Influence of a functional dynamic loading on bone ingrowth into surface pores of orthopedic implants.
Explore the source record for details and available documents.
Aged↗
SEARCH · Search PubMed
Results for “Bone Nails”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Histologic evaluation of the osseous adaptation to titanium and hydroxyapatite-coated titanium implants.
The aim of this study was to obtain more information about the bone reaction to titanium and hydroxyapatite (HA)-coated titanium implants during the first 3 months after implantation. Therefore, uncoated and coated implants were inserted into the tibia of rabbits for various implantation periods. The histological results demonstrated that although there were no marked differences in bony reaction at the cortical level to the different implant materials, HA-coating appeared to induce more bone formation in the medullary cavity. It was also noted, that 3 months after insertion loss of coating thickness had occurred.
Animals↗
Evaluation of poly(DTH carbonate), a tyrosine-derived degradable polymer, for orthopedic applications.
The polymerization of desaminotyrosinetyrosylhexyl ester (DTH) with phosgene gives rise to poly(DTH carbonate), a new pseudopoly(amino acid). To evaluate the performance of this bioabsorbable material in orthopedic applications, the tissue responses elicited by compression-molded pins of poly(DTH carbonate) and clinically used polydioxanone pins (PDS; Orthosorb) were compared. The two types of pins were implanted in the paravertebral muscle and in the metaphyseal proximal tibia and distal femur of 10 White New Zealand Rabbits for 1, 2, 4, and 26 weeks. The tissue response was evaluated using histologic staining of soft- and hard-tissue sections, fluorescent bone marker of incorporation, and backscattered electron imaging. In soft tissue, both poly(DTH carbonate) and PDS elicited a mild inflammatory response resulting in encapsulation. During the disintegration phase, the PDS implants triggered a foreign body response involving the phagocytosis of polymeric debris by histiocytes and giant cells. No such response was observed for poly(DTH carbonate). In hard tissue, close bone apposition was observed throughout the 26-week test period for poly(DTH carbonate) implants. At the 26-week time point, the poly(DTH carbonate) implants exhibited surface erosion and were penetrated by new bone. In contrast, an intervening fibrous tissue layer was always present between the PDS pins and the bone. At 26 weeks, the PDS implants had partially resorbed and a foreign body response characterized by infiltration in several of the implantation sites. This study indicates that poly(DTH carbonate) and PDS exhibit fundamentally different interactions with hard tissue, and that poly(DTH carbonate) is a promising orthopedic implant material.
Absorption↗
Development of a variable stiffness external fixation system for stabilization of segmental defects of the tibia.
The mechanical properties of a variable stiffness external fixation system were explored. Initial testing of a unilateral fixator configuration demonstrated that system rigidity could be increased by maximizing pin separation distance in the fracture component and the number of pins used while minimizing pin separation distance across the fracture site and the sidebar offset distance from bone. A triangulated system composed of half pin frames mounted anteriorly and medially on the tibial aspects and linked by crossbars was devised. Progressive disassembly of the frame was shown to result in progressive decreases in fixator rigidity in all planes.
Biomechanical Phenomena↗
Guidelines for external fixation frame rigidity and stresses.
Using results from FEM analyses and experiments as references, analytical methods are applied to develop simple approximate formulas to relate frame rigidity, maximal pin stresses, and peak pin-bone stresses in external fracture fixation (EFF) configurations in axial loading to the most important frame, pin, and bone parameters. It is found that, in a realistic range, the parameters can be adapted to vary the frame rigidity from about 13 N/mm to 17,000 N/mm, thereby reducing the maximal stresses in the pins and at the pin-bone interface by a factor of 140. In particular, when compromises have to be established in the frame characteristics in order to ensure a flexible configuration and limit the stress values at the same time, the formulas presented can provide useful guidelines. The side-bar separation and the pin modulus, in particular, can be adapted to decrease the rigidity, while only moderately increasing the stresses, thereby reducing changes for pin failure, pin-bone loosening, and pin-tract infection. A nomogram is presented for a quick reference to estimated relations between frame characteristics, rigidity, and stresses. It is believed that this material may be of use in EFF design and applications in clinical and animal experimental trials.
Biomechanical Phenomena↗
Torsion and bending analysis of internal fixation techniques for femoral neck fractures: the role of implant design and bone density.
To evaluate pin/screw/plate fixation for management of femoral neck fractures, 39 proximal femora were tested in both torsion and flexion under physiological loading conditions. Three, four, or five implants of six commonly used multiple-fixation devices, and a sliding hip screw with and without an additional 6.5-mm cancellous screw were examined in paired femora. The intact and postfixation femora were initially subjected to a single applied moment, and the torsion and bending stiffness were determined from the load-deformation data. Postfixation femora were also subjected to cyclic loading in flexion at three load ranges, and fixation was judged successful if no failure occurred on or before 1,500 cycles of 667 to 2,000 N of a combined compressive force and moment. Anterior-posterior and lateral radiographs of each specimen were taken after fixation in order to evaluate Singh's index of bone density, fracture reduction, implant placement, and cross-sectional diameter of the femoral neck. Bone density was also evaluated by computed tomography (CT) and physical measurement of core samples obtained from the femoral head. The results indicate that there appears to be no justification for the use of more than three pin/screw implants for management of femoral neck fractures. Bone density was found to correlate with fracture stability and may be a useful predictor of fixation success.
Aged↗
Pin tract infections: a canine model.
The purpose of this study was to examine three issues: the relationship between the length of time of skeletal pin insertion and bacterial infection, the connection between skin organisms and the intramedullary infecting agent, and the length of time necessary for the medullary canal to sterilize itself after pin removal. Skeletal pins were inserted in a group of dogs, and a direct correlation was found between the duration of time that the pins remained in the bone and positive intramedullary cultures. The infecting agent in 88% of the medullary cultures was also cultured from the skin. In a second group of dogs, the pins remained in place for 1, 2, 3, or 4 weeks, respectively. The pins were removed, and the pin tracts were permitted to heal for varying periods of time. The medullary canals were then cultured. No medullary canal was infected when the pin tracts were allowed to heal for greater than or equal to 3 weeks. Therefore, if pin tracts are allowed to heal for at least 3 weeks prior to performance of osteosynthesis, the chances of deep infection are probably lessened.
Animals↗
Restoration of tissue components after insertion of absorbable fracture fixation devices of polyglycolide through the articular surface: an experimental study in the distal rabbit femur.
Absorbable implants for fracture fixation do not require a secondary removal procedure, a fact that could make them particularly suitable for intra-articular fixation, provided the degree of regeneration of the articular surface is acceptable. To determine the restoration pattern in distal rabbit femurs after the intra-articular insertion of absorbable fixation devices, polyglycolide pins and screws were implanted through the articular surface of the intercondylar portion of the bone in adult animals. The polymer was known to have a degradation time of approximately 20 weeks. At follow-up times of 3-48 weeks, the restoration of the tissue components was examined histomorphometrically and microradiographically. The intact contralateral femur served as an internal control. The first signs of degradation of the implants were seen at 6 weeks. The mean fractional osteoid formation surface of the bone trabeculae within the sample fields showed significantly increased values until 6 weeks but thereafter approached the level of the control femur. In the 36-week and 48-week specimens, the polyglycolide had been absorbed and the intra-articular entrance of the implant channel had become filled either with firm whitish tissue resembling mature articular cartilage or with soft undifferentiated mesenchymal tissue only. Good restoration of the trabecular bone architecture corresponding to the original subchondral bone was a prerequisite for the regeneration of the articular cartilage. The causes of the dichotomous pattern of restoration could not be identified, but possibly it represented a normal biologic variation.(ABSTRACT TRUNCATED AT 250 WORDS)
Absorption↗
Effect of bone cylinder length on distraction osteogenesis in the rabbit tibia.
The viability and osteogenic potential of bone cylinders for bone transport was investigated in one tibia of 18 mature male New Zealand rabbits. The length of the bone cylinder was equal to or twice that of the diameter of the tibia. The cylinder was cut subperiosteally with an externally cooled oscillating saw from a lateral approach, after a specific unilateral external fixator had been applied. To simulate bone transport, one end of the cylinder was fixed to the distal bone stump by a cerclage wire and healing and revascularization was prevented by an interposed expanded polytetrafluoroethylene membrane. The periosteum was re-adapted and sutured, and distraction began 10 days postoperatively at 0.25 mm/12 hours for 22 days. New bone formation in the distraction gap was quantified by dual energy x-ray absorptiometry and by computer-assisted histomorphometry of polyfluorochrome-labeled undecalcified bone sections and corresponding microradiographs. In half of the animals with each size cylinder, osseous bridging occurred, so the findings on distraction osteogenesis are reported only for the remaining nine animals. Generally, centripetal mineralization of the gap with two distinct zones of ripening bone structures and a central radiolucent fibrocartilaginous zone could be distinguished. Neither absorptiometry nor histomorphometry showed significant differences in the overall amount of this new bone formation for the bone cylinders of two different lengths. However, osteogenesis was significantly greater at the proximal end than at the cylinder. New bone was formed predominantly from endosteal sites in the smaller cylinders and from periosteal sites in the larger cylinders. Histologically, there was complete necrosis of both sizes of cylinders, followed by revitalization through newly formed vascular channels.(ABSTRACT TRUNCATED AT 250 WORDS)
Absorptiometry, Photon↗
Porous ceramics as bone graft substitutes in long bone defects: a biomechanical, histological, and radiographic analysis.
Three porous ceramic bone graft materials were compared with regard to their ability to heal a 2.5 cm defect created surgically in a bilateral canine radius model. The ceramic materials were analyzed at 12 and 24 weeks after surgery and included tricalcium phosphate, hydroxyapatite, and collagen hydroxyapatite, which contained a mixture of 35% tricalcium phosphate and 65% hydroxyapatite with added collagen. Each material was evaluated alone and with added bone marrow aspirate. All the implants were compared with a graft of autogenous cancellous bone in the contralateral radius. Biomechanical testing and radiographic evaluation revealed that the addition of bone marrow aspirate was essential for tricalcium phosphate and hydroxyapatite to achieve results comparable with those of cancellous bone. Collagen hydroxyapatite performed well without the addition of bone marrow, although the addition of marrow did have a positive effect. Further qualitative radiographic and histological analysis demonstrated that tricalcium phosphate was the only ceramic that showed any sign of degradation at 24 weeks. This observed degradation proved to be an important factor in evaluating radiographs because the radiodensity of collagen hydroxyapatite and hydroxyapatite interfered with the determination of radiographic union. At 24 weeks, tricalcium phosphate with bone marrow was the material that performed most like cancellous bone. In this study, the biomechanical and radiographic parameters of tricalcium phosphate with bone marrow were roughly comparable with those of cancellous bone at 12 and 24 weeks. Tricalcium phosphate was the only implant that showed significant evidence of degradation at 24 weeks by both histological and radiographic evaluations, and this degradation took place only after a degree of mechanical competence necessary for weight-bearing was achieved.
Animals↗
Fibrous dysplasia of bone: management and outcome of 20 cases.
BACKGROUND AND OBJECTIVES: Fibrous dysplasia of bone is difficult to manage because of its variable clinical course with many different methods of treatment reported. Therefore we report on our experience. METHODS: We reviewed a series of 20 patients with 32 lesions included. The average age at the time of diagnosis was 32 years for monostotic disease, 26 years for polyostotic disease, and 3 years for McCune-Albright syndrome. The median follow-up period was 6 years. Functional and radiographic outcomes were scored. RESULTS AND CONCLUSIONS: Monostotic disease mostly presented with a circumscribed lesion and monitoring was often sufficient. Symptomatic circumscribed lesions showed satisfactory outcome when treated with curettage, cryosurgery and bone grafting. Lesions of the extended type were most of all seen in polyostotic disease and eventually needed operative treatment. In case of bony deformity, corrective osteotomies and rigid internal fixation were performed in addition to curettage, cryosurgery, and bone grafting. In polyostotic disease, expected outcomes were good, but in McCune-Albright syndrome, results were uniformly poor. J. Surg. Oncol. 2001;76:157-166.
Adolescent↗
A histomorphometric observation of flows in cortical bone under dynamic loading.
Ferritin was used as a histological marker for interstitial fluid flows in four goats. Two transcortical pins were inserted into each tibia mediolaterally-one at the proximal side and one at the distal side of the diaphysis. For the experimental limb, dynamic loading was applied to the pins on the lateral side. The contralateral limb was used as control. Ferritin was injected into the nutrient arteries feeding the two tibiae. The goat was then euthanized immediately. Undecalcified slides of the tibial cortical bone from both the experimental and the control limbs were studied histologically. Percentages of Haversian systems marked with ferritin halos and the average radial distance of ferritin transudation away from the Haversian canals were assessed. Results for the medial and lateral sides of both the experimental and control tibiae were reported. Significant differences in the ferritin transudation distance were found between the experimental and the control tibia (P < 0.005) and between the medial and the lateral sectors (P < 0.05). The approach documented in this paper could be used to address systematically how external loading might affect the transport phenomena in cortical bone.
Animals↗
[Effect of early mobilization following Kapandji's method of intrafocal wiring in fractures of the distal end of the radius. Results of a prospective study of 60 cases].
We have undertaken a prospective study of the management of fractures of the distal radius using three Kirschner wires as advocated by Kapandji. 30 were immobilised and the other 30 allowed early movement. Complications involving pin migration and rupture of extensor tendons occurred only in the latter group, and one patient in the other group developed Reflex Sympathetic Dystrophy. At three months there was no statistically significant difference in movement or level of pain between the two groups. Grip was better after two months in those mobilised early. The final radiographic appearances were similar in both groups. Early mobilisation should only be used in patients who have good quality bone and will carefully observe instructions after operation.
Adolescent↗
Avascular necrosis of the femoral head: a review of the indications and results of Sugioka's transtrochanteric rotational osteotomy.
The results of Sugioka's trans-trochanteric anterior rotational osteotomy are reported. Seventeen cases of idiopathic avascular necrosis of the femoral head have been operated upon and followed-up for between 10 to 48 months, with an average of 25.2 months. Since 1975 the operative technique and complications are described and the clinical results were assessed according to Patterson's criteria. These results are compared with previous methods of treatment. The short term results of Sugioka's method are favorable in cases with a small to medium sized necrosis. This new method of re-orientation of the head provides an intact part of the femoral head for weight bearing and therefore would seem to be appropriate in cases without established osteo-arthritis.
Adolescent↗
Simultaneous anterior and posterior approaches for correction of late deformity due to thoracolumbar fractures.
Thirty-one patients with an average age of 27 years were included in this study to analyze the short-term results of simultaneous anterior and posterior approaches in the treatment of late complications of thoracolumbar fractures. The complications treated were pseudoarthrosis and malunion resulting in neurologic compromise and pain. There were 20 burst fractures, 2 fracture/dislocations, and 9 compression fractures in this group. Average preoperative Sagittal Index was 35 degrees, which improved to an average of 4 degrees after surgical treatment. The average Motor Index Score improved from 90 to 98 after surgery. Average follow-up was 16 months. Average estimated blood loss was 2000 ml and average operation time was 5 h. It was concluded that the late problems associated with thoracolumbar fractures can be addressed quite adequately with simultaneous anterior and posterior approaches. The simultaneous anterior and posterior approach is associated with decreases in operating time, blood loss, and hospital stay. Technical advantages of the simultaneous technique include elimination of acute instability between the stages, protection against dislodgment of the graft, and application of the posterior instrumentation under complete visualization of the anterior graft.
Adult↗
Carbon as an implant material in orthopaedic surgery.
Carbon is a material of proven value in many fields of medicine. It has only minor reactions compared with other materials, but does have unfavourable mechanical characteristics. New kinds of carbon with similar physical characteristics to other materials, e.g. steel and ceramic, have now been developed.
Animals↗
[Condensor field irradiation (27.12 mhz) and osteosynthetic implants (author's transl)].
The question whether metals implanted in tissue may induce heat damage is yet controversial. Due to physical laws an increased production of heat is to be expected around the metal parts directed towards the capacitor plates. This is due to a converging and shunting effect of the metal in the electric field. Model experiments show that the shunting effect is most significance for the production of heat damage close to the metal. No heat damage is to be expected under the four following conditions: 1. linear or 2-dimensional osteosynthesis implantats are in a rectangular position to the electric field, 2. the metal is covered with at least 10 mm of tissue, 3. the tissue between the capacitor plates is of a with at least 40 mm and 4. common used frequency generators or field intensities are applied. Reported results suggest to investigate whether the high frequent electrical field influences the fracture regeneration advantageously.
Animals↗
Stabilization of osteochondral fractures: an experimental study comparing polyglycollic acid degradable pin with K-wire stabilization in rabbits.
Conventional metal implants may be unsuitable for the stabilization of osteochondral fractures as they may interfere with joint function and eventually require implant removal. We therefore compared the use of biodegradable implants with conventional metal ones in an animal experimental study conducted in skeletally mature rabbits. Biodegradable polyglycollic acids pins (PGA) 1.5 mm in diameter were used to stabilize an osteochondral fragment surgically created in the distal femur of rabbits. In another group of 36 animals, conventional metal K-wire of the same diameter was used for stabilization. The animals were killed at intervals of 3 to 24 weeks. Satisfactory union of the fragments was noted in 92% of the PGA implants as compared with 50% with the metal implants group. No implant migration was seen in the PGA group, while migration was noted in all animals with the metal implants. Histological studies showed that in 80% of the cases fixed with PGA implants, the fragment was viable. In the metal group 33% of the fragments underwent fragmentation and necrosis.
Animals↗