The anatomy of the nasal cavities and paranasal sinuses is one of the most varied in the human body. The aim of this study is to review the prevalence of anatomical variations in the sinonasal area. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We performed on PubMed a literature search from October 2004 until May 2020. The search strategy included the following keywords: (‘paranasal sinus’ OR ‘frontal sinus’ OR ‘maxillary sinus’ AND (‘anatomical variants’ OR ‘anomalies’)). Fifty studies were eligible and included in the analysis. Overall, the studies encompassed a total of 18,118 patients included in this review. Most common anatomical variations include agger nasi cells, nasal septum deviation and concha bullosa. Other variations seen in this region are uncinate process variations, paradoxical middle turbinate, Haller, Onodi and supraorbital ethmoid cells, accessory ostia of maxillary sinus. Less common variations include any sinus aplasia, crista galli pneumatization and dehiscence of the optic or maxillary nerve, internal carotid artery and lamina papyracea. Anatomical variations of this region also differ among ethnic groups. This study highlights the amount, variability and significance of most anatomical variants reported in the literature in the last years. It is essential for the sinus surgeon to have a broad spectrum of knowledge not only of “the typical” anatomy but also all the possible anatomical variations. With modern imaging modalities, anatomical variations can be detected, and uneventful pitfalls might be prevented.

Porous tantalum is a biomaterial that was recently introduced in orthopedics in order to overcome problems related to implant loosening. It is found to have osteoconductive, and possibly, osteoinductive properties hence useful in difficult cases with severe bone defects. So, it is of great interest to shed light on the mechanisms through which this material leads to new bone formation, after being implanted. Porous tantalum is biologically relatively inert, with restricted bonding capacity to the bone is restricted. In order to overcome this obstacle, it undergoes thermal processing in an alkaline environment. This process leads to extensive hydroxyapatite formation on its surface, and thus, to better integration of porous tantalum implants. Apart from this, new bone tissue formation occurs inside the pores of the porous tantalum after its implantation and this new bone retains the characteristics of the normal bone, that is, bone remodeling and Haversian systems formation. This finding is enhanced by the observation that porous tantalum is an appropriate substrate for osteoblast adherence, proliferation, and differentiation. Furthermore, the finding that osteoblasts derived from old women (> 60 years old) and cultivated on porous tantalum may grow faster than osteoblasts taken from younger women (< 45 years old) and cultivated on other substrates, can partially explain porous tantalum's good performance in cases of patients with severe bone defects. In conclusion, porous tantalum's chemical and mechanical properties are those that probably define the already noticed good performance of this material. However, further research is needed to totally clarify the mechanisms.

Between November 1997 and December 2000 we performed 27 total hip replacements in 22 patients with high congenital dislocation of the hip using porous tantalum monoblock acetabular components implanted in the true acetabular bed. Clinical and radiological evaluation was performed at regular intervals for a mean of 10.2 years (8.5 to 12). The mean Harris Hip Score improved from 48.3 (15 to 65) pre-operatively to 89.5 (56 to 100) at the final follow-up. The mean Oxford Hip Score was 49.5 (35 to 59) pre-operatively and decreased to 21.2 (12 to 48) at one year and 15.2 (10 to 28) at final follow-up. Migration of the acetabular component was assessed with the EBRA software system. There was a mean migration of 0.68 mm (0.49 to 0.8) in the first year and a mean 0.89 mm (0.6 to 0.98) in the second year, after excluding one initial excessive migration. No revision was necessary for any reason, no acetabular component became loose, and no radiolucent lines were observed at the final follow-up. The porous tantalum monoblock acetabular component is an implant offering adequate initial stability in conjunction with a modulus of elasticity and porosity close to that of cancellous bone. It favours bone ingrowth, leading to good mid-term results.

The accessory renal arteries (ARAs) are a well‐described variant of the renal vasculature with clinical implications for radiologists, surgeons, and clinicians. The aim of the present systematic review with meta‐analysis was to estimate the pooled prevalence of ARAs, including their variant number, origin, and termination, and to highlight symmetrical and asymmetrical morphological patterns. The systematic review used four online databases in accordance with PRISMA 2020 and Evidence‐based Anatomy Workgroup guidelines. R programming software was used for the statistical meta‐analysis. A total of 111 studies were considered eligible for our initial aim. The typical renal artery (RA) anatomy (a single bilateral vessel) was identified in 78.92%; the overall ARA prevalence was estimated at a pooled prevalence of 21.10%. The estimated pooled prevalence of one, two, three, and four ARAs were 18.67%, 1.80%, 0.01%, and <0.01%. The ARAs have been the subject of extensive research owing to their clinical importance, including in kidney transplantation surgery and resistant hypertension therapy. Knowledge of the typical and variant anatomy of RAs is essential for anatomists, radiologists, surgeons, and clinicians in order to avoid misunderstanding, complications, and iatrogenic injury.

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery’s hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Uterine arteries are the main vessels supplying blood to the uterus. Mainly, they originate from the anterior trunk of the internal iliac artery. Uterine arteries play an important role in pregnancy as well as transcatheter arterial embolization for postpartum hemorrhage and uterine fibroid management. This is a review of the English literature in the PubMed database of the anatomic variety on the origin of uterine arteries and their clinical significance. Eleven studies describe the origin of the uterine arteries and their variations in the literature. In six studies, the uterine artery emerged from internal iliac artery in the majority of the cases, either as a separate branch, or as a bifurcation with the inferior gluteal artery, or trifurcation with superior and inferior gluteal artery. In two studies, the inferior gluteal artery manifested as the main source of the uterine artery, whereas in three studies, the umbilical artery posed as its main origin. Internal iliac artery is described as the most common vascular origin of uterine artery. However, this review highlights that the main vessels of origin for uterine arteries are internal iliac, umbilical and inferior gluteal artery. Nevertheless, classification and further research for this peculiar anatomic structure is fundamental in the future.