Suturing methods in prolapse surgery: a biomechanical analysis.

INTRODUCTION: Pelvic organ prolapse is a common problem in urogynecological surgery. Abdominal and laparoscopic sacrocolpopexy is currently considered to be the gold standard of treatment. The main problem remains the anatomical point of fixation as well as how sutures are placed. We evaluated the biomechanical difference between an in-line ligament suture versus an orthogonal ligament suture and a single suture versus a continuous suture at the anterior longitudinal ligament in an in-vitro, sacrocolpopexy model. METHODS: Biomechanical in-vitro testing was performed on human, non-embalmed, female cadaver pelvises. An Instron test frame (tensinometer) was used for load/ displacement analysis. The average patient age was 75 years. Ligament preparation yielded 15 ligaments available for testing. Recorded parameters were the ultimate load, failure displacement, and stiffness. RESULTS: This in-vitro analysis of different suturing methods showed the difference between an orthogonal and an in-line approach to be the ultimate load. Orthogonal sutures displayed an ultimate load of 80 N while in-line suturing yielded only 57 N (p < 0.05). For the anterior longitudinal ligament, this study demonstrated that continuous suture is significantly superior to a single suture regarding failure displacement (p < 0.05). CONCLUSION: We established baseline biomechanical parameters for the sacrospinous ligament and anterior longitudinal ligament. An orthogonal suture is superior to an in-line suture in an in-vitro model. A continuous suture is superior to a single suture at the anterior longitudinal ligament. Clinical trials might be able to evaluate whether any clinical significance can be established from these findings.

Immediate dental and skeletal influence of distractor position on surgically assisted rapid palatal expansion with or without pterygomaxillary disjunction.

The outcome of surgically assisted rapid palatal expansion (SARPE) can be affected by pterygomaxillary disjunction (PMD) and the distractor position. In this study, SARPE was performed, with or without PMD, in 20 fresh cadaver heads. Transverse expansion was conducted twice using a bone-borne distractor in the anterior and posterior positions, resulting in four groups (n=10). Cone beam computed tomography scans were completed before and after SARPE to evaluate maxillary changes. A comparative anterior decrease and posterior increase in midpalatal opening resulted from SARPE with PMD combined with a posteriorly placed distractor. Significant differences in the internal transverse changes were found between the two SARPE techniques combined with an anterior distractor at the level of the premolars and molars for alveolar ridge width (P=0.040, P=0.024), and at the level of the molars for the dental crown width (P=0.017) and corresponding tooth cusp width (P=0.018). In contrast, using a posteriorly placed distractor led to a significant difference for tooth cusp width only (P=0.050). No statistically significant differences were found between external transverse changes or between distractor positions. PMD is more important in achieving a more uniform and parallel transverse expansion pattern than the distractor position. However, a posterior distractor seems to intensify the effects of PMD.

Changes in the temporomandibular joint position depending on the sagittal osteotomy technique and extent of mandibular movement.

The bilateral sagittal split osteotomy (BSSO) and high oblique sagittal split osteotomy (HSSO) are common techniques for mandibular movement in orthognathic surgery. The aim of this study was to evaluate the influence of both techniques, as well as movement distances and directions, on the position of the temporomandibular joint (TMJ). A total of 80 mandibular movements were performed on 20 fresh human cadaver heads, four on each head. Pre- and postoperative cone beam computed tomography was used to plan the surgical procedure and analyse the TMJ. Reference measurements included the anterior, superior, and posterior joint spaces, intercondylar distances and angles in the axial and coronal planes, and the sagittal, coronal, and axial angulations of the proximal segment. Only minor differences were found between the BSSO and HSSO techniques, particularly in terms of the intercondylar angle in the axial plane (P < 0.03) and the condylar angle of the proximal segment in the sagittal plane (P < 0.011). Observed changes in the TMJ were mostly opposite when moving the mandible forwards and backwards and increased with increasing movement distance. BSSO and HSSO result in similar changes in TMJ position. The extent of the movement distance influences the position of the condyle more than the osteotomy technique.

Improvement of anatomical knowledge and surgical skills in head and neck region - An interdisciplinary hands-on course for clinical students.

INTRODUCTION: Anatomical knowledge and manual skills are required for every surgical procedure. During the regular study the students only have few opportunities to practice their surgical skills actively. To improve this situation, an interdisciplinary hands-on-course for head and neck anatomy and surgery has been set up at the RWTH Aachen University. MATERIALS AND METHODS: The new course has been devised for one week with a full-time schedule. A special anatomical region has been studied each day. After an anatomical lecture, dissections under tutorial instructions took place. According to the anatomical region, a clinical lecture was given. Afterwards, surgical techniques were demonstrated and put into practice on fresh cadaver heads. To check the students' knowledge and the knowledge acquisition during the course, participants had to pass a pre- and post-test. The course was finished with an anonymous written evaluation of the course and an open feedback. RESULTS: The evaluations revealed a very high satisfaction of the students with the course. The post-test showed significant better results in anatomical and clinical knowledge than the pre-test. The mean result of the test was raised from 6.8 to 10.0 (p < 0.001) for the anatomical questions and from 5.9 to 10.5 (p < 0.001) for the clinical questions. CONCLUSION: The new interdisciplinary hands-on course is an effective method to consolidate anatomical knowledge and to link this awareness to a better understanding of head and neck surgery. The students improve their manual skills and get more interested and more open-minded for oral and maxillofacial surgery.

Laparoscopic pectopexy: a follow-up cyclic biomechanical analysis determining time to functional stability.

INTRODUCTION: Pectopexy, a laparoscopic method for prolapse surgery, showed promising results in previous transient testing by this group. It was shown that a single suture, yielding an ultimate load of 35 N, was equivalent to continuous suturing. This was demonstrated in an in vitro cadaver study. This transient data were used to establish an elastic stress-strain envelope. It was now possible to proceed to dynamic in vitro analysis of this surgical method to establish time to functional stability. METHODS: Cyclic testing of this fixation method was performed on human female embalmed cadaver (cohort 1) and fresh, non-embalmed cadaver (cohort 2) pelvises. The testing envelope was 5-25 N at a speed of 1 mm/s. 100 load regulated cycles were applied. RESULTS: 100 cycles were completed with each model; no overall system failure occurred. Steady state, i.e., functional stability was reached after 14.5 (± 2.9) cycles for the embalmed group and after 19.1 (± 7.2) cycles for the non-embalmed group. This difference was statistically significant p = 0.00025. CONCLUSION: This trial showed in an in vitro cyclic testing of the pectopexy method that functional stability may be achieved after no more than 19.1 cycles of load exposure. When remaining within the established load envelope of below 25 N, patients do not need to fear global fixation failure. Testing did demonstrate differences in non-embalmed and embalmed cadaver testing. Embalmed cadaver testing tends to underestimate time to steady state by 26.3%.

Evaluation of the lingual fracture patterns after bilateral sagittal split osteotomy according to Hunsuck/Epker modified by an additional inferior border osteotomy using a burr or ultrasonic device.

This study was conducted to compare fracture patterns and operation times after sagittal split osteotomy (SSO) by Hunsuck/Epker approach, performed using a burr or ultrasonic device, with and without osteotomy modification. A total of 80 SSOs were performed in fresh human cadavers using a burr or ultrasonic device to investigate the influence of surgical instruments as well as an additional bone cut on the inferior border of the mandible in terms of lingual fracture patterns. The times required for osteotomy and sagittal split were measured, and postoperative cone beam computed tomography images of all splits were analyzed. Without an additional inferior osteotomy, preferred splits according to Hunsuck/Epker were achieved in 35% of cases (7/20) with the burr and 45% (9/20) with the ultrasonic instrument. The inferior modification resulted in a greater number of unwanted fracture patterns in both groups. There was no relationship between the split technique and the fracture pattern (P=0.7854). Statistically significant differences in osteotomy time were observed between burr osteotomy and modified burr osteotomy (P=0.006), as well as modified ultrasonic osteotomy (P<0.001), but not between burr and ultrasonic surgery both without the inferior cut (P=0.36). The bone cut on the inferior border did not improve split control, but rather increased the risk of unwanted fractures and extended the operation time.

Suture button reconstruction of the central band of the interosseous membrane in Essex-Lopresti lesions: a comparative biomechanical investigation.

Surgical reconstruction of the interosseous membrane may restore longitudinal forearm stability in Essex-Lopresti lesions. This study aimed to compare the longitudinal stability of the intact forearm with a single-bundle and a double-bundle reconstruction of the central band of the interosseous membrane using digital image correlation with a three-dimensional camera system. Single and cyclic axial loading of eight fresh-frozen forearm specimens was carried out in the intact state, after creation of an Essex-Lopresti lesion, after a single-bundle and after a double-bundle reconstruction of the central band using a TightRope® (Arthrex GmbH, Munich, Germany) construct. Instability significantly increased after creation of an Essex-Lopresti lesion. The stability of intact specimens was similar to both reconstruction techniques. The results of this study suggest that TightRope® reconstruction of the central band restores longitudinal forearm stability. However, the single-bundle technique may be less reliable than double-bundle reconstruction. LEVEL OF EVIDENCE: Basic Science Study.

New approach for predictive measurement of knee cartilage defects with three-dimensional printing based on CT-arthrography: A feasibility study.

PURPOSE: The aim was to prove the possibility of creating an exact module of knee cartilage defects using 3D printing. METHODS: Defects were created in cadaver knees. CT-arthrography and 3-Tesla MRI were performed. Based on CTA images a model of the cartilage was created using 3D printing. Defect-sizes in the imaging modalities were compared. RESULTS: Estimated lesion area in 3D model differed approximately 5% comparing to the defect sizes in knees. MRI underestimated the defect on average of 12%, whereas the CTA overestimated the defect about 3%. CONCLUSIONS: We proved the feasibility of creating an accurate module of knee cartilage.

Radiofrequency-activated PMMA-augmentation through cannulated pedicle screws: A cadaver study to determine the biomechanical benefits in the osteoporotic spine.

INTRODUCTION: PMMA-augmentation of pedicle screws strengthens the bone-screw-interface reducing cut-out risk. Injection of fluid cement bears a higher risk of extravasation, with difficulty of application because of inconsistent viscosity and limited injection time. OBJECTIVE: To test a new method of cement augmentation of pedicle screws using radiofrequency-activated PMMA, which is suspected to be easier to apply and have less extravasations. METHODS: Twenty-seven fresh-frozen human cadaver lumbar spines were divided into 18 osteoporotic (BMD ≤ 0.8 g/cm2) and 9 non-osteoporotic (BMD > 0.8 g/cm2) vertebral bodies. Bipedicular cannulated pedicle screws were implanted into the vertebral bodies; right screws were augmented with ultra-high viscosity PMMA, whereas un-cemented left pedicle screws served as negative controls. Cement distribution was controlled with fluoroscopy and CT scans. Axial pullout forces of the screws were measured with a material testing machine, and results were analyzed statistically. RESULTS: Fluoroscopy and CT scans showed that in all cases an adequately big cement depot with homogenous form and no signs of extravasation was injected. Pullout forces showed significant differences (p < 0.001) between the augmented and non-augmented pedicle screws for bone densities below 0.8 g/cm2 (661.9 N ± 439) and over 0.8 g/cm2 (744.9 N ± 415). CONCLUSIONS: Pullout-forces were significantly increased in osteoporotic as well as in non-osteoporotic vertebral bodies without a significant difference between these groups using this standardized, simple procedure with increased control and less complications like extravasation.

Laparoscopic Pectopexy: A Biomechanical Analysis.

INTRODUCTION: Pectopexy, a laparoscopic method for prolapse surgery, showed promising results in recent literature. Further improving this approach by reducing surgical time may decrease complication rates and patient morbidity. Since laparoscopic suturing is a time consuming task, we propose a single suture /mesh ileo-pectineal ligament fixation as opposed to the commonly used continues approach. METHODS: Evaluation was performed on human non-embalmed, fresh cadaver pelves. A total of 33 trials was performed. Eight female pelves with an average age of 75, were used. This resulted in 16 available ligaments. Recorded parameters were ultimate load, displacement at failure and stiffness. RESULTS: The ultimate load for the mesh + simplified single "interrupted" suture (MIS) group was 35 (± 12) N and 48 (± 7) N for the mesh + continuous suture (MCS) group. There was no significant difference in the ultimate load between both groups (p> 0.05). This was also true for displacement at failure measured at 37 (± 12) mm and 36 (±5) mm respectively. There was also no significant difference in stiffness and failure modes. CONCLUSION: Given the data above we must conclude that a continuous suture is not necessary in laparoscopic mesh / ileo-pectineal ligament fixation during pectopexy. Ultimate load and displacement at failure results clearly indicate that a single suture is not inferior to a continuous approach. The use of two single sutures may improve ligamental fixation. However, overall stability should not benefit since the surgical mesh remains the limiting factor.

[Comparative ultrasonographic and histomorphologic examination of the lips]. / Vergleichende sonographische und histomorphologische Untersuchungen der Lippen.

BACKGROUND: High-resolution ultrasonography of the lips offers the opportunity to investigate the orbicularis oris muscle (OOM) and evaluate its morphology and function. OBJECTIVES: The goals of this paper are verification of the lip structures visible on ultrasound images by using histological section preparations and recommendation of uniform standards for sonographic examinations of the lips. MATERIALS AND METHODS: The lips of 78 healthy volunteers (age 4-77 years) where scanned with a Hitachi Hi Vision Avius ultrasound device equipped with a linear transducer (L75, variable frequency range 5.0-18.0 MHz). Systematic B-mode examination was performed at five defined points, and the lips where also scanned dynamically in multiple directions. The ultrasonography findings were verified by using histologic samples from five male body donors (age 72-83 years). RESULTS: All parts of the OOM could be well distinguished from one another both histologically and ultrasonographically. Sonographically visible lip structures could be verified histologically. Labial glands and blood vessels of the mucosa could be identified with both methods. CONCLUSION: Ultrasonography allows identification of lip structures and all parts of the OOM. Scars, injuries and atrophy of the lip musculature are well detectable. Functional examinations can visualize muscular dysfunctions and may support the diagnosis of dystonic or hypotonic functional deficits. The following parameters are mandatory for a standardized examination of the lips: sagittal and transverse images of upper and lower lips; use of anatomical "landmarks"; functional diagnostics in tensed and relaxed conditions.

PMMA-augmentation of incompletely cannulated pedicle screws: a cadaver study to determine the benefits in the osteoporotic spine.

BACKGROUND: Pedicle screw pullout due to poor bone quality, mainly caused by osteoporosis, is a common problem in spine surgery. Special implants and techniques, especially PMMA augmentation, were developed to improve the fixation of pedicle screws. PMMA injection into a pilot hole or through a screw involves the same risks as vertebroplasty or kyphoplasty, regardless of the technique used. Especially when using fully cannulated screws anterior leakage is possible. OBJECTIVE: To prove PMMA injection is safe and possible without leakage through an incompletely cannulated screw and also increases pullout forces in the osteoporotic vertebra. METHODS: Incompletely cannulated pedicle screws were tested by axial pullout in human cadavers, divided into osteoporotic and non-osteoporotic groups. Non-augmented and PMMA-augmented pedicle screws were compared. Twenty-five human vertebrae were measured by DEXA and divided into osteoporotic and non-osteoporotic groups. In each vertebra both pedicles were instrumented with the new screw (WSI-Expertise 6×45 mm, Peter Brehm Inc. Germany); the right screw was augmented with a 3 mL PMMA injection through the screw. On each screw axial pullout was performed after X-ray and CT scan. RESULTS: Radiographs and CT scans excluded PMMA leakage. Cement was distributed in the middle and posterior third of the vertebrae. Pullout forces were significantly higher after pedicle screw augmentation, especially in the osteoporotic bone. All augmented pedicle screws showed higher pullout forces compared with the unaugmented screws. CONCLUSIONS: We minimized the risk of leakage by using a screw with a closed tip. On the whole, PMMA augmentation through an incompletely cannulated pedicle screw is safe and increases pullout forces in osteoporotic bone to the level of healthy bone. Therefore the new incompletely cannulated screw can be used for pedicle screw augmentation.

The clivus: anatomy, normal variants and imaging pathology.

The clivus is one of the most central parts of the skull base. As diseases of the clivus evade clinical evaluation imaging plays a pivotal role in establishing a diagnosis. This article combines the description of anatomy and pathology with an extensive pictorial essay. Starting with the development and normal macroscopic anatomy of the clivus the reader is then introduced to a large variety of normal variations and developmental disorders some of them with clinical significance. Typical examples of non-neoplastic and neoplastic masses of the clivus and their differential diagnoses are provided. The article concludes with a review of inflammatory disease and trauma.

Effect of FTY720 treatment on postischemic pancreatic microhemodynamics.

CD4+ T cells contribute to disturbances of pancreatic microcirculation after cold and even after warm ischemia/reperfusion (I/R). The aim of this study was to investigate a possible protective role of FTY720 (fingolimod) in this setting. In an in vivo model (42 Wistar rats), ischemia of the pancreas was induced for 60 minutes under anesthesia with xylazin/ketanest. Sham-operated (SO) (I), untreated ischemic (II), and treatment group with FTY720 pre-treatment (1 mg/kg body weight i.v.) (III) were investigated. The effect of FTY720 on I/R injury was assessed by in vivo microscopy 30-90 minutes after reperfusion and by measurement of serum lipase. In the untreated ischemic group (II), capillary constriction to 85.3 ± 6.3% of SO diameters and a reduction of functional capillary density to 67% was found. After 30 minutes of reperfusion, the number of T cells in capillaries was increased (165.7%; P < .05 vs I). FTY720 pretreatment reduced this number to 54.2% of SO (P < .05 vs II). Likewise, the number of adherent leukocytes in capillaries (145.4 ± 11.2% of SO) was reduced in group III (109.3 ± 11.4%; P < .05 vs II), leading to an improvement in functional capillary density in the treatment group (98.2 ± 2% of SO; P < .05 vs II). According to improved microcirculation, lipase values were reduced in the therapy group (P < .05). In conclusion, FTY720 ameliorates the microcirculatory and biochemical manifestations of pancreatic I/R injury by preventing T-cell infiltration.

[Influence of disc prosthesis position on segmental motion in the lumbar spine]. / Einfluss der Position einer lumbalen Bandscheibenprothese auf das segmentale Bewegungsverhalten.

AIM OF THE STUDY: Total disc arthroplasty is reported to maintain segmental motion. From finite element studies a rather posterior and central implantation of the prosthesis is recommended. However, there is yet no in vitro study with cadaveric specimens investigating the topic of implant positioning. METHODS: Ten human lumbar spines were subjected to biomechanical testing. Flexion/extension and side-bending moments were applied from 2.5-7.5 Nm on a spine load simulator. First, the intact specimens were tested in 3 load cycles while motion was monitored with regard to the facet joints under different loads by an ultrasound-based system. An unconstrained total disc prosthesis was then implanted in a central position and the different load cycles were repeated. Finally the implant was positioned in a decentral position with an average offset of 6.2 mm for repetitive data acquisition. RESULTS: Comparison of the facet joint motion in central and eccentric prosthesis positions resulted in the following averaged differences. During flexion of the lumbar spine an average difference of the reference point excursions of 0.38 mm was recorded on the ipsilateral facet joint with reference to the decentral position. For extension, the difference was 0.33 mm on average, for right side bending a difference of 0.63 mm was recorded while left side bending resulted in an average difference of 0.24 mm. The deviation of the reference markers on the contralateral facet joint showed the following average differences: for flexion 0.23 mm and for extension 0.54 mm, respectively. For side bending right/left the differences amounted to 0.18 mm and 0.39 mm. With regard to segmental motion there was no statistically significant difference for both the ipsilateral (p = 0.0564) and the contralateral (p = 0.2593) reference marker. CONCLUSIONS: The comparison of the segmental motion after central and decentral implantation of a lumbar total disc prosthesis reveals differences that have, nevertheless, no statistical significance. However, for clinical use it is recommended to strive for a central position of the implant.

Haemorrhoids - a collagen disease?

OBJECTIVE: The cause of haemorrhoidal disease is unknown, epidemiological data and histopathological findings support the hypothesis that reduced connective tissue stability is associated with the incidence of haemorrhoids. Therefore the aim of this study was to analyse the quantity and quality of collagen formation in the corpus cavernosum recti in patients with III°/IV° haemorrhoids in comparison with persons without haemorrhoids. METHOD: Haemorrhoidectomy specimens of 31 patients with III°/IV° haemorrhoids were examined. The specimens of 20 persons who died a natural death and who had no haemorrhoidal disease served as the controls. The amount of collagen was estimated photometrically by calculating the collagen/protein ratio. The collagen I/III ratio served as parameter for the quality of collagen formation and was calculated using cross polarization spectroscopy. RESULTS: Patients with haemorrhoids had a significantly reduced collagen/protein ratio (42.2 ± 16.2µg/mg vs 72.5±31.0µg/mg; P= 0.02) and a significantly reduced collagen I/III ratio (2.0±0.1 vs 4.6±0.3; P<0.001) compared with persons without haemorrhoidal disease. There was no correlation with patients' age or gender. CONCLUSIONS: There is a fundamental disorder of collagen metabolism in patients with haemorrhoidal disease. It remains unclear whether this is due to exogenous or endogenous influences.

[Clinical anatomy of the temporal bone: taxonomy, topography and important variations]. / Klinische Anatomie des Os temporale : Systematik, Topographie und wichtige Variationen.

Detailed knowledge of the complicated anatomy and topography of the temporal bone is a crucial basis for successful ear surgery. In particular, the topographical relations to the essential neighbouring structures (e.g. intratemporal vessels and nerves, neighbouring spaces, especially the endocranium) are of vital importance. Furthermore, typical landmarks play an essential role in topographic orientation. However, this knowledge cannot be acquired from lectures or books, but can only be achieved by independently performing numerous dissections and drill exercises on the temporal bone, once a theoretical understanding of the various structures and regions has been gained on the basis of a clearly defined nomenclature. Furthermore, there are essential anatomical variations which may lead to complicated anatomical conditions. The surgeon must also be familiar with these peculiarities.

[Clinical anatomy of the paranasal sinuses. Descriptive anatomy, topography and important variations]. / Klinische Anatomie der Nasennebenhöhlen. Systematik, Topographie und wichtige Variationen.

Detailed knowledge of the complicated anatomy and topography of the paranasal sinuses is an essential requirement for successful surgery in this region. The topographical relationship to essential neighbouring structures (vessels, nerves and spaces) must be borne in mind. Typical landmarks play a particularly important role, especially for reliable orientation in endoscopic procedures. Therefore, it must be stressed that detailed anatomical knowledge of the complicated nasal and paranasal architecture is very important for the success of nasal and paranasal surgery, as well as for the avoidance of serious complications. However, this knowledge can only be acquired by performing numerous dissections of the nasal and paranasal system once a good theoretical grasp of the various structures, regions and their nomenclature has been gained. Common anatomical variations, which may lead to complicated and hazardous changes in normal anatomy, are also of particular importance and the surgeon must be familiar with these variations.

[Biomechanical analysis of lumbar spine after implantation of a disk prosthesis and supplementary spinal fusion for management of complications]. / Biomechanische Analyse der Lendenwirbelsäule nach Implantation einer Bandscheibenendoprothese sowie ergänzender Spondylodese als Komplikationsmanagement.

STUDY DESIGN: The aim of our investigations was to study the question as to what extent the mono- and multisegmental mobility of the lumbar spine (LS) differs after implantation of a disc prosthesis (DP) and if, in case of postoperative complications (dislocation or migration of the disc prosthesis), a sufficient stability of the motion segment can be achieved with a spinal fusion. To answer these questions we examined in corpse the mobility of the LS before and after DP implantation as well as after spinal fusion by using a load simulator for mobility and stability investigations of the lumbar spine. METHOD: After radiological exclusion of higher degenerative changes (X-ray in two planes) and exclusion of high-grade osteoporosis by using a pQ-CT scan with measurement of the bone mineral density (T score > -3.0), the first step was the multisegmental measurement of the thirteen unfixated LS specimens without DP by automatic electromechanical load-bearing. The measurements of mobility of the LS were done in flexion, extension, side-bending and side-rotation with a reproducible load of 10 Nm. The analysis of the movements during flexion and extension as well as side-bending and side-rotation were done by an ultrasonic detection system (zebris). In the second step the excursions were measured after implantation of the DP in L3/4 and in the third step after additional dorsal spinal fusion. RESULTS: After implantation of the artificial disc in L3/4 the mobility in side-bending and side-rotation increases in comparison to the LS without surgery. For side-bending we found an increasing amount up to +74 % for the single motion segment L3/4 and +3 % for the total LS, respectively, for the side-rotation an increase of mobility up to +72 % for the single motion segment L3/4 and +30 % for the total LS. On the other hand a decreased mobility of -11 % for flexion and extension was found with an artificial disc in comparison to the lumbar spine. After additional dorsal spinal fusion of L3/4 the mobility obviously decreases in all directions (flexion/extension -74 %, side-bending -75 %, side-rotation -51 %). CONCLUSION: The DP preserves (flexion/extension) and, respectively, improves (side-rotation/side-bending) the mobility of the LS. In cases of complications like dislocation or migration of the DP and secondary degenerative changes, the dorsal spinal fusion with restricted movements of the LS afterwards is a possible treatment solution.

Virtual reality-based simulator for training in regional anaesthesia.

BACKGROUND: The safe performance of regional anaesthesia (RA) requires theoretical knowledge and good manual skills. Virtual reality (VR)-based simulators may offer trainees a safe environment to learn and practice different techniques. However, currently available VR simulators do not consider individual anatomy, which limits their use for realistic training. We have developed a VR-based simulator that can be used for individual anatomy and for different anatomical regions. METHODS: Individual data were obtained from magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) without contrast agent to represent morphology and the vascular system, respectively. For data handling, registration, and segmentation, an application based on the Medical Imaging Interaction Toolkit was developed. Suitable segmentation algorithms such as the fuzzy c-means clustering approach were integrated, and a hierarchical tree data structure was created to model the flexible anatomical structures of peripheral nerve cords. The simulator was implemented in the VR toolkit ViSTA using modules for collision detection, virtual humanoids, interaction, and visualization. A novel algorithm for electric impulse transmission is the core of the simulation. RESULTS: In a feasibility study, MRI morphology and MRA were acquired from five subjects for the inguinal region. From these sources, three-dimensional anatomical data sets were created and nerves modelled. The resolution obtained from both MRI and MRA was sufficient for realistic simulations. Our high-fidelity simulator application allows trainees to perform virtual peripheral nerve blocks based on these data sets and models. CONCLUSIONS: Subject-specific training of RA is supported in a virtual environment. We have adapted segmentation algorithms and developed a VR-based simulator for the inguinal region for use in training for different peripheral nerve blocks. In contrast to available VR-based simulators, our simulation offers anatomical variety.