Restoration of Sagittal Balance in Spinal Deformity Surgery

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

Clinical and Radiological Outcomes of Posterior Vertebral Column Resection for Severe Spinal Deformities

OBJECTIVE: The aim of this study was to investigate clinical and radiological outcomes of patients who underwent posterior vertebral column resection (PVCR) by a single neurosurgeon in a single institution.METHODS: Thirty-four consecutive patients with severe spinal deformities who underwent PVCR between 2010 and 2016 were enrolled. The radiographic measurements included a kyphotic angle of PVCR levels (VCR angle), sagittal vertical axis (SVA), thoracic kyphosis, lumbar lordosis (LL), and spinopelvic parameters. The data of surgical time, estimated blood loss, duration of hospital stay, complications, intraoperative neurophysiologic monitoring, and the Scoliosis Research Society (SRS)-22 questionnaire were collected using a retrospective review of medical records.RESULTS: The VCR angle, LL, and SVA values were significantly corrected after surgery. The VCR and LL angle were changed from the average of 38.4±32.1° and −22.1±39.1° to −1.7±29.4° (p < 0.001) and −46.3±23.8° (p=0.001), respectively. The SVA was significantly reduced from 103.6±88.5 mm to 22.0±46.3 mm (p=0.001). The clinical results using SRS-22 survey improved from 2.6±0.9 to 3.4±0.8 (p=0.033). There were no death and permanent neurological deficits after PVCR. However, complications occurred in 19 (55.9%) patients. Those patients experienced a total of 31 complications during- and after surgery. Sixteen reoperations were performed in twelve (35.3%) patients. The incidence of transient neurological deterioration was 5.9% (two out of 34 patients).CONCLUSION: Severe spinal deformities can be effectively corrected by PVCR. However, the PVCR technique should be utilized limitedly because surgery-related serious complications are relatively common.

Restoration of Sagittal Balance in Spinal Deformity Surgery

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

Clinical and Radiological Outcomes of Posterior Vertebral Column Resection for Severe Spinal Deformities

OBJECTIVE: The aim of this study was to investigate clinical and radiological outcomes of patients who underwent posterior vertebral column resection (PVCR) by a single neurosurgeon in a single institution. METHODS: Thirty-four consecutive patients with severe spinal deformities who underwent PVCR between 2010 and 2016 were enrolled. The radiographic measurements included a kyphotic angle of PVCR levels (VCR angle), sagittal vertical axis (SVA), thoracic kyphosis, lumbar lordosis (LL), and spinopelvic parameters. The data of surgical time, estimated blood loss, duration of hospital stay, complications, intraoperative neurophysiologic monitoring, and the Scoliosis Research Society (SRS)-22 questionnaire were collected using a retrospective review of medical records. RESULTS: The VCR angle, LL, and SVA values were significantly corrected after surgery. The VCR and LL angle were changed from the average of 38.4±32.1° and −22.1±39.1° to −1.7±29.4° (p < 0.001) and −46.3±23.8° (p=0.001), respectively. The SVA was significantly reduced from 103.6±88.5 mm to 22.0±46.3 mm (p=0.001). The clinical results using SRS-22 survey improved from 2.6±0.9 to 3.4±0.8 (p=0.033). There were no death and permanent neurological deficits after PVCR. However, complications occurred in 19 (55.9%) patients. Those patients experienced a total of 31 complications during- and after surgery. Sixteen reoperations were performed in twelve (35.3%) patients. The incidence of transient neurological deterioration was 5.9% (two out of 34 patients). CONCLUSION: Severe spinal deformities can be effectively corrected by PVCR. However, the PVCR technique should be utilized limitedly because surgery-related serious complications are relatively common.

A Comparative Analysis of Thoracic and Thoracolumbar Kyphosis between Young Men and Old Men / 대한정형외과학회잡지

PURPOSE: Little is known with respect to changes in the segmental thoracic and thoracolumbar kyphosis, which are major parameters influencing sagittal balance of the spine. The authors investigated the detailed segmental changes of those parameters by ageing. MATERIALS AND METHODS: A total of 326 normal asymptomatic males were divided into 2 groups; group 1 (mean age, 21.2+/-1.7; n=175) and group 2 (mean age, 64.1+/-6.4; n=151). After taking a standing sagittal radiograph, the sagittal spinal and pelvic parameters were measured. Thoracic and thoracolumbar kyphosis were classified according to segments A, C7 UEP (upper end vertebra)-T5 UEP; B, T5 UEP-T10 UEP; C, T10 UEP-T12 LEP (lower end vertebra); and D, (T12 LEP-L2 LEP), and analyzed between 2 groups, respectively. RESULTS: Thoracic kyphosis (21.1degrees+/-7.7degrees vs. 30.0degrees+/-8.8degrees, p<0.001), segment B (15.8degrees+/-6.1degrees vs. 18.1degrees+/-7.9degrees, p=0.003), and segment C (5.3degrees+/-5.1degrees vs. 11.8degrees+/-6.5degrees, p<0.001) were increased in group 2. In group 2 segment A showed decreased kyphosis (12.1degrees+/-6.4degrees vs. 9.8degrees+/-6.4degrees, p=0.001). In segment D no significant difference was observed between groups. CONCLUSION: Increased thoracic kyphosis was observed in the middle and lower thoracic regions. The authors provided important references of sagittal parameters to determine the expected ranges of kyphosis for a normal asymptomatic male of a given age.

Decision Making Algorithm for Adult Spinal Deformity Surgery

Adult spinal deformity (ASD) is one of the most challenging spinal disorders associated with broad range of clinical and radiological presentation. Correct selection of fusion levels in surgical planning for the management of adult spinal deformity is a complex task. Several classification systems and algorithms exist to assist surgeons in determining the appropriate levels to be instrumented. In this study, we describe our new simple decision making algorithm and selection of fusion level for ASD surgery in terms of adult idiopathic idiopathic scoliosis vs. degenerative scoliosis.

Pedicle Screw Placement in the Thoracolumbar Spine Using a Novel, Simple, Safe, and Effective Guide-Pin : A Computerized Tomography Analysis

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.

Adolescent Idiopathic Scoliosis Treatment by a Korean Neurosurgeon: The Changing Role for Neurosurgeons

OBJECTIVE: The purpose of this study was to evaluate radiographic/clinical outcomes of adolescent idiopathic scoliosis (AIS) patients treated by a Korean neurosurgeon. METHODS: Ten AIS patients were treated by a single neurosurgeon between January 2011 and September 2013 utilizing segmental instrumentation with pedicle screws. Basic demographic information, curve pattern by Lenke classification, number of levels treated, amount of correction achieved, radiographic/clinical outcomes [by Scolisis Resarch Society (SRS-22r) questionnaire] and complications were evaluated to determine the surgical results. Pulmonary function test was utilized to assess forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) before and after surgery. RESULTS: The average percentage of correction of the major structural curve was 73.6% (ranged from 64% to 81.5%). Preoperative and final postoperative absolute FVC averaged 3.03 L and 3.76 L (0.73 L increase, p=0.046), and absolute FEV1 averaged 2.63 L and 3.49 L (0.86 L increase, p=0.021). Preoperative and final postoperative average self-image and function scores of SRS-22r were, 2.6+/-0.5, 3.3+/-0.1, 4.0+/-0.5, and 4.6+/-0.0, respectively. There was a significant improvement of the self-image and function scores of SRS-22r questionnaires before and after surgery (p<0.05). There was no case of neurological deficit, infection and revision for screw malposition. One patient underwent a fusion extension surgery for shoulder asymmetry. CONCLUSION: Radiographic/clinical outcomes of AIS patients treated by a Korean neurosurgeon were acceptable. Fundamental understanding of pediatric spinal deformity is essential for the practice of AIS surgery.

Accuracy of Free Hand Pedicle Screw Installation in the Thoracic and Lumbar Spine by a Young Surgeon: An Analysis of the First Consecutive 306 Screws Using Computed Tomography

STUDY DESIGN: A retrospective cross-sectional study. PURPOSE: The purpose of this study is to evaluate the accuracy and safety of free-hand pedicle screw insertion performed by a young surgeon. OVERVIEW OF LITERATURE: Few articles exist regarding the safety of the free-hand technique without inspection by an experienced spine surgeon. METHODS: The index surgeon has performed spinal surgery for 2 years by himself. He performed fluoroscopy-assisted pedicle screw installation for his first year. Since then, he has used the free-hand technique. We retrospectively reviewed the records of all consecutive patients undergoing pedicle screw installation using the free-hand technique without fluoroscopy in the thoracic or lumbar spine by the index surgeon. Incidence and extent of cortical breach by misplaced pedicle screw was determined by a review of postoperative computed tomography (CT) images. RESULTS: A total of 36 patients received 306 free-hand placed pedicle screws in the thoracic or lumbar spine. A total of 12 screws (3.9%) were identified as breaching the pedicle in 9 patients. Upper thoracic spine was the most frequent location of screw breach (10.8%). Lateral breach (2.3%) was more frequent than any other direction. Screw breach on the right side (9 patients) was more common than that on the left side (3 patients) (p<0.01). CONCLUSIONS: An analysis by CT scan shows that young spine surgeons who have trained under the supervision of an experienced surgeon can safely place free-hand pedicle screws with an acceptable breach rate through repetitive confirmatory steps.

Technical Report of Free Hand Pedicle Screw Placement using the Entry Points with Junction of Proximal Edge of Transverse Process and Lamina in Lumbar Spine: Analysis of 2601 Consecutive Screws

OBJECTIVE: A variety of different pedicle screws entry point techniques are used for the lumbar pedicle screws placement. This study reported Kim's entry point of lumbar pedicle screws with free hand technique and the accuracy of this technique. METHODS: We retrospectively reviewed the 584 cases with free hand placed lumbar pedicle screw placement. The diagnosis included 491 cases with degenerative spine, 59 cases with trauma, 29 cases with metastatic disease, and 5 cases with scoliosis. A total of 2601 lumbar pedicle screws were placed, and the entry points of lumbar pedicle screws were the junction of proximal edge of transverse process and lamina. Incidence and extent of cortical breach by misplaced pedicle screw was determined by review of intra-operative and post-operative radiographs and/or computed tomography. RESULTS: Among the total 2601 lumbar free hand placed pedicle screws, 114 screws (4.4%) in 79 patients (13.5%) were repositioned screws with suspected screw malposition during operation, and 37 screws (1.4%) in 31 patients (5.3%) were identified as moderate to severe breaching the pedicle after post-operative imaging studies. Among the patient with malpositioned screws, 3 patients showed nerve irritation sign of the lesion, and 2 cases were symptom improved after nerve block and conservative management, and 1 case was removed the screw after the failure of the treatment. CONCLUSION: Free hand pedicle screw placement based on external landmark with the junction of proximal edge of transverse process and lamina showed acceptable safety and accuracy and avoidance of radiation exposure.

Free Hand Pedicle Screw Placement in the Thoracic Spine without Any Radiographic Guidance : Technical Note, a Cadaveric Study

Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic deficit. Methods to aid the surgeon in appropriate screw placement have included the use of intraoperative fluoroscopy and/or radiography as well as image-guided techniques. We describe our technique for free hand pedicle screw placement in the thoracic spine without any radiographic guidance and present the results of pedicle screw placement analyzed by computed tomographic scan in two human cadavers. This 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.

Changes in Sagittal Spinopelvic Parameters according to Pelvic Incidence in Asymptomatic Old Korean Men

STUDY DESIGN: A radiographic study of normal subjects. OBJECTIVES: To analyze sagittal spinal parameters according to the size of pelvic incidence (PI). SUMMARY OF LITERATURE REVIEW: There has been no previous study about the classification of spinopelvic parameters that has used a large cohort of asymptomatic older men with the same ethnic background as those in the current study. MATERIALS AND METHODS: We examined 160 males aged over 50 without disease, trauma, or history of operation on spine or lower extremities. Sagittal standing radiographs of the whole spine on 36-inch film were taken. Group 1 (n=30) had a PI of less than 40degrees. Group 2 (n=71) had PI between 40degrees and 50degrees, and group 3 (n=59) had a PI greater than 50degrees. Thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis, the vertebral slope of T12, sacral slope, and pelvic incidence were measured. The distances from the plumb line of C7, T12, and the lumbar apex to the posterosuperior corner of the sacrum were also measured. RESULTS: Subjects' average age was 64.1(53~83).Lumbar lordosis, sacral slope and pelvic tilt were all significantly increased in group 3. Thoracic kyphosis and the vertebral slope of T12 were not different between groups. The distances from the plumb line of C7, T12, and the lumbar apex to the posterosuperior corner of the sacrum were significantly translated anteriorly in group 3. CONCLUSIONS: Group 3, who had the largest PI, demonstrated the largest lumbar lordosis and the most forward transition of trunk. However there were no differences in thoracic kyphosis and the vertebral slope of T12 among the three groups.

History of Spinal Deformity Surgery Part I: The Pre-modern Era

Spinal deformity is one of the oldest known diseases that date back thousands of years in human history. It appears in fairy tales and mythologies in association with evil as its dramatic appearance in patients suffering from the disease easily lent itself to be thought of as a form of divine retribution. The history of spinal deformity dates back to prehistoric times. The early attempts to treat patients suffering from this disease started from Hippocrates age. Side traction or axial traction and cast immobilization were the only possible option prior to the discovery of anesthesia. The first surgical attempts to correct scoliosis occurred in the mid 19th century with percutaneous myotomies of the vertebral musculature followed by postoperative bracing, which outcomes were very quite horrifying. Hibbs' fusion operation had become a realistic treatment option to halt the progression of deformity in the early 20th century. Harrington's introduction of the internal fixation device to treat paralytic scoliosis in 1960's started revolution on deformity correction surgery. Luque developed a segmental spinal using sublaminar wiring technique in 1976 and Cotrel developed Cotrel-Dubousset (CD) instrumentation, which was a posterior segmental instrumentation system that used pedicle and laminar hooks on either thoracic or lumbar spine and pedicle screws on the lumbar spine.

History of Spinal Deformity Surgery Part II: The Modern Era

Following Dwyer introduction of anterior spinal instrumented fusion surgery, Zielke, Moss-Miami, and Kaneda had made a significant progression on anterior spinal instrumented fusion which allowed excellent correction without significant loss of correction or implant failure. King and Moe deveoped classification of thoracic major curve following Harrington rod intrumentation. King classification presented a stable vertebra concept and selective fusion concept. Surgical classification of Adolescent Idiopathic Scoliosis (AIS) developed by Harms study group provided a more sophisticated two dimensional understanding of curve nature. Surgical intervention of adult scoliosis and sagittal imbalance is still challenging and evolving. Several evidences such as sacropelvic fixation and bone morphogenetic protein helped us to deal with adult deformity. The surgical decision making on spinal deformity surgery is still yet evolving.

A Mid-Term Follow-Up Result of Spinopelvic Fixation Using Iliac Screws for Lumbosacral Fusion

OBJECTIVE: Iliac screw fixation has been used to prevent premature loosening of sacral fixation and to provide more rigid fixation of the sacropelvic unit. We describe our technique for iliac screw placement and review our experience with this technique. METHODS: Thirteen consecutive patients who underwent spinopelvic fixation using iliac screws were enrolled. The indications for spinopelvic fixation included long segment fusions for spinal deformity and post-operative flat-back syndrome, symptomatic pseudoarthrosis of previous lumbosacral fusions, high-grade lumbosacral spondylolisthesis, lumbosacral tumors, and sacral fractures. Radiographic outcomes were assessed using plain radiographs, and computed tomographic scans. Clinical outcomes were assessed using the Oswestry Disability Index (ODI) and questionnaire about buttock pain. RESULTS: The median follow-up period was 33 months (range, 13-54 months). Radiographic fusion across the lumbosacral junction was obtained in all 13 patients. The average pre- and post-operative ODI scores were 40.0 and 17.5, respectively. The questionnaire for buttock pain revealed the following: 9 patients (69%) perceived improvement; 3 patients (23%) reported no change; and 1 patient (7.6%) had aggravation of pain. Two patients complained of prominence of the iliac hardware. The complications included one violation of the greater sciatic notch and one deep wound infection. CONCLUSION: Iliac screw fixation is a safe and valuable technique that provides added structural support to S1 screws in long-segment spinal fusions. Iliac screw fixation is an extensive surgical procedure with potential complications, but high success rates can be achieved when it is performed systematically and in appropriately selected patients.