Not Just Small Adults: Operative Versus Nonoperative Treatment in Adolescent Tibial Shaft Fractures.

BACKGROUND: The standard of care for tibial shaft fractures in young children is nonoperative management, while in adults, operative treatment is considered the mainstay. There are no clear guidelines on preferred treatment for adolescents. PURPOSE: This paper aims to 1) identify clinical and radiographic characteristics predictive of malalignment and 2) determine if treatment type affects malalignment risk. METHODS: This retrospective cohort study identified patients aged 12 to 16 years old with a tibial shaft fracture at a Level 1 pediatric trauma center. The primary outcome of interest was malalignment, classified as meeting one or more of the following: >5° coronal angulation, >5° sagittal angulation, translation (cortical width or 100% displaced), and/or rotational deformity. Comparative analyses were done to identify risk factors for malalignment. RESULTS: A total of 162 patients were included-initial treatment was "planned nonoperative" for 102 patients and "planned operative" for 60 patients. The malalignment rate was 34% in the planned nonoperative group versus 32% in the planned operative group. In a multivariate regression, older patients [odds ratio (OR)=-0.07, 95% CI: -0.13 to -0.01; P =0.024] and those with 100% initial displacement (OR=-0.35, 95% CI: -0.64 to -0.05; P =0.021) had decreased odds of malalignment, and having increased sagittal angulation (OR=0.02, 95% CI: 0.01-0.04; P =0.002) and a fibula fracture (OR=0.22, 95% CI: 0.03-0.41; P =0.023) increased the odds of malalignment. There was no difference in the rate of malalignment by initial treatment ( P =0.289). Having a planned nonoperative treatment (OR=22.7, 95% CI: 14.0-31.5; P <0.001) and having a fibula fracture (OR=8.52, 95% CI: 0.59-16.45; P =0.035) increased the time immobilized. CONCLUSIONS: This study provides insight into factors affecting tibial shaft fracture alignment among patients aged 12 to 16 years. This study suggests that the risk of malalignment is higher among patients with increased initial sagittal angulation and concomitant fibula fractures, but the risk of malalignment is comparable in patients initially treated nonoperatively and operatively. Although healing parameters on average were similar, nonoperative treatment results in longer immobilization time and time for unrestricted weight bearing. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Developmental Dysplasia of the Hip From Birth to Adolescence: Clear Indications and New Controversies.

It is important to be knowledgeable about the latest information on the diagnosis and the evidence-based management of developmental hip dysplasia and dislocation from birth through adolescence. The focus should be on the effect of the problem; normal growth and development of the hip joint; and the pathoanatomy, natural history, and long-term outcomes of developmental dysplasia of the hip, hip subluxation, and dysplasia. Many controversies exist in the management of this complex spectrum of disorders.

Femoroacetabular impingement in ancient Nubia 1400-656 BC.

INTRODUCTION: There is significant recent interest in femoroacetabular impingement (FAI) in orthopaedics. The etiology of the cam deformity is unknown but has been hypothesized to be due to stresses from sporting activities in our modern society. Few archeological studies exist of femora and FAI. This study reviewed proximal femoral anatomy in a skeletal collection from the ancient Nile valley archeological site at Tombos 1400-656 BC. METHODS: Digital photographs of the femora were used to obtain angular measurements of the apparent neck shaft, true neck shaft, version, inclination, and α and ß angles of Nötzli. All photographs were reviewed by two orthopaedic surgeons for cam and pincer lesions. Sex and age of the specimens was determined when possible. A cam lesion was defined as any femur demonstrating an α angle > 50° or when a cam deformity was seen on visual inspection by both orthopaedic surgeons. Pincer lesions were identified upon visual inspection by both orthopaedic surgeons, when the femoral neck demonstrated impaction lesions, as pelvis radiographs could not be obtained. RESULTS: There were 126 unique femora; 69 female and 57 male. Age estimates were possible in 100 and was 15-24 years in 14, 25-34 years in 33, 35-49 years in 28, 50-69 years in 17, and ≥ 70 years in 8. There were nine femora (seven individuals) with cam lesions (7%) and five femora (four individuals) with pincer lesions (4%). One demonstrated a combined lesion. CONCLUSION: FAI existed in ancient Nile valley inhabitants and is thus not only a product of modern day life style athletics. This contrasts with Native Americans living in Ohio 700-1000 AD where no FAI was identified. This difference is likely due to combinations of different types of activity, diet, and genetics. Further research of ancient populations is needed to further answer this question. LEVEL OF EVIDENCE: IV-cohort study.

Prospective evaluation of in situ screw fixation for stable slipped capital femoral epiphysis.

Purpose: We aimed to determine which variables were associated with persistent symptoms or need for further surgery in patients treated with in situ fixation for stable slipped capital femoral epiphysis. We hypothesized that patients with greater proximal femoral deformity would require revision surgical intervention. Methods: We prospectively collected data on stable slipped capital femoral epiphysis patients who underwent in situ screw fixation at a single institution. Demographic and radiographic information, as well as patient-reported outcomes, were collected. Results: Forty-six patients (54 hips) with an average follow-up of 3.5 years (range: 2.0-8.5) and mean pre-op Southwick slip angle of 40.5° ± 19.4° were studied. We observed one complication following the index procedure (2%). Twelve hips (22%) went on to have a secondary procedure 2.7 ± 2.2 years after the index surgery. Severe slips were 14.8× more likely to undergo a secondary procedure than mild and moderate slips (p < 0.001). We found no correlation between slip severity and patient-reported outcomes (p > 0.6). Hips requiring a secondary procedure had significantly lower Hip disability and Osteoarthritis Outcome scores (76.8 ± 18.4) at final follow-up compared to hips that did not require additional surgery (86.8 ± 15.7) (p = 0.042). Conclusion: With minimum 2-year follow-up, 22% of patients required a secondary surgery. Patient-reported outcomes did not correlate with slip severity, but were found to be significantly higher in slipped capital femoral epiphysis patients that did not require a secondary procedure. Prophylactic treatment of all slip-related cam deformity was not found to be necessary in this prospective cohort. Patients with moderate-to-severe slips may require secondary surgery. Level of Evidence: Level II.

Telescoping screw fixation compared to traditional in situ screw fixation for slipped capital femoral epiphysis: clinical, radiographic and patient-reported outcomes.

This study compares clinical, radiographic and patient-reported outcomes among telescoping and traditional screws for the treatment of slipped capital femoral epiphysis (SCFE). We hypothesized that telescoping screws would prevent slip progression and result in preserved femoral neck growth and improved patient-reported outcomes. Traditional screws were compared to telescoping screws in a 2:1 matched cohort based on age at initial surgery, length of radiographic follow-up and whether or not the hip was pinned prophylactically or as a treatment for SCFE. Neck length and telescoping screw length were measured. The patient-reported outcomes were obtained at routine clinic visits. Total 42 hips were included with a mean follow-up of 24.5 ± 3.3 months. No patients developed avascular necrosis, chondrolysis or needed revision surgical procedures. Telescoping screws increased in length for the entire cohort by a mean of 6.0 ± 4.3 mm. Neck length change was not different in SCFE hips when treated with traditional screws vs. telescoping screws (P = 0.527). However, there was a difference in neck length change between the two groups when comparing prophylactically treated hips (P = 0.001). There were no significant differences in patient-reported outcomes among hips treated with telescoping screws compared to traditional screws. Traditional and telescoping screws are both effective for the treatment of SCFE. Telescoping screws have an advantage when prophylactically treating hips that are at risk of slipping as they don't lead to the coxa breva that is seen with traditional screws. However, both treatment methods had similar patient-reported outcomes.

Ligamentum Teres Transfer During Medial Open Reduction in Patients with Developmental Dysplasia of the Hip.

BACKGROUND: The ligamentum teres (LT) is believed to have a number of functions, including a role in hip stability, nociception, proprioception, vascular supply to the femoral head, and synovial fluid circulation. The LT is often excised in the process of performing a medial open reduction (MOR) of the hip. We sought to conduct a retrospective review of hips undergoing a MOR for dislocated infantile developmental dysplasia of the hip (DDH) to compare clinical and radiographic outcomes for patients with and without LT reconstruction. METHODS: We performed a retrospective review of 38 hips treated with MOR with or without LT reconstruction with minimum two-year follow-up. Radiographic outcomes were determined using the Severin score. Information regarding avascular necrosis (AVN), concomitant surgical procedures, repeat dislocation, subsequent surgery, limp, pain, and range of motion symmetry was recorded. RESULTS: Eighteen hips that underwent MOR with LT reconstruction were compared to 20 hips that underwent MOR without LT reconstruction. Mean follow up for this cohort was 70.1 months (median: 61.8; Range: 24.2 to 182.2 months). The group with LT reconstruction had an 11% rate of AVN, the group without LT reconstruction had a 15% rate of AVN (p=1.0) No hips in either group re-dislocated or had pain at final follow up. Two hips (5%) had a limp at most recent follow up, all were in the group that did not receive a LT reconstruction (p=0.488). Three hips (17%) in the LT reconstruction group and one hip (5%) in the other group had asymmetrical hip range of motion at final follow up (p=0.328). CONCLUSION: This study offers preliminary data to suggest that ligamentum teres reconstruction is a safe procedure that can minimize the risk for subluxation or re-dislocation that can occur within the post reduction hip spica cast. Although in this study, the patients who did not have LT reconstruction had a similar re-dislocation rate, we believe that ligamentum teres preservation is a useful adjunct to medial open reduction, especially in centers that may only treat occasional cases or have less experience in applying an excellent hip spica cast.Level of Evidence: III.

Increased Hip Intracapsular Pressure Decreases Perfusion of the Capital Femoral Epiphysis in a Skeletally Immature Porcine Model.

BACKGROUND: Increased intracapsular hip pressure is thought to be one of the possible etiologies of femoral head avascular necrosis after intra-articular proximal femoral fractures or acute slipped capital femoral epiphysis. The purpose of this study was to evaluate the relationship between intra-articular hip pressure (IAP) and epiphyseal perfusion pressure (EPP), and its dependency on skeletal maturity using a porcine model. METHODS: Seven female Yorkshire-hybrid pigs were used to study the direct relationship between IAP and EPP. A needle inserted into the capsule provided both IAP monitoring and saline infiltration until IAP was above mean arterial pressure (MAP). Video simultaneously documented IAP, EPP, MAP. Parameters for all trials in each hip were averaged and compared between the 2 age groups. Significance was P<0.05. RESULTS: Four young hips (in pigs 10.3±1.0 wk, 27.4±2.0 kg) and 5 older hips (21.1±0.1 wk, 89.4±7.1 kg) were studied. There was no significant difference in the MAP (50.0±11.8 and 55.5±7.0 mm Hg respectively, P=0.411) between the 2 age groups. In the older hips, biphasic EPP persisted despite increasing IAP to an average of 177 mm Hg over MAP. In the young pigs, the biphasic EPP waveform ceased with increased IAP to an average of 28 mm Hg over MAP. Biphasic waveforms returned once IAP fell to an average of 5 mm Hg over MAP. CONCLUSIONS: Increased IAP resulted in tamponade of epiphyseal perfusion in the young, but not in the older hips. An intact physis may preclude intraosseous metaphyseal vessels from penetrating the epiphysis, leaving it vulnerable to retinacular artery tamponade. CLINICAL RELEVANCE: The IAP and EPP relationship has direct clinical practice implications. Hip capsulotomy and decompression in young patients with intra-articular proximal femoral fractures and increased intracapsular pressure may decrease avascular necrosis risk.

Narrative Review of Complications Following DDH Treatment.

BACKGROUND: The purpose of this narrative review was to survey the literature for common complications following treatment of DDH in children less than 4 years old. METHODS: The Pubmed database was queried. Search result titles were reviewed to identify papers that were pertinent to the topic. Abstracts for these papers were obtained and read, and a subset of these were selected for review of the complete manuscript. RESULTS: 92 manuscripts were reviewed. Residual dysplasia, redislocation, and osteonecrosis are the primary complications of treatment in this age group. In the long term, hips without complications related to DDH treatment tend to do well, although a significant percentage of them will inevitably require joint replacement surgery. CONCLUSION: Although there is excellent potential for a good outcome when DDH is diagnosed and treated under age 4 years, osteonecrosis continues to be a concern with all treatment methods. A subset of patients from this young cohort will continue to have residual dysplasia or recurrent dislocation requiring return to the operating room.

3D Characterization of Acetabular Deficiency in Children with Developmental Dysplasia of the Hip.

BACKGROUND: The purpose of this study is to determine if a quantitative method can be used to identify differences in 3D morphology between normal and developmentally dysplastic hips and to identify specific areas of undercoverage in children with DDH compared to age- and sex-matched controls. METHODS: Subjects were included if they were typically developing children with no other underlying conditions affecting their musculoskeletal system and had an available pelvic CT scan (67 hips). Custom software was used to measure standard variables defining acetabular morphology (version, tilt, surface area). Acetabuli were divided into equal octants; coverage angles were measured for each octant of interest. Variables were compared with age- and sex-matched controls (128 hips) using analysis of variance or the Mann-Whitney test. RESULTS: Hips with DDH were more anteverted compared to normal hips (DDH: 22.6˚, Control: 16.4˚, p < 0.001). The surface area was similar between groups. 28% of hips had a global deficiency, 24% were anteriorly deficient, 19% were laterally deficient, 10% were anteverted (under covered anteriorly and over covered posteriorly), 3% were posteriorly deficient, and 15% of hips had borderline undercoverage. None of the hips in this cohort were found to be retroverted. CONCLUSIONS: This is the first study to quantify the 3D acetabular deficiency in children with DDH compared to age- and sex-matched controls. We found wide variability in coverage patterns among dysplastic hips. It is imperative to define the specific acetabular deficiency for each individual patient prior to surgical correction. LEVEL OF EVIDENCE: III - Case-control study.

"Multiligamentous" Injuries of the Skeletally Immature Knee: A Case Series and Literature Review.

Multiligamentous knee injuries occur rarely in the pediatric population. Few reports are available in the existing literature; furthermore, no longitudinal studies regarding the choice of treatment and long-term outcomes for this unique population have been published. To fill this knowledge gap, the literature on multiligamentous injuries of the knee in the adult population is commonly used as a guideline in clinical decision making for children and adolescents. However, the developing bone and physis are often weaker than the ligamentous structures of the knee-particularly during periods of rapid growth-and may be the first to fail in the event of injury or trauma. Bony avulsion fractures and peri-physeal fractures, rather than mid-substance ligamentous ruptures, may result. Patients with skeletal immaturity may therefore present with different patterns of multiligamentous injury after acute trauma to the knee. This article describes the clinical presentation, our treatment approach, and short-term outcomes for three pediatric patients with multiligamentous injuries of the knee and reviews the current literature relating to these uncommon injuries.

A Genetic Test Predicts Providence Brace Success for Adolescent Idiopathic Scoliosis When Failure Is Defined as Progression to >45 Degrees.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To determine whether a genetic test is associated with successful Providence bracing for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Genetic factors have been defined that predict the risk of progression of AIS in a polygenic fashion. From these data, a commercially available genetic test, ScoliScore, was developed. It is now used in clinical practice for counseling and to guide clinical management. Bracing is a mainstay of treatment for AIS. Large efforts have been made recently to reduce potential confounding across studies of different braces; however, none of these have considered genetics as a potential confounder. In particular, ScoliScore has not been evaluated in a population undergoing bracing. METHODS: We conducted a retrospective cohort study in which we identified a population of AIS patients who were initiated with Providence bracing and followed over time. Although these patients did not necessarily fit the commercial indications for ScoliScore, we contacted the patients and obtained a saliva sample from each for genetic analysis. We then tested whether ScoliScore correlated with the outcome of their bracing therapy. RESULTS: We were able to contact and invite 25 eligible subjects, of whom 16 (64.0%) returned samples for laboratory analysis. Patients were followed for an average of 2.3 years (range, 1.1-4 y) after initiation of the Providence brace. Eight patients (50.0%) progressed to >45 degrees, whereas the other 8 patients (50.0%) did not. The mean ScoliScore among those who progressed to >45 degrees was higher than that among those who did not (176 vs. 112, P=0.030). CONCLUSIONS: We demonstrate that a genetic test correlates with bracing outcome. It may be appropriate for future bracing studies to include analysis of genetic predisposition to limit potential confounding.

The Antiquity of the Cam Deformity: A Comparison of Proximal Femoral Morphology Between Early and Modern Humans.

BACKGROUND: The precise etiology of cam impingement continues to be incompletely understood. The prevailing hypothesis posits that the deformity arises as a developmental injury prior to skeletal maturation. There is a possible evolutionary role, with an aspherical femoral head affording upright humans better stability. We set out to identify the antiquity of the cam deformity to better understand the comparative roles of modern behavior and evolution in its development. METHODS: We used 249 physical specimens of femora from the Libben osteological collection, a set of bones from an ancient population who lived between the eighth and the eleventh century. These femora were photographed in four different orientations, and six specific proximal femoral angles were measured. The values were also compared with those from modern human femora using the Student t test, with a two-tailed p value of 0.05 denoting significance. RESULTS: In total, 249 femora from 175 individuals were included in the final analysis. The ages of the individuals ranged between seventeen and fifty-five years. Interobserver and intraobserver correlation was good or excellent for all variables measured. Compared with modern populations, ancient human hips were significantly more anteverted (19.96° versus 12.85°; p < 0.001) and varus (true neck-shaft angle, 121.96° versus 129.23°; p < 0.001). The alpha angle was significantly lower in ancient humans (35.33° versus 45.61°; p < 0.001), and none of the ancient femora met the modern criteria for a cam deformity (an alpha angle of >50°). CONCLUSIONS AND CLINICAL RELEVANCE: It appears that the cam deformity was nonexistent among ancient humans and is perhaps predominantly a product of modern-day stresses. Further clinical investigation into behavioral modifications in adolescence is warranted to potentially prevent the development of deformity and impingement.

The importance of sex of patient in the management of femoroacetabular impingement.

Femoroacetabular impingement (FAI), a recently described hip condition in adolescents and young adults, typically manifests as activity-related hip pain. Characteristic physical findings include limited passive internal rotation of the affected hip and a positive impingement sign. Diagnostic imaging may reveal cam and/or pincer lesions, and associated intra-articular pathology (eg, labral tear, chondral damage) is common. When nonoperative treatment fails to adequately alleviate symptoms, surgery may be warranted. Both open and arthroscopic techniques have been effective. As our understanding of FAI continues to evolve, sex-based differences in incidence, presentation, and outcomes for patients with FAI have become apparent. Understanding the different ways in which males and females may present with FAI and then changing clinical practice patterns to accommodate these sexual dimorphisms will likely result in improved outcomes for each patient with symptomatic FAI.

Outcomes and unmet need for neonatal surgery in a resource-limited environment: estimates of global health disparities from Kampala, Uganda.

PURPOSE: Reported outcomes of neonatal surgery in low-income countries (LICs) are poor. We examined epidemiology, outcomes, and met and unmet need of neonatal surgical diseases in Uganda. METHODS: Pediatric general surgical admissions and consults from January 1, 2012, to December 31, 2012, at a national referral center in Uganda were analyzed using a prospective database. Outcomes were compared with high-income countries (HICs), and met and unmet need was estimated using burden of disease metrics (disability-adjusted life years or DALYs). RESULTS: 23% (167/724) of patients were neonates, and 68% of these survived. Median age of presentation was 5days, and 53% underwent surgery. 88% survived postoperatively, while 55% died without surgery (p<0.001). Gastroschisis carried the highest mortality (100%) and the greatest mortality disparity with HICs. An estimated 5072 DALYs were averted by neonatal surgery in Uganda (met need), with 140,154 potentially avertable (unmet need). Approximately 3.5% of the need for neonatal surgery is met by the health system. CONCLUSIONS: More than two thirds of surgical neonates survived despite late presentation and lack of critical care. Epidemiology and outcomes differ greatly with HICs. A high burden of hidden mortality exists, and only a negligible fraction of the population need for neonatal surgery is met by health services.

Only prolonged time from abstraction found to affect viable nucleated cell concentrations in vertebral body bone marrow aspirate.

BACKGROUND CONTEXT: Vertebral body-derived bone marrow aspirate (BMA, with an appropriate carrier) is a potential alternative to traditional iliac crest bone graft for use in spinal fusion surgery. No studies have looked at the effect of different temporary handling/storage conditions on the osteoprogenitor potential of BMA. This is especially important because aspirate, as with cancellous and/or cortical grafts, may be extracted some time before actual implementation in regular clinical use. PURPOSE: To characterize factors that affect BMA cell concentration during routine spinal instrumentation, this study examined whether cell counts change significantly between the second pedicle aspirated and the first pedicle harvested at the same vertebral level. This study also aims to examine the optimal perioperative storage conditions for BMA obtained from the vertebral body. STUDY DESIGN: In vitro concentrations of viable cells were determined in BMA harvested from the first and second pedicles on every vertebral level, and after 1 hour of storage in different perioperative conditions. PATIENT SAMPLE: BMA was harvested from 28 pedicles from seven patients undergoing lumbar instrumented fusion surgeries. OUTCOME MEASURES: The outcome measure included viable nucleated cell concentrations in BMA. METHODS: After obtaining HIC approval from our institution, 28 vertebral marrow aspirates (obtained from seven patients) were evaluated. Based on prior work, 4-mL aspirates from each pedicle were evaluated. BMA was aspirated from both pedicles of two vertebral levels per patient. Samples were divided and placed in different storage conditions to examine the effect of laterality (first versus second pedicle aspirated per level), temperature, media, and time, on nucleated cell counts. No funding was received for this study, and the authors disclose no study specific conflicts of interest. RESULTS: Cell count was not significantly different between the first or second side aspirated for each vertebral level. Similarly, no significant differences were found for samples after 1 hour of storage at different temperatures (0 °C, room temperature, or 37 °C) or media (none, saline, essential media). Of the conditions examined, time from aspiration was the only variable found to have an impact on nucleated cell counts (p=.003). The viable cell count decreased to less than half by 4 hours. CONCLUSION: As vertebral BMA is increasingly considered as a bone grafting option, the field would be remiss not to consider factors that could affect cell viability after abstraction and before implementation. We expected a greater effect of perioperative storage conditions than was observed. Although the variables evaluated might show small effects on cell viability in a larger study, this would not be expected to be significant. In the current study, only prolonged time from abstraction could be shown to have a significant effect on cell viability.

Optimal aspiration volume of vertebral bone marrow for use in spinal fusion.

BACKGROUND CONTEXT: Bone marrow aspirate (BMA) has shown promise as a bone graft option in spinal fusion. The vertebral body is a convenient source for marrow aspirate as it is accessed in routine course of pedicle screw instrumentation. Studies have relied on data from the iliac crest to determine optimal aspiration volume from the vertebral body. PURPOSE: This study is designed to determine the optimal aspiration volume for BMA taken from the vertebral body. STUDY DESIGN: Prospective clinical study. PATIENT SAMPLE: Data are drawn from 18 pedicles and 180 aspirations. The average age of the subjects was 50.3 years, and the subject pool comprised five men and seven women. OUTCOME MEASURES: Nucleated cell count and alkaline phosphatase staining colony forming units. METHODS: Ten 1 mL aliquots of BMA were incrementally aspirated through a cannulated pedicle tap for each instrumented vertebral body. The numbers of nucleated cells per mL of BMA were analyzed with a hemocytometer, and the percentage of osteoprogenitor cells per mL aspirate were estimated by an alk phos production assay. The study was funded through departmental funds, and none of the authors have any conflicts of interest to report related to the study. RESULTS: Nucleated cell count decreased with increasing aspirate number (p<.001). The average cell count for the first mL was 45.8 million cells. Cell counts did not differ by age or sex (p=.943 and p=.685, respectively). Likewise, osteoprogenitor cell percentage decreased with increasing aspirate number (p<.001). CONCLUSIONS: The 2 mL aspirate volume has been defined as ideal for the iliac crest, but there has been no analogous assessment of the effect of aspiration volume for other sources such as the vertebral body. This information is important for the clinical implementation of vertebral body aspirations if volume, cells, and presumably performance, of this potential bone graft option are to be optimized for spine cases. Our data show a direct relationship between increasing aspiration number and decreasing osteoprogenitor cellular concentration, with a drop to 50% of the original aspirate cell count by the 4th mL aspirate. The vertebral body is a potentially exciting source of osteoprogenitor cells that can be implemented for a variety of spinal uses.

Biomechanical comparison of endplate forces generated by uniaxial screws and monoaxial pedicle screws.

Current surgical treatment of idiopathic scoliosis involves the use of various segmental instrumentation. Various pedicle screws have allowed for improved correction. Although monoaxial screws have improved rotational control compared with polyaxial screws, their use may increase screw-bone interface or vertebral endplate forces if not inserted in an exactly straight trajectory. Uniaxial screws potentially decrease these forces while retaining the advantages of monoaxial screws with respect to better rotational control. The purpose of this study was to compare the vertebral endplate forces with monoaxial or uniaxial screws when being reduced to a rod. Thirty-two plastic, surrogate T11 vertebrae were prepared with monoaxial (n=16) or uniaxial (n=16) screws. Screw angles relative to inferior vertebral endplates were assessed with lateral radiographs. The vertebrae were fixed to a load cell, and loads were measured as the screw was reduced to a rod. Monoaxial screws demonstrated a linear progression of endplate force with increasing screw angle. Uniaxial screws demonstrated minimal endplate force until approximately 20°, coinciding with screwhead excursion angle. As this maximum excursion angle was passed, uniaxial screws demonstrated a force slope similar to the monoaxial screws.The measured endplate forces should be equivalent to forces at the screw-bone interface. The reduced force with uniaxial screws is expected to have less cranial-caudal plow potential as the screw is coupled to a rod for deformity correction. This could have potential implications for screw failure, especially in less dense bone.

Routine imaging for anterior cervical decompression and fusion procedures: a survey study establishing current practice patterns.

The number of anterior cervical decompression and fusion procedures performed annually in the United States rose 8-fold from 1990 to 2004. Imaging for anterior cervical decompression and fusion procedures contributes to health care costs and exposes patients and staff to radiation. Despite this, no standard of care for such imaging has been defined, and imaging practices have remained largely uncharacterized. The authors distributed a questionnaire at the 2011 Spine Study Group meeting. They received 72 responses (80% response rate) and included 67 in the analysis. All participants were attending spine surgeons practicing in the United States, 97% of whom had completed spine surgery fellowships. Median practice duration was 8 years. Practice type was evenly split between private and academic, and the median annual number of anterior cervical decompression and fusion procedures was 50. Intraoperatively, 68% of surgeons use fluoroscopy and 32% use plain radiographs; 60% take at least 1 image prior to incision; 78% place the localizer in the disk, whereas 22% place it in the vertebral body, and 45% always save these localizer images; 100% take images of the final construct before leaving the operating room, and 74% always save the final-construct images. Postoperatively but before discharge, 12% of surgeons take images in the recovery room, 33% take images in the radiology suite, and 2% take images in both locations. After discharge, surgeons follow their patients for a mean of 1.6 years, 96% with lateral views, 96% with anteroposterior views, 46% with flexion-extension radiographs, and 14% with computed tomography scans.

Chromosome-wide mapping of DNA methylation patterns in normal and malignant prostate cells reveals pervasive methylation of gene-associated and conserved intergenic sequences.

BACKGROUND: DNA methylation has been linked to genome regulation and dysregulation in health and disease respectively, and methods for characterizing genomic DNA methylation patterns are rapidly emerging. We have developed/refined methods for enrichment of methylated genomic fragments using the methyl-binding domain of the human MBD2 protein (MBD2-MBD) followed by analysis with high-density tiling microarrays. This MBD-chip approach was used to characterize DNA methylation patterns across all non-repetitive sequences of human chromosomes 21 and 22 at high-resolution in normal and malignant prostate cells. RESULTS: Examining this data using computational methods that were designed specifically for DNA methylation tiling array data revealed widespread methylation of both gene promoter and non-promoter regions in cancer and normal cells. In addition to identifying several novel cancer hypermethylated 5' gene upstream regions that mediated epigenetic gene silencing, we also found several hypermethylated 3' gene downstream, intragenic and intergenic regions. The hypermethylated intragenic regions were highly enriched for overlap with intron-exon boundaries, suggesting a possible role in regulation of alternative transcriptional start sites, exon usage and/or splicing. The hypermethylated intergenic regions showed significant enrichment for conservation across vertebrate species. A sampling of these newly identified promoter (ADAMTS1 and SCARF2 genes) and non-promoter (downstream or within DSCR9, C21orf57 and HLCS genes) hypermethylated regions were effective in distinguishing malignant from normal prostate tissues and/or cell lines. CONCLUSIONS: Comparison of chromosome-wide DNA methylation patterns in normal and malignant prostate cells revealed significant methylation of gene-proximal and conserved intergenic sequences. Such analyses can be easily extended for genome-wide methylation analysis in health and disease.