IntroductionDespite successful fusion rates with iliac crest bone graft (ICBG), donor-site morbidity and increased operating time remain a considerable limitation and drive the search for alternatives. In this systematic review, grafts with additional cellular supplementation were compared with ICBG for spinal arthrodesis. We compared safety, efficacy and long-term outcomes, thus providing the current and relevant evidence for orthopaedic surgeons to make informed choices regarding this rapidly developing field.MethodsAn electronic literature search was conducted according to the PRISMA guidelines by two independent reviewers for articles published up to 1st March 2023 using PubMed, EMBASE and the Cochrane Central Register of Controlled Trial. Cellular allografts were not included. The following data were extracted: Number of patients, type of graft, fusion assessment method, follow-up duration, fusion rates, clinical outcomes and complications. The methodological quality of evidence (MQOE) was assessed using the Risk of Bias 2 (RoB-2) tool and Risk of Bias In Non-Randomised Studies (ROBINS) tool developed by Cochrane for evaluating bias in randomised and non-randomised studies.ResultsTen studies fulfiled the inclusion criteria, including 465 patients. The mean number of patients per study was 43.8 (std dev. 28.81, range 12-100). Two studies demonstrated cell-based therapy to be significantly more successful in terms of fusion rates compared to ICBG. However, the remaining eight demonstrated equivocal results. No study found that cell-based therapy was inferior. No difference was seen between the two groups in three studies who focused on degenerative cohorts. No difference in functional outcome scores was seen between the groups. A number of different preparation techniques for cell-based grafts were used throughout the studies.ConclusionCell-based therapy offers a promising alternative to ICBG in spinal fusion surgery, which could help reduce the associated morbidity to patients. This review found that cell-based therapy is non-inferior to iliac crest bone graft and may offer patients an alternative treatment option with fewer complications and reduced post-operative pain. However, the literature to date is limited by heterogeneity of the cell preparation and grafting process. Future research with a unified approach to the cell preparation process is required to fully delineate the potential advantages of this technology.

The complex depth-dependent structure of articular cartilage (AC), consisting of an arcade-like collagen fibre network, enables it to withstand and distribute challenging biomechanical loads. While some clinical advances in cartilage repair have occurred, osteochondral (OC) defect repair remains a significant challenge, with current scaffold-based approaches failing to recapitulate the complex, hierarchical structure of native AC and its interface with the underlying subchondral bone. To address this need, we fabricated bilayered extracellular matrix (ECM)-derived scaffolds with aligned pore architectures by controlled freeze-drying of solubilized AC and bone. By modifying the freeze-drying kinetics and controlling the direction of heat transfer during the freezing step, it was possible to produce anisotropic scaffolds with larger pores which supported homogenous cellular infiltration and greater levels of sulfated glycosaminoglycan (sGAG) deposition. Neo-tissue organization in vitro could also be controlled by altering scaffold pore architecture, with collagen fibres aligning parallel to the long-axis of the pores within scaffolds containing aligned pore networks. Furthermore, we used established in vitro and in vivo assays to demonstrate that AC and bone ECM derived scaffolds could preferentially direct the differentiation of mesenchymal stromal cells (MSCs) towards either a chondrogenic or osteogenic lineage respectively, enabling the development of bilayered ECM scaffolds capable of spatially supporting unique tissue phenotypes. Finally, we implanted these scaffolds into a clinically relevant, large animal model of OC defect repair. After 6 months in vivo, biphasic scaffold implantation was found to improve cartilage matrix deposition, with collagen fibres preferentially aligning parallel to the long axis of the scaffold pores, resulting in a repair tissue that structurally and compositionally was more hyaline-like in nature. These results demonstrate how scaffold architecture and composition can be spatially modulated to direct the regeneration of complex interfaces such as the osteochondral unit, enabling their use as cell-free, off-the-shelf implants for joint regeneration.

Purpose The aim of this study is to identify risk factors associated with postoperative DJF in long constructs for ASD. Methods A retrospective review was performed at a tertiary referral spine centre from 01/01/2007 to 31/12/2016. Demographic, clinical and radiographic parameters were collated for patients with DJF in the postoperative period and compared to those without DJF. Survival analyses were performed using univariate logistic regression to identify variables with a p value < 0.05 for inclusion in multivariate analysis. Spearman’s correlations were performed where applicable. Results One hundred two patients were identified. 41 (40.2%) suffered DJF in the postoperative period, with rod fracture being the most common sign of DJF (13/65; 20.0%). Mean time to failure was 32.4 months. On univariate analysis, pedicle subtraction osteotomy ( p = 0.03), transforaminal lumbar interbody fusion ( p < 0.001), pre-op LL ( p < 0.01), pre-op SVA ( p < 0.01), pre-op SS ( p = 0.02), postop LL ( p = 0.03), postop SVA ( p = 0.01), postop PI/LL ( p < 0.001), LL correction ( p < 0.001), SVA correction ( p < 0.001), PT correction ( p = 0.03), PI/LL correction ( p < 0.001), SS correction ( p = 0.03) all proved significant. On multivariate analysis, pedicle subtraction osteotomy (OR 27.3; p = 0.03), postop SVA ( p < 0.01) and LL correction ( p = 0.02) remained statistically significant as independent risk factors for DJF. Conclusion Recently, DJF has received recognition as its own entity due to a notable postoperative incidence. Few studies to date have evaluated risk factors for DJF. The results of our study highlight that pedicle subtraction osteotomy, poor correction of lumbar lordosis, and sagittal vertical axis are significantly associated with postoperative occurrence of DJF.

Emerging 3D printing technologies can provide exquisite control over the external shape and internal architecture of scaffolds and tissue engineering (TE) constructs, enabling systematic studies to explore how geometric design features influence the regenerative process. Here we used fused deposition modelling (FDM) and melt electrowriting (MEW) to investigate how scaffold microarchitecture influences the healing of large bone defects. FDM was used to fabricate scaffolds with relatively large fibre diameters and low porosities, while MEW was used to fabricate scaffolds with smaller fibre diameters and higher porosities, with both scaffolds being designed to have comparable surface areas. Scaffold microarchitecture significantly influenced the healing response following implantation into critically sized femoral defects in rats, with the FDM scaffolds supporting the formation of larger bone spicules through its pores, while the MEW scaffolds supported the formation of a more round bone front during healing. After 12 weeks in vivo , both MEW and FDM scaffolds supported significantly higher levels of defect vascularisation compared to empty controls, while the MEW scaffolds supported higher levels of new bone formation. Somewhat surprisingly, this superior healing in the MEW group did not correlate with higher levels of angiogenesis, with the FDM scaffold supporting greater total vessel formation and the formation of larger vessels, while the MEW scaffold promoted the formation of a dense microvasculature with minimal evidence of larger vessels infiltrating the defect region. To conclude, the small fibre diameter, high porosity and high specific surface area of the MEW scaffold proved beneficial for osteogenesis and bone regeneration, demonstrating that changes in scaffold architecture enabled by this additive manufacturing technique can dramatically modulate angiogenesis and tissue regeneration without the need for complex exogenous growth factors. These results provide a valuable insight into the importance of 3D printed scaffold architecture when developing new bone TE strategies.

Frailty is a common geriatric syndrome, the relevance of which is becoming increasingly apparent in the clinical setting. It is often accompanied by varying degrees of sarcopenia and/or osteoporosis, leading to a decline in physical function, decreased levels of physical activity, and overall poorer health outcomes in older adults. Identifying this cohort of patients before stressor events such as spinal surgery can prove paramount to improving the postoperative outcomes of these patients. This review provides a pertinent descriptive analysis to aid identification of frailty in a clinical setting, in addition to outlining methods of preoperative intervention that may improve postoperative outcomes.

Objectives:Sarcopenia is postulated to be an influential factor in chronic low back pain. The aim of this study is to evaluate the relationship between traditional clinical measures of sarcopenia and novel radiographic methods which evaluate overall muscle status, such as adjusted psoas cross-sectional area (APCSA) and degree of fat infiltration (%FI) in paraspinal muscles, in patients with chronic low back pain.Methods:Prospective study performed at our institution from 01/01/19-01/04/19. Inclusion criteria were patients ≥65 years old not requiring surgical intervention presenting to a low back pain assessment clinic.Results:25 patients were identified (mean age: 73 years, 62% male). On spearman's analyses, %FI shared a significant relationship with hand grip strength (r = -0.37; p=0.03), chair rise (r=0.38; p=0.03), SC (r=0.64; p<0.01), and visual analogue scale scores (r=-0.14; p=0.02). Comparably, a statistically significant correlation was evident between APCSA and %FI (r=-0.40; p=0.02) on analysis.Conclusion:The results of our study demonstrate a statistically significant relationship between APCSA and %FI in the multifidus and erector spinae muscles. Further significant associations of relatability were depicted with traditional clinical measures of sarcopenia. Thus, %FI may be a supplemental indicator of the sarcopenic status of patients presenting with chronic low back pain.

Patients presenting with degenerative spinal changes are often poor surgical candidates due to associated co-morbidities, frailty, or sarcopenia. Additionally, surgeries of a degenerative spine can prove difficult due to the distortion of normal surgical anatomy. Therefore, many patients are managed conservatively with a variety of modalities, including over-the-counter and prescription medications. Nevertheless, several patients do not experience adequate relief from pain with analgesic medications, precipitating multiple hospital visits, and usage of resources. As a result, back pain is regarded as a major economic burden, with total costs of associated treatment exceeding $100 billion annually. Pharmacogenetics is a relatively novel method of evaluating an individual’s response to analgesic medications, through analysis of germline polymorphisms. It entails obtaining a genetic sample, often via buccal swab or peripheral blood sample, and genetic analysis achieved through either polymerase chain reaction +/− Sanger sequencing, microassays, restriction length fragment polymorphism analysis, or genetic library preparation and next generation sequencing. The potential efficacy of pharmacogenetic analysis has been highlighted across several specialities to date. However, a paucity of evidence exists regarding spine surgery populations. Nevertheless, regular prospective pharmacogenetic analysis may ultimately prove beneficial when concerning degenerative spinal cohorts due to aforementioned surgical and economic considerations. The purpose of this narrative review is to outline how metaboliser profile variants affect the pharmacokinetics of specific analgesia used to treat back pain, and to discuss the current potential and limitations of employing regular pharmacogenetic analysis for spine surgery populations with degenerative conditions.

BACKGROUND: The preoperative identification of osteoporosis in the spine surgery population is of crucial importance. Limitations associated with dual-energy x-ray absorptiometry, such as access and reliability, have prompted the search for alternative methods to diagnose osteoporosis. The Hounsfield Unit (HU), a readily available measure on computed tomography, has garnered considerable attention in recent years as a potential diagnostic tool for reduced bone mineral density. However, the optimal threshold settings for diagnosing osteoporosis have yet to be determined. METHODS: We selected studies that included comparison of the HU (index test) with dual-energy x-ray absorptiometry evaluation (reference test). Data quality was assessed using the standardised QUADAS-2 criteria. Studies were characterised into 3 categories, based on the threshold of the index test used with the goal of obtaining a high sensitivity, high specificity or balanced sensitivity-specificity test. RESULTS: 9 studies were eligible for meta-analysis. In the high specificity group, the pooled sensitivity was 0.652 (95% CI 0.526 - 0.760), specificity 0.795 (95% CI 0.711 - 0.859) and diagnostic odds ratio was 6.652 (95% CI 4.367 - 10.133). In the high sensitivity group, the overall pooled sensitivity was 0.912 (95% CI 0.718 - 0.977), specificity was 0.67 (0.57 - 0.75) and diagnostic odds ratio was 19.424 (5.446 - 69.275). In the balanced sensitivity-specificity group, the overall pooled sensitivity was 0.625 (95% CI 0.504 - 0.732), specificity was 0.914 (0.823 - 0.960) and diagnostic odds ratio was 14.880 (7.521 - 29.440). Considerable heterogeneity existed throughout the analysis. CONCLUSION: In conclusion, the HU is a clinically useful tool to aide in the diagnosis of osteoporosis. However, the heterogeneity seen in this study warrants caution in the interpretation of results. We have demonstrated the impact of differing HU threshold values on the diagnostic ability of this test. We would propose a threshold of 135 HU to diagnose OP. Future work would investigate the optimal HU cut-off to differentiate normal from low bone mineral density. (C) 2021 Elsevier Inc. All rights reserved.

Degenerative disk disease is a pathologic state associated with axial skeletal pain, radiculopathy, and myelopathy, and will inevitably increase in prevalence in parallel with an aging population. The objective of regenerative medicine is to convert the inflammatory, catabolic microenvironment of degenerative disease into an anti-inflammatory, anabolic environment. This comprehensive review discusses and outlines both in vitro and in vivo efficacy of regenerative treatment modalities for degenerative disk disease, such as; mesenchymal stem cells, gene therapy, tissue engineering, and biologic treatments. To date, clinical applications have been limited secondary to a lack of standardized high quality clinical data. Additional research should focus on determining the optimal cellular makeup and concentration for each of these interventions. Nevertheless, modern medicine provides a new avenue of confronting disease, with methods surpassing traditional methods of removing the pathology in question, as regenerative medicine provides the opportunity to recover from the diseased state.

BACKGROUND:The SARS-CoV-2 pandemic has had profound implications on healthcare institutions. AIMS:This study aims to assess and compare referral patterns during COVID-19 to corresponding dates for the preceding 3 years (2017-2019), in order to preemptively coordinate the logistics of the surgical unit for similar future experiences. METHODS:Retrospective review for our institution, a national tertiary referral centre for spine pathology. Two distinct time-points were chosen to represent the varied levels of social restriction during the current pandemic: (i) study period 1 (SP1) from 11 November 2020 to 08 June 2020 represents a national lockdown, and (ii) study period 2 (SP2) from 09 June 2020 to 09 September 2020 indicates an easing of restrictions. Both periods were compared to corresponding dates (CP1: 11 March-08 June and CP2 09 June-09 September) for the preceding 3 years (2017-2019). Data collected included age, gender, and mechanism of injury (MOI) for descriptive analyses. MOIs were categorised into disc disease, cyclist, road-traffic-accident (RTA), falls < 2 m, falls > 2 m, malignancy, sporting injuries, and miscellaneous. RESULTS:All MOI categories witnessed a reduction in referral numbers during SP1: disc disease (-29%), cyclist (-5%), RTAs (-66%), falls < 2 m (-39%), falls > 2 m (-17%), malignancy (-33%), sporting injuries (-100%), and miscellaneous (-58%). Four of 8 categories (RTAs, falls < 2 m, malignancy, miscellaneous) showed a trend towards return of pre-lockdown values during SP2. Two categories (disc disease, falls > 2 m) showed a further reduction (-34%, -27%) during SP2. One category (sporting injuries) portrayed a complete return to normal values during SP2 while a notable increase in cyclist-related referrals was witnessed (+ 63%) when compared with corresponding dates of previous years. CONCLUSION:Spinal injury continues to occur across almost all categories, albeit at considerably reduced numbers. RTAs and falls remained the most common MOI. Awareness needs to be drawn to the reduction of malignancy-related referrals to dissuade people with such symptoms from avoiding presentation to hospital over periods of social restrictions.

Any investigation for the surgical assessment of spinal pain should enable the accurate localization of the source of pain and aid in potential surgical planning. In the setting of suspected discogenic neck and back pain, it is crucial to correctly identify the pain-generating disk or disks. In recent years, the development of high-quality, less-invasive imaging techniques has resulted in concerns as regards the appropriateness of an invasive procedure, such as discography, as the gold standard diagnostic tool for the surgical assessment of degenerative disk disease. This article will briefly argue, first, why discography should remain the gold-standard investigation, and, second, why single photon emission computed tomography (SPECT) should supplant it.

S imilar to other industries, the implementation of artificial intelligence (AI) has been progressively accepted into the health care sector over the last 2 decades, with benefits evident in specialties predominated by image analysis.1–3 In spine surgery, the majority of new technologies have been swiftly welcomed, highlighting its desire to constantly evolve as a specialty. However, AI implementation is yet to be widely used by the spine surgery community—potentially because of its relative youth. Thus, the question remains whether or not the integration of AI into spine surgery is feasible and can prove a useful asset to improve the current standard of spine care. Perhaps the greatest challenge to the widespread use of AI in health care delivery is reproducing the physician’s clinical expertise.1 This was confuted in a study by Olczak et al,4 who attempted to design a prototype of an AI deep learning model that accurately mimics human neural networks to interpret orthopedic trauma radiographs.4 Results showed that the models were able to identify laterality, body part, and examination view with an accuracy of at least 90%, and fracture detection with an 83% accuracy rate.4 Other machine learning (ML) techniques such as decision trees, gradient-boasting machines, neural networks, and random forests have also shown accurate prognostic validity in comparison with traditional methods used in neurosurgical and spine care practices.5 In contrast to traditional logistic regression predictive tools, artificial neural networks (ANNs) are part of the deep learning subgroup of AI computational models used to analyze complex relationships in data and solve nonalgorithmic problems.6 ANNs have been used as a diagnostic tool in lower back pain, scoliosis, spinal deformities, and congenital abnormalities, in addition to interpreting radiographic images.7–9 Other uses of ANNs in spinal surgery include biomechanical assessments of spinal pathologies by interpreting spinal loads,10 muscle strength,10 design optimization of pedicle screws,11 and low bone mineral density prediction.12 Arjmand et al10 designed and tested 2 ANNs for spinal load and muscle force evaluation during static lifting of a complex trunk finite element model compared with regression equation mapping. The root mean square error (RMSE) value was evaluated for both ANN models and compared with the regression equation model. Results showed that ANNs performed more accurately for spinal load (RMSE=20.7N, R=99%) and muscle force (RMSE=4.7 N, R=99%) mapping compared with regression equations [spinal loads (RMSE=120.4N, R=99%) and muscle forces (RMSE=43.2N, R=94%)].10 The efficacy of ANNs has also been demonstrated in biomechanical studies to optimize pedicle screw design to improve failure rates in short-segment instrumentation of spine fractures. Amaritsakul et al11 report the optimal screw design developed through a multiobjective genetic algorithm approach showed to have higher fatigue life (P< 0.01) and similar pull-out strength to commercial counterparts.11 In addition, ANNs can be used as a prediction tool in mass screenings, as applied in a study by Sadatsafavi et al12 who sought to predict bone density among postmenopausal woman. The predictive power of ANN was tested against conventional prediction methods of bone mineral density in postmenopausal women from a database of 10 input variables (age, weight, year since menopause, corticosteroid use, estrogen use, number of gravidities, age of menarche, height, exercise, and smoking habit) and 2 outputs (lumbar spine and femoral neck T-score).12 As the number of variables input into the models increased, ANNs performed better than their linear regression model counterparts. Results demonstrated that ANN models with ≥ 5 variables [area under the Received for publication September 13, 2020; accepted November 7, 2020. From the *School of Medicine, Trinity College Dublin; †School of Medicine, University College Dublin; ‡Royal College of Surgeons in Ireland, St. Stephen’s Green; and §National Spinal Injuries Unit, Department of Trauma & Orthopaedics Surgery, Mater Misericordiae University Hospital, Dublin, Ireland. The authors declare no conflict of interest. Reprints: Jake M. McDonnell, MBBCh, BAO, Royal College of Surgeons, Ireland, 123 St. Stephen’s Green, Dublin D02 YN77, Ireland (e-mail: jakemcdonnell@rcsi.com). Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved. CONTROVERSIES IN SPINE SURGERY

Background: The surgical management of adult spinal deformity (ASD) is a major surgical undertaking associated with considerable perioperative risk and a substantial complication profile. Although the natural history and risk factors associated with proximal junctional kyphosis (PJK) and proximal junctional failure are widely reported, distal junctional failure (DJF) is less well understood. Study Design: A systematic review was carried out. Objectives: The primary objective is to identify the risk factors associated with DJF. The secondary objective is to delineate the incidence rate and causative factors associated with DJF. Methods: A systematic review of articles in Medline/PubMed and The Cochrane Library databases was performed according to preferred reporting items for systematic reviews and meta-analyses guidelines. Data was collated to determine the prevalence of DJF and overall revision rates, and identify potential risk factors for development of DJF. Results: Twelve studies were included for systematic review. There were 81/2261 (3.6%) cases of DJF. Overall, DJF represented 27.3% of all revision surgeries. Anterior-posterior surgery had a reduced incidence of postoperative DJF [5.0% vs. 8.7%; P = 0.08; relative risk (RR) = 1.73], as did patients below 60 years of age at the time of surgery (2.9% vs. 3.9%; P=0.09; RR= 1.34). There was a higher incidence of DJF among those patients who received interbody fusion (9.9% vs. 5.1%; P=0.06; RR = 1.93) compared with those who did not. However, none of these findings reached statistical significance. There were significantly more rates of DJF for fusions ending on L5 compared with constructs fused to the sacrum (11.7% vs. 3.6%; P=0.02; RR = 3.28). Conclusions: Cohorts 60 years and above of age at the time of surgery and patients managed with posterior-only fusion or interbody fusion have increased incidences of DJF. Fusion to L5 instead of the sacrum significantly influences DJF rates. However, the quality of available evidence is low and further high-quality studies are required to more robustly analyze the clinical, radiographic, and surgical risk factors associated with the development of DJF after ASD surgery.

INTRODUCTION:The Orthopaedic Trauma Association has recommended limitation of in-person encounters to absolute necessity. One method of ensuring standard patient care within these guidelines is through the implementation of telemedicine. AIMS:To evaluate the efficacy of telemedicine for elective orthopaedic patients in the recovery and/or rehabilitation period. METHODS:A systematic review and meta-analysis of articles in Medline/PubMed and The Cochrane Library databases was performed according to the PRISMA guidelines for prospective randomised controlled trials to compare clinical and symptomatic measures for elective patients managed routinely with remote care compared to those managed with standard in-clinic management. To be included for meta-analysis, parameters must be evaluated in ≥3 studies. RESULTS:Eleven studies were included in the meta-analyses. Both telemedicine and control cohorts were comparable for patient satisfaction (RR, 0.98; 95% CI, 0.90-1.07; I2 = 0%; p = 0.52) and patient retention analysis (RR, 1.25; 95% CI, 0.51-3.06; p = 0.54; I2 = 0%). Similarly, there was no statistical difference appreciated between cohorts for overall Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (p = 0.30), Timed Up and Go Test (p = 0.40), and Stair Test (p = 0.18). Significant difference did exist for visual analogue scale (VAS) scores (p = 0.02) in favour of in-clinic management. CONCLUSION:Telemedicine will serve an integral aspect of healthcare delivery throughout the current COVID-19 pandemic and beyond in an effort to deliver safe, efficient and time-sensitive care to the orthopaedic patient population. The results of our meta-analyses indicate that virtual consultations are as effective as traditional in-person consultations for the care of elective orthopaedic patients in the recovery and rehabilitation period. However, further studies are needed to evaluate for initial consultations and certain sub-specialties of orthopaedics.

In recent years, machine learning (ML) and artificial neural networks (ANNs), a particular subset of ML, have been adopted by various areas of healthcare. A number of diagnostic and prognostic algorithms have been designed and implemented across a range of orthopaedic sub-specialties to date, with many positive results. However, the methodology of many of these studies is flawed, and few compare the use of ML with the current approach in clinical practice. Spinal surgery has advanced rapidly over the past three decades, particularly in the areas of implant technology, advanced surgical techniques, biologics, and enhanced recovery protocols. It is therefore regarded an innovative field. Inevitably, spinal surgeons will wish to incorporate ML into their practice should models prove effective in diagnostic or prognostic terms. The purpose of this article is to review published studies that describe the application of neural networks to spinal surgery and which actively compare ANN models to contemporary clinical standards allowing evaluation of their efficacy, accuracy, and relatability. It also explores some of the limitations of the technology, which act to constrain the widespread adoption of neural networks for diagnostic and prognostic use in spinal care. Finally, it describes the necessary considerations should institutions wish to incorporate ANNs into their practices. In doing so, the aim of this review is to provide a practical approach for spinal surgeons to understand the relevant aspects of neural networks. Cite this article: Bone Joint J 2021;103-B(9):1442-1448.

For 3D bioprinted tissues to be scaled-up to clinically relevant sizes, effective prevascularisation strategies are required to provide the necessary nutrients for normal metabolism and to remove associated waste by-products. The aim of this study was to develop a bioprinting strategy to engineer prevascularised tissues in vitro and to investigate the capacity of such constructs to enhance the vascularisation and regeneration of large bone defects in vivo. From a screen of different bioinks, a fibrin-based hydrogel was found to best support human umbilical vein endothelial cell (HUVEC) sprouting and the establishment of a microvessel network. When this bioink was combined with HUVECs and supporting human bone marrow stem/stromal cells (hBMSCs), these microvessel networks persisted in vitro. Furthermore, only bioprinted tissues containing both HUVECs and hBMSCs, that were first allowed to mature in vitro, supported robust blood vessel development in vivo. To assess the therapeutic utility of this bioprinting strategy, these bioinks were used to prevascularise 3D printed polycaprolactone (PCL) scaffolds, which were subsequently implanted into critically-sized femoral bone defects in rats. Micro-computed tomography (µCT) angiography revealed increased levels of vascularisation in vivo, which correlated with higher levels of new bone formation. Such prevascularised constructs could be used to enhance the vascularisation of a range of large tissue defects, forming the basis of multiple new bioprinted therapeutics. STATEMENT OF SIGNIFICANCE: This paper demonstrates a versatile 3D bioprinting technique to improve the vascularisation of tissue engineered constructs and further demonstrates how this method can be incorporated into a bone tissue engineering strategy to improve vascularisation in a rat femoral defect model.

Sarcopenia is characterized by progressive age-related and systematic loss of skeletal muscle mass, strength, and function. It was classified as an independent disease in 2016; thus, there is a sparsity of research on the association of sarcopenia with lower back pain and spinal diseases. Its prevalence is around 10% worldwide and it has been shown to be detrimental to quality of life in the elderly. Sarcopenia can be clinically identified by assessing muscle mass and physical performance measurements to show reduced strength (eg, grip strength chair rise and knee extensions) or function (eg, walking speed or distance). Radiographic imaging techniques such as computed tomography, ultrasound, or magnetic resonance imaging help diagnose sarcopenia in the lumbar spine by measuring either the cross-sectional area or the fatty infiltrate of the lumbar musculature. The presence of sarcopenia in patients preoperatively may lead to worse postoperative outcomes. Research in the treatment options for sarcopenia presurgery is still in its infancy but exercise (both aerobic and resistance exercise have been found to slow down the rate of decline in muscle mass and strength with aging) and nutrition have been utilized to varying success and show great promise in the future.

Background: Diagnosis and appropriate management of traumatic cervical fractures is important due to secondary neurological sequelae and permanent disability that can arise. For fractures requiring surgical fixation 1-stage surgery is appealing in favour of 2-stage surgery due to reduced intraoperative time and potential subsequent complications. However certain patients fail a 1-stage anterior approach. The purpose of this study is to identify patient-and injury-specific factors associated with failure in 1-stage anterior fixation to optimise the treatment of traumatic cervical fractures. Methods: A retrospective study was performed at our institution from June 22nd 2016 to August 14th 2019 to identify patients that suffered traumatic cervical fractures and were managed surgically with a 1-stage anterior cervical discectomy and fusion (ACDF). Data collated included demographic parameters, fracture characteristics, associated injuries, and characteristics of fusion surgeries. Statistical analysis involved t-test of independent means, and z-test of proportions where applicable. Results: Twenty-two patients were identified. Five patients (22.7%) failed the 1-stage ACDF approach and required subsequent second-stage posterior instrumentation. Statistically significant parameters that influenced 1-stage ACDF failure were age discrepancy between cohorts (65.2 vs. 50.2, P<0.04) and injuries requiring cervico-thoracic junctional stabilization due to instability (60% vs. 11.7%, P<0.01). Conclusions: The definitive management of traumatic cervical fractures remains a surgical challenge. The results of our study indicate that older patients and injuries at the cervicothoracic junction have a higher risk of failure with 1-stage ACDF. Thus, the authors recommend considering 2-stage anterior-posterior fusion in elderly patients and in injuries at the cervicothoracic junction.