A porous metal coating applied to a solid substrate implant has been shown, in vivo, to offer advantages over current polymethylmethacrylate cement fixation in orthopedic devices. These advantages may be lost, however, in devices requiring a sintering heat treatment to apply the coating since these treatments may have a detrimental effect on the substrate material mechanical properties. In addition, more biocompatible interface coating materials have come of interest with recent literature reports of metal ion release. These coatings may be of particular use in porous-coated systems since the surface area of implant in contact with the surrounding tissues is greatly increased. This study investigated the effects that both a porous Ti- 6Al -4V alloy coating and a ULTI carbon coating have on the fatigue properties of a Ti- 6Al -4V alloy substrate system. The fatigue properties of uncoated as-received, uncoated sinter heat treated and notched Ti- 6Al -4V material were also investigated. The results of this study revealed endurance limits for Ti- 6Al -4V alloy tested with a rotating beam system of 617 MN/m2 (uncoated as-received), 624 MN/m2 ( ULTI carbon-coated), 377 MN/m2 ( sinter heat treated), 220 MN/m2 (notched) and 138 MN/m2 (porous-coated). No effects on fatigue properties were observed when testing the material in saline compared with air. The slight increase in fatigue strength for the carbon-coated material is thought to be due to the increase in surface hardness resulting from the formation of titanium carbides on the surface. The low-endurance limit of the porous-coated material is due to both the transition from the as-received equiaxed microstructure to a lamellar microstructure upon sintering and to the notch effect created by the porous coating.

Alloys↗

PubMedDate not supplied

A histologic and mechanical evaluation of carbon-coated polyester suture.

Ultra low temperature isotropic (ULTI) carbon-coated polyester suture material was evaluated histologically and mechanically in dogs. These results were compared to those obtained for uncoated polyester and polybutylate coated polyester. The suture materials were used in the repair of the surgically incised medial collateral ligament and subcutaneous tissues to evaluate the potential of the carbon-coated system for ligamentous repairs. Following surgery, the dogs were sacrificed at periods of 1-48 weeks postoperatively for evaluation of tissue biocompatibility and mechanical strength of the materials. The polybutylate-coated polyester suture broke at lower force levels than did comparable sizes of uncoated or carbon-coated polyester. All three types showed a high retention (greater than 98%) of mechanical strength at 48 weeks, often exhibiting an increase in tensile strength due to tissue ingrowth. The histologic response to carbon-coated polyester was equal to or better than the response to either the uncoated polyester or polybutylate-coated polyester. A greater degree of tissue growth into the carbon-coated material was evident at most time periods following an initial acute inflammatory response which was also present in the other materials.

Animals↗

PubMedDate not supplied

IRAP--a system for the retrieval and analysis of orthopaedic implant data.

An interactive computer system for the storage, retrieval and analysis of standardized clinical and material characterization data associated with orthopaedic implants is described. The system consists basically of four independent modules. The essence of the system centers on the cross-referencing capabilities which are virtually unlimited. The system has been designed for use by non-computer trained personnel.

Humans↗

PubMedDate not supplied

A system for computer analysis of panorex radiographs.

Quantitative analysis of radiographs can be a very difficult and time-consuming task. Compounding this problem is a lack of standardization of films in a sequence of radiographs. Differences in magnification from film to film makes comparisons of parameters measured directly from the films virtually impossible. The system described in this paper allows for rapid comparison of non-standardized radiographs. In particular this system allows rapid measurements of alveolar ridge heights at 10 points on each side of a patient's face. Provisions allow for both mandibular and maximally studies, for reporting of means and standard deviations for each interval in a series, as well as for comparisons between intervals in a clinical sequence. Finally, graphic display allowing super-imposition of separate radiographs is possible, giving visual realization of clinically important changes in a patient's status.

Alveolar Ridge Augmentation↗

PubMedDate not supplied

Herpes simplex virus: molecular biology and the possibility of corneal latency.

Herpes simplex virus (HSV) is known to be latent in ganglionic neurons. Over the past eight years, a series of reports have described the isolation of HSV after organ culture of human corneas that had been removed in the course of penetrating keratoplasty. None of the corneas showed any clinical signs of active herpetic disease immediately before keratoplasty. Studies in rabbits and mice confirmed that HSV can be recovered from corneas by organ culture long after primary infection has subsided. Recently, sophisticated techniques of molecular biology, such as specific DNA or RNA probes, have been used to detect HSV nucleic acids in the cornea. The crux of the matter is whether the virus recovered from or detected in the cornea is 1) truly latent in cell populations that are nonneuronal; 2) resident in the cornea, replicating at a slow rate; or 3) newly arrived in the cornea following ganglionic reactivation. The evidence suggests that a guarded case can be made for limited HSV latency within corneal cells. HSV corneal latency would allow for reactivation, replication, and the immune response to occur in the absence of ganglionic HSV reactivation. Such a localized phenomenon has not, however, been demonstrated to occur clinically.

Animals↗

PubMedDate not supplied

Acanthamoeba keratitis.

Acanthamoeba species are an important cause of microbial keratitis that may cause severe ocular inflammation and visual loss. The first cases were recognized in 1973, but the disease remained very rare until the 1980s, when an increase in incidence mainly associated with contact lens wear was reported. There is an increased risk when contact lens rinsing and soaking solutions are prepared with nonsterile water and salt tablets. The clinical picture is often characterized by severe pain with an early superficial keratitis that is often treated as herpes simplex infection. Subsequently a characteristic radial perineural infiltration may be seen, and ring infiltration is common. Limbitis and scleritis are frequent. Laboratory diagnosis is primarily by culture of epithelial samples inoculated onto agar plates spread with bacteria. Direct microscopy of samples using stains for the cyst wall or immunostaining may also be employed. A variety of topically applied therapeutic agents are thought to be effective, including propamidine isethionate, clotrimazole, polyhexamethylene biguanide, and chlorhexidine. Various combinations of these and other agents have been employed, often resulting in medical cure, especially if treatment is commenced early in the course of the disease. Penetrating keratoplasty is preferably avoided in inflamed eyes, but may be necessary in severe cases to preserve the globe or, when the infection has resolved, to restore corneal clarity for optical reasons.

Acanthamoeba↗

PubMedDate not supplied

Gadoteridol in multiple sclerosis patients. A comparison of single and triple dose with immediate vs. delayed imaging.

Enhancement of lesions in multiple sclerosis (MS) has been investigated using standard and high doses of gadolinium. The purposes of this study are to compare the relative merits of single and triple dose as well as examine the merits of delayed triple-dose images in a large group of patients. Thirty-seven patients with multiple sclerosis underwent contrast enhanced brain magnetic resonance imaging (MRI). After noncontrast images, a single dose (0.1 mmol/kg) of gadoteridol was administered. Subsequently, axial T1-weighted images were obtained immediately after administration, and again after a delay of approximately 20 minutes. After an additional 0.2-mmol/kg dose was administered, to provide a total cumulative dose of 0.3 mmol/kg of gadoteridol, immediate and delayed axial T1-weighted image sequences were repeated. The contrast-noise ratio (C/N) was calculated for each identified, enhancing lesion in each series. Furthermore, blinded readings were performed to determine the lesion detection rate. Of the forty definite lesions that underwent all four sequences, triple-dose delayed images exhibited the highest contrast-noise ratio in a significantly larger number of lesions (p < 0.0001). Triple-dose immediate and delayed scans resulted in significantly higher contrast-noise ratios (6.47 and 9.99, respectively) when compared with those of the single dose scans (3.4 for immediate scans and 5.24 for delayed) (p < 0.01). The lesion detection rate was highest for triple dose delayed (95%), followed by triple-dose immediate (83%), single-dose delayed (68%) and finally, single-dose immediate scans (43%). Triple-dose immediate was noted to have a significantly increased (p < 0.0002) lesion detection rate with respect to the standard-dose immediate scans and standard-dose delayed scans (p < 0.02). In four lesions (10% of the total number of lesions), detection occurred only with the triple-dose delayed image sequence. Triple-dose 0.3 mmol/kg gadolinium with delayed imaging resulted in the highest lesion conspicuity and the highest lesion identification rate. There was a trend of progressively increasing detection rates from single-dose immediate scans to triple-dose delayed scans. Triple-dose delayed scans resulted in significantly higher (p < 2 x 10(-8) contrast noise ratios than all other sequences of this study.

Brain↗