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Non-contacting laser ultrasound is used to measure Young’s modulus, shear modulus, and Poisson’s ratio as functions of temperature for Alloys 617 and 709. These alloys are of interest for structural applications in advanced nuclear reactors. Design rules for the construction of elevated-temperature nuclear components are presented in Section III, Division 5 of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. The ASME B&PV Code for each material provides Young’s modulus values tabulated as a function of temperature and a single, temperature-independent Poisson’s ratio value. Elastic properties characterized by laser ultrasonics for Alloy 617 are in good agreement with data collected using an American Society for Testing and Materials (ASTM) standard resonant frequency technique and values reported from literature, demonstrating its accuracy. The shear modulus and Poisson’s ratio as functions of temperature for Alloy 709 have not been reported previously. Laser ultrasonics is well suited for determining temperature-dependent elastic properties, and the method offers the ability to perform measurements on small irregularly shaped specimens.

Proper femoral interference screw placement during endoscopic anterior cruciate ligament reconstruction is technically demanding. Potential graft injury and the high incidence of screw divergence can be decreased by using the tibial tunnel for screw advancement, as described in this article.

Magnetic resonance (MR) evaluation was performed on patients with titanium spine implants. The objective was to determine the value of conventional MR for evaluating the postoperative spine with titanium implants. The value of MR imaging for evaluation of the postoperative spine without metal implants is well known. The results of MR evaluation of the titanium instrumented spine have not been explored. Thirty patients with titanium spine implants underwent MR evaluation. Indications included pain, neurologic deficit, decompression evaluation, and infection. The titanium implants caused only local MR signal void and did not interfere with the imaging of the adjacent soft tissues. This provided significant information and helped determine whether further surgical intervention was required. There is significant value of MR evaluation of the post-operative spine without compromise from titanium implants.

The upper extremities of two elderly cadavers were amputated at the fore-quarter level and underwent placement of the Biomet uniflex humeral nail in the left extremities and the Richards Russell-Taylor humeral nail in the right extremities. Distal locking screws were placed lateral to medial in the Biomet nails and in the anterior to posterior plane in the Richards nails. Dissection was performed about the distal humerus to identify the neurovascular structures at risk from screw placement. The radial nerve was at direct risk with lateral to medial screw placement and the ulnar nerve and median nerve/brachial artery bundle was at risk if significant overpenetration of the medial cortex occurred. The musculocutaneous nerve was at direct risk with placement of a distal screw from anterior to posterior. Sections of the distal humerus demonstrated the medullary canal to begin narrowing at 3 cm and fill with dense bone 1.5 cm superior to the proximal edge of the olecranon fossa. This may interfere with distal placement of the humeral nail, altering the position of the distal fixation holes, and also may contribute to distraction at the fracture site.

A retrospective review of 36 patients treated with posterior cervical plating and autogenous iliac crest bone graft was performed to evaluate the results of posterior cervical plating in terms of fusion, outcome, technique, and complications. Numerous methods of cervical stabilization have been described with varying fusion rates and complications. Compared to wiring techniques, there is little information concerning the results of posterior cervical plating. Thirty-six patients with cervical instability underwent posterior plating with lateral mass screw fixation. Twenty-two had acute traumatic instability, four had late traumatic instability, six had metastatic disease, and four had postlaminectomy spondylotic instability. A Minerva brace was worn postoperatively for 3 months and fusion was assessed by bone incorporation on plain films, stable dynamic flexion-extension views, and absence of neck pain. Postoperative MRI and CT imaging was assessed in those patients who underwent these modalities. Fusion occurred at an average of 3 months in all patients. One patient demonstrated postoperative neurologic deterioration, but this resolved with subsequent decompression. Six patients had loosening of short, unicortical screws, but this did not affect the fusion result in five of these patients. The use of titanium implants allowed operative CT and MR imaging without the excessive artifact associated with stainless steel implants. Posterior cervical plating with lateral mass fixation and bone grafting offers a reliable method of achieving fusion. Bicortical lateral mass screws are less likely to loosen than unicortical screws, and no major complications occurred.

Several types of pedicular screw systems have been utilized to augment lumbar spine fusion. All systems are made of stainless steel, which interferes with imaging techniques, especially MRI and CT scans. In search of a solution for this problem, we decided to study the use of titanium systems in the lumbar spine. Because there were no titanium pedicle screw systems available on the market, we decided to use the titanium Alta system currently used for femur fractures. This report details our experience in using this device for lumbar spine fusion. From 1990 to 1992, 25 patients underwent thoracic and lumbar fusion with Alta titanium screws and plates. Spinal fusion was performed for a variety of conditions, including metastatic tumor, fracture, spondylolisthesis, pseudoarthrosis, and postdecompressive instability. All but two patients obtained solid fusion clinically and radiographically and considerable improvement in back pain. There was loosening of the implant in both patients. Both patients had osteoporosis. One of these two patients developed pseudoarthrosis, which required further surgery. The other patient with a metastatic tumor of the spine remained asymptomatic without change in the spine alignment despite progression of the tumor. There were no broken screws encountered during follow-up. Two patients sustained subsequent fracture of the vertebra above the fusion. One of the patients also developed a fracture below the fusion. Fusion with titanium implants allowed postoperative evaluation and subsequent periodic examination of the spinal canal with high-quality MR images as well as significant reduction of artifacts on CT scan.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomic and radiographic studies were performed on three cadaveric pelves to define recommendations for better anterior pelvic external fixator pin placement. A thick zone of bone was identified for pin purchase beginning along the iliac crest 2-3 cm posterior to the anterior superior iliac spine (ASIS), and extending 6-8 cm posteriorly along the crest. This zone is hourglass-shaped, and follows the superior gluteal ridge to the superior acetabular region. This zone has a maximal thickness of 4 cm in the supra-acetabular region, and a minimum of 8 mm at the isthmus. Cortical pin penetration is more likely to occur if pin placement begins in the lateral third of the iliac crest, or if the pin is advanced beyond the isthmus of this zone, 5 cm from the crest. Acetabular penetration occurs when the pins are advanced farther than 10.5 cm. Radiographic evaluation demonstrates that only the pelvic outlet view gives the proper orientation of the iliac tables to guide the angle of the pin placement (24 degrees from vertical) and to confirm proper pin placement. Computed tomography (CT) evaluation with "inlet" positioning of the gantry gives complementary information for pin placement.

The United States government provides health care for one of the largest beneficiary populations in the world. Approximately 796,500 (35%) of the 2.27 million dependent children of uniformed services personnel are adolescents (13 to 19 years old). Although the majority of dependent children are dependents of active duty personnel (74.7%), close to half of the adolescents (47.7%) are dependents of retired personnel. Recent geopolitical world changes and a perceived decreased threat to national security have led to a planned 25% reduction of the active duty force by 1996. The mean age of children beneficiaries will rise as a result. Pediatricians in the military and civilian contract physicians need to prepare for increased health care of older pediatric patients, particularly adolescents.

The refusal of blood products by Jehovah's Witnesses creates ethical and medicolegal dilemmas for the treating physician. Appropriate management involves some understanding of the beliefs of the Jehovah's Witnesses and knowledge of a variety of techniques to minimize blood loss. This case report describes the treatment of a Jehovah's Witness with severe anemia and multiple skeletal injuries. The need to keep blood loss to a minimum influenced the management of this patient.