Pedicle screw accuracy placed with assistance of machine vision technology in patients with neuromuscular scoliosis

INTRODUCTION

Pedicle screws are the primary method of vertebral fixation in scoliosis surgery, but there are lingering concerns over potential malposition. The rates of pedicle screw malposition in pediatric spine surgery vary from 10% to 21%. Malpositioned screws can lead to potentially catastrophic neurological, vascular, and visceral complications. Pedicle screw positioning in patients with neuromuscular scoliosis is challenging due to a combination of large curves, complex pelvic anatomy, and osteopenia. This study aimed to determine the rate of pedicle screw malposition, associated complications, and subsequent revision from screws placed with the assistance of machine vision navigation technology in patients with neuromuscular scoliosis undergoing posterior instrumentation and fusion.

METHOD

A retrospective analysis of the records of patients with neuromuscular scoliosis who underwent thoracolumbar pedicle screw insertion with the assistance of machine-vision image guidance navigation was performed. Screws were inserted by either a staff surgeon, orthopaedic fellow, or orthopaedic resident. Post-operative ultra-low dose CT scans were used to assess pedicle screw accuracy. The Gertzbein classification was used to grade any pedicle breaches (grade 0, no breach; grade 1, <2 mm; grade 2, 2-4 mm; grade 3, >4 mm). A screw was deemed accurate if no breach was identified (grade 0).

RESULTS

25 patients were included in the analysis, with a mean age of 13.6 years (range 11 to 18 years; 13/25 (52.0%) were female. The average pre-operative supine Cobb angle was 90.0 degrees (48-120 degrees). A total of 687 screws from 25 patients were analyzed (402 thoracic, 241 lumbosacral, 44 S2 alar-iliac (S2AI) screws). Surgical trainees (fellows and orthopaedic residents) inserted 46.6% (320/687) of screws with 98.8% (4/320) accuracy. The overall accuracy of pedicle screw insertion was 98.0% (Grade 0, no breach). All 13 breaches that occurred in the thoracic and lumbar screws were Grade 1. Of the 44 S2AI screws placed, one screw had a Grade 3 breach (2.3%) noted on intra-operative radiographs following rod placement and correction. This screw was subsequently revised. None of the breaches resulted in neuromonitoring changes, vessel, or visceral injuries.

CONCLUSION

Machine vision navigation technology combined with careful free-hand pedicle screw insertion techniques demonstrated high levels of pedicle screw insertion accuracy, even in patients with challenging anatomy.

The impact of public health lockdown measures during the COVID-19 pandemic on the epidemiology of children's orthopedic injuries requiring operative intervention

BACKGROUND

In March 2020, Ontario instituted a lockdown to reduce spread of the SARS-CoV-2 virus. Schools, recreational facilities, and nonessential businesses were closed. Restrictions were eased through 3 distinct stages over a 6-month period (March to September 2020). We aimed to determine the impact of each stage of the COVID-19 public health lockdown on the epidemiology of operative pediatric orthopedic trauma.

METHODS

A retrospective cohort study was performed comparing emergency department (ED) visits for orthopedic injuries and operatively treated orthopedic injuries at a level 1 pediatric trauma centre during each lockdown stage of the pandemic with caseloads during the same date ranges in 2019 (prepandemic). Further analyses were based on patients' demographic characteristics, injury severity, mechanism of injury, and anatomic location of injury.

RESULTS

Compared with the prepandemic period, ED visits decreased by 20% (1356 v. 1698, p < 0.001) and operative cases by 29% (262 v. 371, p < 0.001). There was a significant decrease in the number of operative cases per day in stage 1 of the lockdown (1.3 v. 2.0, p < 0.001) and in stage 2 (1.7 v. 3.0; p < 0.001), but there was no significant difference in stage 3 (2.4 v. 2.2, p = 0.35). A significant reduction in the number of playground injuries was seen in stage 1 (1 v. 62, p < 0.001) and stage 2 (6 v. 35, p < 0.001), and there was an increase in the number of self-propelled transit injuries (31 v. 10, p = 0.002) during stage 1. In stage 3, all patient demographic characteristics and all characteristics of operatively treated injuries resumed their prepandemic distributions.

CONCLUSION

Provincial lockdown measures designed to limit the spread of SARS-CoV-2 significantly altered the volume and demographic characteristics of pediatric orthopedic injuries that required operative management. The findings from this study will serve to inform health system planning for future emergency lockdowns.

Utility of intraoperative neurophysiological monitoring in detecting motor and sensory nerve injuries in pediatric high-grade spondylolisthesis

BACKGROUND CONTEXT

Intraoperative neuromonitoring (IONM) during surgical correction of spinal deformity has been shown to reduce iatrogenic injury in pediatric and adult populations. Although motor-evoked potentials (MEP), somatosensory-evoked potentials (SSEP), and electromyography (EMG) have been shown to be highly sensitive and specific in detecting spinal cord and nerve root injuries, their utility in detecting motor and sensory nerve root injury in pediatric high-grade spondylolisthesis (HGS) remains unknown.

PURPOSE

We aim to assess the diagnostic accuracy and therapeutic impact of unimodal and multimodal IONM in the surgical management of HGS.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Pediatric patients undergoing posterior spinal fusion (PSF) for treatment of HGS.

OUTCOME MEASURES

Data on patient demographics, spinopelvic and spondylolisthesis parameters, and the presence of pre-and postoperative neurological deficits were collected.

METHODS

Intraoperative MEP, SSEP, and EMG alerts were recorded. Alert criteria were defined as a change in amplitude of more than 50% for MEP and/or SSEP, with or without change in latency, and more than 10 seconds of sustained EMG activity. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for each modality and the combination of MEP and SSEP. The 95% confidence intervals (CIs) were calculated using the exact (Clopper-Pearson) method.

RESULTS

Fifty-four pediatric patients with HGS undergoing PSF between 2003 and 2021 in a single tertiary center were included. Seventy-two percent (39/54) of patients were female; the average age of patients was 13.7±2.3 years. The sensitivity of MEP in detecting new postoperative neurologic deficit was 92.3% (95% CI [64.0-99.8]), SSEP 77.8% (95% CI [40.0-97.2]), EMG 69.2% (95% CI [38.6-90.9]), and combination MEP and SSEP 100% (95% CI [73.5-100]). The specificity of MEP was 80.0% (95% CI [64.4-91.0]), SSEP 95.1% (95% CI [83.5-99.4]), EMG 65.9% (95% CI [49.4-79.9]), and combination MEP and SSEP 82.9% (95% CI [67.9-92.9]). The accuracy of SSEP was 92.0% (95% CI [80.8%-97.8%]), and the combination of MEP and SSEP was 86.8% (95% CI [74.7%-94.5%]). Twelve (22.2%) patients had a new motor or sensory deficit diagnosed immediately postoperatively. Nine patients made a full recovery, and 3 had some neurologic deficit on final follow-up.

CONCLUSION

Unimodal IONM using SSEP and MEP alone were accurate in diagnosing sensory and motor nerve root injuries, respectively. The diagnostic accuracy in predicting motor and sensory nerve injuries in pediatric HGS improved further with the use of multimodal IONM (combining MEP and SEP). We recommend the utilization of multimodal IONM in all HGS PSF surgeries.

Use of monopolar cautery in patient with a vagal nerve stimulator during neuromuscular scoliosis surgery

It is a historic and common practice while performing spine surgery on patients with a VNS has been to have the patient's neurologist turn off the VNS generator in the pre-operative anesthetic care unit and to use bipolar rather than monopolar electrocautery. Here we report a case of a 16-year-old male patient with cerebral palsy and refractory epilepsy managed with an implanted VNS who had scoliosis surgery (and subsequent hip surgery) conducted with the use of monopolar cautery. Although VNS manufacturer guidelines suggest that monopolar cautery should be avoided, perioperative care providers should consider its selective use in high-risk instances (with greater risks of morbidity and mortality due to blood loss which outweigh the risk of surgical re-insertion of a VNS) such as cardiac or major orthopedic surgery. Considering the number of patients with VNS devices presenting for major orthopedic surgery is increasing, it is important to have an approach and strategy for perioperative management of VNS devices.

Incidence of secondary interventions after early spica casting for diaphyseal femur fractures in young children

BACKGROUND

Children aged 6 months to 5 years with diaphyseal femur fractures are typically treated with spica casting, as recommended by the American Association of Orthopaedic Surgeons clinical practice guideline. We aimed to determine the incidence of secondary interventions after early spica casting for femur fractures in children aged 6 years or less.

METHODS

This was a retrospective cohort study of patients aged 6 years or less with diaphyseal femur fractures treated with early spica casting at a single Canadian tertiary care, level 1 trauma pediatric centre between January 2005 and May 2015.

RESULTS

A total of 246 patients were included (190 boys [77.2%] and 56 girls [22.8%] with a mean age of 2.28 yr [standard deviation (SD) 1.35 yr]). Nine patients (3.7%) required early secondary interventions (cast wedging in 8 and flexible intramedullary nail fixation in 1). At last follow-up, 51 patients (20.7%) had clinically measurable limb length discrepancy (LLD) (mean 9.4 mm [SD 3-25 mm]), and 1 patient (0.4%) had mild clinical valgus deformity. Older, heavier patients with initial fracture shortening of 20 mm or more had a higher likelihood of developing a clinically measurable LLD. No patient required surgical intervention after fracture union to correct acquired LLD or angular deformity.

CONCLUSION

Early spica casting for diaphyseal femoral fractures in children aged 6 years or younger had a low rate of complications and return to the operating room, Although 21% of patients had a clinically measurable LLD at last follow-up, no patient required secondary intervention after fracture union to correct acquired LLD or angular deformity. These findings have relevance for the Canadian health care system, especially during the COVID-19 pandemic.

Pediatric Musculoskeletal Radiographs: Anatomy and Fractures Prone to Diagnostic Error Among Emergency Physicians

BACKGROUND

Pediatric musculoskeletal (pMSK) radiograph interpretations are common, but the specific radiograph features at risk of incorrect diagnosis are relatively unknown.

OBJECTIVE

We determined the radiograph factors that resulted in diagnostic interpretation challenges for emergency physicians (EPs) reviewing pMSK radiographs.

METHODS

EPs interpreted 1850 pMSK radiographs via a web-based platform and we derived interpretation difficulty scores for each radiograph in 13 body regions using one-parameter item response theory. We compared the difficulty scores by presence or absence of a fracture and, where applicable, by fracture location and morphology; significance was adjusted for multiple comparisons. An expert panel reviewed the 65 most commonly misdiagnosed fracture-negative radiographs to identify imaging features mistaken for fractures.

RESULTS

We included data from 244 EPs, which resulted in 185,653 unique interpretations. For elbow, forearm, wrist, femur, knee, and tibia-fibula radiographs, those without a fracture had higher interpretation difficulty scores relative to those with a fracture; the opposite was true for the hand, pelvis, foot, and ankle radiographs (p < 0.004 for all comparisons). The descriptive review demonstrated that specific normal anatomy, overlapping bones, and external artefact from muscle or skin folds were often mistaken for fractures. There was a significant difference in difficulty score by anatomic locations of the fracture in the elbow, pelvis, and ankle (p < 0.004 for all comparisons). Ankle and elbow growth plate, fibular avulsion, and humerus condylar fractures were more difficult to diagnose than other fracture patterns (p < 0.004 for all comparisons).

CONCLUSIONS

We identified actionable learning opportunities in pMSK radiograph interpretation for EPs.

A Target Population Derived Method for Developing a Competency Standard in Radiograph Interpretation

CONSTRUCT

For assessing the skill of visual diagnosis such as radiograph interpretation, competency standards are often developed in an ad hoc method, with a poorly delineated connection to the target clinical population.

BACKGROUND

Commonly used methods to assess for competency in radiograph interpretation are subjective and potentially biased due to a small sample size of cases, subjective evaluations, or include an expert-generated case-mix versus a representative sample from the clinical field. Further, while digital platforms are available to assess radiograph interpretation skill against an objective standard, they have not adopted a data-driven competency standard which informs educators and the public that a physician has achieved adequate mastery to enter practice where they will be making high-stakes clinical decisions.

APPROACH

Operating on a purposeful sample of radiographs drawn from the clinical domain, we adapted the Ebel Method, an established standard setting method, to ascertain a defensible, clinically relevant mastery learning competency standard for the skill of radiograph interpretation as a model for deriving competency thresholds in visual diagnosis. Using a previously established digital platform, emergency physicians interpreted pediatric musculoskeletal extremity radiographs. Using one-parameter item response theory, these data were used to categorize radiographs by interpretation difficulty terciles (i.e. easy, intermediate, hard). A panel of emergency physicians, orthopedic surgeons, and plastic surgeons rated each radiograph with respect to clinical significance (low, medium, high). These data were then used to create a three-by-three matrix where radiographic diagnoses were categorized by interpretation difficulty and significance. Subsequently, a multidisciplinary panel that included medical and parent stakeholders determined acceptable accuracy for each of the nine cells. An overall competency standard was derived from the weighted sum. Finally, to examine consequences of implementing this standard, we reported on the types of diagnostic errors that may occur by adhering to the derived competency standard.

FINDINGS

To determine radiograph interpretation difficulty scores, 244 emergency physicians interpreted 1,835 pediatric musculoskeletal extremity radiographs. Analyses of these data demonstrated that the median interpretation difficulty rating of the radiographs was -1.8 logits (IQR -4.1, 3.2), with a significant difference of difficulty across body regions (p < 0.0001). Physician review classified the radiographs as 1,055 (57.8%) as low, 424 (23.1%) medium or 356 (19.1%) high clinical significance. The multidisciplinary panel suggested a range of acceptable scores between cells in the three-by-three table of 76% to 95% and the sum of equal-weighted scores resulted in an overall performance-based competency score of 85.5% accuracy. Of the 14.5% diagnostic interpretation errors that may occur at the bedside if this competency standard were implemented, 9.8% would be in radiographs of low-clinical significance, while 2.5% and 2.3% would be in radiographs of medium or high clinical significance, respectively.

CONCLUSION(S)

This study's novel integration of radiograph selection and a standard setting method could be used to empirically drive evidence-based competency standard for radiograph interpretation and can serve as a model for deriving competency thresholds for clinical tasks emphasizing visual diagnosis.

Fifth metatarsal fractures in skeletally immature patients do not need routine orthopedic surgeon assessment and follow-up

Objectives

The aim of this study was to determine the rate of delayed or nonunion of fifth metatarsal fractures in skeletally immature patients. Using this information, we sought to develop an evidence-based clinical care pathway in order to mitigate unnecessary patient radiation exposure, costs to families, and costs to the health system.

Methods

We retrospectively reviewed the charts and radiographs of patients who presented to an academic tertiary-care paediatric hospital between 2009 and 2014 with isolated fifth metatarsal fractures.

Results

A total of 114 patients (61 males and 53 females) with mean age of 11.2 (SD 3.0) years old were included in the study. No patients required operative management. There was one case of delayed union and no cases of nonunion. There was no association of these complications with fracture type, location, or mechanism of injury. There was no association of complications with immobilization type or immobilization period. Despite the low complication rate and need for surgery, fracture clinic resource utilization was significant. Fractures were managed with a mean number of 3.1 (SD 0.89) clinic visits and a mean number of 2.7 (SD1.0) radiology department visits where a mean total of 7.9 (SD 3.4) x-rays were performed.

Conclusions

Based on our retrospective review, skeletally immature patients presenting with isolated fifth metatarsal fractures have a very low rate of delayed or nonunion. A selective follow-up strategy will decrease radiation exposure, reduce costs to families and the healthcare system, without compromising clinical outcomes.

Factors affecting management of children's low-risk distal radius fractures in the emergency department: a population-based retrospective cohort study

BACKGROUND

Ten randomized controlled trials over the last 2 decades support treating low-risk pediatric distal radius fractures with removable immobilization and without physician follow-up. We aimed to determine the proportion of these fractures being treated without physician follow-up and to determine whether different hospital and physician types are treating these injuries differently.

METHODS

We conducted a retrospective population-based cohort study using ICES data. We included children aged 2-14 years (2-12 yr for girls and 2-14 yr for boys) with distal radius fractures having had no reduction or operation within a 6-week period, and who received treatment in Ontario emergency departments from 2003 to 2015. Proportions of patients receiving orthopedic, primary care and no follow-up were determined. Multivariable log-binomial regression was used to quantify associations between hospital and physician type and management.

RESULTS

We analyzed 70 801 fractures. A total of 20.8% (n = 14 742) fractures were treated without physician follow-up, with the proportion of physician follow-up consistent across all years of the study. Treatment in a small hospital emergency department (risk ratio [RR] 1.86, 95% confidence interval [CI] 1.72-2.01), treatment by a pediatrician (RR 1.22, 95% CI 1.11-1.34) or treatment by a subspecialty pediatric emergency medicine-trained physician (RR 1.73, 95% CI 1.56-1.92) were most likely to result in no follow-up.

INTERPRETATION

While small hospital emergency departments, pediatricians and pediatric emergency medicine specialists were most likely to manage low-risk distal radius fractures without follow-up, the majority of these fractures in Ontario were not managed according to the latest research evidence. Canadian guidelines are required to improve care of these fractures and to reduce the substantial overutilization of physician resources we observed.

Tibial tuberosity ossification predicts reoperation for growth disturbance in distal femoral physeal fractures

PURPOSE

Distal femoral physeal fractures (DFPF) can cause growth disturbance that requires further surgical intervention. The aim of this study is to determine if Tibial Tuberosity Ossification Stage (TTOS) at the time of injury predicts secondary surgery for growth disturbance in patients who have sustained a DFPF.

METHODS

We retrospectively investigated all patients who had operative treatment for a DFPF at a single centre over a 17-year period. Regression analysis was performed investigating associations between secondary surgery to treat growth disturbance and TTOS, age, Salter-Harris fracture classification type, mode of fixation or mechanism of injury.

RESULTS

In all, 85 consecutive patients were identified. A total of 74 met the inclusion criteria. The mean age at time of injury was 13.1 years (2.0 to 17.1). Following fixation, 30 patients (41%) underwent further surgery to treat growth disturbance. Absence of tibial tuberosity fusion to the metaphysis was significantly associated with the need for further surgery (p < 0.001). Odds of requiring secondary surgery after tibial tuberosity fusion to metaphysis (compared with not fused) were 0.12 (95% confidence interval (CI) 0.04 to 0.34). The estimate of the effect of TTOS on reoperation rates did not vary when adjusted for gender, mechanism, fixation and Salter-Harris type. When accounting for age, the odds of any further operation if the tibial tuberosity is fused to the metaphysis (compared with not fused) were 0.28 (95% CI 0.08 to 0.94).

CONCLUSION

TTOS at the time of injury is a predictor of further surgery to treat growth disturbance in paediatric distal femoral fractures.

LEVEL OF EVIDENCE

Diagnostic Level II.

Adverse Events from Emergency Physician Pediatric Extremity Radiograph Interpretations: A Prospective Cohort Study

OBJECTIVES

We determined how often emergency physician pediatric musculoskeletal (MSK) radiograph interpretations were discordant to that of a radiologist and led to an adverse event (AE). We also established the variables independently associated with this outcome.

METHODS

This prospective cohort study was conducted in an urban, tertiary care children's emergency department (ED). We enrolled children who presented to an ED with an extremity injury and received radiographs. ED physicians documented their radiograph interpretation, which was compared to a radiology reference standard. Patients received telephone follow-up and had institutional medical records reviewed in 3 weeks. An AE occurred if there were clinical sequelae and/or repeat health care visits due to a delay in correct radiograph interpretation.

RESULTS

We enrolled 2,302 children (mean [±SD] age = 9.0 [4.4] years; 1,288 (56.0%) male]. Of these, 180 (7.8%; 95% confidence interval = 6.8 to 9.0) ED physician discordant interpretations resulted in an AE. Specifically, there were no negative clinical outcomes; however, relative to cases diagnosed correctly at the index ED, patients whose fracture was not initially identified encountered 77.2% more subsequent ED visits, while those falsely diagnosed with a fracture experienced 41.5% additional orthopedic clinic visits. Odds of an ED discrepant interpretation was significantly higher if a physician's pretest probability of a fracture was ≤ 20% versus> 20% (adjusted odds ratio [aOR] = 1.6), patient's pain score was ≤ 2 versus> 2 (aOR = 1.6), and injury was located in a joint versus other location (aOR = 1.7).

CONCLUSIONS

Emergency physician discordant pediatric MSK radiograph interpretations that resulted in an AE occurred with regular frequency in a pediatric ED setting. AEs were primarily an increase in subsequent health care visits. Importantly, a low clinical suspicion for a fracture or injury located in the joint were risk factors for ED physician discordant interpretations.

Training surgeons and the informed consent discussion in paediatric patients: a qualitative study examining trainee participation disclosure

Background

The process of obtaining informed consent is an important and complex pursuit, especially within a paediatric setting. Medical governing bodies have stated that the role of the trainee surgeon must be explained to patients and their families during the consent process. Despite this, attitudes and practices of surgeons and their trainees regarding disclosure of the trainee’s participation during the consent process has not been reported in the paediatric setting.

Methods

Nineteen face-to-face interviews were conducted with surgical trainees and staff surgeons at a tertiary-level paediatric hospital in Toronto, Canada. These were transcribed and subsequently thematically coded by three reviewers.

Results

Five main themes were identified from the interviews. (1) Surgeons do not consistently disclose the role of surgical trainees to parents. (2) Surgical trainees are purposefully vague in disclosing their role during the consent discussion without being misleading. (3) Surgeons and surgical trainees believe parents do not fully understand the specific role of surgical trainees. (4) Graduated responsibility is an important aspect of training surgeons. (5) Surgeons feel a responsibility towards both their patients and their trainees. Surgeons do not explicitly inform patients about trainees, believing there is a lack of understanding of the training process. Trainees believe families likely underestimate their role and keep information purposely vague to reduce anxiety.

Conclusion

The majority of surgeons and surgical trainees do not voluntarily disclose the degree of trainee participation in surgery during the informed consent discussion with parents. An open and honest discussion should occur, allowing for parents to make an informed decision regarding their child’s care. Further patient education regarding trainees’ roles would help develop a more thorough and patient-centred informed consent process.

Lateral condylar fractures of the humerus in children: does the type of fixation matter?

Aims

Displaced fractures of the lateral condyle of the humerus are frequently managed surgically with the aim of avoiding nonunion, malunion, disturbances of growth and later arthritis. The ideal method of fixation is however not known, and treatment varies between surgeons and hospitals. The aim of this study was to compare the outcome of two well-established forms of surgical treatment, Kirschner wire (K-wire) and screw fixation.

Patients and Methods

A retrospective cohort study of children who underwent surgical treatment for a fracture of the lateral condyle of the humerus between January 2005 and December 2014 at two centres was undertaken. Pre, intraoperative and postoperative characteristics were evaluated. A total of 336 children were included in the study. Their mean age at the time of injury was 5.8 years (0 to 15) with a male:female patient ratio of 3:2. A total of 243 (72%) had a Milch II fracture and the fracture was displaced by > 2 mm in 228 (68%). In all, 235 patients underwent K-wire fixation and 101 had screw fixation.

Results

There was a higher rate of nonunion with K-wire fixation (p = 0.02). There was no difference in Baumann's angle, carrying angle or the rate of major complications between the two groups. No benefit was obtained by immobilizing the elbow for more than four weeks in either group. No short-term complications were seen when fixation crossed the lateral ossific nucleus.

Conclusion

Fixation of lateral condylar humeral fractures in children using either K-wires or screws gives satisfactory results. Proponents of both techniques may find justification of their methods in our data, but prospective, randomized trials with long-term follow-up are required to confirm the findings, which suggest a higher rate of nonunion with K-wire fixation. Cite this article: Bone Joint J 2018;100-B:387-95.

Proximal femoral osteotomy in children with cerebral palsy: the perspective of the trainee

BACKGROUND

There are a range of implants for fixation of proximal femoral osteotomies (PFOs) in children. We investigated the training experiences and preferences of orthopaedic residents and fellows who were learning PFO, using a fixed angled blade plate (ABP) or a locking, cannulated blade plate (LCBP). We also studied short-term technical and radiographic outcomes.

METHODS

This was a prospective, parallel-group, cohort study of 90 consecutive children and adolescents with cerebral palsy who underwent bilateral PFOs with ABP or LCBP. Surgical trainees completed a questionnaire to document the ease or difficulty of each operative step.

RESULTS

There were 48 boys and 42 girls, with a mean age of eight years and a mean follow-up of 25 months. Trainees preferred the LCBP system for: insertion of the guidewire, the seating chisel and the blade plate, as well as overall technical ease of use (p < 0.001). Radiographic outcomes were similar with no between-group differences for migration percentage (p = 0.996) or neck shaft angle (p = 0.849), but there was a higher prevalence of technical errors in the ABP group.

CONCLUSIONS

Trainee surgeons expressed a preference for LCBPs when learning PFO in children with cerebral palsy. Radiographic outcomes were similar in both groups, with close attending surgeon supervision.

Cannulated, locking blade plates for proximal femoral osteotomy in children and adolescents

BACKGROUND

Proximal femoral osteotomy is the most common major reconstructive surgery in the region of the hip joint in children and adolescents. Given that it may be required across a wide range of ages and indications, appropriate instrumentation is necessary to ensure a technically satisfactory result. Recent developments in fixation include cannulation of the blade plate and locking screw technology.

METHODS

We conducted a prospective audit of our first 25 patients who had a unilateral or bilateral proximal femoral osteotomy using a recently available system which combines cannulation and locking plate technology. The principal outcome measures were the radiographic position of the osteotomy at the time of union and surgical adverse events.

RESULTS

Forty-five proximal femoral osteotomies were performed in 25 patients, mean age 8 years (range 3-17 years), for a variety of indications, the most common of which was hip subluxation in children with cerebral palsy. All osteotomies were soundly united by 6 weeks in children and by 3 months in adolescents, in the position achieved intra-operatively. There were no revision procedures and the technical goals of surgery were achieved in all patients. There was one adverse event, a low-grade peri-prosthetic infection, diagnosed at the time of implant removal.

CONCLUSIONS

In this prospective audit of our first 25 patients, the new system performed well across a wide range of ages, body weights and surgical indications. Further comparative studies will be required to determine whether it offers additional advantages over more traditional systems.

Authorship proliferation in the orthopaedic literature

BACKGROUND

Authorship is the currency of the academic orthopaedic surgeon. There has been an unprecedented increase in the number of authors per publication in many biomedical fields. Possible reasons for this trend include increased complexity of research, "undeserved" authorship, and the "pressure to publish." We explored the change in authorship in two leading orthopaedic journals over a period of sixty years.

METHODS

We examined all original research articles and case reports published in The Journal of Bone and Joint Surgery (American and British Volumes) (JBJS-A and JBJS-B) in ten-year intervals from 1949 to 2009. For each article, we determined the number of authors, the geographic origin of the research, and the academic degrees of the authors; we also examined the changes that occurred in these categories.

RESULTS

The mean number of authors per original research article increased from 1.6 in 1949 to 5.1 in 2009. There has been a noticeable internationalization of the two journals, with a decreasing proportion of articles from North America and the United Kingdom and Ireland as a result of increased contributions from Europe and the Far East. Authors with advanced research degrees (PhD; MS; MD, PhD; and MD, MS) account for an increasing proportion of contributing authors; over 30% of authors had an advanced research degree in 2009.

CONCLUSIONS

Our findings suggest that the trend of authorship proliferation in biomedical research is also seen in the orthopaedic literature. The mean number of authors, the proportion of authors per research article with an advanced research degree, and variation in the geographic origin of articles has increased over the past sixty years.

Impaired Pavlovian fear extinction is a common phenotype across genetic lineages of the 129 inbred mouse strain

Fear extinction is impaired in psychiatric disorders such as post-traumatic stress disorder and schizophrenia, which have a major genetic component. However, the genetic factors underlying individual variability in fear extinction remain to be determined. By comparing a panel of inbred mouse strains, we recently identified a strain, 129S1/SvImJ (129S1), that exhibits a profound and selective deficit in Pavlovian fear extinction, and associated abnormalities in functional activation of a key prefrontal-amygdala circuit, as compared with C57BL/6J. The first aim of the present study was to assess fear extinction across multiple 129 substrains representing the strain's four different genetic lineages (parental, steel, teratoma and contaminated). Results showed that 129P1/ReJ, 129P3/J, 129T2/SvEmsJ and 129X1/SvJ exhibited poor fear extinction, relative to C57BL/6J, while 129S1 showed evidence of fear incubation. On the basis of these results, the second aim was to further characterize the nature and specificity of the extinction phenotype in 129S1, as an exemplar of the 129 substrains. Results showed that the extinction deficit in 129S1 was neither the result of a failure to habituate to a sensitized fear response nor an artifact of a fear response to (unconditioned) tone per se. A stronger conditioning protocol (i.e. five x higher intensity shocks) produced an increase in fear expression in 129S1, relative to C57BL/6J, due to rapid rise in freezing during tone presentation. Taken together, these data show that impaired fear extinction is a phenotypic feature common across 129 substrains, and provide preliminary evidence that impaired fear extinction in 129S1 may reflect a pro-fear incubation-like process.

Nitric oxide breath testing by tunable-diode laser absorption spectroscopy: application in monitoring respiratory inflammation

We used a high-resolution mid-IR tunable-laser absorption spectroscopy (TLAS) system with a single IV-VI laser operating near 5.2 microm to measure the level of exhaled nitric oxide (eNO) in human breath. A method of internal calibration using simultaneous eNO and exhaled CO2 measurements eliminated the need for system calibration with gas standards. The results observed from internally calibrating the instrument for eNO measurements were compared with measurements of eNO calibrated to gas standards and were found to be similar. Various parameters of the TLAS system for eNO breath testing were examined and include gas cell pressure, exhalation time, and ambient NO concentrations. A reduction in eNO from elevated concentrations (approximately 44 parts in 10(9)) to near-normal levels (<20 parts in 10(9)) from an asthmatic patient was observed after the patient had received treatment with an inhaled glucocorticoid anti-inflammatory medication. Such measurements can help in evaluating airway inflammation and in monitoring the effectiveness of anti-inflammatory therapies.

Synthesis and characterization of fluorinated and iodinated pyrrolopyrimidines as PET/SPECT ligands for the CRF1 receptor

Fluorine-18 labeled fluorobutyl[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo [2,3-d] pyrimidin-4-yl]ethylamine (FBPPA) and iodine-123 labeled butyl[2,5-dimethyl-7-(4-iodo-2,6-dimethylphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]ethyl-amine (IBPPA) were synthesized in the development of a CRF receptor ligand. The methods of synthesis, in vitro binding assays, radiolabeling and in vivo tissue distribution in rats are described. Fluorine-18 labeled FBPPA was prepared with high specific activity (3 x 10(4) Ci/mmol) by nucleophilic displacement with an average radiochemical yield of 6% (EOB). Iodine-123 labeled IBPPA was prepared by electrophilic iododestannylation with good yield (60%) and high specific activity (3.3 x 10(3) Ci/mmol). The retention of FBPPA and IBPPA in the pituitary was good (1.16% i.d./g and 2.35% i.d./g respectively at 60 min). However, the accumulation of radioactivity in the brain for both radiotracers was very low at all time points of the study, which demonstrated the difficulties for these radiopharmaceuticals to penetrate the blood brain barrier (BBB).

Helicoverpa armigera granulovirus interference with progression of H. zea nucleopolyhedrovirus disease in H. zea larvae

Capsular proteins from Helicoverpa armigera granulovirus (HaGV) have previously been shown to enhance H. armigera nucleopolyhedrovirus (HaSNPV) infection in H. armigera larvae. Yet, HaGV and HaS-NPV, as viable viruses, interfered with one another. In our study, we have examined the effects of co-infection of the slow-killing virus HaGV with the fast-killing virus Helicoverpa zea NPV (HzSNPV) on H. zea larvae. The mortality parameter measured was survival time. Virus stocks had 50% lethal concentrations of 3.2x10(-9) g HaGV-infected cadavers (GVC) (HaGV) and 32 occlusion bodies (HzSNPV) per cup. Average survival times were 16.8 and 5.5 days for larvae treated with HaGV and HzSNPV, respectively; death of HzSNPV-treated larvae was as early as 72 h posttreatment. In co-infection experiments in which larvae were treated concurrently with both viruses, the viruses competed in typical fashion for host resources. However, interference with disease progression in HzSNPV-fed larvae occurred even when HaGV was fed to larvae up to 36 h after the NPV, a time at which NPV infection should have been well established in host larvae. At death, co-infected larvae were observed microscopically to be filled with HaGV granules rather than HzSNPV polyhedra. The time study results imply that HaGV might be outcompeting HzSNPV by inhibiting its replication. We also observed that H. zea larvae treated with high dosages of HaGV (> or =3x10(-5) g GVC) were initially stunted but had survival times similar to those of larvae treated with lower dosages.

Telemedical evaluation of ocular adnexa and anterior segment

PURPOSE

To report the accuracy of telemedical slit-lamp evaluation in examination of ocular adnexa and anterior segment.

METHODS

By means of contingency tables, slit-lamp findings by live examination and by real-time telemedicine were compared in 50 eyes of 25 patients.

RESULTS

Sensitivity percentages (proportion with findings correctly identified by telemedicine)/specificity percentages (proportion without the finding that was correctly identified by telemedicine) were 100/64 for eyelid mass, 100/85 for conjunctival pigment, 100/100 for posterior synechiae, 80/0 for blepharitis, 83/93 for iridotomy, 70/93 for pinguecula, 75/93 for iris lesions, 56/98 for corneal scar, 0/100 for chamber inflammation, 57/93 for nuclear cataract, and 37/100 for intraocular lens presence.

CONCLUSIONS

By means of monocular slit-lamp telemedical evaluation, clinical findings with high contrast cues for color and depth have the highest sensitivity and specificity.

The value of preoperative mammograms in nononcologic breast surgery

It remains unclear whether preoperative mammograms are necessary in young patients having nononcologic breast surgery. Various authors have recommended mammography in all such cases, in conflict with guidelines from the American Cancer Society. We conducted a retrospective study to determine the utility of preoperative mammograms in young women. From 1989 through 1994, 208 patients under 35 years of age had elective breast surgery in our institution. Fifty-one (24.5%) had preoperative mammography. No malignancies were diagnosed. We believe mammograms are not routinely needed before elective breast surgery in patients under 35 years of age.

Temperature Ranges, Growth Optima, and Growth Rates of Spiroplasma (Spiroplasmataceae, class Mollicutes) Species

A new method was developed for determination of the doubling times of spiroplasmas. In this procedure, the time required for medium acidification of tubes in tenfold dilution series was recorded. Sixty-four spiroplasma strains, representing 24 groups and 11 subgroups, were studied. Eight strains representing putative new groups were also included in the study. Doubling times at 5, 10, 15, 20, 25, 30, 32, 37, 41, and 43&deg;C were determined. The range of temperatures for spiroplasma growth was 5&deg;-41&deg;C. Twenty-three spiroplasmas had optima of 30&deg;C, 29 had optima of 32&deg;C, and 13 had optima of 37&deg;C. The fastest growing spiroplasma was the MQ-4 strain (group XI), with a doubling time at optimal temperature of 0.6 h. The slowest was the Jamaican corn stunt strain B655 (subgroup I-3), with an optimal doubling time of 36.7 h. Spiroplasma strain B31 (group IV) had the widest range (5&deg;-41&deg;C), while the DW-1 strain and some subgroup I-3 strains had the narrowest, growing only at 25&deg; and 30&deg;C. Some spiroplasmas grew well at 41&deg;C, but none grew at 43&deg;C. The ability of spiroplasmas to withstand a wide range of temperatures may reflect the conditions to which they are exposed in nature, including the temperatures of the insect, tick, and/or plant hosts in which they are carried and the plant surfaces from which they may be acquired by arthropods.

Development of a measure of medical faculty attitudes toward clinical evaluation of students

PURPOSE

This research involved the development, and in particular the evaluation of the reliability, of scales to measure medical faculty attitudes toward clinical evaluation (ACE) of medical students. The intent was to create measures that yield reliable data and have practical utility in medical education research and faculty development.

METHOD

A systematic, eight-step scale development protocol was used to create the instrument. In early 1993 factor analysis was used on data from 217 clinical faculty at four medical schools to refine the measures. Internal consistency and test-retest reliability analyses were performed. Analyses were also done to determine whether the attitude scores were influenced by such faculty demographic attributes as employing medical school, gender, age, tenure track status, academic rank, or academic department.

RESULTS

An initial pool of 52 items was reduced to 30 items based on iterative reliability studies. Factor analysis on the 30 items yielded two scales: (1) Quality of Evaluation Procedures, 12 items, alpha = .81; and (2) Content of Departmental Evaluations, eight items, alpha = .85. Test-retest reliabilities (12 weeks) for the scales were .67 and .74, respectively. Faculty demographics did not influence attitudes about the quality of evaluation procedures. However, family physicians showed a slightly more positive attitude toward the content of departmental evaluations than did physicians in five other medical specialties.

CONCLUSION

The goal of developing reliable measures of faculty attitudes toward clinical evaluation of medical students has been achieved. With baseline reliabilities established, future research should assess the validity and utility of the scales, especially in the context of clinical practice examinations.

Treatment of tyramine-induced brain edema with anion transport inhibitor L-644,711

Tyramine induces coma in phenelzine-treated dogs. Development of coma in these animals is associated with brain edema, abnormal brain scans of Tc-99m-diethylene-triamine-penta-acetic acid (Tc-99m-DTPA), and elevated levels of CSF catecholamines. We found that the intravenous administration of 6-7 mg/kg of a single dose of L-644,711 given fifteen minutes after the oral administration of tyramine to phenelzine-pretreated animals followed by an infusion of normal saline containing 6-7 mg/kg of the drug given over a period of 2 hr caused reversal of brain injury. This was accompanied by full recovery within a period of 24 hr of all the animals tested. A follow-up study revealed that 24 hr after treatment with L-644,711 CSF levels of catecholamines and brain images of Tc-99m-DTPA were indistinguishable from normal controls. Animals that received no drug died from unresolved coma within 4 to 24 hr. Animals that had recovered due to therapy with L-644,711 were given 10-14 days rest followed by a repetition of the phenelzine and tyramine treatment but denied L-644,711 therapy. These animals also died of unresolved coma within 24 hr. This preliminary study suggest that the use of L-644,711 may constitute an important advance in treatment of brain edema of a wide range of neurological disorders.

Bronchiolitis obliterans and Nocardia asteroides infection of the lung

This report describes a patient with right lower lung (RLL) pneumonia of a subacute nature. Sputum and bronchial washings both grew N asteroides. Open lung biopsy showed bronchiolitis obliterans. Both the clinical and radiologic picture dramatically improved during three weeks of treatment with trimethoprim and sulfamethoxazole (TMP - SMX), indicating the possibility that N asteroides infection contributed to bronchiolitis obliterans pneumonia in this patient.

Comparison of virulence factors and antibiotic resistance profiles of Escherichia coli strains from humans and dogs with urinary tract infections

The purpose of this study was to compare virulence factors and antibiotic resistance profiles of Escherichia coli strains isolated from dogs and humans with urinary tract infections. Factors studied included resistance to antibiotics and the transferability of R-plasmids to a recipient E. coli; production of colicins, hemolysins, beta-lactamase, and urease; hemagglutination of erythrocytes; and fermentation of dulcitol. The canine E. coli isolates had a wider range of antibiotic resistance and a higher R-plasmid transmissibility rate. A higher percentage of the canine isolates produced colicins (40% vs. 24%), hemolysins (44% vs. 16%), beta-lactamase (52% vs. 4%), and fermented dulcitol (84% vs. 80%) as compared with the human isolates. The human isolates had a greater ability to hemagglutinate erythrocytes as compared with the canine isolates (24% vs. 8%). None of the isolates produced urease.