Crepuscular rays - The bright side of complement after tissue injury.

Acute injuries trigger an intense activation of the body's defense mechanisms aiming to limit damage and initiate healing. Among the crucial components of the intravascular immune system, the complement system plays a significant role in traumatic injuries, albeit often negatively. It has been suggested that excessive activation of the complement system, transitioning from a localized and timed response to a systemic one, can lead to a loss of its host-protective characteristics.

Automatic grading of intervertebral disc degeneration in lumbar dog spines.

Background: Intervertebral disc degeneration is frequent in dogs and can be associated with symptoms and functional impairments. The degree of disc degeneration can be assessed on T2-weighted MRI scans using the Pfirrmann classification scheme, which was developed for the human spine. However, it could also be used to quantify the effectiveness of disc regeneration therapies.

Improving bone defect healing using magnesium phosphate granules with tailored degradation characteristics.

Objectives: Dental implant placement frequently requires preceding bone augmentation, for example, with hydroxyapatite (HA) or β-tricalcium phosphate (β-TCP) granules. However, HA is degraded very slowly in vivo and for β-TCP inconsistent degradation profiles from too rapid to rather slow are reported. To shorten the healing time before implant placement, rapidly resorbing synthetic materials are of great interest.

Accelerated bone regeneration through rational design of magnesium phosphate cements.

Results of several studies during past years suggested that magnesium phosphate cements (MPCs) not only show excellent biocompatibility and osteoconductivity, but they also provide improved regeneration capacity due to higher solubility compared to calcium phosphates. These findings also highlighted that chemical similarity of bone substitutes to the natural bone tissue is not a determinant factor in the success of regenerative strategies. The aim of this study was to further improve the degradation speed of MPCs for a fast bone ingrowth within a few months.

Improvement of clinical fracture healing - What can be learned from mechano-biological research?

The most significant predictors of reoperation following operative management of fractures are the presence of a third degree open fracture, remaining fracture gaps and a transverse fracture. However clinical studies provide no information regarding the involvement of various soft tissues or how the mechanical environment affects revascularisation and bone healing. Here the results of experimental and numerical mechano-biological studies on fracture healing are summarized to provide guidance toward clinical treatment of fractures.

A Deep Learning Model for the Accurate and Reliable Classification of Disc Degeneration Based on MRI Data.

Objectives: Although magnetic resonance imaging-based formalized grading schemes for intervertebral disc degeneration offer improved reproducibility compared with purely subjective ratings, their intrarater and interrater reliability are not nearly good enough to be able to detect small to medium effects in clinical longitudinal studies. The aim of this study thus was to develop a method that enables automatic and therefore reproducible and reliable evaluation of disc degeneration based on conventional clinical image data and Pfirrmann's grading scheme.

Materials And Methods: We propose a classifier based on a deep convolutional neural network that we trained on a large, manually evaluated data set of 1599 patients (7948 intervertebral discs).

Simulating lateral distraction osteogenesis.

Distraction osteogenesis is an effective method for generating large amounts of bone in situ for treating pathologies such as large bone defects or skeletal malformations, for instance leg-length discrepancies. While an optimized distraction procedure might have the potential to reduce the rate of complications significantly, our knowledge of the underlying mechanobiological processes is still insufficient for systematic optimization of treatment parameters such as distraction rate or fixation stiffness. We present a novel numerical model of lateral distraction osteogenesis, based on a mechanically well-controlled in vivo experiment.

Bone regeneration capacity of magnesium phosphate cements in a large animal model.

Unlabelled: Magnesium phosphate minerals have captured increasing attention during the past years as suitable alternatives for calcium phosphate bone replacement materials. Here, we investigated the degradation and bone regeneration capacity of experimental struvite (MgNHPO·6HO) forming magnesium phosphate cements in two different orthotopic ovine implantation models. Cements formed at powder to liquid ratios (PLR) of 2.

Phytic acid as alternative setting retarder enhanced biological performance of dicalcium phosphate cement in vitro.

Dicalcium phosphate cement preparation requires the addition of setting retarders to meet clinical requirements regarding handling time and processability. Previous studies have focused on the influence of different setting modifiers on material properties such as mechanical performance or injectability, while ignoring their influence on biological cement properties as they are used in low concentrations in the cement pastes and the occurrence of most compounds in human tissues. Here, analyses of both material and biological behavior were carried out on samples with common setting retardants (citric acid, sodium pyrophosphate, sulfuric acid) and novel (phytic acid).

Mg:Ca ratio as regulating factor for osteoclastic in vitro resorption of struvite biocements.

Bioceramic degradation can occur by both passive dissolution and following active osteoclastic bone remodeling. Key parameters controlling ceramic degradation are the pH-dependent solubility product of the ceramic phase, which alters ion concentrations in physiological solution and hence regulates cell activity. This study investigated the in vitro degradation profiles of various calcium magnesium phosphate ceramics formed at low temperature.

Control of in vivo mineral bone cement degradation.

The current study aimed to prevent the formation of hydroxyapatite reprecipitates in brushite-forming biocements by minimizing the availability of free Ca(2+) ions in the cement matrix. This was achieved by both maximizing the degree of cement setting to avoid unreacted, calcium-rich cement raw materials which can deliver Ca(2+) directly to the cement matrix after dissolution, and by a reduction in porosity to reduce Ca(2+) diffusion into the set cement matrix. In addition, a biocement based on the formation of the magnesium phosphate mineral struvite (MgNH4PO4·6H2O) was tested, which should prevent the formation of low-solubility hydroxyapatite reprecipitates due to the high magnesium content.

Internal morphology of human facet joints: comparing cervical and lumbar spine with regard to age, gender and the vertebral core.

Back pain constitutes a major problem in modern societies. Facet joints are increasingly recognised as a source of such pain. Knowledge about the internal morphology and its changes with age may make it possible to include the facets more in therapeutic strategies, for instance joint replacements or immobilisation.

Damage accumulation in vertebral trabecular bone depends on loading mode and direction.

Osteoporotic vertebral fractures constitute a major clinical problem in ageing societies. A third of all vertebral fractures is caused by falls, 15% by lifting heavy loads or traffic accidents and over 50% are not relatable to a traumatic event. In the latter case vertebrae show sinter processes which indicate the accumulation of damage and permanent deformation.

Rehydration of vertebral trabecular bone: influences on its anisotropy, its stiffness and the indentation work with a view to age, gender and vertebral level.

For understanding the fracture risk of vertebral bodies the macroscopic mechanical properties of the cancellous core are of major interest. Due to the hierarchical nature of bone, these depend in turn on the micromechanical properties of bone extracellular matrix which is at least linear elastic transverse isotropic. The experimental determination of local elastic properties of bone ex vivo necessitates a high spatial resolution which can be provided by depth-sensing indentation techniques.

Can a modified interspinous spacer prevent instability in axial rotation and lateral bending? A biomechanical in vitro study resulting in a new idea.

Background: Interspinous spacers are mainly used to treat lumbar spinal stenosis and facet arthrosis. Biomechanically, they stabilise in extension but do not compensate instability in axial rotation and lateral bending. It would therefore be desirable to have an interspinous spacer available, which provides for more stability also in these two planes.

Are the spines of calf, pig and sheep suitable models for pre-clinical implant tests?

Pre-clinical in vitro tests are needed to evaluate the biomechanical performance of new spinal implants. For such experiments large animal models are frequently used. Whether these models allow any conclusions concerning the implant's performance in humans is difficult to answer.

Morphological changes of cervical facet joints in elderly individuals.

To better understand the role of facet joint degeneration in chronic neck and back pain epidemiological and morphological data are needed. For the cervical spine, however, such data are rare. Therefore, the aim of this study was to determine the degree of cartilage degeneration of cervical facet joints with respect to spinal level and age, to investigate whether any region of the joint surface is more often affected by degeneration and to determine the localisation of osteophytes.

Biomechanical behavior of a new nucleus prosthesis made of knitted titanium filaments.

Background: One of the greatest challenges in the development of a nucleus prosthesis is to minimize the risk of implant expulsion. At the same time, the physiological flexibility, compressive behavior, and height of the disc should be restored. In this biomechanical in vitro study we investigated the ability of a new nucleus prosthesis made of knitted titanium filaments to meet these challenges.

The enhancement of bone regeneration by ultrasound.

Millions of fractures occur every year worldwide, with nearly 6.2 million fractures reported annually in the United States alone. Even though treatment methods have improved over the last few decades, 5-10% of fractures still show delayed healing.

Moderate soft tissue trauma delays new bone formation only in the early phase of fracture healing.

The aim of this study was to investigate the effect of a moderate soft tissue trauma to the course of fracture healing in a standardized animal model. Thirty-eight Wistar rats were randomly divided into a fracture group (F, n = 19) and a group with a fracture and a soft tissue trauma (F + STT, n = 19). The fracture and the soft tissue trauma were created using an impact device with a standardized energy.

Biomechanical performance of the new BeadEx implant in the treatment of osteoporotic vertebral body compression fractures: restoration and maintenance of height and stability.

Background: Vertebral compression fractures are counted among the most common complications of osteoporosis. For treatment, a new, alternative implant has been developed (BeadEx, Expandis, Hof HaCarmel, Israel). The aim of the present in vitro study was to evaluate whether this implant is able to restore the initial height and three-dimensional stability after fracture and whether it is able to maintain this height and stability during complex cyclic loading.

In vitro fixator rod loading after transforaminal compared to anterior lumbar interbody fusion.

Background: Cages are commonly used to assist lumbar interbody fusion. They are implanted from various approaches. In many cases internal fixators are added to provide sufficient stability.

Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure.

In recent years, non-fusion implants to stabilise the lumbar spine have become more and more popular. However, little is known on the load bearing of such dynamic stabilisation systems. In order to investigate the load bearing of discs bridged with rigid and dynamic stabilisation systems, six lumbar cadaver spines were mounted in a spine tester and loaded with pure moments in the three main motion planes.

Validity and interobserver agreement of a new radiographic grading system for intervertebral disc degeneration: Part I. Lumbar spine.

Many different radiographic grading systems for disc degeneration are described in literature. However, only a few of them are tested for interobserver agreement and none for validity. Furthermore, most of them are based on a subjective terminology.