Declining Rates of Legg-Calvé-Perthes Surgery in the United States: National Trends Using the Kids' Inpatient Database and Pediatric Health Information System

BACKGROUND

In 2004 and 2008 two large prospective, multicenter studies were published which resulted in improved understanding of operative indications for the treatment of Legg-Calvé-Perthes disease (LCPD) based on patient age, disease severity, and resultant radiographic outcomes. The primary aim of this study is to evaluate the trends in surgical management of LCPD in the United States prior, and subsequent to, the publication of these landmark studies.

METHODS

Cross-sectional retrospective analysis of US pediatric hospitalizations for the surgical management of LCPD was conducted using the Kids' Inpatient Database from 2000 to 2016. Patients 12 years of age and younger were included who had a primary admission diagnosis of LCPD and a LCPD-related procedure during the hospitalization. Data was subsequently weighted to produce national-level estimates and variables pertaining to patient age group, procedure, demographics, and hospital characteristics were analyzed. In a post hoc analysis, the results of the Kids' Inpatient Database were also corroborated with the Pediatric Health Information System database.

RESULTS

A weighted sample of 2786 LCPD surgical admissions met inclusion and exclusion criteria; 11.2% of surgical admissions were patients below 6 years of age, 35.9% were 6 to 8 years of age, and 52.9% were above 8 years of age. There was a significant decrease in admissions for surgical management of LCPD in all age groups over time, however there was no appreciable change in the proportion of LCPD surgical admissions performed among the above 8 to below 12, above 6 to below 8, or below 6 years age groups. Femoral osteotomy remained the most common surgical procedure, while other osteotomy types, including pelvic and unspecified osteotomies involving the hip, decreased over time ( P <0.001).

CONCLUSIONS

There is a decreasing rate of hospital admissions for LCPD surgery since 2000, perhaps indicating a decline in incidence of disease. Furthermore, despite evidence supporting LCPD surgical outcomes related to patient age, there has been no change in the proportion of patients undergoing surgery by age group over time.

LEVEL OF EVIDENCE

Level III-retrospective study.

A dedicated surgical team for posterior spinal fusion in patients with adolescent idiopathic scoliosis improves OR efficiency

PURPOSE

Standardized care pathways for adolescent idiopathic scoliosis (AIS) patients undergoing PSF improve clinical outcomes. We hypothesized that having dedicated spine personnel would decrease surgical time and improve clinical outcomes.

METHODS

367 patients with AIS had a PSF within a standardized perioperative care pathway. Cases with 1-3 dedicated spine team members (any combination of circulating nurse, surgical technologist, and anesthesiologist) were compared to teams with none. The impact of individual members was also analyzed. Parametric or non-parametric tests were used for each outcome based on the distribution of the data points. These included one-way ANOVA models, Kruskal-Wallis tests, and Fisher's exact tests.

RESULTS

Surgical time and total OR time were significantly decreased with the participation of each additional dedicated team member resulting in 43.86 min less surgical time and 50.8 min less total OR time when three team members were present compared to no team members. If the nurse was a spine member, the surgical time was lower (p = 0.037). If the technologist was a team member, the surgical time and total OR time were lower (p = 0.002 and p = 0.001, respectively). Lastly, if the anesthesiologist was a member of the team, the anesthesia time was lower (p = 0.003). No significant clinical differences were observed.

CONCLUSION

Having dedicated surgical team members decreases surgical and total OR time for AIS patients undergoing PSF, and this OR efficiency improves as the dedicated team is more robust. OR surgical teams did not influence clinical outcomes. Hospitals should strongly consider developing surgical teams to improve OR efficiency of PSF cases.

1311. Associations Between Microbiological Diagnoses and Clinical Outcomes in Children with Acute Hematogenous Osteomyelitis: A Retrospective Cohort Study

Background

Acute hematogenous osteomyelitis (AHO) affects about 2-13 children per 100,000 in developed countries each year. Staphylococcus aureus is the most common causative pathogen of AHO and, due to antibiotic resistant strains of this species, a microbial diagnosis is often desired. Blood and bone cultures may identify causative pathogens and determine antibiotic susceptibilities but obtaining bone cultures carries risks. The benefit to patients of having a pathogen identified is disputed and further research is required to address this question. The objectives of this study were to determine if length of stay differs between culture-negative and culture-positive patients and to determine if odds of receiving 3 or more unique antibiotics differs between culture-negative and culture-positive patients.

Methods

Data were retrospectively abstracted from medical records of pediatric patients with a clinician’s diagnosis of AHO admitted to Children’s National Hospital (CNH) between January 1, 2010 – June 30, 2020. Baseline characteristics, treatment, and outcomes were described. For culture-negative and culture-positive AHO patients, length of stay and odds of receiving 3 or more unique antibiotics were compared using multiple linear regression and multiple logistic regression, respectively.

Results

Of 367 included patients, 210 had a positive culture result about 83% of which were identified as S. aureus. Culture-negative patients were associated with a 6.45-day shorter length of stay compared to culture-positive patients, adjusting for age, peak C-reactive protein (CRP), and surgery (p = 0.02). Culture-negative patients had 0.196 times the odds of receiving 3 or more unique antibiotics than culture-positive patients, adjusting for age, peak CRP, and surgery (95% CI: 0.114, 0.336).

Conclusion

Among AHO patients admitted to CNH, being culture-negative was associated with shorter length of stay and lower odds of receiving 3 or more unique antibiotics.

Disclosures

All Authors: No reported disclosures.

Outpatient Bryant's Overhead Traction Does Not Affect the Rate of Open Reduction or Avascular Necrosis in Developmental Dislocation of the Hip

BACKGROUND

The efficacy of preliminary traction to increase the likelihood of closed reduction and/or decrease the incidence of avascular necrosis in the management of developmental dysplasia of the hip (DDH) is controversial. We sought to document compliance with and effectiveness of Bryant's outpatient traction in patients with idiopathic DDH.

METHODS

Patients presenting between 6 and 24 months of age with idiopathic irreducible DDH were prospectively enrolled in the study. Prereduction outpatient traction was prescribed at participating surgeons' preference and parents' expressed willingness to comply with a traction protocol of at least 14 hours/day for 4 weeks. Traction hours were documented using a validated monitor; parents also reported average daily usage. Rate of successful closed reduction and evidence of capital epiphyseal growth disturbance 1 year' and 2 years' postreduction were documented.

RESULTS

Ninety-six patients with 115 affected hips were enrolled. Reliable recorded traction hours were obtained in 31 patients with 36 affected hips. Defining compliance as 14 hours/day average use, 14 of 31 patients (45.2%) were compliant, 2 (6.5%) admitted noncompliance, while 15 (48.2%) claimed to be compliant, but were not. Overall, 68/115 hips (59.0%) were closed reduced. Age at treatment was the only demographic characteristic associated with an increased incidence of closed reduction (11.7 vs. 14.6 mo, P<0.01). Successful closed reduction was achieved in 10/16 hips (62.5%) of compliant patients, 12/20 (60.0%) of noncompliant patients, and 43/72 (59.7%) of no-traction patients. Irregular ossific nucleus development was noted 1-year postindex reduction in 5/16 (31.3%) of complaint-patient hips and 25/92 (27.2%) of noncomplaint and no-traction hips. Distorted proximal femoral epiphysis was noted at 2 years postreduction in 2/15 hips (13.3%) of compliant patients and 15/52 hips (28.8%) in noncompliant and no-traction patients. None of these differences was statistically significant.

CONCLUSIONS

Parent-reported use of outpatient traction is unreliable. Four weeks of outpatient overhead Bryant's traction did not affect the rate of closed reduction or avascular necrosis in late-presenting DDH in this cohort.

LEVEL OF EVIDENCE

Level II-prospective cohort.

Posterior Tibial Slope is Increased in Patients With Tibial Tubercle Fractures and Osgood-Schlatter Disease

BACKGROUND

Osgood-Schlatter disease (OSD) and tibial tubercle fractures are pathologies that affect the tibial tubercle apophysis in preadolescents and adolescents. Anatomic alignment of the proximal tibia may explain why some children develop OSD or sustain tibial tubercle fractures and some do not. Recent data has shown an association between posterior tibial slope angle (PTSA) and both OSD and proximal tibia physeal fractures. In this study, we compare radiographic parameters between patients with non-OSD knee pain, knees with OSD, and knees with tibial tubercle fracture to elucidate a difference between these groups.

METHODS

Patients treated for OSD, tibial tubercle fractures, and knee pain, from 2012 to 2018, were retrospectively reviewed. Radiographic parameters for each study group included PTSA, anatomic lateral distal femoral angle, anatomic medial proximal tibial angle, patellar articular height, and the distance from the inferior aspect of the patellar articular surface. Caton-Deschamps index was then calculated. Demographic data was collected including age, sex, and body mass index. Demographic and radiographic data was compared using analysis of variance tests, χ2 tests, 2-sample t tests, and multiple linear regression.

RESULTS

Two hundred fifty-one knees in 229 patients met inclusion criteria for the study. In all, 76% were male and the average age of the overall cohort was 14 years old. In patients with tibial tubercle fractures, the majority of fractures were Ogden type 3b (65%). After controlling for demographic variability, average PTSA in the fracture cohort was significantly greater than that in the control cohort (β=3.49, P<0.001). The OSD cohort had a significantly greater posterior slope (β=3.14) than the control cohort (P<0.001). There was no statistically significant difference between the fracture and OSD cohorts. There was also no difference in Caton-Deschamps index between the 2 study groups when compared with the control group.

CONCLUSION

This study demonstrates that patients with tibial tubercle fractures and patients with OSD have an increased PTSA when compared with the control group. This information adds to the body of evidence that increased tibial slope places the proximal tibial physis under abnormal stress which may contribute to the development of pathologic conditions of proximal tibia such as OSD and tibial tubercle fractures.

LEVEL OF EVIDENCE

Level III; retrospective comparative study.

Ammonia removal from thermal hydrolysis dewatering liquors via three different deammonification technologies

The benefits of deammonification to remove nitrogen from sidestreams, i.e., sludge dewatering liquors, in municipal wastewater treatment plants are well accepted. The ammonia removal from dewatering liquors originated from thermal hydrolysis/anaerobic digestion (THP/AD) are deemed challenging. Many different commercial technologies have been applied to remove ammonia from sidestreams, varying in reactor design, biomass growth form and instrumentation and control strategy. Four technologies were tested (a deammonification suspended sludge sequencing batch reactor (S-SBR), a deammonification moving bed biofilm reactor (MEDIA), a deammonification granular sludge sequencing batch reactor (G-SBR), and a nitrification suspended sludge sequencing batch reactor (N-SBR)). All technologies relied on distinct control strategies that actuated on the feed flow leading to a range of different ammonia loading rates. Periods of poor performance were displayed by all technologies and related to imbalances in the chain of deammonification reactions subsequently effecting both load and removal. The S-SBR was most robust, not presenting these imbalances. The S-SBR and G-SBR presented the highest nitrogen removal rates (NRR) of 0.58 and 0.56 kg N m^-3 d^-1, respectively. The MEDIA and the N-SBR presented an NRR of 0.17 and 0.07 kg N m^-3 d^-1, respectively. This study demonstrated stable ammonia removal from THP/AD dewatering liquors and did not observe toxicity in the nitrogen removal technologies tested. It was identified that instrumentation and control strategy was the main contributor that enabled higher stability and NRR. Overall, this study provides support in selecting a suitable biological nitrogen removal technology for the treatment of sludge dewatering liquors from THP/AD.

Association between perioperative surgical home implementation and transfusion patterns in adolescents with idiopathic scoliosis undergoing spinal fusion

BACKGROUND

Blood transfusions in patients with adolescent idiopathic scoliosis after fusion have been associated with increased morbidity, mortality, and cost.

OBJECTIVE

The aim of this study was to evaluate the association between implementation of blood-conservation strategies within the perioperative surgical home on transfusion rates for patients with adolescent idiopathic scoliosis undergoing spinal fusion.

METHODS

Two hundred and thirteen patients (44 preperioperative surgical home, 169 postperioperative surgical home) who underwent posterior spine fusion for adolescent idiopathic scoliosis between 23 June 2014, and 30 July 2017, were enrolled in this case control study. The perioperative surgical home implemented in March 2015 involved evidence-based perioperative interventions to create a standardized clinical pathway including judicious use of crystalloid management, restrictive transfusion strategy, routine use of cell saver, and standardized administration of anti-fibrinolytics. The primary outcome was odds of perioperative transfusion. Secondary outcomes included volumes of crystalloid, albumin, cell saver, packed red blood cells as well as calculated blood loss. Other variables that were documented included antibrinolytic total dose, mean arterial pressure, temperature, laboratory values, intrathecal morphine dosing, and surgical time. Statistical methods included t test and logistic regression.

RESULTS

For the postperioperative surgical home, the odds of perioperative transfusion were 0.30 (95% CI 0.13-0.70), as compared to preperioperative surgical home. In terms of secondary outcomes, calculated blood loss was significantly lower in the postperioperative surgical home patients (27.0 mL/kg preperioperative surgical home vs 22.8 mL/kg postperioperative surgical home; mean difference = -0.24 [-0.44, -0.04]). Although no difference was noted in the amount of intraoperative cell saver or albumin administered, a reduction was noted in mean intraoperative crystalloid given postperioperative surgical home (41.4 mL/kg ± 20.4 mL/kg preperioperative surgical home vs 28.0 mL/kg ± 13.7 mL/kg postperioperative surgical home; log mean difference = 0.37 [95% CI 0.21-0.53], P < 0.001). Postperioperative surgical home patients also had a significantly higher temperature nadir (mean difference = -0.47 [95% CI -0.70 to -0.23]; P < 0.001), received a significantly higher total anti-fibrinolytic dose (mean difference = -3939 [95% CI -5364 to -2495]; P < 0.001), and were exposed to shorter surgical times (mean difference = 0.72 [95% CI 0.36-1.09]; P < 0.001).

CONCLUSIONS

Implementation of blood-conservation strategies as part of a perioperative surgical home for patients with adolescent idiopathic scoliosis undergoing posterior spine fusion resulted in significant decrease in perioperative blood transfusions.

Effectiveness and Sustainability of a Standardized Care Pathway Developed with Use of Lean Process Mapping for the Treatment of Patients Undergoing Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

BACKGROUND

Recent changes in health care have begun to shift the industry from a volume-based to a value-based focus. This shift has led to standardized care pathways that decrease care variability, improve outcomes, and decrease cost. Although numerous studies have described standardized pathways for adolescent idiopathic scoliosis (AIS), few have demonstrated sustainability. We report the effectiveness and sustainability of a standardized care pathway for patients undergoing posterior spinal fusion for AIS.

METHODS

A standardized care pathway was developed and implemented (in March 2015) at our pediatric hospital for all patients undergoing posterior spinal fusion for AIS. This pathway was developed with use of the Lean process mapping technique to create an evidence-based protocol for preoperative, operative, postoperative, and post-discharge care. The 44 patients managed prior to implementation of the pathway (pre-pathway group) were compared with the 169 patients managed after implementation (post-pathway group). The post-pathway group was divided into 5 cohorts, each representing a 6-month time period. Clinical outcomes (pain scores, medication requirements, transfusions) and efficiency metrics (length of stay) were used to determine pathway sustainability.

RESULTS

The pre-pathway group included patients managed in the 8 months prior to implementation (July 2014 to February 2015) and the post-pathway group included patients who underwent surgery from March 2015 to July 2017, divided into 5 cohorts representing 6 months each. Patients in the post-pathway group had lower postoperative pain scores, and used significantly less opioids at each time interval, compared with the pre-pathway group. Perioperative transfusion requirements and postoperative length of stay were significantly lower across all post-pathway cohorts compared with the pre-pathway group. There were no significant differences in clinical results among the 5 post-pathway cohorts.

CONCLUSIONS

Implementation of a standardized care pathway developed with use of Lean process mapping demonstrated effective and sustained improvements to the care of patients with AIS, as well as decreased postoperative length of stay. These outcomes have been maintained over 2.5 years, indicating that high-quality care for patients with AIS undergoing spinal fusion can be achieved and sustained with use of a standardized care pathway.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Quantifying the performance of a hybrid anion exchanger/adsorbent for phosphorus removal using mass spectrometry coupled with batch kinetic trials

Increasingly stricter phosphorus discharge limits represent a significant challenge for the wastewater industry. Hybrid media comprising anionic exchange resins with dispersions of hydrated ferric oxide nanoparticles have been shown to selectively remove phosphorus from wastewaters, and display greater capacity and operational capability than both conventional treatment techniques and other ferric-based adsorbent materials. Spectrographic analyses of the internal surfaces of a hybrid media during kinetic experiments show that the adsorption of phosphorus is very rapid, utilising 54% of the total capacity of the media within the first 15 min and 95% within the first 60 min. These analyses demonstrate the importance of intraparticle diffusion on the overall rate in relation to the penetration of phosphorus. Operational capacity is a function of the target effluent phosphorus concentration and for 0.1 mg P L^-1, this is [Formula: see text], which is 8-13% of the exhaustive capacity. The adsorbed phosphorus can be selectively recovered, offering a potential route to recycle this important nutrient. The main implication of the work is that the ferric nanoparticle adsorbent can provide a highly effective means of achieving a final effluent phosphorus concentration of 0.1 mg P L^-1, even when treating sewage effluent at 5 mg P L^-1.

Treatment of hip subluxation in skeletally mature patients with cerebral palsy

Hip subluxation is common in children with spastic cerebral palsy. Most physicians favor intervention to treat hip subluxation in skeletally immature patients with cerebral palsy. However, treatment in skeletally mature patients with cerebral palsy is controversial. The goal of this study was to evaluate radiographic and clinical outcomes after hip reconstruction in skeletally mature patients with cerebral palsy. The authors performed a retrospective review of all skeletally mature patients (n=20) with cerebral palsy who underwent hip surgery for subluxation at the authors' institution between 2005 and 2011. Charts were reviewed for demographic characteristics, procedure, follow-up, and complications. Acetabular index, migration index, and neck-shaft angle were measured on preoperative and most recent radiographs. Average follow-up was 2.2 years. Average migration index for the entire group improved from 57% to 20% (P<.0001). Of patients who had all radiographic abnormalities addressed at surgery (varus derotational femoral osteotomy for neck-shaft angle >135°, open reduction for migration index >50%, and acetabular osteotomy for acetabular index >25°), 91% had a final migration index of less than 25%. In patients who did not have all radiographic abnormalities addressed, 33% had a migration index of less than 25% at final follow-up. No intraoperative complications occurred; however, 13 patients had at least 1 postoperative complication. Hip subluxation in skeletally mature patients with cerebral palsy is difficult to treat and is associated with a high incidence of complications. The likelihood of a successful outcome appears to be related to the appropriateness of the surgical procedure. When all radiographic abnormalities were addressed during surgery, a successful radiographic outcome at final follow-up was much more likely than when intervention was less comprehensive.

Selective removal of phosphate from wastewater using hydrated metal oxides dispersed within anionic exchange media

Hydrated ferric oxide (HFeO), hydrated zirconium oxide (HZrO) and hydrated copper oxide (HCuO) were immobilized within a microporous anion exchange resin (IRA-400), forming hybrid media for enhanced phosphate removal from aqueous systems. Empirical data from batch kinetic trials fitted the pseudo second order mechanism for chemical adsorption and each media was rate limited by intraparticle diffusion overall. These models were also used to predict the adsorption rate constants and the equilibrium adsorption capacities, which ranged from 26.51 to 30.44 mgP g(-1), and from 24.15 to 27.90 mgP g(-1) of media for the calculated and experimental capacities, respectively. The phosphate adsorption behavior by the hybrid materials fit both the Langmuir and Freundlich adsorption isotherms (R(2)>0.94), and the maximum adsorption capacities were 111.1 mgP g(-1) for HFeO, 91.74 mgP g(-1) for HZrO and 74.07 mgP g(-1) for HCuO. The effect of competing ions such as sulfate reduced these capacities to 18.52 mgP g(-1) for HFeO and 18.97 mgP g(-1) for HZrO. Despite this decrease, HFeO was capable of reducing the phosphate in a real wastewater matrix by 83%, and the HZrO media was able to reduce it by 86%, suggesting that such hybrid media have the potential for application at full scale.

Characterization of full-scale carbon contactors for siloxane removal from biogas using online Fourier transform infrared spectroscopy

In this study, online Fourier transform infrared (FTIR) spectroscopy has been used to generate the first comprehensive characterization of full-scale carbon contactors for siloxane removal from biogas. Using FTIR, two clear operational regions within the exhaustion cycle were evidenced: an initial period of pseudo-steady state where the outlet siloxane concentration was consistently below the proposed siloxane limits; and a second period characterized by a progressive rise in outlet siloxane concentration during and after breakthrough. Due to the sharp breakthrough front identified, existing detection methods (which comprise field sampling coupled with laboratory-based chromatographic determination) are insufficiently responsive to define breakthrough, thus carbon contactors currently remain in service while providing limited protection to the combined heat and power engine. Integration of the exhaustion cycle to breakthrough identified average specific media capacities of 8.5-21.5 gsiloxane kg(-1)GAC, which are lower than that has been reported for vapour phase granular activated carbon (GAC). Further speciation of the biogas phase identified co-separation of organic compounds (alkanes and aromatics), which will inevitably reduce siloxane capacity. However, comparison of the five full-scale contactors identified that greater media capacity was accessible through operating contactors at velocities sufficient to diminish axial dispersion effects. In addition to enabling significant insight into gas phase GAC contactors, the use of FTIR for online control of GAC for siloxane removal is also presented.

Intrathecal Anomalies in Presumed Infantile Idiopathic Scoliosis: When Is MRI Necessary?

STUDY DESIGN

Retrospective review.

OBJECTIVE

To determine the rate of abnormal magnetic resonance imaging (MRI) findings in patients with presumed infantile idiopathic scoliosis (IIS) and the rate of neurosurgical intervention in those patients, and to develop a guideline concerning when to obtain an MRI.

SUMMARY OF BACKGROUND DATA

The reported rate of intrathecal anomalies associated with presumed IIS varies in the literature (12% to 50%). Conclusions have led to conflicting recommendations concerning when an MRI is indicated.

METHODS

After appropriate internal review board approval, the authors retrospectively reviewed the medical records of patients from a single institution meeting the inclusion criteria: presumed idiopathic curve with a magnitude of ≥20°, age <36 months at diagnosis, normal neurologic examination, and presentation between 2002 and 2010. The authors reviewed the MRI findings, whether neurosurgical intervention took place, and the orthopedic treatment course (observation, brace, cast, or surgery).

RESULTS

A total of 56 patients were identified and reviewed; 43 had had an MRI. Seven of 43 patients were found to have an anomaly (16.2%). A fatty filum was identified in 2 patients, a syrinx in 3, Chiari I malformation in 2, and a tethered cord in 1 (this patient also had a syrinx). Two of the 7 patients required neurosurgical intervention (28%). Patients who did not have an MRI were statistically younger, had smaller Cobb angles, and required less orthopedic treatment.

CONCLUSIONS

The incidence of intrathecal anomalies (16.2%) at the authors' institution was similar to previously published reports; however, the need for neurosurgical intervention was significantly lower in this study (28%). For younger patients with small curves (<30°) who do not require orthopedic treatment, MRI under sedation can be delayed or avoided. Clinical judgment should be the determinant for whether to use MRI when evaluating patients with presumed IIS.

A biomechanical comparison of multidirectional nail and locking plate fixation in unstable olecranon fractures

BACKGROUND

The main theoretic advantage of proximal olecranon fracture intramedullary fixation is decreased soft-tissue irritation and, potentially, less subsequent hardware removal. Despite this possible benefit, questions remain as to whether intramedullary devices are capable of controlling olecranon fractures to the same extent as locking plates. This study evaluates the ability of a novel multidirectional locking nail to stabilize comminuted fractures and directly compares its biomechanical performance with that of locking olecranon plates.

MATERIALS AND METHODS

We implanted 8 stainless steel locking plates and stainless steel intramedullary nails to stabilize a simulated comminuted fracture in 16 fresh-frozen cadaveric elbows. Flexion-extension, varus-valgus, gap distance, and rotational 3-dimensional angular displacement analysis was conducted over a 60° motion arc (30° to 90°) to assess fragment motion through physiologic cyclic arcs of motion and failure loading. Displacements in all planes were compared.

RESULTS

Both implants showed less than 1° of motion in all measured planes and allowed less than 1 mm of gapping through all loads tested until ultimate failure. All failures occurred by sudden, catastrophic means. The mean failure weight for the nail was 14.4 kg compared with 8.7 kg for the plate (P = .02). The nail survived 1102 cycles, whereas the plate survived 831 cycles (P = .06).

CONCLUSION

In simulated comminuted olecranon fractures, the multidirectional locking intramedullary nails sustained significantly higher maximum loads than the locking plates. The two implants showed no significant differences in fragment control or number of cycles survived. Surgeons can expect the multidirectional locking nails to stabilize comminuted fractures at least as well as locking plates.

Quantifying and comparing torsional strains after olecranon plating

PURPOSE

Any torsion experienced at a fracture site will directly translate into shearing forces and has been regarded as detrimental to healing. The purpose of this study was to determine which plating system currently on the market controls torsional forces about comminuted olecranon fractures most effectively.

METHODS

Five olecranon plates (Acumed, Synthes-SS, Synthes-Ti, ITS/US Implants and Zimmer) were implanted to stabilise a simulated comminuted fracture pattern in 50 fresh-frozen, cadaveric elbows. All specimens were evaluated by dual energy X-ray absorptiometry (DXA) scan to determine bone density. Three-dimensional displacement analysis was conducted to assess fragment motion through physiologic cyclic arcs of motion. The specimens were cycled through progressive physiologic loads (0.18-5.6 kg). Movements of the fragments were statistically compared amongst the different implants using one-way analysis of variance (ANOVA) and Tukey Honestly Significant Difference (HSD) post hoc comparisons with a critical significance level of α=0.05.

RESULTS

DXA bone mineral densities (BMDs) ranged from 0.465 to 0.927, with an average of 0.714. The Acumed, Synthes-SS, Synthes-Ti and Zimmer plates allowed <1° of torsion up to 1.6 kg of load. The differences between these plates at this load were not statistically significant. The ITS/US Implants plate, however, allowed significantly more torsion above loads of 2.6 kg (p=0.045) compared with all other plates. The ITS/US Implants plate allowed over 2° of torsion at 2.6 kg (p=0.012), and nearly 3° at 3.6 kg (p=0.045). The Zimmer plate consistently allowed more torsion than the Acumed plate or either of the Synthes plates, but the differences were not statistically significant.

CONCLUSION

Regardless of which olecranon plate is used, the authors recommend limiting postoperative rehabilitation loads to below 1.6 kg in an effort to minimise the detrimental effects of torsion on healing. If loads over 1.6 kg are anticipated, the authors recommend the use of the Acumed plate or either of the Synthes plates.

Increasing the enrolment of rural applicants to the faculty of medicine and addressing diversity by using a priority matrix approach to assign values to rural attributes

In an external review of the admissions process for the Faculty of Medicine, University of Manitoba, Canada, it was suggested that admissions policies be modified to increase the enrolment of students more likely to practise in rural locations, by selecting a cohort of students with attributes reflecting potential for rural practice. A broad-based Working Group devised a framework for scoring personal attributes reflecting a potential for living and working in rural areas. This framework, based on established characteristics reported in the literature, valued applicants who had rural connections, a history of rural employment, a history of rural community service, or a combination of these attributes. Relative weights for the attributes were determined using a priority matrix approach. Historic admissions data, comprising applicants' rural origin (defined only by location of high school graduation), composite scores, and ranking, were reanalyzed to identify the magnitude of numerical constants that, when applied to composite scores, enhanced the relative ranking of eligible rural-origin applicants. This resulted in a hypothetical 29%-33% increase in the number of rural-origin students in incoming classes in those years. In the inaugural year of implementation of the policy and methodology, 60 admission offers (44.1%) were made to applicants with one or more rural attributes. Without adjustments, only 49 applicants with rural attributes (36%) would have been offered admission. This methodology resulted in a 22.4% increase in admission offers to applicants with rural attributes, and ushered in an incoming class that was more representative of the province's rural-urban demographics than in previous years. This methodology, although focused on rurality, could be equally applicable to any attribute, and to achieve greater diversity and equity among medical school applicants.

Methylcobalamin's full- vs. "half"-strength cobalt-carbon sigma bonds and bond dissociation enthalpies: A >10(15) Co-CH3 homolysis rate enhancement following one-antibonding-electron reduction of methlycobalamin

Methylcobalamin (MeCbl, MeB12) thermolyzed in ethylene glycol from 120 to 141 degrees C with 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) as a Me(.) trap gives the homolysis products Co(II)B12 and TEMPO-Me quantitatively. The 5,6-dimethylbenzimidazole axial-base-off-base-on equilibrium in ethylene glycol has an enthalpy change of -5.1 (+/-2) kcal mol(-1) and an entropy change of -10.5 (+/-4) cal mol(-1) K(-1), equilibrating between the 5,6-dimethylbenzimidazole-coordinated base-on form and the two distinct yet similar non-coordinated forms: the base-off and the so-called "tuck-in" forms. The MeB12 Co-CH3 homolysis rates indicate an activation enthalpy of 41 +/- 3 kcal mol(-1), an activation entropy of 24 +/- 6 cal mol(-1) K(-1), and an estimated methylcob(III)alamin Co-CH3 bond dissociation energy of 37 +/- 3 kcal mol(-1). This is the strongest Co-C cobamide bond measured. Comparison of the MeCbl homolysis rate constant (10(-19 +/- 4) s(-1)) extrapolated to -30 degrees C with the known reduced-methylcobamide-radical-anion values indicates rate enhancements of 10(22 +/- 4) (at -30 degrees C) following electrochemical reduction, or still over 10(15) at 25 degrees C. Such reduction provides an antibonding electron which weakens the Co-C bond from 37 kcal mol(-1) down to ca. 12 kcal mol(-1). These rate enhancements are greater than the analogous enzyme-induced Co-C cleavage rate enhancements in adenosylcobalamin (Coenzyme B12, AdoCbl)-dependent enzymes. However, electron transfer is not predicted for the mechanism of any adenosylcobalamin-dependent or methylcobalamin-dependent enzymes.

Removal and recovery of phosphate from municipal wastewaters using a polymeric anion exchanger bound with hydrated ferric oxide nanoparticles

A new type of ion exchange media which is highly selective for phosphate, and can be easily regenerated has been investigated. The media consists of hydrated ferric oxide nanoparticles dispersed within the pore structures of polymeric anion exchanger beads. The media combines the durability and mechanical strength of ion exchange resins with the high sorption capacity of ferric oxide for phosphate. The media was trialled in fixed bed mini column experiments with real final effluent from two UK sewage treatment works, one with treatment based on chemical precipitation with iron chloride salts into an activated sludge process (population >250,000), and one based on trickling filter treatment with no specific phosphorus removal process (population <10,000). Results show that the media has high capacity for removing phosphate, reaching capacity at 4000 and 1300 bed volumes for the chemical precipitation and trickling filter works respectively, with performance greatly exceeding that of a standard anion exchanger, Amberlite IRA-410. Also trialled was the media's ability to elute the phosphorus after breakthrough, with the aim of recovering and processing it into a useful product. A one step regenerative process using a single solution containing 4% NaOH and 2% NaCl was passed through the resin bed and the phosphorus concentration of each bed volume leaving the column analysed. 80% of the phosphorus was eluted in the first bed volume. Subsequent tests investigated the performance of the media after successive partial regenerations of one bed volume of the NaOH/NaCl solution. There was no loss of performance observed after ten regeneration cycles, and levels of eluted phosphate were consistently high. These results suggest that the media has high potential for the removal and recovery of phosphate from wastewater streams. Additionally, the small volume of regenerant required translates to a very small operational footprint.

Direct oxidation of guanine and 7,8-dihydro-8-oxoguanine in DNA by a high-valent chromium complex: a possible mechanism for chromate genotoxicity

Intracellular reductive activation of the human carcinogen chromate, Cr(VI), is a necessary step in the formation of DNA lesions that lead to cancer. Reductive activation forms the transient metastable high-valent oxidation state of Cr(V) as a precursor to the final intracellularly stable oxidation state, Cr(III). In this study, we have used a model high-valent Cr(V) complex, N,N'-ethylenebis(salicylideneanimato)oxochromium(V), Cr(V)-Salen, to probe the mechanism of interaction between this oxidation state of chromium and DNA. This interaction was found to be specific toward the oxidation of the nucleic acid base guanine in unmodified single- and double-stranded oligonucleotides as measured by an increased level of DNA strand cleavage at these sites following piperidine treatment. Replacement of a single guanine residue in DNA with a more readily oxidized 7,8-dihydro-8-oxoguanine (8-oxo-G) base allowed for site-specific oxidation at this modified site within the DNA strand by the Cr(V)-Salen complex. HPLC and ESI-mass spectrometry were used to identify the modified guanine base lesions formed in the reaction of this high-valent chromium complex with the 8-oxo-G-containing DNA substrate. Two of these modified base lesions, identified as guanidinohydantoin and spiroiminodihydantoin, were found in the reaction of the Cr(V)-Salen complex with 8-oxo-G-modified DNA, while only one, spiroiminodihydantoin, was formed from oxidation of the 8-oxo-G nucleoside. A primer extension assay using the exo(-) Klenow fragment demonstrated polymerase arrest at the site of these base modifications as well as a high degree of misincorporation of adenine opposite the site of modification. These results suggest that mutations arising from G --> T transversions would predominate with these lesions. The mechanism of damage and base oxidation products for the interaction between high-valent chromium and DNA described herein may be relevant to the in vivo formation of DNA damage leading to cancer in chromate-exposed human populations. These results also suggest how high-valent chromium can act as a cocarcinogen with 8-oxo-G-forming xenobiotics.

Nuclear translocation of cytosolic phospholipase A2 is induced by ATP depletion

Phospholipase A(2) (PLA(2)) enzymes may play a role in cellular injury due to ATP depletion. Renal Madin-Darby canine kidney cells were subjected to ATP depletion to assess the effects of cellular energy metabolism on cytosolic PLA(2) (cPLA(2)) regulation. ATP depletion results in a decrease in soluble cPLA(2) activity and an increase in membrane-associated activity, which is reversed upon restoration of ATP levels by addition of dextrose. In ATP-depleted cells cPLA(2) mass shifts from cytosol to nuclear fractions. GFP-cPLA(2) is localized at the nuclear membrane of stably transfected ATP-depleted LLC-PK(1) cells under conditions where [Ca(2+)](i) is known to increase. cPLA(2) translocation does not occur if the increase in [Ca(2+)](i) increase is inhibited. If [Ca(2+)](i) is allowed to increase when ATP is depleted and the cells are then lysed, cPLA(2) remains associated with nuclear fractions even if the homogenate [Ca(2+)] is markedly reduced. In contrast, cPLA(2), which becomes associated with the nucleus when [Ca(2+)](i) is increased using ionophore, readily dissociates from the nuclear fractions of ATP-replete cells upon reduction of homogenate [Ca(2+)]. Okadaic acid inhibits the ATP depletion-induced association of cPLA(2) with nuclear fractions. Thus energy deprivation results in [Ca(2+)]-induced nuclear translocation, which is partially prevented by a phosphatase inhibitor.

The management of ear disease: guidelines for Aboriginal health care programs

Middle ear disease represents a continuing burden of illness for children of circumpolar regions. Uncertainty in management has been shown to create a barrier to timely and adequate treatment. Consistent intervention strategies were sought for the management of middle ear disease in children of the central Canadian Arctic. The current literature was reviewed using MEDLINE. A consensus document was established in consultation with specialists in community medicine, infectious disease, otolaryngology, pediatrics, and community-based care providers. Definitive recommendations and supportive algorithms have been established for management of middle ear disease in Inuit children.

Prevalence of diabetes mellitus and obesity in the Keewatin District of the Canadian Arctic

Through a medical chart review, the prevalence of diagnosed diabetes mellitus in Inuit of the Keewatin District of the Canadian Northwest Territories was determined to be 0.27%. All cases were in adults, and no cases of gestational diabetes were noted. The prevalence and pattern of obesity were determined from measurements of body mass index (BMI), skinfold thickness, and waist-hip ratio obtained during the 1990-91 Keewatin Health Assessment Study. Thirty-one percent of 414 randomly identified adults (29% of men, 37% of women) were overweight (BMI > 27). Central fat patterning was more prevalent in women and less prevalent in men from the Keewatin compared to the general Canadian population. Comparison of skinfold thickness values to published measurements obtained from earlier arctic surveys supports the hypothesis that changes in diet and activity levels associated with urbanization have resulted in increased obesity in the Inuit.

Follow-up of a decentralized colposcopy program for the investigation and management of cervical intraepithelial neoplasia in the central Canadian Arctic

Cervical intraepithelial neoplasia (CIN) is the second leading cause of cancer in Canadian Inuit women, and the incidence ratio in this population is 3.1 times the Canadian average. In 1993 a program was developed in a regional northern health center (Churchill) to provide colposcopy and loop electrosurgery for women in the Keewatin District of the central Canadian Arctic. Data collected prospectively over the following 2.5 years are presented. One hundred and forty-six women were seen in 341 visits. Indication for referral included CIN I on Pap smear (54.1%), CIN II (34.9%), CIN III (9.6%), and carcinoma of the cervix (1.4%). Large loop excision of the transformation zone was performed at a rate of 9.7 procedures per 100 patient visits. Estimated travel cost-savings attributable to this northern program are $299,200 (Canadian). Use of portable colposcopy in patients' home communities is presently being considered in order to provide enhanced accessibility and further cost-effectiveness.

Enhancing diagnostic ultrasound programs utilizing wide-area image management technology

Diagnostic ultrasound in remote sites is limited by attendant delay in interpretation and reporting. Technology advances were incorporated in an ultrasound program based in Churchill, Manitoba, and designed to meet the needs of the Central Canadian Arctic. Still-frame ultrasound images are digitized via a sonographer's picture archiving and communications system (PACS) workstation, and as they are collected they are transmitted over a dial-up Internet protocol network in Dicom 3.0 format to a tertiary care center. Received images are routed to a physician's PACS workstation, where they can be reviewed prior to the patient leaving the remote clinic. The impact of existing technology on a northern ultrasound program is discussed. The implications of technology enhancement are reviewed, with specific reference to remote low bandwidth sites.

Hypervalent chromium mimics reactive oxygen species as measured by the oxidant-sensitive dyes 2',7'-dichlorofluorescin and dihydrorhodamine

Intracellular metabolism of the carcinogen chromate [Cr(VI)] produces the oxidative stress and oxidative DNA damage associated with its genotoxicity. Such oxidative stress has previously been measured by fluorescence using oxidant-sensitive dyes and attributed to the formation of reactive oxygen species (ROS). However, metabolism of Cr(VI) also produces Cr(IV) and Cr(V) which can directly damage biological macromolecules without forming ROS. We used the high-valence chromium species, bis(2-ethyl-2-hydroxybutyrato)oxochromate(V) [Cr(V)-EHBA], to test whether high-valence chromium would also react with the oxidant-sensitive dyes 2',7'-dichlorofluorescin (DCFH) and dihydrorhodamine (DHR). Cr(V)-EHBA caused both dyes to fluoresce over a wide dynamic range and under conditions which indicated that Cr(V) had reacted directly with both dyes without first forming a diffusible radical species. Dimethylthiourea (DMTU) and ethanol did not affect Cr(V)-induced fluorescence in vitro or Cr(VI)-induced fluorescence in A549 cells. Under the same conditions, ethanol and DMTU increased the extent of hydrogen peroxide-induced fluorescence. As chromium-induced fluorescence was unaffected by radical scavengers and was qualitatively different from hydrogen peroxide-induced fluorescence, we conclude that DCF and R123 fluorescence in chromate-treated A549 cells is a qualitative and cumulative measure of intracellular Cr(V) formation and not ROS.

Highly swelling hydrogels from ordered galactose-based polyacrylates

High swelling galactose-based hydrogels have been prepared using a chemoenzymatic procedure. Regioselective acylation of beta-O-methyl-galactopyranoside in nearly anhydrous pyridine with lipase from Pseudomonas cepacia yields the 6-acryloyl derivative (Compound I). Further lipase-catalysed acylation of the monoacrylate derivative in nearly anhydrous acetone yielded 2,6-diacryloyl-beta-O-methyl galactopyranoside (Compound II) that can act as a cross-linker with a structure similar to that of the sugar-based monomer. The high selectivity of enzyme catalysis yielded apparently highly regular hydrogel networks with swelling ratios at equilibrium ranging from 170 to 1100. elastic moduli ranging from 0.005 to 0.088 MPa and calculated mesh sizes ranging from 1160 to 6600 A. These values are far higher than conventional uncharged or lightly charged hydrogels at similar elastic moduli. Gel swelling was fast, with 75% of the equilibrium swelling value reached in a fractional time of 0.17. Non-selective chemical acryloylation of beta-O-methyl galactopyranoside followed by polymerization yielded a far lower-swelling hydrogel than that obtained using selective enzyme catalysis. These results indicate that the highly regular polymer structure achieved by regioselective enzyme-catalysed acylation yields relatively strong and highly swellable materials. Sugar-based hydrogels, such as those described herein, may find particular use as biomaterials because of their high water content, homogeneity, stability and expected non-toxicity. A wide range of pore sizes can be attained, suggesting that they may also be especially useful as matrices for enzyme immobilization and controlled delivery of biological macromolecules.

Diffusion and transfer of antibody proteins from a sugar-based hydrogel

Diffusion of antibody protein from hydrogel films and hydrogel encapsulated in a microcapillary was studied. Thin hydrogel films were formed by crosslinking 6-acryloyl-B-O-methylgalactoside with N,N'-methylene-bis-acrylamide and the diffusive transport of monoclonal antimouse IgG-FITC into and out of the hydrate films was measured. Diffusion coefficients in 2 and 4% crosslinked hydrogel films were measured. The measured diffusion constants determined for IgG in both the 2 and 4% hydrogel films were comparable to the free diffusion of IgG in bulk water (Dmean approximately 10(-7) cm2/s). In addition, 2% crosslinked hydrogels were prepared in a capillary tube and the transport of antimouse IgG-FITC into and out of the hydrated hydrogel was measured. Kinetic analysis indicated that the protein transport through the capillary hydrogel was faster than would be expected for a simple diffusion process. Finally, by utilizing the diffusion of antibody from the capillary hydrogel, transfer of antibody to a silica surface was demonstrated. A capillary hydrogel loaded with antimouse IgG-FITC was used to transfer the protein to a silica surface forming a 30-micron spot of antibody, which was imaged using fluorescence microscopy. These results may lead to the development of a nonlithographic method of patterning antibodies on surfaces for use in integrated microimmunosensors.

Enzymology in monophasic organic media

Over the past year, an important area of research has been directed towards the fundamental aspects of enzymes and new applications of enzymology in monophasic organic media. Much of this research has focused on the factors that influence enzymatic catalysis in monophasic organic solvents, including the importance of enzyme-associated water, and the effect of organic solvents on enzyme structure and thermodynamic features. From an applications perspective, new advances in the use of enzymes in organic and polymer syntheses and optical resolutions have been made.

Coenzyme AdoB12 vs AdoB12.-homolytic Co-C cleavage following electron transfer: a rate enhancement greater than or equal to 10(12)

Comparison of the 25 degrees C Co-C bond homolysis rate constant of adenosyl-cobalamin (coenzyme B12) vs that for electrochemically reduced adenosyl-cobalamin radical anion indicates a rate enhancement of at least 10(12 +/- 2) upon the addition of one antibonding electron. Even though electrochemical reduction promotes Co-C homolysis by virtually the same amount as the 10(12 +/- 1) enzymic activation seen for adenosylcobalamin, electron-transfer activation of the Co-C homolysis in adenosylcobalamin-dependent enzyme reactions is considered unlikely, based on four lines of evidence.

Structural and functional analysis of the murine adenosine deaminase gene

We describe the structural and functional analysis of cosmid clones that span the entire murine adenosine deaminase gene. Functional analysis indicated that these clones are capable of encoding murine adenosine deaminase activity when introduced into human cell lines. Structural analysis revealed that the gene consists of 12 exons distributed over approximately 25 kb. The exact size of each exon and the sequence of each exon/intron junction were determined. The results show that the 1056-nucleotide open reading frame for adenosine deaminase extends from exon 1 to exon 11, and that exon 12 contains untranslated sequences only. During the course of these investigations, we discovered that a gene encoding an abundant 1.3-kb polyadenylated transcript overlaps the 3' end of the murine adenosine deaminase gene and is transcribed from the opposite strand.

Identification of transcription stop sites at the 5' and 3' ends of the murine adenosine deaminase gene

We report here the identification and nucleotide sequence of two transcription termination regions associated with the murine adenosine deaminase gene. One region is situated within or very near exon one and in mouse fibroblasts accounts for more than a 50-fold drop in the abundance of nascent transcripts. This termination region is believed to be involved in the regulation of adenosine deaminase gene transcription. The other termination region is located approximately 3.5 kilobases beyond the major polyadenylation site and defines the 3' boundary of the adenosine deaminase transcription unit.