Određivanje stabilnosti novog vanjskog fiksatora primjenom mjernog sustava Aramis

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

COMPUTER REPRESENTATION OF OSTEOSYNTHESIS STABILITY IN LOCKING PLATES USED FOR THE TREATMENT OF OSTEOPOROTIC PROXIMAL HUMERUS FRACTURES

Background: Proximal humerus fractures are represented as 4-5% of all fractures, with incidence notably growing with age. Since surgical internal fixation in treatment of proximal humeral fractures is used, fractures of osteoporotic bone and choice of plate for their osteosynthesis represent particular problem. The aim of the study was to test two locking plates: Philos plate with locking screws with determinated direction, and Arthrex plate with poliaxial locking screws, using the finite element method. Subjects and methods: This study used version 6.10 of Abaqus FEA software package for simulation and fine element analysis of Philos and Artrex plates attached to the osteotomy models of proximal humerus with fracture gap at 0°, 10° and 20° in four types of static load: abduction, adduction, axial compression and flexion. Simulation results of loads in abduction, adduction, axial loads and flexion, were described with the total bone displacement (U) and maximum bone displacement in the fracture gap (Uf ). Results: When examining the Philos plate in axial load on the bone with fracture gap angle from 0°, 10° and 20° no significant differences between the results for the displacements were observed. Therefore, results for other loads are related to total displacements of the bone only at the angle of 0°. Given that the results of the total bone displacement and maximum bone displacement in the fracture gap with Artrex plate were mostly higher, for comparison with the results of bone displacement in Philos plate it was taken that total bone displacement and maximum displacement in the fracture gap in Artrex plate represent 100% of the total displacement. Philos plate showed 60.71% for abduction, 76.07% for adduction, 102.24% for axial loads and 79.59% for flexion of total bone displacement in Artrex plate, and 60.48% for abduction, 76.07% for adduction, 96.05% for axial load and 79.96% for flexion of maximum displacement in the fracture gap in Artrex plate. Conclusions: Osteosynthesis for osteoporotic fractures of proximal humerus with Philos plate in computer simulation proved to be more stable than with Arthrex plate

THE RESULTS OF INTERNAL FIXATION OF PROXIMAL HUMERAL OSTEOPOROTIC FRACTURES WITH PHILOS LOCKING PLATE

Background: In the last fifty years since plate and screw osteosynthesis has been implemented in fracture treatment, osteosporotic bone fractures were observed as a special problem. Due to special histologic, anatomic, physical and biomehanic properties of osteoporotic changed bone the laws of biomechanics suggest that stable osteosynthesis for osteoporotic bone is necessary to increase the contact surface of metallic implants and bone and the stability of the screw-plate-bone compound. There are numerous surgical techniques and methods for treatment of osteoporotic proximal humeral fractures. Every surgical procedure has to establish anatomical reduction and stable fixation that will enable early mobilisation. Subjects and methods: The aim of this study was to present results of internal fixation of proximal humeral osteoporotic fractures with PHILOS locking plate. Between 2007 and 2012, a total of 67 patients older than 65 years with closed proximal humerus fractures underwent surgical treatment with PHILOS plate system (Synthes, Switzerland). 42 patients were operated with deltopectoral approach and 25 with deltoid split approach. After a mean follow up period of 14.68 (6-28) months functional and radiologic results were assessed. Results: We noted 9 postoperative complications related to surgical technique (1 intraarticular screw placement, 1 displacement in major tuberculum fragment, 1 displacement in major tuberculum fragment along with oblique placement of the plate, 2 cases of inadequate reduction, 1 case of humeral head avascular necrosis, varus humeral head fixation in 3 cases). None of the patients developed superficial or deep surgical infection. There was no nonunions. In the final evaluation, the Constant shoulder score was 91.75 (72-100). Conclusions: In this study PHILOS locking plate showed good applicability, respecting bone biologic properties because of negligible interference with blood supply of the humeral head. There was no requirement to shape the plate enabling stabilization at constant angles as clear benefit of this plate. All that enables early mobilisation, and no implant insufficiency resulting in satisfactory treatment results and high Constant shoulder scores

Determining the stability of novel external fixator by using measuring system Aramis

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

THE RESULTS OF INTERNAL FIXATION OF PROXIMAL HUMERAL OSTEOPOROTIC FRACTURES WITH PHILOS LOCKING PLATE

Background: In the last fifty years since plate and screw osteosynthesis has been implemented in fracture treatment, osteosporotic bone fractures were observed as a special problem. Due to special histologic, anatomic, physical and biomehanic properties of osteoporotic changed bone the laws of biomechanics suggest that stable osteosynthesis for osteoporotic bone is necessary to increase the contact surface of metallic implants and bone and the stability of the screw-plate-bone compound. There are numerous surgical techniques and methods for treatment of osteoporotic proximal humeral fractures. Every surgical procedure has to establish anatomical reduction and stable fixation that will enable early mobilisation. Subjects and methods: The aim of this study was to present results of internal fixation of proximal humeral osteoporotic fractures with PHILOS locking plate. Between 2007 and 2012, a total of 67 patients older than 65 years with closed proximal humerus fractures underwent surgical treatment with PHILOS plate system (Synthes, Switzerland). 42 patients were operated with deltopectoral approach and 25 with deltoid split approach. After a mean follow up period of 14.68 (6-28) months functional and radiologic results were assessed. Results: We noted 9 postoperative complications related to surgical technique (1 intraarticular screw placement, 1 displacement in major tuberculum fragment, 1 displacement in major tuberculum fragment along with oblique placement of the plate, 2 cases of inadequate reduction, 1 case of humeral head avascular necrosis, varus humeral head fixation in 3 cases). None of the patients developed superficial or deep surgical infection. There was no nonunions. In the final evaluation, the Constant shoulder score was 91.75 (72-100). Conclusions: In this study PHILOS locking plate showed good applicability, respecting bone biologic properties because of negligible interference with blood supply of the humeral head. There was no requirement to shape the plate enabling stabilization at constant angles as clear benefit of this plate. All that enables early mobilisation, and no implant insufficiency resulting in satisfactory treatment results and high Constant shoulder scores

Is experimentally induced pain associated with socioeconomic status? Do poor people hurt more?

BACKGROUND: The association of pain and socioeconomic status is widely reported, yet much less clearly understood. The aim of this study was to investigate the association of experimentally induced pain threshold and tolerance with socioeconomic status. ----- MATERIAL/METHODS: The study sample consisted of 319 adult subjects from the population of the island of Vis, Croatia, which was previously shown to have a high level of social homogeneity. A manual dolorimeter was used to measure mechanical pressure pain threshold (least stimulus intensity) and pain tolerance (maximum tolerance stimulus intensity) on both hands. Pain tolerance interval was defined as the difference between pain tolerance and threshold. Years of schooling and material status were used as socioeconomic estimates. ----- RESULTS: Both of the socioeconomic estimates were significantly correlated with pain threshold, tolerance, and tolerance interval (P<0.001). The mixed modeling analysis, controlled for the effects of age, gender, and 4 psychological variables, indicated that education was not a significant predictor in any of the 3 models. However, lower material status was significantly associated with lower pain tolerance (P=0.038) and narrower pain tolerance interval (P=0.032), but not with pain threshold (P=0.506). The overall percentages of explained variance were lower in the tolerance interval model (20.2%) than in pain tolerance (23.1%) and threshold (33.1%), suggesting the increasing share of other confounding variables in pain tolerance and even more so in tolerance interval model. ----- CONCLUSIONS: These results suggest a significant association between experimentally induced pain tolerance and tolerance interval with material status, suggesting that poor people indeed do hurt more