Proximal Rod Research Articles

Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis-The Spinous Processes and Proximal Rod Contouring.

Proximal junctional kyphosis (PJK), as one of the most discussed problems after corrective surgery in adolescent idiopathic scoliosis (AIS), is still not fully clarified and seems to be multifactorial. Biomechanical and a few clinical studies have shown the influence of destruction of posterior ligaments by resection of spinous processes and some parameters concerning rod contouring as risk factors for PJK. To verify these results, 192 patients with AIS and corrective surgery via a posterior approach between 2009 and 2017 were included. Radiographic parameters were analyzed preoperatively (preOP), postoperatively (postOP), and with a mean follow up (FU) of 27 months. The participants were divided into two groups (PJK group and non-PJK group). The incidence of PJK was 15.6%. Contrary to the results of biomechanical studies, we could not find any significant influence of the spinous process resection. However, the PJK group had significantly larger preOP T4–T12 kyphosis (31.1° ± 13.93° vs. 23.3° ± 14.93°, p = 0.016). Furthermore, the PJK group showed a significantly larger rod contour angle (RCA) (8.0° ± 4.44° vs. 5.9° ± 3.28°, p = 0.003) and mismatch of postOP proximal junctional angle (PJA) and RCA (3.5° ± 5.72° vs. 0.9° ± 4.86°, p = 0.010) compared to the non-PJK group. An increase in the mismatch of postOP PJA and RCA (OR = 1.14, p = 0.008) and a high RCA are risk factors for PJK and need to be focused on by surgeons.

Unmatched rod contouring at the proximal end predisposes to occurrence of junctional kyphosis in early-onset scoliosis patients undergoing traditional growing rods treatment

Study designA retrospective case series.ObjectiveTo investigate whether unmatched rod contouring at the proximal end predisposed to the occurrence of proximal junctional kyphosis (PJK) in early-onset scoliosis (EOS) patients after traditional growing rods (TGR) treatment.Summary of background dataTGR treatment has become a mainstay of treatment for EOS patients. PJK is one of the most common alignment-related complications.MethodsA consecutive series of EOS patients who had undergone TGR treatment were retrospectively reviewed. They were divided into PJK and non-PJK groups according to the occurrence of PJK or not. Demographic data, surgical strategies, and radiographic parameters were recorded and compared between groups. Proximal junctional angle (PJA) was defined as the angle between the caudal endplate of the UIV and the cephalad endplate of the second supradjacent vertebra above the UIV, while proximal rod contouring angle (PRCA) was defined as the angle of proximal rod contouring, which was represented by the angle between the cephalad endplate of the UIV and the caudal endplate of the second vertebra caudal to the UIV. Unmatched proximal rod contouring was regarded if the postoperative PRCA-PJA difference was greater than 5°.ResultsThis study finally included 73 patients. The mean age at the index surgery was 6.5 ± 2.2 years (range, 2–10 years). Mean follow-up lasted 5.0 ± 1.7 years (range, 2–9 years). They received mean 4.6 ± 1.6 lengthening procedures. There were 13 patients who were observed with PJK (18%). In comparison with the non-PJK group, the PJK group showed a larger preoperative major curve (82 ± 21° vs 70 ± 17°, P = 0.041) and global kyphosis (57 ± 6° vs. 44 ± 15°, P = 0.044). In addition, the PJK group had significantly larger postoperative PJA (10 ± 3 vs. 5 ± 3, P<0.001) and greater postoperative PJA-PRCA (6 ± 3 vs. 3 ± 3, P = 0.031). The proportion of patients with unmatched proximal rod contouring in PJK group was significantly higher than that in the non-PJK group (69% vs. 25%). Multiple logistic regression showed that preoperative GK>50°, postoperative PJA>10 and postoperative unmatched proximal rod contouring were the risk factors in predicting PJK after TGR treatment.ConclusionApproximately 18% EOS patients experienced PJK after TGR treatment. Unmatched proximal rod contouring may be an independent risk factor of PJK occurrence, in addition to greater preoperative GK and larger postoperative PJA.Level of evidence3.

Bone Fusion Morphology after Circumferential Minimally Invasive Spine Surgery Using Lateral Lumbar Interbody Fusion and Percutaneous Pedicle Screws without Bone Grafting in the Thoracic Spine: A Retrospective Study.

Background and Objectives: This study aimed to investigate the process and morphology of thoracic and lumbosacral bone fusion in patients with adult spinal deformity (ASD) who underwent circumferential minimally invasive spine surgery (CMIS) by lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screws (PPSs) without bone grafting in the thoracic spine and who have risk factors for bone fusion failure in the thoracic spine. Materials and Methods: This retrospective study included 61 patients with spinal deformities (46 women and 15 men) who underwent CMIS with LLIF and PPSs at our hospital after 2016 and completed a 3-year postoperative follow-up. The rate and morphology of bone fusion and rod fracture rate in the thoracic and lumbosacral vertebrae were evaluated. Patients were divided into the thoracic spine spontaneous bone fusion group and the bone fusion failure group. The data of various spinopelvic parameters and the incidence of complications were compared. The vertebral body conditions in the thoracic spine were classified as less degenerative (type N), osteophyte (type O), and diffuse idiopathic skeletal hyperostosis (DISH) (type D). Results: After three postoperative years, the bone fusion rates were 54%, 95%, and 89% for the thoracic, lumbar, and lumbosacral spine, respectively. Screw loosening in the thoracic vertebrae was significantly higher in the bone fusion failure group, while no significant differences were observed in the spinopelvic parameters, Oswestry Disability Index (ODI), and rate of proximal junctional kyphosis and rod fractures. Type N vertebral body condition and screw loosening were identified as risk factors for spontaneous bone fusion failure in the thoracic spine. Conclusion: This study indicated that spontaneous bone fusion is likely to be obtained without screw loosening, and even if bone fusion is not obtained, there is no effect on clinical results with the mid-term (3-year) results of CMIS without bone grafting in the thoracic spine.

Математичне моделювання остеосинтезу черезвертлюгових переломів типу А1 із застосуванням різних металевих фіксаторів

Із метою визначення оптимального виду остеосинтезу при оперативному лікуванні черезвертлюгових переломів типу А1 проведено комп’ютерне моделювання напружень на металеві фіксатори (пластина DHS та PFN-стрижень). Визначено, що найбільш біомеханічно обґрунтованою при черезвертлюгових переломах типу А1 є модель PFN-стрижня у варіанті без застосування гвинтів для дистального блокування, про що свідчать мінімальне напруження на металевому фіксаторі та наявність оптимальної мікрорухливості між кістковими відламками. Проведене дослідження дозволить визначити диференційований підхід до лікування хворих із черезвертлюговими переломами стегнової кістки, покращить ефективність надання медичної допомоги цій категорії тяжких хворих.

P107. Impact of upper instrumented vertebra and lordosis morphology on acute proximal junctional fracture following adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Acute proximal junctional Fracture (PJF) is a challenging complication of adult spinal deformity (ASD) surgery. Upper instrumented vertebra (UIV) orientation has been proposed as a risk factor of acute PJF. Adjust UIV orientation by lordosis morphology during ASD surgery could reduce the occurrence of acute PJF. <h3>PURPOSE</h3> The purpose of this study is to analysis the effect of UIV orientation on acute PJF. And we tried to find out the relationship between UIV orientation and lordosis morphology. This strategy is thought to reduce acute PJF by adjusting lordosis morphology during surgery. <h3>STUDY DESIGN/SETTING</h3> A retrospective study. <h3>PATIENT SAMPLE</h3> A total of 187 patients (mean age 71.7 years) ASD patients underwent long-segment fusion from thoracolumbar vertebra to pelvis and followed up for more than 1 year. <h3>OUTCOME MEASURES</h3> Description and analysis of X-ray changes. <h3>METHODS</h3> Comparative analysis was performed on spinopelvic parameters including UIV parameters (UIV slope angle and horizontal distance from UIV center to C7 plumb line[C7PL]) between PJF and non-PJF group. And correlation analysis between UIV parameters and lordosis morphologic parameters (postoperative lumbar lordosis, lordosis correction degree, lordosis apical vertebra level and lordosis distribution index [LDI]) were performed. <h3>RESULTS</h3> Acute PJF incidence was 17.2% (32/187). PJF group had more UIV slope (20.6° vs 18.6°, p=0.045) and PJF group's UIV was located more posteriorly (-5.6mm vs +11.4mm, p<0.001). In condition that UIV slope was above 18.6° and UIV was located behind C7PL, acute PJF incidence was 75.0% (15/20). In condition that UIV slope was less than 18.6° and UIV was located in front of C7PL, acute PJF incidence was 1.9% (1/54). In correlation analysis, UIV slope had significant correlation with postoperative lumbar lordosis (r=0.422, p<0.01) and lordosis correction degree (r=0.239, p<0.05). And UIV-C7PL distance had significant negative correlation with apical vertebra level (r=-0.243, p<0.01) and LDI (r=-0.260, p<0.01). <h3>CONCLUSIONS</h3> UIV with large slope and located behind C7PL increases the risk of acute PJF occurrence. To avoid this situation while preserving sufficient lordosis correction, proper proximal rod contouring is needed to reduce UIV slope. And proper apical vertebra positioning and LDI lowering is needed to place UIV anteriorly. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Molecular structure of the intact bacterial flagellar basal body.

The bacterial flagellum is a macromolecular protein complex that enables motility in many species. Bacterial flagella self-assemble a strong, multi-component drive shaft which couples rotation in the inner membrane to the microns-long flagellar filament that powers bacterial swimming in viscous fluids1–3. We here present structures of the intact Salmonella flagellar basal body4, encompassing the inner membrane rotor, drive shaft, and outer membrane bushing, solved using cryo-electron microscopy to resolutions between 2.2 and 3.7 Å. The structures reveal molecular details of how 173 protein molecules of 13 different types assemble into a complex spanning two membranes and a cell wall. The helical drive shaft at one end is intricately interwoven with the rotor component with both the export gate complex and the proximal rod forming interactions with the MS-ring. At the other end, the drive shaft distal rod passes through the LP-ring bushing complex, which functions as a molecular bearing anchored in the outer membrane via interactions with the lipopolysaccharide. The in situ structure of a protein complex capping the drive shaft provides molecular insight into the assembly process of this molecular machine.

Under-contouring of rods: a potential risk factor for proximal junctional kyphosis after posterior correction of Scheuermann kyphosis.

Scheuermann kyphosis (SK) could require surgical treatment in certain situations. A posterior reduction is the most widespread treatment so far, although the development of proximal junctional kyphosis (PJK) is one of the possible complications of this procedure. The contour of the proximal part of the rod could influence the occurrence of PJK in SK patients. The objective of this study was to analyze the impact of the proximal rod contour on the occurrence of a PJK complication in SK patients. This retrospective monocentric study was performed in the Nanjing Spine Surgery Department. All eligible patients had undergone posterior correction surgery with pedicle screws only between 2002 and 2017 and had at least 24 months of follow-up. The presence of PJK was quantified on radiographs using the proximal junctional angle (PJA > 10° at the last follow-up). The authors propose a new radiological parameter to measure the angulation of the proximal part of the instrumentation: the proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to the UIV. The patients were analyzed according to the presence or absence of PJK. A t-test, receiver operating characteristic (ROC) curve analysis, and logistic regression analysis were performed for statistical analysis. Sixty-two patients treated for SK were included in this study. The mean age was 18.6 ± 8.5 years, and the mean follow-up was 42.5 ± 16.4 months. The mean correction rate of global kyphosis was 46.4% ± 13.7%. At the last follow-up, 17 patients (27.4%) presented with PJK. No significant difference was found between the PJK and non-PJK groups in terms of age and other preoperative variables. A significant difference in the postoperative PCRA was found between the PJK and non-PJK groups (8.2° ± 4.9° vs 15.7° ± 6.6°, respectively; p = 0.001). A postoperative PCRA less than 10.1° predicted a significantly higher risk for PJK (p = 0.002, OR 2.431, 95% CI 1.781-4.133). Under-contouring of the proximal part of the rods (lower than 10°) is a risk factor for PJK after posterior correction of SK.

Risk Factors Related to Superior Facet Joint Violation During Lumbar Percutaneous Pedicle Screw Placement in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF)

To investigate the incidence of superior facet joint violation (FJV) during percutaneous pedicle screw placement in minimally invasive transforaminal lumbar interbody fusion, and assess the possible risk factors for FJV. An analysis of 91 patients with lumbar degenerative diseases treated with percutaneous pedicle screw placement via minimally invasive transforaminal lumbar interbody fusion from 2012 to 2018 was performed. Superior FJV was evaluated and graded by 3-dimensional lumbar computed tomography reconstruction. Analysis of possible risk factors included general condition of patients, anatomical characteristics of facet joint (FJ; axial, sagittal, and coronal diameters of FJ, facet angle, lumbar lordosis angle, lumbar lordosis index, and depth of lamina), and surgical factors (pedicle screw angle, screw-superior FJ distance, cranial angle, proximal rod length, and rod contouring). The overall violation rate of superior FJ was 34.07% (62/182), and high-grade violation rate was 16.06% (27/182). The logistic regression analysis revealed that body mass index ≥30 kg/m2 and pedicle screw placement at L5 were independent risk factors of FJV. Anatomical factors showed that the incidence of FJV was significantly increased when axial, sagittal, and coronal diameters of FJ were all ≥12 mm or FA was ≥40°. Surgical factors showed that the FJV group had a smaller pedicle screw angle and screw-superior FJ distance compared with the non-FJV group (P < 0.05). Body mass index ≥30 kg/m2 and pedicle screw placement at L5 were independent risk factors of superior FJV. FJV was more likely to occur in hypertrophic FJ (axial, sagittal, and coronal diameters ≥12 mm) or coronal orientation (FA ≥40°).

Biomechanical cadaver study of proximal fixation in a minimally invasive bipolar construct.

Biomechanical human cadaver study. To determine the three-dimensional intervertebral ranges of motion (ROMs) of intact and hook-instrumented thoracic spine specimens subjected to physiological loads, using an in vitro experimental protocol with EOS biplane radiography. Pedicle screws are commonly used in thoracic instrumentation constructs, and their biomechanical properties have been widely studied. Promising clinical results have been reported using a T1-T5 thoracic hook-claw construct for proximal rod anchoring. Instrumentation stability is a crucial factor in minimizing mechanical complications rates but had not been assessed for this construct in a biomechanical study. Six fresh-frozen human cadaver C6-T7 thoracic spines were studied. The first thoracic vertebrae were instrumented using two claws of supra-laminar and pedicle hooks, each fixed on two adjacent vertebrae, on either side of a single free vertebra. Quasi-static pure-moment loads up to 5Nm were applied to each specimen before and after instrumentation, in flexion-extension, right and left bending, and axial rotation. Five steel beads impacted in each vertebra allowed 3D tracking of vertebral movements on EOS biplanar radiographs acquired after each loading step. The relative ranges of motion (ROMs) of each pair of vertebras were computed. Mean ROMs with the intact specimens were 17° in flexion-extension, 27.9° in lateral bending, and 29.5° in axial rotation. Corresponding values with the instrumented specimens were 0.9°, 2.6°, and 7.3°, respectively. Instrumentation significantly (P < 0.05) decreased flexion-extension (by 92-98%), lateral bending (by 87-96%), and axial rotation (by 68-84%). This study establishes the biomechanical stability of a double claw-hook construct in the upper thoracic spine, which may well explain the low mechanical complication rate in previous clinical studies. Not applicable, experimental cadaver study.

259. Under-contoured proximal rod: a potential risk factor of PJK in Scheuermann's kyphosis

BACKGROUND CONTEXT Correction of kyphosis in Scheuermann's Kyphosis (SK) patients can be effectively achieved via a multilevel Ponte osteotomies pedicle screw-based instrumentation. However, the risk of developing proximal junctional kyphosis remains an important issue after surgeries for SK. The influence of the proximal rod contouring on the occurrence of PJK has not been investigated in SK patients. PURPOSE The aim of this study was to evaluate the influence of the proximal rod contouring on the radiographic results in patients with Scheuermann's Kyphosis. STUDY DESIGN/SETTING Single-center retrospective study. PATIENT SAMPLE This study included 59 patients with SK (57 men, 2 women), who had undergone posterior correction surgery between 2002 and 2015, and had been followed at least 12 months. OUTCOME MEASURES The proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to UIV (UIV-2). A PJK was defined by the presence of a proximal junctional angle (PJA) greater than 10° at the latest follow-up, and the increase of this angle by more than 10° compared with preoperatively. METHODS Patients were separated into 2 groups: PJK group and non-PJK group. Comparisons were performed in terms of T-test between these two groups. ROC curve analysis and logistic regression analysis were performed. RESULTS The mean age was 20.24 ± 9.47 years old and the follow-up average were 16.3 months ± 8.3. No significant difference was found between two groups with regards to their ages, the PJA and the PCRA at preoperative time. At the last follow-up, 31,7% of the patients developed PJK, the mean value of PJA was 19.21 ± 4.6 in PJK group and was 7.76 ± 3.72 in non-PJK group (p CONCLUSIONS Patients whose PCRA angle are lower than 10° after surgery are more likely to develop PJK, demonstrating that under-contouring of the proximal rod is a risk factor for PJK in SK. So, proximal portion of the rod should be bent more kyphotic (more than 10° ). FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Enhanced radial growth of Mg doped GaN nanorods: A combined experimental and first-principles study

We discuss the microstructural origin of enhanced radial growth in magnesium (Mg) doped single crystalline wurtzite gallium nitride (w-GaN) nanorods (NRs) grown by MBE, using electron microscopy and first-principles Density Functional Theory calculations. Experimentally, we observe that Mg incorporation increases the surface coverage of the grown samples as a consequence of an increase in the radial growth rate of the NRs. We also observe that the coalescence of NRs becomes prominent and the height at which coalescence between proximal rods occurs decreases with increase in Mg concentration. From first-principles calculations, we find that the surface free energy of the Mg doped surface reduces with increasing Mg concentration in the samples. The calculations further suggest a reduction in the adsorption energy and the diffusion barrier of Ga adatoms along [112¯0] on the side wall surface of the NRs as the underlying mechanism for the observed enhancement in the radial growth rate of GaN NRs. The physics and chemistry behind reduction of the adsorption energy of Ga ad-atoms on the doped surface are explained in the light of electronic structure of the relevant surfaces.

Variantes que mantienen el marco de lectura en el dominio Rod 1 proximal del gen FLNA se asocian con un predominio del fenotipo valvular

Introduction and objectivesX-linked cardiac valvular dysplasia is a rare form of male-specific congenital heart defect mainly characterized by myxomatous degeneration of the atrioventricular valves with variable hemodynamic consequences. It is caused by genetic defects in FLNA-encoded filamin A, a widely expressed actin-binding protein that regulates cytoskeleton organization. Filamin A loss of function has also been associated with often concurring neurologic and connective tissue manifestations, with mutations in the first half of the Rod 1 domain apparently expressing the full cardiac phenotype. We contribute to previous genotype-phenotype correlations with a multidisciplinary approach in a newly-described family. MethodsCardiologic, dysmorphologic, and genetic evaluation of available members were complemented with transcriptional and X-chromosome inactivation studies. ResultsA novel FLNA mutation c.1066-3C>G cosegregated with a male-expressed, apparently isolated, cardiac phenotype with no skewed X-inactivation pattern in female carriers. This variant was shown to result in an in-frame deletion of 8 amino acid residues near the N-terminal region of the protein. ConclusionsA nonimprinted, partial loss of function of filamin A proximal Rod 1 domain seems to be the pathogenetic mechanism of cardiac valvular dysplasia, with some cases occasionally expressing associated extracardiac manifestations.Full English text available from: www.revespcardiol.org/en

In-frame Variants in FLNA Proximal Rod 1 Domain Associate With a Predominant Cardiac Valvular Phenotype

Introduction and objectivesX-linked cardiac valvular dysplasia is a rare form of male-specific congenital heart defect mainly characterized by myxomatous degeneration of the atrioventricular valves with variable hemodynamic consequences. It is caused by genetic defects in FLNA-encoded filamin A, a widely expressed actin-binding protein that regulates cytoskeleton organization. Filamin A loss of function has also been associated with often concurring neurologic and connective tissue manifestations, with mutations in the first half of the Rod 1 domain apparently expressing the full cardiac phenotype. We contribute to previous genotype-phenotype correlations with a multidisciplinary approach in a newly-described family. MethodsCardiologic, dysmorphologic, and genetic evaluation of available members were complemented with transcriptional and X-chromosome inactivation studies. ResultsA novel FLNA mutation c.1066-3C>G cosegregated with a male-expressed, apparently isolated, cardiac phenotype with no skewed X-inactivation pattern in female carriers. This variant was shown to result in an in-frame deletion of 8 amino acid residues near the N-terminal region of the protein. ConclusionsA nonimprinted, partial loss of function of filamin A proximal Rod 1 domain seems to be the pathogenetic mechanism of cardiac valvular dysplasia, with some cases occasionally expressing associated extracardiac manifestations.

Novel phenotypic variant in the MYH7 spectrum due to a stop-loss mutation in the C-terminal region: a case report

BackgroundDefects of the slow myosin heavy chain isoform coding MYH7 gene primarily cause skeletal myopathies including Laing Distal Myopathy, Myosin Storage Myopathy and are also responsible for cardiomyopathies. Scapuloperoneal and limb-girdle muscle weakness, congenital fiber type disproportion, multi-minicore disease were also reported in connection of MYH7. Pathogeneses of the defects in the head and proximal rod region of the protein are well described. However, the C-terminal mutations of the MYH7 gene are less known. Moreover, only two articles describe the phenotypic impact of the elongated mature protein product caused by termination signal loss.Case presentationHere we present a male patient with an unusual phenotypic variant of early-onset and predominant involvement of neck muscles with muscle biopsy indicating myopathy and sarcoplasmic storage material. Cardiomyopathic involvements could not be observed. Sequencing of MYH7 gene revealed a stop-loss mutation on the 3-prime end of the rod region, which causes the elongation of the mature protein.ConclusionsThe elongated protein likely disrupts the functions of the sarcomere by multiple functional abnormalities. This elongation could also affect the thick filament degradation leading to protein deposition and accumulation in the sarcomere, resulting in the severe myopathy of certain axial muscles. The phenotypic expression of the detected novel MYH7 genotype could strengthen and further expand our knowledge about mutations affecting the structure of MyHCI by termination signal loss in the MYH7 gene.

Mismatch Between Proximal Rod Contouring and Proximal Junctional Angle: A Predisposed Risk Factor for Proximal Junctional Kyphosis in Degenerative Scoliosis.

A retrospective study. To investigate whether the mismatch between proximal junctional angle (PJA) and the proximal rod contouring contributed to the occurrence of postoperative proximal junctional kyphosis (PJK) in degenerative scoliosis. PJK is one of the complications in the treatment of degenerative scoliosis, the postoperative PI-LL mismatch and the increased rod stiffness are supposed to be the etiology of PJK. However, the impact of rod contouring on PJK has not been fully illustrated. A retrospective study was performed on 27 consecutive degenerative scoliosis patients (three males and 24 females) who underwent corrective surgery with more than 2-year follow-up. Radiographic parameters included proximal rod contouring angle (PRCA) and PJA at the three time-points. The subjects were divided into two groups: PJK group and non-PJK group with the definition of PJK as a PJA more than 10°. The mismatch between PRCA and post-op PJA, defined as the difference between PRCA and postop PJA of more than 5°, was then compared with PJK and non-PJK group. The patients' mean age was 60.48 ± 6.47 years old with a mean Cobb angle of 40.89 ± 14.33°. Twelve patients, with a mean PJA of 18.67 ± 5.31° at the last followup, were stratified into the PJK group, while the remaining 15 patients, with a mean PJA of 5.33 ± 2.47, were placed into the non-PJK group. A significant difference in the mismatch between post-op PJA and PRCA was observed between PJK and non-PJK group (8.83 ± 5.07° vs. 4.07 ± 2.91°, P = 0.005). Meanwhile the difference of mismatch between preop PJA and PRCA showed no statistical significance (5.16 ± 4.24° vs. 3.00 ± 2.48°, P = 0.109). Mismatch between rod contouring and postoperative proximal spinal curve may be a predisposed risk factor for PJK in degenerative scoliosis. 4.

Genetic analysis of revertants isolated from the rod-fragile fliF mutant of Salmonella.

FliF is the protein comprising the MS-ring of the bacterial flagellar basal body, which is the base for the assembly of flagellar axial structures. From a fliF mutant that easily releases the rod-hook-filament in viscous environments, more than 400 revertants that recovered their swarming ability in viscous conditions, were isolated. The second-site mutations were determined for approximately 70% of them. There were three regions where the mutations were localized: two in Region I, 112 in Region II, and 71 in Region III including the true reversion. In Region I, second-site mutations were found in FlgC and FlgF of the proximal rod, suggesting that they affect the interaction between the MS-ring and the rod. In Region II, there were 69 and 42 mutations in MotA and MotB, respectively, suggesting that the second-site mutations in MotA and MotB may decrease the rotational speed of the flagellar motor to reduce the probability of releasing the rod under this condition. One exception is a mutation in FlhC that caused a down regulation of the flagellar proteins production but it may directly affect transcription or translation of motA and motB. In Region III, there were 44, 24, and 3 mutations in FliG, FliM, and FliF, respectively. There were no second-site mutations identified in FliN although it is involved in torque generation as a component of the C-ring. Many of the mutations were involved in the motor rotation, and it is suggested that such reduced speeds result in stabilizing the filament attachment to the motor.

Special article: Update on the magnetically controlled growing rod: tips and pitfalls.

Magnetically controlled growing rods (MCGR) have become an important treatment option in young patients with spinal deformities. This device allows for gradual lengthening on an outpatient setting with continuous neurological monitoring in an awake patient. With its growing popularity and interest, this study reports the tips, pitfalls, and complications of the MCGR for management of scoliosis. On 3 June 2015 at the University of Hong Kong, 32 participants from 16 regions shared their experience with MCGR. Current indications for surgery include early-onset scoliosis patients. Adolescent idiopathic scoliosis and congenital scoliosis patients have less favourable outcomes. The number of instrumented levels should be minimised, as all instrumented levels must be included in the definitive fusion surgery. Rod contouring is important and owing to the straight portion of the rod housing the magnet, there is limited proximal rod portion for proper contouring, which may predispose to proximal junctional kyphosis. There is currently no consensus on the rod configuration, timing, frequency, technique, and amount of distraction. Risk factors for distraction failure include larger patients, internal magnets too close to each other, and magnets too close to the apex of the major curve. Future studies should resolve the issues regarding the technique of distraction, optimal frequency and amount of distraction per session. More comprehensive cost analyses should be performed.

Incidence and Risk Factors of Proximal Junctional Kyphosis in Surgically Treated Young Children with Scoliosis

Introduction Proximal junctional kyphosis (PJK) is a well-recognized postoperative phenomenon in adults and adolescents after scoliosis surgery; however, no reports have addressed the incidence, risk factors, and behavior of PJK in young children following spinal correction surgery. The objective of this study is to determine the incidence, risk factors, and behavior of PJK in young children undergoing posterior instrumented spinal fusion. Materials and Methods This study reviewed 61 consecutive young children with congenital scoliosis treated with posterior instrumented spinal fusion (≥ 4 levels) from 2009 to 2011 in our center. They were younger than 10 years at surgery and had a UIV located between TI and T11. They were followed-up for at least 2 years. PJK was defined by a proximal junctional angle greater than 10 degrees and at least 10 degrees greater than the corresponding preoperative measurement. Radiographic measurements were performed preoperatively, immediately after surgery, and at latest follow-up, including proximal junctional angle (PJA), thoracic kyphosis, lumbar lordosis, kyphosis angles at T1–UIV, and UIV–T12, as well as the matching of rod contour. Matched rod contour referred to the difference between the proximal instrumented region angle and the proximal rod curvature less than 5 degrees. Comparison was performed between patients with and without PJK. Results The average age at surgery was 5.4 years (2–10 years) and the average follow-up was 2.7 years (2–4 years). PJK developed in 11 of the 61 patients (incidence, 18%). PJK group had larger preoperative thoracic kyphosis (48.7 vs. 36.3 degrees), longer fusion levels (9.2 vs. 6.8 levels), and larger amount of kyphosis correction (20.8 vs. 11.7 degrees). In addition, proximal instrumentation failure and unmatching of rod contour were identified as risk factors significantly associated with the occurrence of PJK. In the PJK group, average PJA increased by 14.4 degrees after 3 to 6 months postoperatively and then by 2.5 degrees until final follow-up. Six patients had screw pullout at the upmost instrumented vertebra but none complained of pain or appearance problems. They received brace treatment and their PJK was resolved. Conclusion This study demonstrated that 18% of young children were observed with PJK after correction surgery for congenital scoliosis. PJK mainly occurred within 6 months postoperatively, and its risk factors included preoperative hyperkyphosis and over correction of kyphosis, proximal instrumentation failure, and unmatching of rod contour. Brace treatment served as a salvage option for PJK in young children.

Proximal migration of femoral telescopic rod in children with osteogenesis imperfecta.

Intramedullary telescopic rod fixation has been used for stabilization of the long bones in growing children who have osteogenesis imperfecta. Proximal migration of the rod is the most common complication of telescopic rodding in the femur. The purposes of this study were to evaluate incidence and temporal pattern of proximal migration of the femoral rod, and to investigate factors related to it. A total of 50 patients with osteogenesis imperfecta, who had femur stabilized by telescopic rod with T-piece, were the subjects of this study. In patients having both the femora stabilized, only 1 femur was randomly selected for analysis. Hence, in 50 femora, migration-free survivorship was analyzed using the Kaplan-Meier method, and association with possible risk factors was analyzed by Cox regression analysis using the proportional hazards model. Factors investigated in the analysis include age at the time of surgery, sex, purpose of the index surgery, residual or developing angular deformity of the femur, rod position at the distal physis, persistent cortical gap at fracture/osteotomy site, Sillence classification, and type of telescopic rod. Proximal migration was observed in 7 of 50 femora. Cumulative survival without proximal migration was 0.94 (95% CI, 0.87-1.01) in 1 year, and 0.85 (95% CI, 0.75-0.95) in 6 years. Factors significantly associated with proximal rod migration in Kaplan-Meier survivorship analysis and univariate Cox regression analysis were angular deformity, eccentric rod position at the distal physis, and persistent cortical gap. When these factors were analyzed by multivariate analysis, eccentric rod position at the distal physis was the only significant factor with a hazard ratio of 11.74. The risk of proximal rod migration can be reduced by complete correction of angular deformity and optimal placement of the rod at the distal physis. Our data also suggest that developing angular deformity or persistent osteotomy/fracture gap requires special attention at the possibility of proximal rod migration during follow-up. Level III, prognostic study.

A Clinical Study on Treatment of Flexion Contractures of Knee by Distraction Technique

Flexion contracture of knee is a major disability and very often the patient has to resort to a walking aid for mobility. Many methods have been described to correct the deformity and include exercise, casting, traction, soft tissue release and osteotomies. Deformity correction by gradual distraction of soft tissues has been successfully used in the treatment of congenital talipes equinovarus (CTEV), finger flexion etc. by the application of simple distractor rods. The present study was undertaken to assess the usefulness of this technique in correcting the flexion contracture of knee. This was a prospective study conducted in the Department of orthopedics, Teerthanker Mahaveer Medical College and research centre, after obtaining clearance from the ethics committee. The study included a total of 22 patients out of which 13 were females and 9 were males. The mean age of patients was 19.5 years (range 14–33 years). Four patients had bilateral deformity. Flexion contracture ranged between 40 to 90 degrees with an average preoperative contracture of 70 degrees. Patients who had contractures more than 90 degrees were not included in the study. Diagnosis included post polio residual palsy (19 cases), post burn contracture (2 cases) and rheumatoid arthritis (1 case). In all the cases simple distractor was used whereby two Denham's pin were passed in the distal femur and two in the proximal tibia and distractor rods were applied on both the sides. After achieving correction the distractor was kept in place for another 4–5 weeks. Average fixator time was 15.3 weeks. Patients were followed up for an average of 2.3 years.