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Background: Previous research has suggested a correlation between pulmonary impairment and thoracic spinal deformity. The curve magnitude, number of involved vertebrae, curve location, and decrease in thoracic kyphosis independently contribute to pulmonary impairment, but the strength of these associations has been variable. The objectives of this study were to test the hypothesis that increased thoracic deformity is associated with decreased pulmonary function and to determine which, if any, radiographic measurements of deformity predict pulmonary impairment.Methods: Preoperative pulmonary function testing and radiographic examination were performed on 631 patients with adolescent idiopathic scoliosis. Correlation analysis and subsequent stepwise multiple regression analysis were carried out to assess the associations between radiographic measurements of deformity and the results of pulmonary function testing.Results: The magnitude of the thoracic curve, the number of vertebrae involved in the thoracic curve, the thoracic hypokyphosis, and coronal imbalance had a minimal but significant effect on pulmonary function. While these four factors were associated with an increased risk of moderate or severe pulmonary impairment, they explained only 19.7%, 18.0%, and 8.8% of the observed variability in forced vital capacity, forced expiratory volume in one second, and total lung capacity, respectively. The degrees of scoliosis that were associated with clinically relevant decreases in pulmonary function were much smaller than previously described, but the majority of the observed variability in pulmonary function was not explained by the radiographic characteristics of the deformity.Conclusions: Some patients with adolescent idiopathic scoliosis may have clinically relevant pulmonary impairment that is out of proportion with the severity of the scoliosis, and this may alter the decision-making process regarding which fusion technique will produce an acceptable clinical result with the least additional effect on pulmonary function. [ABSTRACT FROM AUTHOR]

Study Design: A radiographic and clinical outcomes analysis of 41 patients treated for thoracolumbar adolescent idiopathic scoliosis utilizing a single anterior rigid rod construct. Objectives: To evaluate the necessity of structural interbody support to improve primary curve correction and preserve or augment lordosis when used in conjunction with a single anterior rigid rod construct, to identify parameters that predict horizontalization of the lowest instrumented vertebra, adjacent disc angulation, and distal uninstrumented vertebrae, and to assess patient satisfaction following surgery. Background Data: Instrumentation-induced kyphosis has been a concern with nonrigid anterior systems used in the past for the treatment of scoliosis. Interbody structural support has been recommended to maintain appropriate sagittal profile when anterior systems are utilized. It has also been suggested that the use of structural interbody support creates a fulcrum to increase curve correction when compression is applied to the convexity of the deformity. However, the necessity of interbody structural support when used in conjunction with a rigid anterior system has not been previously evaluated in patients with adolescent idiopathic scoliosis. Materials and Methods: Forty-one patients mean age 15.9 years (range 12.1-18.6 years) with thoracolumbar adolescent idiopathic scoliosis underwent anterior spinal fusion using a single 6.0 to 6.5 mm solid rod construct between June 1995 and August 1999 performed by the senior author (T.G.L.). Four additional patients with thoracolumbar curves with similar anterior instrumentation over the same time period were lost to follow-up or had incomplete records and were not included in the study. Structural interbody support was used in 21 patients and packed morselized autograft alone was used in 20 patients. The patients in the group with packed morselized bone alone generally underwent surgery earlier in the series before the author began using structural interbody support on a regular basis. Each patient had a minimum follow-up of 3 years. Preoperative, initial, and most recent (>3 years) follow-up radiographs were reviewed to determine in each group Cobb angle measurements, flexibility of primary, secondary, and fractional curves, apical and end vertebral translation, lowest instrumented vertebral and caudal disc angulation, global coronal and sagittal balance, and sagittal Cobb measurements in both instrumented levels as well as lumbar lordosis (T12-S1). In addition, the SRS outcomes instrument was completed by 38 of 41 patients. Results: The mean preoperative primary curve in patients with structural support was 47 degrees (Group II) and 45 degrees in patients without structural support (Group I). Mean curve correction was to 13 degrees in Groups I and II. One patient in Group II became slightly more unbalanced at final follow-up; otherwise all were improved after surgery. Sagittal measurements over instrumented segments as well as total lumbar lordosis (T12-S1) was maintained between preoperative and final postoperative values in both groups. Similarly, in both groups, when horizontalization of the distal end instrumented vertebra was achieved on the preoperative reverse side-bending radiograph, more normal relationships were achieved between instrumented and distal noninstrumented segments (adjacent disc angulation and fractional lumbar curve) at final follow-up (P Conclusions: The use of interbody structural support does not appear to be necessary to maintain an appropriate sagittal profile or to maximize coronal curve correction when a rigid rod construct with packed morselized bone is used for the treatment of thoracolumbar adolescent idiopathic scoliosis. Parameters predicting horizontalization of the lower instrumented vertebra and uninstrumented segments below the construct were identified, which, if achieved, should predict an optimal long-term outcome. Clinical outcomes were very good in both groups. [ABSTRACT FROM AUTHOR]

Background: The lack of a reliable, universally acceptable system for classification of adolescent idiopathic scoliosis has made comparisons between various types of operative treatment an impossible task. Furthermore, long-term outcomes cannot be determined because of the great variations in the description of study groups.Methods: We developed a new classification system with three components: curve type (1 through 6), a lumbar spine modifier (A, B, or C), and a sagittal thoracic modifier (-, N, or +). The six curve types have specific characteristics, on coronal and sagittal radiographs, that differentiate structural and nonstructural curves in the proximal thoracic, main thoracic, and thoracolumbar/lumbar regions. The lumbar spine modifier is based on the relationship of the center sacral vertical line to the apex of the lumbar curve, and the sagittal thoracic modifier is based on the sagittal curve measurement from the fifth to the twelfth thoracic level. A minus sign represents a curve of less than +10 degrees, N represents a curve of 10 degrees to 40 degrees, and a plus sign represents a curve of more than +40 degrees. Five surgeons, members of the Scoliosis Research Society who had developed the new system and who had previously tested the reliability of the King classification on radiographs of twenty-seven patients, measured the same radiographs (standing coronal and lateral as well as supine side-bending views) to test the reliability of the new classification. A randomly chosen independent group of seven surgeons, also members of the Scoliosis Research Society, tested the reliability and validity of the classification as well.Results: The interobserver and intraobserver kappa values for the curve type were, respectively, 0.92 and 0.83 for the five developers of the system and 0.740 and 0.893 for the independent group of seven scoliosis surgeons. In the independent group, the mean interobserver and intraobserver kappa values were 0.800 and 0.840 for the lumbar modifier and 0.938 and 0.970 for the sagittal thoracic modifier. These kappa values were all in the good-to-excellent range (>0.75), except for the interobserver reliability of the independent group for the curve type (kappa = 0.74), which fell just below this level.Conclusions: This new two-dimensional classification of adolescent idiopathic scoliosis, as tested by two groups of surgeons, was shown to be much more reliable than the King system. Additional studies are necessary to determine the versatility, reliability, and accuracy of the classification for defining the vertebrae to be included in an arthrodesis. [ABSTRACT FROM AUTHOR]

The multiheme cytochromes from Thioalkalivibrio nitratireducens (TvNiR) and Escherichia coli (EcNrfA) reduce nitrite to ammonium. Both enzymes contain His/His-ligated hemes to deliver electrons to their active sites, where a Lys-ligated heme has a distal pocket containing a catalytic triad of His, Tyr, and Arg residues. Protein-film electrochemistry reveals significant differences in the catalytic properties of these enzymes. TvNiR, but not EcNrfA, requires reductive activation. Spectroelectrochemistry implicates reduction of His/His-ligated heme(s) as being key to this process, which restricts the rate of hydroxide binding to the ferric form of the active-site heme. The K M describing nitrite reduction by EcNrfA varies with pH in a sigmoidal manner that is consistent with its modulation by (de)protonation of a residue with pK a ≈ 7.6. This residue is proposed to be the catalytic His in the distal pocket. By contrast, the K M for nitrite reduction by TvNiR decreases approximately linearly with increase of pH such that different features of the mechanism define this parameter for TvNiR. In other regards the catalytic properties of TvNiR and EcNrfA are similar, namely, the pH dependence of V max and the nitrite dependence of the catalytic current-potential profiles resolved by cyclic voltammetry, such that the determinants of these properties appear to be conserved.

CymA (tetrahaem cytochrome c) is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis strain MR-1 identifies three low-spin His/His co-ordinated c-haems and a single high-spin c-haem with His/H(2)O co-ordination lying adjacent to the quinol-binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (approximately -240 mV) and low-spin (approximately -110, -190 and -265 mV) haems that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (E(m) = -80 mV) in the presence of NADH (E(m) = -320 mV) and an NADH-menadione (2-methyl-1,4-naphthoquinone) oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H2 oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a non-haem co-factor for quinol oxidation and that the reduced enzyme forms a 1:1 complex with its redox partner Fcc3 (flavocytochrome c3 fumarate reductase). The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.

Study Design: Multicenter analysis of 3 groups of patients who underwent surgical treatment for adolescent idiopathic scoliosis (AIS). OBJECTIVE.: To evaluate 3 surgical approaches to determine the modality that has the greatest influence on improving thoracic kyphosis., Summary of Background Data: AIS is characterized by thoracic hypokyphosis which may be restored to normal to varying degrees with surgery., Methods: A multicenter retrospective AIS surgical database was reviewed. Patients with only a structural main thoracic curve (Lenke 1, 2, or 3), and instrumentation of only the main thoracic curve were included. Lateral radiographs were analyzed to determine sagittal plane measurements before surgery, after surgery at 6 to 8 weeks, 1 year, and 2 years. The 3 groups were compared and statistical significance was defined as P < 0.05., Results: Three groups were analyzed: (1) ASF group (n = 135), Anterior spinal fusion and instrumentation, (2) PSF-Hybrid group (n = 86), PSF with proximal hooks, +/- apical wires and distal pedicle screws, and 3) PSF-Hooks group (n = 132), PSF with only hooks. All groups had similar preoperative coronal main thoracic curve magnitudes (ASF: 50.6 degrees , PSF-Hybrid: 49.1 degrees , PSF-Hooks: 52.0 degrees ) and thoracic kyphosis (ASF: 23.7 degrees , PSF-Hybrid: 19.3 degrees , PSF-Hooks: 21.9 degrees ). After surgery, the T5-T12 kyphosis was greater in the ASF group (25.1 degrees ) compared with PSF-Hooks (19.0 degrees ) and PSF-Hybrid (18.5 degrees (P < 0.05). At 1 year, thoracic kyphosis (T5-T12) remained greater in the ASF group (28.8 degrees ) compared with PSF-Hooks (22.6 degrees ) and PSF-Hybrid (20.2 degrees ) (P < 0.05), and was also greater at 2 years (29.9 degrees vs. 23.8.8 degrees and 19.7 degrees ) (P < 0.05). Kyphosis at the thoracolumbar junction was not seen in the PSF-Hybrid group. Lumbar lordosis increased only in the ASF group in response to the increase in thoracic kyphosis., Conclusion: ASFI is the best method to restore thoracic kyphosis when compared with posterior approaches using only hooks or a hybrid construct in the treatment of thoracic adolescent idiopathic scoliosis.

Study Design: A multicenter study of changes in Scoliosis Research Society (SRS) outcome measures after surgical treatment of adolescent idiopathic scoliosis (AIS)., Objective: To evaluate changes in patient determined outcome measures between 2 and 5 years after AIS surgery., Summary of Background Data: Current surgical procedures have been shown to improve subjective measures in patients with AIS. At 2-year follow-up, AIS patients reported significant improvement in all 4 preoperative domains of the SRS questionnaire. In addition, the major Cobb angle was shown to be negatively correlated with preoperative scores in the pain, general self-image, and general function domains. Five-year SRS scores have not been evaluated previously., Methods: A multicenter, prospectively generated database was used to obtain perioperative, radiographic, and SRS-24 outcomes data. The inclusion criteria were: a diagnosis of AIS, surgical treatment (anterior, posterior, or combined), a comprehensive set of radiographic measures, and completed preoperative, 2-year, and 5-year SRS questionnaires. Repeated measures analysis of variance was used to compare changes in patient responses for each of the 7 outcome domains. Univariate analysis of variance was used to compare the change in pain score at 5 years to the level of the lowest instrumented vertebrae and surgical approach. A correlation analysis was used to determine the association between changes in any of the radiographic variables and changes in SRS scores. The data were checked for normality and equal variances, and the level of significance was set at P < 0.01., Results: Forty-nine patients (42 women, 7 men; 14.2 +/- 2.1 year old; 5.4 +/- 0.6 years follow-up) met the inclusion criteria for this study. Thirty-seven of 49 (76%) of these patients underwent an open or thoracoscopic anterior procedure. SRS-24 scores improved significantly in 3 of the 4 preoperative domains at the 2-year visit. At 5 years postop, a statistically significant decrease in the pain score (4.2 +/- 0.6 to 3.9 +/- 0.9, P = 0.003) and a trend toward worsening scores in 4 other domains was observed; however, Patient Satisfaction scores remained unchanged. Lowest instrumented vertebrae and surgical approach could not be correlated to changes in the pain score. In addition, no correlation was found between changes in any of the 21 radiographic measures evaluated and changes in SRS scores., Conclusion: There was a statistically significant increase in reported pain from 2 to 5 years after surgical treatment; however, the etiology of worsening pain scores could not be elucidated. Given continued patient satisfaction, the clinical relevance of this small reduction remains unknown. Nevertheless, this observation deserves further evaluation and must be considered in relation to the natural history of this disease.

Study Design: : A review of the current literature using evidence-based medicine (EBM) regarding etiology, natural history, and treatment of Scheuermann kyphosis., Objective: : To provide current concepts for the rational evaluation and treatment of Scheuermann kyphosis supported by EBM., Summary of Background Data: : The literature concerning etiology, natural history, and treatment of Scheuermann disease has mixed views and recommendations, most of which are not strongly supported with levels of evidence., Methods: : A thorough database search was performed in order to obtain the best current information and levels of evidence on etiology, natural history, and treatment options for Scheuermann kyphosis based on EBM criteria., Results and Conclusion: : Scheuermann kyphosis is the most common cause of hyperkyphosis in adolescence. Its true etiology remains unknown, but there appears to be a strong genetic as well as an environmental contribution. The kyphotic deformity is frequently attributed to "poor posture" resulting in delayed diagnosis, and treatment indications remain debated because the natural history has not been clearly defined. When recognized early in adolescence with progressive kyphosis, bracing treatment will usually result in modest correction of the deformity. Symptomatic adolescents with severe deformity have demonstrated significant deformity correction following surgical intervention; however, clinical outcomes data are not yet available, and the studies available do not have strong levels of evidence.

Scheuermann's disease is the most common cause of structural kyphosis in adolescents. The kyphotic deformity is frequently attributed to "poor posture," resulting in delayed diagnosis and treatment. Indications for treatment remain somewhat debated, because the true natural history of the disease has not been clearly defined. Brace treatment is almost always successful in patients with kyphosis between 55 degrees and 80 degrees if the diagnosis is made before skeletal maturity. Kyphosis greater than 80 degrees in the thoracic spine or 65 degrees in the thoracolumbar spine is almost never treated successfully without surgery in symptomatic patients. Surgical treatment in adolescents and young adults should be considered if there is documented progression, refractory pain, loss of sagittal balance, or neurologic deficit. The major postoperative complication after surgical treatment is junctional kyphosis proximally or distally, which is usually related to not including all levels of the kyphosis or overcorrection of the deformity (>50%). With proper patient selection, excellent outcomes can be expected with nonoperative or operative treatment in patients with Scheuermann's disease.

Study Design: This is a retrospective multicenter analysis of a subset of 375 patients with thoracic adolescent idiopathic scoliosis (AIS) treated with either anterior (238) or posterior (137) fusion with preoperative or postoperative distal junctional kyphosis (DJK) >or=10 degrees ., Objectives: To determine the incidence of DJK before and after surgery in patients with AIS undergoing either anterior or posterior thoracic fusion, and provide recommendations for prevention., Summary of Background Data: DJK following surgical treatment for AIS may result in pain, imbalance, and unacceptable deformity. The true incidence of DJK following selective anterior or posterior instrumentation and fusion is unknown, as are "risk factors" for its development., Methods: Mean age at surgery was 14.4 years (range 9.1-20.9) in the anterior group and 14.7 years (range 10.2-20.7) in the posterior. Analysis included the Cobb and instrumented levels of the thoracic curves, and sagittal measurements, all on preoperative and 2-year follow-up standing 36-in radiographs., Results: In the anterior group, the incidence of preoperative DJK was 4.2%, and postoperative DJK was 7.1%. In the posterior group, the incidence of preoperative DJK was 5.0% and 14.6% after surgery. When postoperative DJK developed in the posterior group, mean postoperative T10-L2 was +17 degrees kyphosis compared to +2 degrees in the posterior group without DJK (P < 0.001). When postoperative DJK developed in the anterior group, mean postoperative T10-L2 was +12 degrees kyphosis compared to +2 degrees for the anterior group without DJK (P = 0.006). DJK was significantly more likely to occur in the posterior group if the Cobb was instrumented to less than Cobb +1 (P < 0.001)., Conclusions: It appears that both posterior and anterior instrumentation for thoracic curves must include the junctional level to prevent postoperative DJK when postoperative DJK is present. The presence of increased kyphosis after surgery in the T10-L2 region seen in both anterior and posterior groups that had postoperative DJK develop constitutes a "risk factor" for the development of DJK.

Study Design: This was an in vivo and in vitro investigation of a minimally invasive posterior tether system for fusionless modulation of sagittal plane growth in an immature sheep model., Objective: To determine whether fusionless modulation of spinal growth in the sagittal plane of an immature sheep model can be successfully performed., Summary of Background Data: Scheuermann's disease has been reported to affect 1% to 8% of the pediatric population. Varying degrees of spinal bone growth modulation has been successfully performed in the coronal plane of animal models. This represents the first attempt to modulate spinal growth in the sagittal plane in an animal model. Modulation of spinal growth in the sagittal plane may play a role in the treatment of pediatric kyphosis when brace treatment is unsuccessful., Methods: There were nine immature sheep posteriorly tethered and five control animals, all with identical follow-ups. Pedicle screws were placed in adjacent vertebrae, bilaterally, at the thoracolumbar junction and the lower lumbar spine. Polyethylene cords were passed subcutaneously, and tensioned to 20 lbs. Tethers were released in four sheep at 6 months and four at 12 months. At 12 months and 2 weeks, all animals were sacrificed., Results: At 13 months after surgery, the tethered groups had significantly less kyphosis and vertebral body wedging than the control group. In both the tethered groups, at 13 months after surgery, there was significantly less vertebral body wedging compared with the preoperative values. There was no evidence of facet arthropathy, but heterotopic ossification was seen in several specimens. Tethered spines had significantly less motion than control spines. Histologic evaluation demonstrated no detrimental results., Conclusions: Fusionless modulation of sagittal plane growth in an immature sheep model was successfully performed with changes in the overall sagittal profile of the instrumented segments and vertebral body wedging. Increased stiffness of the instrumented segments posttether release was thought to be related to heterotopic ossification. Results suggest that this may be a potential treatment for adolescents with Scheuermann's disease.

Study Design: Anterior single- and dual-rod instrumented human and ovine thoracolumbar spines, with and without structural interbody support (SIS), were biomechanically tested and compared in flexion, lateral bending, and torsion., Objective: To determine significant differences in global stiffness of the constructs in an attempt to clarify specific indications for each in the treatment of spinal deformities., Summary of Background Data: Single- and dual-rod anterior systems have been used without any consensus as to indications for one versus the other. The potential added benefit of incorporating SIS and transverse connectors (dual-rod) with these constructs has also not been fully explored., Methods: Four human cadaveric and six ovine spines were instrumented in single- and dual-rod constructs and biomechanically tested intact, postdiscectomy with and without SIS, with single- and dual-rod constructs, and with and without transverse connectors (ovine only). Biomechanical testing modes were flexion, lateral bending, and torsion., Results: In the human cadaveric specimens, testing in flexion revealed that SIS was the major contributing factor for construct stiffness. In lateral bending, stiffness of single- and dual-rod constructs with and without SIS was equivalent. In torsion, both single- and dual-rod instrumentation and SIS appeared to contribute to global stiffness. In ovine specimens, dual rods were stiffer than single-rod constructs and SIS played only a minor role. Transverse connectors appeared to significantly stiffen dual-rod constructs in torsion only., Conclusions: Dual-rod constructs with SIS appear to be the best combination for providing stiffness in anterior instrumentation. The addition of cross-links to anterior constructs does not appear to increase stiffness except in torsion.

Study Design: An in vitro biomechanical investigation to quantify the endplates resistance to compressive loads, in the thoracic and lumbar spine. Comparisons were made to determine the regional strength of the endplate, the optimal size and geometry of interbody support, and the effects of endplate removal on structural strength., Objectives: To biomechanically assess the regional variation of endplate strength in the thoracic and lumbar spine, the optimal geometry and cross-sectional area for structural interbody support, and endplate preparation techniques with respect to endplate failure or subsidence., Summary of Background Data: Anterior column interbody support plays an important role in spinal reconstruction. Subsidence of interbody structural support is a common problem and may be related to regional weakness of the endplate, the size and/or geometry of structural support, and the preparation of the endplate. Biomechanical data related to these issues should be of importance to spine surgeons and reduce the risk of subsidence and its inherent complications., Methods: The indentation tests were performed in three subgroups, each with a different set of test variables. The first test consisted of 65 vertebrae at six different endplate test positions using a 9.53-mm diameter indenter. The second test was performed on 48 vertebrae at a central endplate test site using three hollow and two solid cylindrical indenters of varying diameter. The third test was done using 24 vertebrae with the endplate intact, partially removed, or fully removed. All tests were run using human cadaveric specimen using both the superior and inferior endplates. The maximum load to failure (MLF) was determined for each test performed., Results: For all levels tested, the highest MLF occurred in the posterolateral region of the endplate. The lowest value occurred in the central and anterocentral regions for levels T7-L5 and T1-T6, respectively. Hollow indenters with a small diameter had the lowest MLF, whereas solid large-diameter indenters had the highest MLF. The ultimate compressive strength for all hollow indenters was significantly higher than all solid indenters. There was a significant reduction in the endplate strength with the complete removal of the endplate., Conclusions: The posterolateral region of the endplate provides the greatest resistance to subsidence while the central region provides the least resistance. A larger-diameter solid support has the greater MLF and the lower the risk of subsidence, suggesting a more efficient transfer of force to the endplate with the hollow indenters. Parameters such as the geometry of structural support and the position and preparation of the endplate can influence the resistance of an interbody support to subside. Partial removal of the endplate may provide both, for adequate mechanical advantage and a highly vascular site for fusion.

There is no generally accepted scientific theory for the etiology of idiopathic scoliosis. As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate of extant knowledge on important topics. This has been designated as an on-line Delphi discussion. The text for this EFG was written by Professor Thomas G Lowe MD and drawn from research carried out by himself and his co-workers on platelet calmodulin levels in patients with adolescent idiopathic scoliosis. To explain the relationship of platelet calmodulin levels to scoliosis curve changes in AIS brought about spontaneously, by brace treatment, or surgery Dr Lowe attributes the platelet calmodulin changes to paraspinous muscle activity and suggests that the calmodulin acts as a systemic mediator of tissues having a contractile system (actin and myosin). Controversy includes: 1) the lack of normal data and the large variability in baseline levels of platelet calmodulin, necessitating the use of the AIS subjects as their own controls; 2) calmodulin is not usually used as a marker of platelet activation; 3) whether the platelet calmodulin changes which appear to reflect an abnormality of a portion of the spine are related to local and/or regional changes in muscles, nervous system, or immature vertebrae. What is not controversial is the need for more research on platelets and the immature deforming skeleton in relation to etiology and prognosis.

Kyphosis of the thoracic or thoracolumbar spine is a common deformity in pediatric and adolescent populations. When it progresses to the point at which nonsurgical treatment is no longer an option, surgery is indicated. Surgical options available for the treatment of different types of pediatric kyphosis of the thoracic and thoracolumbar spine include posterior instrumentation and fusion, posterior instrumentation and fusion combined with anterior fusion, and anterior instrumentation and fusion.

Study Design: To evaluate the ability of single-rod anterior instrumentation to save or preserve fusion levels and improve thoracic hypokyphosis in patients with adolescent idiopathic thoracic, thoracolumbar, or lumbar scoliosis., Objective: To provide indications for single anterior rod instrumentation for the treatment of adolescent idiopathic scoliosis and demonstrate effectiveness in properly selected cases., Summary of Background Data: Posterior multisegmented dual rod instrumentation is the most commonly used instrumentation for the surgical treatment of adolescent idiopathic scoliosis. The issue of longer fusion levels and inability to correct hypokyphosis with posterior instrumentation continues to be debated in the literature. Anterior instrumentation has the ability in certain curve patterns to preserve distal and proximal levels as well as correct thoracic hypokyphosis., Methods: A brief discussion of the Lenke adolescent idiopathic scoliosis classification system is presented. Surgical treatment options for each of the curve types are discussed in detail., Results: Single-rod anterior instrumentation for adolescent idiopathic scoliosis will predictably save levels in Type I curves without hyperkyphosis as well as Type 5 curves; however, it is usually contraindicated in Type 2, Type 4, and Type 6 curves. Single-rod anterior instrumentation can occasionally be utilized in Type 3 curves if the magnitude of the lumbar curve is significantly less than the thoracic curve and the flexibility of the lumbar curve approaches 25 degrees on the side-bending radiograph., Conclusions: Single-rod anterior instrumentation will often saved one to three distal fusion levels when treating isolated major thoracic, thoracolumbar, or lumbar curves. Fusion levels should include upper to lower Cobb levels. Additionally, anterior single-rod instrumentation because its kyphogenic nature will predictably correct hypokyphosis of the thoracic spine.

Object: Sixty patients underwent instrumentation-assisted posterior transforaminal lumbar interbody fusion (TLIF) with resorbable polymer cages and autograft bone for degenerative disease. This article discusses the technique of TLIF and its early outcomes., Methods: Although the follow-up period is short and results are preliminary, no adverse events or complications were attributed to the resorbable polymer., Conclusions: Further multicenter clinical studies are underway with a minimum 2-year follow-up period chosen as an endpoint to provide insight as to the future of biodegradable polymers as spinal interbody devices.

Sixty patients from two centers have undergone instrumented transforaminal posterior lumbar interbody fusion (TLIF) with bioresorbable polymer cages and autograft bone for degenerative indications. This article discusses the technique of TLIF and its early outcomes. Although follow-up is short and results are preliminary, no adverse events or complications may be attributed to the bioresorbable polymer. Further multicenter clinical studies are underway with a minimum of 2 years of follow-up chosen as an endpoint to provide insight as to the future of biodegradable polymers as spinal interbody devices.

Objective: Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury., Design: Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique., Intervention: Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination., Main Outcome Measurements: Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors., Results: Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups., Conclusions: Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.

A prospective analysis of consecutive cases of lumbar fusion using the unilateral transforaminal posterior lumbar interbody fusion (TLIF) technique with pedicle screw fixation. The objective of the study was to assess the clinical and radiographic outcome of TLIF and describe the technique and indications in the treatment of degenerative disease of the lumbar spine. Forty patients treated with TLIF for degenerative diseases of the lumbar spine were followed up for a minimum of 2.5 years (mean: 36 months; range: 30-42 months). Twenty-three patients had degenerative disc disease alone, 13 had associated isthmic or degenerative spondylolisthesis, and 4 had recurrent disc herniations at the L4-L5 level. Thirty-six (90%) had solid fusions radiographically at latest follow-up. Seventy-nine percent had excellent or good clinical outcomes. Our patients demonstrated high fusion rates and patient satisfaction.

A prospective analysis of consecutive patients who had lumbar fusion using the unilateral transforaminal posterior lumbar interbody fusion with pedicle screw fixation is presented to assess the clinical and radiographic outcomes of the transforaminal posterior lumbar interbody fusion procedure and describe the technique and indication in the treatment of degenerative disease of the lumbar spine. Forty patients treated with transforaminal posterior lumbar interbody fusion for degenerative diseases of the lumbar spine (with anterior column deficiency) were followed up for a minimum of 3 years (mean, 3.4 years; range, 3-3.9 years). Radiographic assessment included plain and flexion and extension radiographs. Clinical outcome was based on pain relief, ability to do activities of daily living, and return to work. Thirty-six patients (90%) had solid fusions and at latest followup, segmental lordosis has increased in all patients. Eighty-five percent of patients had excellent or good clinical outcome(s). The unilateral transforaminal posterior lumbar interbody fusion provides bilateral anterior column support through a unilateral approach. The patients had high fusion rates and patient satisfaction as reported with similar complications found in other methods commonly used for spinal decompression and stabilization.

Study Design: A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients., Objective: To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level., Summary of Background Data: In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique., Material and Methods: Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12., Results: Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw., Conclusion: Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.

Current population studies characterize idiopathic scoliosis as a single-gene disorder that follows the patterns of mendelian genetics, including variable penetrance and heterogeneity. The role of melatonin and calmodulin in the development of idiopathic scoliosis is likely secondary, with indirect effects on growth mechanisms. Reported abnormalities of connective tissue, skeletal muscle, platelets, the spinal column, and the rib cage are all thought to be secondary to the deformity itself. Although no consistent neurological abnormalities have been identified in patients with idiopathic scoliosis, it is possible that a defect in processing by the central nervous system affects the growing spine. The true etiology of idiopathic scoliosis remains unknown; however, it appears to be multifactorial.

Study Design: Retrospective review of anterior and posterior fusions for treatment of adolescent idiopathic thoracic scoliosis., Objectives: To evaluate both the instrumented thoracic and the spontaneous lumbar curve corrections after treatment of the primary thoracic scoliosis by either anterior or posterior fusion., Summary of Background Data: Recent reports of thoracic scoliosis fusions have concentrated on the thoracic correction obtained by posterior segmental instrumentation systems. Coronal decompensation occurring because of curve progression with imbalance of the unfused lumbar spine has also been investigated. No report comparing spontaneous lumbar curve response after selective anterior versus posterior thoracic scoliosis fusions are available., Methods: One hundred twenty-three cases of primary thoracic-compensatory lumbar adolescent idiopathic scoliosis were treated by selective thoracic instrumentation and fusion with either an anterior (n = 70) or posterior (n = 53) single approach. Thoracic and lumbar Cobb measurements and lumbar apical translation parameters were assessed before surgery, 1 week after surgery, and 2 years after surgery on upright coronal radiographs. All patients had a minimum 2-year follow-up., Results: At 2-year follow-up, the percentage of thoracic curve correction was superior for the anterior (58%) versus the posterior (38%) group (P < 0.05), whereas the spontaneous lumbar curve correction was also superior for the anterior (56%) group versus the posterior (37%) group for all curve types investigated (P < 0.05). Both treatment groups consistently improved lumbar apical positioning after the thoracic fusion procedure., Conclusions: Spontaneous lumbar curve correction occurs consistently after both selective anterior and posterior thoracic fusion implying intrinsic ability of the lumbar spine to follow thoracic spine correction. In the current study, using multisegmented hook-rod systems posteriorly with intentional limitation of posterior thoracic correction to avoid decompensation, instrumented thoracic and spontaneous lumbar curve correction was statistically better after anterior thoracic instrumentation and fusion, with the results most dramatic for lumbar curve Type C (true King II curves).

Scheuermann's disease is the most common cause of structural kyphosis in adolescence. The mode of inheritance is likely autosomal dominant and the etiology remains largely unknown. Indications for treatment remain controversial because the true natural history of the disease has not been clearly defined. Brace treatment appears to be very effective if the diagnosis is made early. Surgical treatment is rarely indicated for severe kyphosis (> 75 degrees ) with curve progression, refractory pain, or neurologic deficit.

Study Design: This was a prospective study of two cohort groups of patients (one group receiving anterior instrumentation and the other posterior instrumentation) receiving treatment for thoracic idiopathic scoliosis., Objective: To present the 2-year postoperative results of a prospective multicenter study comparing the use of anterior instrumentation with that of posterior multisegmented hook instrumentation for the correction of adolescent thoracic idiopathic scoliosis., Summary of Background Data: Despite reports of satisfactory results, problems have been reported with posterior systems, including worsening of the lumbar curve after surgery and failure to correct hypokyphosis. Theoretically, the advantages of anterior instrumentation include prevention of lumbar curve decompensation by shortening the convexity of the thoracic curve. In addition, by removing the disc, better correction of thoracic hypokyphosis could be obtained., Methods: Seventy-eight patients who underwent an anterior spinal fusion using flexible threaded rods and nuts (Harms-MOSS instrumentation, De Puy-Motech-Acromed, Cleveland, OH) were analyzed and compared with 100 patients who underwent posterior spinal fusion with multisegmented hook systems. Parameters of comparison included coronal and sagittal correction, balance, distal lumbar fusion levels, and complication. All patients had idiopathic thoracic curves of King Types II to V. The average age at surgery was 14 years in each group, the average preoperative curve 57 degrees, and the minimum duration of follow-up for all patients 24 months. All data were collected prospectively and analyzed via Epl into statistical analysis (Centers of Disease Control, Atlanta, GA)., Results: Average coronal correction of the main thoracic curve was 58% in the anterior group and 59% in the posterior group (P = 0.92). Analysis of sagittal contour showed that the posterior systems failed to correct a preoperative hypokyphosis (sagittal T5 to T12 less than 20 degrees) in 60% of cases, whereas 81% were normal postoperatively in the anterior group. However, hyperkyphosis (sagittal T5 to T12 greater than 40 degrees) occurred after surgery in 40% of the anterior group when the preoperative kyphosis was greater than 20 degrees. Postoperative coronal balance was equal in both groups. An average of 2.5 (range, 0-6) distal fusion levels were saved using the anterior spinal instrumentation according to the criteria used for determining posterior fusion levels in this study. Selective fusion of the thoracic curve (distal fusion level T11, T12, L1) was performed in 76 of 78 patients (97%) in the anterior group as compared with only 18 of 100 (18%) in the posterior group. Surgically confirmed pseudarthrosis occurred in 4 of 78 patients (5%) in the anterior group and in 1 of 100 patients (1%) in the posterior group (P = 0.10). Loss of correction greater than 10 degrees occurred in 18 of 78 patients (23%) in the anterior group and in 12 of 100 patients (12%) in the posterior group (P = 0.01). Implant breakage occurred in 24 patients (31%) of the anterior group and in only 1 patient (1%) of the posterior group., Conclusions: 1) Coronal correction and balance were equal in both the anterior and posterior groups, even though the anterior group had the majority of curves (97%) fused short or to L1, whereas only 18% were fused short or to L1 in the posterior group. 2) In the anterior group there was a better correction of sagittal profile in those with a preoperative hypokyphosis less than 20 degrees. However, hyperkyphosis (with a mean of 54 degrees) occurred in 40% of those in the anterior group with a preoperative kyphosis of more than 20 degrees. 3) An average of 2.5 lumbar levels can be saved with anterior fusion and instrumentation according to the criteria used for choosing posterior fusion levels in this study. 4) Using the 3.2-mm flexible rod in this study, loss of correction, pseudarthrosis, and rod breakage were unacceptably highe

The system described by King et al. is the standard method for the classification of thoracic adolescent idiopathic scoliosis. Although it is widely used and referenced, its reliability and reproducibility among scoliosis surgeons are unknown. We used a scoliosis case-presentation format to examine the interobserver and intraobserver reliability of the classification of thoracic adolescent idiopathic scoliosis with the system of King et al. Eight active, current members of the Scoliosis Research Society reviewed twenty-seven full-length radiographs that had been made before operative correction of the scoliotic deformity. On the basis of these images, which included posteroanterior and lateral radiographs made with the patient standing as well as right and left forced-side-bending radiographs made with the patient supine, the reviewers assigned a type to each curve according to the classification system of King et al. Kappa coefficients were used to test statistical reliability. The mean interobserver reliability of the classification was only 64 per cent (range, 54 to 77 per cent) when the responses of seven of the reviewers were compared with those of one of the originators of the classification. The mean kappa coefficient was 0.49 (range, 0.27 to 0.73), which indicates poor reliability. When each reviewer's responses were compared with those of the other reviewers, the reliability was similarly poor (interobserver reliability, 55 per cent [range, 33 to 81 per cent] and mean kappa coefficient, 0.40 [range, 0.21 to 0.63]). Intraobserver reliability was evaluated in a trial in which five reviewers in a group setting were shown the same radiographs in a different order at two different viewings. Comparison of the results at the two viewings revealed a mean intraobserver reliability of 69 per cent (range, 56 to 85 per cent) and a mean kappa coefficient of 0.62 (range, 0.34 to 0.95), which indicates fair reliability. The current method of classification of adolescent idiopathic scoliosis does not appear to have sufficient intraobserver or interobserver reliability among scoliosis surgeons to portray curve types accurately. Thus, it may not help to guide treatment with use of modern spinal fixation methods.

Study Design: A prospective, randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy and safety of intrathecal morphine for postoperative analgesia after posterolateral lumbar fusion., Objectives: To compare the early postoperative analgesia in patients who receive a single dose of intrathecal morphine intraoperatively with that of patients using a patient-controlled analgesia pump only., Summary of Background Information: Although intrathecal morphine is used as an analgesic in a variety of medical and surgical conditions, very little has been published on its use after posterior lumbar spine surgery. Because the thecal sac is readily available during these procedures, the addition of a single injection of morphine before wound closure can be done with technical ease. If its efficacy and safety can be verified, then it could serve as a useful adjuvant to the postoperative analgesia regimen., Methods: Sixty-eight consecutive patients undergoing posterolateral lumbar fusion were randomly assigned to two groups. The experimental group was injected intrathecally with morphine 30 minutes before wound closure, and the control group was similarly injected with a placebo of normal saline solution. All patients were connected to an on-demand patient-controlled analgesia pump to provide any additional necessary analgesia. Their use of the patient-controlled analgesia pump was tabulated by counting the number of demands and the actual amount of morphine delivered. Additionally, a visual analog scale was used to assess pain levels at pre-established regular intervals., Results: The visual analog scale measurements were significantly lower for the intrathecal morphine group initially, but they surpassed those of the control group after 24 hours. Likewise, the number of patient-controlled analgesia pump demands and the amount of narcotic delivered initially were significantly lower in the experimental patients, but again reversed after the first postoperative day. The late rebound in pain and patient-controlled analgesia pump use did not reach statistical significance. There were no significant complications related to the analgesia., Conclusions: Intrathecal morphine can be safe and efficacious as an early postoperative analgesic after lumbar fusion when respiratory monitoring is used.

Study Design: One hundred forty four patients who underwent lumbar spine fusions had autografts placed on one side as a control and on the opposite side one of the following types of graft material was placed: iliac autograft, demineralized cancellous chips, demineralized cortical powder, demineralized cortical powder mixed with autograft, or mineralized cancellous chips. Alar anteroposterior and lateral postoperative radiographs were reviewed by three independent observers and graded for quality of fusion mass bilaterally. The follow-up was 14 to 27 months., Objectives: This study evaluated the efficacy of various types of ethylene oxide-sterilized allograft bone used for spine fusions and compared them with autograft iliac bone in the same patient., Summary of Background Data: Previous studies comparing autograft with allograft showed poorer fusion rates with allograft with posterior fusions. Most of the previous studies included smaller numbers of patients. No previous studies compared ethylene oxide-treated allograft with autograft., Results: An analysis of the radiographs at a minimum of 1 year postoperatively revealed significantly lower values when allograft alone or in combination with autograft was used in comparison to autograft alone., Conclusions: Ethylene oxide-treated allograft is inferior to autograft and should not be used for posterior lumbar fusions.

Study Design: This study compared preoperative and postoperative saggittal curves and spinal balance in patients undergoing spinal fusion with Cotrel-Dubousset instrumentation for severe kyphosis secondary to Scheuermann's disease. Also determined was patient satisfaction regarding relief of pain and correction of the deformity. Thirty two patients with kyphosis > 75 degrees underwent spinal fusion with Cotrel-Dubousset instrumentation., Objectives: To evaluate the initial and long-term correction of the primary kyphosis and changes in lumbar lordosis and sagittal balance, and to determine the incidence and etiology of junctional sagittal deformities., Summary of Background Data: The average preoperative kyphosis was 85 degrees (range, 75 degrees to 105 degrees) with an average correction at final follow-up of 43 degrees (range, 26 degrees to 65 degrees). Preoperative lumbar lordosis averaged 75 degrees (range, 58 degrees to 100 degrees) and at final follow-up averaged 55 degrees (range, 23 degrees to 74 degrees). Most of the patients demonstrated negative sagittal balance and became slightly more negatively balanced postoperatively., Results: Maintenance of correction postoperatively was excellent, with only a 4 degree average loss of correction. There was spontaneous reduction in lumbar lordosis of varying degrees. Proximal junctional kyphosis was associated with over-correction (> 50%) of the kyphotic deformity or a fusion starting short of the proximal vertebra in the measured kyphosis. Distal junctional kyphosis developed in patients whose fusion ended short of the first lordotic segment., Conclusions: This procedure appeared to yield good results when proper levels of fusion were selected and correction > 50% was not attempted.

The authors have reviewed the records of 36 patients with idiopathic scoliosis who underwent a single-stage anterior spinal fusion with Zielke instrumentation to determine if any adverse frontal or secondary sagittal deformities or changes in balance resulted from the surgery. Spontaneous correction of uninstrumented thoracic curves was noted in five patients with double-major curves, and frontal balance was maintained or improved after operation in all but four patients. Kyphosis was increased in the instrumented segments in all patients. In the uninstrumented segments, however, thoracic kyphosis and lumbar lordosis were decreased in all but five patients after operation, whereas overall sagittal balance was not adversely affected by the surgery in any patient.

Patients with untreated kyphosis secondary to Scheuermann's disease occasionally develop significant deformities associated with pain in adult life. When these painful deformities do not respond to conservative measures, surgery may be indicated. This report describes a two-stage surgical technique for correction of the deformity. First, an anterior spinal release and fusion is performed and is followed 7-10 days later by a posterior spinal fusion with double L-rod instrumentation. L-rod instrumentation has the advantage that no postoperative immobilization is necessary, which allows the patient to return to a relatively normal life-style in the immediate postoperative period. Excellent maintenance of correction of the deformity in these patients has occurred with no serious complication to date in 24 patients followed from 19 months to 4 years although "transient hyperesthesia" occurred in 16% of patients. A longer follow-up will be necessary to evaluate fully possible late pseudarthrosis and instrumentation failure in this group of patients.