[The angular profile of a cage has no influence on segmental alignment after anterior cervical stand-alone interbody fusion]. / Úhlový profil kose neovlivní segmentální postavení pri prední krcní fúzi provedené metodou stand-alone.

PURPOSE OF THE STUDY: The original aim of this prospective semi-randomised study was to determine associations between segmental sagittal alignment after Anterior Cervical Discectomy and Fusion (ACDF) and subjective and clinical results. Two types of cages, cage P with parallel end-plates and cage A with 5-degree angulations, were used in the patients treated for degenerative conditions. MATERIAL AND METHODS: A total of 94 consecutive patients, 56 treated by single-level ACDF and 38 undergoing a two-level procedure, completed 8 years of follow-up. The patients in equally-sized A and P subgroups were examined at 6 weeks and 1, 2 and 8 years after surgery. The follow-up included X-ray in a neutral lateral position, a questionnaire assessing pain in neck and shoulder regions and JOA scores. The results including the cumulative incidence of surgical procedures indicated for adjacent segment diseases were statistically evaluated. RESULTS: An average increase in the lordotic angle at 6 weeks after surgery was 2.32° for the implant P and 2.02° for the implant A subgroup. During 8 years of follow-up the average values decreased to 1.51° and 1.36°, respectively. The proportion of patients with no or minimal neck and shoulder pain decreased, in subgroup P, from the initial 85% at 6 weeks to 59% at 8 years after the surgery and, in subgroup A, from 89% to 40 %. The average JOA score of 16 at 6 weeks in both subgroups, at 8 years, had a value of 15.9 in subgroup P and 16.0 in subgroup A. The cumulative incidence of surgery for adjacent segment disease 8 years was 8.3% for subgroup P and 6.3% for subgroup A. No statistically significant differences between the subgroups at any follow-up period were recorded in either morphological characteristics or clinical outcomes. CONCLUSIONS: The ability to lordotize a segment by stand-alone ACDF is below the angular resolution of current radiographic methods, irrespective of the sagittal profile of the implant used. Comparable morphological results haven´t been reflected by significant difference in subjective and clinical outcome and also in the incidence of surgery for adjacent segment disease. Such results were not expected and therefore post-operative sagittal alignment mechanisms in stand-alone cage assisted ACDF will require further investigation. Key words:cervical vertebrae, surgical technique, spinal fusion, sagittal alignment, clinical outcome.

[Minimally invasive cervical elastic laminoplasty - principles and surgical technique]. / Minimálne invazivní krcní elastická laminoplastika - principy a operacní technika.

PURPOSE OF THE STUDY: To present a new technique of minimally invasive decompression of the cervical spinal canal using elastic and plastic deformation of the laminae. MATERIAL AND METHODS: Short midline vertical incision provides an access to the superior aspect of the target spinous processes. Cranial edge of the lamina is located by a midline, muscle-sparing interspinous dissection. The spinous process is cut in mid-sagittal plane using a thin blade of an ultrasonic bone scalpel down to epidural space. The created sagittal cleavage of the spinous process is subjected to tension and elastic distraction by a custom-designed distractor (Aesculap, Germany). Gradual increase of the distraction force leads to a significant plastic deformation. This reduces the distraction force and allows for a wider exposure which, in turn, facilitates dural visualization, resection of the yellow ligament and undercutting of approximately a half of the adjacent intact laminae. After completion of decompression, the plastic arch expansion can be maintained either by interposed bone-graft or appropriately shaped cage secured by a circumferential suture to the spinous process. Soft tissue resection and permanent expansion of the laminae provide sufficient decompression of the cervical spinal cord. In multilevel stenosis, the desired laminae can be expanded using this technique. To achieve the same degree of canal expansion as that by a classic laminoplasty (C3-7), a skip technique can be utilized. This involves combining expansive laminoplasty of C4 and C6 with bilateral undercutting of C5 and partial undercutting of C3 and C7. This can be achieved through two short vertical incisions. Based on data and experience gained from testing on 11 cadavers, we applied this method in 7 patients requiring posterior cervical decompression. RESULTS: The spinous process or laminae fractured during expansion in the initial 4 patients and the procedure required conversion to a minimally invasive laminectomy. Further modification of the distractor and spinous process splitting technique resulted in elimination of this complication in subsequent cases. In all remaining patients, sufficient canal expansion was achieved by soft tissue resection and distraction of laminae, typically reaching 5 - 8 mm. Minimally-invasive muscle-sparing midline approach provided very positive functional results in terms of postoperative pain and range of motion allowing for immediate mobilization without external bracing. CONCLUSION: Minimally invasive, muscle sparing, expansive laminoplasty provides adequate spinal canal expansion. Use of this technique and its muscle-sparing nature potentially result in improvement of early functional outcomes when compared to standard laminoplasty techniques requiring lateral lamina-facet border exposure. However, the theoretical superiority of this technique will need to be clinically scrutinized in a well designed surgical outcome study.

[Navigation techniques in surgery of cranio-cervical junction and upper cervical spine]. / Navigacní techniky v chirurgii kraniocervikálního prechodu a horní krcní pátere.

Spinal navigation has substantially advanced during the past ten years. Surgeons have gained sufficient skills and confidence, and have introduced this technology to the anatomically challenging region of the upper cervical spine and craniocervical junction. The detailed evaluation of individual anatomy, rational pre-operative planning and final intraoperative control improve the safety and precision of classical surgical procedures. As methods technologically evolve, indication criteria change accordingly, but the basic principles of a relevatn choice remain; these are to reduce morbidity due to its three main causes, i.e., mechanical, neurological and vascular. We present an overview of current techniques and discuss their applicability in the region of the upper cervical spine and craniocervical junction. The systems allowing us to obtain live images intra-operatively, such as fluoroscopy or intra.operative CT, seem to be most versatile and accurate, especially when combined with traditional virtual navigation systems. Based on case histories, the authors suggest trends in the development of this field, with a focus on minimally invasive techniques. Key words: navigation, upper cervical spine, craniocervical junction.

[Surgical treatment of fracture of the ring of axis - "hangman's fracture"]. / Chirurgické resení fraktury oblouku epistrofeu - "katovské zlomeniny".

PURPOSE OF THE STUDY: To evaluate surgical management of the fracture of the ring of axis (FRA), known as "hangman's fracture", and to discuss adequacy of this treatment. MATERIAL AND METHODS: Between 1994 and 2004, 41 patients with FRA were surgically treated in our hospital. We present a retrospective study of 30 cases treated by anterior cervical fixation and fusion and 11 cases treated by a posterior, CT-guided approach (published recently). Our diagnostic algorithm for evaluation of FRA included plain radiographs for basic diagnosis, detailed CT scan, MRI and finally passive lateral flexion-extension fluoroscopy (performed by physician) to assess stability. We also consider discography in selected cases, allowing further evaluation of discoligamentous injury. Fractures were classified according to Levine. Posterior compressive osteosynthesis according to Judet was performed in 11 patients with Levine type I fractures with fracture fragment distraction > 3 mm. Anterior graft and plate fixation was chosen in 30 patients with type II (25 patients) and type I (5 patients) fractures where C2/3 disc injury was confirmed by MRI or discography. There was no case of facet dislocation in our series (type III). Pain, motion restriction and overall satisfaction with neck status were assessed on a scale 1-5 (1 = best) in patients treated with anterior approach. Self-evaluation questionnaires were administered during follow-up (average, 7.3 years; 24 months to 11 years). RESULTS: Anatomically reduced fracture fusion was achieved in all cases (100%) at one year follow-up. Both autologous tricortical (22) and fibular allografts (8) were used for anterior approach. No perioperative complications occurred and no case was aborted. Average hospital stay in patients with standalone FRA was 6.8 days (3-15). Patients wore Philadelphia collar for 4-6 weeks. One patient died during follow up due to unrelated causes. None of the 29 patients treated with the anterior approach reported severe or very severe pain (grades 4 or 5). The average pain score was 1.28. Three patients with isolated FRAs reported slight subjective restriction of movement (grade 2). The "satisfaction with overall neck status" scale showed an average score of 1.62, never worse than grade 2. DISCUSSION: Despite increasing popularity of anterior surgical approach in the treatment of type II FRA, most authors still recommend conservative treatment. Surgical treatment is consensually recommended in type III fractures only. Type I is treated exclusively conservatively. There is currently no evidence-based data supporting any method of treatment of so called "hangman's fracture". The majority of treating surgeons do not consider the status of the intervertebral disc. Dynamic films, simulating the peak point of injury, are usually not performed. Hence, potentially unstable fractures are overlooked. This also explains the lack of long term follow-up data regarding the radiological status of C2/3 intervertebral disc as well as patients' subjective complaints. CONCLUSIONS: Surgery provides plausible results. Compared to conservative treatment, it can offer significant benefits: 1) immediate, better and stable reposition; 2) high fusion rate; 3) shortening of the treatment period with better quality of life. Contrary to conservative treatment modalities, surgery possesses a potential for further development.

Evaluation of the porous structures of new polymer packing materials by inverse size-exclusion chromatography.

A highly cross-linked porous polymer resin based on styrene-divinylbenzene matrix with pores created by the use of micellar imprinting technique was used as chromatographic packing material. Its performance as a column packing material in inverse size-exclusion chromatography was compared with a non-imprinted resin of the same polymer matrix. The porous structures (the pore size and the porosity) of the resins in the dry and wet states and their relationships with the elution volume of probe solutes (alkanes and polystyrene standards) were established. Characteristic properties of the resins such as specific pore volume, specific surface area and porosity are compared with results obtained by other methods of characterization such as mercury intrusion porosimetry, solvent regain and nitrogen sorption. The results show that the new porous resin can be used in the separation of small molecules. The separation is based on the size of the molecules, and the larger pores (meso- and macropores) in the porous resin can provide a much easier access to the smaller pores (micropores) which are useful in the chromatographic separations.

[Screening for venous thrombosis and pulmonary embolisms in patients with stroke using an adaptive classifier]. / Vyhledávání zilní trombózy a plicní embolie u nemocných s cévní príhodou mozkovou pomocí adaptivního klasifikátoru.

The use of adaptive linear neuron is referred to in recognizing veinous thromboses and lung embolism in a total of 88 acute palsies. As the input signs, the accessible clinical and laboratory data were used. Both training and adaptation of neuron have been performed in a part of total [35 patients], and 53 patients were submitted to the classification of patients with unknown distribution. In classified group with present complications, the screened diseases have been recognized in 16/20 patients. In 29 from 33 patients without thromboembolic states, the distribution by classificator appeared as correct one. The level of correct resolution was as high as 88% in all.

[A distraction abduction apparatus for treatment of Calvé-Legg-Perthes disease]. / Rozperný abdukcní aparát pro lécbu Calvého-Leggovy-Perthesovy choroby.

The authors submit to the orthopaedic public an abduction apparatus of their own desing for functional treatment of Calvé-Legg-Perthes disease. The apparatus is relatively simple, uses the pantographic system and during gait is preserves very satisfactory immersion of the head of the femur into the acetabulum. Contrary to the lumbal orthesis "Atlanta", it makes it possible to correct also anteversion in the hip joints. In the discussion the authors outline the contemporary therapeutic procedure of their department, the response to comments and finally the view of paediatrivians as regard treatment of the above disease.

Use of the adaptive classifier for determination of LD50 in the acute radiation disease.

In experiments on female Wistar rats a new method for the determination of LD50 is demonstrated and compared with the classical probit method using the same experimental animals. The method is applicable for the computation of LD50 and analogical quantities in man, too. The method is based on the application of an adaptive logical circuit (ADALINE) trained for the dichotomous prognostic classification of irradiated individuals quod vitam according to a set of clinical and laboratory indicators registered on the third day after irradiation. After the training procedure has been finished, the classifier makes possible an individual prognosis of survival or death. The analogue output signal according to which the classification is performed changes continually from negative to positive values and exhibits S-shaped relation to the radiation dose. Its zero value corresponds to the position of LD50 on the abscissa. For the construction of the searched function, i.e. for the optimum approximation of experimentally obtained values of the output signal, the method of the changeable polyhedron was applied belonging to the optimalization numerical methods used in the regulation technics. The computed value of LD50 was 7.80 Gy in rats very closely corresponding with the value 7.61 Gy determined by means of the classical probit method.

Intestinal absorption of tolfenamic acid at experimental malabsorption states in rats.

Absorption kinetics of 14C-labelled N-(3-chloro-o-tolyl)-anthranilic acid (tolfenamic acid, 14C-TA, Clotam) from the small intestine was studied in intact rats and in rats with malabsorption states provoked by methotrexate, starvation, and triparanol. 14C-TA was administered intravenously and intraduodenally, and the drug concentrations in the blood were followed up radiometrically. A multi-compartmental model was applied for mathematical analysis. Theoretical model parameters were computed, and absorption parameters were then derived from the theoretical ones. The absorption half-life of 14C-TA was 5.3 min in the controls, 10.8 min in the methotrexate-intoxicated, 7.5 min in the fasted, and 5.3 min in the triparanol-intoxicated rats. The absorbed fraction of the intraduodenal 14C-TA dose was 100% in each experimental group as well as in the controls. It is suggested that the slower transfer of 14C-TA through the intestinal barrier in the methotrexate-intoxicated and fasted rats may be caused by the reduction of the absorptive surface.

Computer recognition of gastric (pre)malignancy with the aid of some biochemical, immunological and cytological data.

17 patients with gastric pre-malignancy and 26 without it were correctly classified on the basis of the data from gastric juice (amount, pH, diphenylamine extinction, immunoglobulin A concentration, and total, parietal and surface epithelial cell counts) and from serum (immunoglobulin A concentration) using a kybernetic method of pattern recognition. The most decisive indices appear to be the diphenylamine extinction and immunoglobulin A concentration of gastric juice. Although X-rays, endoscopy and biopsy are the substantial diagnostic methods for gastric (pre-) malignancy a wide screening is desirable to recognize those people who are still asymptomatic but need the special examinations. We propose for this purpose a set of a few simple tests from blood serum and gastric juice, evaluated by method of pattern recognition.

Sex differences in the fate of N-methyl-14C-pethidine in rats.

N-Methyl-14C-labeled pethidine was administered intravenously to male and female rats at a dose of 1.25 mg per kg body weight. The amount of 14CO2 (originating from the N-methyl group) in the expired air of female rats was approximately a half of that expired by males. The amounts of radioactive metabolites (probably mainly deesterified products) in the excretions was higher in females. Pethidine levels in liver reach their maximum later, but attain substantially higher levels in females. The shapes of the curves relating pethidine levels to time are identical for blood and brain, but the brain levels are approximately ten times higher. Their course approximates a simple exponential curve in females, but a curve composed of two exponentials in males. Using the COMANSL computer programme and the data for blood levels, a three-compartment model has been established consisting of a central compartment 1, into which the drug was administered, a rapidly exchanging ("shallow") compartment 2, which is in equilibrium with 1, and a slowly exchanging ("deep") compartment 3, from which it is eliminated. Rate constants computed for the entry into and the exit from 1 were similar (0.23 and 0.22) in males; they could not be determined in females (possibly since they were too high). The passage from 1 to 3 was faster in males (0.07) than in females (0.04), the elimination from 3 was substantially faster in males (1.97) than in females (0.33). Faster demethylation in males is attributed to higher demethylation activity of male liver, known from in vitro experiments and faster rate of alternative pathways in females to higher substrate concentration in the liver. Attention is drawn to the considerable sex differences in the distribution of the drug.