Transpedicular closed wedge osteotomy in ankylosing spondylitis: results of surgical treatment and prospective outcome analysis

A new mathematical model for evaluating surface changes in the mid-abdominal sagittal plane after two-level pedicle reduction osteotomy in patients with ankylosing spondylitis

BACKGROUND

The purpose of this study was to create a mathematical model to precalculate the acreage change in the abdominal median sagittal plane (ac-AMSP) of patients with ankylosing spondylitis (AS) for whom two-level pedicle subtraction osteotomy (PSO) was planned.

METHODS

A single-centre retrospective review of prospectively collected data was conducted among 11 adults with AS. Acreage of the abdominal median sagittal plane (a-AMSP) was performed. The distances and angles between the osteotomy apexes, anterosuperior edge of T12, xiphoid process, superior edge of the pubis, and anterosuperior corner of the sacrum were measured on preoperative thoracolumbar computed tomography. A mathematical model was created using basic trigonometric functions in accordance with the abdominal parameters. Planned osteotomized vertebra angles (POVAs) were substituted into the mathematical model, and the predictive ac-AMSP (P-AC) was obtained. A paired sample t test was performed to determine the differences between the P-AC and actual ac-AMSP (A-AC) and between the predictive acreage change rate (P-CR) and actual acreage change rate (A-CR).

RESULTS

The mean age and GK were 44.4 ± 8.99 years and 102.9° ± 19.17°, respectively. No significant difference exists between A-CR and P-CR via mathematical modeling (p > 0.05). No statistically significant difference existed between POVA and actual osteotomized vertebra angles (AOVA) (p > 0.05). A statistically significant difference was observed between preoperative and postoperative measurements of LL, SVA, and GK variables (p < 0.001).

CONCLUSIONS

The novel mathematical model was reliable in predicting the ac-AMSP in AS patients undergoing two-level PSO.

Staged osteotomy in lateral position for the treatment of severe kyphotic deformity secondary to ankylosing spondylitis: a retrospective study

BACKGROUND

Patients with severe kyphotic deformity (Cobb > 100°) secondary to ankylosing spondylitis (AS) occasionally cannot undergo corrective surgery in the prone position. Osteotomy in the lateral position might provide a possible solution. In this study, we aim to evaluate the clinical efficacy and safety of staged osteotomy in the lateral position for the treatment of AS-related severe kyphosis with a minimum of 2-year follow-up.

METHODS

In total, 23 patients who underwent staged osteotomy in the lateral position from October 2015 to June 2017 were analyzed. In the first stage of surgery, all but one patient underwent a single-level Ponte osteotomy, which was followed by a pedicle subtraction osteotomy in the second stage. Mean follow-up was 30.8 ± 4.6 months. Global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), osteotomized vertebra intervertebral angle (OVI), chin-brow vertical angle (CBVA), Oswestry Disability Index (ODI) score and Scoliosis Research Society-22 Patient Questionnaire (SRS-22) were all compared pre- and postoperation.

RESULTS

All kyphosis parameters were significantly improved (all P < 0.05). GK was corrected from 115.0 ± 13.4° to 46.5 ± 9.0° postoperatively, with a mean correction of 68.5°. SVA was improved from 21.2 ± 5.1 cm to 5.1 ± 1.8 cm postoperatively. After surgery, CBVA was adjusted from 64.1 ± 23.2° to 5.7 ± 10.6° and OVI was changed from 9.0 ± 2.7° to - 20.1 ± 5.6°. Both the ODI and SRS-22 showed substantial improvements (all P < 0.05). Four patients with mild complications were observed perioperatively.

CONCLUSION

In AS patients with severe kyphosis, satisfactory correction can be safely achieved with staged osteotomy in the lateral position, which can not only correct the sagittal imbalance of the spine with acceptable complications but also facilitate the placement of the intraoperative position.

Clinical outcomes for andersson lesion in patients with ankylosing spondylitis by transforaminal thoracolumbar intervertebral fusion surgery

BACKGROUND

Andersson lesion (AL) is a rare complication of ankylosing spondylitis (AS). Its clinical outcome of surgical treatment needs further exploration.

OBJECTIVE

To evaluate the clinical and radiological outcomes of transforaminal thoracolumbar intervertebral fusion (TTIF) in the treatment of AS patients with thoracolumbar AL.

METHODS

Fourteen patients with thoracolumbar AL who suffered from back pain, spinal instability or kyphotic deformity were retrospectively recruited. The clinical outcomes were evaluated with Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). Radiological outcomes were measured with local kyphotic (LK) angle and general kyphotic (GK) angle.

RESULTS

Before surgical treatment for the AL patients, their VAS score and ODI score was 8.0 ± 0.2 and 64.0 ± 6.9, respectively. After TTIF surgery, VAS score of the patients was improved to 2.4 ± 0.5 (p< 0.01) and ODI score was decreased to 17.0 ± 3.7 (p< 0.01). One patient with neurological deficit showed an improvement in the Frankel grade from C to D and all others were grated E-level before and after surgery. For radiological outcomes, patients' LK angle was reduced from 18.5 ± 7.2 to 11.0 ± 6.4 (p< 0.01) and GK angle was reduced to 38.6 ± 8.8 from 42.8 ± 10.4 (p< 0.01) at the 1-year follow-up.

CONCLUSION

For AS patients with thoracolumbar AL, we propose that TTIF is an effective and safe operative treatment, which can achieve good fusion, satisfactory radiological and clinical outcomes.

Factors influencing complications after 3-columns spinal osteotomies for fixed sagittal imbalance from multiple etiologies: a multicentric cohort study about 286 cases in 273 patients

PURPOSE

Spinal osteotomies performed to treat fixed spinal deformities are technically demanding and associated with a high complications rate. The main purpose of this study was to analyze complications and their risk factors in spinal osteotomies performed for fixed sagittal imbalance from multiple etiologies.

METHODS

The study consisted of a blinded retrospective analysis of prospectively collected data from a large multicenter cohort of patients who underwent 3-columns (3C) spinal osteotomy, between January 2010 and January 2017. Clinical and radiological data were compared pre- and post-operatively. Complications and their risk factors were analyzed.

RESULTS

Two hundred eighty-six 3C osteotomies were performed in 273 patients. At 1 year follow-up, both clinical (VAS pain, ODI and SRS-22 scores) and radiological (SVA, SSA, loss of lordosis and pelvic version) parameters were significantly improved (p < 0.001). A total of 164 patients (59.2%) experienced at least 1 complication (277 complications). Complications-free survival rates were only 30% at 5 years. Most of those were mechanical (35.2%), followed by general (17.6%), surgical site infection (17.2%) and neurological (10.9%). Pre-operative neurological status [RR = 2.3 (1.32-4.00)], operative time (+ 19% of risk each additional hour) and combined surgery [RR = 1.76 (1.08-2.04)] were assessed as risk factors for overall complication (p < 0.05). The use of patient-specific rods appeared to be significantly associated with less overall complications [RR = 0.5 (0.29-0.89)] (p = 0.02).

CONCLUSION

Spinal 3C osteotomies were efficient to improve both clinical and radiological parameters despite high rates of complication. Efforts should be made to reduce operative time which appears to be the strongest predictive risk factor for complication.

Treatment of ankylosing spondylitis complicated with a thoracolumbar Andersson lesion by posterior closed osteotomy, debridement and fusion through the fracture line

Background

An Andersson lesion (AL) is a fatigue fracture occurring across three columns in ankylosing spondylitis (AS), resulting in spinal pseudarthrosis (SP) formation, most commonly in the thoracolumbar segment. However, there is still great controversy and few reports on the best surgical method for the treatment of AS combined with thoracolumbar AL. The purpose of this study was to investigate the efficacy of posterior closed osteotomy, debridement and fusion through the fracture line for the treatment of this disease.

Methods

The clinical data of 13 patients (male 8, female 5, mean age 50.6 years) with AS combined with thoracolumbar AL treated with posterior closed osteotomy, debridement and fusion through the fracture line were retrospectively analysed. The following parameters of the full-length lateral spine radiographs were measured preoperatively and at the last follow-up: cervical 7 tilt (C₇T), global kyphosis (GK), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), local kyphosis (LK), angle of the fusion levels (AFL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and sagittal vertical axis (SVA). The visual analog scale (VAS), Oswestry disability index (ODI) and Scoliosis Research Society-22 (SRS-22) scores were recorded preoperatively and at the last follow-up.

Results

The mean operation time was 345 min, the mean blood loss was 673 mL, and the mean follow-up time was 21.9 months. Compared with the preoperative values, the C₇T, GK, TK, TLK, LK, AFL, PT, SS and SVA values of all patients were significantly improved at the last follow-up (P < 0.05); GK improved from 81.62 ± 16.11 to 50.15 ± 8.55, with an average of 31° of correction (F = 75.945, P<0.001). The VAS, ODI and SRS-22 scores also significantly improved (P < 0.05). At the last follow-up, bone fusion was found in all fracture ends. One patient developed numbness in the lower limbs after surgery and recovered after 3 months of rehabilitation; none of the remaining patients experienced postoperative complications.

Conclusions

Posterior closed osteotomy, debridement and fusion through the fracture line completely removes the necrotic tissue around the SP, relieves symptoms, and corrects kyphosis simultaneously. It reduces the tension behind the fracture line or changes the tension into compressive stress, enabling stable repair of the fracture and avoiding anterior surgery. It is a safe and effective operation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05770-3.

Preoperative prediction of sagittal imbalance in kyphosis secondary to ankylosing spondylitis after one-level three-column osteotomy

Background

This study aimed to determine preoperative predictors for sagittal imbalance in kyphosis secondary to ankylosing spondylitis (AS) after one-level three-column osteotomy.

Methods

A total of 55 patients with AS who underwent one-level three-column osteotomy were enrolled. The patients were divided into two groups according to sagittal vertical axis (SVA) value at the final follow-up (group A: SVA > 5 cm; group B: SVA ≤ 5 cm). The radiographic measures included global kyphosis, lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), sacral slope, T1 pelvic angle (TPA), SVA, osteotomized vertebral angle and PI and LL mismatch (PI − LL). Postoperative clinical outcomes were evaluated using Scoliosis Research Society-22 questionnaire (SRS-22) and Oswestry Disability Index (ODI).

Results

Fifty-five AS patients had an average follow-up of 30.6 ± 10.2 months (range 24–84 months). Group A had larger preoperative and postoperative LL, PT, PI − LL, TPA and SVA values compared with group B (P < 0.05), and no significant differences were found in ODI and SRS-22 scores between the two groups (P > 0.05). Preoperative LL, PT, PI − LL, TPA, and SVA values were positively correlated with the follow-up SVA value (P < 0.05). Among them, TPA > 40.9°, PI − LL > 32.5° and SVA > 13.7 cm were the top three predictors with the best accuracy to predict sagittal imbalance. Immediate postoperative SVA value of ≤ 7.4 cm was a key factor in reducing the risk of sagittal imbalance during follow-up.

Conclusions

Preoperative TPA > 40.9°, PI − LL > 32.5° and SVA > 13.7 cm could predict sagittal imbalance in AS kyphosis after one-level three-column osteotomy, and additional osteotomies were recommended for this condition. Immediate postoperative SVA ≤ 7.4 cm was an optimal indicator for preventing sagittal imbalance.

Level of evidence

IV.

Clinical Results of Utilizing the Satellite Rod Technique in Treating Ankylosing Spondylitis Kyphosis

Objective

According to the literature, there are no clinical reports documenting the use of the satellite rod technique in the treatment of ankylosing spondylitis kyphosis. The purpose of this retrospective study was to compare the clinical outcome of patients with ankylosing spondylitis kyphosis who adopted satellite rods versus those who did not.

Methods

Patients with ankylosing spondylitis kyphosis who underwent one or two‐level pedicle subtraction osteotomy (PSO) were reviewed, and total of 119 patients (112 males and seven females, average age 39.89 ± 6.61 years) were eligible and included in this present study. Anterior–posterior and lateral full‐length spine X‐ray films were performed preoperatively and at the two‐year follow‐up visit. Global kyphosis (GK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), thoracic kyphosis (TK), and osteotomy angle (OA) were measured. The complications of every group of patients were collected. Pre‐ and postoperative health‐related quality of life instruments, including the Bath Ankylosing Spondylitis Functional Index (Basfi) and Scoliosis Research Society outcomes instrument‐22 (SRS‐22), were recorded. The patients were divided into three groups based on features of their osteotomy including PSO levels and whether the satellite rod technique was applied. Patients who underwent one‐level PSO without the satellite rod technique were categorized in the one‐level group. Patients who underwent one‐level PSO with the satellite rod technique were classified in the satellite rod group. Patients who underwent two‐level PSO without the satellite rod technique were included in the two‐level group. The paired sample t test was used to compare pre‐ and postoperative parameters. One‐way ANOVA was performed for multiple group comparisons.

Results

The average follow‐up time is 29.31 ± 3.66 months. The patients' GK were significantly improved from 46.84 ± 20.37 degree to 3.31 ± 15.09 degree. OS achieved through each osteotomy segment of one‐level group (39.78 ± 12.29 degree) and satellite rods group (42.23 ± 9.82 degree), was larger than that of two‐level group (34.73 ± 7.54 and 28.85 ± 7.26 degree). There was no significant difference between the one‐level group and the satellite rod group in achieving the OS. Thirteen patients experienced different complications (10.92%). Three patients experienced rod fracture in the one‐level group. There was no rod fracture or screw failure in the satellite rod group or the two‐level group.

Conclusion

The satellite rod technique is also recommended for patients who undergo PSO osteotomy to correct ankylosing spondylitis kyphosis deformities.

When Can One-level Pedicle Subtraction Osteotomy Obtain Satisfied Outcomes for Severe Thoracolumbar Kyphosis with Global Kyphosis ≥80° in Ankylosing Spondylitis: A Comparison with Two-level Pedicle Subtraction Osteotomy

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to make a thorough comparison of clinical and radiographic outcomes between ankylosing spondylitis (AS) patients with severe kyphosis who underwent one- or two-level pedicle subtraction osteotomy (PSO) and to determine the indications of one-level PSO.

SUMMARY OF BACKGROUND DATA

Traditionally, one-level PSO was considered being able to obtain 35° to 40° correction. However, in our practice, one-level PSO might achieve satisfied clinical and radiographic outcomes in AS patients with severe thoracolumbar kyphosis defined as global kyphosis (GK) ≥80°.

METHODS

Fifty-five AS-related severe thoracolumbar kyphosis patients undergoing one- or two-level PSO from January 2007 to November 2016 were reviewed. The radiographic parameters included thoracic kyphosis (TK), lumbar lordosis (LL), GK, pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), sagittal vertical axis (SVA), and femoral obliquity angle (FOA). Clinical outcomes were evaluated by Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS).

RESULTS

The mean follow-up period was 39.7 ± 20.2 months (range, 24-120 months). Patients who underwent one-level PSO have significantly smaller preoperative GK, SVA, FOA, and larger preoperative LL and SS compared to those who underwent two-level PSO (P < 0.05). The optimal cutoff points of preoperative radiographic parameters for selecting one-level PSO were: GK <94°, SVA <18.0 cm, and LL <18°. No significant difference was observed between the two groups with regard to preoperative ODI and VAS (P > 0.05), and the improvement of ODI and VAS (P > 0.05). Significantly more operative time, blood loss, and fusion levels were found in two-level PSO group (P < 0.05).

CONCLUSION

One-level PSO might be appropriate for selected severe AS-related kyphosis patients with GK <94°, SVA <18.0 cm, and LL <18°. This finding might be beneficial for surgical decision-making in performing one-level PSO, a relatively less risky procedure, to reconstruct the ideal sagittal alignment in AS patients with severe thoracolumbar kyphosis.Level of Evidence: 2.

Junctional Failure After Thoracolumbar Kyphosis Correction in Patients with Ankylosing Spondylitis

OBJECTIVE

We investigated the characteristics and revision rate of junctional failure after surgical correction for thoracolumbar kyphosis in patients with ankylosing spondylitis.

METHODS

A total of 230 patients had undergone surgical correction for thoracolumbar kyphosis from 2010 to 2019. The state of ankylosis between the uppermost instrumented vertebra (UIV) and UIV+1 and between the lowermost instrumented vertebra (LIV) and LIV-1 was analyzed using a modified Stoke ankylosing spondylitis spine score. Proximal junctional failure (PJF) and distal junctional failure (DJF) were defined as any type of symptomatic junctional failure.

RESULTS

Of the 230 patients, 23 (10.0%) had developed junctional failure. Of these 23 patients, 16 had had partial ankylosis and 7 had had complete ankylosis. PJF had developed in 10 patients and DJF in 13. The most common type of junctional failure was a junctional fracture, which developed in 12 patients. PJF had developed by UIV fracture in 4 patients, UIV+1 fracture in 1 patient, and UIV+2 in 1 patient. DJF had developed by LIV fracture in 6 patients, metallic failure in 5, and progression of DJF in 2 patients. The average time to the development of PJF and DJF was 13 months and 12.4 months, respectively. All 10 patients with PJF and 7 of 13 patients with DJF (53.8%) had required reoperation. Of the 12 patients with junctional fracture, 11 (91.7%) had undergone reoperation.

CONCLUSIONS

Of the 23 patients with junctional failure, 16 had had immature ossification of the anterior longitudinal ligament. Therefore, to prevent junctional failure, the state of ankylosis seems to be important for selecting the fusion level after osteotomy. Once junctional failure has developed, however, reoperation should be considered owing to the stress concentration at the UIV or LIV.

Mechanical revision following pedicle subtraction osteotomy: a competing risk survival analysis in 171 consecutive adult spinal deformity patients

STUDY DESIGN

Retrospective study.

OBJECTIVE

To report the incidence of revision surgery due to mechanical failure following pedicle subtraction osteotomy (PSO) in adult spinal deformity (ASD) patients. PSO allow major surgical correction of ASD, although; the risk of mechanical complications remains considerable. Previous reports have been based on smaller cohorts or multicenter databases and none have utilized competing risk (CR) survival analysis.

METHODS

All ASD patients undergoing PSO surgery from 2010 to 2015 at a single, tertiary institution were included. Demographics, long standing radiographs as well as intra- and postoperative complications were registered for all. A CR-model was used to estimate the incidence of revision surgery due to mechanical failure and two predefined multivariable models were used to assess radiographic prediction of failure and reported as odds ratios (OR) with 95% confidence intervals (95% CI).

RESULTS

A total of 171 patients were included with 2-year follow-up available for 91% (mean [IQR]: 35 [24-50] months). Mechanical failure occurred in 111 cases (65%) at any time in follow-up, the most frequent being rod breakage affecting 81 patients (47%). Cumulative incidence of revision surgery due to mechanical failure was estimated to 34% at 2 years and 58% at 5 years. A multivariable proportional odds model with death as competing risk showed significantly increased odds of revision with fusion to the sacrum (OR: 5.42; 95% CI 1.89-15.49) and preoperative pelvic tilt (PT) > 20° (OR: 2.41; 95% CI 1.13-5.16). History of previous surgery, number of instrumented vertebra, as well as postoperative SRS-Schwab modifiers and Global Alignment and Proportion score were not associated with significant effects on odds of revision.

CONCLUSIONS

In a consecutive single-center cohort of patients undergoing PSO for ASD, we found an estimated incidence of revision surgery due to mechanical failure of 34% 2 years postoperatively. Fusion to the sacrum and preoperative PT > 20° were associated with elevated risks of revision.

LEVEL OF EVIDENCE

Prognostic III.

Both structural damage and inflammation of the lumbar spine contribute to the sagittal imbalance in ankylosing spondylitis patients with thoracolumbar kyphosis

Background

The relationship between structural damage and inflammation of the spine and the sagittal imbalance in ankylosing spondylitis (AS) is not well understood. The present study aimed to investigate the correlation between structural damage and inflammation of the lumbar spine and the sagittal imbalance in AS patients with thoracolumbar kyphosis.

Methods

Forty-five AS patients with thoracolumbar kyphosis were retrospectively reviewed. Six sagittal spinal parameters, including the C7 tilt (C7T), spino-sacral angle (SSA), global kyphosis (GK), the sagittal vertical axis (SVA), thoracic kyphosis (TK), and lumbar lordosis (LL), were measured. Structural damage of the lumbar spine was assessed by the modified Stoke AS Spine Score (mSASSS) on radiographs. Lumbar spinal inflammation was evaluated by the AS spinal magnetic resonance imaging (MRI) activity (ASspiMRI-a) on MRI. Correlation analysis was performed using the paired sample t-test. Multivariable linear regression models were constructed to analyze the contributions of mSASSS and ASspiMRI-a to the sagittal parameters.

Results

The average values of the sagittal parameters C7T, SSA, GK, SVA, TK, and LL were 68.1°, 80.1°, 77.3°, 168.7 mm, 47.7°, and -0.7°, respectively. The average mSASSS and ASspiMRI-a scores were 9.8 and 10.8, respectively. Correlation analysis showed that the mSASSS and ASspiMRI-a were correlated with C7T, SSA, SVA, and LL (the Spearman correlation coefficients were -0.439, -0.390, 0.424, and 0.530 for mSASSS; -0.406, -0.402, 0.378, and 0.486 for ASspiMRI-a; P<0.05). The C7T, SSA, and SVA were significantly correlated with LL (r=-0.696, -0.779, and 0.633, respectively; P<0.05). There was a weak correlation between the mSASSS and ASspiMRI-a (β=0.299, P=0.046). The multivariable regression models indicated that the sagittal imbalance was determined to a greater extent by the mSASSS than ASspiMRI-a (the β values were -1.550 vs. -0.649 for C7T, -1.865 vs. -1.231 for SSA, 9.161 vs. 3.823 for SVA, and 3.128 vs. 1.717 for LL).

Conclusions

Both structural damage and inflammation of the lumbar spine contributed to the sagittal imbalance in AS patients with thoracolumbar kyphosis. In the late stages of AS, the sagittal imbalance was more attributable to the structural damage than the inflammation of the lumbar spine.

Surgical Treatment for Severe Fixed Hyperkyphosis in an Adult Patient Suffering From Ankylosing Spondylitis and Hereditary Hypophosphatemia With Vertebral Osteopetrosis

PURPOSE

Ankylosing spondylitis and hereditary hypophosphatemia with long-term high dose supplementation of phosphorous and calcitriol can both lead to severe structural abnormalities of the vertebrae. Impairment of spinal mobility and spinal deformity may ultimately necessitate surgical treatment. A severe fixed hyperkyphosis in a patient with ankylosing spondylitis is a surgically demanding condition, therefore, the indication for surgical treatment should be thoroughly considered and chosen individually.

METHODS

This is an uncommon case with a combination of a severe fixed hyperkyphosis with a Cobb-angle of 105 degrees between Th2 and L4 in an adult male patient suffering from ankylosing spondylitis and X-linked hypophosphatemia with surprisingly massive osteopetrosis. In this paper, the coexisting conditions of late-stage ankylosing spondylitis and long-term treated hereditary hypophosphatemia are highlighted. The surgical treatment with different techniques, complications, and results are well explained.

RESULTS

A normal gait and stand were achieved by a long posterior fusion with 3 pedicle subtraction osteotomies on L1, L3, and L5. The surgical correction was performed in 3 stages. Postoperative the patient was administered to a rehabilitation center for 3 months. The hyperkyphosis, the C7 plumbline, and the pelvic retroversion were corrected.

CONCLUSIONS

Surgical treatment of a severe fixed hyperkyphosis due to ankylosing spondylitis is technically demanding but can be successfully achieved if all surgical challenges and comorbidities are adequately addressed including intraoperative surprising findings like osteopetrotic bone in a patient with hereditary hypophosphatemia as in our case.

Radiographic findings for surgery-related complications after pedicle subtraction osteotomy for thoracolumbar kyphosis in 230 patients with ankylosing spondylitis

OBJECTIVE

The purpose of this study was to investigate the rate of and the risk factors for surgery-related complications demonstrated on radiography after pedicle subtraction osteotomy (PSO) for thoracolumbar kyphosis in patients with ankylosing spondylitis (AS).

METHODS

The authors retrospectively reviewed the medical records of 230 consecutive patients with thoracolumbar kyphosis due to AS who had undergone 1-level PSO at a single institution in the period from 2010 to 2017. The causes of surgery-related complications were divided into two types: surgical/technical failure and mechanical failure.

RESULTS

The patients consisted of 20 women and 210 men, with an average age of 43.4 years. The average follow-up period was 39.0 months. The preoperative sagittal vertical axis was 18.5 ± 69.3 cm, which improved to 4.9 ± 4.6 cm after PSO. Of the 77 patients (33.5%) who experienced minor or major surgery-related complications, 56 had complications related to surgical/technical failure (overall incidence 24.3%) and 21 had complications related to mechanical failure (overall incidence 9.1%). Fourteen patients (6.1%) underwent reoperation. However, among the 77 patients with complications, the rate of revision surgery was 18.2%. The most common radiological complications were as follows: sagittal translation in 24 patients, coronal imbalance in 20, under-correction in 8, delayed union in 8, and distal junctional failure and kyphosis in 8. The most common causes of reoperation were coronal imbalance in 4 patients, symptomatic malposition of pedicle screws in 3, and distal junctional failure in 3. Delayed union was statistically correlated with posterior sagittal translation (p = 0.007).

CONCLUSIONS

PSO can provide acceptable radiographic outcomes for the correction of thoracolumbar kyphosis in patients with AS. However, a high incidence of surgery-related complications related to mechanical failure and surgical technique can develop. Thorough radiographic investigation before and during surgery is needed to determine whether complete ossification occurs along the anterior and posterior longitudinal ligaments of the spine.

Effects of Andersson lesion treatment in ankylosing spondylitis: A medical record review study focused on medium- to long-term outcomes

The present study aimed to evaluate the clinical efficacy of Andersson lesion (AL) treatments and prognostic factors using medium- to long-term follow-up data and discuss the clinical characteristics and treatment of AL. Forty-eight consecutive AL cases at our center from June 2011 to March 2018 were retrospectively analyzed, including 13 cases treated conservatively and 35 treated surgically. Epidemiological characteristics, treatment modalities, clinical features and outcomes, and prognostic factors of the Japanese Orthopaedic Association (JOA) recovery rate were reviewed. Neurological functional recovery was evaluated by American Spinal Injury Association (ASIA) classification. Clinical efficacy was evaluated by JOA score, visual analog scale (VAS) score, and Cobb's angle. The mean overall follow-up duration was 44.5±18.5 months (range, 27-85 months). There were 36 male and 12 female patients, with a mean age of 49.4±13.1 years (range, 26-72 years). The most common lesion location was the thoracolumbar region, i.e., T10-L2 (n=33; 68.8%), followed by the thoracic (n=10) and lumbar (n=5) regions. Patients treated surgically showed significantly better JOA scores, VAS scores and Cobb's angles at the final follow-up than did patients treated conservatively (P<.05). Univariate and binary logistic regression analyses identified two prognostic factors of the JOA score recovery rate: treatment modality (OR=0.157; 95%CI, 0.028-0.89; P=.036) and bone fusion (OR=9.965; 95%CI, 2.052-48.387; P=.004). Conservative treatment and bone nonunion predict worse JOA score recovery. Surgery remains the optimal treatment for AL in ankylosing spondylitis patients, with better clinical efficacy demonstrated by medium- to long-term follow-up data.

Systemic changes associated with quality of life after surgical treatment of kyphotic deformity in patients with ankylosing spondylitis: a systematic review

PURPOSE

In addition to changes in the skeletal system after spinal osteotomy for treatment of kyphotic deformity in advanced-stage AS patients, many other systemic changes associated with the patients' quality of life were reported. The purpose of this study was to conduct a systemic review of the literature to determine systemic changes associated with patients' quality of life following correction of kyphotic deformity secondary to ankylosing spondylitis.

METHODS

We searched the databases PubMed, EMBASE, Clinicalkey and Cochrane Library without time restriction. Selected papers were assessed by published guidelines. We investigated systemic changes associated with patients' quality of life after surgical treatment of advanced ankylosing spondylitis.

RESULTS

The initial search yielded 888 citations. Twelve of these studies met the inclusion and exclusion criteria. Two were level II evidence study, and ten were level III evidence studies. Changes were reported including aorta length, abdominal morphology, digestive function, cardiopulmonary function, psychological status, and sexual activity.

CONCLUSIONS

In addition to skeletal changes after spinal osteotomy for treatment of kyphotic deformity in advanced-stage AS patients, many other changes were reported. Spine surgeons should pay more attention to these life quality-related changes and be aware of potential risks when performing surgery for advanced-stage AS patients. These slides can be retrieved under Electronic Supplementary Material.

Combined percutaneous and open instrumentation for thoracolumbar kyphosis correction by two-level pedicle subtraction osteotomy in ankylosing spondylitis

BACKGROUND

A long global thoracolumbar kyphosis is common in ankylosing spondylitis. Surgical correction of fixed sagittal malalignment by pedicle subtraction osteotomy (PSO) might improve disability and quality of life (QoL). Two-level osteotomies represent major procedures with a risk of hemorrhage. Combined open and minimal invasive surgery has not been described and might be considered.

CASE PRESENTATION

A 30-year-old female with ankylosing spondylitis was treated by golimumab and teriparatide. The treatment was stopped during pregnancy which led to vertebral compression fractures and kyphosis of 50° between T11 and L3. A PSO was planned at the kyphotic apex L2. The second PSO was planned at L4 according to the pelvic incidence of 56°, matching with a spinopelvic alignment Roussouly type 3. A derived full balance integrated method was used to calculate the amount of correction. During the first stage surgery, an open approach was performed from L1 to pelvis and combined with percutaneous cement-augmented instrumentation in already fused segments T5-T12, thus reducing perioperative morbidity. A stepwise approach including L2 PSO closure with temporary rods and L4 PSO with final instrumentation was used. Blood loss was estimated around 1100 ml. The patient was able to walk on the second day after surgery. A secondary anterior fusion with LLI cages from L2 to L5 and an ALIF at L5-S1 were performed because of high non-ossified intervertebral disks to reduce the risk for nonunion and rod fractures. At 2-year follow-up, the patient's QoL had significantly improved and full spine radiographs showed stable normalized sagittal parameters.

CONCLUSION

The combined open and percutaneous approach was feasible and might be considered as an alternative option to conventional open surgery when planning major deformity correction in ankylosing spondylitis.

[Debridement and interbody fusion via posterior pedicle lateral approach for ankylosing spondylitis with thoracolumbar Andersson lesion]

Objective

To investigate the safety and effectiveness of debridement and interbody fusion via posterior pedicle lateral approach in treatment of ankylosing spondylitis with thoracolumbar Andersson lesion (AL).

Methods

Between October 2011 and January 2017, 10 patients of ankylosing spondylitis with thoracolumbar AL were treated with debridement via posterior pedicle lateral approach and interbody fusion with bone grafting. There were 8 males and 2 females with an average age of 48.8 years (range, 31-79 years). The disease duration was 1.5-48.0 months (mean, 10.6 months). All patients were single-segment lesion, including 3 cases of T_{10, 11}, 4 cases of T_{11, 12}, and 3 cases of T₁₂, L₁. The preoperative visual analogue scale (VAS) score was 8.0±0.8, the Oswestry disability index (ODI) was 68.8%±5.5%, and the Cobb angle of local kyphosis was (26.3±7.1)°. According to American Spinal Injury Association (ASIA) scoring system, neurological impairment was assessed in 1 case of grade C, 4 cases of grade D, and 5 cases of grade E.

Results

All the operations of 10 patients completed successfully. The operation time was 120-185 minutes (mean, 151.5 minutes), and the intraoperative blood loss was 300-750 mL (mean, 450.0 mL). Dural sac tear occurred in 1 case during operation and was repaired, with no cerebrospinal fluid leakage after operation. All patients were followed up 24-50 months (mean, 31.2 months). At last follow-up, the VAS score was 1.9±0.9 and ODI was 13.0%±3.0%, showing significant differences when compared with preoperative ones (t=17.530, P=0.000; t=31.890, P=0.000). Neurological function was improved significantly at 24 months after operation, and rated as ASIA grade E. The Cobb angles were (12.6±4.6)° at 3 days and (13.6±4.6)° at 24 months after operation, which were significantly different from those before operation (P<0.05); there was no significant difference between 3 days and 24 months after operation (P>0.05). At 24 months after operation, the grafted bone obtained good fusion at AL segment. During the follow-up, there was no failure of internal fixation such as nail withdrawal, broken nail, and broken rod.

Conclusion

Debridement and interbody fusion via posterior pedicle lateral approach for the ankylosing spondylitis with thoracolumbar AL can achieve satisfactory effectiveness, good fusion, and a certain correction of local kyphosis.

Full-spine radiographs: what others are reporting-a survey of Society of Skeletal Radiology members

OBJECTIVE

Full-spine radiographs are frequently ordered by spinal deformity surgeons to assess spinal imbalance. The radiologist interpretation of these films varies amongst providers. Detailed numeric measurements of the deformity are time-consuming. In this study, we hoped to better define current practice patterns for interpretation of spinal deformity films amongst musculoskeletal radiologists in North America.

MATERIALS AND METHODS

An anonymous online survey was conducted amongst Society of Skeletal Radiology members.

RESULTS

Only 26.5% of respondents (n = 57) routinely report pelvic tilt, 23.2% (n = 52) for sagittal vertical axis and 5.1% (n = 11) for Pelvic Incidence Lumbar Lordosis mismatch in adult spinal deformity. Furthermore, the majority of musculoskeletal radiologists (84.96%) dictate the same type of report for both adult and pediatric cases.

CONCLUSIONS

The majority (n = 199, 70%) of 283 respondents state that no institutional standard template for full-spine dictations exists. The development of such templates listing appropriate parameters to include in the dictation may be useful in order to ensure that the radiologist's effort and clinical utility for the ordering provider are optimized.

Clinical results and surgery tactics of spinal osteotomy for ankylosing spondylitis kyphosis: experience of 428 patients

OBJECTIVE

To report the clinical results and surgical tactics of spinal osteotomy for ankylosing spondylitis (AS) kyphosis based on the experiences of 428 patients.

METHODS

From January 2003 to January 2015, a total of 428 patients suffering from AS kyphosis who underwent a one- or two-level pedicle subtraction osteotomy (PSO) or vertebral column decancellation (VCD) osteotomy in our hospital were reviewed. Pre- and postoperative radiological parameters and the chin-brow vertical angle (CBVA) were measured. Intraoperative, postoperative, and general complications were recorded.

RESULTS

All patients could walk with horizontal vision and lie on their backs postoperatively. The pre- and postoperative average global kyphosis (GK) angles were corrected from 82.6 to 12.7° (p = 0.000) in the two-level group and from 55.8 to 9.6° (p = 0.000) in the one-level group, respectively. The mean sagittal vertical axis (SVA) improved from 29.4 to 8 cm (p = 0.000) in the two-level group and from 18.0 to 4.3 cm (p = 0.000) in the one-level group. The CBVA improved from 68.3 to 8.2° (p = 0.000) in the two-level group and from 46.2 to 4.2° (p = 0.000) in the one-level group. Although no major acute complications such as death or complete paralysis occurred, the complication rate was 6.5% in the one-level group and 23.6% in the two-level group.

CONCLUSION

Spinal osteotomy, such as PSO and VCD, can improve the quality of life of AS patients as well as correct kyphotic deformities. The one-level spinal osteotomy showed a lower complication rate, while two-level spinal osteotomy was a relatively aggressive procedure that was more suitable in correcting severe AS kyphotic deformities.

Ankylosing spondylitis: etiology, pathogenesis, and treatments

Ankylosing spondylitis (AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain; additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis. However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.

Two-Level Osteotomy for Correcting Severe Ankylosing Spondylitis Kyphosis: Radiologic Outcomes of Different Osteotomy Position-Selection Strategy for Different Type of Patients

OBJECTIVE

To report on the radiologic outcomes of different osteotomy position-selection strategies for a two-level osteotomy for correcting severe ankylosing spondylitis kyphosis.

METHODS

From July 2009 to September 2016, a total of 46 patients in our department with severe ankylosing spondylitis kyphosis who underwent two-level pedicle subtraction osteotomy (PSO) were studied. Pre- and postoperative relevant parameters were recorded. The patients were divided into two types and further separated into four groups. The lumbar lordotic angle of Type I patients was larger than or equal to 0°. The lumbar lordotic angle of Type II patients was less than 0°. The patients of Group I belonging to Type I underwent superior spinal osteotomy at the L1 vertebra. The patients of Group II belonging to Type I underwent superior spinal osteotomy at the T12 vertebra. The patients of Group III belonging to Type II underwent superior spinal osteotomy at the L1 vertebra. The patients of Group IV belonging to Type II underwent superior spinal osteotomy at the T12 vertebra.

RESULTS

Analysis of preoperative data showed that the lumbar lordosis (LL) of Group I and II patients was significantly larger than those of Group III and IV. Postoperative data analysis showed that there was significant difference among the four groups in the postoperative LL and TK. The LL of Group II and III patients was smaller than that of Group I patients, and was larger than that of Group IV patients. Group II and Group III patients had more moderate LL and better physiological curvature than those in Group I and Group IV. There were no significant differences between Group II and Group III patients in postoperative LL, thoracolumbar kyphosis, thoracic kyphosis, and global kyphosis. And, likewise, there were no significant differences among the four groups in cervical 7 sacrum angle (C7SA).

CONCLUSION

Two-level osteotomy was effective for correcting severe ankylosing spondylitis kyphosis. In patients with LL greater than or equal to 0°, it would be better if the second or superior spinal osteotomy was performed at T12 rather than at L1 for restoring the sagittal balance. In patients with LL smaller than 0°, it would be more satisfactory to perform two-level osteotomy at lumbar vertebras for correcting sagittal imbalance.

LEVEL OF EVIDENCE

Level III.

Proposal of a New Treatment-Oriented Classification System for Spinal Deformity in Ankylosing Spondylitis

OBJECTIVE

To describe and apply an optimal classification system for the management of ankylosing spondylitis (AS) that may be appropriate to make a preoperative surgical plan.

BACKGROUND

The treatment choices of ankylosing spondylitis kyphosis remain controversial. The lack of a widely accepted classification system contributes to the variation in surgical decision making.

METHODS

The classification is mainly based on radiographic findings. The sagittal deformity of spine in ankylosing spondylitis is classified according to three criteria: the location of the apex, the lumbar modifier (A, lumbar lordosis <0°, and B, lumbar kyphosis >0°) and the thoracic/thoracolumbar kyphosis severity modifier (- or +).

RESULTS

The ankylosing spondylitis kyphosis can be divided into 4 types according to the location of the apex: Type I (lumbar), Type II (thoracolumbar), Type III (thoracic), Type IV (cervical or cervicothoracic junction). Either Type II or Type III is further divided into four subtypes based on the lumbar modifier and the thoracic/thoracolumbar kyphosis severity modifier: Type IIA-, Type IIA+, Type IIB-, Type IIB+, Type IIIA-, Type IIIA+, Type IIIB-, and Type IIIB+. Surgical decision making for AS kyphosis can be made according to the new classification.

CONCLUSION

This new classification system can be used effectively to classify AS kyphosis, which can be used to guide surgical decision making, including determining the site and the levels of osteotomies. Further research may be needed to validate the classification.

Radiological morphology variances of osteotomized vertebra-disc complex following pedicle subtraction osteotomy for ankylosing spondylitis with thoracolumbar kyphosis: the incidence, mechanisms, and prognosis

BACKGROUND CONTEXT

Inaccurate osteotomy cut along with incomplete or even subluxated bone-on-bone closure of osteotomy gap following pedicle subtraction osteotomy (PSO) may be disastrous, hampering the lordosing effect and increasing the likelihood of complications. The inelastic yet osteoporotic spine in ankylosing spondylitis (AS) is specially predisposed to such suboptimal osteotomy, while the relevant data concerning this issue are scarce.

PURPOSE

This study aimed to analyze the incidence of radiological morphology variances (RMV) of osteotomized vertebra-disc complex (OVDC) following PSO in patients with kyphotic AS, conceptualize the mechanisms of the deviated morphology, and investigate the prognosis.

STUDY DESIGN

This is a retrospective radiological data analysis.

PATIENT SAMPLE

The sample being screened comprises 71 patients with thoracolumbar kyphotic AS who underwent single-level PSO at our hospital between March 2006 and February 2014. They were stratified by the presence of bridging syndesmophytes (BS) locating within the OVDC.

OUTCOME MEASURES

Any irregular radiological configuration of OVDC other than the wedge morphology would be considered as RMV and were studied with care to fully describe and classify the spectrum of deviated morphologic features. Multiple spinopelvic sagittal parameters were measured to assess both the regional lordosing effect and the global realignment of sagittal spinal profile.

METHODS

For each selected patient with confirmed RMV, the radiological morphology was assessed, defined, and categorized. The prognosis involving surgical corrections and maintenance of spinopelvic sagittal parameters, as well as the remodeling in disordered osteotomized vertebral shape over time, were also investigated.

RESULTS

The incidence of RMV was 21.9% in positive BS group (PG) and 30.8% in negative BS group (NG). Inappropriate angle and range of osteotomy accounted for the largest share (1 pts for PG and 10 pts for NG, 57.9%) of mechanisms responsible for RMV, followed by vertebral subluxation (VS) (5 pts for PG and 2 pts for NG, 36.8%) and failed osteotomy gap closure (1 pts for PG, 5.3%). For these patients, the mean bony lordosing effect per PSO segment was 36.0°±8.9° postoperatively, and decreased to 34.7°±8.7° by a mean follow-up of 3 years (p=.076). The magnitude of neighboring disc opening was significantly higher in NG (10.2°±6.5° vs. 2.4°±3.2°, p=.009). The global kyphosis and sagittal vertical axis were significantly corrected (77.0°±21.2° vs. 24.4°±18.8°; 160.6°±72.4° vs. 48.2°±38.6 mm, all p<.001) and remained stable by the ultimate follow-up (p>.05). No devastating neurologic deficits were noticed. Patients with VS and failed osteotomy gap closure exclusively showed solid bone healing and adaptive remodeling without rod breakage at final follow-up.

CONCLUSIONS

Radiological morphology variances of OVDC were a high occurrence following PSO in AS, being mainly attributed to inaccurate osteotomy cut and VS. Neighboring disc opening and rotational or translational subluxation were major available remedial mechanisms strengthening the lordosing effect when that of vertebral wedging was impaired and insufficient. The bone fusion and remodeling concerning the subluxated or dislocated osteotomized vertebra was utterly favorable, maintaining the kyphosis correction and preventing instrumentation failure.

Does the preoperative lumbar sagittal profile affect the selection of osteotomy level in pedicle subtraction osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis?

OBJECTIVE

To investigate the different preoperative lumbar sagittal profiles of ankylosing spondylitis (AS) patients and the selection of osteotomy level for one-level pedicle subtraction osteotomy (PSO) for the correction of thoracolumbar kyphosis.

PATIENTS AND METHODS

Seventy-one consecutive AS patients with an average age of 35.3 years and a mean follow-up time of 35.9 months who underwent one-level PSO for thoracolumbar kyphosis were divided into 2 groups based on their preoperative lumbar sagittal profiles as follows: group A, lordotic lumbar sagittal profiles; and group B, kyphotic lumbar sagittal profiles. The following radiological parameters were measured and compared: chin-brow vertical angle (CBVA), global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). Clinical evaluation included Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS). Perioperative and mid-term complications were reviewed.

RESULTS

There were 28 patients in group A and 43 in group B. The preoperative LL was -21.0° in group A and 2.3° in group B (P < 0.05). The preoperative SVA was 122.5 mm in group A and 184.3 mm in group B (P < 0.05). All the patients in group A (100%) underwent PSO at L1/L2, while 90% of group B patients underwent PSO at L2/L3, with no significant difference of postoperative GK, LL and SVA between the 2 groups (P > 0.05). No obvious loss of correction was observed in either group at the final follow-up. The correction of LL and SVA showed a strong but not statistically significant increasing trend as the PSO level descended from L1 to L3 (P > 0.05). The postoperative ODI was significantly lower in patients underwent PSO at L1 or L2 (P < 0.05).

CONCLUSIONS

Patients in group B had significantly worse preoperative sagittal alignments compared to group A. The distribution of osteotomy levels varied between the 2 groups due to the different lumbar profiles; however, satisfactory correction was achieved in both groups. The preoperative lumbar profiles need to be considered in selecting the optimal osteotomy level. Patients with kyphotic lumbar profiles are suitable candidates for PSO at L2/L3, while L1/L2 PSO is appropriate for patients with lordotic lumbar profiles.

Optimizing Pedicle Subtraction Osteotomy Techniques: A New Reduction Plier to Increase Technical Safety and Angular Reduction Efficiency

BACKGROUND

Pedicle subtraction osteotomy (PSO) is a technically demanding surgery. There is room for development of osteotomy reduction instruments like the one we present in this study, to better guide angular correction and closure of the osteotomy line.

OBJECTIVE

To present a new surgical instrument that optimizes PSOs of the thoracolumbar spine.

METHODS

Seventeen consecutive patients have been treated at 3 different European University Hospitals. All underwent a PSO of the lumbar spine to treat major sagittal imbalance. The amount of vertebral angular correction needed was calculated using the full balance integrated (FBI) method. A special plier, which allows to safely control the angular correction, was used intraoperatively. Preoperative and early postoperative global sagittal balance parameters were compared.

RESULTS

The mean preoperative calculated correction angle (FBI) was 33.8°; the mean postoperative correction obtained was 32.1°. Lumbar lordosis was statistically greater than preoperatively (55.8° vs 19.4°, P &lt; .0001). The global sagittal balance was improved, as shown by the increase of the spino-sacral angle from 122° preoperatively to 128° postoperatively (P = .0547). None of the patients had an intraoperative or early postoperative neurologic complication. There were no mechanical intraoperative complications during correction nor at the first postoperative follow-up.

CONCLUSION

The advantages of the instrument are safe, precise, and efficient reduction, by a rotation of the pedicle screws close to the osteotomy line, thus avoiding collapse and lack of correction, complications usually seen with the conventional technique. Further prospective studies are needed to confirm these results.

The clinical relevance of the presence of bridging syndesmophytes on kyphosis correction and maintenance following pedicle subtraction osteotomy for thoracolumbar kyphotic deformity in ankylosing spondylitis: a comparative cohort study

Background

The presence of bridging syndesmophytes (BS) in spinal osteotomy region serves traditionally as one critical determinant for selection of osteotomy techniques. While nowadays the proportion of kyphotic ankylosing spondylitis (AS) patients receiving pedicle subtraction osteotomy (PSO) with yet mobile neighboring disc has seen a substantial increase. Literatures investigating the clinical relevance of the presence of BS on kyphosis correction and maintenance following PSO are scarce.

Methods

A total of 71 thoracolumbar kyphotic AS patients treated with single-level PSO at our hospital between September 2010 and August 2014 were retrospectively reviewed, 32 of whom were stratified into the BS group (BG). The operative corrections of multiple spino-pelvic sagittal parameters were assessed. Comparison of the contribution of adjacent disc wedging to total correction per PSO segment was made between the BS and non-BS groups (NBG). The correction loss were also evaluated and compared with a minimum 2-year follow-up.

Results

A significantly younger age (30.97 ± 8.28 vs. 40.31 ± 8.44 yrs., p < 0.001), smaller pelvic incidence (PI) (43.03 ± 10.60 vs. 49.36 ± 9.75°, p = 0.011), greater wedging index of osteotomized vertebra (1.17 ± 0.16 vs. 1.09 ± 0.08, p = 0.011) and larger local kyphosis (19.59 ± 10.84 vs. 13.56 ± 8.50°, p = 0.013) was observed in NBG preoperatively. Patients in BG and NBG accomplished comparable amount of kyphosis correction per PSO segment (40.22 ± 7.09 vs. 43.85 ± 8.71°, p = 0.062). However, the contribution of adjacent disc wedging to total correction per PSO was significantly larger in NBG [8.10 ± 6.19 (18.5%) vs. 1.09 ± 2.88° (2.7%), p < 0.001]. By ultimate follow-up, the global kyphosis (18.26 ± 10.97 vs. 21.51 ± 10.89°, p < 0.05) and thoracic kyphosis (37.95 ± 11.87 vs. 42.87 ± 11.56°, p < 0.05) deteriorated significantly in the NBG but not BG, so was further pelvic retroversion as represented by increased pelvic tilt (19.46 ± 8.13 vs. 23.44 ± 8.19°, p < 0.05) and decreased sacral slope (23.02 ± 9.12 vs. 18.62 ± 10.10°, p < 0.05). Loss of corrections concerning contribution of adjacent disc wedging was also larger in NBG (1.41 ± 3.27 vs. 0.22 ± 1.49°, p < 0.05).

Conclusions

Our study might suggest that the evaluation and treatment methods of kyphotic AS patients needed to be fine-tuned with appropriate subgrouping by the presence of syndesmophytes with bamboo sign as they were potentially distinct groups with different PI, contributor of lordosing capability and prognosis that might require separate analysis.

Alphabet Soup: Sagittal Balance Correction Osteotomies of the Spine-What Radiologists Should Know

Global sagittal malalignment has been demonstrated to have correlation with clinical symptoms and is a key component to be restored in adult spinal deformity. In this article, various types of sagittal balance-correction osteotomies are reviewed primarily on the basis of the 3 most commonly used procedures: Smith-Petersen osteotomy, pedicle subtraction osteotomy, and vertebral column resection. Familiarity with the expected imaging appearance and commonly encountered complications seen on postoperative imaging studies following correction osteotomies is crucial for accurate image interpretation.

Pedicle Subtraction Osteotomy with a Cage Prevents Sagittal Translation in the Correction of Kyphosis in Ankylosing Spondylitis

BACKGROUND

Sagittal translation (ST) is an accidental event that surgeons commonly encounter during a spinal osteotomy in the correction of kyphosis in ankylosing spondylitis (AS). However, there is a paucity of effective techniques to prevent ST. The purpose of this study was to propose a pedicle subtraction osteotomy (PSO) with a cage as a method to prevent ST and to explore the efficacy and feasibility of this method in the treatment of kyphosis in AS.

METHODS

We retrospectively reviewed 89 consecutive patients with AS kyphosis who underwent a PSO (Group B, 46 patients) or a PSO with a cage (Group A, 43 patients) from February 2009 to December 2013. Pre- and post-operative radiographic results were reviewed. ST and complications were analyzed in both groups. Clinical assessment was performed using the Scoliosis Research Society-22 (SRS-22) outcomes metric. The patients were followed up for at least 2 years.

RESULTS

Group A achieved the same re-alignment of the kyphotic spine as Group B. Two (4.7%) of the 43 patients in Group A and 14 (30.4%) of the 46 patients in Group B had intraoperative ST (χ2 = 10.020, P = 0.002). Significant differences were identified between the two groups in the height change of the osteotomized column. SRS-22 scores improved significantly in both groups. Seven patients experienced neurologic complications (1 in Group A and 6 in Group B). Eight patients had cerebrospinal fluid leakage (2 in Group A and 6 in Group B).

CONCLUSION

PSO with a cage significantly avoided ST during the osteotomy procedure and might represent a new, safe, and feasible choice for treating patients with AS kyphosis.

The patterns of loss of correction after posterior wedge osteotomy in ankylosing spondylitis-related thoracolumbar kyphosis: a minimum of five-year follow-up

BACKGROUND

Short-term studies have demonstrated good surgical outcomes after pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients, but there is a paucity of literature focused on middle-term results, especially regarding patterns of loss of correction. The objective of this study is to assess the durability of surgical outcomes and the patterns of loss of correction in thoracolumbar kyphosis secondary to AS following lumbar PSO with over 5-year follow-up.

METHODS

We performed a retrospective review of 155 consecutive AS patients undergoing lumbar PSO from January 2001 to December 2011. Twenty-four patients were included with an average follow-up of 6.9 years (range, 5-15 years). Radiographical evaluations included global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis, spinal-sacral angle, kyphosis of proximal non-fused segments (KPNS), angle of fused segments (AFS), osteotomized vertebra angle (OVA), distal intervertebral disc wedging (DIDW) and proximal junctional angle. Meanwhile, clinical outcomes were assessed by the Oswestry disability index (ODI) and Numerical rating scale (NRS).

RESULTS

The average correction per PSO segment was 34.9°. Significant improvement in sagittal parameters were found postoperatively, and no obvious deterioration was noticed during the follow-up. Mild loss of correction in GK (2.82°) and LL (3.77°) were observed at the final follow-up (P < 0.05). The KPNS and DIDW increased from 26° and -5.0° postoperatively to 30° and -2.2° at the final follow-up (P < 0.05), respectively. In contrast, no significant diminishment was identified in OVA and AFS (P > 0.05). The ODI and NRS improved significantly from 20.6 and 6.6 preoperatively to 5.9 and 2.3 at the final follow-up (P < 0.05).

CONCLUSIONS

PSO is an effective procedure for treating AS-related thoracolumbar kyphosis and can maintain sustained surgical outcomes during the middle-term follow-up. The loss of correction was mainly attributable to non-instrumented segments without fully ossified bridging syndesmophyte in the thoracolumbar region instead of instrumented levels.

Mechanisms, Predisposing Factors, and Prognosis of Intraoperative Vertebral Subluxation During Pedicle Subtraction Osteotomy in Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis

STUDY DESIGN

A retrospective study.

OBJECTIVE

To analyze the mechanisms, predisposing factors, and prognosis of the intraoperative vertebral subluxation (VS) during pedicle subtraction osteotomy (PSO) for thoracolumbar kyphosis secondary to ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA

VS is one of the most daunting challenges that surgeons encounter during PSO closure, especially in patients with AS with ankylosed and mostly osteoporotic spine. Unfortunately, there is a paucity of research designed to conceptualize the mechanisms, predisposing factors, and discuss the complication-avoidance strategies and prognosis.

METHODS

A retrospective single-center review was performed for a consecutive series of 153 patients with AS with rigid thoracolumbar kyphosis who underwent one-level PSO from April 2000 to December 2013. The incidence of the VS at the level of PSO during correction was analyzed and the potential causative factors were investigated.

RESULTS

VS occurred in six patients with the incidence being 3.9% in this patient cohort. The predisposing factors were (1) early fracture of the anterior cortex of the osteotomized vertebra (OV); (2) excessive decancellation from vertebral body causing parallel collapse of the vertebral column with significant loss of the ability to create local lordosis; (3) improper manual osteoclasis due to insufficient decancellation of the OV; and (4) inappropriate application of cantilever technique and concomitant long instrumentation. The early surgical complication involved one patient with cerebrospinal fluid leakage at the osteotomized site, but no devastating neurological deficits. During follow-up, bone healing and adaptive vertebral remodeling with no rod breakage were observed for all these six patients.

CONCLUSION

Intraoperative VS was a rare occurrence associated with inappropriate manual manipulation of osteotomy, gap closure, and rod insertion. Neurological complication was a potential risk, but could be well prevented with extensive laminectomy and emergency actions favoring partial subluxation reduction. Moreover, adaptive bone remodeling and fusion at the level of VS ensured the maintenance of kyphosis correction and avoidance of instrumentation failure.

LEVEL OF EVIDENCE

4.

The Safe Correction Angle of Osteotomy at T12 and L1 for Ankylosing Spondylitis Kyphosis: Patients With 2-level Osteotomy

STUDY DESIGN

This is a retrospective clinical study.

OBJECTIVE

To investigate the correction angle and safety of the spinal osteotomy at the T12 or L1 vertebra.

SUMMARY OF BACKGROUND DATE

Monosegment subtraction osteotomy cannot effectively correct severe kyphosis in ankylosing spondylitis (AS), generally 2-level spinal osteotomy was taken for achieving expected correction. According to literature, the T12 or L1 were usually taken as the upper spinal osteotomy vertebra. Because of the canalis vertebralis at the T12 and L1 were spinal cord and medullary cone, so the spinal osteotomy at the T12 or L1 vertebra were more dangerous than at lower level. The correction angle and safety of the spinal osteotomy at the T12 or L1 vertebra have not yet been reported.

MATERIALS AND METHODS

From July 2009 to 2014, 33 patients in our department with severe AS kyphosis underwent 2-level pedicle subtraction osteotomy were studied. Preoperative and postoperative relevant parameters and complications were recorded.

RESULTS

The upper spinal osteotomy was taken at the T12 vertebra for 10 patients. The upper spinal osteotomy was taken at the L1 vertebra for 23 patients. The mean amount of correction of T12 and L1 was 26.230 and 27.952 degrees, respectively. All patients could walk with orthophoria and lie horizontally postoperatively. No deadly vascular and neurological lesion occurred.

CONCLUSIONS

Performing pedicle subtraction osteotomy at T12 and L1 can safely achieve a mean correction of 26.230 and 27.952 degrees, respectively. Two-level osteotomy was safely and advocated for correcting severe AS kyphosis.

LEVEL OF EVIDENCE

Level III.

Does the Position of the Aorta Change With the Altered Body Position in Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis?: A Magnetic Resonance Imaging Investigation

STUDY DESIGN

A prospective magnetic resonance imaging study.

OBJECTIVE

To quantitatively explore the differences in the anatomic position of the aorta relative to the spine between supine and prone positions in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis.

SUMMARY OF BACKGROUND DATA

Aortic complications may occur during the lumbar spine osteotomy in correcting thoracolumbar kyphosis secondary to AS, and a clear understanding of the spatial relationship between the aorta and the vertebrae is essential to prevent these iatrogenic complications. However, previous anatomic study was performed with AS patients in the supine position, which was different from the prone position adopted in surgery. To date, no report has been published to investigate the mobility of the aorta relative to the vertebrae between supine and prone positions in AS patients with thoracolumbar kyphosis.

MATERIALS AND METHODS

From March 2013 to September 2014, 22 AS patients (21 males, 1 female) with thoracolumbar kyphosis with a mean age of 30.7 years (range, 19-46 y) were recruited. Magnetic resonance imaging examinations from T9 to L3 in both the supine and prone positions were performed, and the left pedicle-aorta (LtP-Ao) angle and LtP-Ao distance were measured at each level. The differences of these parameters between the 2 positions were compared by the paired sample t test, and the relationships between the shifting of the aorta and the change of global kyphosis and lumbar lordosis were evaluated by the Pearson correlation coefficient. The level of significance (α) was set at 0.05.

RESULTS

At T9-L3 levels, no significant difference was noted in LtP-Ao distances (43.78 vs. 44.42 mm; P=0.077) and LtP-Ao angles (0.82 vs. 0.22 degrees; P=0.053) between supine and prone positions. The correlation analysis also revealed no remarkable correlation between the change of LtP-Ao angle and increase of global kyphosis and lumbar lordosis in the prone position.

CONCLUSIONS

There is no significant change of the relative positions between the aorta and the vertebrae at T9-L3 levels after the patient turned to a prone position, which implied that the mobility and range of motion of the aorta is limited in advanced stage of AS.

Analysis of Sagittal Parameters in Patients Undergoing One- or Two-Level Closing Wedge Osteotomy for Correcting Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis

STUDY DESIGN

Retrospective analysis of clinical records.

OBJECTIVE

To assess and compare the improvement in sagittal balance after one- or two-level closing wedge osteotomy for correcting thoracolumbar kyphosis secondary to ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA

Closing wedge osteotomy represents a common approach to correct kyphosis in AS. Although several reports have described the outcomes of one- or two-level closing wedge osteotomy in terms of sagittal parameters, data comparing the outcomes of these procedures are scarce.

METHODS

Between January 2010 and December 2014, 22 patients with AS underwent closing wedge osteotomy (one-level, 12 patients; two-level, 10 patients) for correcting thoracolumbar kyphosis (mean follow-up, 24.8 months; range, 12-60 months). Preoperative and postoperative chin-brow vertical angle, and the sagittal parameters of the vertebral osteotomy segment were documented and compared. Perioperative and postoperative complications were also recorded.

RESULTS

The chin-brow vertical angle improved significantly, from 55.0° ± 27.3° to 4.7° ± 4.9° and from 38.2° ± 14.9° to 3.2° ± 5.4° in the one-level and two-level groups, respectively. The total correction (thoracic kyphosis and lumbar lordosis) was 32.8° ± 18.2° and 53.7° ± 9.4° in the one-level and two-level groups, respectively. No death, complete paralysis, or vascular complications occurred during the procedure, but cerebrospinal fluid leak was noted in one and two patients from the one-level and two-level groups, respectively. A distal pedicle screw adjacent to the osteotomy segment became loose during surgery in one patient (one-level group). Postoperatively, no transient neurological deficit, infection, delay union, or loosening or breaking of the internal fixation devices was observed. Osteotomy site fusion was achieved in all patients, and the Oswestry Disability Index scores improved significantly.

CONCLUSION

Closing wedge osteotomy is effective and safe for correcting thoracolumbar kyphosis in patients with AS. Significant correction and improvement in all sagittal parameters were noted in both groups, but two-level closing wedge osteotomy provided better correction.

LEVEL OF EVIDENCE

3.

Effect and Strategy of 1-stage Interrupted 2-level Transpedicular Wedge Osteotomy for Correcting Severe Kyphotic Deformities in Ankylosing Spondylitis

STUDY DESIGN

Prospective study.

OBJECTIVE

To investigate the safety, outcome, and strategy of the 1-stage interrupted 2-level transpedicular wedge osteotomy for correcting the severe kyphotic deformity in ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA

There has been a large series in the literature reporting on results of osteotomy for the correction of kyphotic deformity secondary to AS. However, few articles have reported, in detail, the plan, design, strategy, and effect of 1-stage interrupted 2-level transpedicular wedge osteotomy for the correction of severe kyphotic deformity in AS.

MATERIALS AND METHODS

From May 2003 to February 2010, 24 consecutive patients, 17 males and 7 females, suffering from AS with severe spinal kyphosis, underwent 1-stage interrupted 2-level transpedicular wedge osteotomy in our hospital by the corresponding author. Improvements in relevant parameters were recorded and clinical results were evaluated.

RESULTS

The average operating time was 282±43 minutes, and the average blood loss was 2202±737 mL. All the global and regional spinal alignments improved to relatively normal status: the global thoracolumbar kyphosis angle improved from 101.5±10.8 to 24.8±5.8 degrees (P<0.001), the thoracolumbar kyphosis improved from 37.9±5.1 to 0.7±12.8 degrees (P<0.001), and the lumbar lordosis improved from 35.0±9.2 to -25.7±10.9 degrees (P<0.001). Meanwhile, the chin-brow vertical angle improved from 79.5±5.1 to 8.5±2.7 degrees (P<0.001), and the sagittal imbalance distance improved from 49.6±6.5 to 11.5±3.5 cm (P<0.001). All the patients could walk with horizontal vision and lie on their backs postoperatively, and scoliosis research society-22 scores improved from 1.6±0.2 preoperatively to 4.3±0.2 at the 2-year follow-up. The mean time of follow-up was 52±28 months. Fusion of the osteotomy was achieved in each patient and no instances of loss of correction or implant failure were noted.

CONCLUSION

For correcting severe kyphosis in patients with AS, the 1-stage interrupted 2-level transpedicular wedge osteotomy is a safe and effective technique that significantly improves appearance and function.

Does the Traversing Length of the Aorta Change After Closing Wedge Osteotomy for Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis?: A Magnetic Resonance Imaging Investigation

STUDY DESIGN

A prospective magnetic resonance imaging (MRI) study.

OBJECTIVE

To investigate the change in aortic traversing length in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) after closing wedge osteotomy (CWO).

SUMMARY OF BACKGROUND DATA

The CWO has been widely adopted for the correction of thoracolumbar kyphosis caused by AS. During this procedure, the aorta may be elongated in the instrumented area, which implies a potential risk of the aortic injury. To date, no reports have been specifically published using MRI to investigate the alteration in aortic traversing length in patients with AS undergoing CWO.

METHODS

From June 2013 to July 2015, 24 patients with AS with thoracolumbar kyphosis with a mean age of 38.1 years were recruited in the present study. All patients underwent single-level CWO. MRI examinations were performed before and 2 weeks after surgery. For each subject, the aortic diameter and length were measured on the MRI. Radiographic measurements included the global kyphosis, thoracic kyphosis, lumbar lordosis, local kyhosis, angle of fusion levels, and anterior height of the osteotomized vertebra. The height of these patients was also recorded.

RESULTS

The aortic traversing length significantly increased by an average of 2.0 cm after surgery. Significant changes in height, global kyphosis, lumbar lordosis, local kyphosis, and angle of fusion levels were observed (P < 0.01), whereas the anterior height of the osteotomized vertebra was comparable before and after surgery (P > 0.05). In addition, the correlation analysis revealed a significant correlation between the aortic traversing length and changes in global kyphosis, lumbar lordosis, local kyphosis, angle of fusion levels, and height (P < 0.01).

CONCLUSION

The stretch of the aorta after CWO for the correction of thoracolumbar kyphosis was quantitatively verified by MRI investigation in the present study. Spine surgeons should be aware of the potential vulnerability of aortic injury in patients with AS undergoing CWO.

LEVEL OF EVIDENCE

4.

Computer Simulation of Two-level Pedicle Subtraction Osteotomy for Severe Thoracolumbar Kyphosis in Ankylosing Spondylitis

BACKGROUND

Advanced ankylosing spondylitis is often associated with thoracolumbar kyphosis, resulting in an abnormal spinopelvic balance and pelvic morphology. Different osteotomy techniques have been used to correct AS deformities, unfortunnaly, not all AS patients can gain spinal sagittal balance and good horizontal vision after osteotomy.

MATERIALS AND METHODS

Fourteen consecutive AS patients with severe thoracolumbar kyphosis who were treated with two-level PSO were studied retrospectively. All were male with a mean age of 34.9 ± 9.6 years. The followup ranged from 1-5 years. Preoperative computer simulations using the Surgimap Spinal software were performed for all patients, and the osteotomy level and angle determined from the computer simulation were used surgically. Spinal sagittal parameters were measured preoperatively, after the computer simulation, and postoperatively and included thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence, pelvic tilt (PT), and sacral slope (SS). The level of correlation between the computer simulation and postoperative parameters was evaluated, and the differences between preoperative and postoperative parameters were compared. The visual analog scale (VAS) for back pain and clinical outcome was also assessed.

RESULTS

Six cases underwent PSO at L1 and L3, five cases at L2 and T12, and three cases at L3 and T12. TK was corrected from 57.8 ± 15.2° preoperatively to 45.3 ± 7.7° postoperatively (P < 0.05), LL from 9.3 ± 17.5° to -52.3 ± 3.9° (P < 0.001), SVA from 154.5 ± 36.7 to 37.8 ± 8.4 mm (P < 0.001), PT from 43.3 ± 6.1° to 18.0 ± 0.9° (P < 0.001), and SS from 0.8 ± 7.0° to 26.5 ± 10.6° (P < 0.001). The LL, VAS, and PT of the simulated two-level PSO were highly consistent with, or almost the same as, the postoperative parameters. The correlations between the computer simulations and postoperative parameters were significant. The VAS decreased significantly from 6.1 ± 1.9 to 2.0 ± 1.1 (P < 0.001). In terms of clinical outcome, 10 cases were graded "excellent" and 4 cases were graded "good."

CONCLUSION

Two-level PSO using a preoperative computer simulation is a feasible, safe, and effective technique for the treatment of severe thoracolumbar kyphosis in AS patients with normal cervical motion.

Y Shape Osteotomy in Ankylosing Spondylitis, a Prospective Case Series with Minimum 2 Year Follow-Up

The aim of the study is to evaluate the efficacy of a spinal osteotomy technique, Y shape osteotomy, for correcting kyphosis in AS patients planned preoperatively with computer software-assistance. 36 consecutive AS patients with thoracolumbar kyphosis were treated with one-stage posterior Y shape osteotomy and preoperative surgical planning was done with the aid of the Surgimap Spine. Radiological parameters of simulation and immediate postoperation were documented. Clinical and radiological results were evaluated in the preoperative, the early postoperative periods and during the last follow-up. The lumbar lordosis was found as 40.7 ± 4.1 degrees in the surgical planning and 49.7 ± 3.9 degrees postoperatively (p<0.01). PI-LL was 3.8± 0.9°in the simulation procedure and 6.6± 1.5°postoperatively (p<0.01). At the final follow-up, Global sagittal balance was restored and Both Oswestry Disability Index and Scoliosis Research Society scores improved largely. In conclusion, Y shape osteotomy is a safe and effective treatment option for AS patients with kyphosis deformity.

The Precise Bending Rod Technique: A Novel Method for Precise Correction of Ankylosing Spondylitis Kyphosis

STUDY DESIGN

To report a new technique.

OBJECTIVE

To introduce a new method of precise correction controlling for ankylosing spondylitis kyphosis.

SUMMARY OF BACKGROUND DATA

The exact angle method is excellent for calculating the pedicle subtraction osteotomy angle but is difficult to perform during surgery. In this study, the precise rod bending technique was proposed as a new method for precise correction controlling for ankylosing spondylitis kyphosis through illustrative cases.

METHODS

A preoperative plan using the exact angle method, with exact osteotomy angle and level determined, was prepared using a whole-spine lateral x-ray film. Then a precise contoured rod imitating the predicted spine correction was obtained using the lateral spine x-ray film that was of the actual size of the trunk. This rod model was disinfected and used for precisely controlling kyphosis correction in ankylosing spondylitis patients with good cervical spine and hip joints.

RESULTS

Four ankylosing spondylitis kyphosis patients were successfully corrected using the precise bending rod technique. Their mean age was 31 years, the mean operative time was 247 minutes (160-320 min), the mean volume of bleeding was 1482 mL (727-2700 mL), and the average follow-up period was 13.8 months (9-17 mo). All patients regained their sagittal balance (all C7-SSVL≤2 cm). The predicted ostetomy degree was accurate to within 2 degrees compared with the achieved degree at the osteotomy site. No complications occurred during or after surgery.

CONCLUSIONS

The precise rod bending technique is a simple, effective method for precise correction of kyphosis caused by ankylosing spondylitis. The surgical result corresponded to the preoperative planning.

How to Calculate the Exact Angle for Two-level Osteotomy in Ankylosing Spondylitis?

STUDY DESIGN

A prospective case series study.

OBJECTIVE

To describe and assess a two-level osteotomy method for the management of severe thoracolumbar kyphosis (TLK) in patients with ankylosing spondylitis (AS).

SUMMARY OF BACKGROUND DATA

To achieve better postoperative outcomes in these patients, a sophisticated preoperative surgical plan is required. Most deformities are managed using a one-level osteotomy and a two-level osteotomy is seldomly reported. Till date, no study has described a two-level osteotomy for these cases.

METHODS

From January 2011 to December 2012, 10 consecutive patients with ankylosing spondylitis who underwent two-level spinal osteotomy were studied. Pre- and postoperative full-length free-standing radiographs, including the whole spine and pelvis, were available for all patients. Pre- and postoperative radiological parameters, including T5-S1 Cobb angles, TLK, lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope, and sagittal vertical axis were measured. Health related quality of life , including Oswestry Disability Index and Scoliosis Research Society-22 surveys were administered before surgery and at 1-year follow up.

RESULTS

The preoperative and postoperative T5-S1 Cobb angles was 51.3° and -7.1°, respectively (P < 0.001). All patients demonstrated changes in postoperative radiographic parameters including decreased pelvic tilt (from 37.1° to 14.3°, P < 0.001), TLK (from 36.9° to 12.6°, P < 0.001), and sagittal vertical axis (from 21.4 cm to 7.1 cm, P < 0.001), increased lumbar lordosis (from -5.1° to -47.1°, P < 0.001), sacral slope (from 13.4° to 37.7°, P < 0.001), but no significant change in pelvic incidence. Health related quality of life scores at 1-year follow up were significantly improved compared to those before surgery.

CONCLUSION

This calculation of two-level osteotomy provides an accurate and reproducible method for ankylosing spondylitis correction. By which, we can obtain satisfactory radiological parameters and clinical outcomes.

LEVEL OF EVIDENCE

4.

Comparison of Sagittal Spinopelvic Alignment in Patients With Ankylosing Spondylitis and Thoracolumbar Fracture

This article is a comparative study. The aim of the study is to investigate the difference of sagittal alignment of the pelvis and spine between patients with thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) and thoracolumbar fracture, and to evaluate the role of sacropelvic component in AS patients' adaption to the changes in sagittal alignment. Advanced stages of AS are often associated with thoracolumbar kyphosis, resulting in an abnormal spinopelvic balance and pelvic morphology, whereas thoracolumbar fractures may lead to major kyphosis with a potential compromise of the spinal canal, which can cause an abnormal spinopelvic balance. Until now, the comparison of that sagittal alignment between AS and thoracolumbar fracture is not found in the literature. This study included 30 cases of AS and 30 cases of thoracolumbar fracture. Sagittal spinal and pelvic parameters were measured from the standing lateral radiograph, and the following 11 radiological parameters were measured, including global kyphosis (GK), thoracic kyphosis (TK), C7 tilt (C7T), sagittal vertical axis (SVA), spino-pelvic angle (SSA), lumbar lordosis (LL), upper arc of lumbar lordosis (ULL), lower arc of lumbar lordosis (LLL), pelvic incidence (PI), sacrum slope (SS), pelvic tilt (PT), and T9 tilt (T9T). Analysis of variance was used in the comparison of each dependent variable between the 2 cohorts. The relationship between sagittal spinal alignment and pelvic morphology of AS patients was determined via Pearson correlation coefficient (r). Compared with the thoracolumbar fracture group, AS patients had significantly lower C7T, SSA, LL, LLL and SS (78.3° ± 9.3° vs 88.0° ± 2.7°, P < 0.001 for C7T; 91.6° ± 22.7° vs 119.1° ± 9.0°, P < 0.001 for SSA; 20.7° ± 21.0° vs 36.3° ± 16.8°, P = 0.001 for LL; 18.1° ± 11.9° vs 29.0° ± 9.7°, P < 0.001 for LLL; and 18.1° ± 11.9° vs 29.0° ± 9.7°, P < 0.001 for SS), whereas in terms of SVA and PT, AS patients had an obviously higher value than those of thoracolumbar fracture patients (94.5 mm ± 58.4  mm vs 8.0 mm ± 23.3  mm, P < 0.001 for SVA; and 26.5° ± 10.3° vs 17.5° ± 6.6°, P < 0.001 for PT). In AS patients, SS were found to be significantly correlated with SVA, SSA, and LL (r = -0.312, P < 0.05 for SVA; r = 0.475, P < 0.05 for SSA; r = 0.809, P < 0.001 for LL). In our study, there were significant differences in sagittal alignment of the pelvis and spine between patients with AS and thoracolumbar fracture, and changes in pelvic morphology compensated more in AS patients for a thoracolumbar kyphosis. These findings may be helpful for better understanding of sagittal alignment in patients with thoracolumbar kyphosis secondary to AS.

Change in Abdominal Morphology After Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: A Computed Tomographic Study

STUDY DESIGN

A computed tomographic study.

OBJECTIVE

To investigate the change in abdominal morphology in surgically treated patients with ankylosing spondylitis (AS) and thoracolumbar kyphosis.

SUMMARY OF BACKGROUND DATA

Severe thoracolumbar kyphosis in patients with AS exerts pressure on the abdominal cavity and subsequently causes intra-abdominal complications. Several spinal osteotomy techniques have been widely used to correct AS-related thoracolumbar kyphosis. To date, the changed abdominal morphology in patients with AS undergoing surgical correction of thoracolumbar kyphosis has not been addressed.

METHODS

A total of 29 patients with AS undergoing lumbar pedicle subtraction osteotomy for correction of thoracolumbar kyphosis were retrospectively reviewed. Computed tomographic scans of the spine were used to measure the longitudinal, transverse, and anterior-posterior diameters of the abdominal cavity. Furthermore, the abdominal cavity was considered as an ellipsoid structure, thereby allowing calculation of its volume. Radiographical evaluations included global kyphosis (GK), thoracic kyphosis, lumbar lordosis (LL), and angle of fusion levels (AFL).

RESULTS

The longitudinal diameter of abdominal cavity significantly increased (P < 0.01), whereas the transverse and anterior-posterior diameters of the abdominal cavity did not change, postoperatively (P > 0.05). Significant changes in GK, LL, and AFL were observed (P < 0.01). The abdominal cavity volume (ACV) increased by an average of 652  mL. The change in ACV was significantly correlated with the changes in GK (r = 0.453, P = 0.014), LL (r = 0.42, P = 0.023), and AFL (r = 0.388, P = 0.037).

CONCLUSION

The increased ACV after correction of thoracolumbar kyphosis was quantitatively confirmed by this study. Thus, the improvement in digestive function after correction of thoracolumbar kyphosis secondary to AS, which has been previously documented, may be because of an increase in ACV. Moreover, spine surgeons should be aware of the potential risk for the development of abdominal complications caused by the lengthening of longitudinal diameter of the abdominal cavity.

LEVEL OF EVIDENCE

3.

Transpedicular wedge osteotomy for treatment of kyphosis after L1 fracture using intraoperative, full rotation, three-dimensional image (O-arm)-based navigation: a case report

There has been a large series in the literature reporting on results of osteotomy for the correction of kyphotic deformity secondary to post-traumatic thoracolumbar fracture. However, there are few reports on using intraoperative, full rotation, three dimensional image (O-arm)-based navigation, transpedicular wedge osteotomy for the correction of kyphotic deformity in old thoracolumbar fracture. A 45-year-old woman with L1 old fracture, presented to us with a Cobb angle of 45 degrees. The preoperative standard anteroposterior, lateral views and computed tomography (CT) reconstructions revealed kyphotic deformity. After attaching the reference arc of the 3D-imaging system, the thoracolumbar spine was screened using an O-arm without anatomical registration. The location, angle and depth of osteotomy, as well as screw fixation were performed using a guide tube while referring to the reconstructed 3D-anatomical views. The surgery was successful without nervous and vascular injuries. Using intraoperative, full rotation, three dimensional image (O-arm)-based navigation, the transpedicular wedge osteotomy is a safe and effective treatment for kyphosis after the thoracolumbar fracture, which can insert the pedicular screw accurately, trace the real-time wedge osteotomy and reduce the loss of correction of kyphotic deformity.

Comparison of two surgeries in treatment of severe kyphotic deformity caused by ankylosing spondylitis: Transpedicular bivertebrae wedge osteotomy versus one-stage interrupted two-level transpedicular wedge osteotomy

OBJECTIVE

To explore a simple and effective surgery for correcting severe kyphotic deformity caused by ankylosing spondylitis (AS).

MATERIALS AND METHODS

From January 2003 to December 2009, we respectively reviewed 32 patients with severe spinal kyphosis caused by AS with at least 2-year follow-up. Patients were divided into two groups, according to surgical methods: transpedicular bivertebrae wedge osteotomy (Group A) or one-stage interrupted two-level transpedicular wedge osteotomy (Group B). We recorded operating time and blood loss. Variation between pre- and post-operative sagittal imbalance, global spinal alignments (Cobb angle of T1 and L5, TLKA), lumbar lordosis, chin-brow vertical angle, thoracolumbar kyphosis angle in both groups were analyzed.

RESULTS

The average operating time was 236 ± 39 min and the average blood loss was 2200 ± 712 ml in Group A, and 252 ± 43 min, 2202 ± 737 ml respectively in Group B. There were no significant differences in operating time and blood loss. Variation between pre- and post-operative sagittal imbalance, global spinal alignments, lumbar lordosis and chin-brow vertical angle (CBVA) were comparable between the two groups. The variation of thoracolumbar kyphosis angle was significantly greater in Group B compared with Group A. SRS-22 scores were similar in the two groups at the 2-year follow-up and significantly improved compared with preoperative.

CONCLUSIONS

For correcting severe kyphosis in patients with AS, the one-stage interrupted two-level transpedicular wedge osteotomy is a safe and effective technique which can significantly improve the thoracolumbar kyphosis angle.

The radiologic, clinical results and digestive function improvement in patients with ankylosing spondylitis kyphosis after pedicle subtraction osteotomy

BACKGROUND CONTEXT

Although there have been several reports describing the radiologic and clinical outcomes of pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) with spinal kyphotic deformity, little is known about the digestive function improvement in AS kyphosis after PSO.

PURPOSE

The aim was to assess radiologic and clinical results and digestive function improvement in patients with AS kyphosis after PSO.

STUDY DESIGN/SETTING

This was a retrospective clinical study.

PATIENT SAMPLE

From January 2009 to July 2013, 53 patients in our department with AS kyphotic deformity who underwent PSO were reviewed.

OUTCOME MEASURES

The globe kyphosis (GK) was measured. A health-related quality of life included Oswestry Disability Index (ODI) and Scoliosis Research Society outcomes instrument-22 (SRS-22). The acreage of the abdominal median sagittal plane (AMSPA) and the minimum distance (MD) between the xiphoid process and the spine or between the abdominal wall and the spine when the abdominal wall was folded into abdomen were measured on the three-dimensional computed tomography scans. The positional changes of abdominal viscera, such as the liver, spleen, and kidney, were also measured. Digestive function assessment included weight and the food intake (FI), and the change of the defecate frequency was recorded.

METHODS

A paired sample t test was performed to determine the differences between the preoperative and postoperative MD, AMSPA, and weight, respectively. A paired sample t test was also performed to determine the differences between preoperative and postoperative Cobb angles and Oswestry Disability Index (ODI), SRS-22 for all the patients, respectively. A paired sample t test was also performed to determine the positional changes of abdominal viscera. Description date was presented as mean±standard deviation. Additionally, an independent sample t test was performed to determine the differences between the patients (Group 1) who had defecate frequency change and the remaining patients (Group 2) for preoperative GK, age, and disease duration, respectively. An independent sample t test was also performed to determine the differences between the patients (Group A) who had obviously increased FI and the remaining patients (Group B) for preoperative GK, age, and disease duration, respectively.

RESULTS

All the patients had good radiologic and clinical results, postoperatively. The postoperative positions of the abdominal viscera were changed significantly. The weight, the mass of FI, and the defecate frequency were also changed significantly, postoperatively. The preoperative GK, age, and disease duration were not significantly statistical different between the patients who had defecate frequency change and the remaining patients, respectively. There were also not significantly statistical differences between the patients who had obviously increased FI and the remaining patients in preoperative age and disease duration. There was a significantly statistical difference between the patients who had obviously increased FI and the remaining patients for preoperative GK.

CONCLUSIONS

The single-level or two-level PSO is an effective and safe technique to correct AS kyphosis. And the conditions of extrusion of viscera by trunk flexion decreased volume of the abdominal cavity, and abnormal visceral positions were improved by the osteotomy, followed with digestive function improvement.

Comparison of Smith-Petersen osteotomy and pedicle subtraction osteotomy for the correction of thoracolumbar kyphotic deformity in ankylosing spondylitis: a systematic review and meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

To compare the efficacy and safety outcomes of Smith-Petersen osteotomy (SPO) and pedicle subtraction osteotomy (PSO) for patients with ankylosing spondylitis (AS) with thoracolumbar kyphotic deformity.

SUMMARY OF BACKGROUND DATA

Both SPO and PSO are used to correct thoracolumbar kyphotic deformity due to AS. Evidence is insufficient to determine which has better efficacy and safety outcomes.

METHODS

A systematic literature search was performed. Studies concentrating on treating thoracolumbar kyphotic deformity due to AS with SPO and/or PSO were included. Efficacy was determined with radiographical outcomes, including sagittal vertical axis and lumbar lordosis. Safety was determined with complication rates. The data were analyzed with Review Manager and R software.

RESULTS

Twenty-three studies were included. Among them, 5 were comparative studies and were used for a meta-analysis. All 23 studies were pooled to evaluate the radiographical correction and incidence of complications. The meta-analysis of the 5 comparative studies showed no significant difference between groups in either correction of sagittal vertical axis and lumbar lordosis or incidence of complications. The pooled data also showed similar radiological correction and complication rates between SPO and PSO. SPO was found to have potential risk of aortic rupture and slightly higher risk of permanent neurological deficit without statistical significance, whereas PSO was shown longer operative time and more blood loss.

CONCLUSION

This systematic review and meta-analysis demonstrates that both SPO and PSO are effective in correcting thoracolumbar kyphotic deformity in AS and have similar risk of most complications. Aortic rupture and related death during correction is reported in SPO and should be taken into consideration for decision making.

LEVEL OF EVIDENCE

4.

Radiologic and clinical outcomes comparison between single- and two-level pedicle subtraction osteotomies in correcting ankylosing spondylitis kyphosis

BACKGROUND CONTEXT

Single pedicle subtraction osteotomy (PSO) has been used to correct ankylosing spondylitis (AS) kyphosis successfully, but this approach seems insufficient to correct severe kyphosis. Two-level PSO has been attempted to correct advanced kyphosis in recent years. However, studies have not yet compared outcomes between single and double PSOs, and the indications to perform two-level PSO are unclear.

PURPOSE

This study aimed to compare the radiologic and clinical outcomes between single- and two-level PSOs in correcting AS kyphosis.

STUDY DESIGN

This work is a retrospective cohort study.

PATIENT SAMPLE

Sixty patients were included. Thirty-seven underwent single-level PSO, and 23 underwent one stage two-level PSO.

OUTCOME MEASURES

The radiologic analysis included thoracic kyphosis, thoracolumbar junction, lumbar lordosis, pelvic index, chin-brow vertical angle (CBVA), sagittal vertical axis (SVA), and pelvic tilt (PT). Clinical assessment was performed with a Scoliosis Research Society-22 (SRS-22) outcomes instrument. The operative time, blood loss, and complications were also documented.

METHODS

All of the aforementioned measurements were recorded before surgery, after surgery, and at the last follow-up. The outcomes were compared between the two groups.

RESULTS

The operating time was 232±52 minutes for single- and 282±43 minutes for two-level PSOs. The blood loss was 1,240±542 mL (Level 1) and 2,202±737 mL (Level 2). The total spine correction was 43.2°±15.1° (Level 1) and 60.6°±19.1° (Level 2) (p<.001), the SVA correction was 13.2±10.6 cm (Level 1) and 23.6±10.2 cm (Level 2) (p<.001), and the PT correction was 10.1°±11.6° (Level 1) and 15.2°±10.8° (Level 2) (p<.001). The CBVA correction was 50.6°±17.8° (Level 1) and 51.4°±18.6° in (Level 2) (p>.05). All patients could walk with horizontal vision and lie on their backs postoperatively. The SRS-22 improved from 1.7±0.4 to 4.2±0.8 in the two-level group and 1.8±0.8 to 4.3±0.7 in the single-level group. The fusion of the osteotomy was achieved in each patient. The complications were similar in both groups.

CONCLUSIONS

Pedicle subtraction osteotomy is an effective method to correct kyphosis with AS. Most patients can be successfully treated by single PSO. In severe patients, two-level PSO may be preferable because its correction ability is greater and spine curvature is better than that of single-level PSO. However, two-level PSO requires an increased operating time and results in increased blood loss. Nevertheless, the complications were similar between the two groups.