One of the main causes of cup loosening in cemented total hip replacement is the lack of a hydrolysis stable compound between the hydrophobic bone cement and the hydrophilic acetabular bone stock. ...Thus, the long-term adhesive strength between bone and bone cement is decreased resulting in premature aseptic loosening. Accordingly, an amphiphilic bonding system was developed to prevent hydrolytic debonding in the interface bone-to-bone cement.
Polyethylene cups were cemented in cadaver sheep hips. The hips were prepared with (n = 10) a multilayer bonding system as well as with an improved monolayer bonding system with (n = 10) and without (n = 10) UV-light hardening. The hips were dynamically loaded (10(6) cycles; 3 Hz; upper/lower load 1,500/200 N) and afterwards turned out with a defined strength to determine the interface compound strength. Dynamically loaded cemented cups without using the bonding system (n = 10) function as a control group.
The interface adhesive strength improved significantly by a factor of 1.9 (using the multilayer bonding system) compared to the unconditioned ones (P < or = 0.05); for the monolayer bonding system without (with) UV-light hardening the compound strength was 11.9-fold (> or =22.2-fold) higher (P < or = 0.001).
The bonding system significantly improves the adhesive strength between bone and bone cement in cemented cup arthroplasty.
Biodegradable segmented polyurethanes were prepared with poly(caprolactone) diol as a soft segment, 4,4′-methylene bis(cyclohexyl isocyanate) (HMDI) and either butanediol or dithioerythritol as chain ...extenders. Platelet adhesion was similar in all segmented polyurethanes studied and not different from Tecoflex® although an early stage of activation was observed on biodegradable segmented polyurethane prepared with dithioerythritol. Relative viability was higher than 80% on human umbilical vein endothelial cells in contact with biodegradable segmented polyurethane extracts after 1, 2 and 7 days. Furthermore, both biodegradable segmented polyurethane materials supported human umbilical vein endothelial cell adhesion, spreading, and viability similar to Tecoflex® medical-grade polyurethane. These biodegradable segmented polyurethanes represent promising materials for cardiovascular applications.
The goal of this study was to analyse the muscle strength of the cervical and lumbar spine in ironman triathletes. The values were compared to the results obtained from a reference group. The test of ...the triathletes was carried out in an attempt to define a specific strength profile for these athletes.
In this study, 20 long-distance triathletes (∅ 37.3 ± 7.6 years of age, ∅ 1.80 ± 0.1 m, ∅ 73.7 ± 6.0 kg) were evaluated with regard to their individual and sport-specific strengths of the cervical spine in 2 planes and of the trunk strengths in all 3 planes of motion. The trunk strength profile of the triathletes revealed good average results in the trunk extensors and the lateral flexors of the left trunk. The reference group is the data base of the company Proxomed®, Alzenau. It is based on results of 1045 untrained, symptom-free subjects of different ages.
Lumbar extension: The extension of the force values shows no significant difference from the reference group. Lumbar flexion: The flexion tests show highly significantly lower force values (5.025 ± 0.81 N/kg vs. 6.67 ± 0.6 N/kg) than the reference group. Flexion/extension: In the sagittal plane values for the triathletes demonstrate an imbalance in muscle strength ratios. The abdominal muscles turn in relation to the back extensor muscles too weakly to be very significant. Lumbar rotation: The force values of the athletes in both directions (right: 6.185 ± 1.46 N/kg, left: 7.1 ± 1.57 N/kg vs. 10.05 ± 0.34 N/kg) are highly significantly (p ≤ 0.001) lower than the reference values. Ratio of rotation left/right: The ratio of left/right rotation in the reference group is set at 1 and thus shows an equally strong force level between the two sides. Lumbar lateral flexion: The triathletes do not show any significant differences between the force values. Compared to the reference group there is no significant difference to the left side flexion. In the lateral bending the athletes have significantly better values than the reference group. Ratio of lateral left/right: In the reference group the ratio is set at 1. For triathletes, it shows an average value of 0.93. This difference is not significant. Cervical extension: The extension of the force values (1.96 ± 0.59 N/kg vs. 3.03 ± 0.24 N/kg) shows a highly significant difference from the reference group. Cervical flexion: In flexion (1.3 ± 0.42 N/kg vs. 2.17 ± 0.22 N/kg) triathletes have highly significantly lower strength values than the reference group. Flexion/extension: The triathletes did not differ significantly from the reference values (0.69 ± 0.23 and 0.72 ± 0.08). Lateral cervical spine: In comparison to the reference group (left: 1.67 ± 0.48 N/kg, right: 1.55 ± 0.46 N/kg vs. 2.36 ± 0.15 N/kg) in which there is left/right lateral flexion, there is a highly significant difference. Right lateral flexion is weaker than the left. Ratio of lateral left/right: The triathletes have a significant imbalance in the lateral flexion of the cervical spine compared to the reference group (1.07 ± 0.15 to 1).
In conclusion, in the triathlon there is a specific stress that is obviously not an adequate stimulus for the muscles of the cervical spine in order to achieve a balanced musculature and the athletes should be advised to practice a preventive approach with regard to these areas.
In this prospective study we present a novel technique of matrix-based chondrocyte transplantation for the treatment of focal cartilage defects.
22 patients with chondral or osteochondral femoral ...defects were treated with 3D-collagen type-I gel seeded with autologous chondrocytes (CaReS). Overall handling of this novel method is described, and results after 2 years follow-up with regard to the ICRS-score are presented.
14 patients were treated because of a focal chondral lesion, in 8 cases subchondral bone had to be reestablished. The average defect size was 6 cm(2). In all cases cell-seeded matrix samples could be fixed with fibrin glue without any problems. The average surgery time was 69 min, length of the surgical approach was 8.2 cm. No surgery-specific problems had to be observed. A significant improvement in IKDC-score, functional score and overall rating after 3 or 6 months up to 2 years follow-up was detected. After 2 years post-OP 13 Patients were evaluated and matrix-based defect treatment by CaReS was rated good to excellent by 84.6 % of the patients.
Defect treatment with cell-seeded 3D-collagen gel is easy to handle with a good clinical outcome after 2 years follow-up. Further investigations with higher patient number, longer follow-up time and histological and biomechanical sample analysis are needed in order to establish this method as an improvement of conventional ACT.
The aim of this study was to examine the clinical results after the treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte ...transplantation (ACT).
In this study 13 patients with osteochondral defects of the knee (12 femoral, 1 tibial) with OCD ICRS grade IV or ICRS grade IV B were included. The osteochondral defects were reconstructed simultaneously with autologous monocortical cancellous bone cylinders or chips from cancellous bone and matrix-supported autologous chondrocyte transplantation (CaReS). Data were analysed in accordance with the ICRS criteria and the Brittberg score. Patients were followed up to 36 months after the operation.
The average age of the patients was 34.9 (16 - 47) years at the time of surgery. The size of the defect was 8.1 (3.8 - 13.5) cm(2). The subjective and objective IKDC scores, the Brittberg and the ICRS function score were statistically significantly improved during the observation time. In one patient the transplantation failed and another patient was not available for the follow-up at 36 months. The objective IKDC score and the ICRS function score increased from 0/13 (0 %) to 11/12 (91.7 %) in categories A and B, or I and II, respectively, after 3 years. At this point of time 83.4 % (10/12) of the patients voted the treatment as excellent or good. The subjective IKDC score improved from 38.4 (+/- 12.7) preoperatively to 66.1 (+/- 17.0) after 3 years.
The treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation shows promising results even for larger defects. But for a final decision about this therapy the present sample size was too small. There is a need for further long-term investigation with a larger number of patients.
Picophytoplankton are vital components of the marine microbial food web. Being the smallest in the phytoplankton group, their short life cycles make them excellent bioindicators of environmental ...conditions. Given this, an investigation was conducted at the Kandla Port ecosystem (Latitude 23º 01' N; Longitude 70º 13' E) in the state of Gujarat, India to assess the response of picophytoplankton community structure to temporal and spatial environmental conditions. The sampling was conducted in July 2015, October-November 2015, and February 2016 at twenty-six stations. The results revealed a wide annual temperature range due to the study site's proximity to the Tropic of Cancer. The salinity ranged up to 40 while the turbulence caused by the macrotides resulted in highly turbid waters, especially during July due to precipitation. The picophytoplankton community was represented by picocyanobacteria (three sub-groups of Synechococcus) and picoeukaryotes (three sub-groups including Cryptophytes). The picocyanobacteria were abundant during the less turbid, warmer October-November period and lower during the cooler February period. The dominant Synechoccocus groups are associated positively with NH4+ and negatively with PO43-. The Cryptophytes were present during the warm and cool periods indicating tolerance to a wide range of temperature, salinity, and light. Their positive correlation with PO43- and NH4+ concentrations during February and October-November, respectively suggests a causal relationship. The picoeukaryotic group dominated the picophytoplankton community during the cooler period (February). The relative importance of the two picophytoplankton groups changed throughout the year exhibiting temporal niche segregation and hence establishing their role as bioindicators of temperature.
•Picophytoplankton community as bioindicators of temporal temperature variability.•Limited studies on their response in macrotidal turbid coastal ecosystems.•Synechoccocus dominant in warm period and picoeukaryotes in cooler period.•Two groups’ exhibited temporal niche segregation.•Cryptophytes tolerant to wide temperature, salinity, and light ranges.
The treatment of cartilage defects remains a major problem in orthopaedics. With regard to cartilage tissue engineering, the reimplantation of pre-cultivated chondrocytes in the form of a chondrocyte ...graft is a promising alternative to conventional methods. Clinical practice requires this MACT procedure (matrix-associated autologous chondrocyte transplantation) to produce a biocompatible replacement tissue with adequate mechanical properties. Mechanical stimulation has the capacity to improve the quality of these cell-seeded biomaterials. By altering chondrocytes' cellular activities, the biological and biomechanical properties of cartilage replacement tissue can be modulated. Different systems are used for this purpose, e.g. shear, perfusion, hydrostatic pressure or compression. The mechanisms, biological effects, chances and problems of the techniques are presented and assessed. Among the stimulating techniques considered are systems that apply indirect and direct shear forces such as spinner flasks, rotating-wall bioreactors, direct tissue shear and perfusion culture systems. The application of hydrostatic pressure or compression may be brought about by either static or dynamic loading systems. Compressive loading is considered in the light of both its short- and long-term effects; additionally two exemplified systems are discussed in detail. However, despite promising approaches and seemingly favourable tissue characteristics, the in vitro culturing of functional cartilage replacement tissue with cartilage-like mechanical and biological characteristics still remains elusive. Furthermore, controlling, monitoring and regulating culturing conditions are general biotechnological requirements of a standardised in vitro cultivation. Among these, different aspects such as aseptic operation, media supplementation, nutrient and gas exchange, temperature and humidity control are considered.
Collagen type-I matrix systems have gained growing importance as a cartilage repair device. However, most of the established matrix systems use collagen type-I of bovine origin seeded in high cell ...densities. Here we present a novel collagen type-I gel system made of rat tail collagen for the cultivation of human chondrocytes in low cell densities. Rat tail collagen type-I gel (CaReS, Arthro Kinetics, Esslingen, Germany) was seeded with human passage 2 chondrocytes in different cell densities to evaluate the optimal cell number. In vitro, the proliferation factor of low density cultures was more than threefold higher compared with high density cultures. After 6 weeks of in vitro cultivation, freshly prepared chondrocytes with an initial cell density of 2x10(5) cells/mL showed a proliferation factor of 33. A cell density of 2x10(5) cells/mL was chosen for in vitro and in vivo cultivation using the common nude mouse model as an in vivo system. Chondrocytes stayed viable as a Live/Dead fluorescence assay and TUNEL staining revealed. During in vitro cultivation, passage 0 cells partly dedifferentiated morphologically. In vivo, passage 0 cells maintained the chondrocyte phenotype and demonstrated an increased synthesis of collagen type-II protein and gene expression compared to passage 2 cells. Passage 2 cells did not redifferentiate in vivo. Cultivating a cell-seeded collagen gel of bovine origin as a control (AtelocollagenTM, Koken, Tokyo, Japan) did not lead to superior results with regard to cell morphology, col-II protein production and col-II gene expression. With the CaReS collagen gel system the best quality of repair tissue was obtained by seeding freshly isolated chondrocytes.
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