Bone is a richly vascularized connective tissue. As the main source of oxygen, nutrients, hormones, neurotransmitters and growth factors delivered to the bone cells, vasculature is indispensable for appropriate bone development, regeneration and remodeling. Bone vasculature also orchestrates the process of hematopoiesis. Blood supply to the skeletal system is provided by the networks of arteries and arterioles, having distinct molecular characteristics and localizations within the bone structures. Blood vessels of the bone develop through the process of angiogenesis, taking place through different, bone-specific mechanisms. Impaired functioning of the bone blood vessels may be associated with the occurrence of some skeletal and systemic diseases, i.e., osteonecrosis, osteoporosis, atherosclerosis or diabetes mellitus. When a disease or trauma-related large bone defects appear, bone grafting or bone tissue engineering-based strategies are required. However, a successful bone regeneration in both approaches largely depends on a proper blood supply. In this paper, we review the most recent data on the functions, molecular characteristics and significance of the bone blood vessels, with a particular emphasis on the role of angiogenesis and blood vessel functioning in bone development and regeneration, as well as the consequences of its impairment in the course of different skeletal and systemic diseases.

Research within the anatomical sciences often relies on human cadaveric tissues. Without the good will of these donors who allow us to use their bodies to push

The Achilles tendon (AT) consists of fibers originating from the soleus muscle (SOL), which lies deep, and the medial (GM) and lateral (GL) heads of the gastrocnemius muscle, which lie superficial. As the fibers descend toward the insertion of the AT, the individual subtendons twist around each other. The aim of this study was to investigate the twisted structure of the AT and its individual subtendons. Specimens of the AT, with preserved calcaneal bone and a fragment of the triceps surae muscle, were obtained from 53 fresh-frozen, male cadavers (n=106 lower limbs). The angle of torsion of each of the AT's subtendons was measured using a specially designed and 3D-printed tool. The mean distance between the most distal fibers of the triceps surae muscle and the superior border of the calcaneal bone was 60.77±14.15 mm. The largest component of the AT at the level of its insertion into the calcaneal bone is the subtendon from the GL (44.43%), followed by the subtendon from SOL (27.89%), and the subtendon from GM (27.68%). The fibers originating from the GM rotate on average 28.17±15.15°, while the fibers originating from the GL and SOL twist 135.98±33.58° and 128.58±29.63°, respectively. The torsion of superficial fibers (GM) comprising the AT is significantly lower than that of deeper fibers (GL and SOL). The cross-sectional area of the AT is smaller at the level of the musculo-tendinous junction than at the level of its insertion. This study illustrates the three types of the AT with differently twisting subtendons, as well as a generalized model of the AT. Types of AT torsion may potentially alter the biomechanical properties of the tendon, thus possibly influencing the pathophysiologic mechanisms leading to the development of various tendinopathies.

Evidence-Based Anatomy (EBA) is the concept of applying evidence-based principles and research methods to the anatomical sciences. While narrative reviews are common in the anatomical sciences, true systematic reviews (SR) and meta-analysis (MA) are only beginning to grow in popularity. In order to enhance the quality of future EBA studies, and ensure the clinical reliability of their results, a uniform methodology is needed. In this paper, we present a step-by-step methodological guide for performing SRs and MAs of anatomical studies. We address the EBA-specific challenges in each step of the SR and MA process, and discuss methods and strategies to overcome these difficulties. Furthermore, we discuss in detail the statistical methods used in MA of anatomical data, including multi-categorical and single-categorical pooled prevalence estimates, as well as pooled means of one group. Lastly, we discuss the major limitations of EBA, including the lack of a proper quality assessment tool for anatomical studies. The methods described in this paper present a uniform road map for future EBA studies.

Background and ObjectiveThe course and branches of the median nerve (MN) in the wrist vary widely among the population. Due to significant differences in the reported prevalence of such variations, extensive knowledge on the anatomy of the MN is essential to avoid iatrogenic nerve injury. Our aim was to determine the prevalence rates of anatomical variations of the MN in the carpal tunnel and the most common course patterns and variations in its thenar motor branch (TMB).Study DesignA systematic search of all major databases was performed to identify articles that studied the prevalence of MN variations in the carpal tunnel and the TMB. No date or language restrictions were set. Extracted data was classified according to Lanz's classification system: variations in the course of the single TMB—extraligamentous, subligamentous, and transligamentous (type 1); accessory branches of the MN at the distal carpal tunnel (type 2); high division of the MN (type 3); and the MN and its accessory branches proximal to the carpal tunnel (type 4). Pooled prevalence rates were calculated using MetaXL 2.0.ResultsThirty-one studies (n = 3918 hands) were included in the meta-analysis. The pooled prevalence rates of the extraligamentous, subligamentous, and transligamentous courses were 75.2% (95%CI:55.4%-84.7%), 13.5% (95%CI:3.6%-25.7%), and 11.3% (95%CI:2.4%-23.0%), respectively. The prevalence of Lanz group 2, 3, and 4 were 4.6% (95%CI:1.6%-9.1%), 2.6% (95%CI:0.1%-2.8%), and 2.3% (95%CI:0.3%-5.6%), respectively. Ulnar side of branching of the TMB was found in 2.1% (95%CI:0.9%-3.6%) of hands. The prevalence of hypertrophic thenar muscles over the transverse carpal ligament was 18.2% (95%CI:6.8%-33.0%). A transligamentous course of the TMB was more commonly found in hands with hypertrophic thenar muscles (23.4%, 95%CI:5.0%-43.4%) compared to those without hypertrophic musculature (1.7%, 95%CI:0%-100%). In four studies (n = 423 hands), identical bilateral course of the TMB was found in 72.3% (95%CI:58.4%-84.4%) of patients.ConclusionsAnatomical variations in the course of the TMB and the MN in the carpal tunnel are common in the population. Thus, we recommend an ulnar side approach to carpal tunnel release, with a careful layer by layer dissection, to avoid iatrogenic damage to the TMB.