Noise and thermal performance of a sub-attofarad capacitance sensor for precision measurements, with applications in gravitational wave detectors.

We describe the design principles, fabrication, and characterization of a precision AC resonant capacitance bridge (RCB) sensor, based on a resonant differential planar printed circuit board transformer with a solid (ungapped) MnZn ferrite core, demonstrating a short-term sensitivity at 293 K of 0.225 ± 0.005 aF/√Hz at around 120 kHz resonance frequency and 1 Hz Fourier measurement frequency. At 120 K, the RCB short term noise sensitivity is 0.118 ± 0.005 aF/√Hz. We compare the ungapped configuration to five different RCBs: three with a core gap of 65 µm and two with a core gap of 130 µm. Their average room temperature short term noise sensitivities are 0.30 ± 0.01 and 0.45 ± 0.01 aF/√Hz, while the cryogenic operation of these transformers at 120 K resulted in averaged sensitivities of 0.23 ± 0.01 and 0.36 ± 0.01 aF/√Hz, respectively. Multi-hour room temperature runs, with one core of each of the three gap types, proved the stability of their long-term sensitivities of 0.234 ± 0.005, 0.338 ± 0.009, and 0.435 ± 0.010 aF/√Hz for the ungapped (40-h duration) and the 65 and 130 µm (28-h duration) cores, respectively. At 0.1 mHz, a critical frequency for space gravitational wave detectors, the respective sensitivities are 0.25 ± 0.02, 0.35 ± 0.02, and 0.53 ± 0.07 aF/√Hz. Measurements with the ungapped transformer configuration for temperatures from 325 to 349 K further validate the dependence of the noise model on temperature and permeability. The performance of our RCB with an ungapped core matches the calculated performance value and shows an improvement in signal-to-noise ratio of two or more compared with capacitance bridges developed for similar applications. A further factor of about two noise reductions is achieved by cooling to 120 K.

Association between habitual snoring, middle ear disease, and speech problems in young children with non-syndromic cleft palate anomalies.

The purpose of this study was to investigate the association between habitual snoring (HS), middle ear disease (MED), and speech problems in children with cleft palate. This cross-sectional study included children aged 2.0-7.9 years with non-syndromic cleft palate anomalies. Parents completed the Pediatric Sleep Questionnaire and a questionnaire about MED. Audiograms and speech assessment were also conducted. Ninety-five children were enrolled; 15.2% of families reported HS, 97.6% MED, and 17.1% speech problems. HS (37.5% vs 10.3%, P = 0.007) and early episodes of MED (92.3% vs 58.2%, P = 0.021) were more likely to be reported for children with isolated cleft palate when compared to those with cleft lip and palate. Children with cleft lip and palate had a higher frequency of MED with effusion compared to those with Robin sequence (86.4% vs 57.1%, P = 0.049). The odds ratio for HS in children with ≥1 episode of MED in the last year was 7.37 (95% confidence interval 1.55-35.15, P = 0.012). There was a trend for children with speech problems reported by parents to have HS (30.8% vs 11.5%, P= 0.076). Anatomical factors play a role in the frequency of upper airway symptoms in children with cleft palate. A recent history of at least one episode of MED was associated with an increased frequency of HS.

Tissue engineering and regenerative approaches to improving the healing of large bone defects.

Despite the high innate regenerative capacity of bone, large osseous defects fail to heal and remain a clinical challenge. Healing such defects requires the formation of large amounts of bone in an environment often rendered hostile to osteogenesis by damage to the surrounding soft tissues and vasculature. In recent years, there have been intensive research efforts directed towards tissue engineering and regenerative approaches designed to overcome this multifaceted challenge. In this paper, we describe and critically evaluate the state-of-the-art approaches to address the various components of this intricate problem. The discussion includes (i) the properties of synthetic and natural scaffolds, their use in conjunction with cell and growth factor delivery, (ii) their vascularisation, (iii) the potential of gene therapies and (iv) the role of the mechanical environment. In particular, we present a critical analysis of where the field stands, and how it can move forward in a coordinated fashion.

Prophylactic amifostine prevents a pathologic vascular response in a murine model of expander-based breast reconstruction.

BACKGROUND: Although expander-based breast reconstruction is the most commonly used method of reconstruction worldwide, it continues to be plagued with complication rates as high as 60% when radiotherapy is implemented. We hypothesized that quantitative measures of radiotherapy-induced vascular injury can be mitigated by utilizing amifostine in a murine model of expander-based breast reconstruction. METHODS: 30 rats were divided into three groups: expander placement (Control), expander placement followed by radiotherapy (XRT), and expander placement followed by radiotherapy with amifostine (AMF/XRT). All groups underwent placement of a sub-latissimus tissue expander. After a 45 day recovery period, all groups underwent vascular perfusion and micro-CT analysis. RESULTS: Micro-CT analysis was used to calculate vessel volume fraction (VVF), vessel number (VN), and vessel separation (VSp). A significant increase in VN was seen in the XRT group as compared to the Control (p = 0.021) and the AMF/XRT (p = 0.027). There was no difference between Control and AMF/XRT (p = 0.862). VVF was significantly higher in XRT than either Control (p = 0.043) and AMF/XRT (p = 0.040), however no difference was seen between Control and AMF/XRT (p = 0.980). VSp of XRT was smaller when compared to both Control and AMF/XRT specimens (p = 0.05 and p = 0.048, respectively), and no difference was seen between Control and AMF/XRT (p = 0.339). CONCLUSIONS: Amifostine administered prior to radiotherapy preserved vascular metrics similar to those of non-radiated specimens. Elevated vascularity demonstrated within the XRT group was not seen in either the Control or AMF/XRT groups. These results indicate that amifostine protects soft tissue in our model from a radiotherapy-induced pathologic vascular response.

gLISA: geosynchronous laser interferometer space antenna concepts with off-the-shelf satellites.

We discuss two geosynchronous gravitational wave (GW) mission concepts, which we generically name gLISA. One relies on the science instrument hosting program onboard geostationary commercial satellites, while the other takes advantage of recent developments in the aerospace industry that result in dramatic satellite and launching vehicle cost reductions for a dedicated geosynchronous mission. To achieve the required level of disturbance free-fall onboard these large and heavy platforms, we propose a new drag-free system, which we have named "two-stage" drag-free. It incorporates the Modular Gravitational Reference Sensor (developed at Stanford University) and does not rely on the use of µN thrusters. Although both mission concepts are characterized by different technical and programmatic challenges, individually they could be flown and operated at a cost significantly lower than those of previously envisioned gravitational wave missions, and in the year 2015 we will perform at JPL a detailed selecting mission analysis.

Invited article: advanced drag-free concepts for future space-based interferometers: acceleration noise performance.

Future drag-free missions for space-based experiments in gravitational physics require a Gravitational Reference Sensor with extremely demanding sensing and disturbance reduction requirements. A configuration with two cubical sensors is the current baseline for the Laser Interferometer Space Antenna (LISA) and has reached a high level of maturity. Nevertheless, several promising concepts have been proposed with potential applications beyond LISA and are currently investigated at HEPL, Stanford, and EADS Astrium, Germany. The general motivation is to exploit the possibility of achieving improved disturbance reduction, and ultimately understand how low acceleration noise can be pushed with a realistic design for future mission. In this paper, we discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the "low-frequency" region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.

Validation of Histologic Bone Analysis Following Microfil Vessel Perfusion.

The ability to examine bone vascularity using Micro-Computed Tomography (µCT) following vessel perfusion with Microfil® and to subsequently perform histologic bone analysis in the same specimen would provide an efficient method by which the vascular and cellular environment of bone can be examined simultaneously. The purpose of this report is to determine if the administration of Microfil® precludes accurate histologic assessment of bone quality via osteocyte count and empty lacunae count. Sprague-Dawley rats (n=6) underwent perfusion with Microfil®. Left hemi-mandibles were harvested, decalcified and underwent vascular analysis via µCT prior to sectioning and staining with Gomori's Trichrome. Quantitative Histomorphometric evaluation was performed. Ninety-five percent confidence intervals were used to determine statistical differences from an established set of controls (n=12). Histologic analyses were successfully performed on specimens that had undergone previous perfusion. Quantitative measures of bone cellularity of perfused versus control specimens revealed no statistical difference in osteocyte count per high-power field (95.33 versus 94.66; 95 percent CI,-7.64 to 6.30) or empty lacunae per high-power field (2.73 versus 1.89, 95 percent CI, -1.81 to 0.13). Here we report a statistical validation allowing for histological analysis of cell counts in specimens in which Microfil® perfusion has previously been performed.

The effects of patch-potentials on the gravity probe B gyroscopes.

Gravity probe B (GP-B) was designed to measure the geodetic and frame dragging precessions of gyroscopes in the near field of the Earth using a drag-free satellite in a 642 km polar orbit. Four electrostatically suspended cryogenic gyroscopes were designed to measure the precession of the local inertial frame of reference with a disturbance drift of about 0.1 marc sec/yr-0.2 marc sec/yr. A number of unexpected gyro disturbance effects were observed during the mission: spin-speed and polhode damping, misalignment and roll-polhode resonance torques, forces acting on the gyroscopes, and anomalies in the measurement of the gyro potentials. We show that all these effects except possibly polhode damping can be accounted for by electrostatic patch potentials on both the gyro rotors and the gyro housing suspension and ground-plane electrodes. We express the rotor and housing patch potentials as expansions in spherical harmonics Y(l,m)(θ,φ). Our analysis demonstrates that these disturbance effects are approximated by a power spectrum for the coefficients of the spherical harmonics of the form V(0)(2)/l(r) with V(0) ≈ 100 mV and r ≈ 1.7.

Gravity Probe B: final results of a space experiment to test general relativity.

Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of general relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6601.8±18.3 mas/yr and a frame-dragging drift rate of -37.2±7.2 mas/yr, to be compared with the GR predictions of -6606.1 mas/yr and -39.2 mas/yr, respectively ("mas" is milliarcsecond; 1 mas=4.848×10(-9) rad).

A current 10-year retrospective survey of 199 surgically treated orbital floor fractures in a nonurban tertiary care center.

This study characterizes the surgically treated patient population suffering from orbital floor fractures by use of current data from a large series consisting of 199 cases taken from a nonurban setting. Data were gathered through a retrospective chart review of patients surgically treated for orbital floor fractures at the University of Michigan Health System, collected over a 10-year period. Data regarding patient demographics, signs and symptoms of presentation, cause of injury, nature of injury, associated facial fractures, ocular injury, and associated nonfacial skeleton trauma were collected. In total, there were 199 cases of orbital floor fractures among 189 patients. Male patients outnumbered female patients by a 2:1 ratio and were found to engage in a wider range of behaviors that resulted in orbital floor fractures. Motor vehicle accidents were the leading cause of orbital floor fractures, followed by physical assault and sports-related mechanisms. The ratio of impure to pure orbital floor fracture was 3:1. The most common signs and symptoms associated with orbital floor fractures, in descending order, were periorbital ecchymosis, diplopia, subconjunctival hemorrhage, and enophthalmos. Associated facial fractures were found in 77.2 percent of patients, the most prevalent of which was the zygoma-malar fracture. Serious ocular injury occurred in 19.6 percent of patients, with globe rupture being the most prevalent, accounting for 40.5 percent of those injuries. There was a 38.1 percent occurrence of associated nonfacial skeletal trauma; skull fracture and intracranial injury were the most prevalent manifestations. Associated cervical-spine fractures were rare (0.5 percent). Statistical examination, using odds ratios and chi-squared analysis, demonstrated significant associations that have not previously been reported. Impure and pure orbital floor fractures revealed striking differences in several demographic aspects, including mechanism of injury, signs and symptoms of presentation, spectrum of associated trauma, and the severity of concomitant trauma.

Maternal cigarette smoking during pregnancy and the risk of having a child with cleft lip/palate.

Maternal cigarette smoking during pregnancy as a risk factor for having a child with cleft lip/palate has been suggested by several epidemiologic studies. However, most of these studies contained small sample sizes, and a clear association between these two factors could not be established. The U.S. Natality database from 1996 and a case-control study design were used to investigate the association between maternal smoking during pregnancy and having a child with cleft lip/palate. The records of 3,891,494 live births from the 1996 U.S. Natality database were extracted to obtain cleft lip/palate cases and random controls. The National Center for Health Statistics collects maternal and newborn demographic and medical data from the birth certificates of all 50 states. New York (excluding New York City), California, Indiana, and South Dakota did not collect smoking data, and the data from these states were excluded from the analysis. A total of 2207 live births with cleft lip/palate cases were identified, and 4414 controls (1:2 ratio) were randomly selected (using the SAS program) from live births with no congenital defects. Odds ratios and 95 percent confidence intervals were determined from logistic regression models, adjusting for confounding variables, including maternal demographic and medical risk factors. A significant association was found between any amount of maternal cigarette use during pregnancy and having a child with cleft lip/palate [unadjusted odds ratio 1.55 (1.36, 1.76), p < 0.001]. Univariate analysis showed that maternal education level, age, race, and maternal medical conditions (diabetes and pregnancy-associated hypertension) were potential confounders. After adjusting for these confounders, the odds ratio remained significant [Mantel-Haenszel odds ratio 1.34 (1.16, 1.54), p < 0.001]. To determine the dose response of cigarette smoking during pregnancy, the cigarette consumption per day was divided into four groups: none, 1 to 10, 11 to 20, and 21 or more. A dose-response relationship was found when comparing each smoking category with the no smoking reference group: 1.50 (1.28, 1.76), 1.55 (1.23, 1.95), and 1.78 (1.22, 2.59), respectively. This means that increased cigarette smoking during pregnancy resulted in increased odds of having a child with cleft lip/palate. This is the largest study to date to test the association between maternal cigarette smoking during pregnancy and having a newborn with cleft lip/palate. The significant trend in the dose-response relationship strongly suggests the association of smoking tobacco and this common congenital deformity. These results emphasize the public health risks associated with smoking during pregnancy. To prevent this devastating craniofacial anomaly, educational initiatives should be considered that will alert expectant mothers to the association between smoking during pregnancy and the occurrence of cleft lip/palate.

A new technique for the quantitative analysis of cranial suture biology.

OBJECTIVE: Our objective was to assess the ability of the microcomputed tomography scanner to correctly image normal and synostosed cranial sutures at the ultrastructural level. DESIGN AND METHODS: Two specimens of coronal sutures were collected from operative specimens. After appropriate preparation, histological sections were obtained and stained with toluene blue for evaluation. Representative histological sections were compared to microcomputed tomography slices. RESULTS AND CONCLUSIONS: With microcomputed tomography, we successfully imaged one normal and one synostosed human coronal suture and performed a quantitative analysis of these specimens. Microcomputed tomography scanning was found to be a highly accurate imaging device for the evaluation of cranial suture development. Microcomputed tomography offers three-dimensional imaging at the microscopic level and allows for rapid quantitative analysis of bone architecture, including several measurements unavailable through histologic analysis. We believe that microcomputed tomography can play an important role in imaging and in the quantitative analysis of the stereology of bone microarchitecture. Among its advantages, microcomputed tomography is able to image many more slices than are obtainable through histology, and the method is not prone to human error. Microcomputed tomography slices are generated without destruction of the specimen and without loss or corruption of reproducible data. Structure-oriented slices from microcomputed tomography together with cellular-oriented sections from histology are complementary in the overall quantitative analysis of cranial sutures.

Facial bone grafts: Contemporary science and thought.

BACKGROUND AND OBJECTIVES: The use of bone grafts is a vital component of a surgeon's armamentarium in the reconstruction of congenital and acquired deformities of the craniofacial region. A thorough understanding of bone graft physiology and the factors thought to affect graft behavior is essential in order to develop a more intelligent use of the grafts in clinical applications. METHODS AND MATERIALS: This article presents a brief review of the basic physiology of bone grafts along with a survey of pertinent concepts and research currently available. Mechanical stress, rigid fixation, graft orientation, and the recipient sites are reviewed. RESULTS AND/OR CONCLUSION: In an attempt to bring together various issues that exist in current bone graft science, the authors propose new concepts. They suggest that the mechanical environment in which a bone graft is placed, revascularization of the graft, and the interaction between those two factors are the major predictors of clinical results.

A comparative analysis of the microarchitecture of cortical membranous and cortical endochondral onlay bone grafts in the craniofacial skeleton.

Previous work in this laboratory established that an onlay bone graft's survival is determined primarily by its relative cortical and cancellous composition rather than its embryologic origin. A volumetric analysis of external bone graft resorption, however, does not explain the internal microarchitectural changes that may be occurring as these grafts become incorporated. To expand the knowledge of bone graft dynamics beyond volumetric parameters, a better understanding of the internal processes of bone graft remodeling is needed. In this comparative study of cortical onlay bone graft microarchitecture, the authors propose to show that cortical onlay bone grafts undergo measurable internal microarchitectural changes as they become incorporated into the surrounding craniofacial skeleton. In addition, the authors propose to further demonstrate similarities between the internal microarchitecture of cortical onlay bone grafts of different embryologic origin over time. Twenty-five adult New Zealand White rabbits were used for this study. They were divided into two groups of eight animals and one group of nine. The groups were killed at 3, 8, and 16 weeks. Cortical membranous and endochondral bone grafts were placed subperiosteally onto each rabbit's cranium. In addition, five ungrafted cortical endochondral and membranous bone specimens were used as controls. Microcomputed tomography (MCT) scanning and histomorphometric analysis were performed on all of the specimens to obtain detailed information regarding the microarchitecture of the cortical bone grafts. The parameters of bone volume fraction, bone surface area to volume, mean trabecular number, and anisotropy were used to give quantitative information about a bone's micro-organization. The results showed that there is no statistically significant difference between the cortical endochondral and the cortical membranous bone grafts for bone volume fraction, bone surface to volume, mean trabecular number, and anisotropy measurements for all time points. There were, however, statistically significant differences when comparing the control and 3-week groups to the 16-week group for all parameters. The advanced MCT technology and histomorphometric techniques proved to be effective in providing a qualitative and quantitative ultrastructural comparison of cortical endochondral and membranous onlay bone grafts over time. In this study, a statistically significant change in the internal microarchitecture of cortical onlay bone grafts of different embryologic origins was seen as they were remodeled and resorbed at all time points. Specifically, the onlay cortical bone grafts developed a less dense, more trabecular, and less organized internal ultrastructure. In addition, no difference in the three-dimensional ultrastructure of cortical endochondral and membranous bone was found. These results challenge some of the currently accepted theories of bone-graft dynamics and may eventually lead to a change in the way clinicians approach bone-graft selection for craniofacial surgery.

The ultrastructure and resorptive pattern of cancellous onlay bone grafts in the craniofacial skeleton.

The authors' laboratory has shown cancellous onlay bone grafts to resorb faster than cortical grafts. To understand the nature of cancellous bone grafts beyond volumetric measurements, a temporal analysis of the internal microarchitecture of these grafts was performed. Their hypothesis is that the forces of remodeling and resorption cause cancellous onlay bone grafts to develop a denser, more interconnected, and a more mechanically stable microarchitecture. Twenty-five adult New Zealand White rabbits were used in this study and were divided into three groups. Microcomputed tomography (MCT) was performed on all cancellous bone grafts to obtain detailed information regarding the microarchitecture of the cancellous bone. Bone graft specimens were examined histologically, and histomorphometric analysis was also performed. Their results show that cancellous onlay bone grafts develop a higher bone volume fraction, mean trabecular thickness, connectivity, and degree of anisotropy. Furthermore, cancellous onlay bone grafts developed a lower bone surface area-to-volume ratio and mean trabecular separation. The unique combination of MCT technology and histomorphometric techniques proved to be effective in providing a qualitative and quantitative ultrastructural analysis of cancellous onlay bone grafts over time. The authors were able to show changes in the internal microarchitecture of cancellous onlay bone grafts as they were remodeled and resorbed. Specifically, they found the cancellous onlay bone grafts to develop a more dense, less trabecular, more organized, and more interconnected internal ultrastructure over time. Their findings have helped to provide a reproducible description of the temporal sequence of changes in bone microarchitecture, revascularization, and internal remodeling.

Investigation of the influences of biomechanical force on the ultrastructure of human sagittal craniosynostosis.

This study presents comparisons of the ultrastructure of synostotic and open portions of synostotic sagittal sutures using histomorphometry, scanning electron microscopy, and microcomputed tomography. By using stereologic and histomorphometric analysis, this study proposes to demonstrate evidence of the influence of biomechanical force on the suture during the process of sagittal craniosynostosis. Finally, we propose to link the pathologic changes transforming normal suture fusion to craniosynostosis with concurrent changes in the polarity of suture fusion initiation. Seven infants (four boys and three girls) with sagittal craniosynostosis, ranging in age from 1.4 to 4.8 months (mean = 3.0 months), underwent sagittal synostectomies. The synostotic bone specimens were sectioned into three regions: an open suture, partial synostosis, and complete synostosis. Microcomputed tomographic and scanning electron microscopic scanning as well as histomorphometry was performed on all specimens to obtain detailed qualitative and quantitative information regarding the trabecular microarchitecture of the synostosed suture. Microcomputed tomographic analysis determined the bone volume fraction, trabecular thickness, trabecular separation, bone surface to bone volume ratio, and anisotropy for all specimens. Our results showed significant differences in all of these quantitative measurements when comparing the complete synostotic suture with the open portion of the synostotic sutures (p < 0.05). Microcomputed tomographic stereologic analysis showed evidence of the influence of biomechanical force on the synostotic and open portions of the synostotic sutures. Results of scanning electron microscopy show a definite qualitative difference in the trabecular pattern of the partial and complete synostotic suture when compared with the open portion of the synostotic sagittal suture. In this study, we performed both qualitative and quantitative comparisons of the ultrastructure of the complete synostotic and nonsynostotic sagittal sutures using stereologic and histomorphometric techniques. We also demonstrated evidence of the influence of biomechanical force on the synostotic sagittal suture. Finally, we established a link between the pathologic changes transforming normal suture fusion to craniosynostosis and concurrent changes in both the vector and direction of suture fusion initiation.

Volume maintenance of onlay bone grafts in the craniofacial skeleton: micro-architecture versus embryologic origin.

The superior volume maintenance of membranous over endochondral bone has been shown in several studies and provides the basis for its preferred clinical use as an onlay grafting material in the craniofacial skeleton. The scientific rationale for this seeming embryologic advantage, however, has never been proven. Our hypothesis is that the pattern of onlay bone graft resorption is primarily determined by a graft's micro-architecture (relative cortical and cancellous composition) rather than its embryologic origin (membranous versus endochondral). Twenty-five adult New Zealand, White rabbits were used for this study. Eight animals were killed at 3 weeks, eight animals at 8 weeks, and nine animals at 16 weeks. Three graft types were placed onto each rabbit cranium: cortical bone graft of membranous origin and cortical and cancellous bone graft of endochondral origin. Fluorochrome markers were injected into all living rabbits at 1, 6, and 14 weeks. Microcomputed tomography scanning was performed on all of the bone grafts to determine postsacrifice volumes and to obtain detailed information regarding the bone graft's trabecular architecture. In addition, specimens were examined histologically. Volume analysis showed a statistically greater resorption rate in the cancellous endochondral bone graft than in either the endochondral or membranous cortical bone grafts (p < 0.05) for all time points. In addition there was no significant difference in the resorption rates between the endochondral and membranous cortical bone grafts. A post-test power analysis (alpha = 5 percent) of the volume data comparing the two types of cortical bone grafts showed that a difference in resorption of 8.9 percent would be detected with a 90-percent probability. Previous studies, which have shown a seeming superiority of membranous over endochondral bone grafts, used composite grafts composed of both cortical and cancellous portions. By separating these components, we have shown that cortical bone grafts maintain their volumes significantly better than cancellous bone grafts. In addition, we found no statistical difference in the resorption rates between the two cortical onlay bone grafts of different embryologic origins, a finding that has never been previously published. From our results, we believe cortical bone to be a superior onlay grafting material, independent of its embryologic origin. We believe these results challenge the currently accepted theories of bone graft dynamics and may lead to a change in the way clinicians approach bone graft selections for craniofacial surgery.

Pediatric facial fractures: analysis of differences in subspecialty care.

At the University of Michigan, the pediatric facial fracture call schedule rotates through the plastic surgery, otolaryngology, and oral surgery services. This situation provides an opportunity to evaluate differences in the management of pediatric facial fractures between subspecialty groups. At this hospital, a retrospective review of all pediatric facial fracture cases within a 5-year period was undertaken. Sixty patients with 82 facial fractures were studied along subspecialty lines. Differences in patient groups, practice patterns, and treatment strategies based on subspecialty assignment were found. Overall treatment followed traditional lines, with plastic surgeons involved in all types of pediatric facial fractures, whereas otolaryngology and oral surgeons were more limited in their operative scope, despite equal call responsibilities. It is believed that the managed care arena is a competitive environment in which it will be important to know the strengths and weaknesses of the plastic surgery specialty, as well as those of competing specialties, as patient contracts are negotiated. The overlap of plastic surgery, otolaryngology, and oral surgery in the care of facial trauma could result in plastic surgeons being left off of managed care participant lists. This study highlights plastic surgeons as efficient deliverers of quality care for pediatric facial fractures. Although the treatment of these fractures has fallen into the duties shared by all three subspecialties, data such as those presented here should strengthen our ability to succeed in the evolving environment of managed care.

Biomechanical study of sternal closure using rigid fixation techniques in human cadavers.

BACKGROUND: We believe rigid plate fixation may be superior to wire fixation in sternal closure, as rigid fixation used in the craniofacial skeleton has shown greater stability, lower postoperative pain, and accelerated bone healing. We hypothesize that sterna fixed with titanium plates are more stable mechanically than sterna fixed with wires. METHODS: The sterna from human cadavers were used in this two-phased study. Phase I compared wires to four-hole titanium straight plates. Phase II compared wires to four-hole titanium custom H plates. The sterna were tested biomechanically using all fixation methods. RESULTS: Phase I showed no statistically significant difference in the stiffness or lateral displacement between the wired and straight plated sterna. Phase II showed a statistically significant greater stiffness (p < 0.05) and less lateral displacement (p < 0.05) in the custom plated sterna over the wired sterna. CONCLUSIONS: Our results showed that custom titanium H plates were superior to wire fixation. Furthermore, our results established the importance of plate configuration in sternal fixation. Our study may have beneficial clinical implications, as decreased motion at the sternotomy site could mean less postoperative pain, a decreased incidence of infection, and accelerated bone healing.