinct ligamentous structure comparable to the IGHL in the shoulder. The tensile behavior of the ALL is similar to the IGHL, and treatment strategies should take this into account.sponsorship: The authors report the following potential conflicts of interest or sources of funding: Study partially funded by Belgische Vereniging voor Orthopedie en Traumatologie. (Belgische Vereniging voor Orthopedie en Traumatologie)status: Publishe
Het orthopedisch onderzoeks- en trainingsinstituut
No full texthttps://www.uzleuven.be/nl/iortstatus: Published onlin
Changes in coronal knee-alignment parameters during the osteoarthritis process in the varus knee
No full textObjectives: The idea to aim for an "individualized" alignment, whereby the constitutional alignment is restored, has gained much interest among knee surgeons. This requires insight into the prediseased, natural alignment of our patients' knees. The aim of this study is (1) to determine how the hip-knee-ankle (HKA) angle is influenced during the arthritic process and (2) to investigate the correlation between joint line changes and the progression of osteoarthritis (OA). It is our hypothesis that the most pronounced coronal parameter changes appear at the proximal tibia and at the joint line. Methods: One hundred sequential full-length X-rays with a minimum follow-up of 1 year were retrospectively reviewed from a radiographic joint database. Patients had to be at least 50 years of age needed to have an HKA angle of more than 1.3 degrees varus to be included. Patients with ipsilateral total hip arthroplasty, femoral or tibial fracture, osteotomy, or ligamentous repair were excluded. Fifteen alignment parameters were investigated on the sequential full-length X-rays. Moreover, the relationship between the alignment parameters and the Kellgren-Lawrence grade (KL grade) was determined by using linear mixed models. Results: A progressive KL grade is associated with an increase of the HKA (p < 0.001). Mostly, HKA differs due to decrease of the medial tibial plateau (MPTA) angle (0.93 degrees) and an increase of the joint line angle (JLCA) (0.86 degrees). The mLDFA demonstrated the most pronounced changes in the beginning of OA (KL grade 1-2) (p = 0.049). In particular, the MPTA becomes considerably smaller (p = 0.004) in the later stage of OA (KL grade 3). Also, a progressive increase of the JLCA (p < 0.001) is observed upwards of KL grade 3. Conclusion: By comparing consecutive full-length X-rays in the same patients, it is possible to define the coronal alignment changes during the arthritic process. The HKA angle increases according the arthritic progression, whereby the most pronounced changes appear at the proximal tibia (MPTA) and at the joint line (JLCA).The alignment changes in varus OA knees can be divided in three stadia: (1) erosion of the distal medial femoral condyle, (2) erosion of the medial tibial plateau, and (3) a progressive increase of the joint line angle. Level of evidence: Therapeutic Study, Level III.The authors wish to acknowledge Dr. Elizabeth Flesher for her help in reviewing and revising the manuscript for grammar and syntax
2D en 3D ultrasone beeldvorming met hoge spatiële en temporele resolutie voor karakterisering van peesmechanica Een aanpak via beeldregistratie
No full textAchilles tendinopathy affects competitive and recreational athletes as well as inactive people. The incidence of this pathology in the general population is 1.8%and over 80% of tendon ruptures occur during recreational sports. The etiology of tendinopathies is multifactorial, but tendon overuse is assumed to be one of the main pathological stimuli.
Recently published studies have demonstrated the need for a better characterization of the tendon, more specifically, the local tendon mechanics. By performing this characterization in an accurate and reproducible manner, it isexpected to understand better the mechanical behaviour of healthy tendons and, consequently, better understand the tendinopathy pathogenesis.
Nowadays, characterization of tendon mechanics is done by estimating the global tendon strain and the local tendon tissue displacement. Conventional ultrasonography (6-10MHz) is the imaging modality used for this characterization due to its ubiquitous application for tendinopathy diagnosis and easy accessibility. However, it is believed that conventional ultrasonography is limited due to its low spatial and low temporal image resolution. Furthermore, the high-variability of tendon strain estimations reported in the literature are also assumed to be dependent on the imaging system used for the characterization of the tendon mechanics.
This work presented the investigation of the implementation of a 2D highspatial and high-temporal resolution ultrasound acquisition system for the in-vivo characterization of tendon mechanics. Due to the novelty of this type of acquisition system for tendon strain estimations, a validation step was initially designed. For this validation, 2D global strain estimations were calculated using a developed affine image registration method. Good performance was obtained for this validation step, which allowed the validation of the image registration method as well as the validation of the novel high-spatial and high-temporal resolution ultrasound acquisition system. Afterwards, a 2D deformable image registration method was developed for the in-vivo characterization of the local tendon mechanics. Local tendon mechanics was evaluated by estimating regional tendon strain and local tendon tissue displacement. The developed deformable image registration method and the calculation of the features used for the characterization of the local tendon mechanics were embedded in the KULTeC. The KULTeC is a standalone, easy and intuitive application, which is intended to allow the clinician to easily characterized the local tendon mechanics. Due to the absence of ground-truth for the in-vivo data, a psychometric approach was performed. The obtained results confirmed the reproducibility of the implemented deformable image registration method, demonstrated a convergence of the estimated results with the literature results and demonstrated the capability of the method for the discrimination between asymptomatic and medium to severe tendinopathy conditions.
After the in-vivo characterization of the local tendon mechanics, the impact of out-of-plane motion was investigated. This type of artifact, which affects every 2D imaging modality, has frequently been pointed out as tendon strain estimation errors. For this investigation, 3D high-spatial resolution ultrasound data was used, and the global strain was estimated using an affine image registration approach. The results obtained from this experiment, using in-silico data, demonstrated the theoretically added value of strain estimations using 3D data. However, with the increasing complexity of in-vitro and ex-vivo data, and the increasing complexity of the acquisition setup, the acquisition of 3D high-spatial resolution US images becomes very challenging.
In conclusion, this work demonstrates the successful implementation of 2D high-spatial and high-temporal resolution ultrasonography system for in-vivo characterization of the local tendon mechanics. The high-spatial and high-temporal resolution provided by the used acquisition system together with the developed deformable image registration method have the potential of allowing better and more accurate in-vivo characterization of local tendon mechanics. Furthermore, the developed KULTeC application allows an easy and intuitive use of the developed image registration method in the clinical practice. The results obtained for 3D high-spatial resolution ultrasonography for global strain estimations show that this modality has the potential for elimination of out-of-plane motion but its application to real-world conditions is still technically challenging.status: Publishe
Voor 't gewone leven ongeschikt. Een biografie van Clare Lennart
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Voor ’t gewone leven ongeschikt. A biography of Clare Lennart, is a literary and historical biography of author Clare Lennart (Clara Helena van den Boogaard-Klaver, 1889-1972). Her work contains many recognisably autobiographical elements, especially from her youth. An extensive overview of the life of this 'forgotten author' is the basis for this critical and interpretive biography. In addition it shows Clare Lennart's unique position in her time, the unusual choices she made and ‘the roads not taken’ in her life. The main focus of the research is the question of how Clare Lennart gained an economic position as a woman of letter. A second question focuses on the concepts of posture and self-fashioning. The thesis demonstrates that Clare Lennart was aware of her image as a 'poetic nature lover' and that she openly presented herself as a hack writer. Clare Lennart's poetic style nowadays seems more dated than the sober language used by contemporary authors. Nevertheless, she had a large audience between 1945 and 1972 and the reception was nearly always positive. The biography discusses the contemporary reception of her work in detail and why Clare Lennart's work is omitted from the Dutch canon, using the concept of ‘middle-brow’ literature.Modern and Contemporary Studie
Dataset supporting a publication "Protein–ligand free energies of binding from full-protein DFT calculations: convergence and choice of exchange–correlation functional".
No full textThis Dataset is made in two parts that provide input and output files for the publication: https://doi.org/10.1039/D1CP00206F
"Protein-ligand free energies of binding from full-protein DFT calculations: convergence and choice of exchange-correlation functional" .
Corresponding author: C.K Skylaris, [email protected]
Explanations of files present in README file in each subdirectory</span
idX Information Design Exchange. What information designers know and can do
No full textStrand, Lennart (2007). Co-author: idX Information Design Exchange. What information designers know and can do. "Development of International Core Competencies and Student and Faculty Exchange in Information Design" within the EU/US Cooperation Programme in Higher Education and Vocational Education and Training Outcome. Developed in co-operation with International Institute for Information Design, http://www.iiid.net/</p
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