A Mechanistic and Preclinical Assessment of BioRestore Bioactive Glass as a Synthetic Bone Graft Extender and Substitute for Osteoinduction and Spine Fusion.

STUDY DESIGN: Preclinical animal study. OBJECTIVE: Evaluate the osteoinductivity and bone regenerative capacity of BioRestore bioactive glass. SUMMARY OF BACKGROUND DATA: BioRestore is a Food and Drug Administration (FDA)-approved bone void filler that has not yet been evaluated as a bone graft extender or substitute for spine fusion. METHODS: In vitro and in vivo methods were used to compare BioRestore with other biomaterials for the capacity to promote osteodifferentiation and spinal fusion. The materials evaluated (1) absorbable collagen sponge (ACS), (2) allograft, (3) BioRestore, (4) Human Demineralized Bone Matrix (DBM), and (5) MasterGraft. For in vitro studies, rat bone marrow-derived stem cells (BMSC) were cultured on the materials in either standard or osteogenic media (SM, OM), followed by quantification of osteogenic marker genes (Runx2, Osx, Alpl, Bglap, Spp1) and alkaline phosphatase (ALP) activity. Sixty female Fischer rats underwent L4-5 posterolateral fusion (PLF) with placement of 1 of 5 implants: (1) ICBG from syngeneic rats; (2) ICBG+BioRestore; (3) BioRestore alone; (4) ICBG+Allograft; or (5) ICBG+MasterGraft. Spines were harvested 8 weeks postoperatively and evaluated for bone formation and fusion via radiography, blinded manual palpation, microCT, and histology. RESULTS: After culture for 1 week, BioRestore promoted similar expression levels of Runx2 and Osx to cells grown on DBM. At the 2-week timepoint, the relative ALP activity for BioRestore-OM was significantly higher (P<0.001) than that of ACS-OM and DBM-OM (P<0.01) and statistically equivalent to cells grown on allograft-OM. In vivo, radiographic and microCT evaluation showed some degree of bridging bone formation in all groups tested, with the exception of BioRestore alone, which did not produce successful fusions. CONCLUSIONS: This study demonstrates the capacity of BioRestore to promote osteoinductivity in vitro. In vivo, BioRestore performed similarly to commercially available bone graft extender materials but was incapable of producing fusion as a bone graft substitute. LEVEL OF EVIDENCE: Level V.

The Role of the Gut Microbiome in Orthopedic Surgery-a Narrative Review.

PURPOSE OF REVIEW: The importance of the gut microbiome has received increasing attention in recent years. New literature has revealed significant associations between gut health and various orthopedic disorders, as well as the potential for interventions targeting the gut microbiome to prevent disease and improve musculoskeletal outcomes. We provide a broad overview of available literature discussing the links between the gut microbiome and pathogenesis and management of orthopedic disorders. RECENT FINDINGS: Human and animal models have characterized the associations between gut microbiome dysregulation and diseases of the joints, spine, nerves, and muscle, as well as the physiology of bone formation and fracture healing. Interventions such as probiotic supplementation and fecal transplant have shown some promise in ameliorating the symptoms or slowing the progression of these disorders. We aim to aid discussions regarding optimization of patient outcomes in the field of orthopedic surgery by providing a narrative review of the available evidence-based literature involving gut microbiome dysregulation and its effects on orthopedic disease. In general, we believe that the gut microbiome is a viable target for interventions that can augment current management models and lead to significantly improved outcomes for patients under the care of orthopedic surgeons.

Advances in Synthetic Grafts in Spinal Fusion Surgery.

Degenerative spine disease is increasing in prevalence as the global population ages, indicating a need for targeted therapies and continued innovations. While autograft and allograft have historically demonstrated robust results in spine fusion surgery, they have significant limitations and associated complications such as infection, donor site morbidity and pain, and neurovascular injury. Synthetic grafts may provide similar success while mitigating negative outcomes. A narrative literature review was performed to review available synthetic materials that aim to optimize spinal fusion. The authors specifically address the evolution of synthetics and comment on future trends. Novel synthetic materials currently in use include ceramics, synthetic polymers and peptides, bioactive glasses, and peptide amphiphiles, and the authors focus on their success in both human and animal models, physical properties, advantages, and disadvantages. Advantages include properties of osteoinduction, osteoconduction, and osteogenesis, whereas disadvantages encompass a lack of these properties or growth factor-induced complications. Typically, the use of synthetic materials results in fewer complications and lower costs. While the development and tuning of synthetic materials are ongoing, there are many beneficial alternatives to autografts and allografts with promising fusion results.

The Role of Cervical Disc Arthroplasty in Elite Athletes.

PURPOSE OF REVIEW: Cervical disc arthroplasty (CDA) for the treatment of symptomatic cervical disc herniations (CDH) is a promising treatment for professional athletes. In recent years, a number of high-profile athletes have returned to professional play within three months after CDA, raising important questions about the potential of this procedure within this patient group. We provide the first comprehensive review of available literature for the safety and efficacy of CDA in professional contact sport athletes. RECENT FINDINGS: CDA provides theoretical biomechanical advantages over anterior cervical discectomy and fusion (ACDF) and posterior foraminotomy (PF), as CDA is the only operation for treatment of CDH that provides neural decompression, stability and height restoration, with preserved range of motion. While the comparative long-term results from each procedure are unknown, CDA has provided encouraging promise in its use in professional contact athletes. We aim to aid ongoing discussions regarding the controversies in spine surgery for professional athletes by providing a scientific review of the available evidence-based literature involving cervical disc arthroplasty in this population. In general, we believe that CDA is a viable alternative to ACDF and PF for the contact professional athlete who requires full neck range of motion and desires an expedited return to play. For collision athletes, the short- and long-term safety and efficacy profile of this procedure is promising but still unclear.

Congenital Cervical Stenosis: a Review of the Current Literature.

PURPOSE OF REVIEW: Congenital cervical stenosis (CCS) is a phenomenon in which an individual has a narrow canal due to abnormal anatomy which can present with earlier degenerative symptoms due to a reduced sagittal diameter. The diagnosis of CCS is important to individual treatment and preventative measures. Often, athletes are warned against sport participation that may cause damage to the cervical spine. There may be a predisposition in certain populations, but lack of data limits conclusions. The current review investigates recent literature on the definition, pathoanatomy, clinical presentation, and management of CCS. It specifically interrogates potential populations predisposed to this condition. RECENT FINDINGS: The current literature reveals a potential predisposition for CCS in the black population when compared to the white population; however, many studies do not report race when discussing CCS patients. The lack of data limits a consensus on specific populations with a congenitally narrow canal. CCS may be more prevalent in specific populations. With knowledge of populations more at risk for this condition, physicians and teams can be alert when evaluating players and young adults. Furthermore, this may provide insight into risk for symptoms with degenerative disease. These findings introduce an avenue for further research into CCS.

The Top 50 Most Cited Articles on the Medial Patellofemoral Ligament (MPFL): A Bibliometric Analysis.

Objectives: To determine which original articles on the topic of the medial patellofemoral ligament (MPFL) have been cited the most in the literature utilizing a bibliometric approach. Secondarily, to determine temporal trends between article types. Methods: Articles on the topic of the MPFL were identified by utilizing the Web of Science Database. The search yielded 1596 results and the top 50 cited original articles were collected for further analysis. The following information was gathered for all included articles: title, first author's name, journal name, year of publication, impact factor of the journal in 2021, total number of citations of the article, average citations per year (ACY), geographic origin, institutions, research theme, and keywords. Articles were then grouped into one of three categories: cadaveric/anatomic, clinical, and radiologic. Results: The total number of citations was 10,393. Most were published between the years 2000-2009 (66%) and in the journal, American Journal of Sports Medicine (34%). The mean ACY was 11.73 ± standard deviation 5.86 and the Kawasaki Municipal Hospital was the institution with the most articles included in the top 50 (n = 6, 12%). The top-cited articles focused on 3 themes: cadaveric/anatomic (n = 18, 36%), clinical (n = 25, 50%), and radiologic (n = 7, 14%). Cadaveric/anatomic articles had the highest average number of citations at 271.4 ± 153.9, followed by radiologic (173.3 ± 53.0) and clinical articles (171.8 ± 102.4). Over time, clinical articles were more likely to be included in the top 50 list, compared to cadaveric/anatomic/radiologic articles. Conclusion: The most impactful MPFL articles relate to cadaveric/anatomic articles; however, over time, clinical articles became more prevalent.

The Role of Preoperative Vitamin D in Spine Surgery.

PURPOSE OF REVIEW: Vitamin D is an essential micronutrient for human bone health and maintenance. Patients undergoing orthopaedic surgery with hypovitaminosis D may be at greater risk for worsened clinical outcomes. This narrative review aims to compile the current literature studying the effects of low preoperative vitamin D on spine surgery outcomes, creating a resource that clinicians can use to inform their practice. RECENT FINDINGS: Vitamin D deficiency predisposes to worse outcomes following spine surgery. Vitamin D supplementation may be beneficial in reducing the risk for adverse postoperative events; however, the literature is inconclusive regarding its efficacy in improving bone density and fracture risk. Spine clinicians should be aware of the increased risk for poor outcomes in patients with preoperative vitamin D deficiency. Future investigations are needed to better evaluate the benefits of preoperative vitamin D screening and supplementation on improving surgical outcomes in spine patients. These studies must also consider the effects on perioperative healthcare costs.

Imaging findings and interventional management of deep venous thrombosis.

Deep venous thrombosis (DVT) is a subtype of venous thromboembolism. Lower extremity DVT affects about 1-2% of hospitalized patients. If not managed properly, these thrombi can embolize, causing further complications. Thrombosis risk factors include vascular endothelial injury, venous stasis, and hypercoagulability states. This triad is also known as Virchow's triad. Although clinical features of lower extremity DVT are nonspecific and many patients are asymptomatic, physicians should maintain a high index of suspicion in patients presenting with leg swelling, pain, warmth, and erythema. Several diagnostic approaches for suspected first DVT have been proposed, and management depends on multiple factors such as location, duration of symptoms, cause of the thrombosis, and recurrence rate.

Biographies of international women leaders in neurosurgery.

We received so many biographies of women neurosurgery leaders for this issue that only a selection could be condensed here. In all of them, the essence of a leader shines through. Many are included as "first" of their country or color or other achievement. All of them are included as outstanding-in clinical, academic, and organized neurosurgery. Two defining features are tenacity and service. When faced with shocking discrimination, or numbing indifference, they ignored it or fought valiantly. When choosing their life's work, they chose service, often of the most neglected-those with pain, trauma, and disability. These women inspire and point the way to a time when the term "women leaders" as an exception is unnecessary.-Katharine J. Drummond, MD, on behalf of this month's topic editors.

Superior Colliculus Lesions Lead to Disrupted Responses to Light in Diurnal Grass Rats (Arvicanthis niloticus).

The circadian system regulates daily rhythms of physiology and behavior. Although extraordinary advances have been made to elucidate the brain mechanisms underlying the circadian system in nocturnal species, less is known in diurnal species. Recent studies have shown that retinorecipient brain areas such as the intergeniculate leaflet (IGL) and olivary pretectal nucleus (OPT) are critical for the display of normal patterns of daily activity in diurnal grass rats (Arvicanthis niloticus). Specifically, grass rats with IGL and OPT lesions respond to light in similar ways to intact nocturnal animals. Importantly, both the IGL and OPT project to one another in nocturnal species, and there is evidence that these 2 brain regions also project to the superior colliculus (SC). The SC receives direct retinal input, is involved in the triggering of rapid eye movement sleep in nocturnal rats, and is disproportionately large in the diurnal grass rat. The objective of the current study was to use diurnal grass rats to test the hypothesis that the SC is critical for the expression of diurnal behavior and physiology. We performed bilateral electrolytic lesions of the SC in female grass rats to examine behavioral patterns and acute responses to light. Most grass rats with SC lesions expressed significantly reduced activity in the presence of light. Exposing these grass rats to constant darkness reinstated activity levels during the subjective day, suggesting that light masks their ability to display a diurnal activity profile in 12:12 LD. Altogether, our data suggest that the SC is critical for maintaining normal responses to light in female grass rats.

The effects of ambient temperature and lighting intensity on wheel-running behavior in a diurnal rodent, the Nile grass rat (Arvicanthis niloticus).

Environmental conditions, such as the light-dark cycle and temperature, affect the display of circadian rhythmicity and locomotor activity patterns in mammals. Here, we tested the hypothesis that manipulating these environmental conditions would affect wheel-running activity patterns in a diurnal rodent, the Nile grass rat (Arvicanthis niloticus). Grass rats are diurnal in the field, however, a subset switch from a day-active pattern to a night-active pattern of activity after the introduction of a running wheel. The mechanism of this chronotype switch remains largely unknown. In the present study, grass rats were presented with running wheels in 12:12 light-dark conditions. First, subjects were exposed to 25 °C during the day and 21 °C at night, which resulted in 100% of grass rats expressing diurnal behavior. Subjects were then exposed to manipulations of elevated ambient temperature, which resulted in a significant reduction in wheel-running activity. Reducing ambient temperature below 21 °C, however, did not disrupt the expression of diurnality or overall activity. Next, lighting intensity was reduced, which resulted in a switch from a diurnal to a nocturnal chronotype in a subset of animals and reduced overall wheel-running activity. Upon return to baseline lighting intensity, patterns of diurnal activity were restored. Altogether, increases in ambient temperature and decreases in lighting intensity significantly reduced overall wheel-running activity. Importantly, dim light resulted in a temporal niche switch in a subset of grass rats, suggesting a critical role for lighting intensity on the expression of wheel-running activity patterns. (PsycINFO Database Record (c) 2019 APA, all rights reserved).