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The transcostal closure technique of intercostal thoracotomy closure appears to be associated with less pain in the first 24 hours and could be an alternative to the standard circumcostal technique. The goal of this study was to compare the ex vivo biomechanical properties of three suture techniques for intercostal thoracotomy closure. Samples of porcine ribs were used for the research. A 10 cm incision was made in the intercostal space in each sample. The techniques compared were: simple circumcostal interrupted suturing, continuous circumcostal suturing, and interrupted transcostal suturing. During the testing in the machine, suture rupture or rib cracking occurred. If rib cracking occurred first, the testing was continued until the suture broke as well. In the first group, rib fracture occurrence was 60% and suture rupture was 40%. In the second group, rib fracture occurrence was 55%, while 45% of the samples failed by suture rupture. In the third group, rib fracture occurrence was 70%, while suture rupture was 30%. These data did not differ significantly between groups (P>0.05). Continuous circumcostal suturing took the least amount of time, and the most time-consuming technique was interrupted transcostal suturing. Simple circumcostal suturing used most material, and the least amount of material was used with continuous circumcostal suturing. The conclusion of this paper is that the continuous pattern suture has the same mechanical strength as the other two suture patterns, but it consumes the least time and material. Therefore, from a mechanical standpoint, we advise the use of continuous circumcostal suture for intercostal thoracotomy closure., Doima se da je interkostalna tehnika zatvaranja torakotomije povezana s manje bola unutar prva 24 sata te bi mogla bi biti alternativa standardnoj cirkumkostalnoj tehnici. Cilj ovog istraživanja bio je usporediti ex vivo biomehanička svojstva triju tehnika za zatvaranje interkostalne torakotomije. Za istraživanje su korišteni uzorci svinjskih rebara. Na svakom je uzorku učinjena incizija duga 10 cm. Uspoređivano je jednostavno cirkumkostalno pojedinačno šivanje, produžno cirkumkostalno šivanje i pojedinačno transkostalno šivanje. Tijekom testiranja na trgalici popuštali su šavovi ili je došlo do loma rebara. Ako je došlo do loma rebara, testiranje je nastavljeno do popuštanja šavova. U prvoj skupini lom rebara dogodio se na 60 % uzoraka, dok je u 40 % uzoraka popustio šivaći materijal. U drugoj skupini u 55 % uzoraka popustila su rebra, dok je u 45 % uzoraka popustio šivaći materijal. U trećoj skupini u 70 % uzoraka popustila su rebra, dok je u 30 % slučajeva popustio šivaći materijal. Ovi se podaci ne razlikuju znakovito među testiranim skupinama (P > 0,05). Produžnim cirkumkostalnim šivanjem utrošak vremena bio je najmanji, dok je pojedinačnim transkostalnim šivanjem utrošak vremena bio najveći. Jednostavnim cirkumkostalnim šivanjem utrošilo se najviše šivaćeg materijala, dok je najmanje materijala utrošeno produžnim cirkumkostalnim šivanjem. Zaključak ovog rada je da produžno šivanje pruža jednaku mehaničku snagu kao i ostale testirane metode, ali je utrošak vremena i materijala manji. Stoga, s mehaničkog stajališta, za zatvaranje interkostalne torakotomije preporučujemo jednostavni cirkumkostalni šav.

Numerical analysis is carried out for a frictionless receding contact problem of a perfect-fit pin and bushing in a uniaxially loaded plate. The problem is analysed using the finite element method under the assumption of plane strain and linear elasticity. The problem is investigated for the influence of external load and for different geometries. The obtained contact pressures show uncharacteristic behaviour, where higher peak values occur on contact surfaces with larger contact angles. This seemingly contradicts not only the physics of receding contact problems, but also the physical laws of contact problems in general. It is shown that the reason for this unusual behaviour is, in fact, in the physical reduction of the contact area as the radius of curvature decreases. This class of problems shows to be linearly dependent on the intensity of load as regards the contact stresses, and load has no influence on the contact angles.

The aim of the study was to assess the influence of gap shape on biomechanical results in extra-articular distal humeral fracture: with contact on the posterior part (by anterior gap) and contact on ulnar column (by radial gap). The goal was to examine if and to what extent did displacements decrease in comparison with previously examined parallel gap without bony contact. The finite element analysis on the three different plate constructs was performed, i.e. parallel, perpendicular and newly designed Y shape plate were considered. Displacements were measured on articular surface and gap point. The most visible decrease of maximum displacements in the distal part of the model was detected in the Y plate model with axial loading: in case of anterior gap 58.5% and especially at radially formed gap 60.9%. Similarly, at axial loading, displacement at the analyzed point on fracture gap most significantly decreased in Y plate model (by 49.4%) at posterior bony contact. Moreover, the latter showed displacement decrease by 68.5% at ulnar bone contact. Furthermore, if a longer radial plate than the ulnar one was used, varus stress could have been avoided. Study results suggested that sufficient stability could be ensured with the newly designed Y shape plate., Cilj ovoga rada bio je procijeniti utjecaj oblika pukotine na biomehaničke rezultate kod extraartikularnih prijeloma distalnog humerusa s kontaktom na stražnjem dijelu (procijepom u prednjem dijelu) i s kontaktom na ulnarnoj kolumni (procijepom na radijalnom dijelu). Cilj je bio ispitati smanjuju li se i u kojoj mjeri pomaci u usporedbi s prethodno ispitanim paralelnim procijepom bez koštanog kontakta. Provedene su računalne simulacije metodom konačnih elemenata na modelima s paralelnom i perpendikularnom konfiguracijom rekonstrukcijskih pločica i s novodizajniranom Y pločicom. Mjerenja su izvršena na zglobnoj plohi i u mjernoj točki na distalnom rubu pukotine. Najizraženije smanjenje maksimalnih pomaka bilo je kod Y ploče pri aksijalnom opterećenju s procijepom u prednjem dijelu (58,5%), a osobito s radijalnim procijepom (60,9%). Slično, pri aksijalnom opterećenju smanjenje pomaka u analiziranoj točki na frakturnoj pukotini bilo je najizraže nije kod Y pločice (49,4%) s dorzalnim kontaktom i ulnarnim koštanim kontaktom (68,5%). Kako bi se izbjegla varusna naprezanja, radijalna ploča treba biti duža od ulnarne. Studija ukazuje na to da se dostatna stabilnost može osigurati novodizajniranom Y pločicom.

Vanjski fiksatori koriste se za liječenje otvorenih i zatvorenih prijeloma dugih kostiju. Krutost i čvrstoća fiksatora uvelike utječu na konačan ishod liječenja. Odgovarajuća stabilnost koštanih ulomaka omogućuje bolje cijeljenje prijeloma i bržu rehabilitaciju pacijenta. Cilj ovog istraživanja bila je procjena biomehaničke stabilnosti novokonstruiranog unilateralnog vanjskog fiksatora za prijelome proksimalne tibije. S ciljem usporedbe svojstava prototipa novog fiksatora s vanjskim fiksatorom Orthofix, koji se često upotrebljava u kliničkoj praksi, provedena su statička i dinamička ispitivanja. Pri statičkom ispitivanju uzorci su opterećeni aksijalno i na savijanje, a pomaci su određeni bezkontaktnim optičkim mjernim sustavom Aramis. Rezultati su pokazali da su biomehanička svojstva nove konstrukcije bolja kod savijanja, dok se konvencionalni vanjski fiksator pokazao boljim pri aksijalnom opterećenju. Pri cikličkom ispitivanju nije bilo značajne razlike u rezultatima., External fixators are used to treat open and closed fractures of long bones. Stiffness and strength of the fixator greatly affect the final outcome of treatment. An adequate stability of bone fragments provides better fracture healing and early rehabilitation of patients. The aim of this study was to evaluate biomechanical stability of the newly developed unilateral external fixator for proximal tibial fractures. In order to compare the properties of the prototype of the novel fixator and commonly used external fixator Orthofix, static and dynamic tests were conducted. Two different types of static tests were carried out, axial compression test and bending test. In static tests displacements were measured and calculated by using the non-contact optical measuring system Aramis. The results indicated that the novel fixator has better outcomes in bending, while the conventional fixator outperformed the new one in axial compression. There was no significant difference in cyclic test.

Background and Purpose: Human walking has been extensively studied by many investigators and numerous mathematical models of lower limb movements have been developed but few reports have been written about contribution of the upper limbs to the locomotion process. The aim of this study was to investigate the influence of walking speed and effect of the upper limb swing on the trajectory of the whole body mass center, as well as on ground reaction forces during human walking. Material and Methods: An automatized method for determination of the whole body mass center has been established. Gait analysis was performed on 52 subjects using the Elite system and Kistler force platform. The recording of trajectories of characteristic body points on subjects and measurement of ground reaction forces were performed at normal speed walking with natural and emphasized rhythmic upper limb swing and at fast walking speed. The determined mean values of normalized components of trajectory of the body mass center and ground reaction forces were compared. Result and Conclusion: The study showed that components of ground reaction forces and trajectory of the whole body center of mass are influenced by changes in arm swing and gait velocity. Maximum magnitudes of components of ground reaction force increased for normal speed walking with emphasized upper limb swing. The emphasized upper limb swing decreased the magnitude of vertical oscillations of the body center of mass and thus may influence energy expenditure.

Background and Purpose: Human walking has been extensively studied by many investigators and numerous mathematical models of lower limb movements have been developed but few reports have been written about contribution of the upper limbs to the locomotion process. The aim of this study was to investigate the influence of walking speed and effect of the upper limb swing on the trajectory of the whole body mass center, as well as on ground reaction forces during human walking. Material and Methods: An automatized method for determination of the whole body mass center has been established. Gait analysis was performed on 52 subjects using the Elite system and Kistler force platform. The recording of trajectories of characteristic body points on subjects and measurement of ground reaction forces were performed at normal speed walking with natural and emphasized rhythmic upper limb swing and at fast walking speed. The determined mean values of normalized components of trajectory of the body mass center and ground reaction forces were compared. Result and Conclusion: The study showed that components of ground reaction forces and trajectory of the whole body center of mass are influenced by changes in arm swing and gait velocity. Maximum magnitudes of components of ground reaction force increased for normal speed walking with emphasized upper limb swing. The emphasized upper limb swing decreased the magnitude of vertical oscillations of the body center of mass and thus may influence energy expenditure.

The aim of this study was to investigate the influence of the upper limb swing on human gait. Measurements were performed on 52 subjects by using the Elite system with two cameras and a Kistler force platform. The recording of trajectories of characteristic body points on the subjects and the measurement of ground reaction forces have been performed at normal walking and at walking with emphasised rhythmic upper limb swing. The trajectory of the whole body mass centre, central dynamic moments of inertia and ground reaction forces have been calculated for every subject and mean curves of the entire group have been determined for walking with the natural and the emphasised upper limb swing. The determined mean values of normalised mechanical parameters have been compared and differences between the gait with the natural and the emphasised upper limb swing have been described.