[The cultivation of cells on the porous titanium implants with the different structure].

The data on human dermal fibroblasts and rabbit mesenchymal stromal cells cultivation on porous titanium implants are presented in given paper. Two types of implants were used: type 1--with irregular pores formed by pressed titanium particles and type 2--with regular pores formed by coalescence of one-size titanium particles into implant. The goal of this study was to choose the type of titanium implant porosity which ensures the tightest interaction of titanium implant with surrounding tissue cells after implantation in the body. Cells were cultivated on implants for 7 days and in both cases they formed confluent monolayer on the implants surfaces. That indicated adhesion, migration and proliferation of cells on such implants. Condition of cells cultured on titanium implants was controlled by scanning electron microscopy. The character of fibroblasts interaction with given implants was different depending on porosity type of implants. On implants with irregular pores, the cells were more spread and overlapped the pores spreading over neighbored particles. On implants with regular pores that formed by one-size particles into implant, the fibroblasts covered these particles not overlapping the pores and seldom interacted with neighbored particles by small outgrowths. There was no tight interaction of particles into implant. In implants formed by pressed particles, the cells grew not only on the surface but also in the depth of implant. Thereby, we suppose that more tight interaction of cells with titanium implant and, supposedly, tissues with implant in an organism will take place in the case of implant structure formed by pressed titanium particles.

[Investigation of the tissue growth processes in porous implant].

Investigation of the cell (osteocytes, fibroblasts and keratinocytes) adhesion and penetration in pores of the titanium pylon in vivo on the laboratory animals (Wistar rats) has been performed. The titanium pylon has been implanted in bone of a rat's thigh residuum. Electronic scanning and morphological analysis demonstrated the certain integration of the pylon with the surrounding tissues. The latter opens a possibility for development of direct skeletal attachment of limb prostheses.

[Diagnostics and Express Orthesis in Children's Flat Foot.]. / Diagnostika a expres-ortézování pri ploché noze u detí

The method for diagnostics of flat foot in children at a specialized department for orthopaedic two-degree examination is described. The first degree consists in the very finding of flat foot, the second degree in the determination of the construction of the orthopaedic product with the subsequent express orthesis based on a module principle of devising orthopaedic insole. Key words: flat foot in children, modular orthesis.

What can normal gait biomechanics teach a designer of lower limb prostheses?

Compensating a limb loss with prosthesis is a challenging task due to complexity of the human body which cannot be fully matched by the available technical means. Designer of lower limb prostheses wants to know what specification of the device could provide the best approximation to the normal locomotion. Deep understanding of the latter is essential, and gait analysis may be a valuable tool for this. Once prosthesis is built, gait analysis may help in comparing the wearer's performance with the new device and with the prior art, and in verification of the hypotheses being put forward during the development process. In this lecture, we will discuss some synergies of normal gait. We will focus on the required biomechanical properties of a prosthetic leg that can allow the prosthesis's inclusion in normal gait synergy without demanding excessive compensatory movements. We will consider contribution of leg joints to generation of propulsion for adequate design of lower limb prostheses especially those with power supply.

Design features of implants for direct skeletal attachment of limb prostheses.

In direct skeletal attachment (DSA) of limb prostheses, a construct is implanted into an amputee's residuum bone and protrudes out of the residuum's skin. This technology represents an alternative to traditional suspension of prostheses via various socket systems, with clear indications when the sockets cannot be properly fitted. Contemporary DSA was invented in the 1990s, and several implant systems have been introduced since then. The current review is intended to compare the design features of implants for DSA whose use in humans or in animal studies has been reported in the literature.

Mechanical properties of totally permeable titanium composite pylon for direct skeletal attachment.

Composite pylons containing a solid titanium core with drilled holes surrounded by a porous sintered titanium shell have been fabricated and tested in bending along with the raw cores and pylons composed of the porous titanium alone. The new pylons were designed with the concept of enhanced in-growth of bone and skin cells and are intended for direct skeletal attachment of limb prostheses considering requirements for long-lasting anchorage to the residuum bone and a need for a safe skin-implant seal. Load-displacement thresholds were determined after which the integrity of the porous component may be compromised. The composite pylons have a flexural strength and stiffness substantially greater than that of pylons composed of the porous titanium alone. The drilled holes in the solid insert have been shown to have virtually no effect on the flexural strength of the pylon, while meeting a requirement for total permeability of the device for unrestricted cell ingrowth. The predicted strength of the pylons and associated failure modes are in close agreement with those measured.

Recording of electric signal passing through a pylon in direct skeletal attachment of leg prostheses with neuromuscular control.

Direct recordings were made of electrical signals emanating from the muscles in a rabbit's residuum. The signals were transmitted via wires attached on one end to the muscles, and on the other to an external recording system. The cable was held in a titanium tube inside a pylon that had been transcutaneously implanted into the residuum's bone. The tube was surrounded by porous titanium cladding to enhance its bond with the bone and with the skin of the residuum. This study was the first known attempt to merge the technology of direct skeletal attachment of limb prostheses with the technology of neuromuscular control of prostheses, providing a safe and reliable passage of the electrical signal from the muscles inside the residuum to the outside recording system.

Cell Cultivation on Porous Titanium Implants with Various Structures.

The paper presents data on the cultivation of human dermal fibroblasts and rabbit mesenchymal stromal cells on two types of porous titanium implants, i.e., those with irregular pores formed by pressed titanium particles and those with regular pores formed by the cohesion of one-size titanium particles inside the implant. The goal of this study was to determine what type of titanium implant porosity ensured its strongest interaction with cells. Cells were cultivated on implants for 7 days. During this period, they formed a confluent monolayer on the implant surface. Cells grown on titanium implants were monitored by scanning electron microscopy. Fibroblasts interaction with implants depended on the implant porosity structure. On implants with irregular pores cells were more spread. On implants with regular pores fibroblasts enveloped particles and were only occasionally bound with neighboring particles by small outgrowths. There was no tight interaction of particles inside the implant. In implants formed by pressed particles, cells grow not only on surface, but also in the depth of the implant. Thus, we suppose that a tighter interaction of cells with the titanium implant and, supposedly, tissues with the implant in the organism will take place in the variant when the implant structure is formed by pressed titanium particles, i.e., cellular interaction was observed inside the implant. In implants with irregular pores, cells grew both on the surface and in the depth. Thus, cells exhibited more adequate interactions with irregular pore titanium implants in vitro and hopefully the same interaction will be true in tissues after the implantation of the prosthesis into the organism.

Mathematical modeling of fixation of a bone fragment in a new Double-needle external Fixator compared to hoffmann ii fixator.

The outcome of rehabilitation after multiple bone fractures can be improved, and the reduction of the rate of amputation due to severe trauma can be achieved with the early use of external fixators [1, 2]. Effectiveness of the fixator depends on the stability of the bone fragments during the evacuation of a patient to specialized facilities [3, 4]. The paper is devoted to the mathematical modeling of the stability of a bone fragment in an external fixator. The vertical displacement of the end of a bone fragment loaded with a standardized force and moment is suggested to be the measure of stability. The finite element analysis (FEA) model developed has been applied to the new Double-Needle Ilizarov External Fixator (DNIF) [5], which does not penetrate the medullary canal, and to the Hoffmann II external fixator. Vertical displacement in DNIF (4.78·10-5m) obtained via FEA was approximately of one order smaller than in the corresponding Hoffmann II fixators (4.196·10-4m). The initial hypothesis has been confirmed that the stability of fixation with the DNIF was greater when compared to Hofmann II.

Study of Growth Processes in Bone and Skin Tissues in Porous Implants Designed for Fixation of External Prosthesis after Amputation of Extremities.

Modeling in vivo (on Wistar rats) was carried out by the method of complete integration of the prosthesis of an amputated extremity with a residuum; in this procedure the prosthesis is fixed to the residuum with a metal pylon one end of which is implanted into the bone of the residuum, while the other end traverses the residuum tissues and skin 5-7 cm above the residuum surface. This procedure includes not only successful implantation in the residuum bone, but also the possibility that the pores in the metal pylon can be filled with skin cells in the area of the pylon which traverses the tissues of the residiuum. The porous titanium pylon was implanted into the bone of experimental animals with amputated extremities. Penetration of bone and skin cells into the pores of the studied material was demonstrated, which provides tighter fixation in the bone and shows promise for the development of a natural cutaneous barrier to infection.

Amputee Hockey: Biomechanical Evaluations, Problems, and Paralympic Outlook.

The first ever ice hockey team of transtibial amputees playing in a standing position was established in St. Petersburg in 1999 under the program "US-Russian Prosthetic Rehabilitation Bridge" [1]. Nowadays, Canada, Russia, USA, Finland, Czech Republic and Latvia have their national associations, two World Championships were conducted (2003 - Kiisakalio, Finland; 2004 - Prague, Czech Republic), and the International Standing Ice Hockey Federation (ISIHF) was formed. Players from the former Yugoslav states, Estonia, Sweden, Israel, and Australia are very active in attempts to form the teams in their countries. Beyond the tournaments, players have participated in many professional conventions and other public events in support of international assistance to landmine victims and rehabilitation of children worldwide. The ISPO has been supportive in disseminating information and knowledge in amputee hockey, providing an opportunity for a demonstration game at the 2004 World Congress in Hong Kong (Figure 1).

Biomechanical evaluation of a prototype foot/ankle prosthesis.

In this paper, we report on our pilot evaluation of a prototype foot/ankle prosthesis. This prototype has been designed and fabricated with the intention of providing decreased ankle joint stiffness during the middle portion of the stance phase of gait, and increased (i.e., more normal) knee range of motion during stance. Our evaluation involved fitting the existing prototype foot/ankle prosthesis, as well as a traditional solid ankle cushioned heel (SACH) foot, to an otherwise healthy volunteer with a below-knee (BK) amputation. We measured this individual's lower extremity joint kinematics and kinetics during walking using a video motion analysis system and force platform. These measurements permitted direct comparison of prosthetic ankle joint stiffness and involved side knee joint motion, as well as prosthetic ankle joint moment and power.