Differential DNA methylation associated with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage: a systematic review.

Recent studies suggest that differential DNA methylation could play a role in the mechanism of cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Considering the significance of this matter and a lack of effective prophylaxis against DCI, we aim to summarize the current state of knowledge regarding their associations with DNA methylation and identify the gaps for a future trial. PubMed MEDLINE, Scopus, and Web of Science were searched by two authors in three waves for relevant DNA methylation association studies in DCI after aSAH. PRISMA checklist was followed for a systematic structure. STROBE statement was used to assess the quality and risk of bias within studies. This research was funded by the National Science Centre, Poland (grant number 2021/41/N/NZ2/00844). Of 70 records, 7 peer-reviewed articles met the eligibility criteria. Five studies used a candidate gene approach, three were epigenome-wide association studies (EWAS), one utilized bioinformatics of the previous EWAS, with two studies using more than one approach. Methylation status of four cytosine-guanine dinucleotides (CpGs) related to four distinct genes (ITPR3, HAMP, INSR, CDHR5) have been found significantly or suggestively associated with DCI after aSAH. Analysis of epigenetic clocks yielded significant association of lower age acceleration with radiological CVS but not with DCI. Hub genes for hypermethylation (VHL, KIF3A, KIFAP3, RACGAP1, OPRM1) and hypomethylation (ALB, IL5) in DCI have been indicated through bioinformatics analysis. As none of the CpGs overlapped across the studies, meta-analysis was not applicable. The identified methylation sites might potentially serve as a biomarker for early diagnosis of DCI after aSAH in future. However, a lack of overlapping results prompts the need for large-scale multicenter studies. Challenges and prospects are discussed.

Aluminum Nanoparticles Affect Human Platelet Function In Vitro.

Endoprostheses are prone to tribological wear and biological processes that lead to the release of particles, including aluminum nanoparticles (Al NPs). Those particles can diffuse into circulation. However, the toxic effects of NPs on platelets have not been comprehensively analyzed. The aim of our work was to investigate the impact of Al NPs on human platelet function using a novel quartz crystal microbalance with dissipation (QCM-D) methodology. Moreover, a suite of assays, including light transmission aggregometry, flow cytometry, optical microscopy and transmission electron microscopy, were utilized. All Al NPs caused a significant increase in dissipation (D) and frequency (F), indicating platelet aggregation even at the lowest tested concentration (0.5 µg/mL), except for the largest (80 nm) Al NPs. A size-dependent effect on platelet aggregation was observed for the 5-20 nm NPs and the 30-50 nm NPs, with the larger Al NPs causing smaller increases in D and F; however, this was not observed for the 20-30 nm NPs. In conclusion, our study showed that small (5-50 nm) Al NPs caused platelet aggregation, and larger (80 nm) caused a bridging-penetrating effect in entering platelets, resulting in the formation of heterologous platelet-Al NPs structures. Therefore, physicians should consider monitoring NP serum levels and platelet activation indices in patients with orthopedic implants.

Genome-wide association mapping of ethanol sensitivity in the Diversity Outbred mouse population.

BACKGROUND: A strong predictor for the development of alcohol use disorder (AUD) is altered sensitivity to the intoxicating effects of alcohol. Individual differences in the initial sensitivity to alcohol are controlled in part by genetic factors. Mice offer a powerful tool to elucidate the genetic basis of behavioral and physiological traits relevant to AUD, but conventional experimental crosses have only been able to identify large chromosomal regions rather than specific genes. Genetically diverse, highly recombinant mouse populations make it possible to observe a wider range of phenotypic variation, offer greater mapping precision, and thus increase the potential for efficient gene identification. METHODS: We have taken advantage of the Diversity Outbred (DO) mouse population to identify and precisely map quantitative trait loci (QTL) associated with ethanol sensitivity. We phenotyped 798 male J:DO mice for three measures of ethanol sensitivity: ataxia, hypothermia, and loss of the righting response. We used high-density MegaMUGA and GigaMUGA to obtain genotypes ranging from 77,808 to 143,259 SNPs. We also performed RNA sequencing in striatum to map expression QTLs and identify gene expression-trait correlations. We then applied a systems genetic strategy to identify narrow QTLs and construct the network of correlations that exists between DNA sequence, gene expression values, and ethanol-related phenotypes to prioritize our list of positional candidate genes. RESULTS: We observed large amounts of phenotypic variation with the DO population and identified suggestive and significant QTLs associated with ethanol sensitivity on chromosomes 1, 2, and 16. The implicated regions were narrow (4.5-6.9 Mb in size) and each QTL explained ~4-5% of the variance. CONCLUSIONS: Our results can be used to identify alleles that contribute to AUD in humans, elucidate causative biological mechanisms, or assist in the development of novel therapeutic interventions.

Vitamin D receptor gene polymorphism influence on lumbar intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration is a multifaceted pathology that is the main morphological cause of lower back pain. This study aimed to determine the link between the vitamin D receptor gene single nucleotide polymorphisms (SNPs) and degenerative processes of the lumbar spine. The complete lumbar spinal columns were collected from 100 Caucasian cadavers via ventral dissection. The specimens for the histological analysis were harvested from the L5/S1 IVDs and endplates. Then, the tissues were cut into slices, inserted into paraffin blocks, and stained. The histology was evaluated according to the Boos' protocol. Moreover, TaqI(rs731236), FokI(rs2228570), and ApaI(rs7975232) genotyping were performed. Lastly, the histological scores for different genotypes were analyzed. The overall Boos' score in the study group was 12.49. It consisted of a mean IVD score of 7.46 and endplate score of 5.39. The determination of the SNPs was successful in 99 specimens and had a distribution of all alleles in accordance with the Hardy-Weinberg equilibrium. No significant differences in overall histological degeneration scores were found between samples from donors with different genotypes. However, in subgroup analysis of specific regions on the IVD, the significant difference was found in posterior inner anulus fibrosus for ApaI. The results of this study suggest that one must be careful when interpreting the results of the clinical and/or radiological studies on vitamin D receptor gene polymorphisms and lumbar spine degeneration risk, because such a relationship, if present, is likely to be very subtle.

In vitro effects of cobalt and chromium nanoparticles on human platelet function.

Nanoparticles (NPs) are released from orthopedic and neurosurgical prostheses and can interact with a number of blood components once in the bloodstream. Potential toxic effects of Co and Cr NPs on blood platelets have not been thoroughly investigated. The aim of this study was to analyze the effect of Co and Cr NPs on platelet function in vitro. The ability of the tested NPs to induce platelet activation and aggregation was measured using light transmission aggregometry, flow cytometry, and quartz crystal balance with dissipation (QCM-D). This was confirmed by transmission electron microscopy (TEM), scanning electron microscopy, and optical and immunofluorescence microscopy. Perfusion of QCM-D sensor crystals with platelet-rich-plasma in the presence of Co 28 nm, CoO 50 nm, Co2O3 50 nm, Co3O4 30-50nm, Cr 35-45nm, Cr2O3 60 nm NPs (0.5-5.0 µg/mL) resulted in significant changes in frequency and dissipation, indicating that these NPs caused platelet microaggregation. Transmission electron microscopy also revealed that Cr NPs led to platelet swelling and lysis. Our study shows that both Co and Cr NPs affect platelet function in vitro with two distinct mechanisms. While Co NPs result in standard platelet aggregation, Cr NPs cause both platelet aggregation and decreased platelet membrane integrity and lysis. Based on these findings, monitoring serum NP levels and platelet-mediated hemostasis can be advised in patients with metal-on-metal Co-Cr prostheses.

Artery of Adamkiewicz: a meta-analysis of anatomical characteristics.

PURPOSE: The artery of Adamkiewicz (AKA) provides the major blood supply to the anterior thoracolumbar spinal cord and iatrogenic injury or inadequate reconstruction of this vessel during vascular and endovascular surgery can result in postoperative neurological deficit due to spinal cord ischemia. The aim of this study was to provide comprehensive data on the prevalence and anatomical characteristics of the AKA. METHODS: An extensive search was conducted through the major electronic databases to identify eligible articles. Data extracted included study type, prevalence of the AKA, gender, number of AKA per patient, laterality, origin based on vertebral level, side of origin, morphometric data, and ethnicity subgroups. RESULTS: A total of 60 studies (n = 5437 subjects) were included in the meta-analysis. Our main findings revealed that the AKA was present in 84.6% of the population, and patients most frequently had a single AKA (87.4%) on the left side (76.6%) originating between T8 and L1 (89%). CONCLUSION: As an AKA is present in the majority of the population, caution should be taken during vascular and endovascular surgical procedures to avoid injury or ensure proper reconstruction. All surgeons operating in the thoracolumbar spinal cord should have a thorough understanding of the anatomical characteristics and surgical implications of an AKA.

The prevalence and anatomy of parathyroid glands: a meta-analysis with implications for parathyroid surgery.

PURPOSE: The anatomy of parathyroid glands (PTG) is highly variable in the population. The aim of this study was to conduct a systematic analysis on the prevalence and location of PTG in healthy and hyperparathyroidism (HPT) patients. METHODS: An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the number of PTG per patient and location of PTG. The data was extracted from the eligible studies and pooled into a meta-analysis. RESULTS: The overall analysis of 26 studies (n = 7005 patients; n = 23,519 PTG) on the number of PTG showed that 81.4% (95% CI 65.4-85.8) of patients have four PTG. A total of 15.9% of PTG are present in ectopic locations, with 11.6% (95% CI 5.1-19.1) in the neck and 4.3% (95% CI 0.7-9.9) in mediastinum. The subgroup analysis of ectopic PTG showed that 51.7% of ectopic PTG in the neck are localized in retroesophageal/paraesophageal space or in the thyroid gland. No significant differences were observed between the healthy and HPT patients and cadaveric and intraoperative studies. CONCLUSIONS: Knowledge regarding the prevalence, location, and anatomy of PTG is essential for surgeons planning for and carrying out parathyroidectomies, as any unidentified PTG, either supernumerary or in ectopic location, can result in unsuccessful treatment and need for reoperation.

Prevalence and anatomy of the axillary arch and its implications in surgical practice: A meta-analysis.

PURPOSE: The following research aimed to investigate the prevalence and anatomical features of the axillary arch (AA) - a muscular, tendinous or musculotendinous slip arising from the latissimus dorsi and that terminates in various structures around the shoulder girdle. The AA may complicate axillary lymph node biopsy or breast reconstruction surgery and may cause thoracic outlet syndrome. METHODS: Major electronic databases were thoroughly searched for studies on the AA and its variations. Data regarding the prevalence, morphology, laterality, origin, insertion and innervation of the AA was extracted and included in this meta-analysis. The AQUA tool was used in order to assess potential risk of bias within the included studies. RESULTS: The AA was reported in 29 studies (10,222 axillas), and its pooled prevalence estimate in this meta-analysis was found to be 5.3% of the axillas: unilaterally (61.6%) and bilaterally (38.4%). It was predominantly muscular (55.1% of the patients with the AA), originated from the latissimus dorsi muscle or tendon (87.3% of the patients with the AA), inserted into the pectoralis major muscle or fascia (35.2% of the patients with the AA), and was most commonly innervated by the thoracodorsal nerve (39.9% of the patients with the AA). CONCLUSION: The AA is a relatively common variant, hence it should not be neglected. Oncologists and surgeons should consider this variant while diagnosing an unknown palpable mass in the axilla, as the arch might mimic a neoplasm or enlarged lymph nodes.

Incidence, Risk Factors, and Comorbidities of Vocal Cord Paralysis After Surgical Closure of a Patent Ductus Arteriosus: A Meta-analysis.

Surgical closure of a patent ductus arteriosus (PDA) is considered standard treatment for symptomatic neonates refractory to medical therapy. Sometimes, iatrogenic injury to the left recurrent laryngeal nerve during the procedure can result in vocal cord paralysis (VCP). This study aimed to estimate the incidence of VCP in patients after surgical PDA closure and to identify any associated risk factors and morbidities associated with VCP in the preterm infant population. A thorough search of the major electronic databases was conducted to identify studies eligible for inclusion into this meta-analysis. Studies reporting data on the incidence of VCP (primary outcomes) or risk factors and morbidities associated with VCP in premature infant population (secondary outcomes) were included. A total of 33 studies (n = 4887 patients) were included into the analysis. Overall pooled incidence estimate of VCP was 7.9% (95%CI 5.3-10.9). The incidence of VCP after PDA closure was significantly much higher in premature infants (11.2% [95%CI 7.0-16.3]) than in non-premature patients (3.0% [95%CI 1.5-4.9]). The data showed that VCP was most common after surgical ligation and in studies conducting universal laryngoscopy scoping. The risk factors for postoperative VCP in preterm infants included birth weight and gestational age. In addition, VCP was significantly associated with the occurrence of bronchopulmonary dysplasia, gastrostomy tube insertion, and increased duration of mechanical ventilation. Vocal cord paralysis remains a frequent complication of surgical closure of a PDA, especially in premature neonates, and is associated with significant post-procedural complications.

FokI as a genetic factor of intervertebral disc degeneration: A PRISMA-compliant systematic review of overlapping meta-analyses.

The association of FokI (rs2228570), a polymorphism of the vitamin D receptor gene, with intervertebral disc degeneration (IDD) has been investigated in a multitude of studies. However, conflicting results of these studies led to emergence of several meta-analyses over the past few years. Despite the increased statistical power, these meta-analyses have failed to provide uniform and conclusive data on the relationship of FokI with IDD. The aim of this study was to present a comprehensive review based on the most up-to-date meta-analyses on the association of FokI with IDD. A comprehensive search of all major databases was conducted to identify meta-analyses investigating relation between FokI and IDD. No date or language restrictions were applied. The Jadad decision algorithm was utilized to evaluate included meta-analyses and identify the one providing the best evidence. A total of 7 meta-analyses (n = 2580 original patients), that included six to ten case control studies, analyzed the association of FokI polymorphism with IDD. The meta-analysis of the highest quality supported the notion that overall there is no statistically significant association between FokI polymorphism and IDD. However, the authors showed that Caucasians have a reduced risk of IDD and Hispanics have an increased risk of IDD in the dominant and dominant/homozygous/heterozygous models of FokI polymorphism. While currently there is no evidence of an association between FokI polymorphism and IDD in the general population, ethnic predisposition has been shown.

Presence of a foramen arcuale as a possible cause for headaches and migraine: Systematic review and meta-analysis.

The foramen arcuale (FA) is an osseous bridge that can be formed on the posterior arch of the atlas, often observed on lateral radiographs of the cervical spine. Currently, there is a lack of studies that systematically review the available literature on the FA and its role in headaches and migraines. Therefore, we conducted an extensive search of the major electronic databases to identify all studies that reported relevant data on patients with versus without FA and prevalence of headaches or migraines. No date or language restrictions were applied. Data on the prevalence, type (complete and incomplete), and laterality of the FA and relationship with headaches or migraines were extracted and pooled into a meta-analysis. There were 168/412 (40.8%) patients with headaches in the FA group compared to 368/1691 (21.8%) patients with headaches in the no FA group (OR 4.68; P = 0.002). The proportion of headaches for complete FA was 73/125 (58.4%) compared with 80/413 (19.4%) for incomplete FA (OR 5.04; P = 0.04). When comparing incomplete FA to no FA, the proportion of headaches was 36/85 (42.3%) vs 65/560 (11.6%), and this was significantly different (OR 6.13; P = 0.009). The proportion of headaches in patients with bilateral FA was 67/132 (50.8%) compared to 80/140 (57.1%) in the unilateral group (OR 1.36; P = 0.72). We performed the first meta-analysis to demonstrate the significant association between FA and headaches, and provided further support for the notion of the clinical relevance of this anatomical variant.

Genome-wide association for testis weight in the diversity outbred mouse population.

Testis weight is a genetically mediated trait associated with reproductive efficiency across numerous species. We sought to evaluate the genetically diverse, highly recombinant Diversity Outbred (DO) mouse population as a tool to identify and map quantitative trait loci (QTLs) associated with testis weight. Testis weights were recorded for 502 male DO mice and the mice were genotyped on the GIGAMuga array at ~ 143,000 SNPs. We performed a genome-wide association analysis and identified one significant and two suggestive QTLs associated with testis weight. Using bioinformatic approaches, we developed a list of candidate genes and identified those with known roles in testicular size and development. Candidates of particular interest include the RNA demethylase gene Alkbh5, the cyclin-dependent kinase inhibitor gene Cdkn2c, the dynein axonemal heavy chain gene Dnah11, the phospholipase D gene Pld6, the trans-acting transcription factor gene Sp4, and the spermatogenesis-associated gene Spata6, each of which has a human ortholog. Our results demonstrate the utility of DO mice in high-resolution genetic mapping of complex traits, enabling us to identify developmentally important genes in adult mice. Understanding how genetic variation in these genes influence testis weight could aid in the understanding of mechanisms of mammalian reproductive function.

Cervical Rib Prevalence and its Association with Thoracic Outlet Syndrome: A Meta-Analysis of 141 Studies with Surgical Considerations.

BACKGROUND: Cervical ribs (CR) are supernumerary ribs that arise from the seventh cervical vertebra. In the presence of CR, the boundaries of the interscalene triangle can be further constricted and result in neurovascular compression and thoracic outlet syndrome (TOS). The aim of our study was to provide a comprehensive evidence-based assessment of CR prevalence and their association with TOS as well as surgical approach to excision of CR and surgical patients' characteristics. METHODS: A thorough search of major electronic databases was conducted to identify any relevant studies. Data on the prevalence, laterality, and side of CR were extracted from the eligible studies for both healthy individuals and patients with TOS. Data on the type of TOS and surgical approach to excision of CR were extracted as well. RESULTS: A total of 141 studies (n = 77,924 participants) were included into the meta-analysis. CR was significantly more prevalent in patients with TOS than in healthy individuals, with pooled prevalence estimates of 29.5% and 1.1%, respectively. More than half of the patients had unilateral CR in both the healthy and the TOS group. The analysis showed that 51.3% of the symptomatic patients with CR had vascular TOS, and 48.7% had neurogenic TOS. Most CR were surgically excised in women using a supraclavicular approach. CONCLUSIONS: CR ribs are frequent findings in patients with TOS. We recommended counseling asymptomatic patients with incidentally discovered CR on the symptoms of TOS, so that if symptoms develop, the patients can undergo prompt and appropriate workup and treatment.

Radiological results and clinical complications after calcaneal articular fracture surgical treatment using minimally invasive percutaneous fixation.

The choice of method for surgical treatment of articular calcaneal fractures remains problematic due to the potential complications and difficulty in restoring loss of functional status, anatomical geometry and congruence of joint surfaces. The preferred method of surgical treatment for these injuries, among others, is still minimally invasive percutaneous fixation. The aim of this study was to evaluate the radiological results of articular calcaneal fractures surgical treatment using a minimally invasive percutaneous fixation and to determine the prevalence of complications in early and long-term observation. Radiological results of surgical treatment of 82 patients operated using minimally invasive percutaneous fixation were analyzed. The radiological results were based on Bohler angle and varus angle using criteria according to Harnroongroj and Golec. Postoperative complications were registered in a 3 months follow-up (early observation) and after 6 months (long-term observation). Patients with tongue-type fractures had significantly better surgical outcomes than patients with depression-type fractures. Displacements of bone fragments in articular calcaneal fractures visualized radiographically by the changes of Harnroongroj et al. angle do not constitute a serious surgical problem and are easily repositioned and stabilized, as opposed to displacements resulting in changes in the value of the Böhler angle. The most common postoperative complications were local inflammatory reactions at the point of entry of fixation material and thromboembolic complications. Results of surgical treatment of articular fractures of the calcaneus using a minimally invasive percutaneous fixation are good and satisfactory in majority of patients suggesting that this method constitutes proper choice of treatment.

Polish translation of the Anatomical Quality Assurance (AQUA) Checklist: new guidelines for reporting in original anatomical studies.

Recently, an improvement of the quality of reporting and methodology in original research has been observed. Major fields in research have introduced checklists aimed at promoting clear and univocal reporting of methods and results. The basis of evidence-based medicine (EBM) lies in transparent reporting of primary studies. Although clinical research progressed rapidly into evidence-based guidelines, the basic sciences, including anatomy, just recently started to use the rules of EBM. No anatomy-specific standardized research checklist has been introduced so far. Evidence-based anatomy (EBA) emerged as a new approach to research in anatomy that incorporates methods, such as meta-analysis and systematic review. High quality methodology and clear reporting of results of original studies are the basis of EBA. The Anatomical Quality Assurance (AQUA) Checklist is a new tool aimed to introduce univocal reporting of original anatomical studies. The checklist consists of 29 reporting items, which are essential in obtaining unambiguous and high-quality reporting of methods and results and ensuing straightforward interpretation and reproducibility. The AQUA Checklists been endorsed by anatomical associations, including the International Federation of Associations of Anatomists. Therefore, the authors of this study believe that introduction of the Polish version of AQUA Checklist into practice will improve the quality of original anatomical studies in Poland and will promote the EBA standards for years to come.

The pterygoalar bar: A meta-analysis of its prevalence, morphology and morphometry.

PURPOSE: The pterygoalar (PA) bar is a bony bridge resulting from the partial or complete ossification of a PA ligament. The aim of this meta-analysis was to systematically analyze and provide the most comprehensive data on the prevalence, morphology and topographical anatomy of the PA bar. MATERIALS AND METHODS: A comprehensive search of the major electronic databases (PubMed, Embase, ScienceDirect, SciELO, BIOSIS, and Web of Science) was conducted in order to identify relevant studies. Studies reporting the prevalence, side of occurrence, gender dimorphism and morphometry of the PA bar were included in the current study. RESULTS: A total of 25 articles (n = 16,168 subjects) were included in the meta-analysis. The overall pooled prevalence of the complete PA bar was 4.4% (95% CI: 3.0-6.0) and of the incomplete was 8.4% (95% CI: 4.6-13.3). The PA bar was most often observed unilaterally, on the left side. Analysis of geographical subgroups revealed considerable differences, with the lowest prevalence rates in Europe for both incomplete and complete PA bars. CONCLUSIONS: Considering the prevalence and anatomical characteristics of the PA bar, caution is recommended while planning or performing transfacial needle approach to the foramen ovale and when considering a differential diagnosis for nerve compression or entrapment syndromes.

The prevalence and morphometry of an accessory spleen: A meta-analysis and systematic review of 22,487 patients.

BACKGROUND: An accessory spleen (AS) is a lobule of splenic tissue found in ectopic locations. Identification of AS is particularly important in patients with immune thrombocytopenia (ITP) requiring splenectomy as unrecognized AS can later cause refractory symptoms. The AS can also be a source of significant intraabdominal hemorrhage. The aim of this meta-analysis was to systematically analyze the data on the prevalence, number, location, and morphometry of AS. MATERIALS AND METHODS: An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the AS. No date or language restrictions were applied. Data on the study type, the prevalence of AS, location, morphometry and number of AS per patient were extracted from the eligible studies and pooled into a meta-analysis. RESULTS: A total of 81 studies (n = 22,487 subjects) were included into the quantitative analysis. The overall pooled prevalence of AS was 14.5% (95%CI: 12.4-16.7), while the pooled prevalence of AS in ITP patients was 16.7% (95%CI: 12.1-21.7). The majority of accessory spleens were located in the splenic hilum (62.1% [95%CI:51.5-76.3]). Moreover, 26% of ITP patients with an AS have more than one. CONCLUSIONS: The findings of this study provide an evidence-based foundation of anatomical knowledge about the AS. Surgeons should take particular caution in identifying an AS, as unnoticed AS during splenectomy can lead to recurrence of hematological diseases or can be a potential source of bleeding in the future.

Lateral and posterolateral foraminal variations of the atlas: A meta-analysis.

The lateral (LF) and posterolateral (PLF) foramina are anatomical variants of the atlas. Both variants have been implicated in multiple neurological conditions including vertebrobasilar insufficiency, with symptoms such as dizziness, syncope, auditory and visual disturbances and paresis. The aim of this study was to conduct a systematic meta-analysis on the prevalence and anatomical characteristics of the LF and PLF. An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the LF and PLF. No date or language restrictions were applied. Data on the prevalence, type (complete and incomplete), side, gender, and laterality of the LF and PLF, when available, were extracted and pooled into a meta-analysis. A total of 33 studies (n=10,190 subjects) were included in the quantitative analysis. The overall pooled prevalences of complete LF and PLF were 2.6% (95%CI: 2.1-3.1) and 1.2% (95%CI:0.6-2.0), respectively, while the overall pooled prevalence of the incomplete LF was 2.7% (95%CI:1.3-4.4) and the incomplete PLF was 0.7% (95%CI:0.0-1.8). When there was a complete PLF, a contralateral PLF (complete or incomplete) was found in 32.8% of cases. The geographical distribution of both variants was variable. The findings of this study provide an evidence-based foundation of anatomical knowledge of the two variants of the atlas. We recommend that physicians consider the possible role of the LF and PLF during the diagnosis of various neurological disturbances, especially in situations when all other possible explanations for the symptoms have been excluded.

The Variable Emergence of the Infrapatellar Branch of the Saphenous Nerve.

The infrapatellar branch of the saphenous nerve (IPBSN) is a cutaneous nerve of the lower limb, which arises distal to the adductor canal. High variability in the emergence, course, branching, termination, and morphometrics of the IPBSN poses an increased risk of injury to the nerve during surgical interventions on the anteromedial aspect of the knee. The aim of this study was to describe the anatomical characteristics of the IPBSN. This study utilized cadaveric (n = 100) and ultrasonography (n = 30) assessments, and meta-analysis. In the cadaveric study, the presence of IPBSN and its emergence mode in relation to the sartorius muscle (SaM) was determined (type A-anterior; type B-posterior; type C-penetrating the SaM). Ultrasonography examinations were conducted on healthy volunteers to determine the presence and mode of the emergence of the nerve. Finally, from electronic databases searching, all studies reporting the IPBSN emergence data were pooled into a meta-analysis. The mean distance between the medial border of the patellar ligament (MBPL) and the IPBSN at the level of the patellar apex (PA) was also analyzed in the cadaveric, ultrasonography, and meta-analysis portions of the study. Six studies (n = 336 limbs), including the present cadaveric study, were pooled into the meta-analysis of emergence. The most prevalent IPBSN emergence mode was type C (42.9%) followed by type B (41.9%) and type A (15.4%). In the ultrasonography assessment, type A was found to be the most common (82.8%). The mean distance between the MBPL and the IPBSN at the level of the PA was 4.89 ± 0.22 cm, and 5.57 ± 0.91 cm, for the cadaveric and meta-analysis studies combined, and the ultrasonography assessment, respectively. This multimodality study shows that the most common type of IPBSN emergence is type C. The horizontal distance between the MBPL and the IPBSN at the level of the PA is usually between 4.5 and 5.6 cm. Understanding the anatomy of IPBSN emergence is crucial for orthopedic surgeons to minimize the risks of iatrogenic nerve injury during surgical procedures in the region.