Comparison of Modified Transiliac Internal Fixators: Mechanical Testing on Pelvic Models.

PURPOSE OF THE STUDY Vertically unstable transforaminal sacral fractures can be stabilized with several types of transiliac internal fixators (TIFI): the classical one (TIFI-C), the supraacetabular one (TIFI-A) and by dual application of TIFI (DTIFI). MATERIAL AND METHODS Pelvic models made of solid foam (Sawbones 1301) were used in the study. Mechanical loading tests were performed in order to assess the stiffness of the studied pelvic structures. The stiffness of the intact model was approximated as the slope of load/displacement curve. Then vertically unstable right-sided linear transforaminal fracture was created and subsequently fixed by TIFI-C, TIFI-A and DTIFI (each fixator for a separate model). The fixation techniques were compared based on the ratio between the stiffness of the treated and of the intact pelvis. Motion of the posterior pelvic structures and their deformations were measured using a photogrammetric system with four synchronous cameras. Loads applied at the base of sacrum and sacral base displacements were recorded by the testing device and used to assess the stiffness of the model structure. A dedicated load cell and a monoaxial extensometer were utilised. Every measurement was repeated at least 10 times. Obtained data were analysed by one way ANOVA test with post hoc comparison by Tukey HSD test. RESULTS Mean stiffness ratio (±1SD) of pelvic structure was 0.638 ± 0.005 for TIFI-C, 0.722 ± 0.014 for TIFI-A and 0.720 ± 0.008 for DTIFI. Dual transiliac internal fixation and supraacetabular fixation were superior to the classical one (p < 0.0001), but DTIFI and TIFI-A stiffness ratios were statistically equivalent (p = 0.9112). CONCLUSIONS Results of the mechanical analysis using pelvic models indicate that for linear vertical transforaminal sacral fracture without comminuted zone, an application of either TIFI-A or DTIFI provides significantly higher stiffness of the lateral pelvic segment than application of TIFI-C. Key words: transforaminal sacral fracture, transiliac internal fixator, dual TIFI, stability, biomechanics, digital image correlation.

[Minimally invasive stabilization of posterior pelvic ring injuries with a transiliac internal fixator and two iliosacral screws: comparison of outcome]. / Miniinvazivní stabilizace poranení zadního pánevního segmentu transiliakálním vnitrním fiátorem a dvema iliosakrálními srouby: srovnání funkcních výsledku

PURPOSE OF THE STUDY: A comparison of radiological and clinical results between dorsal pelvic segment stabilization with a transiliac internal fixator (TIFI) and that with two iliosacral screws (IS). MATERIAL AND METHODS: In this prospective study, both the TIFI and the IS group had 32 patients. The majority of injuries were assessed as type C1.3 because only patients with a high-energy mechanism of injury were included. Radiological results were evaluated according to the Matta scoring system and clinical outcome using the Majeed score and the Pelvic Outcome Score. Categorical data were evaluated by the two-sided Fisher's exact test or Pearson's χ2 test and continuous data by Student's t-test. A test result with p<0.05 was considered statistically significant. RESULTS: In the TIFI group, the mean posterior displacement was 2.2 mm, in the IS group it was 1.9 mm (p=0.58542). The pelvic outcome scores in the TIFI group were: excellent, 28%; good, 12%; fair, 48.0%; and poor, 4 %; in the IS group they were: excellent, 11.1%; good, 22.2%; fair, 66.7%; and poor, 0.0% (p=0.51731). The Majeed scores were as follows: excellent, 56.0%; good, 16.0%; fair, 20.0%; poor 8.0 % for the TIFI group and excellent, 50.0%; good, 27.8%; fair, 11.1%; and poor, 11.1% for the IS group (p=0.70187). Within the total, average Majeed score was 80.64 points in TIFI, 80.67 in IS (p=0.99654). In a sub-analysis of unilateral transforaminal fractures (Pohlemann type II), the average score for TIFI was 82.8 points and only 53.5 points for IS; the differences were statistically significant (p=0.04517). No intraoperative complications were associated with TIFI and one injury to the superior gluteal artery (3.1%) and two iatrogenic neurological injuries with IS (6.3%; p=0.23810). In the TIFI group, the fixator was removed without complications. In the IS group, post-operative wound bleeding following screw removal occurred in three patients (20.0%; p=0.22414), complete extraction of screws and washers was successful only in seven patients (46.7%), washers were left in situ in six patients (40.0 %) and IS removal was not possible in two patients (13.3%). The difference in complications between the groups was highly significant (p=0.00220). DISCUSSION: The results of our study are in agreement with those of the relevant studies published recently as well as with the outcomes of transiliac plate fixation reported in the literature. TIFI implantation is preferred in transforaminal and central sacral fractures because, unlike iliosacral screws, it carries a low risk of excessive compression of the sacral foramina and iatrogenic neurological injury. There were no significant differences in clinical and radiological findings between TIFI and IS procedures. Only in unilateral transforaminal fracture the TIFI stabilization had better outcome, as shown by the Majeed score. The IS fixation was associated with a higher rate of complications not only in primary implantation, but also at implant removal. CONCLUSIONS: The TIFI technique is superior to the IS procedure in fixation of unilateral transforaminal fractures and provides a reasonable alternative to the existing types of minimally invasive fixation.

[Comparison of patellar pain after total knee arthroplasty with conventional versus individual femoral rotational alignment]. / Srovnání výskytu patelární bolesti po aloplastice kolenního kloubu u konvencne nebo individuálne nastavené rotace femorální komponenty.

PURPOSE OF THE STUDY: The aim of the study was to find out whether the frequency and intensity of patellar pain can be affected by individual rotational alignment of the femoral component in total knee arthroplasty, as compared with the standard 3 degrees of external femoral rotation in conventional procedures. MATERIAL AND METHODS: In randomly selected patients treated for knee osteoarthritis by total joint replacement between January 2007 and January 2011, the occurrence of patellar pain was assessed. The evaluated knees were allocated to two groups. Group 1 included 350 knee joints with conventional femoral rotational alignment, i.e., 3 degrees of external rotation. Group 2 comprised 380 knee joints with an individual rotational alignment of the femoral component based on the condylar twist angle. Post-operative anterior knee pain was assessed on the following scale: 1, no pain; 2, occasional mild pain; 3, moderate pain; 4, severe pain. RESULTS: In group 1, 312 knee joints were free from pain, 15 occasionally experienced mild pain, 15 had moderate and eight had severe pain. A total of 23 revision operations were performed for patellar pain at the anterior knee and pain around the patella refractory to non-steroidal anti-rheumatic and rehabilitation therapy. In group 2, there were 331 pain-free knees, 48 with occasional mild pain, one with moderate pain and no knee with severe pain. No revision surgery was required. One patient with moderate patellar pain underwent surgery for spinal canal stenosis; after that knee pain was only mild. The groups were compared, as to pain assessment results, using the test of equality of relative frequencies, i.e., score categories 1+2 versus 3+4 of 350 (group 1) equalled 23 (6.57%) were compared with 1 (0.26%) of 380 (group 2); the difference was significant (p < 0.001). Using the same test for comparison of the frequency of repeat operations, i.e., 23 (0.57%) of 350 (group 1) versus 0 (0%) of 380 (group 2), also gave a significant result (p = 0.001). DISCUSSION: Mild and occasional pain was recorded in both groups, suggesting that femoral component malrotation is not the only cause of patellar pain following total knee arthroplasty. A markedly lower incidence of moderate and severe pain and no need for revision surgery found in group 2 provides evidence that the use of individual rotational alignment of the femoral component is fully justified. CONCLUSIONS: An individual rotational alignment of the femoral component can significantly reduce the incidence of moderate to severe patellar pain or even need for revision surgery.

[Comparison and statistical evaluation of two methods of condylar twist angle measurement in total knee arthroplasty]. / Komparace a statistické zhodnocení dvou metod merení "condylar twist angle" u aloplastiky kolenního kloubu.

PURPOSE OF THE STUDY: The aim of this prospective randomised study was to compare and statistically analyse two methods of condylar twist angle (CTA) measurement in total knee arthroplasty in order to assess their applicability in routine practice. MATERIAL AND METHODS: The study included 238 patients with 256 sites undergoing total knee arthroplasty (TKA) in the period from January 2009 to May 2011. There were 93 men (nine with bilateral TKA) and 145 women (nine with bilateral TKA) with an average age of 69.3 years and a range of 47 to 88 years. The implants NexGen (Zimmer) and ADVANCE® Medial-Pivot Knee (Wright) were used. In each patient, CTA was measured before surgery by the radiologist on a multidetector CT SOMATOM 64 (Siemens) using the Yoshioki method. The other CTA measurement was made intra-operatively by the surgeon using our modification of the Hofmann method which involved the identification of a reference line for optimal rotational alignment of the femoral component. A STATISTICA 9.0 software package was used for statistical analysis. In addition to basic statistical data, selected data were presented in graphical forms as Box and Whisker's plots and histograms. Changes in CTA and differences between the groups were evaluated using the Wilcoxon signed-rank test. Relationships among the variables were studied using Spearman's correlation coefficient. RESULTS: The statistical analysis showed that the pre-operative CTA value obtained from CT scans was, on the average, higher by 0.5 degrees than the value from intra-operative measurement, as assessed at the level of significance p = 0.001 (signed- rank test). The intra-individual variability was lower than the inter-individual one (14.4% and 30.8%, respectively). This means that both methods are suitable for CTA measurement in the knee joint replacement procedures. Spearman's correlation coefficient was 0.6, which is the value of medium strong correlation. The post-operative CTA assessed on CT scans was in the range of 0 to 2 degrees in 87.5% of the patients. Both the pre-operative and intra-operative CTA values were significantly higher in women than in men (Wilcoxon two-sample test). There was no statistical difference between the left and the right side. DISCUSSION: Malrotation of the femoral component is one of the causes leading to patellar subluxation and pain in the front part of the knee. The post-operative CTA value should be zero. Optimal rotational alignment of the femoral component varies with each patient; in our study it was found in the range of 0 to 7 degrees on the basis of CTA values. We do not recommend 7 degrees of external rotation to be exceeded because of the risk associated with balancing the flexion gaps; nor do we recommend to set internal rotation of the femoral component for the risk of patellar complications. The difference of 0.5 degree found in the CTA value between the two measuring methods can be explained by individual differences in the anatomy of the medial epicondylar region, and by the use of only selected whole numbers (0, 3, 5, 7) in intra-operative measurements. This difference does not play any role in routine surgical procedures. CONCLUSIONS: The statistical evaluation of the results of CTA measurement with the two methods showed that both were equally suitable for routine total knee arthroplasty. The results of intra-operative CTA measurements are comparable with those obtained on CT scans; in addition, the intra-operative method is less expensive and eliminates exposure of the patient to radiation. CT-based CTA measurements are useful in the patients with chronic problems after TKA in whom femoral component malrotation needs to be either confirmed or ruled out.

[Radiographic measurements in total knee arthroplasty and their role in clinical practice]. / Radiologická merení u aloplastiky kolenního kloubu a jejich význam pro praxi.

PURPOSE OF THE STUDY: The aim of the study was to present the use of digital sciagraphy and computed tomography for pre- and post-operative measurements in total knee arthroplasty. The authors were interested, in the first place, in the optimal adjustment of femoral component rotation and a valgus angle if extra-articular deformities of the femur and/or the tibia were present. MATERIAL AND METHODS: Digital sciagraphic examination was carried out on an AXIOM ARISTOS (Siemens) apparatus using the software designed by us. In group 1 comprising 269 knee joints, in a standing and weight-bearing position with lower extremity neutral rotation, the valgus angle was measured and the entry point for the intramedullary rod of a femoral cutting block was deter- mined. Subsequently, the mechanical axis and extra-articular deformities of the femur and/or the tibia were found and the patella position in 30-degree flexion of the knee joint was assessed on axial images. Based on radiographic evaluation, relevant treatment for different types of disorders, including extra-articular deformity, was proposed. In group 2 consisting of 204 knee joints, the values of a condylar twist angle were measured on axial sections, using a Siemens Somatom Sensation 64 CT Scaner.The method of condylar twist angle measurement was developed and the values for men and women were obtained. RESULTS: In group 1, the mean values obtained for valgus knee deformity were: valgus angle, 5.4°; median, 5.5°; modus, 6.0°. Those for varus knee deformity were: valgus angle, 7.2°; median, 7.0; modus, 7.0. A normal knee joint alignment (mechanical axis of 0° to 5°) had the respective mean values of 6°; 6.0° and 6.0°. This group showed 76 extra-articular deformities (33.9 %). In group 2, for women the mean ± SD value of the condylar twist angle was 5.25° ± 1.68; and median and modus values were 5.0° and 4.0 °, respectively. For men, the respective values were 4.69° ± 1.33; 4.0° and 4.0°. DISCUSSION: The mean values of valgus angle and CTA found in this study are in agreement with the literature data. In the pre-operative planning it is necessary to take extra-articular deformities in consideration, to respect the entry point for the intra- medullary rod and to take a compromise solution for adjustment of the valgus angle of the femur and for tibial deformities. Also, in severe valgus and varus deformities of the knee, the maintenance of a neutral mechanical axis should be strictly observed. The optimal adjustment of femoral component rotation is individual and depends on the type of deformity and femoro-patellar joint pathology. The external rotation of a femoral component should be set in the range of 0° to 7°. CONCLUSIONS: Digital sciagraphy with suitable software and computed tomography contribute to radiographic measurements before and after total knee arthroplasty. They facilitate an accurate and quick measurement together with data storage. On examination in a standing weight-bearing position it is necessary to keep standard lower extremity neutral rotation. Computed tomography is recommended when more severe valgus and varus deformities and/or femoro-patellar pathology are present. The results of radiographic measurement analysis will allow the surgeon to plan the operative strategy and select a suitable type of implant.

[Mediolateral episiotomy and anal sphincter trauma]. / Mediolaterální epiziotomie a poranení análního sfinkteru.

OBJECTIVE: A summary of recent knowledge of the correlation between mediolateral episiotomy and anal sphincter injury. DESIGN: Review. SETTING: Department of Gynaecology and Obstetrics, Charles University and University Hospital Pilsen. CONCLUSIONS: The methodology of most studies is not well managed. Four problematical points were identified: definition of the mediolateral episiotomy, practical execution of the mediolateral episiotomy, diagnostics of perineal trauma and classification of the perineal trauma. Mediolateral episiotomy is often deficiently defined. Definitions differ depending on individual textbooks or departments. The majority of studies gives no definition and no description of the practical execution of an episiotomy or describes it inadequately. To the current knowledge there is no international consensual definition, which is used universally. Until 2003, there was no study evaluating adequate implementation of the mediolateral episiotomy. It appears that most of executed mediolateral episiotomies are not truly mediolateral. The angle of inclination between 40-60 degrees was suggested. According to the latest study, the lower limit of the mediolateral episiotomy definition (40 degrees) appears to be insufficient. At the present time, the correlation between mediolateral episiotomy and perineal trauma cannot be precisely evaluated. Before analyzing the benefits and risks of mediolateral episiotomy, an international consensus must be found, that would establish an exact definition of mediolateral episiotomy.

Mathematical model of the male urinary tract.

The paper presents a simplified (but not trivial) mathematical model of the interaction between the urine flow and the male urethra and bladder, respectively. Urine is assumed to be a Newtonian fluid. The flow is considered to be non-stationary, isothermal and turbulent. The urethra and bladder wall, featuring elastic properties, experience large displacements and strains. The dynamic forces are included in the urethra wall motion. When fully extended the urethra attains the shape of an axisymetric tube. An iterative method based on the uncoupled approach is developed.