Relationship between Sagittal Alignment and Anterior Bony Resorption of Cervical Vertebral Body in Patients with Ankylosing Spondylitis

Methods@#This retrospective study included 238 patients with AS who underwent surgical correction for thoracolumbar kyphosis. Of these, 80 patients with complete subaxial ankylosis were selected and divided into two groups: groups 1 (consisting of 28 patients with anterior bony resorption) and 2 (consisting of 52 patients without anterior resorption). Cervical sagittal parameters were analyzed and compared between the two groups. @*Results@#The average lateral diameter measured in patients with C5 anterior resorption was 84.2%±7.8% (62.4%–96.8%). Cervical lordosis was 8.7°±13.4° and 10.9°±11.5° in groups 1 and 2 (p=0.556), respectively. No significant differences were noted between the two groups on spinopelvic alignment in the T1 slope (52.2°±11.1° and 53.3°±9.9° in groups 1 and 2, respectively; p=0.742), C2–C7 sagittal vertical axis (SVA; 6.2±1.7 cm and 6.2±1.8 cm in groups 1 and 2, respectively; p=0.978), C7 SVA (14.3±4.9 cm and 14.6±6.2 cm in groups 1 and 2, respectively; p=0.823), or T1 pelvic angle (27.1°±8.9° and 31.6°±11.2° in groups 1 and 2, respectively; p=0.382). Correlation analyses were significant between the extent of anterior resorption and sagittal parameters, C2–C7 lordosis (R2=−0.428, p=0.021), and T1–T4 kyphosis (R2=−0.375, p=0.045). @*Conclusions@#Anterior bony resorption could develop by stress concentration. However, the development was not related to the sagittal alignment. The particular segments involved in developing anterior resorption varied, possibly because of their dependence on the preceding pattern of ankylosis.

Outcomes of Non-Operative Management for Pseudarthrosis after Pedicle Subtraction Osteotomies at Minimum 5 Years Follow-Up

OBJECTIVE: Minimal data exist regarding non-operative management of suspected pseudarthrosis after pedicle subtraction osteotomy (PSO). This study reports radiographic and clinical outcomes of non-operative management for post-PSO pseudarthrosis at a minimum 5 years post-detection.METHODS: Nineteen consecutive patients with implant breakage indicating probable pseudarthrosis after PSO surgery (13 women/six men; mean age at surgery, 58 years) without severe pain and disability were treated with non-operative management (mean follow-up, 5.8 years; range, 5–10 years). Non-operative management included medication, intermittent brace wearing and avoidance of excessive back strain. Radiographic and clinical outcomes analysis was performed.RESULTS: Sagittal vertical axis (SVA), proximal junctional angle, thoracic kyphosis achieved by a PSO were maintained after detection of pseudarthrosis through ultimate follow-up. Lumbar lordosis and PSO angle decreased at final follow-up. There was no significant change in Oswestry Disability Index (ODI) scores and Scoliosis Research Society (SRS) total score, or subscales of pain, self-image, function, satisfaction and mental health between detection of pseudarthrosis and ultimate follow-up. SVA greater than 11 cm showed poorer ODI and SRS total score, as well as the pain, self-image, and function subscales (p<0.05).CONCLUSION: Non-operative management of implant failure of probable pseudarthrosis after PSO offers acceptable outcomes even at 5 years after detection of implant breakage, provided SVA is maintained. As SVA increased, outcome scores decreased in this patient population.

Outcomes of Non-Operative Management for Pseudarthrosis after Pedicle Subtraction Osteotomies at Minimum 5 Years Follow-Up

OBJECTIVE: Minimal data exist regarding non-operative management of suspected pseudarthrosis after pedicle subtraction osteotomy (PSO). This study reports radiographic and clinical outcomes of non-operative management for post-PSO pseudarthrosis at a minimum 5 years post-detection. METHODS: Nineteen consecutive patients with implant breakage indicating probable pseudarthrosis after PSO surgery (13 women/six men; mean age at surgery, 58 years) without severe pain and disability were treated with non-operative management (mean follow-up, 5.8 years; range, 5–10 years). Non-operative management included medication, intermittent brace wearing and avoidance of excessive back strain. Radiographic and clinical outcomes analysis was performed. RESULTS: Sagittal vertical axis (SVA), proximal junctional angle, thoracic kyphosis achieved by a PSO were maintained after detection of pseudarthrosis through ultimate follow-up. Lumbar lordosis and PSO angle decreased at final follow-up. There was no significant change in Oswestry Disability Index (ODI) scores and Scoliosis Research Society (SRS) total score, or subscales of pain, self-image, function, satisfaction and mental health between detection of pseudarthrosis and ultimate follow-up. SVA greater than 11 cm showed poorer ODI and SRS total score, as well as the pain, self-image, and function subscales (p<0.05). CONCLUSION: Non-operative management of implant failure of probable pseudarthrosis after PSO offers acceptable outcomes even at 5 years after detection of implant breakage, provided SVA is maintained. As SVA increased, outcome scores decreased in this patient population.

Surgical Correction of Adult Spinal Deformity / 대한정형외과학회잡지

Surgical correction of adult spinal deformity is a challenge, and is physically and mentally demanding for spinal surgeons. For satisfactory surgical outcomes, proper patient selection is fundamental and preoperative detailed physical examination, intra-operative neuromonitoring, and collaboration with anesthesiology or internal medicine department are critical for prevention of peri-operative complications associated with surgical treatments. A posterior-only or anterior-posterior combined approach can be used. Considering the patients' hemodynamic status or long-time anesthesia, surgeons can decide whether to operate by stage or one stage. Deformity correction can be performed using spinal osteotomy or anterior interbody fusion. Decision regarding correction method depends on the patient's condition and correction degree or level. In this review, the authors try to help in decision making with regard to deformity correction methods for ideal surgical technique, correction angle, fusion length etc. in reference to previous literature.

Single-Stage Posterior Subtotal Corpectomy and Circumferential Reconstruction for the Treatment of Unstable Thoracolumbar Burst Fractures

OBJECTIVE: To illustrate the technique of single-stage posterior subtotal corpectomy and circumferential reconstruction for the treatment of unstable thoracolumbar burst fractures and to evaluate the radiographical and clinical outcomes of patients treated using this technique. METHODS: 16 consecutive patients with unstable thoracolumbar burst fractures were treated with single-stage posterior subtotal corpectomy and circumferential reconstruction. The mean patient age was 54.8 years. The mean follower up period was 25 months. Five patients suffered from T12 fractures, 10 from L1, 1 from L2. The segmental kyphosis, neurologic status, visual analogue scale for back pain was evaluated before surgery and at follow up. RESULTS: The segmental kyphotic angle improved from 18.5 degrees before surgery to -9.2 degrees at the last follow up. The mean correction angle was 28.9 degrees. The mean surgical time was 255 minutes, and a mean intraoperative blood loss was 1073 mL. Intraoperative complications included two dural tears, and a superficial wound infection. There were no other severe complications. The mean visual analog scale of back pain decreased from a mean value of 6.6 to 2 at the last follow up. CONCLUSION: The single-stage posterior subtotal corpectomy and circumferential reconstruction achieved satisfactory kyphosis correction with direct visualization of the circumferentially decompressed spinal cord, as well as good fusion with less blood loss and complications. It is a safe and reliable surgical treatment option for unstable thoracolumbar burst fractures.

Restoration of Lumbar Lordosis in Flat Back Deformity: Optimal Degree of Correction

STUDY DESIGN: A retrospective comparative study. PURPOSE: To provide an ideal correction angle of lumbar lordosis (LL) in degenerative flat back deformity. OVERVIEW OF LITERATURE: The degree of correction in degenerative flat back in relation to pelvic incidence (PI) remains controversial. METHODS: Forty-nine patients with flat back deformity who underwent corrective surgery were enrolled. Posterior-anterior-posterior sequential operation was performed. Mean age and mean follow-up period was 65.6 years and 24.2 months, respectively. We divided the patients into two groups based on immediate postoperative radiographs-optimal correction (OC) group (PI-9degrees or =55degrees). Radiological and clinical results were analyzed. RESULTS: Patients in OC group had significantly less correction loss and maintained normal sagittal alignment (sagittal vertical axis<5 cm), as compared to patients in UC group (p<0.05). LL of low PI group significantly maintained within 9degrees better than high PI group (p<0.05). Oswestry disability index (ODI) significantly decreased at last follow-up, as compared to preoperative state. However, there was no significant difference in last follow-up ODI between the groups. CONCLUSIONS: In flat back deformity, correction of LL to within 9degrees of PI will result in better sagittal balance. Thus, we recommend sufficient LL to prevent correction loss, especially in patients with high PI.

Three Different Methods in Deformity Correction of Degenerative Flat Back: A Single Surgeon's Experience with 64 Consecutive Cases

STUDY DESIGN: Retrospective study. PURPOSE: To evaluate the radiological and clinical results of three different methods in the deformity correction of a degenerative flat back. OVERVIEW OF LITERATURE: There are no comparative studies about different procedures in the treatment of degenerative flat back. METHODS: Sixty-four patients who consecutively underwent corrective surgery for degenerative flat back were reviewed. The operations were performed by three different methods: posterior-only (group P, n=20), one-stage anterior-posterior (group AP, n=12), and two-stage anterior-posterior with iliac screw fixation (group AP-I, n=32). Medical and surgical complications were examined and radiological and clinical results were compared. RESULTS: The majority of medical and surgical complications were found in group AP (5/12) and group P (7/20). The sagittal vertical axes were within normal range immediately postoperatively in all groups, but only group AP-I showed normal sagittal alignment at the final follow-up. Postoperative lumbar lordosis was also significantly higher in group AP-I than in group P or group AP and the finding did not change through the last follow-up. The Oswestry disability index was significantly lower in groups AP and AP-I than in group P at the final follow-up. Meanwhile, the operating time was the longest in group AP-I, and total amount of blood loss was larger in group AP-I and group AP than in group P. CONCLUSIONS: Anterior-posterior correction showed better clinical results than posterior-only correction. Two-staged anterior-posterior correction with iliac screw fixation showed better radiological results than posterior-only or one-staged anterior-posterior correction. Two-staged anterior-posterior correction with iliac screw fixation also showed a lower complication rate than one-staged anterior-posterior correction.

Results of Corrective Osteotomy and Treatment Strategy for Ankylosing Spondylitis with Kyphotic Deformity

BACKGROUND: To report the radiological and clinical results after corrective osteotomy in ankylosing spondylitis patients. Furthermore, this study intended to classify the types of deformity and to suggest appropriate surgical treatment options. METHODS: We retrospectively analyzed ankylosing spondylitis patients who underwent corrective osteotomy between 1996 and 2009. The radiographic assessments included the sagittal vertical axis (SVA), spinopelvic alignment parameters, correction angle, correction loss, type of deformity related to the location of the apex, and the craniocervical range of motion (CCROM). The clinical outcomes were assessed by the Oswestry Disability Index (ODI) scores. RESULTS: A total of 292 corrective osteotomies were performed in 248 patients with a mean follow-up of 40.1 months (range, 24 to 78 months). There were 183 cases of single pedicle subtraction osteotomy (PSO), 19 cases of multiple Smith-Petersen osteotomy (SPO), 17 cases of PSO + SPO, 14 cases of single SPO, six cases of posterior vertebral column resection (PVCR), five cases of PSO + partial pedicle subtraction osteotomy (PPSO), and four cases of PPSO. The mean correction angles were 31.9degrees +/- 11.7degrees with PSO, 14.3degrees +/- 8.4degrees with SPO, 38.3degrees +/- 12.7degrees with PVCR, and 19.3degrees +/- 7.1degrees with PPSO. The thoracolumbar type was the most common. The outcome analysis showed a significant improvement in the ODI score (p < 0.05). Statistical analysis revealed that the ODI score improvements correlated significantly with the postoperative SVA and CCROM (p < 0.05). There was no correlation between the clinical outcomes and spinopelvic parameters. There were 38 surgery-related complications in 25 patients (10.1%). CONCLUSIONS: Corrective osteotomy is an effective method for treating a fixed kyphotic deformity occurring in ankylosing spondylitis, resulting in satisfactory outcomes with acceptable complications. The CCROM and postoperative SVA were important factors in determining the outcome.

Surgical Correction in Patients with Lumbar Degenerative Kyphosis Who Had Low Bone Mineral Density: An Analysis of 40 Patients with a Minimum Follow-Up of Two Years

STUDY DESIGN: Retrospective study. PURPOSE: To investigate influence of bone mineral density (BMD) on the surgical correction of lumbar degenerative kyphosis (LDK). OVERVIEW OF LITERATURE: No studies so far have reported the influence of BMD on the surgical correction of LDK. METHODS: Forty LDK patients with more than 2 years follow-up were studied. Pelvic incidence (PI), pelvic tilt, sacral slope, sagittal vertical axis (SVA), lumbar lordosis (LL), and thoracic kyphosis were measured preoperatively, immediate postoperatively and at final follow-up. Adverse outcomes: proximal adjacent fractures, sagittal decompensation, pseudoarthrosis, and cage subsidence were documented. RESULTS: There were 37 females and 3 males. Average age was 65.1+/-4.5 years and mean follow-up was 34.2+/-16.7 months. 42.5% were Takemitsu type 3 curves, 27.5% type 2, 20.0% type 4 and 10.0% type 1. 37.5% had osteopenia, 40.0% osteoporosis and 22.5% had severe osteoporosis. SVA improved from 237.0+/-96.7 mm preoperatively to 45.3+/-41.8 mm postoperatively (p=0.000). LL improved from 10.5degrees+/-14.7degrees to -40.6degrees+/-10.9degrees postoperatively (p=0.000). At final follow-up SVA deteriorated to 89.8+/-72.2 mm and LL to 34.7degrees+/-15.8degrees (p=0.000). The association between late sagittal decompensation, pseudoarthrosis, or proximal adjacent fractures and osteoporosis was insignificant. The difference between immediate postoperative LL and PI (PIDiff) had a significant association with sagittal decompensation and pseudoarthrosis. CONCLUSIONS: Osteoporosis did not influence the degree of correction, late sagittal decompensation, proximal adjacent fractures, and pseudoarthrosis in LDK. PIDiff had a significant association with sagittal decompensation and pseudoarthrosis.

Efficacy and Safety of Sodium Hyaluronate with 1,4-Butanediol Diglycidyl Ether Compared to Sodium Carboxymethylcellulose in Preventing Adhesion Formation after Lumbar Discectomy

OBJECTIVE: Epidural injection of hyaluronic acid may prevent adhesion formation after spine surgery, but the compounds used to stabilize hyaluronidase could interfere with its anti-adhesion effects. The present study was conducted as a clinical trial to evaluate the efficacy and safety of an experimental medical gel in preventing adhesion formation. METHODS: This study was designed as a multicenter, randomized, double-blind, and comparative controlled clinical trial with an observation period of 6 weeks. Subjects were randomly assigned into two groups: group A with sodium hyaluronate + 1,4-butanediol diglycidyl ether (BDDE) and group B with sodium hyaluronate + sodium carboxymethylcellulose (CMC). Visual analogue scale (VAS) of back and leg pain and the Oswestry disability index (ODI) and scar score ratings were assessed after surgery. RESULTS: Mean scar grade was 2.37+/-1.13 in group A and 2.75+/-0.97 in group B, a statistically significant difference (p=0.012). VAS of back and leg pain and ODI scores decreased significantly from baseline to 3 and 6 weeks postoperatively in both groups (p0.3). The number of adverse reactions related to the anti-adhesion gels was not statistically different (p=0.569), but subsequent analysis of nervous adverse reactions showed group B was superior with a statistically difference (p=0.027). CONCLUSION: Sodium hyaluronate with BDDE demonstrated similar anti-adhesion properties to sodium hyaluronate with CMC. But, care should be used to nervous adverse reactions by using sodium hyaluronate with BDDE.

The Incidence and Management of Dural Tears and Cerebrospinal Fluid Leakage during Corrective Osteotomy for Ankylosing Spondylitis with Kyphotic Deformity

OBJECTIVE: To present the incidence and management of dural tears and cerebrospinal fluid leakage during corrective osteotomy [Pedicle Subtraction Osteotomy (PSO) or Smith-Petersen Osteotomy (SPO)] for ankylosing spondylitis with kyphotic deformity. METHODS: A retrospective study was performed for ankylosing spondylitis patients with fixed sagittal imbalance, who had undergone corrective osteotomy (PSO or SPO) at lumbar level. 87 patients were included in this study. 55 patients underwent PSO, 32 patients underwent SPO. The mean age of the patients at the time of surgery was 41.7 years (21-70 years). Of the 87 patients, 15 patients had intraoperative dural tears. RESULTS: The overall incidence of dural tears was 17.2%. The incidence of dural tears during PSO was 20.0%, SPO was 12.5%. There was significant difference in the incidence of dural tears based on surgical procedures (PSO vs. SPO) (p<0.05). The dural tears ranged in size from 12 to 221 mm2. A nine of 15 patients had the relatively small dural tears, underwent direct repair via watertight closure. The remaining 6 patients had the large dural tears, consequently direct repair was impossible. The large dural tears were repaired with an on-lay graft of muscle, fascia or fat harvested from the adjacent operation site. All patients had a successful repair with no patient requiring reoperation for the cerebrospinal fluid leak. CONCLUSION: The overall incidence of dural tears during PSO or SPO for ankylosing spondylitis with kyphotic deformity was 17.2%. The risk factor of dural tears was complexity of surgery. All dural tears were repaired primarily using direct suture, muscle, fascia or fat graft.

The Impact of Lumbar Lordosis on the Adjacent Segment Disease after Posterior Lumbar Interbody Fusion

STUDY DESIGN: A retrospective study. OBJECTIVES: We analyzed the risk factors and relevance of lumbar lordosis on the incidence of adjacent segment disease after posterior lumbar interbody fusion. SUMMARY OF LITERATURE REVIEW: Maintaining lumbar sagittal balance is important for decreasing the incidence of adjacent segment disease after posterior lumbar interbody fusion. MATERIALS AND METHODS: Among the patients who had undergone posterior lumbar interbody fusion of 1 or 2 levels between August 2001 and October 2008, we analyzed 153 patients who were available for at least three years of follow-up; among the subjects, 115 were males and 38 were females. Mean age among the patients at the time of initial surgery was 60.3 (range, 41-82) and mean followup period was 5.6 years (range, 3-11). The causative diseases were spinal stenosis in 78 cases, degenerative spondylolisthesis in 51 cases, isthmic spondylolisthesis in 23 cases, and degenerative disc disease in 1 case. At last follow-up, there were 52 cases (33.9%) of adjacent segment disease. Among them were found 21 cases (40.4%) of disc degeneration, 17 cases (32.7%) of instability, and 14 cases (26.9%) of simultaneous disc degeneration and instability. A total of 10 patients (6.5%) underwent a revision operation, and the mean period from initial to revision operation was 5.5 years (range, 3.1-10.3). We analyzed the correlation between risk factors of adjacent segment disease and the incidence of the disease depending on the gap between lumbar lordosis and pelvic incidence, and compared the clinical results of the 2 groups using modified Whitecloud classification. RESULTS: The incidence of adjacent segment disease was not statistically significant for patient age, sex, BMD, degree of obesity, causative disease, and the level of previous surgery. However, the incidence of adjacent segment disease was statistically higher in patients who had more than 9 degrees gap between lumbar lordosis and pelvic incidence (p=0.013). In our analysis of clinical results, 63.5% of the group of patients who developed adjacent segment disease and 80.2% of the group without adjacent segment disease had good or satisfactory results (p=0.031). CONCLUSIONS: Maintaining lumbar sagittal balance is important for decreasing the incidence of adjacent segment disease after posterior lumbar interbody fusion, and close observation is needed in patients with 9 or more degrees gap between lumbar lordosis and pelvic incidence.

The Insertion/Deletion Polymorphism of Angiotensin I Converting Enzyme Gene is Associated With Ossification of the Posterior Longitudinal Ligament in the Korean Population

OBJECTIVE: To determine whether ACE insertion/deletion (I/D) polymorphism is associated with the ossification of the posterior longitudinal ligament (OPLL) of the spine in the Korean population. METHODS: A case-control study was conducted to investigate the association between I/D polymorphism of the angiotensin I converting enzyme (peptidyl-dipeptidase A) 1 (ACE) gene and OPLL. The 95 OPLL patients and 274 control subjects were recruited. Polymerase chain reaction for the genotyping of ACE I/D polymorphism was performed. The difference between the OPLL patients and the control subjects was compared using the contingency chi2 test and the logistic regression analysis. For statistical analysis, SPSS, SNPStats, SNPAnalyzer, and Helixtree programs were used. RESULTS: The genotype and allele frequencies of ACE I/D polymorphism showed significant differences between the OPLL patients and the control subjects (genotype, p<0.001; allele, p=0.009). The frequencies of D/D genotype and D allele in the OPLL group were higher than those in the control group. In logistic regression analysis, ACE I/D polymorphism was associated with OPLL (dominant model; p=0.002; odd ratio, 2.20; 95% confidence interval, 1.33-3.65). CONCLUSION: These results suggest that the deletion polymorphism of the ACE gene may be a risk factor for the development of OPLL in the Korean population.

Association of COL2A1 Gene Polymorphism with Degenerative Lumbar Scoliosis

BACKGROUND: Degenerative lumbar scoliosis (DLS) progresses with aging after 50-60 years, and the genetic association of DLS remains largely unclear. In this study, the genetic association between collagen type II alpha 1 (COL2A1) gene and DLS was investigated. METHODS: COL2A1 gene polymorphism was investigated in DLS subjects compared to healthy controls to investigate the possibility of its association with COL2A1 gene. Based on a single nucleotide polymorphism (SNP) database, SNP (rs2276454) in COL2A1 were selected and genotyped using direct sequencing in 51 patients with DLS and 235 healthy controls. The SNP effects were analyzed using three models of codominant, dominant, and recessive. Logistic regression models were calculated for odds ratios (ORs) with 95% confidence intervals (CIs) and corresponding p-values, controlling age and gender as co-variables. RESULTS: SNP (rs2276454) in COL2A1 was significantly associated with the degenerative lumbar scoliosis in the codominant (OR, 1.90; 95% CI, 1.17 to 3.10; p = 0.008) and dominant models (OR, 3.58; 95% CI, 1.59 to 9.29; p = 0.001). CONCLUSIONS: The results suggest that COL2A1 is associated with the risk of DLS in Korean population.

Surgical Treatment of T1-2 Disc Herniation with T1 Radiculopathy: A Case Report with Review of the Literature

The prevalence of intervertebral disc herniation (IDH) of the thoracic spine is rare compared to the cervical or lumbar spine. In particular, IDH of the upper thoracic spine is extremely rare. We report the case of T1-2 IDH and its treatment, with a literature review. A 37-year-old male patient visited our hospital due to radiating pain at the left upper extremity and weakness of grip power. In cervical spine magnetic resonance images, T1-2 disc space showed herniated disc material and compressed T1 root was identified. Laminoforaminotomy was performed with a posterior approach. The radiating pain and weakness of grip power improved immediately after the surgery. Of patients who show radiating pain or numbness at the medial aspect of forearm, or weakness of intrinsic muscle of hand, can be suspected to have T1 radiculopathy. A detailed physical examination and a radiologic evaluation including this area should be required for the T1 radiculopathy.

Is It Real False Negative Finding in Motor Evoked Potential Monitoring during Corrective Surgery of Ankylosing Spondylitis? A Case Report

We performed L1 posterior vertebral columnar resection and posterior correction for Andersson's lesion and thoracolumbar kyphosis in an ankylosing spondylitis patient during motor evoked potential (MEP) monitoring. We checked MEP intra-operatively, whenever a dangerous procedure for neural elements was performed, and no abnormal findings were seen during surgery. After the operation, we examined neurologic function in the recovery room; the patient showed a progressive neurologic deficit and no response to MEP. After emergency neural exploration and decompression surgery, the neurologic deficit was recovered. We questioned whether to acknowledge the results of this case as a false negative. We think the possible reason for this result may be delayed development of paralysis. So, we recommend that MEP monitoring should be performed not only after important operative steps but also after all steps, including skin suturing, for final confirmation.

Association of Estrogen Receptor 2(ESR 2) Gene Polymorphisms with Ossification of the Posterior Longitudinal Ligament of the Spine

STUDY DESIGN: Genetic screening of the estrogen receptor 2 (ESR2) genes in patients with ossification of the posterior longitudinal ligament (OPLL). OBJECTIVE: We studied the relationships between ESR2 gene polymorphisms and OPLL to understand the pathophysiology of OPLL. SUMMARY OF LITERATURE REVIEW: The OPLL has a strong genetic component. Several familial surveys and human leukocyte antigen (HLA) haplotype studies reveal that genetic background is an important component in the occurrence of OPLL and a large number of gene analysis studies were utilized to clarify the susceptible gene for OPLL, including COL11A2, BMP-2, TNF-alpha, NPPS, leptin receptor, transforming growth factor (TGF)-beta, Retinoic X receptor, ER, IL-1, PTH, and VDR have been performed. MATERIALS AND METHOD: Genomic deoxyribonucleic acid (DNA) samples obtained from 164 patients (93 men and 71 women) with OPLL and 219 control subjects, without the disease (105 men and 114 women) were amplified by polymerase chain reaction, and polymorphism genotypes were determined by the restriction endonuclease digestion. The distribution of genotypes was compared between the patients with the disease and the control subjects. RESULTS: The polymorphism of ESR2 [rs1256049, exon6, Val328Val, p=0.018, odd ratio (OR)=2.41, 95 confidence interval (CI)=1.15-5.02 in the recessive model] only showed statistically significant association between the control and the OPLL groups. The rest SNPs of ESR2 did not show any significant differences between the control and the OPLL groups. CONCLUSIONS: Estrogen receptor 2 (ESR2) gene polymorphisms (rs 1256049) was associated with OPLL. In future studies, we will perform target SNP chip between OPLL and candidate gene.

Cervical Pedicle Screw Insertion Using the Technique with Direct Exposure of the Pedicle by Laminoforaminotomy

OBJECTIVE: To present the accuracy and safety of cervical pedicle screw insertion using the technique with direct exposure of the pedicle by laminoforaminotomy. METHODS: We retrospectively reviewed 12 consecutive patients. A total of 104 subaxial cervical pedicle screws in 12 patients had been inserted. We also assessed the clinical and radiological outcomes and analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1: 50% of screw diameter) on the postoperative vascular-enhanced computed tomography scans. Grade 2 and 3 were considered as incorrect position. RESULTS: The correct position was found in 95 screws (91.3%); grade 0-75 screws, grade 1-20 screws and the incorrect position in 9 screws (8.7%); grade 2-6 screws, grade 3-3 screws. There was no neurovascular complication related with cervical pedicle screw insertion. CONCLUSION: This technique (technique with direct exposure of the pedicle by laminoforaminotomy) could be considered relatively safe and easy method to insert cervical pedicle screw.

Comparative Study of the Clinical Outcomes of Unilateral Transforaminal Lumbar Interbody Fusion(TLIF) with Bilateral TLIF using Wiltse Approach and Conventional Approach

STUDY DESIGN: Comparative study. OBJECTIVES: To compare the outcomes of unilateral TLIF, bilateral TLIF using Wiltse approach and bilateral TLIF using conventional midline approach. SUMMARY OF LITERATURE REVIEW: There are many studies about outcomes of Unilateral TLIF, but few have compared the 3 different fusion procedures. MATERIALS AND METHODS: 60 patients were divided into 3 groups. Each group has enrolled 20 patients (Study group: unilateral TLIF, Control group 1: bilateral TLIF using Wiltse approach, Control group 2: bilateral TLIF using conventional midline approach). For clinical outcomes, we compared operative time, blood loss, time for ambulation and discharge, VAS for back pain and leg pain and ODI among three groups. For radiologic evaluation, disc height and segmental lordosis were examined. RESULTS: The mean operative time was 147 minutes in study group(SG), 172 minutes in control group 1(CG1), 167 minutes in control group 2(CG2). The mean total blood loss was 466ml in SG, 569ml in CG1, 1140ml in CG2 respectively. VAS for back pain at the third postoperative day significantly decreased in SG and CG1 compared with CG2. There was no significant difference in ODI, disc height and segmental lordosis among the groups. CONCLUSION: Using Wiltse approach, there were several advantages in decreasing blood loss, immediate postoperative back pain, hospital stay and early ambulation. Clinical and radiological results of unilateral TLIF were comparable with bilateral TLIF.

Erratum: Surgical Experience of Neglected Lower Cervical Spine Fracture in Patient with Ankylosing Spondylitis

There has been a mistake, claimed and confirmed by both first and corresponding author of Vol. 48, 2010, p.66-69 issue, that corresponding author should have been Dae-Jean Jo, M.D. instead of Eun-Min Seo, M.D. who was also the first author of this issue. It was found that such error was made during the process of final submission of the manuscript and editorial board of JKNS had investigated and had found out such claimed error was relevant and thus permitted for the correction and announcement of erratum in this issue.