Marija Hribernik

Anatomical variations in the pattern of the right hepatic veins: possibilities for type classification

A morphological study of the right hepatic veins (RHVv) was conducted based on the shape and the confluence pattern of the superior right hepatic vein (SRHV) and the presence of accessory right hepatic veins. The study was performed in 110 undamaged, randomly selected, cadaveric human livers prepared using the corrosion cast methodology. The principles for classifying the RHVv into types were as follows: the length of the vein trunk, the confluence of 2 or 3 main tributaries that form a trunk, and the accessory right hepatic veins that modify the venous drainage of the right side of the liver. Four types of SRHV were identified. Type 1 (20%), type 2 (40%) and type 3 (25%) were the most common, while type 4 (15%) was linked to the accessory right hepatic veins in cases where they drain a surgically important part of the liver. Accessory right hepatic veins were found in a total of 31 casts (28%). The hepatocaval confluence was studied and the tributary‐free part of the SRHV trunk before it entered the inferior vena cava was measured. The tributary‐free part of the SRHV was longer than 1 cm in 77% of the casts. Anastomoses between the terminal tributaries of the veins involved in the drainage of the right side of the liver were also investigated.

Failure Properties and Damage of Cervical Spine Ligaments, Experiments and Modeling

Cervical spine ligaments have an important role in providing spinal cord stability and restricting excessive movements. Therefore, it is of great importance to study the mechanical properties and model the response of these ligaments. The aim of this study is to characterize the aging effects on the failure properties and model the damage of three cervical spine ligaments: the anterior and the posterior longitudinal ligament and the ligamentum flavum. A total of 46 samples of human cadaveric ligaments removed within 24-48 h after death have been tested. Uniaxial tension tests along the fiber direction were performed in physiological conditions. The results showed that aging decreased the failure properties of all three ligaments (failure load, failure elongation). Furthermore, the reported nonlinear response of cervical ligaments has been modeled with a combination of the previously reported hyperelastic and damage model. The model predicted a nonlinear response and damage region. The model fittings are in agreement with the experimental data and the quality of agreement is represented with the values of the coefficient of determination close to 1.

DEEP INFERIOR EPIGASTRIC PERFORATOR FLAP: AN ANATOMICAL STUDY OF THE PERFORATORS AND LOCAL VASCULAR DIFFERENCES

The objective of this study was to determine precise localization and external diameter of the lower abdominal wall perforators as well as to investigate some vascularity differences between the same parts of perfusion zones II and III according to Hartrampf perfusion zones. The study was performed on 10 fresh cadavers (20 hemiabdomens) using the gelatin injection technique. All perforators were identified, and their localization and diameter were noted. Measurements were made at the level of the fascia. We noted localization and diameter of arteries on cross‐sectional planes of either part of the flap. The median sum of the external diameter of all arteries in zone I was 17.01 mm. The median sum of the external diameter of all arteries in the medial 1/3 part of zone III was 4.17 mm, and in the medial 1/3 part of zone II, it was 0.96 mm. The median sum of the external diameter of all arteries in the intermediary 1/3 part of zone III was 2.16 mm, whereas in the intermediary 1/3 part of zone II, it was 0.81 mm. Significant differences were recorded between proximal and middle horizontal regions of zones II and III and between medial vertical part of zone III and medial vertical part of zone II. Anastomoses between zones I and II are considerably smaller compared with anastomoses between zones I and III. The best vascularized parts of the lower abdominal wall were perfusion zone I, then the inner 2/3 of zone III and medial 1/3 of zone II.

Retracted: Muscles within muscles: a tensiomyographic and histochemical analysis of the normal human vastus medialis longus and vastus medialis obliquus muscles

The aim of this study was to show the connection between structure (anatomical and histochemical) and function (muscle contraction properties) of vastus medialis obliquus (VMO) and vastus medialis longus (VML). The non‐invasive tensiomyography (TMG) method was used to determine the contractile properties (contraction time; Tc) of VML and VMO muscle, as a reflection of the ratio between the slow and fast fibers in two groups of nine young men. VML and VMO significantly (P < 0.01) differ in the proportion of type 1 (59.6: 44%) and type 2b (6.3: 15%) fibers. The VML muscle is almost entirely composed of type 1 and type 2a fibers. In many samples of this muscle no type 2b fibers were found. The proportion of slow‐twitch type 1 fibers is nearly twice as high as the proportion of fast‐twitch type 2a fibers. These observations indicate that VML is a slower and more fatigue‐resistant muscle than VMO muscle. These characteristics correspond to the different functions of the VML, which is an extensor of the knee, and to the VMO, which maintains the stable position of the patella in the femoral groove. Our results obtained by TMG provided additional evidence that muscle fibers within the segments of VM muscle were not homogenous with regard to their contractile properties, thereby confirming the histochemical results. Tc can be attributed to the higher percentage of slow‐twitch fibers – type 1. The statistically shorter Tc (P ≤ 0.001) of VMO (22.8 ± 4.0 ms) compared with VML (26.7 ± 4.0 ms) in our study is consistent with previously found differences in histochemical, morphological and electrophysiological data. In conclusion, the results of this study provide evidence that the VML and VMO muscles are not only anatomically and histochemically different muscles, but also functionally different biological structures.

Anatomy of the ligamentum venosum arantii and its contribution to the left hepatic vein and common trunk control. A study on cadaveric livers.

Background: The control of the left hepatic vein (LHV) and the common trunk of the middle hepatic vein (MHV) and LHV (CT) is considered difficult during liver resection and could be improved by detailed knowledge on the ligamentum venosum Arantii (LV). Aim: The aim of this study was to describe the LV and its connections to the LHV and the CT and to present surgical relevance of the obtained data. Material and Methods: During autopsy of 50 cadavers of both sexes, the LV was exposed, measured and then dissected, simulating a surgical maneuver to facilitate the approach to the LHV and CT. The extrahepatic parts of the LHV, MHV and CT were measured. Results: The LV was 52–70 mm long and 5–8 mm thick. It had a fibrotic structure and was not patent in 96% of the cases. The extrahepatic part of the LHV measured 3–19 mm, that of the MHV 3–18 mm and that of the CT 4–15 mm. Conclusion: LV dissection facilitated extraparenchymatous clamping of the hepatic veins: the extrahepatic parts of the LHV and CT measured >3 mm in 86 and 84% of the cases, respectively.

Anatomy and Surgical Relevance of the Hepatocaval Ligament

Background: There are nearly no data on the hepatocaval ligament (HCL) in the anatomical literature, though it is of high importance during surgery of the right hemiliver. Aim: The aim of this study was to determine the frequency of the HCL, its description and its relations to the inferior vena cava (IVC) and the right hepatic vein (RHV) as well as the evaluation of the surgical relevance of the data obtained. Materials and Methods: The dissection of the livers of 43 cadavers of both sexes was performed and the presence of the HCL was established. The ligament was measured and dissected to expose the IVC and the extrahepatic part of the RHV from its inflow to the liver parenchyma. Results: The ligament was present in 77% of the cases. It was 12–35 mm long and 3–18 mm wide. The extrahepatic part of the RHV was 2–12 mm long. Conclusion: Dissection of the HCL revealed the terminal extrahepatic part of the RHV in all cases. Anatomically, resection of the right hemiliver with elective vascular control would be possible in 85% of the cases in which the length of the extrahepatic part of the RHV was ≧3 mm.

Congruence between the courses of the biliary ductal and the hepatic arterial systems.

The development of diagnostic methods and new surgical techniques means it is increasingly important to have accurate knowledge of the anatomy of the hepatic arterial and biliary systems, including their variations, at extrahepatic and intrahepatic levels. The aim of this study was to determine how often the biliary and arterial systems run together and branch in the same pattern. Fifty corrosion casts of the liver were used to analyse the origin and branching patterns of arteries and the confluences of bile ducts. In addition, both systems were analysed to determine the frequency of normal arrangements and variations. The congruence of the course of both systems was analysed at the porta hepatis and in the left and right hemilivers down to the segmental level. A congruent course of the arterial and the biliary systems was identified in 38% of cases at the porta hepatis, in 32% of cases in the left hemiliver and in 30% of the right hemiliver. The congruence of both systems at the porta hepatis and in the left hemiliver was identified only if both systems were normal. In the right hemiliver, however, the congruence of both systems was identified even when both systems were variable, but only in 10% of cases. The results of the study show that, on the basis of knowledge of the course and branching of one system, the other system cannot be predicted.

A Novel Approach to Measuring Muscle Mechanics in Vehicle Collision Conditions

The aim of the study was to evaluate a novel approach to measuring neck muscle load and activity in vehicle collision conditions. A series of sled tests were performed on 10 healthy volunteers at three severity levels to simulate low-severity frontal impacts. Electrical activity—electromyography (EMG)—and muscle mechanical tension was measured bilaterally on the upper trapezius. A novel mechanical contraction (MC) sensor was used to measure the tension on the muscle surface. The neck extensor loads were estimated based on the inverse dynamics approach. The results showed strong linear correlation (Pearson’s coefficient r¯P = 0.821) between the estimated neck muscle load and the muscle tension measured with the MC sensor. The peak of the estimated neck muscle force delayed 0.2 ± 30.6 ms on average vs. the peak MC sensor signal compared to the average delay of 61.8 ± 37.4 ms vs. the peak EMG signal. The observed differences in EMG and MC sensor collected signals indicate that the MC sensor offers an additional insight into the analysis of the neck muscle load and activity in impact conditions. This approach enables a more detailed assessment of the muscle-tendon complex load of a vehicle occupant in pre-impact and impact conditions.

Knee stiffness and viscosity: New implementation and perspectives in prosthesis development

The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.

Human body modelling for traffic accident analysis

A traffic accident is a complex phenomenon with vehicles and human beings involved. During a collision, the vehicle occupant is exposed to substantial loads, which can cause the occupant injuries that depend on the level of passive safety, as well as on the occupants individual characteristics. Correct estimation of injury severity demands a validated human body model and known impact conditions. A human body modelling procedure for the purpose of accident analysis is introduced. The occupant body has been modelled as a multibody system with rigid body segments connected. Geometrical and inertial properties of individual body segments were estimated using computed tomography. Frontal impact conditions were simulated on a sled test facility, while the human body dynamic response was measured. Comparison of experimental data and computer simulation revealed an influence of joint resistive properties on the occupant motion in collisions. The difference between measured and simulated response was minimised using optimisation method. Individualised human body modelling procedure enabled better prediction of the occupant motion during vehicle collision and thus more precise estimation of possible injuries in real-life traffic accidents.