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 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This pilot study tested whether a semipermeable expanded polytetrafluoroethylene (e-PTFE) membrane could be used to induce new bone to cover the partially exposed surface of titanium and hydroxylapatite (HA)-coated endosseous implants. Twenty threaded titanium and 10 HA-coated implants were placed in the tibia of five mongrel dogs. The implants were placed in a manner that left the cervical 2 to 3 mm exposed. Fifteen implants were used as controls and the rest were covered with an e-PTFE membrane. Animals were killed at 6, 8, and 12 weeks. Those implants covered by the membrane showed a progressive formation of bone on the exposed portion. The threaded titanium control implants showed reactive periosteal bone formation in the adjacent area, but no new bone formation on the exposed threads. The HA-coated controls, however, showed progressive bone formation on the exposed portion. Membrane position appeared to have an effect on the quantity of bone that formed, as those test sites in which there was a collapse of the membrane against the implant showed less new bone than those in which a protected space was created. This study showed that guided tissue generation may be used to induce new bone to form over the exposed portion of an implant, that the amount of new bone is influenced by the width of the space between membrane and implant, and that new bone forms on an exposed HA-coated implant even in the absence of a guiding membrane.
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PMID:Bone formation over partially exposed implants using guided tissue generation. 132 16

Titanium dioxide (TiO2) dust has generally been regarded as a "nuisance dust" in experimental animals and men. In this experiment, 16 dogs were exposed intratracheally to TiO2 dust for 9-15 months. The scanning electron microscopy with energy dispersive analysis of X-ray (SEM-EDAX), performed to identify the elemental composition of dust particles used in the study and in the focal lesions of the lungs, showed that dust particles were nearly pure titanium. Dust in the lung deposited mainly in the respiratory bronchioles and adjacent alveoli, with many alveoli filled by compacted dust particles. The pulmonary responses consisted of slight alveolitis, centrilobular emphysema, focal collapse of alveoli, and fibroblast hyperplasia with a few collagen fibres surrounding some of the TiO2-dust foci. Electron microscopically, many alveolar macrophages with intact nuclei contained a great amount of dust particles in their lysosomes, and in the dust foci, most of type I pneumocytes disappeared and type I pneumocytes showed hyperplasia. The alveolar subepithelial basement membrane were markedly thickened and bundles of collagen fibres were formed in the interstice. These findings suggest that TiO2 dust is one of the sorts which probably induce mild lung fibrosis in case a large amount is deposited in the lung tissue.
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PMID:[Pathogenic effects of titanium dioxide dust on the lung of dogs--a histopathological and ultrastructural study]. 279 52

The use of an expandable intramedullary device for internal fixation of metacarpal or phalangeal bones is described. The device is applicable to transverse fractures, short oblique fractures, or transverse osteotomies. The device consists of a cylindrical apparatus made of titanium that allows collapse in the circumferential diameter. It is introduced into the medullary canal in its collapsed state, and on release expands to its normal diameter in the canal with the fracture reduced over it. A biomechanical evaluation compared the stability of this device with other commonly employed fixation methods. A retrospective review is presented of the first 43 patients in whom the device was implanted.
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PMID:Biomechanical and clinical evaluation of the expandable intramedullary fixation device. 335 Dec 17

Because the hand tolerates disuse so poorly, the beginning of early motion following fractures is important in achieving early restoration of function. This report concerns the use of a unique, expandable intramedullary device for internal fixation of metacarpal or phalangeal shaft fractures that renders enough intrinsic stability that motion may be started early without fear of loss of reduction. The device is applicable for transverse or short oblique fractures and consists of a cylindrical apparatus made of titanium that allows for collapse in the circumferential diameter. It is introduced into the medullary canal in its collapsed state, and then is released to allow reexpansion into its normal diameter in the canal with the fracture reduced over it. This gives excellent fixation and affords stability approaching that of normal bone. Minimal postoperative immobilization is needed and early restoration of motion is possible. The device may also be used to immobilize metacarpal bones or phalanges following osteotomies, and it appears to be excellent for fixation of the bone in digits to be replanted. No complications have occurred in the reported series.
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PMID:Expandable intramedullary device for treatment of fractures in the hand. 379 65

To develop a new prosthesis for treating tracheal stenosis and tracheobronchomalacia, we examined the usefulness of an intratracheal stent made of shape memory alloy (SMA), a titanium-nickel alloy composed of 50% of each metal. At its recovery temperature (37 degrees C), the SMA stent was designed to recall the memorized shape of a coil with a diameter of 5 or 6 mm and a length of 10 mm. For the present experiment, it was transformed to a smaller coil 3 mm in diameter at a low temperature (-50 degrees C) and then loaded into the prosthesis introducer tube. An experimental model of potentially fatal tracheomalacia was made surgically by cutting and fracturing the tracheal cartilages of rabbits and tracheal collapse was confirmed by rigid bronchoscope. The introducer tube with the SMA stent was inserted and then the prosthesis was advanced into the collapsed segment of the trachea using the stent pusher. The SMA stent warmed bo body temperature and recovered its memorized shape after 1-2 min. In 3 out of 8 rabbits, follow-up bronchoscopy performed at 6, 8, and 10 months after implantation revealed satisfactory patency of the SMA stent and the trachea. After follow-up, 3 animals were sacrificed for histological observation, which showed little proliferation of granulation tissue and no dislocation of the SMA stent from the malacic portion. The remaining 5 rabbits have been followed for 18-24 months and are doing well. We conclude that the SMA stent maintains good tracheal patency, causes little reaction in the tracheal wall, and is easy to handle. Thus, it shows the potential for clinical application.
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PMID:[Experimental study of an intratracheal stent made of shape memory alloy]. 783 16

A mixture of demineralized freeze-dried human cortical bone and resorbable tricalcium phosphate was used in conjunction with an expanded polytetrafluoroethylene membrane to promote deposition of bone for ridge augmentation. A titanium screw was used to prevent collapse of the regenerative materials. A clinical report is presented in which an atrophic ridge was reconstructed buccolingually, permitting the placement of a root form implant in a previously untenable site.
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PMID:Ridge augmentation utilizing guided tissue regeneration, titanium screws, freeze-dried bone, and tricalcium phosphate: clinical report. 792 Mar 87

The reasons for unsuccessful decannulation after a laryngotracheoplasty may be multifactorial depending on the techniques used. Excessive granulation tissue may develop, necessitating further adjunctive procedures. Cartilaginous grafts may get infected, resorb, or collapse into the tracheal lumen. Bulky regional skin-muscle flaps may dehisce under tension or collapse into the tracheal lumen. Medial migration of the split ends of the anterior cartilaginous tracheal rings ensues with subsequent restenosis. Donor-site morbidity may compound these problems as well. During a 2.5-year period, we have performed laryngotracheoplasty on nine patients with 60% to 100% tracheal stenosis using titanium reconstruction plates. The split anterior tracheal wall is fixed by the plates in its expanded position. A neurovascularized strap-muscle flap is used to reconstruct the anterior tracheal wall. The flap becomes epithelialized with squamous epithelium within 3 weeks. Successful decannulation was possible in seven of the nine (78%) patients with no further respiratory problems. Of these, six required no further procedures. This technique offers a viable simple alternative to other methods of laryngotracheoplasty without the need for donor cartilage grafts or thick bulky skin-muscle flaps.
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PMID:Tracheoplasty using titanium reconstructive plates with strap-muscle flap. 808 27

A technique is described for augmenting an edentulous ridge buccally with a mixture of freeze-dried bone and resorbable tricalcium phosphate covered with a Gore-Tex membrane. Titanium screws are used to prevent the collapse of the regenerative materials. In the patient described, the buccolingual dimensions of the edentulous mandibular ridge more than doubled, thus allowing the placement of two implant cylinders. The rationale for such a procedure is discussed.
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PMID:Ridge augmentation with titanium screws and guided tissue regeneration: technique and report of a case. 822 70

A kinematic analysis of the movement of the scaphoid, the lunatum and the triquetrum has shown that their turning axes do not correspond with each other. Without arthritis, and within the range of normal motion, the bones move without imposing any appreciable load on the ligaments. They merely guide the bones and hold them together. In the case of arthritic disorders and in states where abnormal frictional resistance occurs, or following trauma, the ligaments are highly loaded. This could lead to increased wear and ruptured ligaments. A series of 20 arthroscopies has shown that LT and SC ligaments are very prone to this, and are often affected simultaneously. Therefore, there may be certain predisposed sites or "weak points", which should definitely not be further aggravated by inappropriate therapeutic measures. The clinician can classify the carpal dysfunction into five main groups; however, the therapy options cannot be classified in the same way. On the basis of clinical experience and the kinematic study, the following statements can be made: scapho-lunatum (SC) arthrodesis can be considered kinematically unsuitable, while scapho-capitatum (SC) and lunato-capitatum (LC) arthrodeses are both clinically and kinematically acceptable. LC arthrodesis has given good results in cases with advanced carpal collapse. From a mechanical point of view, SC arthrodesis is probably better than scapho-trapezo-trapezoid arthrodesis. In the case of ulnar translocation, radio-ulna-to-scaphoid arthrodesis could be an acceptable alternative to total fusion. Proximal row carpectomy can only be a temporary solution, as can prostheses. Partial prostheses, whether of Silastic or titanium, are also not suitable for permanent use.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Arthrosis of the wrist joint due to carpal instability. Therapeutic alternatives]. 845 Oct 52

We have carried out a prospective study of 17 patients (14 women, 3 men) of mean age 48 years (21 to 76) with transcervical fractures of the femur using MRI to detect early evidence of avascular necrosis of the head. Two fractures were Garden stage I, 12 stage II, and three stage III. We performed internal fixation under radiological control at a mean of five days (2 to 15) after injury using a titanium cannulated cancellous screw or a titanium compression hip screw. MRI was performed at one, six and 12 months and then yearly after operation. T1- and T2-weighted images were obtained by a spin-echo technique. The duration of follow-up of patients who did not subsequently require replacement of the head of the femur was from 2 to 5 years (mean 3.2). One month after operation eight of the 17 hips showed a band of low signal intensity on T1-weighted images and high signal intensity on T2-weighted images indicating lesions in the femoral head away from the fracture line. These were of three types: type I was a small infarct at the superolateral region of the femoral head and was seen in three hips; type II was a shallow lesion from the superolateral region to the fovea of the femoral head (three hips); and type III was a large lesion occupying most of the femoral head (two hips). No further changes were seen in the MRI after six months from operation. Collapse of the femoral head did not occur in the three hips with type-I lesions, but two of the three type-II hips and both type-III hips subsequently collapsed. At the final follow-up the three hips with a type-I lesion and one with a type-II were still asymptomatic but radiography showed sclerosis in the femoral head corresponding to the MRI lesions. The nine hips which showed no changes on MRI at one month had no abnormal findings on physical examination, radiography or MRI at final follow-up.
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PMID:MRI of early osteonecrosis of the femoral head after transcervical fracture. 866 37


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