Milan Handl

Novel composite hyaluronan/type I collagen/fibrin scaffold enhances repair of osteochondral defect in rabbit knee.

A new composite scaffold containing type I collagen, hyaluronan, and fibrin was prepared with and without autologous chondrocytes and implanted into a rabbit femoral trochlea. The biophysical properties of the composite scaffold were similar to native cartilage. The macroscopic, histological, and immunohistochemical analysis of the regenerated tissue from cell-seeded scaffolds was performed 6 weeks after the implantation and predominantly showed formation of hyaline cartilage accompanied by production of glycosaminoglycans and type II collagen with minor fibro-cartilage production. Implanted scaffolds without cells healed predominantly as fibro-cartilage, although glycosaminoglycans and type II collagen, which form hyaline cartilage, were also observed. On the other hand, fibro-cartilage or fibrous tissue or both were only formed in the defects without scaffold. The new composite scaffold containing collagen type I, hyaluronan, and fibrin, seeded with autologous chondrocytes and implanted into rabbit femoral trochlea, was found to be highly effective in cartilage repair after only 6 weeks. The new composite scaffold can therefore enhance cartilage regeneration of osteochondral defects, by the supporting of the hyaline cartilage formation.

Correlation of dynamic impact testing, histopathology and visual macroscopic assessment in human osteoarthritic cartilage

Objective Improved staging of cartilage degeneration is required, particularly during the early stages. We correlated mechanical properties with histological and macroscopic findings.MethodsOne hundred and twenty cartilage samples were obtained during total knee arthroplasty. Two adjacent plugs were harvested—one for histological classification and one for macroscopic and biomechanical purposes. Dynamic impact testing was performed; normal stress, dissipated energy (∆E), tangent modulus and stiffness were evaluated. Results Samples were classified according to six categories of the ICRS histological scale. Mechanical characteristics revealing significant differences between the groups (p < 0.01) were specific damping and related absolute ∆E. A significant correlation was found between the macroscopic score and specific damping, as well as absolute and relative ∆E (p < 0.01). A strong relation was revealed between relative ∆E and cartilage thickness (p < 0.001; R2 = 0.69). Conclusions Only ∆E correlated with the condition of the cartilage—the value increased with decreasing quality—and is the most suitable characteristic. This change appears substantial in initial stages of cartilage deterioration.

Clustering and separation of hydrophobic nanoparticles in lipid bilayer explained by membrane mechanics

Small hydrophobic gold nanoparticles with diameter lower than the membrane thickness can form clusters or uniformly distribute within the hydrophobic core of the bilayer. The coexistence of two stable phases (clustered and dispersed) indicates the energy barrier between nanoparticles. We calculated the distance dependence of the membrane-mediated interaction between two adjacent nanoparticles. In our model we consider two deformation modes: the monolayer bending and the hydroxycarbon chain stretching. Existence of an energy barrier between the clustered and the separated state of nanoparticles was predicted. Variation analysis of the membrane mechanical parameters revealed that the energy barrier between two membrane embedded nanoparticles is mainly the consequence of the bending deformation and not change of the thickness of the bilayer in the vicinity of nanoparticles. It is shown, that the forces between the nanoparticles embedded in the biological membrane could be either attractive or repulsive, depending on the mutual distance between them.

Osteoarthritis of the Ankle

The chapter is focused on the degenerative processes that may appear in the ankle joint. It concerns either changes followed after the injury, isolated focal lesions, degenerative changes, or secondary reasons for the development of osteoarthritis (OA). Anatomy and clinical signs are described for the principal evaluation of the configuration and symptoms that are present in OA. Diagnosis of OA is done by comprehensive evaluation of clinical, X-ray, MRI, and possible CT scan findings. Conservative treatment is comparable to other big joints. The operation treatment options consist of arthroscopy, miniinvasive surgery, arthrodesis, and total joint replacement. Their indications and examples are given.

Retrieval of New Characteristic Features for Description of Cartilage Tissue Properties Using Blunt Impact Testing Approach

Investigation of joint cartilage properties is of prime importance due to facilitation of its routine diagnostics and artificial tissue engineering. This experiment is based on our previous work in which we have developed new technique for dynamic testing of cartilage tissue biomechanical properties using blunt impact approach. Obtained data are confronted with ICRS histological classification of examined knee cartilage samples.