Facet Violation With Percutaneous Pedicle Screw Placement: Impact of 3D Navigation and Facet Orientation

Background: The gold standard for percutaneous pedicle screw placement is 2-dimensional (2D) fluoroscopy. Data are sparse on the accuracy of 3-dimensional (3D) navigation percutaneous screw placement in minimally invasive spine procedures. Objective: We sought to compare a single surgeon's percutaneous pedicle screw placement accuracy using 2D fluoroscopy versus 3D navigation, as well as to investigate the effect of facet orientation on facet violation when using 2D fluoroscopy. Methods: We conducted a retrospective radiographic study of consecutive cohort of patients who underwent percutaneous lumbar instrumentation using either 2D fluoroscopy or 3D navigation. All procedures were performed by a single surgeon at 2 academic institutions between 2011 and 2018. Radiographic measurement of screw accuracy was assessed using a postoperative computed tomographic scan. The primary outcome was facet violation, and secondary outcomes were endplate/tip breaches, the Gertzbein-Robbins classification for cortical breaches, and the Simplified Screw Accuracy grade. Statistical comparisons were made between screws placed using 2D fluoroscopy versus 3D navigation. Axial facet angles were also measured to correlate with facet violation rates. Results: In the 138 patients included, 376 screws were placed with fluoroscopy and 193 with navigation. Superior (unfused) level facet violation was higher with 2D fluoroscopy than with 3D navigation (9% vs 0.5%), which comprises the main cause for poor screw placement. Axial facet angles exceeding 45° at L4 and 60° at L5 were correlated with facet violations. Conclusion: This retrospective study found that 3D navigation is associated with lower facet violation rates in percutaneous lumbar pedicle screw placement when compared with 2D fluoroscopy. These findings suggest that 3D navigation may be of particular value when facet joints are coronally oriented.

The effect of nail diameter on proximal femoral shortening after internal fixation of pertrochanteric hip fractures with short cephalomedullary nails

Objective

Investigate the effect of distal nail diameter on proximal femoral shortening (PFS) after cephalomedullary nailing of hip fractures.

Methods

A retrospective cohort study of 80 patients aged 50 years and older with pertrochanteric hip fractures treated with a 10 or 11 mm short cephalomedullary nail (CMN) was performed. We measured abductor lever arm shortening, femoral height shortening, and PFS.

Results

There was no difference in abductor lever arm shortening (p = 0.09), femoral height shortening (p = 0.86), and PFS (p = 0.34) between the 10 and 11 mm groups.

Conclusions

Our results suggest that distal nail diameter does not affect PFS.

Level of evidence

III.

The most influential papers in direct anterior approach to total hip arthroplasty

Background

Citation analysis is a commonly used method for appraising the impact of academic publications within a particular field of study. A gap exists in the citation analysis literature with regard to the topic of direct anterior approach (DAA) hip arthroplasty. The purpose of this study is to identify the 50 most frequently cited publications related to this topic.

Methods

The Clarivate Analytics Web of Knowledge database was utilized to search for publications relating to DAA hip arthroplasty. The top 50 most cited articles that met inclusion criteria were recorded and reviewed for various metrics.

Results

The top 50 publications were cited a total of 3521 times, with an average of 86.3 total citations per year between 1980 and 2019. 47 of the 50 articles identified had been published since the year 2000. Cohort designs were the most common study type.

Conclusions

This analysis provides insight into factors that characterize highly cited articles on the specific topic of DAA hip arthroplasty. These factors include higher levels of evidence, recent publication, and origin in the United States. Citations of DAA hip arthroplasty papers appear to be on the rise. The curation and analysis of this set of 50 articles will provide orthopaedic surgery clinicians, researchers, and residency program directors a guide for quickly isolating influential articles on the topic of DAA hip arthroplasty. This may serve as a quick reference for clinical decision-making, foundation for further research, and curriculum on DAA hip arthroplasty.

Bilateral Neuropathy Dermatitis Following Simultaneous Bilateral Total Knee Arthroplasty: A Case Report

CASE

A 65-year-old man developed bilateral knee dermatitis in the distribution of the infrapatellar nerve 3 months following uncomplicated simultaneous bilateral total knee arthroplasty (TKA) for osteoarthritis. The patient was treated with topical corticosteroids, and the rash had resolved after 6 months. At the 2-year follow-up, there had been no recurrences.

CONCLUSION

Neuropathy dermatitis is a rare cutaneous complication of TKA. Although a few theories exist, there is no definitive explanation for the underlying pathophysiology of this disease process.

Distinguishing sleepiness and fatigue: focus on definition and measurement

Sleepiness and fatigue are two interrelated, but distinct phenomena; observed in a number of psychiatric, medical and primary sleep disorders. Despite their different implications in terms of diagnosis and treatment, these two terms are often used interchangeably, or merged under the more general lay term of 'tired'. Sleepiness is multidimensional and has many causes (multidetermined) and distinguished from fatigue by a presumed impairment of the normal arousal mechanism. Despite its ubiquity, no clear consensus exits as yet as to what constitutes sleepiness. Definitions of sleepiness, to date, are at best operational definitions, conceptualized so as to produce specific assessment instruments. As a result, while a number of subjective and objective measurement tools have been developed to measure sleepiness, each only captures a limited aspect of an otherwise heterogeneous entity. Fatigue is an equally complex phenomenon, its nature captured by a number of conceptualizations and definitions. Measures of fatigue have remained subjective, with a 'gold standard' for its measurement remaining elusive. Despite a high prevalence and high degree of morbidity, fatigue has remained a relatively under appreciated symptom, from both a clinical and research point of view.

Association of chromosome 7, chromosome 10 and EGFR gene amplification in glioblastoma multiforme

Glioblastoma multiforme (GBM) is characterized by intratumoral heterogeneity in both histomorphological and genetic changes, displaying a wide variety of numerical chromosome aberrations, the most common of which are trisomy 7 and monosomy 10. The amplification of the epidermal growth factor receptor (EGFR) gene is the most frequently reported genetic abnormality. The associations between these parameters and their implication in the tumoral progression are poorly understood. We performed simultaneous fluorescence in situ hybridization (FISH) with centromeric DNA probes for chromosomes 7 and 10 in smear preparations, and EGFR gene amplification by PCR from 25 cases of GBM. Trisomy/ polysomy for chromosome 7 was present in 76% of cases and monosomy 10 in 68%. Both alterations were associated in 56% of cases. The EGFR gene was amplified in 52% of tumors; in 44% associated with trisomy/ polysomy 7, and in 36% with monosomy 10. The three parameters were associated together in 28% of cases. Kaplan-Meier survival rate analysis demonstrated lower survival rates in patients with monosomy 10, trisomy 7, and monosomy associated with trisomy 7. The other combinations were not different in frequency in relation to survival. In the present study, trisomy/polysomy 7 and monosomy 10 have been found to be frequently associated. The combination of both anomalies is probably important in the tumorigenesis of glioblastoma. Moreover, this association is apparently independent of EGFR gene amplification, which could be a later event in this process.

Benefit-risk assessment of zaleplon in the treatment of insomnia

Insomnia is a heterogeneous, highly prevalent condition that is associated with a high level of psychiatric, physical, social and economic morbidity. The treatment of insomnia involves pharmacological and non-pharmacological interventions. The mainstay of pharmacological treatment of insomnia has been the benzodiazepines, the introduction of which represented a significant improvement over the barbiturates and chloral hydrate. Although benzodiazepines have been shown to be efficacious in treating insomnia, they have also been associated with a number of adverse effects including tolerance, dependence, withdrawal and abuse potential, impairment in daytime cognitive and psychomotor performance (including an increased risk of accidents and falls), adverse effects on respiration and the disruption of normal sleep architecture with reduction in both slow wave sleep and rapid eye movement. In the last decade, the treatment of insomnia has been supplemented by the introduction of a number of non-benzodiazepine hypnotics including zolpidem, zopiclone and, most recently, zaleplon. Zaleplon possesses a unique pharmacological profile, with an ultra-short half-life of about 1 hour, and selective binding to the BZ1(omega1) receptor subtypes of the GABA(A) receptor. This unique pharmacological profile predicts a number of pharmacodynamic properties that account for a unique benefit-risk profile. Consistent with these predictions, zaleplon has been shown in a number of studies to be efficacious in promoting sleep initiation, but less so in promoting sleep maintenance. The adverse effects associated with zaleplon have been shown to be more rapidly resolved and/or lesser in magnitude than those associated with benzodiazepines (including triazolam) and the longer acting non-benzodiazepine hypnotics (zolpidem and zopiclone). This improved risk profile includes: the effects of zaleplon on psychomotor and cognitive performance; tolerance, withdrawal and rebound; respiratory depression; sleep architecture; and other treatment-emergent adverse effects. The unique benefit-risk profile of this agent may be particularly suitable for certain patients with insomnia and provides yet another option in the management of this impairing condition.

Psychiatric aspects of late-life insomnia

Epidemiological trends towards a 'graying' population make the issue of insomnia in the elderly an increasingly important research and clinical topic. It is often challenging to determine how much of a psychiatric dimension there is to a clinical condition that is best viewed as both as a symptom and a true psychosomatic entity in its own right. To categorize insomnia as either psychiatric or medically based risks oversimplification of the complexities of sleep disruption in the elderly. Normal senescence-related changes in sleep architecture and circadian rhythms must be considered, as well as the frequent medical comorbidities that may affect sleep. Psychiatric diagnoses to consider include mood and anxiety disorders, which may be affected equally by physiological and psychological changes implicit in old age. Sleep disruption related to dementia is of particular interest to clinicians involved with patients in long-term care facilities. Insomnia may occasionally be iatrogenically induced or exacerbated, and particularly antidepressants must be carefully selected for this reason. Light therapy and behavior therapies are important in multimodal treatment of insomnia, and sleep hygiene includes both regular physical and social activities to preserve entrainment of circadian rhythms affecting sleep.

Large-scale quarantine following biological terrorism in the United States: scientific examination, logistic and legal limits, and possible consequences

Concern for potential bioterrorist attacks causing mass casualties has increased recently. Particular attention has been paid to scenarios in which a biological agent capable of person-to-person transmission, such as smallpox, is intentionally released among civilians. Multiple public health interventions are possible to effect disease containment in this context. One disease control measure that has been regularly proposed in various settings is the imposition of large-scale or geographic quarantine on the potentially exposed population. Although large-scale quarantine has not been implemented in recent US history, it has been used on a small scale in biological hoaxes, and it has been invoked in federally sponsored bioterrorism exercises. This article reviews the scientific principles that are relevant to the likely effectiveness of quarantine, the logistic barriers to its implementation, legal issues that a large-scale quarantine raises, and possible adverse consequences that might result from quarantine action. Imposition of large-scale quarantine-compulsory sequestration of groups of possibly exposed persons or human confinement within certain geographic areas to prevent spread of contagious disease-should not be considered a primary public health strategy in most imaginable circumstances. In the majority of contexts, other less extreme public health actions are likely to be more effective and create fewer unintended adverse consequences than quarantine. Actions and areas for future research, policy development, and response planning efforts are provided.

Lumbosacral fixation using expandable pedicle screws. an alternative in reoperation and osteoporosis

BACKGROUND CONTEXT

Pedicle screw fixation in osteoporotic bone and in revision of previous pedicle screw fixation cases presents a significant challenge to spine surgeons. Biomechanical tests have shown that a pedicle screw that expands within the vertebrae body can substantially improve fixation in the presence of compromised bone.

PURPOSE

To review the clinical and radiographic results with the use of expandable pedicle screws.

STUDY DESIGN

One hundred forty-five patients received one or more expandable pedicle screws from the Omega21 spinal fixation system (EBI, L.P., Parsippany, NJ) to obtain thorocolumbar or lumbosacral stabilization.

PATIENT SAMPLE

The indications for use of the expandable screws were osteoporosis (21 cases), reoperation of previous pedicle instrumentation (27 cases), intraoperative screw relocation (17 cases), construct reinforcement (23 cases), and sacral anchoring to avoid the necessity of anterior penetration of the sacral cortex (57 cases).

OUTCOME MEASURES

The presence of radiographic fusion and complications arising from the instrumentation were reviewed at a mean follow-up period of 35 months (range, 24-72 months).

METHODS

A retrospective clinical and radiographic review was performed. Fusion was evaluated based on anterior-posterior and lateral radiographs as well as dynamic radiographs in flexion and extension.

RESULTS

Radiographic evidence of fusion was obtained in 125 of the 145 cases (86%). Eighty-six percent of patients with osteoporosis and 89% of reoperations fused. There were no instances of screw loosening or pullout of the expandable screws. Screw breakage occurred in four patients (2.8%), including three patients where fusion was not obtained. In six patients the expandable screws were removed without difficulty after fusion because of local discomfort.

CONCLUSION

The results of this study have shown that expandable pedicle screws can be efficacious in cases in which pedicle screw fixation is difficult and adds a valuable tool to the growing armamentarium of spinal instrumentation.

Biomechanical evaluation and preliminary clinical experience with an expansive pedicle screw design

The advantages of pedicle screw fixation depend on their ability to retain bony purchase until the fusion mass is stable. Osteoporotic bone and removal and replacement of pedicle screws in revision procedures substantially reduce screw mechanical fixation strength and can lead to clinical failure. The objective of this study was to determine if an expansive pedicle screw design could be used to improve biomechanical fixation in bone of compromised quality. Axial mechanical pullout testing was performed on paired expansive and conventional pedicle screws placed in fresh, unembalmed cadaveric vertebrae. Bone mineral density measurements (made using a dual-energy X-ray absorption meter) were used to characterize bone quality. A preliminary clinical and radiographic evaluation of 14 patients was also performed at a minimum 2-year follow-up. The mean axial pullout force in bone of all qualities was increased 30% when the expansive pedicle screw design was used. This included an appropriate 50% increase in pullout force in bone of poor quality (low bone mineral density). The preliminary clinical and radiographic results were supportive of the biomechanical design rationale and mechanical testing. The results were similar to those expected for spinal instrumentation using pedicle screws, even though compromised bone was present in two thirds of the cases in which the expansive screw was used.

Extracellular nucleotides activate non-selective cation and Ca(2+)-dependent K+ channels in rat osteoclasts

1. Extracellular ATP elevates cytosolic free Ca2+ concentration ([Ca2+]i) in osteoclasts, but its effects on ion channels have not been reported previously. Membrane currents and [Ca2+]i were recorded in isolated rat osteoclasts using patch clamp and fluorescence techniques. 2. At negative membrane potentials, ATP (1-100 microM) activated an inward current that peaked rapidly and then declined. A later current was outward at potentials positive to the equilibrium potential for K+ (EK) and showed oscillations. 3. The initial inward current, studied in isolation using Cs+ in the electrode solution, showed rapid activation, inward rectification and reversal at +3 +/- 4 mV. Reduction of [Na+]o to 10 mM shifted the reversal potential to -21 +/- 3 mV, indicating that ATP activates a non-selective cation current, consistent with involvement of P2X receptors. 4. The later current activated by ATP, studied with K+ in the electrode solution, exhibited a linear I-V relationship, and reversed at -71 +/- 4 mV. The reversal potential shifted 51 mV per 10-fold change of [K+]o, indicating that ATP activates a K+ current (IK). 5. In fura-2-loaded cells, ATP caused elevation of [Ca2+]i that persisted in Ca(2+)-free solution, indicating that ATP induced release of Ca2+ from intracellular stores, consistent with involvement of P2Y receptors. Simultaneous patch clamp and fluorescence recordings revealed that IK was associated with the elevation of [Ca2+]i. Using a Ca2+ ionophore (4Br-A23187) to elevate [Ca2+]i, IK activated when [Ca2+]i exceeded approximately 400 nM, with half-maximal activation at 580 +/- 50 nM. 6. In cell-attached patches, ATP activated a channel with a conductance of 48 +/- 6 pS, that reversed director, near EK. Channel open probability increased with elevation of [Ca2+]i, indicating the Ca2+ dependence of this channel. 7. These results demonstrate that rat osteoclasts express two types of purinoceptors. P2X receptors give rise to non-selective cation current. P2Y receptors mediate Ca2+ release from stores, causing activation of a Ca(2+)-dependent K+ channel.

Cholinergic inhibition of Ca2+ current in guinea-pig gastric and tracheal smooth muscle cells

1. Cholinergic regulation of L-type Ca2+ channels was investigated in freshly dissociated guinea-pig gastric and tracheal smooth muscle cells. Acetylcholine (ACh, 50 microM) decreased Ca2+ channel current (ICa) by 37 +/- 3% (mean +/- S.E.M., 46 cells). 2. ACh reduced ICa at all voltages, with no shift in the current-voltage relationship. Effects of ACh were rapid (within 5 s) and repeatable, with multiple applications reproducibly inhibiting ICa in the continued presence of extracellular Ca2+ and in the presence of protein kinase C inhibitors. 3. The involvement of Ca2+ stores in this inhibition was investigated using Ca(2+)-free solution or cyclopiazonic acid (CPA) to deplete the stores. ACh initially inhibited ICa in the Ca(2+)-free solution (Na+ as charge carrier, 53 +/- 4% decrease, 18 cells) with subsequent responses significantly attenuated (n = 9). CPA (1 microM) reduced, then abolished, the effects of ACh on ICa (n = 5). 4. When studied in cell-attached patches (Ba2+ as charge carrier), ACh reduced Ca2+ channel open probability in twenty-two of thirty-six cells, consistent with the involvement of a diffusible cytosolic messenger. 5. ACh also inhibited ICa in tracheal muscle cells (reduction of 38 +/- 6% in 1 mM Ca2+, 4 cells; 77 +/- 3% in Ca(2+)-free solution, 7 cells). Furthermore, in cells where ACh elicited oscillating Ca(2+)-activated Cl- current, oscillatory inhibition of ICa was also observed (3 cells). 6. In summary, ACh causes rapid and reversible inhibition of ICa in gastric and tracheal muscles. Ca2+ stores were required to initiate this effect, with the rapid onset and oscillatory inhibition consistent with Ca2+ inhibition of the channel. Suppression of ICa would reduce Ca2+ entry during cholinergic excitation.

Buffered versus plain lidocaine as a local anesthetic for simple laceration repair

STUDY OBJECTIVE

Buffered lidocaine was compared with plain lidocaine as a local anesthetic for simple lacerations.

DESIGN

Randomized, double-blind, prospective clinical trial.

SETTING

Urban emergency department.

TYPE OF PARTICIPANTS

Ninety-one adult patients with simple linear lacerations were enrolled. Patients with allergy to lidocaine and patients with an abnormal mental status were excluded.

INTERVENTIONS

Each wound edge was anesthetized with either plain or buffered lidocaine using a randomized, double-blind protocol. The pain of infiltration was measured with a previously validated visual analog pain scale.

MEASUREMENTS AND MAIN RESULTS

Analysis of pooled data and paired data (using patients as their own controls) revealed that infiltrating buffered lidocaine was significantly less painful than plain lidocaine (P = .03 and P = .02, respectively). There was no significant difference in the anesthetic effectiveness of the two agents during suturing.

CONCLUSION

Buffered lidocaine is preferable to plain lidocaine as a local anesthetic agent for the repair of simple lacerations.

Sequential morphological and functional changes in kaolin-induced hydrocephalus

An experimental model of kaolin-induced hydrocephalus in the dog was studied in order to evaluate the progress of ventricular dilatation and the communications between the ventricular system and the subarachnoid space. Skull and spine radiological studies were obtained after metrizamide intraventricular injection, and the baseline ventricular pressure and cerebral pulse pressure amplitude were measured in anesthetized animals. Intracranial compliance and resistance to drainage of cerebrospinal fluid were calculated by means of bolus injection test. Light and scanning electron microscope studies were done at different developmental stages of hydrocephalus. With these experimental parameters, two successive phases were seen: an initial acute hypertensive hydrocephalus (H1) with high resistance, low compliance, severe ependymal damage, and subependymal edema; and a late chronic normotensive hydrocephalus (H2) with little resistance increase, normal compliance, epithelial regeneration, and subependymal gliosis. Both the H1 and H2 stages showed an increase in the cerebral pulse pressure amplitude.

Scanning and transmission electron microscopy of a craniopharyngioma: x-ray microanalytical study of the intratumoral mineralized deposits

This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.