Intrapartum cardiotocographic monitoring and its correlation with neonatal outcome.

Introduction: Despite the advancements in perinatal care in past decades, perinatal asphyxia remains a serious problem leading to significant perinatal morbidity and mortality. Therefore, foetal monitoring during the intrapartum period is of paramount importance. Among various methods of fetal monitoring, cardiotocography is a form of electronic foetal monitoring in which there is simultaneous recording of foetal heart rate and uterine contractions. Materials and Methods: This cross-sectional observational study was done in the labour room and neonatal intensive care unit (NICU) of a teaching Municipal Hospital in North India including 500 pregnant women of age group 18-45 years with singeleton fetus of gestation ≥36 weeks without any known congenital anomaly. Intrapartum cardiotocography (CTG) for 20 minutes was done within 12 hours prior to delivery and babies born to them were observed for birth asphyxia as Apgar score <7 at 1 minute as per using APGAR score less than 7 at 1 minute as per south east asia regional neonatal perinatal database (SEAR-NPD), world health organization (WHO) working definition. Results: CTG tracing was normal/reassuring in 92% of pregnant women, nonreassuring in 7% and was abnormal in only 1%. In patients with abnormal and nonreassuring CTG, delivery by lower segment cesarian section (LSCS) was significantly high (P < .0001). APGAR scoring was done at 1 minute and 5 minutes of life, it was found that 4% babies were having score less than 7 at 1 minute with incidence of birth asphyxia 40 per 1,000 live births Neonatal seizure was significantly more in nonreassuring and abnormal CTG group (P value <.0001). Conclusion: Abnormal CTG tracings result in higher incidence of operative interventions for deliveries. Abnormal CTG pattern during intrapartum CTG has high specificity and negative predictive value but has low sensitivity and positive predictive value for detection of birth asphyxia and need for NICU admission.

Biomechanics of the Sacroiliac Joint: Surgical Treatments.

BACKGROUND: Fixation is one of the most common surgical techniques for the treatment of chronic pain originating from the sacroiliac joint (SIJ). Many studies have investigated the clinical outcomes and biomechanics of various SIJ surgical procedures. However, the biomechanical literature points to several issues that need to be further explored, especially for the devices used in minimally invasive surgery of the SIJ. This study (part II) aims to assess biomechanical literature to understand the existing information as it relates to efficacies of the surgical techniques and the gaps in the knowledge base. Part I reviewed basic anatomy and mechanics of the SIJ joint, including difference between males and females, and causes of pain emanating from these joints. METHODS: A thorough literature review was performed pertaining to studies related to SIJ fixation techniques and the biomechanical outcomes of the surgical procedures. RESULTS: Fifty-five studies matched the search criteria and were considered for the review. These articles predominantly pertained to the biomechanical outcomes of the minimally invasive surgery with different instrumentation systems and surgical settings. CONCLUSIONS: The SIJ is one of the most overlooked sources of lower back pain. The joint is responsible for the pain in 15% to 30% of people suffering from lower back pain. Various studies have investigated the clinical outcomes of different surgical procedures intended to improve the pain and quality of life following surgery. The data show that these techniques are indeed effective. However, clinical studies have raised several issues, like optimal number and positioning of implants, unilateral versus bilateral placements, adjacent segment disease, implant designs, and optimal location of implants with respect to variations in bone density across the SIJ. Biomechanical studies using in vitro and in silico techniques have addressed some of these issues. Studies also point out the need for additional investigations for a better understanding of the underlying mechanics for the improved long-term surgical outcomes. Further long-term clinical follow-ups are essential as well. This review presents pertinent findings.

Implant Retention or Removal for Management of Surgical Site Infection After Spinal Surgery.

STUDY DESIGN: A literature review. OBJECTIVE: To summarize the implant removal rate, common bacterial organisms found, time of onset, ratio of superficial to deep infection, and regurgitating the prevalence among all the retrospective and prospective studies on management and characterization of surgical site infections (SSIs). METHODS: PubMed was searched for articles published between 2000 and 2018 on the management or characterization of SSIs after spinal surgery. Only prospective and retrospective studies were included. RESULTS: A total of 49 articles were found relevant to the objective. These studies highlighted the importance of implant removal to avoid recurrence of SSI. The common organisms detected were methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermis, Staphylococcus epidermis, Staphylococcus aureus, and Propionibacterium acnes, with prevalence of 1% to 15%. A major proportion of all were deep SSI, with minority reporting on late-onset SSI. CONCLUSION: Long-term antibiotics administration, and continuous irrigation and debridement were common suggestion among the authors; however, the key measure undertaken or implied by most authors to avoid risk of recurrence was removal or replacement of implants for late-onset SSI.

Updates on Evidence-Based Practices to Reduce Preoperative and Intraoperative Contamination of Implants in Spine Surgery: A Narrative Review.

The current communication seeks to provide an updated narrative review on latest methods of reducing implant contaminations used during spine surgery. Recent literature review has shown that both preoperative reprocessing and intraoperative handling of implants seem to contaminate implants. In brief, during preoperative phase, the implants undergo repeated bulk cleaning with dirty instruments from the OR, leading to residue buildup at the interfaces and possibly on the surfaces too. This, due to its concealed nature, remains unnoticed by the SPD (sterile processing department) or other hospital staff. Nevertheless, these can be avoided by using individually prepackaged presterilized implants. In the intraoperative phase, the implants (in the sterile field) are directly touched by the scrub tech with soiled (assisting the surgeon dispose the tissues from the instruments in use) gloves for loading onto an insertion device. It is then kept exposed on the working table (either separately or next to the used instruments as the pedicles hole are being prepared). Latest investigation has shown that by the time it is implanted in the patient, it can harbor up to 10e7 bacterial colony-forming units. The same implants were devoid of such colony-forming units, when sheathed by an impermeable sterile sheath around the sterile implant.

Biomechanics of the Sacroiliac Joint: Anatomy, Function, Biomechanics, Sexual Dimorphism, and Causes of Pain.

BACKGROUND: The sacroiliac joints (SIJs), the largest axial joints in the body, sit in between the sacrum and pelvic bones on either side. They connect the spine to the pelvis and thus facilitate load transfer from the lumbar spine to the lower extremities. The majority of low back pain (LBP) is perceived to originate from the lumbar spine; however, another likely source of LBP that is mostly overlooked is the SIJ. This study (Parts I and II) aims to evaluate the clinical and biomechanical literature to understand the anatomy, biomechanics, sexual dimorphism, and causes and mechanics of pain of the SIJ leading to conservative and surgical treatment options using instrumentation. Part II concludes with the mechanics of the devices used in minimal surgical procedures for the SIJ. METHODS: A thorough review of the literature was performed to analyze studies related to normal SIJ mechanics, as well as the effects of sex and pain on SIJ mechanics. RESULTS: A total of 65 studies were selected related to anatomy, biomechanical function of the SIJ, and structures that surround the joints. These studies discussed the effects of various parameters, gender, and existence of common physiological disorders on the biomechanics of the SIJ. CONCLUSIONS: The SIJ lies between the sacrum and the ilium and connects the spine to the pelvic bones. The SIJ transfers large bending moments and compression loads to lower extremities. However, the joint does not have as much stability of its own against the shear loads but resists shear due the tight wedging of the sacrum between hip bones on either side and the band of ligaments spanning the sacrum and the hip bones. Due to these, sacrum does not exhibit much motion with respect to the ilium. The SIJ range of motion in flexion-extension is about 3°, followed by axial rotation (about 1.5°), and lateral bending (about 0.8°). The sacrum of the female pelvis is wider, more uneven, less curved, and more backward tilted, compared to the male sacrum. Moreover, women exhibit higher mobility, stresses/loads, and pelvis ligament strains compared to male SIJs. Sacroiliac pain can be due to, but not limited to, hypo- or hypermobility, extraneous compression or shearing forces, micro- or macro-fractures, soft tissue injury, inflammation, pregnancy, adjacent segment disease, leg length discrepancy, and prior lumbar fusion. These effects are well discussed in this review. This review leads to Part II, in which the literature on mechanics of the treatment options is reviewed and synthesized.

A Multicenter Trial Demonstrating Presence or Absence of Bacterial Contamination at the Screw-Bone Interface Owing to Absence or Presence of Pedicle Screw Guard, Respectively, During Spinal Fusion.

STUDY DESIGN: A prospective multicenter study. OBJECTIVE: The objective of this study was to assess bacterial contamination in current practices of pedicle screw handling and comparing it to a novel method of using an intraoperative, sterile implant guard for screws. SUMMARY OF BACKGROUND DATA: Postoperative infections occur at the higher end of 2%-13%, as cited in the literature, and are underestimated due to various reasons in such publications. Despite concerns associated with vancomycin application immediately before closure, it is theoretically impossible to irrigate the screw-bone interface postimplantation. Consequently, any contamination of pedicle screw before implantation is permanent, and has the potential to cause deep-bone infection, or hardware loosening due to encapsulation of biofilm between the bone and the screw. Therefore, continued vigilance and effective preventive measures should be undertaken if available. MATERIALS AND METHODS: Two groups of presterile individually-packaged pedicle screws, one incased in a sterile, protective guard (group 1: G) and the other without such a guard (group 2: NG), 31 samples in each group were distributed over 28 spinal fusion surgeries at 5 independent hospitals groups. Each were loaded onto the insertion device by the scrub tech and left on the sterile table. Twenty minutes later, the lead surgeon who had just finished preparing the surgical site, handles the pedicle screw, to check the fit with the insertion device. Then, instead of implantation, it was transferred to a sterile container using fresh sterile gloves for bacterial analysis. RESULTS: The standard unguarded pedicle screws presented bioburden in the range of 10 to 10 colonies forming units per screw, whereas the guarded pedicle screws showed no bioburden. CONCLUSION: Standard, current, handling of pedicle screws leads to bacterial contamination, which can be avoided if the screws are sterilely prepackaged with an intraoperative guard (preinstalled).

Trends and predictors of coronary revascularization in patients with coronary artery anomalies and acute myocardial infarction: a nationwide analysis of 8131 patients.

OBJECTIVE: Acute myocardial infarction (AMI) is rarely associated with coronary artery anomalies (CAA). This confluence makes it difficult to identify and treat the culprit lesion with percutaneous coronary intervention (PCI). Our objective was to evaluate trends and predictors of revascularization in patients with CAA and AMI using a large national database. METHODS: We included adult patients with CAA presenting as ST segment elevation myocardial infarction (STEMI) or non-ST segment elevation myocardial infarction (NSTEMI) and undergoing coronary angiography from Nationwide Inpatient Sample from 2000 to 2011, using ICD-9 diagnosis code of 746.85 for CAA. Chi-square test for trend was used to compare revascularization rates over time. Multivariate logistic regression was used to identify predictors of revascularization. RESULTS: There were almost 4.7 million subjects with AMI undergoing coronary angiography from 2000 to 2011. Of these, there were 8131 patients with CAA, including 3425 STEMI and 4706 NSTEMI patients. Mean age of the CAA population was 59 years with 63.6% males. Overall PCI rate was 47.8% and coronary artery bypass grafting rate was 8.8%. In STEMI patients with CAA, PCI rate increased from 49.9% in 2000 to 77.8% in 2011 (P < 0.001). In NSTEMI patients with CAA, PCI rate remained unchanged from 33.3% in 2000 to 37.3% in 2011 (P = 0.34). Revascularization trends in AMI patients with CAA mirrored those in AMI patients without CAA. CONCLUSION: Despite the technical challenges associated with PCI in CAA, PCI rates in STEMI patients with CAA continue to increase over time. On the contrary, PCI rates continue to remain low in CAA patients with NSTEMI, reflecting overall contemporary NSTEMI treatment trends.

Multicenter study demonstrates radiomic features derived from magnetic resonance perfusion images identify pseudoprogression in glioblastoma.

Pseudoprogression (PsP) is a diagnostic clinical dilemma in cancer. In this study, we retrospectively analyse glioblastoma patients, and using their dynamic susceptibility contrast and dynamic contrast-enhanced perfusion MRI images we build a classifier using radiomic features obtained from both Ktrans and rCBV maps coupled with support vector machines. We achieve an accuracy of 90.82% (area under the curve (AUC) = 89.10%, sensitivity = 91.36%, 67 specificity = 88.24%, p = 0.017) in differentiating between pseudoprogression (PsP) and progressive disease (PD). The diagnostic performances of the models built using radiomic features from Ktrans and rCBV separately were equally high (Ktrans: AUC = 94%, 69 p = 0.012; rCBV: AUC = 89.8%, p = 0.004). Thus, this MR perfusion-based radiomic model demonstrates high accuracy, sensitivity and specificity in discriminating PsP from PD, thus provides a reliable alternative for noninvasive identification of PsP versus PD at the time of clinical/radiologic question. This study also illustrates the successful application of radiomic analysis as an advanced processing step on different MR perfusion maps.

Spinal Balance/Alignment - Clinical Relevance and Biomechanics.

In the normal spine due to its curvature in various regions, C7 plumb line (C7PL) passes through the sacrum so that the head is centered over the pelvis-ball and socket hip joints and ankle joints. This configuration leads to the least muscular activities to maintain the spinal balance. For any reason like deformity, scoliosis, kyphosis, trauma, and/or surgery this optimal configuration gets disturbed requiring higher muscular activity to maintain the posture and balance. Several parameters like the thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), Hip- and leg position influence the sagittal balance and thus the optimal configuration of spinal alignment. Global sagittal imbalance is energy consuming and often painful compensatory mechanisms are developed, that in turn negatively influence the quality of life. This review looks at the clinical aspects of spinal imbalance, and the biomechanics of spinal balance as dictated by the deformities- ankylosing spondylitis, scoliosis and kyphosis; surgical corrections- pedicle subtraction osteotomies and long segment stabilizations and consequent postural complications like the proximal and distal junctional kyphosis. This review suggests several potential research topics as well.

Harboring Contaminants in Repeatedly Reprocessed Pedicle Screws.

STUDY DESIGN: It consisted of evaluation of the pedicle screws for presence of residual nonmicrobial contaminants and tabulation of the minimum steps and time required for reprocessing implants as per guidelines and its comparison with actual practice. OBJECTIVE: An evaluation of the nonmicrobial contaminants prevalent on the pedicle screws used for spine surgery and the underlying practice cause behind the source. METHODS: The first component consisted of a random selection of 6 pedicle screws and its assessment using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The second component consisted of review of implant reprocessing guidelines and its applicability. RESULTS: Three types of contaminants were identified: corrosion, saccharide of unknown origin, and soap residue mixed with and were mostly present at the interfaces with low permeability. In addition, manufacturer's guideline recommends 19 hours of reprocessing, whereas the real-time observation revealed a turnaround time of 1 hour 17 minutes. CONCLUSION: Repeatedly reprocessed pedicle screws host corrosion, carbohydrate, fat, and soap, which could be a cause of surgical site infection and inflammatory responses postsurgery. The cause behind it is the impracticality of repeated cleaning and inspection of such devices.

Efficacy of Intraoperative Implant Prophylaxis in Reducing Intraoperative Microbial Contamination.

STUDY DESIGN: A prospective single-center study. OBJECTIVES: Assess to what degree contamination of pedicle screws occur in standard intraoperative practice and if use of an impermeable guard could mitigate or reduce such an occurrence. METHODS: Two groups of sterile prepackaged pedicle screws, one with an intraoperative guard (group 1) and the other without such a guard (group 2), each consisting of 5 samples distributed over 3 time points, were loaded onto the insertion device by the scrub tech and left on the sterile table. Approximately 20 minutes later, the lead surgeon who had just finished preparing the surgical site touches the pedicle screw. Then instead of implantation it was transferred to a sterile container using fresh clean gloves for bacterial and gene analysis. Guarded screw implies that even after unwrapping from the package, the screw carries an impermeable barrier along its entire length, which is only removed seconds prior to implantation. RESULTS: The standard unguarded pedicle screws presented bioburden in the range of 105 to 107 (colony forming units/implant) with bacterial genus mostly consisting of Staphylococcus and Micrococcus, the 2 most common genera found in surgical site infection reports. The common species among them were Staphylococcus epidermis, Staphylococcus aureus, Micrococcus luteus, and Staphylococcus pettenkoferi, whereas the guarded pedicle screws showed no bioburden. CONCLUSIONS: Shielding the pedicle screws intraoperatively using a guard provides a superior level of asepsis than currently practiced. All unshielded pedicles screws were carrying bioburden of virulent bacterial species, which provides an opportunity for the development of postoperative infections.

Quantitative Characteristics of Consecutive Lengthening Episodes in Early-onset Scoliosis (EOS) Patients With Dual Growth Rods.

STUDY DESIGN: A prospective single-center study. OBJECTIVE: The aim of this study was to record the characteristic forces and lengths observed during distraction episodes in early-onset scoliosis (EOS), and analyze their interdependencies on the key variability among the patients. SUMMARY OF BACKGROUND DATA: The goal of the growing-rod technique is to achieve deformity correction alongside maintaining growth of the spine. The deformity correction is achieved during the initial surgery, but follow-up distraction episodes are necessary to maintain the growth. The key variables, under the control of a surgeon, that affect the growth are the applied distraction forces and the distraction lengths. Since the advent of dual growth rod technique, there have been many studies exploring the relationship between these and the actual growth. However, there is sparse evidence on the actual magnitude of distraction forces, and none on its association with patient's parameters such as sex, age, and deformity. METHODS: In a consecutive series of 47 patients implanted with dual growth rods, the distraction forces (in N) and the lengths (in mm) achieved during each distraction episode and compared against the episode-specific demographics. The values obtained from each side, that is, concave and convex sides, were averaged to calculate the mean. Statistical analysis was performed using t-distribution because for each normalized time points (distraction episode). RESULTS: In cumulative, the distraction force increased by an amount of 268%, with 120% increase in the early stages (distractions episodes 1-6) and 68% increase in the later stages (distractions episodes 6-11), whereas the cumulative decrease in the length over 11 distractions episodes was 47%, with 34% and 20% in the early and later stages, respectively. The study does not identify any significant trend with respect to sex, age, and deformity. CONCLUSION: The distraction force and the length increased and decreased respectively with every consecutive distraction episode, with no correlation to sex, age, extent of deformity, or the extent of correction. LEVEL OF EVIDENCE: 5.

Optimal satellite rod constructs to mitigate rod failure following pedicle subtraction osteotomy (PSO): a finite element study.

BACKGROUND CONTEXT: Pedicle subtraction osteotomy (PSO) is a challenging restoration technique for sagittal imbalance and is associated with significant complications. One of the major complications is rod fracture and there exists a need for a biomechanical assessment of this complication for various instrumentation configurations. PURPOSE: To evaluate and compare the global range of motion (ROM), rod stress distribution, and the forces on the pedicle subtraction site in various instrumentation configurations using finite element analysis. STUDY DESIGN/SETTING: A computational biomechanical analysis. METHODS: A previously validated osseoligamentous three-dimensional spinopelvic finite element model (T10-pelvis) was used to develop a 30° PSO at the L3 level. In addition to the standard bilateral cobalt chromium primary rod instrumentation of the PSO model, various multirod configurations including constructs with medially, laterally, and posteriorly affixed satellite rods and the short-rod technique were assessed in spinal physiological motions. T10-S1 global ROM, maximum von Mises stress on the rods and at the PSO level, factor of safety (yield stress of the rod material/maximum actual stress in the rod) and the load acting across the PSO site were compared between various instrumentation configurations. The higher the factor of safety the lesser the chances of rod failure. RESULTS: Among all multirod constructs, posteriorly affixed satellite rod construct showed the greatest motion reduction compared to the standard bilateral rod configuration followed by medially and laterally affixed satellite rod constructs. Compared to the standard bilateral rod configuration, recessed short-rod technique resulted in 4% to 49% reduction in T10-S1 ROM recorded in extension and lateral bending motions, respectively, while the axial rotation motion increased by approximately 31%. Considering the maximum stress values on the rods, the recessed short-rod technique showed the greatest factor of safety (FOS = 4.1) followed by posteriorly (FOS = 3.9), medially (FOS = 3), laterally affixed satellite rod constructs (FOS = 2.8), and finally the standard bilateral rod construct (FOS = 2.7). By adding satellite rods, the maximum von Mises stress at the PSO level of the rods also reduced significantly and at this level resulted in the greatest FOS in the posteriorly affixed satellite rod construct. Compared to the standard bilateral rod construct, the load magnitude acting on the osteotomy site decreased by 11%, 16%, and 37% in the laterally, medially, and posteriorly affixed satellite rod constructs, respectively, and did not change with the short-rod technique. CONCLUSIONS: Adding satellite rods increases the rigidity of the construct, which results in an increase in the stability and the reduction of the global ROM. Additionally, having satellite rods reduces the stress on the primary rods at the PSO level and shifts the stresses from this PSO region to areas adjacent to the side-by-side connectors. The data suggest a significant benefit in supplementing medial over lateral satellite rods at the PSO by reducing stress on the primary rods. Except the recessed short-rod technique, all other multirod constructs decrease the magnitude of the load acting across the osteotomy region, which could cause a delayed or non-union at the PSO site. CLINICAL SIGNIFICANCE: The study evaluates the mechanical performance of various satellite rod instrumentation configurations following PSO to predict the risk factors for rod fracture and thereby mitigate the rate of clinically relevant failures.

Implant Prophylaxis: The Next Best Practice Toward Asepsis in Spine Surgery.

STUDY DESIGN: A literature review. OBJECTIVES: An evaluation of the contaminants prevalent on implants used for surgery and the aseptic methods being employed against them. METHODS: PubMed was searched for articles published between 2000 and 2017 for studies evaluating the contaminants present on spine implants, and associated pre- and intraoperative implant processing and handling methodology suggested to avoid them. Systematic reviews, observational studies, bench-top studies, and expert opinions were included. RESULTS: Eleven studies were identified whose major focus was the asepsis of implants to reduce the incidence of surgical site infection incidences during surgery. These studies measured the colony forming units of bacteria on sterilized implants and/or gloves from the surgeon, scrub nurse, and assistants, as well as reductions of surgical site infection rates in spine surgery due to changes in implant handling techniques. Additionally, the search included assessments of endotoxins and carbohydrates present on reprocessed implants. The suggested changes to surgical practice based on these studies included handling implants with only fresh gloves, keeping implants covered until the immediate time of use, reducing operating room traffic, avoiding reprocessing of implants (ie, providing terminally sterilized implants), and avoiding touching the implants altogether. CONCLUSIONS: Both reprocessing (preoperative) and handling (intraoperative) of implants seem to lead to contamination of sterilized implants. Using a terminally sterilized device may mitigate reprocessing (preoperative implant prophylaxis), whereas the use of fresh gloves for handling each implant and/or a permanent shielding technique (intraoperative implant prophylaxis) could potentially avoid recontamination at the theatre.

A Paradigm Shift Toward Terminally Sterilized Devices.

Given the complexity of the sterilization process, and the risk involved in absence of strict adherence to the protocol described by the medical device manufacturers, terminally sterilized devices are emerging and being promoted in the field of medical practices. The characteristics associated with conventional reprocessing are demanding logistics, costs of delay, operations and adverse events, and unacceptable liability. Demanding logistics were a result of decoupled staff between the operating room and sterilize processing department, understaffed and high-volume processing with an additional burden due to inventory management and inefficient training. Other costs arose from upkeep, delay in operating room, and surgical-site infections. Liability arose from the repeatedly use of an unquantifiable process thus adding uncertainties, limited shelf life of the reprocessed implants, contingency of flash sterilization and introduction of newer technology with higher demand on cleaning performances. In contrast, terminally sterilized single-use devices do not carry any of the aforementioned-characteristics, deeming it to be the simplest solution to the current conundrum. This review serves to provide an evaluation of logistics, costs, and potential adverse effects, both directly and indirectly, associated with current practices in the sterile processing department, and also describes as to how the use of terminally sterilized devices can help circumvent those.

Sex Specific Sacroiliac Joint Biomechanics During Standing Upright: A Finite Element Study.

STUDY DESIGN: The comparison of sacroiliac joint (SIJ) angular motions, pelvis ligaments strain, load sharing, and stress distribution across the joint for male and female spine-pelvis-femur models using finite element analysis. OBJECTIVE: To quantify biomechanical parameters at SIJ for all motions for both male and female models. SUMMARY OF BACKGROUND DATA: SIJ has been recognized as a main source of pain in 13% to 30% of patients with low back pain. It is shown that the SIJ rotation and translation in different planes are not exceeding 2° to 3° and 2 mm, respectively. Due to limitation of in vivo and in vitro studies, it is difficult to quantify certain biomechanical parameters such as load-sharing and stress distribution across the joint. Finite element analysis is a useful tool which can be utilized to understand the biomechanics of the SIJ. METHODS: The validated finite element models of a male and a female lumbar spine-pelvis-femur were developed from computer tomography (CT) scans. The models were used to simulate spine physiological motions. The range of motion, ligament strains, load sharing, and stress distribution across the left and right SIJs were compared between male and female models. RESULTS: Motions data at SIJs demonstrated that female model experienced 86% higher mobility in flexion, 264% in extension, 143% in left bending, and 228% in right bending compared with the male model. The stresses and loads on SIJs were higher on the female model compared with the male model. Female model ligaments underwent larger strains compared with the male model ligaments. CONCLUSION: Female SIJ had higher mobility, stresses, loads, and pelvis ligament strains compared with the male SIJ which led to higher stress across the joint, especially on the sacrum under identical loading conditions. This could be a possible reason for higher incidence of SIJ pain and pelvic stress fracture in females. LEVEL OF EVIDENCE: N/A.

Patient-specific Distraction Regimen to Avoid Growth-rod Failure.

STUDY DESIGN: A finite element study to establish the relationship between patient's curve flexibility (determined using curve correction under gravity) in juvenile idiopathic scoliosis and the required distraction frequency to avoid growth rod fracture, as a function of time. OBJECTIVE: To perform a parametric analysis using a juvenile scoliotic spine model (single mid-thoracic curve with the apex at the eighth thoracic vertebra) and establish the relationship between curve flexibility (determined using curve correction under gravity) and the distraction interval that allows a higher factor of safety for the growth rods. SUMMARY OF BACKGROUND DATA: Previous studies have shown that frequent distraction with smaller magnitude of distractions are less likely to result in rod failure. However there has not been any methodology or a chart provided to apply this knowledge on to the individual patients that undergo the treatment. This study aims to fill in that gap. METHOD: The parametric study was performed by varying the material properties of the disc, hence altering the axial stiffness of the scoliotic spine model. The stresses on the rod were found to increase with increased axial stiffness of the spine, and this resulted in the increase of required optimal frequency to achieve a factor of safety of two for growth rods. RESULTS: A relationship between the percentage correction in Cobb's angle due to gravity alone, and the required distraction interval for limiting the maximum von Mises stress to 255 MPa on the growth rods was established. The distraction interval required to limit the stresses to the selected nominal value reduces with increase in stiffness of the spine. Furthermore, the appropriate distraction interval reduces for each model as the spine becomes stiffer with time (autofusion). This points to the fact the optimal distraction frequency is a time-dependent variable that must be achieved to keep the maximum von Mises stress under the specified factor of safety. CONCLUSION: The current study demonstrates the possibility of translating fundamental information from finite element modeling to the clinical arena, for mitigating the occurrence of growth rod fracture, that is, establishing a relationship between optimal distraction interval and curve flexibility (determined using curve correction under gravity). LEVEL OF EVIDENCE: N/A.

Regulation of RANKL-induced osteoclastogenesis by RING finger protein RNF114.

Normal bone remodeling is a continuous process orchestrated by bone-resorbing osteoclasts and bone-forming osteoblasts, which an imbalance in bone remodeling results in metabolic bone diseases. RANKL, a member of the TNF cytokine family, functions as a key stimulator for osteoclast differentiation and maturation. Here, we report that RNF114, previously identified as a psoriasis susceptibility gene, plays a regulatory role in the RANKL/RANK/TRAF6 signaling pathway that mediates osteoclastogenesis. Our results demonstrated that RNF114 expression was significantly down-regulated in mouse osteoclast precursor cells undergoing RANKL-induced osteoclast differentiation. RNF114 knockout did not affect development or viability of the subpopulation of bone marrow macrophages capable of differentiating into osteoclasts in culture. However, in the presence of RANKL, RNF114 knockout bone marrow macrophages exhibited enhanced cell proliferation and augmented osteoclast differentiation, as shown by an increased expression of mature osteoclast markers, increased osteoclastic TRAP activity and bone resorption. Conversely, ectopic expression of RNF114 inhibited CTSK expression, TRAP activity, and bone resorption in RANKL-treated pre-osteoclasts. RNF114 also suppressed RANKL-activated NFATc1 expression and NFAT-regulated promoter activity. RNF114 suppressed TRAF6-, but not TAK1/TAB2-mediated NF-κB activation downstream of RANKL/RANK. In particular, TRAF6 protein levels were down-regulated by RNF114, possibly via K48-mediated proteasome-dependent degradation. These data suggested that RNF114's inhibitory effect on RANKL-stimulated osteoclastogenesis was mediated by blocking RANK/TRAF6/NF-κB signal transduction. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:159-166, 2018.

Practice makes perfect: relationship between hospital procedure volume and permanent pacemaker implantation after paroxysmal supraventricular tachycardia ablation.

PURPOSE: Paroxysmal supraventricular tachycardia (PSVT) ablation can result in injury to the atrioventricular (AV) node causing complete heart block requiring permanent pacemaker (PPM) implantation. Few studies have examined the impact of hospital PSVT ablation volume and PPM implantation rates post ablation. METHODS: We included adult patients from the Nationwide Inpatient Sample (NIS) database, from 1998 to 2011, using ICD-9 diagnoses codes 427.0 and 427.89 for PSVT and ICD-9 procedure code 37.34 for ablation. Patients with concomitant arrhythmias, prior pacemaker/defibrillator implants, or pre-existing sinus node dysfunction were excluded. Multivariate logistic regression analysis was performed to identify predictors of PPM implantation. RESULTS: There were 119,938 PSVT ablations from 1998 to 2011 with a mean age of 54.6 ± 17.5 years and 64.1% females. The overall PPM implantation rate was 3.2%. PPM implantation rates in the first (1-14 ablations/year), second (15-32 ablations/year), and third (> 32/ablations/year) tertiles of annual PSVT ablation volume were respectively 4.4, 3.3, and 1.9% (p < 0.001). Increasing age, female gender, bifascicular, or trifascicular block and teaching hospital status were independent predictors of PPM implantation. The adjusted odds ratio for PPM implantation in hospitals performing > 32 PSVT ablations/year compared to hospitals performing ≤ 14 PSVT ablations/year was 0.54 (95% confidence interval 0.3-0.9, p = 0.026). CONCLUSIONS: PPM implantation rates are significantly lower in hospitals performing > 32 PSVT ablations/year, indicating that hospital experience is an important determinant of outcomes after PSVT ablation.

Evaluation of Apical Vapor Lock Formation and comparative Evaluation of its Elimination using Three different Techniques: An in vitro Study.

AIM: The aim of this study was (i) to evaluate the formation of air bubbles in the apical region of root canal (apical vapor lock) during syringe irrigation, using cone beam computed tomography (CBCT) and (ii) comparative evaluation of the elimination of an established vapor lock by EndoActivator, ultrasonics, and manual dynamic agitation (MDA), using CBCT. MATERIALS AND METHODS: A total of 60 extracted human single-rooted teeth were equally divided into three groups of 20 teeth each. The samples were decoronated 17 mm from the apex, cleaned, and shaped to size F4 Protaper using 3% sodium hypochlorite. Samples were irrigated with 3% sodium hypochlorite + cesium chloride radiopaque dye, and preoperative CBCT images were obtained. After formation of apical vapor lock in the scanned teeth, EndoActivator (group I), passive ultrasonic irrigation (group II), and MDA with K-file (group III) were performed and the teeth were again placed in CBCT scanner and results analyzed using the chi-square test. RESULTS: The apical vapor lock was formed in all the samples. Out of the 20 teeth in each group, the apical vapor lock was eliminated in 18 samples of EndoActivator group (90%), 16 samples of ultrasonic group (80%), while it was eliminated in 10 samples by MDA (50%). CONCLUSION: It is concluded that (1) apical vapor lock is consistently formed during endodontic irrigation in closed canal systems and (2) sonic activation performs better than the ultrasonics and MDA in eliminating the apical vapor lock, with statistically significant difference between all the three groups (p < 0.05). CLINICAL SIGNIFICANCE: The results suggest that the apical vapor lock (dead water zone) is consistently formed during routine endodontic irrigation which impedes irrigant penetration till the working length, thereby leading to inefficient debridement. Hence, to eliminate this vapor lock, techniques, such as sonics or ultrasonics should be used along with the irrigant after shaping and cleaning of the root canal.