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OBJECTIVETo demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).METHODSThe study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.RESULTSTen patients and 110 vertebral levels (T1-11) were measured. The patients' average age was 41.4 years (range 18-64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).CONCLUSIONSA more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.

Study Design: Retrospective cohort chart review., Objective: To determine the optimal lowest instrumented vertebra (LIV) following posterior segmental spinal instrumented fusion (PSSIF) of thoracic adolescent idiopathic scoliosis (AIS) with LIV at L2 or above., Summary of Background Data: Few studies evaluate the optimal LIV based on rotation or center sacral vertical line (CSVL)., Methods: A radiographic assessment of 544 thoracic major AIS patients (average age 14.7 years) with minimum 2 years' follow-up (average 4.1 years) after PSSIF was performed. The LIV was divided by CSVL: stable vertebra 1 (SV-1) if the CSVL fell between the medial walls of the LIV pedicles; SV-2 if between stable vertebra 1 and 3; and SV-3 if the CSVL did not touch the LIV. LIV was divided by rotation into: neutral vertebra 0 (NV-0) if the LIV was at or distal to the neutral vertebra; NV-1 if one vertebra proximal to the NV; NV-2 if two vertebrae proximal; and NV-3 if three vertebrae proximal to the NV., Results: The prevalence of adding-on (AO) or distal junctional kyphosis (DJK) at ultimate follow-up was 13.6%. Patients with AO or DJK had a higher rate of open triradiate cartilage, LIV not touching the CSVL, and more proximal to the NV (p < .05). Risk factors were SV-3 (39% vs. SV-2 14%, SV-1 9%, p < .05), NV-3 (35% vs. NV-2 9%, NV-1 6%, NV-0 12%, p = .000), open triradiate cartilage (43% vs. closed 13%, p < .05), lumbar C modifier (22% vs. B modifier 8%, A modifier 13%, p < .05), and Risser stage 0 (19% vs. 12% Risser 1-5, p < .05)., Conclusion: The prevalence of AO or DJK at ultimate follow-up of PSSIF for AIS with LIV at L2 or above was 13.6%. Risk factors included the CSVL outside the LIV, LIV 3 or more proximal to the NV, open triradiate cartilage, lumbar C modifier, and Risser stage 0., Level of Evidence: Level IV., (Copyright © 2017 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.)

Background: Spinal fusion surgery is a widely used surgical procedure for sagittal realignment. Clinical studies have reported that spinal fusion may cause proximal junctional kyphosis and failure with disc failure, vertebral fracture, and/or failure at the implant-bone interface. However, the biomechanical injury mechanisms of proximal junctional kyphosis and failure remain unclear., Methods: A finite element model of the thoracolumbar spine was used. Nine fusion models with pedicle screw systems implanted at the L2-L3, L3-L4, L4-L5, L5-S1, L2-L4, L3-L5, L4-S1, L2-L5, and L3-S1 levels were developed based on the respective surgical protocols. The developed models simulated flexion-extension using hybrid testing protocol., Findings: When spinal fusion was performed at more distal levels, particularly at the L5-S1 level, the following biomechanical properties increased during flexion-extension: range of motion, stress on the annulus fibrosus fibers and vertebra at the adjacent motion segment, and the magnitude of axial forces on the pedicle screw at the uppermost instrumented vertebra., Interpretations: The results of this study demonstrate that more distal fusion levels, particularly in spinal fusion including the L5-S1 level, lead to greater increases in the risk of proximal junctional kyphosis and failure, as evidenced by larger ranges of motion, higher stresses on fibers of the annulus fibrosus and vertebra at the adjacent segment, and higher axial forces on the screw at the uppermost instrumented vertebra in flexion-extension. Therefore, fusion levels should be carefully selected to avoid proximal junctional kyphosis and failure., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: The purpose of this study was to compare the sagittal spinopelvic parameters between young normal asymptomatic adults and older normal asymptomatic adults without localized segmental disc degeneration., Materials and Methods: Standing sagittal radiographs of the whole spine including the pelvis in 342 adult male volunteers (Group 1: n = 184, average age 21.2 years, range 19-28 vs. Group 2: n = 158, average age 63.8 years, range 53-79) were analyzed prospectively. Volunteers with history of spine operation, spinal disease, chronic pain in their back or legs, scoliosis, spondylolisthesis, 1-3 segmental disc space narrowing, and/or compression fractures in radiographs were excluded. The following parameters were included: thoracic kyphosis between T5 upper endplate (UEP) and T12 lower endplate (LEP), thoracolumbar kyphosis (T10 UEP - L2 LEP), T12 LEP-horizontal (H) angle (minus denotes EP above the H line), lumbar lordosis (T12 LEP - S1 UEP), lower lumbar lordosis (L4 UEP - S1 UEP), sacral slope, pelvic incidence and distances from C7 plumb/T12 plumb to the postero-superior endplate of S1. Group 2 (old men group) demonstrated larger thoracic kyphosis (30.1° ± 8.6° vs. 21.1° ± 7.8° in Group 1, P < 0.001), thoracolumbar kyphosis (10.0° ± 7.5° vs. 2.8° ± 7.1° in Group 1, P < 0.001), total lumbar lordosis at T12-S1 (57.3° ± 8.8° vs. 52.2° ± 9.2° in Group 1, P < 0.001), lower lumbar lordosis at L4-S1 (39.4° ± 6.7° vs. 32.4° ± 6.4° in Group 1, P < 0.001), a higher ratio of lower to total lumbar lordosis (69.5 ± 11.6 vs. 62.7 ± 10.6 % in Group 1, P < 0.001) and T12 LEP-H angle (-20.4° ± 5.7° vs. -15.7° ± 5.1° in Group 1, P < 0.001). There were no significant differences in sacral slope (36.5° ± 7.3° in Group 1 vs. 36.8° ± 6.7° in Group 2, P = 0.67) and pelvic incidence (46.5° ± 7.7° in Group 1 vs. 48.2° ± 8.5° in Group 2, P = 0.06). There was no significant difference in the measurement of distance from C7 plumb to the postero-superior endplate of S1 (-0.7 ± 2.4 cm in Group 1 vs. -0.3 ± 2.7 cm in Group 2, P = 0.197). However, the distance from T12 plumb to the postero-superior endplate of S1 (-0.7 ± 1.7 cm in Group 1 vs. -2.2 ± 1.7 cm in Group 2, P < 0.001) demonstrated a significant difference., Conclusion: The old men group demonstrated a significant increase in thoracic kyphosis, thoracolumbar kyphosis, total and lower lumbar lordosis, a higher ratio of lower to total lumbar lordosis, and a longer distance from T12 plumb to the postero-superior endplate of S1 without changes in sacral slope and global sagittal balance.

Study Design: Prospective clinical series., Objective: To determine how many thoracic scoliotic pedicles have cancellous versus cortical versus absent channels., Summary of Background Data: Although morphologic evaluations of thoracic pedicles have been well reported, the results do not practically reflect clinical findings during actual pedicle screw placement. We propose a novel pedicle channel classification describing the osseous anatomy encountered during pedicle probe insertion., Methods: We noted 4 pedicle types in 53 consecutive scoliosis patients. Type A: pedicle probe smoothly inserted without difficulty; the morphology is described as a "Large Cancellous Channel." Type B: pedicle probe inserted snugly with increased force; described as a "Small Cancellous Channel." Type C: pedicle probe cannot be manually pushed but must be tapped with a mallet down the pedicle into the body; described as a "Cortical Channel." Type D: pedicle probe cannot locate a channel thus necessitating a "juxtapedicular" screw position; described as a "Slit/Absent Channel." The average age at time of surgery was 23.4 ± 16.7 years. Diagnoses included idiopathic scoliosis (n = 38) and syndromic scoliosis (n = 15). The average main thoracic Cobb angle was 73° ± 26°. Evaluation of pedicle morphology of the 4 types was also performed in 21 consecutive cases of adolescent idiopathic scoliosis using preoperative computed tomography images., Results: A total of 1021 pedicles with screws placed were evaluated. The average percent per type was as follows: 61.0% type A; 29.2% type B, 6.8% type C, and 3.0% type D. On the convexity, 98.2% of pedicles were type A or B versus 81.5% on the concavity (P < 0.05). There were significant differences between adolescent versus adult idiopathic scoliosis (P = 0.007), and syndromic scoliosis versus adult idiopathic scoliosis (P = 0.017) regarding pedicle morphologic proportions. There was a significant tendency toward a decrease in the proportion of type A pedicles, an increase in the proportion of type B pedicles as the Cobb angle increased (P < 0.0001). Evaluation based on 312 thoracic pedicles in 21 consecutive adolescent idiopathic scoliosis patients using preoperative computed tomography axial images confirmed assumptions of the 4 pedicle types., Conclusion: We propose a classification for pedicle channels describing the osseous anatomy encountered during pedicle probe insertion. Based on the classification, surprisingly, we found during surgery that 90% of thoracic pedicles had a cancellous channel, whereas 7% had a cortical channel and only 3% had an absent channel.

Study Design: A retrospective comparative study., Objective: To investigate the morphologic features of proximal vertebral fractures in adults following spinal deformity surgery using segmental pedicle screw instrumentation., Summary of Background Data: Fractures above pedicle screw constructs are a clinical problem that warrants further investigation for prevention and treatment., Methods: Ten adult patients (6 lumbar scoliosis, 4 degenerative sagittal imbalance) who underwent segmental spinal instrumented fusion were analyzed. Patients were divided into 2 groups according to the features of vertebral fracture: upper instrumented vertebral collapse + adjacent vertebral subluxation (SUB group: n = 5), and adjacent vertebral fracture (Fracture group: n = 5)., Results: Both groups demonstrated a high frequency of osteopenia and all patients in the SUB group had comorbidities before surgery. The SUB group demonstrated a shorter interval between initial surgery and the fracture (subluxation: 3 +/- 1.9 months; fracture: 33 +/- 25.3 months, P < 0.05), and hypokyphosis (T5-T12) in the thoracic region before surgery (SUB: 13 degrees +/- 6.4 degrees; fracture: 33 degrees +/- 15.6 degrees). Both groups demonstrated severe global sagittal imbalance (SUB: 151 +/- 62.8 mm; fracture: 94 +/- 102.2 mm), and hypolordosis (T12-S1) in the lumbar spine (SUB: -19 degrees +/- 24.4 degrees ; fracture: -33 degrees +/- 22.7 degrees) before surgery. Global sagittal imbalance in the SUB group was corrected to 8 +/- 17.4 mm immediately postoperative (P < 0.05), but increased to 64 +/- 19.9 mm after the junctional fractures (P < 0.05). The SUB group demonstrated a significantly higher wedging rate (SUB: 65% +/- 12.4%; fracture: 36% +/- 16.0%, P < 0.05) and greater local kyphosis (SUB: 42 degrees +/- 11.1 degrees; fracture: 17 degrees +/- 4.1 degrees, P < 0.05) after the fracture. Two of 5 patients in the SUB group demonstrated severe neurologic deficit from E to B after the fractures by a modified Frankel classification., Conclusion: Old age, osteopenia, preoperative comorbidities, and severe global sagittal imbalance were found to be frequent in patients with proximal junctional fracture. In addition, marked correction of sagittal malalignment might be considered as a risk factor of upper instrumented vertebra collapse followed by adjacent vertebral subluxation, which occurred in the first 6 months after corrective surgery with the potential for causing severe neurologic deficit because of the severe local kyphotic deformity.

Study Design: Retrospective study., Objective: To analyze the complications and patient satisfaction related to an anterior thoracolumbar approach in the treatment of adult spinal deformity., Summary of Background Data: There is no long-term follow-up data on the effects of an anterior thoracolumbar approach on adult spinal deformity patients., Methods: A specific questionnaire was used to evaluate long-term follow-up (average, 10.3 years; range, 5-20.6) of 62 adult patients who underwent spinal deformity surgery performed through an anterior thoracolumbar approach. Twenty-six patients had over 10 years follow-up and 36 were between 5 and 10 years follow-up. The questionnaire was composed of detailed scar-related subquestions for pain, appearance, bulging, daily life, and patient's personal opinion of surgery. Postoperative Oswestry Disability Index (scores) were also obtained., Results: The average age and number of anterior fusion levels were 47.9 (range, 20-74) and 5.6 (range, 2-12), respectively. Although 82.2% patients were satisfied with the results of their surgery, in general, many of the patients were dissatisfied with aspects related to their anterior incision. For the pain domain, 20 patients (32.3%, 6 with >10 years follow-up, 14 patients with 5 years follow-up) had pain over their thoracolumbar scar, which they rated as moderate to severe. Twenty-seven patients (43.5%) had bulging of their scar region, 4 were surgically indicated for repair, and 1 had multiple surgical repairs. Twelve patients (19.4%) felt they had a poor outcome related to the postoperative appearance of their anterior wound. Fifteen patients (24.2%) showed limitations in activities of daily living due to their anterior incision. Three patients with >10 years of follow-up and 4 with >5 years of follow-up felt they were getting worse. The average Oswestry Disability Index score was 25.0 +/- 16.3 (range, 0-52) postoperative., Conclusion: This is the first long-term (minimum 5 years) follow-up study focusing on patient outcomes after an anterior thoracolumbar approach for adult spinal deformity treatment. This approach appears to be associated with an appreciable high rate of postoperative pain (32.3%), bulging (43.5%), and functional disturbance (24.2%). Therefore, surgeons should use caution when recommending this approach to future adult spinal deformity patients.

Study Design: A retrospective review of pediatric kyphosis patients undergoing a spinal cord-level osteotomy for correction., Objective: To evaluate the prevalence, etiology, timing, and intervention related to loss of spinal cord monitoring data during surgical correction of pediatric kyphosis in the spinal cord region., Summary of Background Data: Although much has been written regarding the risks inherent to scoliosis surgery, there is less literature available regarding the neurologic outcomes of pediatric kyphosis surgery. As more surgeons contemplate posterior-only kyphosis correction with spinal cord-level osteotomies, the importance of maintaining spinal cord neurologic function is paramount., Methods: Forty-two patients with pediatric kyphosis undergoing a posterior-only spinal reconstruction with a spinal cord level osteotomy or posterior-based vertebral column resection performed were reviewed. Patients were categorized by diagnosis, type and incidence of osteotomies, and loss of neurogenic mixed-evoked potential (NMEP) data. Interventions required to regain data and postoperative neurologic outcomes were also reviewed., Results: Of the 42 patients, 9 (21.4%) demonstrated a complete loss of NMEP data sometime during surgery while concomitant somatosensory sensory-evoked potentials (SSEP) remained within acceptable limits of baseline values. All 9 patients had intraoperative intervention including: blood pressure elevation (n = 1), release of corrective forces (n = 2), blood pressure elevation and correction release (n = 3), malalignment/subluxation adjustment (n = 1), further bony decompression (n = 1), or restoration of anterior column height via a titanium cage along with further posterior decompression (n = 1). In all cases, SSEPs were unchanged and NMEPs returned varying from 8 to 20 minutes after loss, with all patients having a normal wake-up test intraoperatively and a normal neurologic examination after surgery., Conclusion: Intraoperative multimodality monitoring with some form of motor tract assessment is a fundamental component of kyphosis correction surgery in the spinal cord region in order to create a safer, optimal environment and to minimize neurologic deficit. The surgeon must be able to trust the information monitoring provides and act on it accordingly.

Study Design: A retrospective study., Objectives: To analyze radiographic and functional outcomes after posterior segmental spinal instrumentation and fusion (PSSIF) with and without an anterior apical release of the lumbar curve in adult scoliosis patients., Summary of Background Data: No comparison study on PSSIF of adult lumbar scoliosis with apical release versus without has been published., Methods: Forty-eight adult patients with lumbar scoliosis (average age at surgery 49.6 years, average follow-up 3.7 years) who underwent PSSIF were analyzed with respect to radiographic change, perioperative and postoperative complications, and Scoliosis Research Society (SRS) outcome scores. Twenty-three patients underwent an anterior apical release of the lumbar curve via a thoracoabdominal approach followed by PSSIF (Group I). The remaining 25 patients underwent a PSSIF of the lumbar curve followed by anterior column support at the lumbosacral region through an anterior paramedian retroperitoneal or posterior transforaminal approach (Group II)., Results: Before surgery, Group I showed a somewhat larger lumbar major Cobb angle (63.2 degrees vs. 55.9 degrees , P = 0.07), and both groups demonstrated significant differences in lumbar curve flexibility (26.9% vs. 37.2%, P = 0.02) and thoracolumbar kyphosis (27.0 degrees vs. 15.0 degrees , P = 0.03). After surgery, at the ultimate follow-up, there were no significant differences in major Cobb angle, C7 plumbline to the center sacral vertical line (P = 0.17), C7 plumbline to the posterior superior endplate of S1 (P = 0.44), and sagittal Cobb angles at the proximal junction (P = 0.57), T10-L2 (P = 0.24) and T12-S1 (P = 0.51). There were 4 pseudarthroses in Group I and one in Group II (P = 0.02). Postoperative total normalized SRS outcome scores at ultimate follow-up were significantly higher in Group II (69% vs. 79%, P = 0.01)., Conclusion: Posterior segmental spinal instrumentation and fusion without anterior apical release of lumbar curves in adult scoliosis demonstrated better total SRS outcome scores and no differences in radiographic parameters without differences in clinical complications. However, the use of BMP in some of these patients (44%) may have also contributed to these differences.

Study Design: Prospective clinical study of a retrospective database., Objective: To compare the prospective pulmonary function changes following anterior spinal instrumentation and fusion through an open thoracotomy with the same procedure through a thoracoabdominal approach at 2 years follow-up., Summary of Background Data: Open anterior spinal instrumentation and fusion for adolescent idiopathic scoliosis (AIS) has been known to decrease pulmonary function after surgery. However, the differential effect of an open thoracotomy versus thoracoabdominal approach on pulmonary function in AIS is unknown., Methods: Sixty-four AIS patients who underwent an anterior spinal instrumentation and fusion through an open thoracotomy (TC group) for a major main thoracic scoliosis were compared with 55 patients who underwent the same procedure through a thoracoabdominal approach (TA group) for a major thoracolumbar/lumbar (TL/L) scoliosis using pulmonary function tests assessing forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) before surgery and 2 years after surgery. The TC group was divided into 2 groups, TC group with thoracoplasty (1-5 ribs, n = 35) and TC group without thoracoplasty (n = 29)., Results: Preoperative and 2-year postoperative absolute FVC in the TC group averaged 3.05L and 2.74L, respectively (0.31L decrease, P < 0.0001) versus 3.27L and 3.21L, respectively (0.06L decrease, P = 0.15) in the TA group. The TC group demonstrated a significantly larger decrease in absolute FVC at 2 years postoperative (P < 0.0001). Preoperative and 2-year postoperative absolute FEV1 in the TC group averaged 2.56L and 2.35L, respectively (0.21L decrease, P < 0.0001) versus 2.82L and 2.81L, respectively (0.02L decrease, P = 0.67) in the TA group. The TC group demonstrated a significantly larger decrease in absolute FEV1 at 2 years postoperative (P = 0.001). TC patients with thoracoplasty (n = 35) demonstrated a similar average decrease (0.34L) of absolute FVC at 2 years postoperative compared with those without thoracoplasty (0.26L, P = 0.49) and a similar average decrease of absolute FEV1 at 2 years postoperative (0.23L vs. 0.19L without thoracoplasty, P = 0.76)., Conclusion: An open thoracotomy approach for treating a main thoracic curve demonstrated a significant decrease in the absolute pulmonary function tests values at 2 years postoperative while the thoracoabdominal approach for treating a TL/L curve did not.

Study Design: : A retrospective study., Objective: : To evaluate the safety of free-hand pedicle screw placement during revision surgery at levels with a solid posterior fusion mass and/or identified pseudarthroses of the thoracic and lumbosacral spine., Summary of Background Data: : Placement of pedicle screws into previous fusion masses or pseudarthrosis levels of the spine is challenging because of the loss of anatomic landmarks. We are aware of no study focusing on screw placement without any type of radiographic or navigational assistance., Methods: : Thirty-seven patients underwent revision spinal surgery with posterior spinal instrumentation and fusion using 552 transpedicular screws by a single surgeon from 1994 to 2003. Among 552 screws, 184 were inserted into virgin levels, 60 were inserted into the vertebral body through previous screw holes, 208 were inserted into fusion masses, and 100 were inserted into pseudarthrosis levels. We used the quadrangulation method to gain pedicle access in a prior fusion mass after diligent exposure of any and all visible anatomic landmarks. All screws were analyzed using radiographs, intraoperative monitoring data, and clinical outcomes., Results: : There were 29 women and 8 men. The mean age of patients at the time of surgery was 38 + 6 years (range, 8-75 years). Six screws were removed intraoperatively according to the triggered electromyography criteria and 4 of them were repositioned after checking the integrity of the pedicle by a careful probing technique (1.09%). Six screws were removed after checking the intraoperative radiographs and 5 screws were misplaced, as noted, in postoperative radiographs (1.99%). Two patients underwent revision surgery at 3 days and 6 weeks after initial surgery, respectively, for root decompression at the osteotomy site although screw positions were correct., Conclusion: : The free-hand technique of thoracic and lumbosacral pedicle screw placement in revision spinal surgery is reliable and safe when using the quadrangulation method of gaining pedicle access in a prior fusion mass or at pseudarthrosis levels.

Study Design: Retrospective radiographic outcomes analysis., Objective: We had 3 hypotheses: 1) a longer fusion; 2) a more proximal instrumented vertebra, and 3) circumferential fusion versus posterior-only fusion would increase the likelihood of adjacent segment disease (ASD)., Summary of Background Data: The literature analyzing risk factors, prevalence, and presentation of patients with ASD is varied and without clear consensus., Methods: A total of 188 patients with minimum 5-year follow-up who had lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative disorders were included. Radiographic ASD was defined by: 1) development of spondylolisthesis >4 mm, 2) segmental kyphosis >10 degrees , 3) complete collapse of disc space, or 4) more than 2 grades worsening of Weiner classification. Clinical ASD was defined as 1) symptomatic spinal stenosis, 2) intractable back pain, or 3) subsequent sagittal or coronal imbalance., Results: Radiographic ASD occurred in 42.6% (80 of 188) of patients. Patients with radiographic ASD had worse Oswestry scores (20.3 vs. 12.5; P = 0.001) at ultimate follow-up than those without ASD. Clinical ASD developed in 30.3% (57 of 188) of patients. Clinical ASD manifested as spinal stenosis (n = 47), instability-type back pain (n = 5), and sagittal or coronal imbalance (n = 5). Age at surgery over 50 years and length of fusion were significant risk factors for the development of ASD in the lumbar spine. Fusion to L1-L3 proximally increased the risk of ASD when compared with L4 and L5. Circumferential fusion versus posterior fusion was not a significant factor in the development of ASD., Conclusion: Patients over the age of 50 were at higher risk of developing clinical ASD than those 50 years old or younger. Length of fusion was a significant risk factor in the development of ASD in the lumbar spine. Fusion up to L1-L3 increased the risk of ASD when compared with L4 and L5. Circumferential fusion, as opposed to posterolateral fusion, was not a statistically significant risk factor for the development of ASD.

The indications for thoracic pedicle screw fixation have expanded over the past decade. Thoracic pedicle screws are now being used in the treatment of degenerative, traumatic, neoplastic, congenital, and developmental disorders. The pedicles of T1, T2, and T3 are typically large and ovoid in shape and amenable to pedicle screw fixation in most instances. The placement of thoracic pedicle screws requires knowledge of the topographic and deep bony anatomy of the thoracic spine as well as an appreciation of the surrounding visceral structures at risk. With strict adherence to the surgical techniques of insertion, thoracic pedicle screw fixation is a safe and effective method of stabilization. It offers several advantages over other forms of fixation, especially in the upper thoracic spine where the options are limited.

Study Design: Retrospective study., Objective: To analyze the causes, prevalence of, and risk factors for sagittal thoracic decompensation in adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1., Summary of Background Data: To our knowledge, no studies on sagittal thoracic decompensation following long adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1 have been published., Methods: A clinical and radiographic assessment of 99 patients with adult lumbar spinal deformity (average age 56.7 years) who underwent long (> or = 4 vertebrae; range 4-10/average 6.7) spinal instrumentation and fusion (from lower thoracic or upper lumbar spine to L5 or S1) at a single institution between 1985 and 2003 with a minimum 2-year follow-up (average 4.5 years) was performed. We defined sagittal thoracic decompensation as a progressive kyphotic deformity of the thoracic spine without pseudarthrosis after a long lumbar fusion, which subsequently resulted in a C7 plumb relative to the posterior aspect of the L5-S1 disc > or = 8 cm., Results: The prevalence of sagittal thoracic decompensation after long adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1 was 23% (23/99 cases). The etiologies were 14 acute sharp angular kyphoses and 9 long sweeping kyphoses above the instrumented fusion. Of the 14 sharp angular kyphoses, 10 occurred from severe disc degeneration and 4 were caused by compression fractures at the uppermost instrumented vertebra., Conclusion: Risk factors for sagittal thoracic decompensation developing were sagittal imbalance at 8 weeks postoperatively (> or = 5 cm), smaller lumbar lordosis compared with thoracic kyphosis (< 10 degrees) at 8 weeks postoperatively, preoperative sagittal imbalance (> or = 5 cm), age at surgery (older than 55 years), and associated comorbidities. Sagittal thoracic decompensation adversely affected Scoliosis Research Society 24 outcomes scores.

Study Design: A retrospective review of adolescent idiopathic scoliosis (AIS) patients with major thoracic-compensatory lumbar C modifier curves treated with a selective posterior fusion using an all-hook construct versus pedicle screw construct., Objectives: To compare the clinical and radiographic results of selective posterior thoracic fusion using hooks versus pedicle screws in patients with major thoracic-compensatory lumbar C modifier AIS curves., Summary of Background Data: Although spontaneous lumbar curve correction often occurs following a selective thoracic spinal fusion, there are few reports that focus on selective posterior thoracic spinal fusion in the presence of a lumbar C modifier curve., Methods: Sixty-six consecutive patients with major thoracic-compensatory lumbar C modifier AIS curves underwent selective posterior thoracic fusion to T12 or L1 at a single institution (1987-2001). Hooks were used for instrumentation in 32 patients and pedicle screws were used in 34 patients. Patients were evaluated at a minimum 2-year follow-up. To test for differences between groups analysis of covariance (ANCOVA) was used., Results: There was no statistical difference between the preoperative thoracic and lumbar Cobb values for the hook group versus the pedicle screw group. The amount of correction obtained surgically of the thoracic Cobb and the amount of spontaneous lumbar Cobb correction were significantly greater in the pedicle screw group (P < 0.001). The incidence of postoperative coronal decompensation, with a greater than 20 mm shift to the left of the C7 plumbline, was higher in the hook group (13 patients) as compared with the pedicle screw Group 4 patients (P < 0.005). There were no complications or reoperations in either group., Conclusion: Selective thoracic fusion of main thoracic-compensatory lumbar C modifier AIS curves with pedicle screws allowed for better thoracic correction and less postoperative coronal decompensation than seen with hooks.

Study Design: A retrospective review of adolescents with main thoracic scoliotic curves surgically treated with either anterior release and posterior fusion or posterior fusion only., Objectives: To compare the radiographic and clinical outcomes of two surgical treatments: anterior-posterior spinal fusion (APSF) versus posterior spinal fusion (PSF) alone in patients with large 70 degrees to 100 degrees thoracic adolescent idiopathic scoliosis (AIS) curves., Summary of Background Data: Surgical treatment of thoracic AIS curves between 70 degrees and 100 degrees often consists of anterior and posterior fusion to improve the coronal correction and fusion rate, with the anterior release and fusion performed through either an open thoracotomy or by video-assisted thoracoscopy., Methods: All patients (n = 84) with main thoracic major AIS curves between 70 degrees and 100 degrees who underwent spinal fusion (APSF or PSF) at one center between 1987 and 2001 were included for analysis. The minimum follow-up was 2 years after surgery (mean, 4.5 years; range, 2.0-10.2 years). The mean age of patients was 13.8 years (range, 10.7-18.2 years), with 66 females and 18 males. Multiple radiographic measures were assessed. The primary and secondary statistical analyses performed were nonparametric analyses, using the Wilcoxon-Mann-Whitney tests for the primary analysis of APSF and PSF groups. The PSF subgroup analysis was performed with the Kruskal-Wallis test., Results: There were 22 patients in the APSF (open ASF in 18, and video-assisted thoracoscopy in 4) group and 62 patients in the PSF group. There were no statistically significant differences between the groups for gender, age, number of levels fused, Cobb measurement of preoperative coronal or sagittal thoracic curve magnitude, or coronal curve flexibility. The APSF group, when compared with the PSF group, had greater intraoperative correction of the coronal curve (48.3 degrees vs. 38.7 degrees, P = 0.0087) as well as final overall correction (47.2 degrees vs. 34.2 degrees, P = 0.0008). There were no significant differences seen in the sagittal alignment from T5-T12 (P = 0.3150) or the SRS outcomes data between the APSF and PSF only groups. Subanalysis of the PSF only group identified three distinct groups based on implants: hook-only constructs (n = 36), hybrid constructs of proximal hooks and distal pedicle screws (n = 15), and pedicle screw-only constructs (n = 11). Pedicle screw-only constructs corrected the coronal Cobb measurements more than the other two groups (47.5 degrees vs. hooks 37.7 degrees vs. hybrid 34.4 degrees , P = 0.0110), and to a similar extent as to the APSF group with no statistically significant difference in coronal correction (PSF, 47.5 degrees; APSF 48.3 degrees; P = 0.9014), nor any other parameter except for sagittal T5-T12 changes. There were no reoperations for implant failure/pseudarthroses in any of the patients., Conclusion: APSF of large thoracic curves allows greater coronal correction of thoracic curves between 70 degrees and 100 degrees, when compared with PSF alone using thoracic hook constructs, but not with the use of thoracic pedicle screw constructs. Scoliosis surgeons not using pedicle screw constructs need to decide if the modest improvement in coronal correction with a combined approach justifies its routine use in this patient population.

Study Design: A retrospective radiographic study., Objectives: To investigate which radiographic parameters correlate best to ultimate lowest instrumented vertebra (LIV) position and subjacent disc wedging following anterior spinal fusion (ASF) for thoracolumbar/lumbar (TL/L) adolescent idiopathic scoliosis (AIS)., Summary of Background Data: In an ASF of TL/L AIS, part of the operative goals are often to horizontalize and centralize the LIV, or potentially minimize subjacent disc wedging after surgery. To our knowledge, no study has investigated the specific radiographic parameters involved with obtaining these goals., Methods: Sixty-one patients with TL/L AIS were treated with an instrumented ASF with a minimum 2-year follow-up. Preoperative and postoperative radiographs were examined measuring various radiographic parameters of the curve itself along with the LIV and subjacent disc. Specific correlation of these parameters to the coronal disc angle immediately below the LIV (disc angle), LIV translation, and global coronal balance (C7-CSVL distance) at 2 years postoperative was analyzed, respectively., Results: The preoperative disc angle was 4.49 degrees +/- 5.48 and postoperative -5.85 degrees +/- 4.37. The change of the disc angle was significantly correlated to the LIV level relative to the preoperative lower end vertebra (LEV) (P < 0.006). Regressive analysis demonstrated the correlative parameters to the postoperative disc angle to be: preoperative upright disc angle; preoperative apex-LIV distance; and preoperative T12-LIV lordosis (P < 0.0001, r2 = 0.51). The correlative parameters to postoperative LIV translation were preoperative LIV translation and preoperative LIV rotation (P = 0.002, r2 = 0.2). The correlative parameter to postoperative C7-CSVL distance was only preoperative C7-CSVL distance (P < 0.0001, r2 = 0.3)., Conclusions: Postoperative subjacent disc wedging occurs most often when the preoperative subjacent disc is nearly parallel and when a shorter fusion excluding the LEV is performed. Preoperative LIV rotation significantly correlates to postoperative LIV translation. Surgeons should note these preoperative predictive factors to optimize radiographic results of the operative treatment of TL/L AIS.

Study Design: A retrospective study., Objective: To evaluate the safety of a free hand technique of pedicle screw placement in the thoracic spine at a single institution over a 10-year experience., Summary of Background Data: Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic., Materials and Methods: Three hundred ninety-four consecutive patients who underwent posterior stabilization utilizing 3204 transpedicular thoracic screws by 2 surgeons from 1992 to 2002 were analyzed. The mean age was 27 + 10 years (range 5 + 3-87 + 0 years) at the time of surgery. Etiologic diagnoses were: scoliosis in 273, kyphosis in 53, other spinal disease in 68. Pedicle screws were inserted using a free hand technique similar to that used in the lumbar spine in which anatomic landmarks and specific entry sites were used to guide the surgeon. A 2-mm tip pedicle probe was carefully advanced free hand down the pedicle into the body. Careful palpation of all bony borders (floor and four pedicle walls) was performed before and after tapping. Next, the screw was placed, followed by neurophysiologic (screw stimulation with rectus abdominus muscle recording) and radiographic (anteroposterior and lateral) confirmation. An independent spine surgeon using medical records and roentgenograms taken during treatment and follow-up reviewed all the patients., Results: The number of the screws inserted at each level were as follows (total n = 3204): T1, n = 13; T2, n = 60; T3, n = 192; T4, n = 275; T5, n = 279; T6, n = 240; T7, n = 230; T8, n = 253; T9, n = 259; T10, n = 341; T11, n = 488; T12, n = 572. Five hundred seventy-seven screws inserted into the deformed thoracic spine were randomly evaluated by thoracic computed tomography scan to assess for screw position. Thirty-six screws (6.2%) were inserted with moderate cortical perforation, which meant the central line of the pedicle screw was out of the outer cortex of the pedicle wall and included 10 screws (1.7%) that violated the medial wall. There were no screws (out of the entire study group of 3204) with any neurologic, vascular, or visceral complications with up to 10 years follow-up., Conclusions: The free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

Study Design: A prospective clinical study of thoracic pedicle screws monitored with triggered electromyographic testing., Objective: To evaluate the sensitivity of recording rectus abdominis triggered electromyographs to assess thoracic screw placement., Summary of Background Data: Triggered electromyographic testing from lower extremity myotomes has identified medially placed lumbar pedicle screws. Higher thresholds indicate intraosseous placement because of increased resistance to current flow. Lower thresholds correspond to compromised pedicles with potential for nerve impingement. No clinical study has correlated an identical technique with rectus muscle recordings, which are innervated from T6 to T12., Methods: A total of 677 thoracic screws were placed in 92 consecutive patients. Screws placed from T6 and T12 were evaluated using an ascending method of stimulation until a compound muscle action potential was obtained from the rectus abdominis. Threshold values were compared both in absolute terms and also in relation to other intrapatient values., Results: Screws were separated into three groups: Group A (n = 650 screws) had thresholds >6.0 mA and intraosseus placement. Group B (n = 21) had thresholds <6.0 mA but an intact medial pedicle border on reexamination and radiographic confirmation. Group C (n = 6) had thresholds <6.0 mA and medial wall perforations confirmed by tactile and/or visual inspection. Thus, 3.9% (27 of 677) of all screws had thresholds <6.0 mA. Only 22% (6 of 27) had medial perforation. Group B screws averaged a 54% decrease from the mean as compared with a 69% decrease for Group C screws (P = 0.0160). There were no postoperative neurologic deficits or radicular chest wall complaints., Conclusion: To assess thoracic pedicle screw placement, triggered electromyographic thresholds <6.0 mA, coupled with values 60-65% decreased from the mean of all other thresholds in a given patient, should alert the surgeon to suspect a medial pedicle wall breach.

Background Context: There are several reports regarding pathogeneses and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity surgery. However, the relationship between thoracolumbar muscle condition and PJK has not been investigated yet.Purpose: We aimed to elucidate the thoracolumbar muscle conditions on the incidence of PJK in adult patients with spinal deformity treated by long instrumented spinal fusion surgery stopping at thoracolumbar junction with a minimum 2-year follow-up (F/U).Study Design: This is a retrospective review of prospective database.Patient Sample: A total of 44 cases of patients having multilevel spinal instrumented fusion stopping at thoracolumbar junction for adult spinal deformity in two academic institutions from 2004 to 2012 were enrolled in this study.Outcome Measures: For clinical outcomes, the Scoliosis Research Society questionnaire-22r (SRS-22r) was used preoperatively and at ultimate F/U.Methods: Inclusion criteria were age >20 and minimum five vertebrae fused from T9 upper instrumented vertebra (UIV) to any lower instrumented vertebra. Radiographic assessment included pelvic parameters, Cobb measurements in the coronal-sagittal plane, and measurements of the thoracolumbar muscularity (cross-sectional area of muscle-vertebral body ratio×100) and fatty degeneration (signal intensity of muscle-subcutaneous fat ratio×100).Results: The prevalence of PJK was 38.6%. Age at surgery, gender, fusions extending to the sacrum, levels fused, combined anterior-posterior surgery, and a UIV level were not significantly different between PJK and non-PJK groups. Lower bone mineral density (BMD; T-score: -2.5 vs. -1.3, p=.003) and lower muscularity and higher fatty degeneration at the level of T10 to L2 (131.8 vs. 159.0, p<.01; 59.0 vs. 44.0, p<.001, respectively) were identified risk factors for PJK. Radiographic parameters demonstrated a higher postoperative lumbar lordosis (LL) change (43.8 vs. 29.3, p<.001) and a larger sagittal vertical axis (SVA) change with surgery (8.4 cm vs. 4.8 cm, p=.01) in those with PJK. Although SRS postop pain scores were inferior in PJK group (3.3 vs. 4.1, p<.05), there were no significant differences in the average scores between the groups (3.5 vs. 3.3, p<.05).Conclusions: Patients with PJK had lower thoracolumbar muscularity and higher fatty degeneration than patients without PJK before surgery. Our data suggest that osteoporosis, large corrections in LL and SVA with surgery, and lower muscularity and higher fatty degeneration at the thoracolumbar area can lead to PJK. [ABSTRACT FROM AUTHOR]

Objective : To improve pedicle screw placement accuracy with minimal radiation and low cost, we developed specially designed K-wire with a marker. To evaluate the accuracy of thoracolumbar pedicle screws placed using the novel guide-pin and portable X-rays. Methods : Observational cohort study with computerized tomography (CT) analysis of in vivo and in vitro pedicle screw placement. Postoperative CT scans of 183 titanium pedicle screws (85 lumbar and 98 thoracic from T1 to L5) placed into 2 cadavers and 18 patients were assessed. A specially designed guide-pin with a marker was inserted into the pedicle to identify the correct starting point (2 mm lateral to the center of the pedicle) and aiming point (center of the pedicle isthmus) in posteroanterior and lateral X-rays. After radiographically confirming the exact starting and aiming points desired, a gearshift was inserted into the pedicle from the starting point into the vertebral body through the center of pedicle isthmus. Results : Ninety-nine percent (181/183) of screws were contained within the pedicle (total 183 pedicle screws : 98 thoracic pedicle screws and 85 lumbar screws). Only two of 183 (1.0%) thoracic pedicle screws demonstrated breach (1 lateral in a patient and 1 medial in a cadaver specimen). None of the pedicle breaches were associated with neurologic or other clinical sequelae. Conclusion : A simple, specially designed guide-pin with portable X-rays can provide correct starting and aiming points and allows for accurate pedicle screw placement without preoperative CT scan and intraoperative fluoroscopic assistance. [ABSTRACT FROM AUTHOR]

The article cites a study which compares the postoperative proximal junctional change and revision prevalence as influenced by 3 different proximal levels after adult lumbar deformity instrumented fusion from the distal thoracic/upper lumbar spine (T9-L2) to L5 or S1. It reveals that three different proximal fusion levels did not demonstrate significant radiographic and clinical outcomes or revision prevalence after surgery.