- MeSH
- Cortical Bone surgery MeSH
- Curettage * methods MeSH
- Humans MeSH
- Bone Neoplasms * surgery pathology secondary MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
BACKGROUND AND OBJECTIVES: Curettage is the removal of a tumor from the bone while preserving the surrounding healthy cortical bone, and is associated with higher rates of local recurrence. To lower these rates, curettage should be combined with local adjuvants, although their use is associated with damage to nearby healthy bone. OBJECTIVE: The purpose of this analysis is to determine the effect of local adjuvants on cortical porcine bone by using micro-computed tomography (micro-CT) along with histological and mechanical examination. METHODS: Local adjuvants were applied to porcine specimens under defined conditions. To assess changes in bone mineral density (BMD), a micro-CT scan was used. The pixel gray values of the volume of interest (VOI) were evaluated per specimen and converted to BMD values. The Vickers hardness test was employed to assess bone hardness (HV). The depth of necrosis was measured histologically using hematoxylin and eosin-stained tissue sections. RESULTS: A noticeable change in BMD was observed on the argon beam coagulation (ABC) sample. Comparable hardness values were measured on samples following electrocautery and ABC, and lowering of bone hardness was obtained in the case of liquid nitrogen. Extensive induced depth of necrosis was registered in the specimen treated with liquid nitrogen. CONCLUSION: This study determined the effect of local adjuvants on cortical bone by using micro-CT along with histological and mechanical examination. Phenolization and liquid nitrogen application caused a decrease in bone hardness. The bone density was affected in the range of single-digit percentage values. Liquid nitrogen induced extensive depth of necrosis with a wide variance of values.
This case study describes the experimental determination of displacements and stresses on a composite model of a pelvis that was modified to represent a healthy intact pelvic ring. The modified model was stressed statically up to 1750 N to simulate standing on one leg and also cyclically to model walking. For two different model settings in the loading machine the values of displacements and stresses at the pelvic ring were determined. The two different settings correspond to two different loading vectors applied on the pelvic ring, boundary conditions and degrees of freedom. The experimentally determined values of displacements in both settings are very similar and in accordance with the knowledge on the behaviour of a real human pelvis. The modified model is thus suitable for testing of newly developed implants for pelvis treatment and experimental determination of displacements and stresses in pelvic ring which are caused by application of implants.
- MeSH
- Biomechanical Phenomena MeSH
- Humans MeSH
- Pelvis * MeSH
- Pelvic Bones * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
AIMS: To assess the results of a biomechanical test of cadaveric specimens, comparing 2 methods of fixation of modified Lapidus arthrodesis in combination with arthrodesis of the first metatarsophalangeal joint. METHODS: A total of 12 cadaveric specimens were used in the test. Arthrodesis of the first MTP joint was in all patients fixed with a Variable Angle LCP 1st MTP Fusion Plate 2.4/2.7. Two methods of fixation of the Lapidus arthrodesis were compared, i.e. fixation with two screws in the PS (plate-screw) version versus fixation with X-Locking Plate 2.4/2.7 in the PP (plate-plate) version. Measurements were obtained with the use of a testing machine ZWICK Z 020-TND with an optical device Mercury RT for measuring deformities. Each specimen was subjected to 3 loading options, a. displacement 5 mm, the support is placed under the proximal phalanx, b. displacement 5 mm, the support is placed under the first metatarsal head and c. load to failure, the support is placed under the first metatarsal head. RESULTS: In all specimens the PS construct showed a statistically considerably higher stiffness than the PP construct. In all specimens treated with the PP construct the load to failure was lower than in the PS construct. For loading mode a., at a significance level of 0.05 (P<0.05), the P-value was 0.036, for mode b. the P-value was 0.007 and for loading mode c. the P-value was 0.006. In addition, age-related decrease in stiffness of the specimen was proved at a significance level of 5% (P=0.004). CONCLUSION: In all the three loading modes, the PS (plate-screw) construct showed a statistically higher stiffness than the PP (plate-plate) construct.
- MeSH
- Arthrodesis * methods MeSH
- Biomechanical Phenomena MeSH
- Bone Plates MeSH
- Humans MeSH
- Metatarsophalangeal Joint * surgery MeSH
- Cadaver MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: The purpose of this study was to evaluate the effectiveness between percutaneous and open pedicle screw fixation without fusion for treating type A3 and A4 thoracolumbar fractures. Traumatic thoracolumbar burst fracture is a common pathology without a consensus on the best treatment approach. Percutaneous pedicle screw fixation (PPSF) systems have been recently introduced in the treatment of spinal fractures to reduce the adverse effects associated with the conventional open approaches, such as iatrogenic muscle denervation and pain. METHODS: A prospective analysis was made to evaluate consecutive 46 patients with type A3 and A4 thoracolumbar fractures. Patients were divided into a percutaneous pedicle screw fixation group (PPSF) and an open pedicle screw fixation group (OPSF). The mean age of patients in PPSF group (12 men, 11 woman) was 49.9 years and in OPSF group (10 men, 13 women) 52.2 years. For the purpose of evaluation, the radiological assessment of the bisegmental Cobb angle, the loss of correction, the volume of blood loss, operation time, cumulative radiation time and dose were recorded and compared. RESULTS: All patients were followed up for 12 months. There were no significant differences between OPSF and PPSF in the Cobb angle preoperative and postoperative angle and the loss of bisegmental correction. In PPSF group, the mean preoperative Cobb angle was 10.9° and improved by 4.5° postoperatively, and in OPSF group the preoperative angle was 12.1° and postoperatively improved by 3.8°. Significant differences between OPSF and PPSF were found in the mean cumulative radiation time, radiation dose and operation time. PPSF group also had a significantly lower perioperative blood loss. CONCLUSIONS: Both open and percutaneous short-segment pedicle fixation were safe and effective methods to treat thoracolumbar burst fractures. Percutaneous fixation without fusion seems to be suitable for type A3 and A4 fractures.
- MeSH
- Lumbar Vertebrae injuries surgery MeSH
- Radiation Dosage MeSH
- Operative Time MeSH
- Adult MeSH
- Spinal Fractures surgery MeSH
- Thoracic Vertebrae injuries surgery MeSH
- Cohort Studies MeSH
- Blood Loss, Surgical MeSH
- Middle Aged MeSH
- Humans MeSH
- Minimally Invasive Surgical Procedures methods MeSH
- Young Adult MeSH
- Pedicle Screws * MeSH
- Prospective Studies MeSH
- Aged MeSH
- Fracture Fixation, Internal methods MeSH
- Treatment Outcome MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Randomized Controlled Trial MeSH
- Comparative Study MeSH
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
1 svazek : ilustrace ; 30 cm
Největším problémem totální endoprotézy (TEP) kyčle je aseptické uvolnění a periprotetická osteolýza, které jsou podmíněny typem a rychlostí otěru kloubních povrchů. Opotřebení není primární funkcí artikulačních materiálů, nýbrž důsledkem interakcí řady faktorů a podmínek. Tyto faktory a podmínky je možné dílem simulovat in vitro a studovat pomocí optické kolorimetrické interferometrie. Složení kloubní kapaliny, tlakové, rychlostní a další parametry experimentu budou vycházet z reálné situace. Proto je součástí navrhovaného projektu také analýza reálné kloubní kapaliny získané v průběhu reoperace/implantace TEP kyčle. Výstupy projektu budou využitelné při výrobě kloubních implantátů (materiálové a konstrukční inženýrství), při vysvětlení rozdílů v rychlosti opotřebení, přežití implantátu, resp. při pochopení biologických reakcí kolem TEP.; The main problem concerning total hip arthroplasty (THA) is aseptic loosening and periprosthetic osteolysis, both are related to the type and rate of joint surface wear. Wear is not a primary function of joint materials but is a result of the interaction of various factors and conditions. These factors and conditions can be simulated at least partially in vitro and analyzed using optic colorimetric interferometry. The composition of joint fluid, pressure, speed and other parameters of the experiment will evolve from the real situation. Therefore analysis of real joint effusions acquired during reoperation/ implantation of THA is part of the proposed study. Results of the project will be exploitable in the construction of joint implants (material and constructive engineering), in clarifying differences in wear rates, survival of implants, and also in understanding the biologic reactions around THA. Therefore, the proposed project is fully in accordance with the R&D program MH Czech Republic.
- MeSH
- Biocompatible Materials MeSH
- Colorimetry MeSH
- Hip Prosthesis MeSH
- Lubrication MeSH
- Arthroplasty, Replacement, Hip MeSH
- Surface Properties MeSH
- Reoperation MeSH
- Bone-Implant Interface MeSH
- Synovial Fluid MeSH
- Conspectus
- Ortopedie. Chirurgie. Oftalmologie
- NML Fields
- ortopedie
- NML Publication type
- závěrečné zprávy o řešení grantu IGA MZ ČR
STUDY DESIGN: An in vitro biomechanical study. PURPOSE: To evaluate the mechanical properties of the spinal segment in the intact, injured, and stabilized state after fixation by an Arcofix implant. OVERVIEW OF LITERATURE: Several types of thoracolumbar spine injury necessitates anterior instrumentation. The Arcofix plate represents the latest generation of angular stablity systems. The biomechanical properties of these implants have not been sufficiently studied yet. METHODS: A total of ten porcine specimens (levels Th12-L3) were prepared. The tests were performed for intact, injured, and implanted specimens. In each state, the specimen was subjected to a tension load of a prescribed force, and subsequently, twisted by a given angle. The force load was 200 N. The torsion load had a deformation character, i.e., the control variable was the twisting angle and the measured variable was the moment of a couple. The amplitude of the load alternating cycle was 3°. Another parameter that was evaluated was the area of the hysteresis loop. The area corresponds to the deformation energy which is dissipated during the cycle. RESULTS: A statistically significant difference was found between the intact and injured states as well as between the injured and implanted specimens. The statistical evaluation also showed a statistically different value of the hysteresis loop area. In the case of instability, the area decreased to 33% of the physiological value. For the implanted sample, the area increased to 170% of the physiological value. CONCLUSIONS: The Arcofix implant with its parameters appears to be suitable and sufficiently stable for the treatment of the anterior column of the spine.
- Publication type
- Journal Article MeSH
The aim of this study is to consider the relevance of in situ measurements of bovine serum film thickness in the optical test device that could be related to the function of the artificial hip joint. It is mainly focussed on the effect of the hydrophobicity or hydrophilicity of the transparent surface and the effect of its geometry. Film thickness measurements were performed using ball-on-disc and lens-on-disc configurations of optical test device as a function of time. Chromatic interferograms were recorded with a high-speed complementary metal-oxide semiconductor digital camera and evaluated with thin film colorimetric interferometry. It was clarified that a chromium layer covering the glass disc has a hydrophobic behaviour which supports the adsorption of proteins contained in the bovine serum solution, thereby a thicker lubricating film is formed. On the contrary, the protein film formation was not observed when the disc was covered with a silica layer having a hydrophilic behaviour. In this case, a very thin lubricating film was formed only due to the hydrodynamic effect. Metal and ceramic balls have no substantial effect on lubricant film formation although their contact surfaces have relatively different wettability. It was confirmed that conformity of contacting surfaces and kinematic conditions has fundamental effect on bovine serum film formation. In the ball-on-disc configuration, the lubricant film is formed predominantly due to protein aggregations, which pass through the contact zone and increase the film thickness. In the more conformal ball-on-lens configuration, the lubricant film is formed predominantly due to hydrodynamic effect, thereby the film thickness is kept constant during measurement.
- MeSH
- Adsorption MeSH
- Biomechanical Phenomena MeSH
- Hydrophobic and Hydrophilic Interactions MeSH
- Interferometry methods MeSH
- Hip Prosthesis * MeSH
- Lubricants chemistry MeSH
- Serum chemistry MeSH
- Cattle MeSH
- Wettability MeSH
- Materials Testing methods MeSH
- Animals MeSH
- Check Tag
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The objective of this paper is to briefly review the engineering biotribology of total hip arthroplasty (THA). At present the issue of lubrication, wear and friction within a THA is being studied in detail and the results have been published in a number of papers. The reason is obvious since the rate at which the articulating surfaces wear off affects the longevity of a THA to a great extent. Seeking an optimal biotribological configuration remains an important task for both the researchers and orthopaedic surgeons. In order to enable the orthopaedic community to think over THA biotribology and, at the same time, communicate with the representatives of technical professions, knowledge of the basic principles of biotribology and their understanding is necessary.
- MeSH
- Biomedical Engineering methods MeSH
- Hip Prosthesis * classification standards MeSH
- Humans MeSH
- Interdisciplinary Communication MeSH
- Arthroplasty, Replacement, Hip * instrumentation methods MeSH
- Surface Properties * MeSH
- Prosthesis Failure MeSH
- Check Tag
- Humans MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Review MeSH
The finite element analysis (FEA) has been identified as a useful tool for the stress and strain behaviour determination in lower limb prosthetics. The residual limb and prosthetic socket interface was the main subject of interest in previous studies. This paper focuses on the finite element analysis for the evaluation of structural behaviour of the Sure-flex™ prosthetic foot and other load-bearing components. A prosthetic socket was not included in the FEA. An approach for the finite element modelling including foot analysis, reverse engineering and material property testing was used. The foot analysis incorporated ground reaction forces measurement, motion analysis and strain gauge analysis. For the material model determination, non-destructive laboratory testing and its FE simulation was used. A new, realistic way of load application is presented along with a detailed investigation of stress distribution in the load-bearing components of the prosthesis. A novel approach for numerical and experimental agreement determination was introduced. This showed differences in the strain on the pylon between the experimental and the numerical model within 30% for the anteroposterior bending and up to 25% for the compression. The highest von Mises stresses were found on the foot-pylon connecting component at toe off. Peak stress of 216MPa occurred on the posterior adjusting screw and maximum stress of 156MPa was found at the neck of the male pyramid.
