Biomechanical analysis of plate systems for proximal humerus fractures: a systematic literature review

Background Proximal humerus fractures are the third most common in the human body but their management remains controversial. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. The development of technologies and techniques for these plates, during the recent decades, promise a bright future for their clinical use. A comprehensive review of in vitro biomechanical studies is needed for the comparison of plates’ mechanical performance and the testing methodologies. This will not only guide clinicians with plate selection but also with the design of future in vitro biomechanical studies. This review was aimed to systematically categorise and review the in vitro biomechanical studies of these plates based on their protocols and discuss their results. The technologies and techniques investigated in these studies were categorised and compared to reach a census where possible. Methods and results Web of Science and Scopus database search yielded 62 studies. Out of these, 51 performed axial loading, torsion, bending and/or combined bending and axial loading while 11 simulated complex glenohumeral movements by using tendons. Loading conditions and set-up, failure criteria and performance parameters, as well as results for each study, were reviewed. Only two studies tested four-part fracture model while the rest investigated two- and three-part fractures. In ten studies, synthetic humeri were tested instead of cadaveric ones. In addition to load–displacement data, three-dimensional motion analysis systems, digital image correlation and acoustic emission testing have been used for measurement. Conclusions Overall, PHILOS was the most tested plate and locking plates demonstrated better mechanical performance than non-locking ones. Conflicting results have been published for their comparison with non-locking blade plates and polyaxial locking screws. Augmentation with cement [calcium phosphate or poly(methyl methacrylate)] or allografts (fibular and femoral head) was found to improve bone-plate constructs’ mechanical performance. Controversy still lies over the use of rigid and semi-rigid implants and the insertion of inferomedial screws for calcar region support. This review will guide the design of in vitro and in silico biomechanical tests and also supplement the study of clinical literature

Rehabilitation following shoulder arthroplasty in the United Kingdom National Health Service: A survey of publicly facing information.

INTRODUCTION:The prevalence of shoulder arthroplasty (SA) is rising, but there is limited research evaluating rehabilitation following SA and whether there is an optimal approach remains unknown. The aim of this study was to understand current National Health Service (NHS) practice for rehabilitation following SA as a platform for conducting much needed further research. METHODS:Two reviewers independently undertook electronic searches for publicly available information sheets (PIS) from websites of NHS Trusts that included detail about rehabilitation following SA, for example, duration of immobilisation. One reviewer extracted data, and a second reviewer verified this. ETHICAL APPROVAL:Not required. RESULTS:Forty-three PIS from 40 Trusts were identified. Twenty-four referred to more than one type of arthroplasty (anatomic, reverse and hemiarthroplasty) but did not describe different approaches to rehabilitation based on prosthesis type. Twenty-five PIS provided some instruction regarding movement restrictions, which varied considerably. All PIS referred to postoperative immobilisation, typically with a sling, with median duration of 4 weeks (range 0 to 8). Thirty-four PIS reported commencing passive exercise immediately. Median time to commencing active exercise was 4 weeks (range 1 to 6) and 5 weeks (range 1 to 16) for resisted exercise. Median time expected to return to driving was 6 weeks (range 3 to 12) and general work 12 weeks (range 3 to 26). CONCLUSION:This study has highlighted significant heterogeneity between rehabilitation approaches following SA, not previously reported in the United Kingdom, with a lack of specific rehabilitation PIS for different prosthesis types. Our results will facilitate evaluation of rehabilitation strategies in future research

Biological perspectives and current biofabrication strategies in osteochondral tissue engineering

From Springer Nature via Jisc Publications RouterHistory: received 2019-09-26, accepted 2020-06-29, registration 2020-06-29, pub-electronic 2020-07-09, online 2020-07-09, pub-print 2020-12Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/L014904/1Funder: Fundação para a Ciência e a Tecnologia; doi: http://dx.doi.org/10.13039/501100001871; Grant(s): PTDC/MEC-GIN/29232/2017, 0245_IBEROS_1_EAbstract: Articular cartilage and the underlying subchondral bone are crucial in human movement and when damaged through disease or trauma impacts severely on quality of life. Cartilage has a limited regenerative capacity due to its avascular composition and current therapeutic interventions have limited efficacy. With a rapidly ageing population globally, the numbers of patients requiring therapy for osteochondral disorders is rising, leading to increasing pressures on healthcare systems. Research into novel therapies using tissue engineering has become a priority. However, rational design of biomimetic and clinically effective tissue constructs requires basic understanding of osteochondral biological composition, structure, and mechanical properties. Furthermore, consideration of material design, scaffold architecture, and biofabrication strategies, is needed to assist in the development of tissue engineering therapies enabling successful translation into the clinical arena. This review provides a starting point for any researcher investigating tissue engineering for osteochondral applications. An overview of biological properties of osteochondral tissue, current clinical practices, the role of tissue engineering and biofabrication, and key challenges associated with new treatments is provided. Developing precisely engineered tissue constructs with mechanical and phenotypic stability is the goal. Future work should focus on multi-stimulatory environments, long-term studies to determine phenotypic alterations and tissue formation, and the development of novel bioreactor systems that can more accurately resemble the in vivo environment

Mechanical, biological and tribological behaviour of fixation plates 3D printed by electron beam and selective laser melting

From Springer Nature via Jisc Publications RouterHistory: received 2019-10-30, accepted 2020-06-22, registration 2020-06-22, pub-print 2020-07, pub-electronic 2020-07-06, online 2020-07-06Publication status: PublishedFunder: University of ManchesterAbstract: Commercially available fixation plates are built using metallic biocompatible materials such as titanium and its alloys and stainless steel. However, these plates show a stiffness mismatch comparing to bone, leading to stress shielding and bone loss. In this paper, we investigate the combined use of topology optimisation and additive manufacturing to print fixation plates with reduced stiffness and improved biological performance. Ti-6Al-4 V plates were topology optimised considering different loading conditions and volume reductions and printed using electron beam melting and selective laser melting. The effect of processing conditions on the mechanical properties, microhardness, wear resistance and surface roughness was analysed. Results show acceptable wear resistance values for a medical device and a reduction of stress shielding by increasing volume reduction. It is also shown that no polishing is required as 3D printed plates are able to support cell attachment and proliferation. In comparison to commercial plates, 3D printed ones show significantly better biological performance. For the same design, SLM plates present higher mechanical properties, while EBM plates present better cell attachment and proliferation

Can hedgerow management mitigate the impacts of predation on songbird nest survival?

Nest predators can have significant impacts on songbird reproductive success. These impacts may be amplified by habitat simplification and here we test whether sympathetic management of farmland hedgerows can reduce nest depredation, especially by corvids. We test whether songbirds select nest sites according to structural features of hedgerows (including nest visibility and accessibility), and whether these features influence nest predation risk. Songbirds selected nesting sites affording higher vegetation cover above the nest, increased visibility on the nest-side of the hedgerow and reduced visibility on the far side of the hedge. Nest survival was unrelated to corvid abundance and only weakly related (at the egg stage) to corvid nest proximity. Nest survival at the chick stage was higher where vegetation structure restricted access to corvid-sized predators (averaging 0.78 vs. 0.53), and at nests close to potential vantage points. Overall nest survival was sensitive to hedgerow structure (accessibility) particularly at low exposure to corvid predation, while the overall impact of corvid exposure was dependent on the relationship involving proximity to vantage points. Nest survival over the chick stage was much higher (0.67) in stock-proof, trimmed and mechanically cut hedgerows, (which tended to provide lower side visibility and accessibility) than in recently laid, remnant or leggy hedgerows (0.18). Long-term reductions in the management of British hedgerows may therefore be exposing nesting songbirds to increased predation risk. We recommend regular rotational cutting of hedgerows to maintain a dense woody structure and thereby reduce songbird nest predation

Biomechanical comparison of screw-based zoning of PHILOS and Fx proximal humerus plates

Background Treatment of proximal humerus fractures with locking plates is associated with complications. We aimed to compare the biomechanical effects of removing screws and blade of a fixed angle locking plate and hybrid blade plate, on a two-part fracture model. Methods Forty-five synthetic humeri were divided into nine groups where four were implanted with a hybrid blade plate and the remaining with locking plate, to treat a two-part surgical neck fracture. Plates’ head screws and blades were divided into zones based on their distance from fracture site. Two groups acted as a control for each plate and the remaining seven had either a vacant zone or blade swapped with screws. For elastic cantilever bending, humeral head was fixed and the shaft was displaced 5 mm in extension, flexion, valgus and varus direction. Specimens were further loaded in varus direction to investigate their plastic behaviour. Results In both plates, removal of inferomedial screws or blade led to a significantly larger drop in varus construct stiffness than other zones. In blade plate, insertion of screws in place of blade significantly increased the mean extension, flexion valgus and varus bending stiffness (24.458%/16.623%/19.493%/14.137%). In locking plate, removal of screw zones proximal to the inferomedial screws reduced extension and flexion bending stiffness by 26–33%. Conclusions Although medial support improved varus stability, two inferomedial screws were more effective than blade. Proximal screws are important for extension and flexion. Mechanical consequences of screw removal should be considered when deciding the number and choice of screws and blade in clinic

Parametric design optimisation of proximal humerus plates based on finite element method

Optimal treatment of proximal humerus fractures remains controversial. Locking plates offer theoretical advantages but are associated with complications in the clinic. This study aimed to perform parametric design optimisation of proximal humerus plates to enhance their mechanical performance. A finite element (FE) model was developed that simulated a two-part proximal humerus fracture that had been treated with a Spatial Subchondral Support (S3) plate and subjected to varus bending. The FE model was validated against in vitro biomechanical test results. The predicted load required to apply 5 mm cantilever varus bending was only 0.728% lower. The FE model was then used to conduct a parametric optimisation study to determine the orientations of inferomedial plate screws that would yield minimum fracture gap change (i.e. optimal stability). The feasible design space was automatically identified by imposing clinically relevant constraints, and the creation process of each FE model for the design optimisation was automated. Consequently, 538 FE models were generated, from which the obtained optimal model had 4.686% lower fracture gap change (0.156 mm) than that of the manufacturer’s standard plate. Whereas its screws were oriented towards the inferomedial region and within the range of neck-shaft angle of a healthy subject. The methodology presented in this study promises future applications in patient-specific design optimisation of implants for other regions of the human body

The genome of the green anole lizard and a comparative analysis with birds and mammals

The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments. Among amniotes, genome sequences are available for mammals and birds, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes. Also, A. carolinensis mobile elements are very young and diverse—more so than in any other sequenced amniote genome. The GC content of this lizard genome is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations.National Science Foundation (U.S.) (NSF grant DEB-0920892)National Science Foundation (U.S.) (NSF grant DEB-0844624)National Human Genome Research Institute (U.S.

Subduction or sagduction? Ambiguity in constraining the origin of ultramafic–mafic bodies in the Archean crust of NW Scotland

The Lewisian Complex of NW Scotland is a fragment of the North Atlantic Craton. It comprises mostly Archean tonalite–trondhjemite–granodiorite (TTG) orthogneisses that were variably metamorphosed and reworked in the late Neoarchean to Paleoproterozoic. Within the granulite facies central region of the mainland Lewisian Complex, discontinuous belts composed of ultramafic–mafic rocks and structurally overlying garnet–biotite gneiss (brown gneiss) are spatially associated with steeply-inclined amphibolite facies shear zones that have been interpreted as terrane boundaries. Interpretation of the primary chemical composition of these rocks is complicated by partial melting and melt loss during granulite facies metamorphism, and contamination with melts derived from the adjacent migmatitic TTG host rocks. Notwithstanding, the composition of the layered ultramafic–mafic rocks is suggestive of a protolith formed by differentiation of tholeiitic magma, where the ultramafic portions of these bodies represent the metamorphosed cumulates and the mafic portions the metamorphosed fractionated liquids. Although the composition of the brown gneiss does not clearly discriminate the protolith, it most likely represents a metamorphosed sedimentary or volcano-sedimentary sequence. For Archean rocks, particularly those metamorphosed to granulite facies, the geochemical characteristics typically used for discrimination of paleotectonic environments are neither strictly appropriate nor clearly diagnostic. Many of the rocks in the Lewisian Complex have ‘arc-like’ trace element signatures. These signatures are interpreted to reflect derivation from hydrated enriched mantle and, in the case of the TTG gneisses, partial melting of amphibolite source rocks containing garnet and a Ti-rich phase, probably rutile. However, it is becoming increasingly recognised that in Archean rocks such signatures may not be unique to a subduction environment but may relate to processes such as delamination and dripping. Consequently, it is unclear whether the Lewisian ultramafic–mafic rocks and brown gneisses represent products of plate margin or intraplate magmatism. Although a subduction-related origin is possible, we propose that an intraplate origin is equally plausible. If the second alternative is correct, the ultramafic–mafic rocks and brown gneisses may represent the remnants of intracratonic greenstone belts that sank into the deep crust due to their density contrast with the underlying partially molten low viscosity TTG orthogneisses

Effect of a Perioperative, Cardiac Output-Guided Hemodynamic Therapy Algorithm on Outcomes Following Major Gastrointestinal Surgery A Randomized Clinical Trial and Systematic Review

Importance: small trials suggest that postoperative outcomes may be improved by the use of cardiac output monitoring to guide administration of intravenous fluid and inotropic drugs as part of a hemodynamic therapy algorithm.Objective: to evaluate the clinical effectiveness of a perioperative, cardiac output–guided hemodynamic therapy algorithm.Design, setting, and participants: OPTIMISE was a pragmatic, multicenter, randomized, observer-blinded trial of 734 high-risk patients aged 50 years or older undergoing major gastrointestinal surgery at 17 acute care hospitals in the United Kingdom. An updated systematic review and meta-analysis were also conducted including randomized trials published from 1966 to February 2014.Interventions: patients were randomly assigned to a cardiac output–guided hemodynamic therapy algorithm for intravenous fluid and inotrope (dopexamine) infusion during and 6 hours following surgery (n=368) or to usual care (n=366).Main outcomes and measures: the primary outcome was a composite of predefined 30-day moderate or major complications and mortality. Secondary outcomes were morbidity on day 7; infection, critical care–free days, and all-cause mortality at 30 days; all-cause mortality at 180 days; and length of hospital stay.Results: baseline patient characteristics, clinical care, and volumes of intravenous fluid were similar between groups. Care was nonadherent to the allocated treatment for less than 10% of patients in each group. The primary outcome occurred in 36.6% of intervention and 43.4% of usual care participants (relative risk [RR], 0.84 [95% CI, 0.71-1.01]; absolute risk reduction, 6.8% [95% CI, ?0.3% to 13.9%]; P?=?.07). There was no significant difference between groups for any secondary outcomes. Five intervention patients (1.4%) experienced cardiovascular serious adverse events within 24 hours compared with none in the usual care group. Findings of the meta-analysis of 38 trials, including data from this study, suggest that the intervention is associated with fewer complications (intervention, 488/1548 [31.5%] vs control, 614/1476 [41.6%]; RR, 0.77 [95% CI, 0.71-0.83]) and a nonsignificant reduction in hospital, 28-day, or 30-day mortality (intervention, 159/3215 deaths [4.9%] vs control, 206/3160 deaths [6.5%]; RR, 0.82 [95% CI, 0.67-1.01]) and mortality at longest follow-up (intervention, 267/3215 deaths [8.3%] vs control, 327/3160 deaths [10.3%]; RR, 0.86 [95% CI, 0.74-1.00]).Conclusions and relevance: in a randomized trial of high-risk patients undergoing major gastrointestinal surgery, use of a cardiac output–guided hemodynamic therapy algorithm compared with usual care did not reduce a composite outcome of complications and 30-day mortality. However, inclusion of these data in an updated meta-analysis indicates that the intervention was associated with a reduction in complication rate