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The benefits provided by rapid prototyping (RP) of patient anomalies in complex surgeries of the pediatric spine and pelvis were elucidated and characterized.Surgeons involved in the study were solicited from the Texas Scottish Rite Hospital for Children and the network of Shriners Hospitals for Children throughout the United States. Rapid prototyping models were created at Boise State University through a federally funded Economic Development Agency grant (Economic Development Agency Project Number 07-79-05312). Rapid prototyping models and detailed survey forms were supplied to lead surgeons for 13 cases of multiplane spinal or pelvic deformity.Results indicated that surgeons found RP models useful for preoperative planning, reference during surgery, communication with patients, and for increasing the safety of the procedure. Rapid prototyping models also led to a reduction in operating time in 4 of the 5 surgeries to correct congenital scoliosis/kyphosis.Surgeons can expect properly constructed RP models to provide significant benefits for complex surgeries of the pediatric spine and pelvis in the areas of preoperative planning, intrasurgical navigation, and communication with patients. A reduction in operating time may also be expected for cases of congenital scoliosis/kyphosis.This study was a type II prospective observational study of physicians' perceptions of the use of RP models to assist with surgical cases. Results provided by this study suggest expected benefits from application of RP in surgeries of the pediatric spine and pelvis with complex deformities.

Non-invasive impact analysis can be used to detect loosened bolts in a steel structure composed of construction-grade I beams. An electronically enhanced stethoscope was used to acquire signals from a moderate to light impact of a hammer on a horizontal steel I beam. Signals were recorded by placing the diaphragm of the stethoscope on the flange of either the horizontal beam or the vertical column proximal to a bolted connection connecting the two members. Data were taken using a simple open-loop method; the input signal was not recorded, nor was it used to reference the output signal. The bolted connection had eight bolts arranged in a standard configuration. Using the “turn of the nut” standard outlined by the Research Council on Structural Connections (RCSC, TDS-012 2-18-08), the bolted joint was tested in three conditions: turn of the nut tight, finger tight, and loose. We acquired time-based data from each of 52 patterns of the eight bolts in three conditions of tightness. Results of both time and frequency-based analyses show that open-loop responses associated with detorqued bolts vary in both amplitude decay and frequency content. We conclude that a basic mechanism can be developed to assess the structural health of bolted joints. Results from this project will provide a framework for further research, including the analysis of welded joints using the same approach.

The authors develop 3-D models of the pediatric knee from magnetic resonance imaging (MRI) image files, with the goal of minimizing injury to the pediatric growth plate during surgery. Computerized tomography (CT) scans have better resolution and contrast between bone and soft tissue than MRI scans; however, surgeons rely upon MRI scans to plan knee-joint surgeries such as anterior cruciate ligament (ACL) reconstruction. Surgeons can use the virtual models to plan and verify surgical procedures such as hole drilling and ligament attachments, and to determine volume removed from a growth plate due to different drill-hole placements with various drill sizes.

A method for detecting loosened bolts in a structural joint based upon open-loop acoustic measurement is presented. The acoustic measurement is taken direclty on the bolt head. The response of the bolt to a proximal hammer impact is evaluated and characterised using wavelet decomposition of the signal measured from the bolt head. Results are presented from a set of structural bolts in several conditions of preload and looseness. The study could enable a quick and simple method for detecting and evaluating detorqued bolts in structural joints.

Valgus slipped capital femoral epiphysis is a rare entity; approximately, 26 cases in 31 hips have been reported in the orthopedic literature since 1926. It has been argued that epiphyseal displacement occurs only in a posterior or posteromedial direction, and that the radiographic appearance of true valgus or lateral slippage is an optical illusion owing to the rotation of the femur. We present the cases of two sisters with bilateral lateral slipped capital femoral epiphysis without a posterior component of displacement. In these cases, the radiographs suggested that the direction of displacement was in the lateral plane and was confirmed with computerized tomography and three-dimensional reconstructions. Analysis demonstrated the absence of posterior slippage of the proximal femoral epiphysis. The slippage was treated with percutaneous screw placement. In cases in which the direction of the slip may be in question, advanced imaging techniques may be useful for precise determination of the screw placement. This may assist in the preoperative planning, and reduce the risk of inappropriate screw placement J Pediatr Orthop B 16:201–203 c 2007 Lippincott Williams & Wilkins.

Auscultatory percussion (AP) is an examination used to detect brain disease. The physical mechanisms involved in AP are investigated by determining the natural frequencies and mode shapes of an elastic, fluid-filled spherical shell containing a concentrically located elastic sphere. The major assumptions are that the fluid is inviscid, the spherical shell is thin, and the modes of the physical system are axisymmetric. An analytical modal analysis results in a characteristic equation for the natural frequencies of the physical system. Roots of the characteristic equation were found numerically. The results show that the spectra of natural frequencies for the physical system are distorted by the combined effects of the elasticity of the inner sphere and the reduction of fluid volume due to the inner sphere. The elastic inner sphere also introduces a pattern of additional frequencies to the spectra of natural frequencies of the physical system.

Objective To assess a new technique for the detection of free pleural fluid. Design 118 consecutive inpatients with radiologic evidence of free pleural fluid and a control group of 175 randomly selected inpatients were examined over a three-year period in a prospective blind study by auscultatory percussion (AP) for evidence of pleural effusion. The cutoff in the percussion note by AP is strikingly loud and sharp at the fluid level and allows precise delineation of even minimal amounts of pleural fluid. The fluid level was measured in reference to the last rib. The criterion for detection of pleural effusion by AP was a demonstrable horizontal fluid level at the sound cutoff across the posterior hemithorax above the last rib that shifted with lateral tilt. Setting A general medical and surgical university-affiliated teaching Veterans Affairs hospital. Patients/participants All inpatients were eligible. Ready availability of examiners was essential. Rotating third- and fourth-year medical students, residents, and senior staff members participated. Interventions None. Major results 113 of the 118 patients with radiologic evidence of pleural effusion had a distinct horizontal fluid level above the last rib that shifted with lateral tilt (sensitivity = 95.8%). None of the 175 control patients examined at random showed evidence of pleural effusion by AP examination, which was confirmed by chest radiography (specificity = 100%). Nine of the 175 patients without radiologic evidence of pleural effusion had elevated diaphragms that simulated a fluid level in the examination by AP. Each of the nine patients, however, had no shift in the level with lateral tilt. Subpulmonic effusions were readily displaced and identified by this method of AP. Conclusions Examination by AP is highly sensitive and specific for the detection of free pleural fluid, even in the presence of obesity, thickened pleura, lung masses, pneumonia, and associated lung disease. The examination correlates closely with standard and lateral decubitus chest radiography. Pleural effusion unsuspected by conventional means of physical examination and undetectable by standard chest radiography can readily be detected by the method of AP. The examination is easy to do and is particularly suited to enhance detection of pleural effusion. As little as 50 mL of free pleural fluid can be detected.

The subject matter of this presentation will refer to the preliminary development of a non‐destructive and non‐invasive diagnostic method using low‐frequency acoustic emissions to characterize and diagnose joint and muscle disorders. Low‐frequency acoustic emissions have had limited effectiveness when used in the past to characterize and diagnose joint and muscle disorders because Fourier transform techniques were not capable of describing when a specific frequency occurred during an acoustic emission event. With the development of techniques that decompose a signal into time‐frequency representations using wavelet analysis it is now possible to describe complex transient signals. While the continuous wavelet transform (CWT) method has already made an impact within many areas of the medical sciences such as EEG analysis, ECG analysis, and DNA‐sequence analysis, the method is now becoming popular for analyzing muscle and joint acoustic emissions from the hip, knee, and elbow joints. This paper will present...