Suggestions for the uses of psychological devices in accord with legal and ethical standards.

Suggests that some traditional psychological practices no longer conform to current legal and ethical requirements and that several ethical standards in the official publications of the American Psychological Association are applicable to the use of psychological devices. In the treatment of problems with possible organic causes, collaborative relationships with physicians may be required. The Food and Drug Administration's recent classification of some psychological devices (e.g., biofeedback equipment) as medical devices is likely to impose new standards upon the distribution and use of psychological devices similar to those now required for medical devices. Failure to conform to these standards may be considered as evidence of negligent treatment under some state laws. Finally, these standards suggest that public statements and announcements about devices should be based upon scientifically acceptable evidence and that psychologists should not participate for personal gain in the commercial promotion of a proprietary or single-source device to the public. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How safe are silicone breast implants?

The Food and Drug Administration's recent decision to limit the use of silicone gel breast implants was surrounded by a great deal of misleading information in the popular press. This article outlines the most relevant information available in the literature on the most often raised safety issues, including the carcinogenicity of silicone, speculation on a possible connection between silicone and autoimmune disease, the significance of gel bleed, and the effect of implants on mammography. In this attempt to better educate primary care physicians, we explain what is known about silicone gel breast implants so physicians can more wisely counsel their patients, who may be needlessly frightened by inaccuracies they have heard.     

Regulatory hurdles in bringing an in vitro diagnostic device to market

We discuss the hurdles that developers and manufacturers of in vitro diagnostic devices face in obtaining regulatory approval to market their products in the US. A thorough understanding of medical device regulation and the early planning of a clinical and regulatory strategy are imperative in assuring successful and timely launches of new products. Finally, it is critical for manufacturers to establish a working partnership with the Food and Drug Administration to expedite their new product applications.     

Use of cervicothoracic junction pedicle screws for reconstruction of complex cervical spine pathology

STUDY DESIGN: A retrospective review of 21 patients in which cervical pedicle screw fixation was used at C7 with or without upper thoracic pedicle screw fixation. OBJECTIVE: To evaluate the use of pedicle screw placement in the lower cervical spine. SUMMARY OF BACKGROUND DATA: The use of posterior cervical spine fixation, including lateral mass fixation, has become increasingly popular in recent years. However, lateral mass fixation at C7 is often hindered by lack of substantial high quality bone. The end level of long cervical spine constructs is frequently C7 or T1. Dissatisfaction with lateral mass fixation at C7 and T1 led the authors to use lower cervical pedicle screw fixation for several cervical spine disorders. METHODS: Twenty-one patients who had undergone cervical pedicle screw fixation at C7 were reviewed retrospectively. There were 12 males and 9 females, with an average age of 52 years. All pedicle screws were placed, after direct palpation of the pedicle, with a right angle nerve hook after laminoforaminotomy at C7. RESULTS: There were no neurologic complications related to pedicle screw placement, and no patient was symptomatically worse after the operation. Six patients with root pathology improved. Of 14 patients with cervical myelopathy, 12 improved at least one Nurick grade, and 2 had no improvement. There were no failures of fixation or complications related to pedicle fixation at a minimum of 1 year follow-up. CONCLUSION: Pedicle screws in C7 placed with laminoforaminotomy and palpation technique appears to be safe and efficacious. Excellent fixation can be achieved.     

Chronicle of a defective heart valve prosthesis

The Bj?rk-Shiley convexo-concave (BScc) strut fracture problem is about to enter its third decade. At present, valve carriers still face the risk of outlet strut fracture; a risk which does not seem to decline. The temporising attitude of the manufacturer has led to far more victims than would have been necessary but also the Food and Drug Administration, regulatory agencies outside the US and the medical community share responsibility for this problem.     

Transcutaneous or transconjunctival peribulbar anesthesia?

The complications of 648 consecutively inserted Universal AO pedicle screws (140 in the thoracic spine and 508 in the lumbar spine) performed by one surgical team to treat 91 patients with spinal problems, were reviewed. The spinal pathology consisted of: scoliosis (34 patients), degenerative lower lumbar spinal disease (25 patients), neoplastic spinal disease (11 patients), thoracic kyphosis (8 patients), spinal fractures (7 patients), lumbo-sacral spondylolisthesis (3 patients), and osteomyelitis (3 patients). Intraoperative complications were: screw misplacement (n = 3), nerve root impingement (n = 1), cerebrospinal fluid leak (n = 2) and pedicle fracture (n = 2). Postoperative complications were; deep wound infection (n = 4), screw loosening (n = 2) and rod-screw disconnection (n = 1). The conclusion was that pedicle screw fixation has an acceptable complication rate and neurological injury during this procedure is unlikely.     

Promoting emergency contraception

The use of available oral contraceptive agents for emergency contraception has been judged safe and effective by the U. S. Food and Drug Administration and other agencies. Yet implementation by physicians has been limited, and only a small percentage of women take advantage of this option each year. Lack of a specially packaged--and marketed--product for this indication has been a major barrier.     

Oral fluconazole for vaginal candidiasis

The recent surge of interest in fluconazole is due to its approval by the U.S. Food and Drug Administration for use as a single 150-mg oral dose in the treatment of vaginal candidiasis. Fluconazole is a triazole antifungal agent that acts primarily by inhibiting sterol synthesis in the fungal cell membrane. Recent studies have shown that a single dose of oral fluconazole is as effective as intravaginal antifungal agents. Many physicians and patients prefer this single-dose regimen because of its low rate of side effects, cost-effectiveness and ease of administration.     

A protocol to evaluate semi-rigid pedicle screw systems

The objective of the current study was to develop an in vitro testing protocol to evaluate semi-rigid pedicle screw devices. A corpectomy model protocol exists to evaluate rigid spinal implants; however, semi-rigid devices are contraindicated for this condition. This paper describes a technique that simulates more closely the conditions a semi-rigid device would see in vivo. Finally, the new testing protocol is used to evaluate the DDS pedicle screw-cable system. Benefits and shortcomings of the new protocol are discussed.     

Overall false positive rates in tests for linear trend in tumor incidence in animal carcinogenicity studies of new drugs

Based on results of simulation and empirical studies conducted within the Divisions of Biometrics, Center for Drug Evaluation and Research, Food and Drug Administration, and in collaboration with the National Toxicology Program, the Center has recently changed the significance levels for testing positive linear trend in incidence rate for common and rare tumors, respectively, from 0.01 and 0.05 to 0.005 and 0.025. The overall false positive rate resulting from the use of this new rule in the tests for linear trend in a two-species-two-sex study is about 10%, the rate that is judged as the most appropriate in a regulatory setting by the Center. This paper describes two of the studies.     

In vitro simulation. Early results of stereotaxy for pedicle screw placement

STUDY DESIGN: Frameless stereotaxy with doppler ultrasound and three dimensional computer model registration is assessed in vitro for pedicle screw placement. OBJECTIVE: To identify feasibility of pedicle screw navigation and placement using this technology. SUMMARY OF BACKGROUND DATA: Inaccurate pedicle screw placement can lead to neurovascular injury or suboptimal fixation. Present techniques in pedicle screw placement involve only confirmation of hole orientation. METHOD: Forty-four pedicle screws were placed in lumbosacral models and cadaver specimens. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning. RESULTS: All screws were intrapedicular. Accuracy of anterior cortical fixation was 1.5 mm, with a range of 2.5 mm. CONCLUSION: In vitro frameless stereotaxy is accurate for pedicle screw placement. This technology adds a component of navigation to pedicle screw placement.     

Anterior transpedicular fixation of the lower thoracic and lumbar spine. Experimental verification using a new direction finder

Currently, no anterior spinal implant provides a strong bone-screw interface because of the cancellous characteristics of the vertebral body. A more secure anchorage could be obtained by anterior transpedicular screw fixation. Four hundred transpedicular screws located between T7 and L5 were placed using the newly developed direction finder. Measurements were obtained directly from radiographs of the cadaveric specimens. In 10 cases (2.5%), the screws crossed the medial pedicle border, but never by more than 1.4 mm. A lateral protrusion was noted in another 41 screws (10%), with no protrusion greater than 2.2 mm. Encroachments beyond the superior or inferior border were not observed. The mean angle of the screws at each level measured between 7 and 19 in the transverse plane and between 2 and 4.5 in the sagittal plane. This technique should be reserved for vertebrae without significant arthritic changes. The rare screw with minimal infraction through the medial or lateral pedicle wall should not cause any vascular or neural compromise. The anterior transpedicular screw technique appeared relatively safe (88%) and encouraged the development of the new plate system for anterior spinal stabilization.     

Fatal cardiac tamponade associated with posterior spinal instrumentation. A case report

STUDY DESIGN: Case report of a fatal complication of pedicle screw instrumentation and review of the literature. OBJECTIVE: To describe the clinical and postmortem findings in a 35-year-old man who sustained a T11 burst fracture that was managed by transpedicular posterior instrumentation and who died 12 days after surgery of cardiac tamponade caused by a prick injury of the right coronary artery. SUMMARY OF BACKGROUND DATA: Posterior pedicle screw instrumentation is considered a safe and effective method for stabilizing a spinal motion segment. Nevertheless, there are several rare but significant complications that may occur. This is the first report of a heart tamponade after transpedicular screw insertion. METHODS: A 35-year-old man was treated for a T11 burst fracture with posterior transpedicular stabilization. The surgery was uncomplicated. RESULTS: Twelve days after the intervention, the patient died of cardiogenic shock. Postmortem examination showed a heart tamponade of 350 mL blood originating in a prick injury of the right coronary artery. Histologic findings showed evidence that the injury was caused during surgery by a Kirschner wire. CONCLUSION: There are numerous possible intraoperative complications in posterior pedicle screw fixation, such as nerve root and spinal cord injuries. This case of a fatal heart tamponade after transpedicular screw insertion is rare. It shows that the surgeon must be aware of potential risks associated with such a procedure and have a comprehensive three-dimensional understanding of the anatomic structures involved.     

In case of emergency: no need for consent

The Food and Drug Administration (FDA) is amending its current informed consent regulations to permit harmonization of the Department of Health and Human Services' (DHHS) policies on emergency research and to reduce confusion on when such research can proceed without obtaining an individual subject's informed consent. This regulation provides a narrow exception to the requirement for obtaining and documenting informed consent from each human subject, or his or her legally authorized representative, prior to initiation of an experimental intervention. The exception would apply to a limited class of research activities involving human subjects who are in need of emergency medical intervention but who cannot give informed consent because of their life-threatening medical condition, and who do not have a legally authorized person to represent them. FDA is taking this action in response to growing concerns that current rules are making high quality acute care research activities difficult or impossible to carry out at a time when the need for such research is increasingly recognized.     

Restoration of pedicle screw fixation with an in situ setting calcium phosphate cement

STUDY DESIGN: Pedicle screws were pulled out of human cadaveric vertebrae before and after augmentation with polymethylmethacrylate or in situ-setting calcium phosphate cement. The fixation strength of screws augmented with calcium phosphate cement was compared with that of screws augmented with polymethylmethacrylate. OBJECTIVES: To determine whether a new in situ-setting calcium phosphate cement might be suitable for augmenting the fixation of pedicle screws. The principle objective was to compare the pull-out resistance of screws augmented with calcium phosphate cement with the pull-out behavior of screws augmented with polymethylmethacrylate. Polymethylmethacrylate augmentation was chosen as the standard because of its current clinical use. Five types of screws were tested to determine whether screw design had an effect on the efficacy of augmentation. SUMMARY OF BACKGROUND DATA: Although many factors affect the pull-out resistance of pedicle screws, a key determinant of their performance is the strength of their attachment to the spine. In elderly, osteopenic patients, the screw-bone interface is especially at risk for stripping during insertion or pull-out after surgery. In these patients, polymethylmethacrylate has been used to augment pedicle screw fixation, although its use is not without risk. In situ-setting calcium phosphate cements may provide an alternative to polymethylmethacrylate in this application. Like polymethylmethacrylate, calcium phosphate cements can be injected into the prepared screw hole. They have the added advantage of being resorbed and replaced during healing and normal bone remodeling. METHODS: Thirty human lower lumbar vertebrae (L3-L5) were implanted bilaterally with one of five types of pedicle screws (n = 6 for each screw type). The screws were pulled out 3.0 mm at 0.25 mm/sec with a servohydraulic materials testing machine. The 3.0-mm pull-out distance, which was slightly longer than one thread pitch, was designed to strip the screw-bone interface but to leave the pedicle otherwise intact. After the initial testing, the screws in each vertebrae were removed, and the screw tracks were filled with 2.0 cc of polymethylmethacrylate (one side) or calcium phosphate cement (contralateral side). After augmentation, the screws were reinserted, and the cements were allowed to harden for 24 hours. Postaugmentation testing followed the protocols for preaugmentation testing, and the pull-out resistance of screws augmented with calcium phosphate cement was compared with the pull-out resistance of screws augmented with polymethylmethacrylate. RESULTS: Mechanically, calcium phosphate cement compared favorably with polymethylmethacrylate for augmenting pedicle screws. Both restored the strength of the screw-bone interface: across all screw types, the average increase in pull-out strength was 147% with polymethylmethacrylate augmentation and 102% with calcium phosphate cement. There were no significant differences because of screw type with either type of augmentation. CONCLUSIONS: The in situ-setting calcium phosphate cement investigated in this study compared favorably with polymethylmethacrylate in a single-cycle, pull-out test of augmented pedicle screws in senile trabecular bone. With further evaluation, this cement may offer an alternative to polymethylmethacrylate for the enhancement of pedicle screw fixation clinically.     

Medication development and testing in children and adolescents. Current problems, future directions

Progress in pediatric psychopharmacological research has suffered notable delay, especially compared with the achievements in adult psychopharmacology. Although safety and efficacy of the use of many psychotropic agents in children remain largely unproved, their pediatric use has been increasing and their widespread off-label prescribing by practitioners has raised some important concerns. The National Institute of Mental Health, in cooperation with the Food and Drug Administration and leading researchers, has coordinated systematic efforts to identify the major obstacles to research in pediatric psychopharmacology and to propose feasible solutions. In 1995, a conference cosponsored by the national Institute of Mental Health and the Food and Drug Administration gathered more than 100 research experts, family and patient advocates, and representatives of mental health professional associations. Participants met in working groups focused on specific aspects of child research and reached consensus on various recommendations. Each of the various aspects relevant to conducting research in this area (methodological, ethical, legal, regulatory, financial, and family or community context) presents specific challenges, which are herein outlined. Recommendations for possible solutions are presented, some of which are being implemented. Because data about drug safety and efficacy in adults can rarely be extrapolated to children, there is no substitute for pediatric psychopharmacological research. Successful strategies for overcoming the many obstacles with which this research has to contend must enlist the concerted efforts of all the relevant parties (investigators, clinicians, industry, federal agencies, ethicists, families, and community representatives).     

Instrumentation and techniques in equine fracture fixation

In recent years fracture fixation in the horse has changed significantly. New devices, mainly adapted from the human field, have been successfully introduced into large animal surgery. Examples of such implants include the DCS/DHS implant system, the self-tapping screw, the cannulated screw, and the pinless external fixator. However, new devices have also been developed exclusively for equine fracture management, including the interlocking intramedullary nail and the external skeletal fixation device. With these devices the surgeon has more options for repairing fractures in horses. Nevertheless, many problems are still unsolved. Indications exist that during the next few years new, exciting fracture fixation systems will be developed, providing further advancements in the quest for the ideal implant for horses. However, the development stages of these devices are such that mentioning the possibilities here is premature.     

Revision pedicle screws. Bigger, longer shims--what is best?

STUDY DESIGN: To evaluate the effect of change in screw dimensions and hole augmentation in pedicle screw revisions, the insertional torque was determined, and results were compared with those in control specimens in an in vitro study using cadaveric thoracolumbar spines. OBJECTIVES: To determine the best method of salvage for failed pedicle screws, by evaluating the insertional torque after placing a larger diameter or longer screw into a stripped hole. Use of a shim and use of larger and longer screws were also investigated. Finally, the effect on insertional torque of simply removing and replacing a pedicle screw in its original hole was investigated. SUMMARY OF BACKGROUND DATA: The effects of using bigger or longer screws and shims to salvage failed pedicles have been studied. The interaction between how much larger, how much longer, and inserting with or without shims, has not been well studied. Optimizing reinsertional torque through the use of bigger screws risks exceeding the pedicle capacity. Using longer screws risks violation of the anterior vertebral body, thereby placing the great vessels and viscera at risk. By knowing the relative contribution of increase in length and diameter, the surgeon can optimize the risk-benefit ratio. METHODS: Eight cadaveric spines from T10 to S1 were harvested. The specimens underwent radiographic screening and bone densitometry. A modified Latin square randomization was designed to evaluate the screw diameters and lengths. Each pedicle was its own control. A 35- x 6.5-mm screw was used as a control. Test screws were placed after pedicle screw hole failure was achieved and documented by stripping. For the test screws, the diameters were increased by 1 mm and 2 mm, the lengths were increased by 5 mm and 10 mm. Shims were added randomly. The peak insertional torque was measured for each control screw and test screw placement. In addition, during each screw placement, the screw was removed and replaced to determine the effect. RESULTS: Insertional torque, after the pedicle screw is removed and replaced in the same hole, was decreased by 34% (P < 0.000005). Increasing the diameter of the salvage screw by 2 mm caused the insertional torque to be increased by 8.4% of the original. Increasing the length of the screw did not improve the salvage screw insertional torque. There was an interaction effect for the 1-mm increase in diameter and the increase in length. At this diameter, increasing the length had a significant effect (P = 0.009) on the salvage torque. Using a shim created no improvement in salvage insertional torque (P = 0.77). There was a poor linear correlation between torque and bone mineral density (r = 0.18) in these osteoporotic specimens. CONCLUSIONS: Removing and replacing a pedicle screw in its original hole substantially decreases its mechanical fixation. For pedicle salvage, increasing the diameter causes the greatest restoration of strength. Shims had no effect in pedicle salvage in osteoporotic specimens.     

Controversy over the silicone gel breast implant: current status and clinical implications

The silicone gel breast implant controversy has generated much confusion, making informed decision making for physicians and patients increasingly difficult. In order to better understand the controversy, we review the steps taken by the Food and Drug Administration and the resultant status of breast implants. The currently available scientific data are summarized with regard to cancer development and detection, implant rupture and gel migration, and autoimmune disorders. By reviewing the presently available information on silicone gel breast implants, we can better address the concerns of our patients.     

Complications of pediatric thoracolumbar and lumbar pedicle screws

STUDY DESIGN: This was a retrospective review of 223 consecutive cases (1986-1996) from one institution where 759 thoracolumbar and lumbar pedicle screws were used in the treatment of various pediatric spinal disorders in patients less than 18 years of age. OBJECTIVES: To determine the incidence of short- and long-term (> 2 years follow-up) complications in this group of patients-specifically, complications related to instrumentation and those directly attributable to pedicle screws in these pediatric patients. SUMMARY OF BACKGROUND DATA: Although much has been written regarding the use of pedicle screws in the adult population, no published study has examined complication rates with regard to thoracolumbar and lumbar pedicle screws placed for pediatric spinal disorders. METHODS: A retrospective review of 223 consecutive cases involving 759 pedicle screws placed for a variety of pediatric spinal disorders was performed. Complications were divided into short term and long term (> 2 years follow-up) and into those relating to instrumentation and those relating to pedicle screws specifically. RESULTS: Short-term complication occurred in 5 patients (2.2%) for a total of 17 screws ultimately removed. Only two of these patients had screws removed for lumbar radicular complaints. No residual sequellae resulted. No long-term (> 2 years postoperative) complications were noted. CONCLUSION: Low short- and long-term complication rates specific for pediatric pedicle screws suggests that for properly trained spinal surgeons, pedicle screws fixation in the pediatric population can be performed safely to treat a variety of spinal disorders.