Surgical sequence in anterior column realignment with posterior osteotomy is important for degree of adult spinal deformity correction: advantages and indications for posterior to anterior sequence.

BACKGROUND: We hypothesized that posterior osteotomy prior to ACR (Anterior column realignment) through P-A-P surgical sequence would permit a greater correction for deformity corrective surgery than the traditional A-P sequence without posterior osteotomy. This study aimed to determine the impact of the P-A-P sequence on the restoration of lumbar lordosis (LL) compared to the A-P sequence in deformity corrective surgery for adult spinal deformity (ASD) patients and to identify the characteristics of patients who require this sequence.  METHODS: Between 2017 and 2019, 260 ASD patients who had undergone combined corrective surgery were reviewed retrospectively. This study included 178 patients who underwent posterior osteotomy before the ACR (P-A group) and 82 patients who underwent the A-P sequence (A-P group). Sagittal spinopelvic parameters were determined from pre- and postoperative whole-spine radiographs and compared between the groups. To find better indications for the P-A-P sequence, we conducted additional analysis on postoperative outcomes of patients in the A-P group.  RESULTS: The P-A group showed a significantly higher change in LL (53.7° vs. 44.3°, p < 0.001), C7 sagittal vertical axis (C7 SVA: 197.4 mm vs. 146.1 mm, p = 0.021), segmental lordosis (SL) L2/3 (16.2° vs. 14.4°, p = 0.043), SL L3/4 (16.2° vs. 13.8°, p = 0.004), and SL L4/5 (15.1° vs. 11.3°, p = 0.001) compared to the A-P group. At the final follow-up, pelvic incidence (PI) minus LL mismatch (PI - LL mismatch) was significantly higher in the A-P group (13.4° vs. 2.9°, p < 0.001). Stepwise logistic regression analysis showed that age ≥ 75 years (odds ratio [OR] = 2.151; 95% confidence interval [CI], 1.414-3.272; p < 0.001), severe osteoporosis (OR = 2.824; 95% CI, 1.481-5.381; p = 0.002), rigid lumbar curve with dynamic changes in LL < 10° (OR = 5.150; 95% CI, 2.296-11.548; p < 0.001), and severe facet joint osteoarthritis (OR = 4.513; 95% CI, 1.958-10.402; p < 0.001) were independent risk factors for PI - LL mismatch ≥ 10° after A-P surgery. CONCLUSION: P-A-P sequence for deformity corrective surgery in ASD offers greater LL correction than the A-P sequence. Indications for the procedure include patients aged ≥ 75 years, severe osteoporosis, rigid lumbar curve with dynamic change in LL < 10°, or more than four facet joints of Pathria grade 3 in the lumbar region.

Surgical correction for adult spinal deformity increases acetabular lateral coverage of femoral heads.

BACKGROUND: Studies explaining the relationship between hip and spine reported that spinal corrective surgery affected acetabular orientation and changes in pelvic tilt were capable of influencing radiographic measures of acetabular coverage. This study aimed to assess the change in coronal parameters for acetabular coverage as a result of adult spinal deformity (ASD) correction and to analyze the relationship between the postoperative changes in sagittal spinopelvic parameters and coronal acetabular coverage parameters. METHODS: Fifty-two consecutive patients who had undergone multilevel spinal surgical correction were enrolled and evaluated. Coronal acetabular coverage parameters included Tönnis angle (TA), lateral center edge angle (LCEA), and the angle of Sharp (SA). All radiographic parameters were evaluated at the preoperative and the postoperative 1 year. Paired t test was used to determine whether there were significant changes between the time points. Bivariate correlation and linear regression analysis were used to assess the relationship between the postoperative changes of spinal alignment and acetabular orientation. RESULTS: The surgical correction resulted in significant decrease of TA, increase of LCEA and SA, respectively (p < 0.001). The changes in pelvic tilt (PT) demonstrated weak correlation on TA (ß = 0.117, p < 0.001 for right; ß = 0.111, p < 0.001 for left). CONCLUSIONS: Although the surgical correction of ASD significantly changed PT resulting in increased acetabular lateral coverage parameters, the correlation between the changes of PT following sagittal correction of ASD and acetabular coverage parameters was low. TRIAL REGISTRATION: This study was retrospectively registered with approval by the institutional review board (IRB) of our institution (approval number: KHNMC-2020-10-010).

Use of iliac screw associated with more correction of lumbar lordosis than S2-alar-iliac screw for adult spinal deformity.

BACKGROUND: To date, there is a paucity of reports clarifying the change of spinopelvic parameters in patients with adult spinal deformity (ASD) who underwent long segment spinal fusion using iliac screw (IS) and S2-alar-iliac screw (S2AI) fixation. METHODS: A retrospective review of consecutive patients who underwent deformity correction surgery for ASD between 2013 and 2017 was performed. Patients were divided into two groups based on whether IS or S2AI fixation was performed. All radiographic parameters were measured preoperatively, immediately postoperatively, and the last follow-up. Demographics, intraoperative and clinical data were analyzed between the two groups. Additionally, the cohort was subdivided according to the postoperative change in pelvic incidence (PI): subgroup (C) was defined as change in PI ≥5° and subgroup (NC) with change < 5°. In subgroup analyses, the 2 different types of postoperative change of PI were directly compared. RESULTS: A total of 142 patients met inclusion criteria: 111 who received IS and 31 received S2AI fixation. The IS group (65.6 ± 26°, 39.8 ± 13.8°) showed a significantly higher change in lumbar lordosis (LL) and upper lumbar lordosis (ULL) than the S2AI group (54.4 ± 17.9°, 30.3 ± 9.9°) (p < 0.05). In subgroup (C), PI significantly increased from 53° preoperatively to 59° postoperatively at least 50% of IS cohort, with a mean change of 5.8° (p < 0.05). The clinical outcomes at the last follow-up were significantly better in IS group than in S2AI group in terms of VAS scores for back and leg. The occurrence of sacroiliac joint pain and pelvic screw fracture were significantly greater in S2AI group than in IS group (25.8% vs 9%, p < 0.05) and (16.1% vs 3.6%, p < 0.05). CONCLUSIONS: Compared with the S2AI technique, the IS technique usable larger cantilever force demonstrated more correction of lumbar lordosis, and possible increase in pelvic incidence. Further study is warranted to clarify the clinical impaction of these results.

How does long thoracolumbar realignment surgery of adult spinal kyphotic deformity affect lower extremity compensation? Using full body radiograph.

PURPOSE: By using full body radiograph, the aim of the current study was to elucidate the expected degree of lower extremity compensatory change after long thoracolumbar realignment surgery with adult spinal deformity patient who had normal or only mild osteoarthritis on lower extremities. METHODS: Two novel parameters were used for assessment of regional compensation of the lower extremity. The Pearson correlation test was used to assess the correlation of postoperative changes of lower extremity compensation with the other spinopelvic parameters. RESULTS: Overall, 113 spinal deformity patients (mean age was 54.5 years) were recruited and the average number of fused vertebrae was 13.3 ± 3.5. Except pelvic tilt (PT), postoperative sacrum-femur angle (SF) changes showed only moderate correlation with all angular spinopelvic parameters (r = 0.323-0.374; p < .001 to p = .001). Also C7 sagittal vertical axis showed no significant correlation with SF (p = .584-.621). However, postoperative changes of sagittal femur-tibia angle (SFT) reported strong correlation with all parameters evaluated (r = 0.455-0.586; p < .001 to p = .046). CONCLUSION: For adult spinal deformity patients who had normal or only mild osteoarthritis on the lower extremities underwent long thoracolumbar realignment surgery, the surgeon could expect improvement of compensatory change of the knee with correction of spinopelvic parameters. However, the degree of hip compensation improvement was relatively difficult to predict than that of the knee, except PT.

Radiographic and clinical evidence: osteoarthritic knee can change surgical result for lumbar degenerative disease patient undergone surgery for 3-year follow-up: a retrospective comparative clinical study.

BACKGROUND: There is a paucity of reports clarifying the implication of knee osteoarthritis (OA) on spinal sagittal alignment of patients undergone surgery for lumbar spine. This study aimed to analyze how osteoarthritic knee affects radiographic and clinical results of degenerative lumbar disease patients undergone lumbar fusion. METHODS: We retrospectively reviewed the medical records and radiographs of 74 consecutive degenerative lumbar disease patients who underwent posterior instrumentation and fusion surgery between May 2016 and June 2017 and were followed up for minimum 3 years postoperatively. The patients were divided into 2 groups according to the severity of knee OA by Kellgren-Lawrence grading (KLG) scale (group I, KLG 1 or 2 [n = 39]; group II, KLG 3 or 4 [n = 35]). Patient demographic data, comorbidities, spinal sagittal parameters and clinical scores were extracted and compared at preoperative, postoperative 1 month and the ultimate follow-up between the groups. In radiographic assessment, sagittal alignment parameters and sagittal balance were used. In clinical assessment, the scores of Oswestry disability index (ODI) and Scoliosis Research Society questionnaire (SRS-22) were used. For the frequency analysis of categorical variables across the groups, chi-square test was used and student t tests was used to compare the differences of continuous variables. RESULTS: In radiographic assessment, TLK (thoracolumbar kyphosis), LL (lumbar lordosis), PT (pelvic tilt), C7 SVA (sagittal vertical axis) in both groups improved significantly after surgery (p <  0.05). However, LL, PT, C7SVA improved at postoperative 1 month in the group II were not maintained at the ultimate postoperative follow-up. In clinical assessment, preoperative Oswestry disability index (ODI, %) and all SRS-22 subscores of the group I and II were not different (p > 0.05). There were significant differences between the groups at the ultimate follow-up in ODI (- 25.6 vs - 12.1, p <  0.001), SRS total score (%) (28 vs 20, p = 0.037), function subscore (1.4 vs 0.7, p = 0.016), and satisfaction subscore (1.6 vs 0.6, p < 0.001). CONCLUSION: Osteoarthritic knee with KLG 3 or 4 have a negative influence on maintaining postoperative spinal sagittal alignment, balance, and the clinical outcomes achieved immediately by posterior instrumentation and fusion for lumbar degenerative disease. TRIAL REGISTRATION: This study was retrospectively registered with approval by the institutional review board (IRB) of our institution (approval number: 2018-11-007).

Oblique retroperitoneal approach for lumbar interbody fusion from L1 to S1 in adult spinal deformity.

In recent years, with advancements in surgical techniques and instrumentation, the lateral lumbar interbody fusion is being used increasingly as an alternative procedure to anterior approach. In this study, we illustrated a oblique retroperitoneal approach for lumbar interbody fusion with one incision site and tilting of the operation table in adult spinal deformity and evaluate the radiographical findings and clinical outcomes of patients treated using this technique. This study included 32 patients scheduled to undergo anterior and posterior long-level fusions for lumbar degenerative kyphosis or degenerative lumbar scoliosis. Data collected included blood loss, operative time, incision size, and perioperative complications. Pre- and postoperative radiographic parameters and clinical outcome measures were assessed. Mean follow-up time was 26.1 months. The mean blood losses were 107.4 and 102.4 ml, and the mean operative times were 116, 97, and 82 min for the patients within five levels (4 cases), four levels (18 cases), and three levels (10 cases). The mean incision sizes were 14.63, 13.82, and 12.5 cm in the patients with five, four, and three levels. The mean pelvic incidence was 50.3°. The mean preoperative sagittal vertical axis (SVA) was + 13.66 cm, and the last follow-up SVA was + 2.94 cm. The preoperative lumbar lordosis (LL) was 5.79°, and the last follow-up LL was 46.54°. The mean correction angle was 41°. The mean Cobb angle decreased from a preoperative value of 21.55° to 9.6°at the last follow-up. An oblique retroperitoneal approach is very safe, allowing reproducible access from L1 to S1 for lumbar interbody fusion in adult spinal deformity.

The effectiveness of low-dose and high-dose tranexamic acid in posterior lumbar interbody fusion: a double-blinded, placebo-controlled randomized study.

PURPOSE: Tranexamic acid is a proven drug used for reduction of intraoperative blood loss in spinal surgery. However, optimal dosing considering risk/benefits is not well established owing to the heterogeneity in patient selection and surgical procedures of previous studies. This study aimed to evaluate the effectiveness and safety of various tranexamic acid regimens in reducing perioperative blood loss in single-level posterior lumbar interbody fusion (PLIF). METHODS: Patients were randomly grouped into three different interventions: low-dose tranexamic acid (LD), high-dose tranexamic acid (HD), and placebo-controlled (PC) groups. The HD and LD groups received 10 and 5 mg/kg of bolus loading dose and 2 and 1 mg/kg of continuous infusion until 5 h after surgery, respectively. Data on patient demographics and preoperative and 24-h postoperative laboratory values were collected. Outcome parameters include intraoperative blood loss, 24-h postoperative blood loss, and blood loss during removal of the last drain. RESULTS: Seventy-two patients (mean age 63.3 ± 7.6 years) showed similar baseline characteristics. Intraoperatively, blood loss was reduced by the administration of tranexamic acid (P = 0.04), contributed predominantly by a difference between the LD and HD groups (123 mL; P < 0.01). The 24-h postoperative blood loss was reduced (P < 0.01), contributed predominantly by a difference between the PC and LD groups (144 mL; P = 0.02). During the removal of the last drain, statistical difference was found between the PC and HD groups (125 mL; P = 0.00). No complications or side effects from tranexamic acid use were noted. CONCLUSION: Tranexamic acid administration for single-level PLIF was effective and safe in reducing perioperative blood loss in a dose-dependent manner. An HD regimen comprising 10 mg/kg of bolus loading dose and 2 mg/kg/h of continuous infusion is recommended. LEVEL OF EVIDENCE: Level 1 study according to Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence.

Overcorrection of lumbar lordosis for adult spinal deformity with sagittal imbalance: comparison of radiographic outcomes between overcorrection and undercorrection.

PURPOSE: To determine the correlation of the difference between postoperative lumbar lordosis (LL) and ideal LL with the sagittal vertical axis (SVA) at the final follow-up in patients with adult spinal deformity (ASD). METHODS: Fifty-one patients with degenerative lumbar kyphosis (DLK) (mean age 66.5 years) who underwent surgical correction with a minimum 2-year follow-up were evaluated. Based on the difference between postoperative LL and ideal LL using the Korean version of Legaye's formula, we divided the 51 patients into two groups: overcorrection (degree of postoperative LL > ideal LL) and undercorrection (degree of postoperative LL < ideal LL). RESULTS: Our clinical series of patients comprised 24 in the overcorrection and 27 in the undercorrection group. No significant differences were found in preoperative pelvic incidence (PI 52.6° vs. 57.3°), sacral slope (SS 23.3° vs. 18.3°), LL (-6.9° vs. -2.3°), thoracic kyphosis (TK 4.7° vs. 4.9°) and SVA (140 vs. 139 mm) except pelvic tilt (PT 29.4° vs. 39.0°), between the two groups. All the patients in the overcorrection group and 16 in the undercorrection group achieved postoperative optimal sagittal balance based on SVA ≤ 50 mm. In addition, significant differences in PT (10.5° vs. 26.7°), SS (42.1° vs. 30.6°), LL (-64.3° vs. -37.1°), TK (22.6° vs. 15.8°), and SVA (-1 vs. 41 mm) between the two groups were observed postoperatively. Furthermore, four patients (16.7 %) in the overcorrection group and eight (50 %) in the undercorrection group had sagittal decompensation at the final follow-up. Our results showed that the difference between postoperative LL and ideal LL had a significant correlation with postoperative and final follow-up SVA in our clinical series. CONCLUSION: Overcorrection of LL is an effective treatment modality to maintain optimal sagittal alignment in patients with DLK; this suggests that it should be considered in preoperative planning for patients with ASD with sagittal imbalance.

Anterior Column Realignment Through Open Pre-posterior Release-Anterior-Posterior Fusion Versus Hybrid Minimally Invasive-Anterior-Posterior Fusion for Dynamic Sagittal Imbalance of the Spine.

STUDY DESIGN: Retrospective comparative study. OBJECTIVES: To investigate the clinical and radiological outcomes after anterior column realignment (ACR) through pre-posterior release-anterior-posterior surgery (PAP) and minimally invasive surgery -lateral lumbar interbody fusion (MIS-LLIF) using hybrid anterior-posterior surgery (AP). METHODS: A total of 91 patients who underwent ACR with long fusions from T10 vertebra to the sacropelvis with a follow-up period of at least 2 years after corrective surgery for adult spinal deformity were included and divided into two groups by surgical method: AP and PAP. AP was performed in 26 and PAP in 65 patients. Clinical outcomes and radiological parameters were investigated and compared. A further comparison was conducted after propensity score matching between the groups. RESULTS: The more increase of LL and decrease of PI-LL mismatch were observed in the PAP group than in the AP group postoperatively. After propensity score matching, total operation time and intraoperative bleeding were greater, and intensive care unit care and rod fracture were more frequent in the PAP group than in the AP group with statistical significance. Reoperation rate was higher in PAP (29.2%) than in AP (16.7%) without statistical significance. CONCLUSIONS: PAP provides a more powerful correction for severe sagittal malalignment than AP procedures. AP results in less intraoperative bleeding, operation time, and postoperative complications. Therefore, this study does not suggest that one treatment is superior to the other. LEVEL OF EVIDENCE: III.

Reoperation depending on time period following pedicle subtraction osteotomy for thoracolumbar kyphosis in patients with ankylosing spondylitis.

OBJECTIVE: The aim of this study was to investigate time-dependent rates and indications of unplanned reoperation and to evaluate the most common indication depending on the time interval after pedicle subtraction osteotomy (PSO) for correction of thoracolumbar kyphosis in patients with ankylosing spondylitis (AS). METHODS: A total of 321 consecutive patients with AS (284 men; mean age 43.8 years) with thoracolumbar kyphosis who underwent PSO were included. Patients who underwent reoperation after the index surgery were divided according to the duration of the follow-up period. RESULTS: A total of 51 patients (15.9%) underwent unplanned reoperations. The reoperation groups had greater preoperative and postoperative C7 sagittal vertical axis (SVA), and less lordotic postoperative osteotomy angle (-4.3° ± 18.6° vs -15.0° ± 13.7°, p < 0.001). The perioperative change in SVA was not significantly different between groups (-10.0 ± 7.1 cm vs -10.0 ± 5.1 cm, p = 0.970), while that in the osteotomy angle was significantly different (-22.4° ± 21.3° vs -30.0° ± 11.5°, p = 0.014). Most reoperations (45.1%; 23/51) were performed within 2 weeks of the initial operation. Within 2 weeks, the most common cause of reoperation was neurological deficit in 10 patients, with a cumulative reoperation rate of 3.2%. After 3 years, the most common complications were mechanical complications in 8 patients, accounting for 15.7% (8/51) of patients. Overall, the most common indications for reoperation were mechanical complications (17 patients; 5.3%), followed by neurological deficits (12 patients; 3.7%). CONCLUSIONS: PSO may be the most effective surgical procedure for the correction of thoracolumbar kyphosis in patients with AS. However, 51 patients (15.9%) required an unplanned reoperation.

Association of interferon gamma polymorphism with ossification of the posterior longitudinal ligament in the korean population.

In this study, we investigated whether genetic polymorphisms of the interferon gamma (IFNG) gene were associated with the susceptibility of ossification of the posterior longitudinal ligament (OPLL) in the Korean population. To observe the association between the IFNG gene and the susceptibility of OPLL, we genotyped 135 OPLL patients and 222 control subjects for a single nucleotide polymorphism (SNP, rs2430561) and a microsatellite (CA(n) repeats, rs3138557) located in the first intron of the IFNG gene, using the direct sequencing and gene scan method. The numbers of microsatellites (CA(13) and CA(15)) were significantly changed in the OPLL patients. A combined analysis of the genotype of rs2430561 and the number of microsatellites revealed that the OPLL was associated with frequencies of CA(13)-AA, CA(15)-AA and CA(15)-AT. Our results suggest that the IFNG gene may be one of the factors determining the OPLL in the Korean population. However, larger collaborative and biological studies are needed to confirm these results.

Does it need to perform anterior column support after Smith-Petersen osteotomy for ankylosing spondylitis?

PURPOSE: The aim of this study was to determine whether anterior column support is required in Smith-Petersen osteotomy procedure with correction angles of more than 10°, while examining the subsequent healing patterns in relation to the disrupted area. METHODS: An analysis was done on 26 segments of 19 patients who showed a correction angle of more than 10° in the anterior opening after SPO. There were 17 male and two female patients with a mean age of 40 years (24-56 years). The mean follow-up period was 6.5 years (2-9.1 years). The patients were classified according to the site of the anterior opening, as the disc level, the lower end-plate of the upper body (upper body), or the upper end-plate of the lower body (lower body). The healing patterns of anterior opening and the radiological correction angles were evaluated relative to the opening site. RESULTS: In all cases, bony fusion was confirmed at a mean period of 5.6 months (3-6.7 months) after surgery and the anterior opening gap was healed in 18 segments (69.2%). For patients that developed an opening in the upper body, all of the gaps were healed. The gaps in the lower body opening group were healed in 85.7% of the cases, and for the opening at the disc level, the gaps were healed only in 12.5% of the cases. The least amount of correction was obtained when anterior opening occurred in disc level. CONCLUSIONS: In our study of subjects presenting with anterior opening angles from 10° to 32°, we obtained successful fusion without the need for additional anterior interbody fusion. Improved gap healing and increased correction angles were obtained when the opening was present in the upper or lower body endplates compared to those at the disc space level.

Cervical pedicle screw placement using the "key slot technique": the feasibility and learning curve.

STUDY DESIGN: A retrospective study. OBJECTIVES: To present the accuracy and safety of a novel "key slot (KS)" technique for cervical pedicle screw (CPS) placement with the learning curve. SUMMARY OF BACKGROUND DATA: Safety and learning curve are the issues preventing wide acceptance of CPS. On the basis of the local anatomy of the pedicle, the authors modified the conventional technique to increase the accuracy and comfortableness of CPS placement with minimal bone loss. METHODS: A total of 277 subaxial CPS in 50 patients had been inserted using author's technique were reviewed. The KS-shaped entry was created on the medial half of the lateral mass with a 3 mm cutting burr. The shape of entry was a right-angled triangle on the axial plane. The apex of triangle was the virtual pedicle inlet and the oblique side was same as pedicle axis. After making entry, the pedicle was probed with a curved awl along the medial wall. On the postoperative vascular-enhanced computed tomography scan, we analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1:< 25%, 2: 20% to 50%, 3: > 50% of screw diameter) on the chronological group of consecutive 10 cases. Grade 2 and 3 were considered as incorrect position. RESULTS: The correct position was found in 250 screws (90.3%); grade 0 - 215 screws, 1 - 35 screws and the incorrect position in 27 screws (9.7%); grade 2 - 21 screws, grade 3 - 6 screws. The incidence of incorrect screw position was 18% in the initial 20 cases and 2.7% after that. There was no neurovascular complication related with CPS. CONCLUSIONS: We performed CPS placement using the KS technique and with 90% correct position without clinical complications. After the learning curve, the incidence was 2.7%. This technique could be considered relatively concrete and safe modification of conventional technique with minimal bone loss.

The influence of thoracic inlet alignment on the craniocervical sagittal balance in asymptomatic adults.

STUDY DESIGN: A prospective radiographic study. OBJECTIVES: To analyze the relationship between craniocervical sagittal balance and thoracic inlet (TI) alignment and to present the parameters that would help predict physiological lordosis of the cervical spine. SUMMARY OF BACKGROUND DATA: The physiological cervical lordosis (CL) and related factors has not been clearly defined yet. No studies have reported correlations between TI alignment and sagittal balance of the cervical spine. METHODS: Cervical spine lateral radiograph of 77 asymptomatic adult volunteers (aged between 21 and 50 y) were taken to analyze the following parameters. (1) Thoracic inlet parameters: thoracic inlet angle (TIA), T1 slope, neck tilting (NT); (2) cervical spine parameters: C0-2 angle, C2-7 angle, % ratio of (C0-2/C0-7 angle), (C2-7/C0-7 angle), and cervical tilting; (3) cranial parameters: C0 angle, cranial offset, and cranial tilting. Statistical analysis was performed using the Pearson correlation coefficients and multiple regression analysis. RESULTS: The mean TIA, T1 slope, NT were 69.5, 25.7, and 43.7, respectively. The mean C0-2 angle, C2-7 angle, C0 angle, cranial offset, cervical tilting, and cranial tilting were -22.4 degrees, -9.9 degrees, -9.3 degrees, 20.9 mm, 18 degrees, and 7.7 degrees, respectively. The ratio of C0-2:C2-7 angle was maintained as 77:23% and cervical tilting:cranial tilting was 70.2:29.8%. A significant correlation was found between TIA and T1 slope (r=0.694), T1 slope and C2-7 angle (r=-0.624), C2-7 angle and C0-2 angle (r=-0.547), C0-2 angle and cranial offset (r=-0.406). CONCLUSIONS: The thoracic inlet alignment had significant correlations with craniocervical sagittal balance. To preserve physiological NT around 44 degrees, large TIA increased T1 slope and CL and vice versa. TIA and T1 slope could be used as parameters to predict physiological alignment of the cervical spine. The results of this study may serve as baseline data for the evaluation of sagittal balance or planning of a fusion angle in the cervical spine.

Pedicle Subtraction Osteotomy in Adult Spinal Deformity: Comparing Fixed Versus Flexible Sagittal Imbalance.

STUDY DESIGN/SETTING: Level III-retrospective radiologic and clinical comparative study. OBJECTIVE: This study compares the results of pedicle subtraction osteotomy (PSO) for fixed versus flexible sagittal imbalance in adult spinal deformity. SUMMARY OF BACKGROUND DATA: The result of PSO may be different according to the flexibility of the deformity. METHODS: Sixty-one patients who underwent PSO were enrolled with a minimum 2-year follow-up. Twenty-one patients had fixed imbalance resulting from ankylosing spondylitis and iatrogenic flatback deformity, and 40 patients had flexible imbalance resulting from degenerative spinal deformity and posttraumatic kyphosis. RESULTS: The mean age was 54.9±9.2 years in the fixed group and 65.9±10.5 years in the flexible group (P<0.01). PSO achieved about 35 degrees of correction of kyphotic angle in both groups, but the loss of correction (LOC) was higher in the flexible group. The correction of Lumbar Lordosis was similar in both groups, at 31.7±15.4 degrees in the fixed group and 32.3±20.8 degrees in the flexible group, although the LOC was also higher in the flexible group than in the fixed group, at 9.8±12.4 and 2.7±3.5 degrees, respectively (P<0.01). The sagittal vertical axis was much more restored in the fixed group than in the flexible group (P=0.002). Postoperative complications were identified in 4 patients in the fixed group, consisting of neurological deficit and screw loosening, and in 15 patients in the flexible group, consisting of proximal junctional kyphosis, screw pullout, rod fracture, and pseudarthrosis. CONCLUSIONS: PSO for flexible sagittal imbalance resulted in a higher LOC of the osteotomy angle, Lumbar Lordosis, and sagittal vertical axis relative to the fixed deformity. Furthermore, more complications such as implant failure developed in the flexible group.

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

STUDY DESIGN: This is a retrospective comparative cohort study. PURPOSE: To investigate the prevalence of anterior resorption of the cervical spine in ankylosing spondylitis (AS) and its relationship with sagittal alignment. OVERVIEW OF LITERATURE: This study believes that no published reports exist regarding the relationship between anterior resorption and spinopelvic alignment. 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.

Improvements in lower-extremity patient-reported outcomes after lumbar interbody fusion.

OBJECTIVE: Recently, new patient-reported outcome measures (PROMs) of the spine were designed to overcome the limitations of previous spinal PROMs and to consider the whole spine as a single kinetic functional unit. Owing to the significance of spine-hip-knee and global body balance, the spine and lower extremities cannot be considered separately. However, no reports have evaluated lower-extremity functional outcome using PROMs after lumbar spine surgery. The authors aimed to elucidate changes in hip and knee PROMs after lumbar interbody fusion and to evaluate the sagittal spinopelvic radiographic parameters that were most strongly correlated with lower-extremity PROMs. METHODS: In 2018, the authors consecutively evaluated patients who underwent lumbar interbody fusion surgery with at most three levels. Preoperative and 1-year postoperative clinical and radiographic data were assessed. Spinal functional outcomes were measured with the Oswestry Disability Index (ODI), visual analog scale (VAS) for pain, and Scoliosis Research Society-22r (SRS-22r) questionnaire. Lower-extremity functional outcomes were evaluated with the Harris Hip Score (HHS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Linear regression was used to evaluate the relationship between spinal and lower-extremity PROMs and spinopelvic radiographic parameters. RESULTS: The authors enrolled 67 patients, with a mean age of 66.4 years. The average number of surgical levels was 1.7. All assessed PROMs improved significantly after surgery (p < 0.001 for ODI, p < 0.001 for VAS, p = 0.017 for SRS-22r, p = 0.042 for HHS, and p = 0.033 for WOMAC). Spinopelvic parameters, including lumbar lordosis (LL), pelvic tilt (PT), C7 sagittal vertical axis, and sagittal radiographic parameters of hip and knee, significantly improved after surgery. On linear regression analysis, HHS and WOMAC correlated with LL and PT, respectively (ß = 0.554 and p = 0.043 for correlation of HHS with LL; ß = 1.573 and p = 0.021 for correlation of WOMAC with PT). CONCLUSIONS: The current study demonstrated that lumbar fusion surgery may induce postoperative improvements in lower-extremity functional and radiological outcomes. However, among radiographic parameters, changes in LL and PT were the most strongly associated with lower-extremity PROMs.

Association between interleukin 15 receptor, alpha (IL15RA) polymorphism and Korean patients with ossification of the posterior longitudinal ligament.

OBJECTIVES: Recently, a number of evidences have been reported concerning the genetic factor involved in the development of ossification of the posterior longitudinal ligament (OPLL). The purpose of this study was to investigate single nucleotide polymorphisms (SNPs) of the interleukin 15 receptor, alpha (IL15RA) gene as a risk factor in Korean patients with OPLL. DESIGN: To investigate the genetic association, two coding SNPs (rs2296139, Thr73Thr; rs2228059, Asn182Thr) in IL15RA were genotyped in 166 OPLL patients and 230 control subjects. SNPStats, SNPAnalyzer, and Helixtree programs were used for association analysis. RESULTS: In the present study, we found the association between a missense SNP (rs2228059) and the risk of OPLL in codominant (p = 0.0028, OR = 1.58, 95% CI = 1.17-2.14), dominant (p = 0.0071, OR = 1.82, 95% CI = 1.17-2.82), and recessive models (p = 0.036, OR = 1.79, 95% CI = 1.04-3.09). The frequency of rs2228059 allele was significantly associated with the susceptibility of OPLL (p = 0.0043, OR = 1.52, 95% CI = 1.14-2.02). After Bonferroni correction, the missense SNP (rs2228059, Asn182Thr) still had significant correlations (p = 0.0056 in codominant model; p = 0.0142 in dominant model; p = 0.0086 in allele analysis). Haplotype variation in IL15RA was associated with OPLL (global haplotype test, p = 0.025). CONCLUSIONS: These results suggest that IL15RA polymorphism may be associated with the susceptibility of OPLL in Korean population.

Trajectory of transsacral iliac screw for lumbopelvic fixation: a 3-dimensional computed tomography study.

STUDY DESIGN: A 3-dimensional multi detector computed tomography study. OBJECTIVE: To analyze the optimal trajectory of the transsacral iliac screw (TSIS) to overcome the disadvantages of the conventional iliac screw. SUMMARY OF BACKGROUND DATA: Iliac screw fixation increased lumbosacral fusion rate. However, its disadvantages have been reported including extensive muscle dissection, loss of the posterior superior iliac spine (PSIS), need of additional connecting device, screw breakage, and pain from prominence. METHODS: Three-dimensionally reconstructed multi detector computed tomography images on the pelvis of 60 patients (M:F=30:30, age 20 to 50) were analyzed. The virtual trajectory started from the point where the center of S2 ala met the lateral sacral crest and targeted the superior rim of acetabulum, across the sacroiliac joint. On the basis of the virtual trajectory, the oblique sagittal, oblique axial, oblique coronal plane, and 3-dimensional surface rendering images were obtained. The optimal insertion angle in the 3 planes, the maximal length and diameter of screw were measured. Relationships between the trajectory and structures under risk were analyzed. RESULTS: The safe insertion angle was 38±3.5 degrees in the axial plane and 86±6.5 degrees in the sagittal plane based on the posterior surface of the sacrum. The mean length and maximal diameter of optimal trajectory was 91 and 18 mm, respectively. When the screw was inserted within 25 degrees in the axial plane, and exceeding 95 degrees in the sagittal plane, the external iliac vessels and the superior gluteal arteries were at risk. CONCLUSIONS: The TSIS could be safely inserted without increasing the general risk of conventional iliac screw. On the basis of the result of this study, we consider the TSIS technique a useful option for lumbopelvic fixation to overcome disadvantages of iliac screw.

Extent and characteristic of relationships in canal dimension and canal body ratio between cervical and lumbar spine.

A known prevalence of concurrent cervical and lumbar spinal stenosis was shown to be 5-25%, but there is a lack of evidence regarding direct relationships in canal dimension and canal-body ratio between cervical and lumbar spine. Total 247 patients (mean age: 61 years, male: 135) with cervical and lumbar computed tomography scans were retrospectively reviewed. Midsagittal vertebral body and canal diameters in reconstructed images were measured at all cervical and lumbar vertebrae, and canal-body ratios were calculated. The canal diameter and ratio were also compared according to the gender and age, and correlation analysis was performed for each value. There were significant correlations between cervical (C3-C7) and lumbar (L1-L5) canal dimension (p < 0.001). C5 canal diameter was most significantly correlated with L4 canal diameter (r = 0.435, p < 0.001). Cervical canal-body ratios (C3-C7) were also correlated with those of lumbar spine (L1-L5) (p < 0.001). The canal-body ratio of C3 was most highly correlated with L3 (r = 0.477, p < 0.001). Meanwhile, mean canal-body ratios of C3 and L3 were significantly smaller in male patients than female (p = 0.038 and p < 0.001) and patient's age was inversely correlated with C5 canal diameter (r = - 0.223, p < 0.001) and C3 canal-body ratio (r = - 0.224, p < 0.001). Spinal canal dimension and canal-body ratio have moderate degrees of correlations between cervical and lumbar spine and the elderly male patients show the tendency of small canal diameter and canal-body ratio. This relationship of cervical and lumbar spine can be an important evidence to explain to the patients.