A Method for Prediction of Femoral Component of Hip Prosthesis Durability due to Aseptic Loosening by Using Coffin/Manson Fatigue Model.

The purpose of this work is to develop a new model estimate of the fatigue life of a hip prosthesis due to aseptic loosening as a multifactorial phenomenon. The formula developed here is a three-parameter model based on Basquin's law for fatigue, eccentric compression formula for the compressive stress and torsion in the prosthesis due to the horizontal components of the contact force. With our model, we can accurately predict the durability of a hip prosthesis due to the following four parameters: body weight, femoral offset, duration, and intensity of daily physical activities of a patient. The agreement of the prediction with the real life of the prosthesis, observed on 15 patients, is found to be adequate. Based on the formula derived for a particular implant, there was a high degree of concurrence between the model-predicted and actual values of aseptic loosening (durability) proved by the Mann-Whitney U test. By virtue of the validated model, it is possible to predict, quantitatively, the influence of various factors on the hip life. For example, we can conclude that a 10% decrease of a patient's body mass, with all other conditions being the same, causes 5% increase of the hip fatigue life.

Microsurgical anatomy of the extra-articular segment of middle genicular artery.

PURPOSE: Knowledge of the incompletely studied microsurgical anatomy of the extracapsular part of the middle genicular artery (MGA) could imply an educational value and clinical significance because of the possible risk of injury during knee surgery. METHODS: Thirty formol-fixed cadaveric lower limbs in full extension were dissected and used for the measurements of MGA parameters. A second group of measurements was performed on distal ends of 30 adult femurs. Two fresh injected cadaveric lower limbs were explored by means of multidetector computed tomographic angiography (MDCTA). RESULTS: The MGA originated from the popliteal artery (PA), facing the lateral half of the intercondylar fossa in 16 (53.4 %) specimens, together with the superior lateral genicular artery (SLGA) in ten (33.3 %) cases, or from the same point of origin with SLGA and superior medial genicular artery (SMGA) in 4 (13.3 %) cases. The MGA averaged 15.6 mm in length and 1.8 mm in the outer diameter. After its curved direction the MGA entered the posterior capsule. The average distances of the point of MGA entrance into the joint capsule were as follows: to the lateral femoral epicondyle it was 34.88 mm, to the medial femoral epicondyle 46.38 mm, 5.74 mm lateral to the posterior midline, with an average vertical distance to the femoral subcondylar plane of 28.73 mm. CONCLUSION: This detailed anatomical examination with measurements of the extracapsular part of a MGA could be of clinical importance and useful in knee surgery for the prevention of vascular injury of MGA and PA, as well as in radiological examination of the knee region.

Computer and experimental analyses of the stress state in the cement hip joint endoprosthesis body.

BACKGROUND/AIM: One of the possible complications after implantation of a cement hip-joint endoprosthesis is frac- ture in the endoprosthesis body. Fractures arise from overload or material fatigue of which an implant is made. The purpose of this research was to define the intensity of maximum stress and the positions of a critical cross-section in the endoprosthesis body. METHODS: Unilaterally changing forces which act on the hip joint during walking as well as the loads result in flexible deformations of the endoprosthesis body. Biomechanical analysis of the forces acting on the hip joint determine their direction and intensity, whereas on the basis of Gruen's classification of the endoprosthesis body loosening the level of fixation is established. The bodies of cement hip joint endoprosthesis are made of cobalt-chromium-molybdenum (CoCrMo) alloy, suitable for vacuum casting, are submitted to the analysis. Analysis of the critical stress in the endoprosthesis body was performed on the endoprosthesis body by means of the finite element method. The experimental verification of the obtained results was carried out on the physical prototype under laboratory conditions. RESULTS: Computer analysis, by means of the finite element method, determined the stress state by calculation of the maximum Von Mises stress and critical cross-sections for different angles of the resultant force action. The results obtained by the computer and experimental method correlate and are comparable to the results of similar analyses conducted on various endoprosthesis types. CONCLUSION: The analyses described in the paper make the basis for improving the process designing of hip joint endoprostheses and their customization to each individual patient (custom made).

Semitendinosus tendon regeneration after anterior cruciate ligament reconstruction: can we use it twice?

PURPOSE: It has been demonstrated that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament (ACL) reconstruction. Ultrasound studies and guided biopsies of the regenerated tendon have shown compatibility and resembling features of the normal tendon. The question is if this neo-tendon is biologically and functionally adequate for re-use? METHODS: Two randomised groups of 150 volunteers were followed up for two years after harvesting the semitendinosus only (25) or the semitendinosus and gracilis tendons (25) in ACL reconstruction. The patients were followed up with clinical and ultrasound examinations, biopsies and histological tests. Surgical exploration was done in three patients for macroscopic verification. The injected arteries of four lower limbs were dissected and the tendon's arterial supplies were examined. RESULTS: Seventy-two percent of the cases showed regeneration of the semitendinosus tendons. The neotendons were inserted mostly below the knee joint (83.3%) where they had fused with the gracilis tendon, and above the joint (60%) when the gracilis was harvested as well. The isokinetic strength of the hamstrings and quadriceps was not significantly diminished on the operated side. A macroscopic and histological analysis of the regenerated tendons demonstrates close resemblance to normal anatomy, with focal areas of fibrosis. In one patient the regenerated tendon was used for medial patellofemoral ligament reconstruction. CONCLUSION: The semitendinosus muscle can recover and the tendon has great potential to regenerate after harvesting for ACL reconstruction. Our data suggest that the regenerated tendons could be used for iterative ligament reconstruction.

[The role of the posterior tibial slope on rupture of the anterior cruciate ligament].

BACKGROUND/AIM: Posterior tibial slope is one of the most citated factors wich cause rupture of the anterior cruciate ligament (ACL). The aim of this study was to determine the association of a greather posterior tibial slope on the lateral condyle, that is a lesser posterior tibial slope on the medial condyle, with ACL rupture. METHODS: The patients were divided into two groups. The study group included the patients with chronic instability of the knee besause of a previous rupture of ACL. The control group included the patients with knee lesion, but without ACL rupture. Posterior tibial slope measuring was performed by sagittal MR slices supported by lateral radiograph of the knee. We measured posterior tibial slope on lateral and medial condyles of the tibia. Using these values we calculated an average posterior tibial slope as well as the difference between slopes on lateral and medial condyles. RESULTS: Patients with ACL rupture have highly statistically significantly greather posterior tibial slope (p < 0.01) on lateral tibial condyle (7.1 degrees : 4.5 degrees) as well as statistically significantly lesser posterior tibial slope (p < 0.05) on medial tibial condyle (5.9 degrees : 6.6 degrees) than patients with intact ACL. CONCLUSION: Great posterior tibial slope on lateral tibial condyle associated with the small posterior tibial slope on the medial tibial condyle, that is a positive differentce between lateral and medial tibial condyles are factors wich may cause ACL rupture.

The third branch of the main trunk of the left coronary artery in Cercopithecus aethiops sabaeus. Is the nonhuman primate model appropriate?

The aim of this study was to investigate the morphometry of branching patterns of the main trunk of the left coronary artery (MT of LCA) in nonhuman primates, and comment on the current nomenclature. The biometric study was performed using stereomicroscopic dissection of hearts of healthy and fertile nonhuman primates (Cercopithecus aethiops sabaeus) of both sexes. Our results reveal that the MT of LCA terminates in a bifurcation into the anterior interventricular branch (AIB) and the circumflex branch (CB) (74.6%), trifurcation into the AIB, CB, and diagonal branch (DB) (23.6%), or occasionally quadrifurcation into the AIB, CB, and two DBs (1.8%). This is similar to the case in humans. Furthermore, two morphological aspects of the DB spatial distribution, in addition to its branching pattern, resemble the DB in humans. Myocardial bridges observed over the DB in the Cercopithecus aethiops heart further contribute to the similarity with humans. The resemblance of the DB and its branches to their human counterparts make them a suitable model for experimental study on coronary circulation.

Predicting ACL rupture in the population actively engaged in sports activities based on anatomical risk factors.

The purposes of this article were identification (ie, verification and gradation) of anatomical risk factors that lead to anterior cruciate ligament (ACL) injury and determination of the probability of ACL injury among the population actively engaged in sports activities. We evaluated 66 patients divided into 2 groups: 33 patients in the examined group diagnosed with ACL lesion, and 33 patients in the control group diagnosed with patellofemoral pain. Patients were matched by age, sex, type of lesion, and whether the lesion was left or right sided. Measurements were carried out by radiography and magnetic resonance imaging. The study examined 32 anatomical factors. After identifying factors that lead to ACL injury, the following were determined: the coefficient of significance for each individual factor via the discriminant analysis and the canonical discriminant (i.e., canonical correlation). Fifteen factors in men and 8 factors in women were differentiated as having influence on ACL injury. Based on these factors, it was determined whether the patients belonged to the examined or the control group with a success rate of 100% in men (100% sensitivity and specificity) and 91.7% in women (100% sensitivity and 83.3% specificity). The anatomy of the ACL prone to rupture and of the skeletal structures influencing it is significantly different from the anatomy of the ACL ligament resistant to injury. The probability of precise prognosis of ACL injury based on differentiated anatomical factors is 88.9% in men and 75.7% in women actively engaged in sports activities.

Prospective evaluation of the prevalence of Helicobacter pylori in abdominal surgery patients.

BACKGROUND/AIMS: Helicobacter pylori infection is accepted to be associated with two mutually exclusive diseases duodenal ulcer and gastric cancer. The aim of this study was to explore the relationship and prevalence of Helicobacter pylori infection in different surgical diseases. METHODOLOGY: With use of simple serologic assays for detecting IgA and IgG antibodies to HP antigen, we studied the association of infection with HP and 15 surgical diseases. RESULTS: The prevalence of HP was 68.60% (results of assays were positive for 142 patients out of 207). This study confirmed statistically significant correlation between HP seropositivity and pancreatic cancer (p = 0.02), hepatocellular cancer (p = 0.000), gastric cancer (p = 0.01), colon cancer (p = 0.002), rectal cancer (p = 0.001), intestinal cancer (p = 0.026), stenosis pylori (p = 0.01), ulcer diseases (p = 0.004), jaundice (p = 0.002); statistically significant inverse association between HP seropositivity and the acute appendicitis (p = 0.013) and no correlation with HP infection and cholecystitis (p = 0.716), cholelithiasis (p = 0.06), and ulcer hemorrhage (p = 0.064). CONCLUSION: The use of simple serological tests to identify patients with HP infection could help to calculate the risk of development of severe gastrointestinal diseases.

[Oversights in the care of severe injuries].

Question of missed injuries is more often a question of human errors: task execution errors, procedural errors, communication errors, decision errors and noncompliance. Missed injuries are those which are not idetified in the first three days of hospitalisaation. This theme is not popular among physicians. Literature data mention percent from 3-29% missed injuries overall. The underlying causes errors are: false attributin, false negative prediction and false lebeling. False attribution involves a tendency to incorrectly link a clinical observation with an arroneous cause. This tendency also ignores one of the fundamental principles of the management of traumatic injury: that the index of suspicion should proceed on the basis of assumed wors resonable case scenario. Weaknesses of trauma systems: high patients volume, high-risk patients, long hours, changing set of resources, and problems sush bad admission planing, defficite anamnesis, defficite diagnostic procedures, bad communication, improvisation etc.

Laser-induced damages of different types of human gallbladder stones.

BACKGROUND/AIMS: Today, treatment of human calculi, and particularly those of gallbladder, is, to a large extent, less invasive procedure due to numerous non-invasive methods that have been developed. METHODOLOGY: CO2 laser of pulse (output 5W)(W-watt, SI unit system) and continual mode (output 15W) and diode laser (808 nm-nanometer, SI) were used for tests of fragmentation of gallbladder calculi in vitro. RESULTS: A total of 15 human gallbladder calculi of known size were examined, which had been collected during surgical interventions. Damages caused by laser were examined visually and by stereomicroscope (10 to 25 times magnification). During testing, the dependence of fragmentation on the type of laser effect, as well as the degree of fragmentation on the type of tested calculus was noted. Different types and dimensions of damage caused by various laser beams, as well as coloration changes of superficial layers in relation to the type of tested calculi was noticed. CONCLUSION: Accordingly, in this specific case, the priority for removal of gallbladder calculi by ablation will be given to diode laser.

Correlation between the morphometric parameters of the anterior cruciate ligament and the intercondylar width: gender and age differences.

The study was conducted on 50 cadavers (32 male and 18 female, aged 15-53 years; mean 34; SD 11) with intact anterior cruciate ligament (ACL), without diagnosed gonarthrosis of the knee joint. The following anatomical parameters of the ACL were measured: the length of anteromedial and posterolateral bundle, the mean length and the width of the ligament, the length and width of tibial insertion, the length and width of femoral insertion. The intercondylar width was measured at the level of popliteal groove. The width of male intercondylar notch (22 mm) was statistically significantly greater (P < 0.05) than the width of female intercondylar notch (18 mm). The width of the male ACL (12 mm) was significantly greater (P < 0.05) than the width of the female ACL (10 mm). The length of the male ACL femoral insertion (14 mm) was statistically significantly greater (P < 0.05) than in the female ACL femoral insertion (12 mm). Accordingly, with greater width of intercondylar notch, men have wider ACL than women. ACL width is in positive correlation with the male intercondylar notch width but it is not in correlation with the female intercondylar notch width. The width of male intercondylar notch correlates with the length and width of ACL femoral insertion. Taking into account the length and width of femoral insertion in examined cadaver knees, double bundle reconstruction would theoretically be possible in 76% of cases.

The position of anterior cruciate ligament in frontal and sagittal plane and its relation to the inner side of the lateral femoral condyle.

The position of the anterior cruciate ligament (ACL) is one of the anatomical factors that lead to its injury. We evaluated 66 patients divided in two groups: 33 patients in the examined group with a diagnosed ACL lesion, and 33 patients in the control group with diagnosed patellofemoral pain. The patients were matched by age, sex, type of lesion (whether it was profession related) and whether the lesion was left or right sided. Measurements were carried out by radiography and MRI. The following positions of angles were measured: the angle of ACL in sagittal and frontal plane, the angle of the inner side of lateral condyle in frontal and horizontal plane and the angle between the course of ACL and the inner side of lateral condyle. In our study there is a significant difference (P < 0.05) in the degree of the ACL angles in the frontal plane between the examined group (74.5 degrees) and the control group (70.6 degrees). Also, there was a significant difference (P < 0.05) in the degree of the ACL angle in the sagittal plane between the examined group (48 degrees ) and the control (50.4 degrees). The angle between the inner side of the lateral condyle of the femur and the ACL of the examined group (32.9 degrees) differs significantly (P < 0.01) from the same angle of the control group (40.6 degrees ). According to the results of our study it appears that the increment of the ACL angle in the frontal plane, the decrement of the ACL angle in the sagittal plane and the decrement of the angle between the ACL and the inner side of the lateral condyle in the frontal plane are associated with the rupture of the ACL.