[Factors affecting blood loss in total knee arthroplasty patients]. / Cimbenici koji utjecu na gubitak krvi u bolesnika kod ugradnje totalne proteze koljena.

The aim of the study was to identify the factors affecting major blood loss in patients undergoing total knee arthroplasty (TKA), in order to reduce blood loss and requirements for blood transfusion. This prospective randomized study included 80/184 patients treated by TKA at University Hospital of Traumatology, Zagreb, Croatia, from January 2005 till December 2007. The following parameters were analyzed: patient age, sex, body mass index (BMI), arterial blood pressure, preoperative hemoglobin level and hemoglobin level preceding blood transfusion, length of surgery, blood loss and volume of blood transfused. According to patient age, there were no differences in the length of surgery, blood loss volume, hemoglobin level before blood transfusion and use of blood transfusion. Older patients had lower hemoglobin level before blood transfusion and received greater volumes of blood transfusion, but the difference was not statistically significant. Male patients had a significantly higher preoperative hemoglobin level as compared to female patients (P = 0.012). The mean volume of blood loss and of transfused blood was larger in male than female patients, however, the difference did not reach statistical significance. According to BMI, there were no differences in the length of surgery, blood loss, volume of transfused blood and hemoglobin level before transfusion. Patients with a lower preoperative hemoglobin level did not lose more blood during and after surgery, but the requirement for blood transfusion was significantly higher (P = 0.014). Hypertensive patients had a statistically greater perioperative blood loss (P = 0.038), but did not receive more transfused blood (P = 0.494). Preoperative hemoglobin level was higher in patients with elevated arterial blood pressure than in those with normal blood pressure, but the difference was not statistically significant (P = 0.595). Hemoglobin level before blood transfusion was also higher in hypertensive patients than in those with normal blood pressure, but it was not statistically significant (P = 0.288). In patients with longer duration of surgery, blood loss and volume of blood transfused blood were statistically significantly greater (P = 0.003 and P = 0.015, respectively). Study results yielded a significant positive correlation between the length of surgery and the volume of blood loss (r = 0.282; P = 0.011) as well as between the length of surgery and the volume of blood transfused (r = 0.362; P = 0.001). A significant negative correlation was established between the preoperative hemoglobin level and application of blood transfusion (r = -0.250; P = 0.025). Patients with hypertension had a significantly larger blood loss volume as compared to patients with normal arterial pressure (P = 0.038) and received more blood transfusions than patients with normal blood pressure, but the difference was not statistically significant (P = 0.494). Age, sex and BMI had no statistically significant effect on blood loss volume and application of blood transfusion. Male patients had a significantly higher preoperative hemoglobin level (P=0.012), larger mean blood loss volume (P = 0.057) and received more blood transfusions than female patients, however, the difference did not reach statistical significance (P = 0.562). Based on study results, it is concluded that requirements for blood transfusion will be greater in patients with hypertension and lower preoperative hemoglobin level as well as in all cases with longer duration of surgery. To reduce the use of allogeneic blood transfusion, it is necessary to correct arterial blood pressure before surgery in hypertensive patients and also to magnify preoperative hemoglobin level if it is lower.

[Study of friction and loosening in hip endoprostheses]. / Ispitivanje trenja i rasklimavanja endoproteze kuka.

AIM: Like any other operative procedure, the implantation of hip prosthesis is associated with certain complications, which diminishes the value and purpose of such a procedure. One of the complications in artificial hip implantation is loosening of the alloplastic material. Therefore, the aim of this study was to examine the effect of lubrication on the torsional moment and its role in the loosening of the femoral component, using an experimental mechanical model. The following hypothesis was tested: the magnitude of torsional loading in the "bone-endoprosthesis-bone cement system" is similar to any other known loading. METHODS: The testing device was constructed with the possibility of simulation of positions similar to original performances in the implanted hip prosthesis. It refers primarily to the possibilities of achieving definite forces and velocities. The intention was to point quantitatively to the role of friction moment between the acetabular and femoral endoprosthesis part. Trials were conducted by combining 7 types of loading and 4 kinds of lubrication: dry, water, plasma, and light oil. The testing joint (Ring's prosthesis) was connected through tensometric measuring shaft upon the working forepart oscillating mechanism. Graded by the changeable static loading by means of the pendulum and via lever mechanism the testing joint was loaded by force from 610 to 7137 N. As the cause of friction resistance in the moving joint, torque deformaties of the measuring shaft occurred. The testing joint enabled oscillating movement using a four-part mechanism. In this way, it was possible to define not only the maximum values of the frictional moment (or the coefficient of friction) during one movement cycle but also to examine its relation to the kind of lubrication. Change in the measuring torsional moment were computer recorded. Before each trial, the gauging of the complete outfit was performed. Thereafter, cleaning of the frictional surfaces of the whole outfit was done. RESULTS: The results obtained in combination with lubrication showed a slight increase in the values of the frictional moment. With dry lubrication and greater loading, an extremely progressive gradient of change was recorded. The course of change in the coefficient of friction was essentially different from the course of change in the frictional moment. It was noted particularly during trials with lubrication. In trials without lubrication, a constant increase of loading (force) resulted in a progressive increase in the coefficient of friction, similar to the friction moment. Such a character of the friction moment increase in the observed loading field was explained by the presence of boundary friction in cases with lubrication and by dry friction in cases without lubrication. In dry friction, scratching occurs relatively early, at a loading of F = 1854 N. It occurs with substances of approximately the same hardness like Ring's prosthesis, where the acetabular and femoral prosthesis parts are of metal characteristics. CONCLUSION: The increase in the frictional moment within the observed loading range can be explained by the presence of bordering friction in cases with lubrication, and of dry friction in cases without lubrication. Contrary to this, dry friction relatively early leads to "scratching", especially when sparing materials of similar hardness are combined.

All-inside arthroscopic suturing technique for meniscal ruptures.

The most frequent indication for surgical treatment of the knee is lesion of the meniscus. The "all inside" arthroscopic technique with bioresorptive material for meniscus lesion is becoming the most popular treatment. This prospective study included 10 patients with posterior meniscal horn lesion operatively treated at Sports Traumatology Department. The "all inside" technique was performed by intra-articular application of bioresorptive pins-Darts sticks or Meniscus Viper and bioresorptive string. Patients were followed up for 2-6 months postoperatively and graded according to the IKDC 2000 scale. All surgical treatments showed satisfactory results. Young patients with acute longitudinal peripheral lesion-posterior horn lesions, in the red-red or red-white meniscal zone, 1-2 centimeters long are most appropriate for this type of treatment. In these patients, this technique proved to be superior and free from the risk of neurovascular damage. For better authentication of this conclusion, additional prospective randomized studies should be performed.