Histomorphometric Assessment of Cancellous and Cortical Bone Material Distribution in the Proximal Humerus of Normal and Osteoporotic Individuals Significantly Reduced Bone Stock in the Metaphyseal and Subcapital Regions of Osteoporotic Individuals

Osteoporosis is a systemic disorder predominantly affecting postmenopausal women but also men at an advanced age. Both genders may suffer from low-energy fractures of, for example, the proximal humerus when reduction of the bone stock or/and quality has occurred. The aim of the current study was to compare the amount of bone in typical fracture zones of the proximal humerus in osteoporotic and non-osteoporotic individuals. The amount of bone in the proximal humerus was determined histomorphometrically in frontal plane sections. The donor bones were allocated to normal and osteoporotic groups using the T-score from distal radius DXA measurements of the same extremities. The T-score evaluation was done according to WHO criteria. Regional thickness of the subchondral plate and the metaphyseal cortical bone were measured using interactive image analysis. At all measured locations the amount of cancellous bone was significantly lower in individuals from the osteoporotic group compared to the non-osteoporotic one. The osteoporotic group showed more significant differences between regions of the same bone than the non-osteoporotic group. In both groups the subchondral cancellous bone and the subchondral plate were least affected by bone loss. In contrast, the medial metaphyseal region in the osteoporotic group exhibited higher bone loss in comparison to the lateral side. This observation may explain prevailing fracture patterns, which frequently involve compression fractures and certainly has an influence on the stability of implants placed in this medial region. It should be considered when planning the anchoring of osteosynthesis materials in osteoporotic patients with fractures of the proximal humerus

Radial Shock Wave Devices Generate Cavitation

Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. Methods and Findings We used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast;Electro Medical Systems, Nyon, Switzerland;D-Actor 200;Storz Medical, Tagerwillen, Switzerland) and a vibrating massage device (Vibracare;G5/General Physiotherapy, Inc.,Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms. Results FOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device. Conclusions The results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices

Age and gender as determinants of the bone quality of the greater tuberosity: A HR-pQCT cadaver study

Background: Age-dependent trabecular changes of the humeral head might weaken the fixation of suture anchors used for rotator cuff (RC) repair. This might lead to suture anchor loosening and thus compromise the integrity of the repair. The aim of this study was to analyze whether the trabecular microstructure within the RC footprint is influenced by age, gender or handedness. Methods: Axial HR-pQCT scans (Scanco Medical) of 64 freshly frozen cadaveric human humeral head specimens (age 72.3 +/- 17.4 years) were analyzed to determine the bone volume-to-total volume ratio (BV/TV), trabecular thickness (Trab Th), trabecular number (Trab N) and connectivity density (Conn Dens). Within the RC footprint, 2 volumes of interest (VOI), posteromedial (PM) and anterolateral (AL) and one control VOI in the subarticular bone (SC) were set. Results: The highest BV/TV was found in SC: 0.22 +/- 0.06% vs. PM: 0.04 +/- 0.05% vs. AL: 0.02 +/- 0.04%; p < 0.05. Trab Th accounted for 0.26 +/- 0.05 mu m in SC, 0.23 +/- 0.09 mu m in AL and 0.21 +/- 0.05 mu m in PM. In parallel, Trab N and Conn Dens were found to be the highest in SC. Gender analysis yielded higher values for BV/TV, Trab Th, Trab N and Conn Dens for PM in males compared to females (p < 0.05). There were no significant findings when comparing both sides. We furthermore found a strong inverse correlation between age and BV/TV, which was more pronounced in the female specimens (r = -0.72, p < 0.00001). Conclusions: The presented microarchitectural data allow for future subtle biomechanical testing comprising knowledge on age-and sex-related changes of the tuberosities of the humeral head. Furthermore, the insights on the trabecular structure of the humeral head of the elderly may lead to the development of new fixation materials in bone with inferior bone quality

Orbital floor repair using patient specific osteoinductive implant made by stereolithography

The orbital floor (OF) is an anatomical location in the craniomaxillofacial (CMF) region known to be highly variable in shape and size. When fractured, implants commonly consisting of titanium meshes are customized by plying and crude hand-shaping. Nevertheless, more precise customized synthetic grafts are needed to meticulously reconstruct the patients’ OF anatomy with better fidelity. As alternative to titanium mesh implants dedicated to OF repair, we propose a flexible patient-specific implant (PSI) made by stereolithography (SLA), offering a high degree of control over its geometry and architecture. The PSI is made of biodegradable poly(trimethylene carbonate) (PTMC) loaded with 40 wt % of hydroxyapatite (called Osteo-PTMC). In this work, we developed a complete work-flow for the additive manufacturing of PSIs to be used to repair the fractured OF, which is clinically relevant for individualized medicine. This work-flow consists of (i) the surgical planning, (ii) the design of virtual PSIs and (iii) their fabrication by SLA, (iv) the monitoring and (v) the biological evaluation in a preclinical large-animal model. We have found that once implanted, titanium meshes resulted in fibrous tissue encapsulation, whereas Osteo-PMTC resulted in rapid neovascularization and bone morphogenesis, both ectopically and in the OF region, and without the need of additional biotherapeutics such as bone morphogenic proteins. Our study supports the hypothesis that the composite osteoinductive Osteo-PTMC brings advantages compared to standard titanium mesh, by stimulating bone neoformation in the OF defects. PSIs made of Osteo-PTMC represent a significant advancement for patients whereby the anatomical characteristics of the OF defect restrict the utilization of traditional hand-shaped titanium mesh

Outcome analysis following removal of locking plate fixation of the proximal humerus

<p>Abstract</p> <p>Background</p> <p>Concerning surgical management experience with locking plates for proximal humeral fractures has been described with promising results. Though, distinct hardware related complaints after fracture union are reported. Information concerning the outcome after removal of hardware from the proximal humerus is lacking and most studies on hardware removal are focused on the lower extremity. Therefore the aim of this study was to analyze the functional short-term outcome following removal of locking plate fixation of the proximal humerus.</p> <p>Methods</p> <p>Patients undergoing removal of a locking plate of the proximal humerus were prospectively followed. Patients were subdivided into the following groups: Group HI: symptoms of hardware related subacromial impingement, Group RD: persisting rotation deficit, Group RQ: patients with request for a hardware removal. The clinical (Constant-Murley score) and radiologic (AP and axial view) follow-up took place three and six months after the operation. To evaluate subjective results, the Medical Outcomes Study Short Form-36 (SF-36), was completed.</p> <p>Results</p> <p>59 patients were included. The mean length of time with the hardware in place was 15.2 ± 3.81 months. The mean of the adjusted overall Constant score before hardware removal was 66.2 ± 25.2% and increased significantly to 73.1 ± 22.5% after 3 months; and to 84.3 ± 20.6% after 6 months (p < 0.001). The mean of preoperative pain on the VAS-scale before hardware removal was 5.2 ± 2.9, after 6 months pain in all groups decreased significantly (p < 0.001). The SF-36 physical component score revealed a significant overall improvement in both genders (p < 0.001) at six months.</p> <p>Conclusion</p> <p>A significant improvement of clinical outcome following removal was found. However, a general recommendation for hardware removal is not justified, as the risk of an anew surgical and anesthetic procedure with all possible complications has to be carefully taken into account. However, for patients with distinct symptoms it might be justified.</p

Influence of head size on the development of metallic wear and on the characteristics of carbon layers in metal-on-metal hip joints

Background and purpose Particles originating from the articulating surfaces of hip endoprostheses often induce an inflammatory response, which can be related to implant failure. We therefore analyzed the metal content in capsular tissue from 44 McKee-Farrar metal-on-metal hip prostheses (with 3 different head sizes) and we also analyzed the morphological structure of layers located on articulating surfaces

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Influencing biophysical properties of fibrin with buffer solutions

Fibrin has been proposed as cell scaffold for numerous tissue engineering applications. While most of the studies have focused on fibrinogen and thrombin, other components of fibrin can also affect its properties. The present study aimed to evaluate the effects of buffer solu- tion composition on fibrin biophysical properties. Fibrin scaffolds were synthesized with different calcium, chlo- ride, and factor XIII (FXIII) final concentrations. Light transmission was determined as a relative, semi-quantita- tive estimator of fiber structure differences, and two com- positions, resulting in translucent and opaque gels, were tested for mechanical and biological properties. Gels were seeded with mouse mesenchymal cells, C3H10T1/2, or bovine bone marrow-derived mesenchymal stromal cells and cultured up to 10 or 24 days, before cell number, morphology and distribution were evaluated. Calcium increased gel opacity (i.e., fiber thickness), while chloride and FXIII decreased it. Opaque gels displayed a fluid-like viscous behavior while translucent gels showed improved elastic properties. Both compositions supported survival of both cell types with opaque gels leading to better prolif- eration, but significant scaffold shrinkage after 17 days of culture. These results demonstrated that calcium, chloride, and FXIII modulate the biophysical properties of fibrin, and can be used to adjust mechanical and biological properties for tissue engineering applicationsPeer ReviewedPostprint (published version