optical-sectioning-visualization-intervertebral-disc-from-embryonic

Optical Sectioning and Visualization of the Intervertebral Disc from Embryonic Development to Degeneration

Intervertebral disc (IVD) degeneration is a leading cause of low back pain and it entails a high degree of impairment for the affected individuals. To ...

5-aminolevulinic-acid-mediated-photodynamic-therapy-on-primary-bone

5-Aminolevulinic Acid-mediated Photodynamic Therapy on Primary Bone Tumor and Bone Metastases Cell Lines

Bone metastases are associated with poor prognosis and low quality of life for the affected patients. Photodynamic therapy (PDT) emerges as a noninvasive ...

University Hospital of Tübingen

Several quantitative methods for the in vitro characterization of cartilage quality are available. However, only a few of these methods allow surgical cartilage manipulations and the subsequent analysis of the friction properties of complete joints. This study introduces an alternative approach to the characterization of the friction properties of entire joint surfaces using the dissipated energy during motion of the joint surfaces. Seven sheep wrist joints obtained post mortem were proximally and distally fixed to a material testing machine. With the exception of the carpometacarpal articulation surface, all joint articulations were fixed with 'Kirschner' wires. Three cartilage defects were simulated with a surgically introduced groove (16 mm(2), 32 mm(2), 300 mm(2)) and compared to intact cartilage without an artificial defect. The mean dissipated energy per cycle was calculated from the hysteresis curve during ten torsional motion cycles (±10°) under constant axial preload (100-900 N). A significant increase in dissipated energy was observed with increasing cartilage defect size and axial load (p<0.001). At lower load levels, the intact and 16 mm(2) defect showed a similar dissipated energy (p>0.073), while all other defect conditions were significantly different (p=0.015). All defect sizes were significantly different (p=0.049) at 900 N axial load. We conclude that the method introduced here could be an alternative for the study of cartilage damage, and further applications based on the principles of this method could be developed for the evaluation of different cartilage treatments.

Dissipated energy as a method to characterize the cartilage damage in large animal joints: an in vitro testing model.

Osteochondral autologous transplantation is frequently used to repair small cartilage defects. Incongruence between the osteochondral graft surface and the adjacent cartilage leads to changed friction and contact pressure. The present study wanted to analyze the differences between intact and surgically treated cartilage surface in respect to contact pressure and frictional characteristic (dissipated energy). Six ovine carpometacarpal joints were used in the present study. Dissipated energy during instrumentally controlled joint movement as well as static contact pressure were measured in different cartilage states (intact, defect, deep-, flush-, high-implanted osteochondral graft and cartilage failure simulation on a high-implanted graft). The best contact area restoration was observed after the flush implantation. However, the dissipated energy measurements did not reveal an advantage of the flush implantation compared to the defect and deep-implanted graft states. The high-implanted graft was associated with a significant increase of the mean contact pressure and decrease of the contact area but the dissipated energy was on the level of intact cartilage in contrast to other treatments where the dissipated energy was significantly higher as in the intact state. However the cartilage failure simulation on the high-implanted graft showed the highest increase of the dissipated energy. 

Changes in dissipated energy and contact pressure after osteochondral graft transplantation.

Although a person's fitness to drive has gained more attention over the past few years, investigations have focused mainly on postsurgical (eg, hip arthroplasty) driving performance. Few data are available on how orthoses affect the ability to perform an emergency stop.

The Effects of Hip and Spine Orthoses on Braking Parameters: A Simulated Study With Healthy Subjects.

Anterior knee pain is often associated with patellar maltracking and instability. However, objective measurement of patellar stability under clinical and experimental conditions is difficult, and muscular activity influences the results. In the present study, a new experimental setting for in vitro measurement of patellar stability was developed and the mediolateral force-displacement behavior of the native knee analyzed with special emphasis on patellar tilt and muscle loading.

Robot-aided in vitro measurement of patellar stability with consideration to the influence of muscle loading.

Imaging results are frequently considered as hallmarks of disease by spine surgeons to plan their future treatment strategy. Numerous classification systems have been proposed to quantify or grade lumbar magnetic resonance imaging (MRI) scans and thus objectify imaging findings. The clinical impact of the measured parameters remains, however, unclear. To evaluate the pathological significance of imaging findings in patients with multisegmental degenerative findings, clinicians can perform image-guided local infiltrations to target defined areas such as the facet joints. The aim of the present retrospective study was to evaluate the correlation of MRI facet joint degeneration and spinal stenosis measurements with improvement obtained by image-guided intraarticular facet joint infiltration.

Predictability of the effects of facet joint infiltration in the degenerate lumbar spine when assessing MRI scans.

A type VI collagen-rich pericellular matrix (PCM) encloses both intervertebral disk (IVD) and articular cartilage chondrocytes. In the latter, the PCM protects the chondrocytes from mechanical overload, whereas tissue degeneration is associated with PCM destruction. As little is known about the IVD PCM, we investigated chondrocyte survival after mechanical overload as well as PCM structural integrity as a function of clinical tissue degeneration. The hypothesis was that IVD degeneration may affect PCM integrity and overload-related chondrocyte survival. Cylindrical human IVD explants from patients undergoing surgical procedures for lumbar disk degeneration, disk prolapse, or spinal trauma were generated and scored. Mechanical overload was applied by single uniaxial 50% compression followed by immediate release, and the explants were live-dead stained (n = 20 explants). Type VI collagen, the major PCM component, was fluorescent stained and the extent was determined, in which individual cells were enclosed by a recognizable PCM; this was termed PCM fraction. More than 50% of chondrocytes in all degenerative IVD explants displayed <25% PCM fraction and a lower PCM fraction correlated with higher cell numbers (p < 0.001), suggesting a PCM structural impairment in IVD degeneration that is associated with chondrocyte clustering. Mechanical overload-induced significantly increased cell death (p = 0.005), and the PCM fraction was significantly lower in overload-induced cell death than in live cells (p = 0.042), suggesting that a fully present PCM has a protective role in mechanical overload. Collectively, human IVD degeneration is associated with a structural impairment of the PCM, which may promote cell death under mechanical overload.

Chondrocyte death after mechanically overloading degenerated human intervertebral disk explants is associated with a structurally impaired pericellular matrix.

Numerous classification systems have been proposed to analyze lumbar spine MRI scans. When evaluating these systems, most studies draw their conclusions from measurements of experienced clinicians. The aim of this study was to evaluate the impact of specific measurement training on interobserver reliability in MRI classification of the lumbar spine.

Interobserver Reliability When Classifying MR Imaging of the Lumbar Spine: Written Instructions Alone Do Not Suffice.

Numerous classification systems have been proposed to interpret lumbar MRI scans. The clinical impact of the measured parameters remains unclear. To evaluate the clinical significance of imaging results in patients with multisegmental degenerative pathologies, treating specialists can perform image-guided local injections to target defined areas such as the epidural space.

Predictability of the effects of epidural injection in lumbar spinal stenosis by assessment of lumbar MRI scans.

Lateral tibial split fractures (LTSF) usually require surgical therapy with screw or plate osteosynthesis. Excellent anatomical reduction of the fracture is thereby essential to avoid post-traumatic osteoarthritis. In clinical practice, a gap and step of 2 mm have been propagated as maximum tolerable limit. To date, biomechanical studies regarding tibial fractures have been limited to pressure measurement, but the relationship between dissipated energy (DE) as a friction parameter and reduction accuracy in LTSF has not been investigated. In past experiments, we developed a new method to measure DE in ovine knee joints. To determine weather non-anatomical fracture reduction with lateral gap or vertical step condition leads to relevant changes in DE in the human knee joint, we tested the applicability of the new method on human LTSFs and investigated whether the current limit of 2 mm gap and step is durable from a biomechanical point of view.

Influence of reduction accuracy in lateral tibial plateau fractures on intra-articular friction - a biomechanical study.

Clubfoot is one of the most prevalent musculoskeletal congenital defects. Gold standard treatment of idiopathic clubfoot is the conservative Ponseti method, including the reduction of deformity with weekly serial plaster casting and percutaneous Achilles tenotomy. It is well known that parents of children with severe and chronic illnesses are mentally stressed, but in recent studies regarding clubfoot treatment, parents were only asked about their satisfaction with the treatment. Largely unknown is parental distress before and during plaster casting in clubfoot. Therefore, we want to determinate first, how pronounced the parents' worries are before treatment and if they decrease during the therapy. Second, we hypothesized that parents faced with an extreme deformity (high Pirani score), reveal more distress, than parents whose children have a less pronounced deformity (low Pirani score). Therefore, we wanted to investigate whether the Pirani score correlates with the parents' mental resilience in relation to the therapy of the child as a global distress parameter.

Clubfoot treatment with Ponseti method-parental distress during plaster casting.

Bone is a frequent site of metastases, being typically associated with a short-term prognosis in affected patients. Photodynamic therapy (PDT) emerges as a promising alternative treatment for controlling malignant disease that can directly target interstitial metastatic lesions. The aim of this study was to assess the effect induced by PDT treatment on both primary (giant cell bone tumor) and human bone metastatic cancer cell lines (derived from a primary invasive ductal breast carcinoma and renal carcinoma). After 24 h post light delivery (blue light-wavelength 436 nm) with 5-aminolevulinic acid, the effect on cellular migration, viability, apoptosis, and senescence were assessed. Our results showed that bone metastasis derived from breast cancer reacted with an inhibition of cell migration coupled with reduced viability and signs of apoptosis such as nuclei fragmentation following PDT exposure. A limited effect in terms of cellular viability inhibition was observed for the cells of giant cell bone tumors. In contrast, bone metastasis derived from renal carcinoma followed a different fate-cells were characterized by senescent features, without a notable effect on cell migration or viability. Collectively, our study illustrates that PDT could act as a successful therapy concept for local tumor control in some entities of bone metastases.

ArticleTotal : 2	Year
Publication title	2021
Publication title Cited by 1	2022

Article	Year
Dissipated energy as a method to characterize the cartilage damage in large animal joints: an in vitro testing model. Medical engineering & physics\| PubMed ID: 23375506	2013
Changes in dissipated energy and contact pressure after osteochondral graft transplantation. Medical engineering & physics\| PubMed ID: 25066582	2014
The Effects of Hip and Spine Orthoses on Braking Parameters: A Simulated Study With Healthy Subjects. PM & R : the journal of injury, function, and rehabilitation\| PubMed ID: 26079866	2016
Robot-aided in vitro measurement of patellar stability with consideration to the influence of muscle loading. Biomedical engineering online\| PubMed ID: 26201401	2015
Predictability of the effects of facet joint infiltration in the degenerate lumbar spine when assessing MRI scans. Journal of orthopaedic surgery and research\| PubMed ID: 29162138	2017
Chondrocyte death after mechanically overloading degenerated human intervertebral disk explants is associated with a structurally impaired pericellular matrix. Journal of tissue engineering and regenerative medicine\| PubMed ID: 30053767	2018
Interobserver Reliability When Classifying MR Imaging of the Lumbar Spine: Written Instructions Alone Do Not Suffice. Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine\| PubMed ID: 31548477	2019
Predictability of the effects of epidural injection in lumbar spinal stenosis by assessment of lumbar MRI scans. Journal of back and musculoskeletal rehabilitation\| PubMed ID: 31743983	2019
Influence of reduction accuracy in lateral tibial plateau fractures on intra-articular friction - a biomechanical study. BMC musculoskeletal disorders\| PubMed ID: 31926549	2020
Clubfoot treatment with Ponseti method-parental distress during plaster casting. Journal of orthopaedic surgery and research\| PubMed ID: 32680553	2020
Assessment of 5-Aminolevulinic Acid-Mediated Photodynamic Therapy on Bone Metastases: An in Vitro Study. Biology\| PubMed ID: 34681119	2021

Christian Walter

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