Publications by authors named "Patrick Bosch"

33 Publications

Acetabular Coverage Decreases at the End of Skeletal Growth: A 3DCT Study of Healthy Hips.

J Pediatr Orthop 2021 Mar;41(3):e232-e239

Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA.

Background: Abnormalities in size and position of the acetabulum have been linked to both developmental dysplasia of the hip and femoroacetabular impingement. Owing to its 3-dimensional (3D) complexity, plain radiography and cross-sectional studies [computed tomography (CT) and magnetic resonance imaging] have limitations in their ability to capture the complexity of the acetabular 3D anatomy. The goal of the study was to use 3D computed tomography reconstructions to identify the acetabular lunate cartilage and measure its size at varying ages of development and between sexes.

Methods: Patients aged 10 to 18 years with asymptomatic hips and a CT pelvis for appendicitis were reviewed. Patients were stratified by sex and age: preadolescent (10 to 12), young adolescent (13 to 15), and old adolescent (16 to 18) in equal proportions. Materialise 3-matic was used to generate a 3D pelvic model, and the acetabular lunate cartilage surface area was calculated. The lunate cartilage was divided into anatomic segments: superior (11:00 to 1:00), anterior (1:00 to 4:00), and posterior (8:00 to 11:00). The femoral head surface area was calculated to control for patient size. Mixed effects models were generated predicting segment size where side was treated as a repeated measure. Absolute and relative (lunate cartilage to femoral head) models were generated.

Results: Sixty-two patients (124 hips) were included. Females showed a significant decrease in femoral head coverage as age increased overall and in the 3 subsegments. The majority of changes occurred between the preadolescent and young adolescent groups. Males did not show an overall change, but the superior and anterior anatomic subgroups showed a significant decrease in coverage between the young and old adolescent groups. Male lunate cartilages were absolutely, but not relatively, larger than females. No clinically significant side-to-side differences were noted.

Conclusions: The relative femoral head coverage by the acetabular lunate cartilage reduced with increasing age, suggesting the growth of the femoral head outpaces the acetabular lunate cartilage's growth. This was more prominent in females. This study has important implications for expected acetabular coverage changes in the latter aspects of pediatric and adolescent development.

Level Of Evidence: Level III-diagnostic study.
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March 2021

Epiphyseal Translation as a Predictor of Avascular Necrosis in Unstable Slipped Capital Femoral Epiphysis.

J Pediatr Orthop 2021 Jan;41(1):40-45

Departments of Orthopaedic Surgery.

Background: Physeal instability has been shown to be associated with a higher risk of avascular necrosis (AVN) in patients with slipped capital femoral epiphysis (SCFE). The purpose of this study was to identify additional preoperative factors associated with AVN in patients with unstable SCFE.

Methods: Basic demographic information, chronicity of symptoms, and estimated duration of nonambulatory status were noted. Preoperative radiographs were used to measure the Southwick slip angle, slip severity by Wilson criteria, and epiphyseal translation. Translation was measured by 3 distinct radiographic parameters in the position demonstrating maximal displacement. Postoperative radiographs at the time of most recent follow-up were assessed for the presence of AVN. Translation measurements were tested for inter-rater reliability. Patients who developed AVN were compared with those that did not by Fisher exact test and Wilcoxon tests. Logistic regression assessed the effect of translation on the odds of developing AVN. Receiver operating characteristic curve was plotted to assess any threshold effect.

Results: Fifty-one patients (55 hips) out of 310 patients (16%) treated for SCFE were considered unstable. Seventeen hips' unstable SCFE (31%) showed radiographic evidence of AVN. Slip severity by Wilson grade (P=0.009) and epiphyseal translation by all measurements (P< 0.05) were statistically significantly greater among patients who developed AVN. Superior translation had the best inter-rater reliability (intraclass correlation coefficient=0.84). Average superior translation in hips that developed AVN was 17.2 mm compared with 12.9 mm in those that did not (P<0.02). Although the receiver operating characteristic curve did not demonstrate a threshold effect for AVN, it did effectively rule out AVN in cases with <1 cm of superior translation. Age, sex, laterality, chronicity of prodromal symptoms or inability to bear weight, Southwick slip angle, and method of treatment did not vary with the occurrence of AVN.

Conclusions: Epiphyseal translation, either by Wilson Grade or measured directly, is associated with AVN in patients with an unstable SCFE.

Level Of Evidence: Level II-development of diagnostic criteria.
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January 2021

Intermediate-term annualized curve progression of adolescent idiopathic scoliosis curves measuring 40° or greater.

Spine Deform 2020 08 24;8(4):629-636. Epub 2020 Feb 24.

Pediatric Orthopaedic Division, Children's Hospital of Pittsburgh, University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.

Study Design: Prospective cohort study.

Objectives: The objective of this study was to examine intermediate-term progression for a large series of patients with adolescent idiopathic scoliosis (AIS) with curves 40° or greater.

Background: Curve progression in AIS has been well documented for smaller curves in adolescence up to skeletal maturity; however, the data on curve progression past 40° or into adulthood are limited. With many surgeons recommending surgical correction when patients reach this threshold, it is important to understand the radiographic progression of curves into adulthood.

Methods: A database of all patients seen by a single surgeon from 1984 through 2018 with AIS curves progressing to at least 40° entered prospectively was utilized for this study. This included a total of 738 patients. Curve progression was analyzed overall and stratified by length of follow-up, curve location, and Risser stage at the time of presentation among other variables. Curve magnitude and Risser stage designations in this study were validated by performing a separate inter- and intrarater agreement study using four independent reviewers reading 50 patients' Cobb angle and Risser stage blinded in triplicate to examine the reliability of the study measurements.

Results: Annualized curve progression (ACP) averaged 6.3 ± 10.4°. ACP varied with length of follow-up: patients with up to 1 year of follow-up had an average ACP of 11.5 ± 17.0°, while those with 1-2 years had 8.2 ± 8.8°, and 2-5 years had 3.7 ± 4.1°, tapering off further from there. Risser stage 0 or 1 was associated with the highest ACP as compared to Risser stage 2-3 or 4-5. Intraclass correlation (ICC) values for Cobb angle measurement and Risser stage designations from four raters measuring 50 patients' measures, blinded and in triplicate, were all > 0.80, signifying a high degree of reliability within and between readers.

Conclusions: Annualized curve progression for 40° and greater curves was not linear over time; it was greatest immediately after a curve reaches 40° and tapered off over the next decade. Immature Risser stage at presentation was strongly associated with increasing ACP at all time frames.

Level Of Evidence: Prognostic Level I.
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August 2020

Comparison of the Coagulation Profile of Adolescent Idiopathic Scoliosis Patients Undergoing Posterior Spinal Fusion With and Without Tranexamic Acid.

Spine Deform 2019 11;7(6):910-916

Department of Orthopaedic Surgery, University of Pittsburgh Medical Center Children's Hospital of Pittsburgh, 4401 Penn Avenue, Faculty Pavilion, 4th Floor, Pittsburgh, PA 15224, USA.

Study Design: Prospective, observational cohort study.

Objective: To improve the understanding of coagulation and bleeding mechanisms during spinal deformity surgery.

Summary Of Background Data: Fibrinolysis is the mechanism of bleeding for adolescent idiopathic scoliosis undergoing posterior spinal fusion. Antifibrinolytics have become popular; however, literature to support their use remains mixed. The mechanism of action has not been demonstrated.

Methods: The coagulation profile of 88 adolescent idiopathic scoliosis patients undergoing posterior spinal fusion was analyzed. Standard coagulation laboratory investigations and thromboelastograms were drawn hourly through the case. Fifty-eight patients received no antifibrinolytic, whereas 30 patients received tranexamic acid by standardized protocol. The coagulation parameters, estimated blood loss, and transfusion requirements were compared in the two groups.

Results: The two cohorts had no differences in demographic or surgical characteristics. Mean age was 13.6 years, 83% were female, a mean of 11.1 levels were fused, and the mean duration of surgery was 209 minutes. The tranexamic acid cohort did not demonstrate a decrease in blood loss. The transfusion rate, however, dropped from 47% in the non-tranexamic acid cohort to 23% in the tranexamic acid cohort (p = .03). Standard coagulation parameters did not differ between the groups. Fibrinolysis was diminished in the tranexamic acid cohort as measured by a Fibrinolysis score (mean maximum value 2.0 without tranexamic acid vs. 0.7 with tranexamic acid, p < .0001) and the lysis percent at 30 minutes by thromboelastogram (elevated to 3.9% without tranexamic acid vs. 1.2% with tranexamic acid at the 3-hour mark, p = .05).

Conclusions: This study provides confirmation of antifibrinolytic activity during posterior spinal fusion for adolescent idiopathic scoliosis. The presented data of fibrinolysis are proposed as standard measurements for future work on controlling blood loss during scoliosis surgery.

Level Of Evidence: Level 2, prospective comparative study.
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November 2019

Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST): Development and Validation of a Prognostic Model in Untreated Adolescent Idiopathic Scoliosis Using the Simplified Skeletal Maturity System.

Spine Deform 2019 11;7(6):890-898.e4

3851 Katella Avenue, Suite 255, Los Alamitos, CA 90720, USA.

Study Design: Prognostic study and validation using prospective clinical trial data.

Objective: To derive and validate a model predicting curve progression to ≥45° before skeletal maturity in untreated patients with adolescent idiopathic scoliosis (AIS).

Summary Of Background Data: Studies have linked the natural history of AIS with characteristics such as sex, skeletal maturity, curve magnitude, and pattern. The Simplified Skeletal Maturity Scoring System may be of particular prognostic utility for the study of curve progression. The reliability of the system has been addressed; however, its value as a prognostic marker for the outcomes of AIS has not. The BrAIST trial followed a sample of untreated AIS patients from enrollment to skeletal maturity, providing a rare source of prospective data for prognostic modeling.

Methods: The development sample included 115 untreated BrAIST participants. Logistic regression was used to predict curve progression to ≥45° (or surgery) before skeletal maturity. Predictors included the Cobb angle, age, sex, curve type, triradiate cartilage, and skeletal maturity stage (SMS). Internal and external validity was evaluated using jackknifed samples of the BrAIST data set and an independent cohort (n = 152). Indices of discrimination and calibration were estimated. A risk classification was created and the accuracy evaluated via the positive (PPV) and negative predictive values (NPV).

Results: The final model included the SMS, Cobb angle, and curve type. The model demonstrated strong discrimination (c-statistics 0.89-0.91) and calibration in all data sets. The classification system resulted in PPVs of 0.71-0.72 and NPVs of 0.85-0.93.

Conclusions: This study provides the first rigorously validated model predicting a short-term outcome of untreated AIS. The resultant estimates can serve two important functions: 1) setting benchmarks for comparative effectiveness studies and 2) most importantly, providing clinicians and families with individual risk estimates to guide treatment decisions.

Level Of Evidence: Level 1, prognostic.
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November 2019

Erratum to "Why intraperitoneal glucose sensing is sometimes surprisingly rapid and sometimes slow: A hypothesis" [Med. Hypotheses 132 (2019) 109318].

Med Hypotheses 2020 01 14;134:109411. Epub 2019 Oct 14.

Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Endocrinology, St Olav's Hospital, Trondheim, Norway.

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January 2020

Why intraperitoneal glucose sensing is sometimes surprisingly rapid and sometimes slow: A hypothesis.

Med Hypotheses 2019 Nov 20;132:109318. Epub 2019 Jul 20.

Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Endocrinology, St Olav's Hospital, Trondheim, Norway.

The artificial pancreas requires fast and reliable glucose measurements. The peritoneal space has shown promising results, and in one of our studies we detected glucose changes in the peritoneal space already at the same time as in the femoral artery. The peritoneal lining is highly vascularised, covered by a single layer of mesothelial cells and therefore easily accessible for proper sensor technology, e.g. optical technology. We hypothesize that the rapid intraperitoneal glucose dynamics observed in our study was possible because the sensors were located directly at the peritoneal lining, at the point where the glucose molecules entered the peritoneal space. Glucose travels slowly in fluids by diffusion, and a longer distance between the sensor and the peritoneal lining would consequently result in slower dynamics. We therefore propose to place the glucose sensor in an artificial pancreas as closely to the peritoneal lining as possible, or even utilize appropriate sensor technology to measure glucose in the peritoneal lining itself.
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November 2019

Biomechanical Analysis of a Growing Rod with Sliding Pedicle Screw System for Early-Onset Scoliosis.

J Healthc Eng 2019 12;2019:9535070. Epub 2019 Jun 12.

Ferguson Laboratory for Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

Early-onset scoliosis (EOS) remains a challenging condition for which current nonfusion surgeries require iterative lengthening surgeries. A growing rod with sliding pedicle screw system (GRSPSS) was developed to treat spinal deformities without repeated operative lengthening. This study was performed to evaluate whether GRSPSS had similar stability as a conventional pedicle screw system to maintain deformity correction. A serial-linkage robotic manipulator with a six-axis load cell positioned on the end-effector was utilized to evaluate the mechanical stability of the GRSPSS versus conventional fixed scoliosis instrumentation. Ten skeletally mature thoracic female Katahdin sheep spines (T4-L1) were subjected to 2.5 Nm of flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in 2° increments for each state. The overall range of motion (ROM), apical segment ROM, and stiffness were calculated and reported. A two-tailed paired -test was used to detect significant differences ( < 0.05) between the fixed group and GRSPSS fixation. There were no significant differences in overall range of motion (ROM), apical segment ROM, or stiffness for FE or LB between the GRSPSS group and fixed group. In AR, the GRSPSS group showed increased ROM compared to the fixed group for the overall spine (36.0° versus 19.2°, < 0.01) and for the instrumented T8-T10 segments (7.0° versus 2.9°, =0.02). Similarly, the fixed rod elastic zone (EZ) stiffness was significantly greater than the GRSPSS EZ stiffness (0.29 N/m versus 0.17 N/m, < 0.001). The space around the rod allows for the increased AR observed with the GRSPSS fusion technique and is necessary for axial growth. The GRSPSS fusion model shows equivalent flexion and LB stability to current fusion models and represents a stable fusion technique and may allow for longitudinal growth during childhood.
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September 2020

Biomechanical Analysis of Wide Posterior Releases Compared With Inferior Facetectomy and Discectomy in the Thoracolumbar and Lumbar Spine.

Spine Deform 2019 05;7(3):404-409

Department of Orthopaedics, University of Pittsburgh Ferguson Laboratory for Orthopaedic Research, 200 Lothrop St., E1658, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Study Design: In vitro biomechanical analysis.

Objectives: Compare the destabilizing effects of anterior discectomy to posterior spinal releases.

Summary Of Background Data: Posterior release and pedicle screw fixation has become the accepted form of treatment for lumbar and thoracolumbar pediatric scoliotic spinal deformity. A biomechanical evaluation of posterior releases with comparison to traditional anterior releases has not been reported in the lumbar spine.

Methods: Eleven fresh-frozen human thoracolumbar specimens (T9-L5) were tested by a robotic manipulator (Staubli RX90; moment target of 5.0 Nm, force target of 50 N) in axial rotation (AR), plus lateral and anterior translation (LT and AT). Specimens underwent either sequential anterior release (partial and full discectomy) or posterior release (inferior facetectomy and wide posterior release) from T10 to L4. Partial discectomy retained the posterior 50% of disc and posterior longitudinal ligament, whereas full discectomy removed all of the disc and PLL. Wide posterior release included total facetectomy plus ligamentum flavum and spinous process resection.

Results: Inferior facetectomy produced an average increase of 1.5° ± 1.0° (p = .0625), 1.0 ± 0.8 mm (p = .0313), and 0.2 ± 0.3 mm (p = .156) in AR, LT, and AT, respectively. Compared with partial facetectomy, wide posterior release produced an average additional increase of 8.1° ± 4.0° (p = .0312), 2.0 ± 2.2 mm (p = .4062), and 1.1 ± 1.0 mm (p = .0625) in AR, LT, and AT, respectively. Full discectomy produced 201%, 161%, and 153% of the motion relative to wide posterior release in AR, LT, and AT, respectively (p = .0043, .0087, and .0173). Partial discectomy and wide posterior release proved statistically equivalent.

Conclusions: Wide posterior release of the thoracolumbar spine allows significant correction and may be superior to inferior facetectomy in axial rotation. Although complete discectomy with PLL resection would likely allow greater correction, a more clinically realistic partial discectomy confers similar corrective potential in vitro compared with wide posterior release.

Level Of Evidence: Not applicable.
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May 2019

Effect of sensor location on continuous intraperitoneal glucose sensing in an animal model.

PLoS One 2018 9;13(10):e0205447. Epub 2018 Oct 9.

Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.

Background: In diabetes research, the development of the artificial pancreas has been a major topic since continuous glucose monitoring became available in the early 2000's. A prerequisite for an artificial pancreas is fast and reliable glucose sensing. However, subcutaneous continuous glucose monitoring carries the disadvantage of slow dynamics. As an alternative, we explored continuous glucose sensing in the peritoneal space, and investigated potential spatial differences in glucose dynamics within the peritoneal cavity. As a secondary outcome, we compared the glucose dynamics in the peritoneal space to the subcutaneous tissue.

Material And Methods: Eight-hour experiments were conducted on 12 anesthetised non-diabetic pigs. Four commercially available amperometric glucose sensors (FreeStyle Libre, Abbott Diabetes Care Ltd., Witney, UK) were inserted in four different locations of the peritoneal cavity and two sensors were inserted in the subcutaneous tissue. Meals were simulated by intravenous infusions of glucose, and frequent arterial blood and intraperitoneal fluid samples were collected for glucose reference.

Results: No significant differences were discovered in glucose dynamics between the four quadrants of the peritoneal cavity. The intraperitoneal sensors responded faster to the glucose excursions than the subcutaneous sensors, and the time delay was significantly smaller for the intraperitoneal sensors, but we did not find significant results when comparing the other dynamic parameters.
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March 2019

Absent pedicles in campomelic dysplasia.

Childs Nerv Syst 2017 Jun 26;33(6):987-992. Epub 2017 Apr 26.

Neurological Surgery, Bioengineering and Physical Medicine and Rehabilitation, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.

Objectives: The objective of the present study is to report a case of campomelic dysplasia illustrating the absence of cervical and thoracic pedicles. This report reiterates the importance of this clinical peculiarity in the setting of spine instrumentation.

Materials And Methods: A 10-year-old female patient with campomelic dysplasia presented with progressive kyphoscoliosis and signs of neural compromise. Imaging studies confirmed thoracic level stenosis and demonstrated absence of multiple pedicles in cervical and thoracic spine. The patient underwent decompression and instrumentation/fusion for her spinal deformity.

Results: The patient was instrumented between C2 and L4 with pedicle screws and sublaminar cables. However, pedicle fixation was not possible for the lower cervical and upper-mid thoracic spine. Also, floating posterior elements precluded the use of laminar fixation in the lower cervical spine. Cervicothoracic lumbosacral orthosis (CTLSO) was used for external immobilization to supplement the tenuous fixation in the cervicothoracic area. The patient improved neurologically with no signs of implant failure at the 2-year follow-up.

Conclusions: Absence of pedicles and floating posterior elements present a challenge during spine surgery in campomelic dysplasia. Surgeons should prepare for alternative fixation methods and external immobilization when planning on spinal instrumentation in affected patients.

Level Of Evidence: Level IV Case Report.
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June 2017

Outcomes of Pediatric Fractures Managed With Closed Reduction by Orthopaedic Residents in the Emergency Department.

J Pediatr Orthop 2017 Jun;37(4):e243-e245

*Children's Hospital of PittsburghPittsburgh, PA †Kids Specialty Center, Lafayette, LA.

Background: Closed reduction of pediatric fractures is commonly performed by orthopaedic residents using conscious sedation in the emergency department (ED). The purpose of this study was to determine the rate of satisfactory reductions as performed by residents, and to determine the outcomes of these procedures.

Methods: A retrospective review was performed of all fractures that underwent closed reduction under conscious sedation in the ED of a level 1 pediatric trauma center between January 1, 2010 and November 30, 2014. Initial and subsequent radiographs were reviewed and a determination was made as to whether the initial reduction was satisfactory, based on predetermined criteria for angulation and displacement. If a second reduction attempt in the operating room was necessary, this was noted. Chart notes were reviewed until a documented endpoint was reached, such as uneventful healing, malunion, nonunion, or growth arrest.

Results: A total of 838 subjects were identified. The upper extremity was involved in 85% of the fractures. Of the initial 838 fracture reductions performed, 39 (4.7%) were unsatisfactory. Residents on their first pediatric orthopaedic rotation had a higher unsatisfactory reduction rate compared with more experienced residents (7.0% vs. 3.4%, P=0.01). A second reduction was performed for 94 of 749 (12.6%) fractures. Of these, 35 (37.2%) required an open procedure to accomplish a satisfactory reduction. Fractures with initially satisfactory reductions were significantly less likely to require a second reduction attempt than those with initially unsatisfactory reductions (9.2% vs. 80.0%, P<0.01). The likelihood of a satisfactory reduction was significantly higher in the upper extremity than in the lower extremity. Overall, the vast majority (99.2%) of fractures had a satisfactory final outcome.

Conclusions: Most attempts at closed reduction of pediatric fractures in the ED by orthopaedic residents are successful, and the likelihood of a satisfactory reduction was associated with increased levels of resident experience. Fractures with an initially successful reduction were far less likely to require remanipulation.

Level Of Evidence: Level IV-this is a therapeutic case series.
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June 2017

Is There Value in Having Radiology Provide a Second Reading in Pediatric Orthopaedic Clinic?

J Pediatr Orthop 2017 Jun;37(4):e292-e295

*Children's Hospital of Pittsburgh †University of Pittsburgh School of Public Health, Pittsburgh, PA.

Background: The Joint Commission on Accreditation of Healthcare Organizations specifically mandates the dual interpretation of musculoskeletal radiographs by a radiologist in addition to the orthopaedist in all hospital-based orthopaedic clinics. Previous studies have questioned the utility of this practice. The purpose of this study was to further investigate the clinical significance of having the radiologist provide a second interpretation in a hospital-based pediatric orthopaedic clinic.

Methods: A retrospective review was performed of all patients who had plain radiographs obtained in the pediatric orthopaedic clinic at an academic children's hospital over a 4-month period. For each radiographic series, the orthopaedist's note and the radiology interpretation were reviewed and a determination was made of whether the radiology read provided new clinically useful information and/or a new diagnosis, whether it recommended further imaging, or if it missed a diagnosis that was reflected in the orthopaedist's note. The hospital charges associated with the radiology read for each study were also quantified.

Results: The charts of 1570 consecutive clinic patients who were seen in the pediatric orthopaedic clinic from January to April, 2012 were reviewed. There were 2509 radiographic studies performed, of which 2264 had both a documented orthopaedist's note and radiologist's read. The radiologist's interpretation added new, clinically important information in 1.0% (23/2264) of these studies. In 1.7% (38/2264) of the studies, it was determined that the radiologist missed the diagnosis or clinically important information that could affect treatment. The total amount of the professional fees charged for the radiologists' interpretations was $87,362. On average, the hospital charges for each occurrence in which the radiologist's read provided an additional diagnosis or clinically important information beyond the orthopaedist's note were $3798.

Conclusions: The results of this study suggest that eliminating the requirement to have the radiologist interpret radiographs in the pediatric orthopaedic clinic would have few clinical consequences.

Level Of Evidence: Level III-This is a diagnostic retrospective cohort study.
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June 2017

Coagulation Profile of Patients with Adolescent Idiopathic Scoliosis Undergoing Posterior Spinal Fusion.

J Bone Joint Surg Am 2016 Oct;98(20):e88

Department of Anesthesia, Magee-Womens Hospital, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Background: Blood loss and transfusion requirements during posterior spinal fusion for adolescent idiopathic scoliosis remain a concern. The mechanism of bleeding in these patients is poorly characterized. Thromboelastography is a comprehensive test of a patient's coagulation system commonly used in cardiac surgical procedures. It has not been well studied for use in patients with adolescent idiopathic scoliosis.

Methods: A prospective, observational study of the coagulation profile of patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion is presented. Healthy patients with adolescent idiopathic scoliosis without a bleeding abnormality were analyzed during posterior spinal fusion. Standard coagulation laboratory and thromboelastogram measures were obtained at the time of the incision and at 1-hour intervals during the surgical procedure. Laboratory values were analyzed in relation to outcomes such as bleeding, transfusion, and a fibrinolysis score.

Results: Fifty-eight patients were observed. Eighty-one percent of patients were female, the mean age was 13.5 years, a mean of 11.1 levels were fused, the median estimated blood loss was 645 mL, and 47% of patients received blood products. Overall, laboratory values remained stable throughout the surgical procedure. Mild increases in prothrombin time and partial thromboplastin time were observed, and platelets remained stable. From thromboelastogram analysis, an acceleration of clot formation (decreased reaction time) and a slight increase in clot lysis (increased lysis percentage at 30 minutes) were observed. A fibrinolysis score compiled from the presence of fibrin degradation products, the presence of D-dimers, and increased prothrombin time rose steadily over surgical time. The fibrinolysis score was predictive of both transfusion and greater estimated blood loss per level.

Conclusions: The stress of posterior spinal fusion induces a hypercoagulable state in patients with adolescent idiopathic scoliosis. Over the first 2 hours of a surgical procedure, varying degrees of fibrinolysis develop. Platelets and coagulation factors are not depleted. Our data support the use of antifibrinolytic therapy for patients with adolescent idiopathic scoliosis.
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October 2016

Defining the Differences in Transverse Plane Trajectories for Thoracic Pedicle Screw Insertion: Anatomic Versus Medial.

Spine Deform 2016 Jan 23;4(1):22-26. Epub 2015 Dec 23.

Department of Anthropology, University of New Mexico, Albuquerque, MN 87131, USA.

Study Design: Comparing thoracic pedicle screw trajectories, screw lengths, and starting points by examining osteologic specimens.

Objective: Describe a medial screw trajectory (MST) compared to a screw trajectory along the anatomic pedicle angle (APA) in terms of trajectory, screw length, and starting point.

Summary Of Background Data: Although thoracic pedicle screw insertion is commonly used for posterior fusion and instrumentation, there is little data to quantify an MST that avoids the great vessels and allows for greater screw purchase.

Methods: Thirty adult female skeleton thoracic vertebral columns from the University of New Mexico Maxwell Museum of Anthropology Osteology Collection were photographed from axial and right and left lateral views from T1 to T12. Axial plane measurements included APA and MST (both measured from the midline), screw lengths, and APA/MST intersection on the superior articular facet (SAF). The MST was defined as an insertion angle through the midpoint of the pedicle isthmus intersecting the anterior midpoint of the vertebral body. The intersection of each trajectory with the SAF was measured in relation to the lateral base of the SAF, reported as a percentage of the SAF base width from the lateral SAF border.

Results: At every vertebral level, the APA was different from the MST for angle, screw length, and SAF intersection (p < .0001), with the largest difference at T12. The T12 differences were APA versus MST angles (-25.5°, 95% CI -22.7° to -28.4°), screw lengths (11.0 mm, 95% CI 9.2 mm to 12.9 mm), and percentage of SAF width from the lateral border of the SAF base (38.6%, 95% CI 29.1% to 48.1%).

Conclusions: The MST was approximately 8° to 10° greater at T1-T10 (19° at T11 and 25° at T12) than the traditional APA insertion angle. This resulted in a much more lateral starting point on the SAF and longer screw length, greatest at T12.
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January 2016

Does a Weekly Didactic Conference Improve Resident Performance on the Pediatric Domain of the Orthopaedic In-Training Examination?

J Pediatr Orthop 2017 Mar;37(2):149-153

*Shriners Hospitals for Children, Philadelphia †Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh §Department of Orthopaedic Surgery, UPMC Hamot, Erie, PA ‡Department of Orthopaedic Surgery, Cooper Medical School of Rowan University, Camden, NJ.

Background: Performance on the Orthopaedic In-training Examination (OITE) has been correlated with performance on the written portion of the American Board of Orthopaedic Surgery examination. Herein we sought to discover whether adding a regular pediatric didactic lecture improved residents' performance on the OITE's pediatric domain.

Methods: In 2012, a didactic lecture series was started in the University of Pittsburgh Medical Center (UPMC) Hamot Orthopaedic Residency Program (Hamot). This includes all topics in pediatric orthopaedic surgery and has teaching faculty present, and occurs weekly with all residents attending. A neighboring program [UMPC Pittsburgh (Pitt)] shares in these conferences, but only during their pediatric rotation. We sought to determine the effectiveness of the conference by comparing the historic scores from each program on the pediatric domain of the OITE examination to scores after the institution of the conference, and by comparing the 2 programs' scores.

Results: Both programs demonstrated improvement in OITE scores. In 2008, the mean examination score was 19.6±4.3 (11.0 to 30.0), and the mean percentile was 57.7±12.6 (32.0 to 88.0); in 2014, the mean examination score was 23.5±4.2 (14.0 to 33.0) and the mean percentile was 67.1±12.1 (40.0 to 94.0). OITE scores and percentiles improved with post graduate year (P<0.0001). Compared with the preconference years, Hamot residents answered 3.99 more questions correctly (P<0.0001) and Pitt residents answered 2.93 more questions correctly (P<0.0001). Before the conference, site was not a predictor of OITE score (P=0.06) or percentile (P=0.08); there was no significant difference found between the mean scores per program. However, in the postconference years, site did predict OITE scores. Controlling for year in training, Hamot residents scored higher on the OITE (2.3 points higher, P=0.003) and had higher percentiles (0.07 higher, P=0.004) than Pitt residents during the postconference years.

Conclusions: This study suggests that adding a didactic pediatric lecture improved residents' scores on the OITE and indirectly suggests that more frequent attendance is associated with better scores.

Level Of Evidence: Level III-retrospective case-control study.
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March 2017

Subscapular Abscess in a Nine-Year-Old Female Patient: A Case Report.

JBJS Case Connect 2015 Jan-Mar;5(1):e13

Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Kaufmann Medical Building, Suite 911, 3471 Fifth Avenue, Pittsburgh, PA 15213.

Case: The subscapular space is a clinically concealed anatomic space where soft-tissue abscesses can form. To our knowledge, five cases of a subscapular abscess have been reported in the past thirty-four years, so there is little evidence available to guide treatment. We present a unique case of a spontaneous, subscapular abscess due to methicillin-resistant Staphylococcus aureus in a pediatric host, and we describe a surgical approach for adequate debridement.

Conclusion: The effective treatment of a subscapular abscess depends on an accurate, rapid diagnosis and effective surgical debridement. A modified Judet approach provides adequate access to the subscapular space for debridement.
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December 2017

Biomechanical comparison of ponte osteotomy and discectomy.

Spine (Phila Pa 1976) 2015 Feb;40(3):E141-5

*Department of Orthopaedic Surgery, Ferguson Laboratory, University of Pittsburgh, Pittsburgh, PA †Department of Spinal Surgery, the First Affiliated Hospital of University of South China, Hengyang City, Hunan Province, China ‡Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA; and §Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA.

Study Design: Biomechanical cadaver study.

Objective: To evaluate the relative effectiveness of Ponte osteotomies for spinal release in deformity correction.

Summary Of Background Data: Controversy exists as to the role of Ponte osteotomy in deformity correction surgery. Very little has been written about the biomechanical effects of Ponte osteotomy. Past biomechanical studies have been limited to application of forces through endplates, single functional units, or lack of comparison with anterior release.

Methods: Twelve fresh-frozen human full thoracic spinal units were tested for motion in axial rotation, flexion/extension, and lateral bending in a custom-designed robotic environment. Testing was repeated after sequential facetectomy and Ponte osteotomy (6 specimens) and compared with partial and full discectomy (6 specimens).

Results: Motion in axial rotation is increased 21% by Ponte osteotomy compared with 35% for full discectomy. Anterior displacement of the spinal column, creating lordosis, was increased 15% by Ponte osteotomy and 40% by full discectomy. Posterior displacement of the spinal column, creating kyphosis, was increased 23% by Ponte osteotomy and 89% by full discectomy. Finally, in coronal force application the Ponte osteotomy had virtually no effect (2%) compared with 40% increased motion by full discectomy.

Conclusion: Posterior Ponte osteotomy releases produced more motion than facetectomy alone in axial rotation and sagittal correction maneuvers, but had no effect on coronal correction. Anterior discectomy release destabilized spinal column significantly more than posterior releases in all force applications. Despite ample clinical experience demonstrating the effectiveness of posterior-only surgery, the biomechanical effect of Ponte osteotomies is modest.

Level Of Evidence: N/A.
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February 2015

Clinical Decision Making in Early Wound Drainage Following Posterior Spine Surgery in Pediatric Patients.

Spine Deform 2014 Mar 5;2(2):104-109. Epub 2014 Mar 5.

Department of Orthopaedic Surgery, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, 4401 Penn Avenue, Pittsburgh, PA 15224, USA. Electronic address:

Study Design: Retrospective.

Objectives: To identify the clinical factors suggestive of infected and non-infected drainage to help clinical decision making.

Summary Of Background Data: Differentiating between drainage caused by a benign seroma and deep spinal infection may be difficult in the early postoperative period.

Methods: Institutional spine surgery database was searched to identify the cases that were taken back to the operating room for drainage from the surgical wound in the early postoperative period between 2000 and 2012.

Results: A total of 38 cases of early wound drainage (within 6 weeks postoperatively) were identified that were treated with opening all layers, irrigation, and debridement. Intraoperative cultures were sent in all cases. Twenty-five patients proved to have non-infected drainage and did not require further treatment. In 13 patients, infection was confirmed with intra-operative findings and cultures; these patients were treated with serial debridements. In 4 cases, implants had to be removed after multiple debridements (after a quiescent period). The group with non-infected drainage differed from the infection group in that most patients (21 of 25) had non-neuromuscular deformities, whereas 77% of the infected group had neuromuscular etiology (10 of 13) (p = .0004). Average number of days to revision was 8.5 (range, 5-14 days) for the non-infected group. Of the 25 patients, 23 presented in the first 10 days. In the infected group, average number of days to revision was 19. Ten of the 13 patients presented on postoperative day 14 or later. Logistic regression analysis showed a significant association between increased likelihood of infection and increased time from the index procedure (p = .0085).

Conclusions: The findings suggest that early presenting drainage in pediatric idiopathic spine deformity is often not infected. Drainage, especially presenting after the second postoperative week in neuromuscular patients, proved to be mostly deep spinal wound infections.
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March 2014

Using the freehand pedicle screw placement technique in adolescent idiopathic scoliosis surgery: what is the incidence of neurological symptoms secondary to misplaced screws?

Spine (Phila Pa 1976) 2014 Feb;39(4):286-90

From the Department of Orthopaedic Surgery, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA.

Study Design: Retrospective case series.

Objective: This study evaluated the incidence of postoperative neurological symptoms after a freehand pedicle screw insertion technique in idiopathic posterior scoliosis surgery.

Summary Of Background Data: It is generally accepted that pedicle screws can be inserted by a freehand technique in the thoracic and lumbar spine in patients with adolescent idiopathic scoliosis (AIS) with a very low frequency of major complications. The prevalence of clinically significant screw misplacement, with or without the need for revision surgery is less well defined.

Methods: Between January 1, 2000, and October 2, 2012, five hundred fifty-nine patients with AIS had thoracolumbar posterior instrumented spine surgery at the Children's Hospital of Pittsburgh. Each patient's chart and radiographs were reviewed and only those with AIS were included. Patients with neuromuscular and syndromic diagnoses were excluded as well as those with congenital or traumatic etiologies, incomplete charts, less than 3 months of follow-up and those without pedicle screws. The records were studied for complaints of radicular pain, neurological deficit, or severe headache that could be indicative of potential screw misplacement.

Results: Four hundred eighty-one patients with 5923 pedicle screws met the inclusion criteria. Nine patients (1.9%) developed symptoms and underwent computed tomographic scanning. Six patients were found to have pedicle screw malposition (8 screws) and 3 of these patients underwent revision surgery. Of the 3 revision patients, 2 presented with radicular symptoms (leg pain) and 1 with an orthostatic headache due to cerebrospinal fluid leakage. At the final follow-up, all revision patients had complete symptom resolution. In total, there were 8 symptomatic, misplaced pedicle screws (0.14%) in 6 patients (1.25%).

Conclusion: During a 12-year period in a dedicated pediatric orthopedic hospital using the freehand placement technique, the incidence of symptomatic misplaced pedicle screws was exceedingly low.

Level Of Evidence: 4.
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February 2014

Pediatric cervical spine trauma.

J Am Acad Orthop Surg 2012 Apr;20(4):192; author reply 192-3

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April 2012

The effect of posterior spinal releases on axial correction torque: a cadaver study.

J Child Orthop 2011 Apr 10;5(2):109-13. Epub 2011 Feb 10.

Purpose: Posterior only approaches for spinal deformity are increasingly popular and posterior spinal release is utilized to gain flexibility for correctional maneuvers. Prior biomechanical data support the use of facetectomy and rib head resection for gaining flexibility in the sagittal and coronal planes but to date there has been no quantification of stiffness reduction provided by these techniques for axial correction through a pedicle screw construct. We sought to determine the contribution of posterior spinal releases (facetectomy, rib head resection) on axial plane stiffness.

Methods: Four fresh-frozen human cadavers were instrumented with fixed angle pedicle screws in the thoracic spine. The torque needed to produce 25° axial deflections at individual spinal segments (levels T5-T11) was measured using a custom needle deflection torque device attached to commercially available vertebral rotating construct. After the intact specimen was tested, torque measurements were repeated following a full facetectomy and posterior rib head resection

Results: Complete facetectomy resulted in an 18% decrease of torque needed to produce 25° of axial deformity compared to the intact specimen (P < 0.001). Rib resection added an additional 36% decrease in torque (P < 0.001).

Conclusions: Complete facetectomies (Ponte or Smith-Petersen osteotomies) decrease the force required to rotate spinal segments with respect to the axial plane by approximately one-fifth. Posterior rib head resection should be considered to further loosen the spine if additional axial correction is desired.
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April 2011

Intramuscular air as a complication of pulse-lavage irrigation. A case report.

J Bone Joint Surg Am 2009 Dec;91(12):2937-40

Department of Orthopaedics, University of New Mexico Hospital, MSC10 5600, Albuquerque, NM 87131, USA.

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December 2009

Prospective, surgeon-randomized evaluation of crossed pins versus lateral pins for unstable supracondylar humerus fractures in children.

J Pediatr Orthop B 2009 Mar;18(2):93-8

Department of Orthopaedic Surgery, University of New Mexico, Carrie Tingley Hospital, Albuquerque, New Mexico 87131, USA.

Controversy exists concerning pin placement for supracondylar humerus fractures in children. Both crossed pin and lateral only pin configurations have shown good results; however, prospective studies are lacking. We present a prospective, surgeon-randomized study comparing crossed pin (group A, n = 20) versus preferential lateral only pin (group B, n = 20) fixation for displaced supracondylar humerus fractures. There was no difference in Baumann's angle (P>0.75), the humerotrochlear angle (P>0.85), or final elbow range of motion (P>0.25). Both groups had stable reductions and clinically normal alignment. The only complication in both groups was a transient ulnar nerve irritation, despite no intraoperative evidence of nerve violation with a nerve stimulator. One patient in each group required modification of the operative plan. In group B, one patient had a medial pin inserted because of medial comminution extending proximally limiting available lateral pin placement. In group A, the surgeon elected to use lateral pins only because of an obviously subluxating ulnar nerve. In conclusion, we recommend orthopedic surgeons treating unstable pediatric supracondylar humerus fractures be facile with both medial and lateral pin placement.
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March 2009

Effect of cultural factors on outcome of Ponseti treatment of clubfeet in rural America.

J Bone Joint Surg Am 2009 Mar;91(3):530-40

University of New Mexico Carrie Tingley Hospital, 1127 University Boulevard N.E., Albuquerque, NM 87102, USA.

Background: Nonoperative management of clubfoot with the Ponseti method has proven to be effective, and it is the accepted initial form of treatment. Although several studies have shown that problems with compliance with the brace protocol are principally responsible for recurrence, no distinction has been made with regard to whether the distance from the site of care affects the early recurrence rate. We compared early recurrence after Ponseti treatment between rural and urban ethnically diverse North American populations to analyze whether distance from the site of care affects compliance and whether certain patient demographic characteristics predict recurrence.

Methods: One hundred consecutive infants with a total of 138 clubfeet treated with the Ponseti method were followed prospectively for at least two years from the beginning of treatment. Early recurrence, defined as the need for subsequent cast treatment or surgical treatment, and compliance, defined as strict adherence to the brace protocol described by Ponseti, were analyzed with respect to the distance from the site of care, age at presentation, number of casts needed for the initial correction, need for tenotomy, and family demographic variables.

Results: Of eighteen infants from a rural area who had early recurrence, fourteen were Native American. The families of these children, like those of all of the children with early recurrence, discontinued orthotic use earlier than was recommended by the physician. Discontinuation of orthotic use was related to recurrence, with an odds ratio of 120 (p < 0.0001), in patients living in a rural area. Native American ethnicity, unmarried parents, public or no insurance, parental education at the high-school level or less, and a family income of less than $20,000 were also significant risk factors for recurrence in patients living in a rural area. Intrinsic factors of the clubfoot deformity were not correlated with recurrence or discontinuation of bracing.

Conclusions: Compliance with the orthotic regimen after cast treatment is imperative for the Ponseti method to succeed. The striking difference in outcome in rural Native American patients as compared with the outcomes in urban Native American patients and children of other ethnicities suggests particular problems in communicating to families in this subpopulation the importance of bracing to maintain correction. An examination of communication styles suggested that these communication failures may be culturally related.
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March 2009

Medial collateral ligament tear entrapped within a proximal tibial physeal separation: imaging findings and operative reduction.

Skeletal Radiol 2008 Oct 9;37(10):943-6. Epub 2008 Aug 9.

Department of Radiology, University of New Mexico, MSC10 5530, 1, Albuquerque, NM 87131-0001, USA.

Entrapped soft tissues such as periosteum and tendons have been described within joints and physeal fractures in the literature and frequently result in irreducible fractures and posttraumatic growth disturbances. We believe this case represents a novel presentation of acute, preoperative, magnetic resonance (MR) imaging diagnosis of a torn medial collateral ligament entrapped within a proximal tibial physeal separation. This case is presented with MR imaging and operative correlation of the findings.
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October 2008

A new look at the incidence of slipped capital femoral epiphysis in new Mexico.

J Pediatr Orthop 2008 Jul-Aug;28(5):529-33

Division of Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, University of New Mexico, Albuquerque, NM 87131, USA.

Purpose: Past epidemiological studies demonstrated a nearly fivefold lower incidence of slipped capital femoral epiphysis (SCFE) in New Mexico compared with Connecticut. A recent study demonstrated some regional variability but did not address this earlier finding. We sought to reexamine the incidence of SCFE in New Mexico to improve the understanding of the epidemiology and ultimately the disorder itself.

Methods: The discharge databases for the 11 major medical centers in the state were reviewed for the ICD-9 code for SCFE (732.2) for 1995 to 2006. The data were analyzed by comparison with the 2000 New Mexico census data. The incidence data are reported as cases per 100,000 boys aged 10 to 17 years and girls aged 8 to 15 years, as per Kelsey's original article.

Results: The incidence of SCFE in New Mexico for the study period was 5.99. This is a doubling of the reported incidence in the 1960s (2.13) and represents a statistically significant change (P < 0.001). More detailed analysis of our data demonstrated a statistically significant increase during 3-year intervals: 1995-1997, 2.27; 1998-2000, 2.75; 2001-2003, 4.73; and 2004-2006, 7.38. The mean age of onset was 12.2 years. There was a male to female ratio of incidence of 1.94:1. Relative frequencies by race were as follows: 4.63x for African Americans, 2.20x for Hispanics, and 2.20x for Native Americans. A preponderance of cases was treated at the state's only tertiary pediatric orthopaedic center: 168 to 15 in the remaining 10 centers.

Conclusions: The incidence of SCFE has increased dramatically in New Mexico since Kelsey's epidemiological study in 1970. Obesity is a patient factor that has changed over this same period. According to the National Health and Nutrition Examination Survey Data for 2003/2004, the rates of obesity have tripled since 1971. In New Mexico, 25% of high-school children are estimated to be overweight. However, according to a recent study examining a national database (compiled from 27 states), the national incidence of SCFE remained fairly constant at 10.8 per 100,000.Interestingly, as more patients are seen at a tertiary center for children's orthopaedics, the rate of diagnosis in New Mexico has risen to resemble national trends. In the 1960, that center was located in a remote site and did not provide acute care for children's musculoskeletal issues. Increased obesity in children and improved access to pediatric orthopaedic evaluation may have contributed to a significant increase in reported incidence of SCFE in New Mexico.
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November 2008

Adolescents with idiopathic scoliosis are not osteoporotic.

Spine (Phila Pa 1976) 2008 Apr;33(7):802-6

Department of Orthopaedics and Rehabilitation, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA.

Study Design: Case controlled study.

Objective: To explore the relative effects of body mass index (BMI) and the presence or absence of adolescent idiopathic scoliosis (AIS) on bone mineral density (BMD) as evidenced by Z-scores in adolescents.

Summary Of Background Data: Prior studies have identified adolescents with idiopathic scoliosis as having "osteoporosis" or "osteopenia," when only a small percentage of subjects in these studies actually had bone density that was clinically abnormal. The terms osteoporosis and osteopenia as used in adults cannot be applied to adolescents and children, as fracture risk has not been well correlated to Z-scores. As we had noted that our scoliosis patients of normal and heavy weight had normal Z-scores, this study was undertaken to explore the relationship of bone mineral density to body mass index in adolescents with and without scoliosis.

Methods: Dual energy x-ray absorptiometry (DXA) scans of 49 adolescents with adolescent idiopathic scoliosis were compared to 40 normal control adolescents. Z-scores were compared to reduce variability when comparing subjects of varying age and genders. Student t test or simple linear regression was used to explore relationships between Z-scores and clinical and demographic variables.

Results: In both groups of subjects, Z-score was most strongly correlated with BMI (P < 0.001). The presence of scoliosis had the effect of lowering the Z-score as if the individual had "lost" 3.4 BMI units.

Conclusion: Z-scores in subjects with and without scoliosis were most strongly correlated to BMI: thin patients had lower bone density, heavy patients had higher. The presence of scoliosis had an effect similar to subtracting 3.4 "BMI units," lowering the Z-score from what might otherwise be predicted. The "scoliosis effect" may be noticeable in thin individuals, pushing them to the "low for age" level, whereas in heavier individuals, the effect is negligible. No subjects in either group met the ISCD definition for osteoporosis.
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April 2008

Biomechanical analysis of pinning techniques for pediatric supracondylar humerus fractures.

J Pediatr Orthop 2006 Sep-Oct;26(5):573-8

Department of Orthopaedics and Rehabilitation, MSC10 5600, 1 University of New Mexico, Albuquerque, NM 87102-1715, USA.

Background: Closed reduction and percutaneous pin fixation is the recommended treatment of displaced (Gartland types 2 and 3) supracondylar humerus fractures. The need for a medial pin for maximal stability remains controversial. The purpose of this study was to develop a model of supracondylar humerus fractures simulating medial column comminution and to evaluate the torsional stability of various pin configurations recommended in the current literature.

Methods: Transverse cuts were made in synthetic humeri with a wedge taken from the medial aspect of the proximal fracture fragment in one half of the specimens to simulate medial column comminution. Each fracture was then reduced and fixed with 1 of 4 pin configurations using 0.062 in K-wires. The fixed specimens were then subjected to a torsional load producing internal rotation of the distal fragment. Rotation in degrees and the corresponding torque was recorded for statistical analysis.

Results: Specimens with the medial wedge removed demonstrated less torsional stability than their identically fixed counterparts with the intact medial column. In specimens with the intact medial column, the greatest torsional stability was achieved with the 2 lateral divergent and medial cross pin configuration followed by 3 lateral pins, then standard crossed pins with 2 lateral divergent pins demonstrating the least torsional stability. For the medial comminution group the 2 lateral, 1 medial pin construct again had the greatest torsional stability and 2 lateral pins the least. The standard crossed pin and 3 lateral pin constructs were not significantly different in the presence of medial comminution.

Conclusions: In a synthetic humerus model of supracondylar humerus fractures, medial comminution was shown to reduce torsional stability significantly in all pin configurations. There was no statistical difference in torsional stability between 3 lateral pins and standard crossed pins in specimens with medial comminution.
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December 2006