Pedicle subtraction osteotomy through pseudarthrosis to correct thoracolumbar kyphotic deformity in advanced ankylosing spondylitis

Clinical Observation of Posterior Approach for Surgical Treatment of Thoracolumbar Pseudarthrosis in Ankylosing Spinal Disorders

OBJECTIVE

The objective of this study was to evaluate the surgical effectiveness of posterior procedure with long segment stabilization for treating thoracolumbar pseudarthrosis associated with ankylosing spinal disorders (ASDs) without anterior fusion or osteotomy.

METHODS

Twelve patients with thoracolumbar pseudarthrosis in ASD were enrolled. All patients underwent posterior long-segment stabilization procedures. In some patients, the percutaneous technique or the aid of a robot or O-arm navigation was utilized for pedicle screw implantation. The clinical results were evaluated by means of the visual analog scale and Oswestry Disability Index. Radiological outcomes were evaluated for bone fusion, anterior column defect, local kyphotic correction, and position of the pedicle screws.

RESULTS

All patients experienced effective bone fusion at the sites of pseudarthrosis. The mean operative time was 161.7 ± 57.1 minutes, and the average amount of blood loss was 305.8 ± 293.2 mL. For 6 patients who underwent surgery with the assistance of a robot or O-arm navigation, there was no statistically significant difference observed in terms of operative time and mean blood loss compared to those who used the freehand technique (P > 0.05). The visual analog scale score, Oswestry Disability Index value, and mean local kyphotic angle showed significant improvements at the final follow-up (P < 0.05). The accuracy of pedicle screw placement was 96%.

CONCLUSIONS

Posterior surgery with long-segment fixation, without anterior fusion or osteotomy, can achieve satisfactory outcomes in ASD patients with thoracolumbar pseudarthrosis. The application of percutaneous techniques, as well as the assistance of robots or navigation technique may be a good choice for the treatment of pseudarthrosis in ASD patients.

Long-term outcome evaluation in ankylosing spondylitis with high-angle thoracolumbar kyphotic deformity corrected by one-stage single-level pedicle subtraction osteotomy augmented with Ponte osteotomy: A case series

INTRODUCTION AND IMPORTANCE

A high-angle thoracolumbar kyphotic deformity (TLKD) may complicate surgical rectification of AS patients since one-stage two-level pedicle subtraction osteotomy (PSO), which provides high-angular correction, leads to excessive blood loss, neurological deficits and fixation failures. This case series presents the long-term results of one-stage single level PSO with Ponte osteotomy (PO) in the treatment of AS patients with high-angle TLKD.

CASE PRESENTATION

This case series presents two AS patients with high kyphotic angles (KAs) of 86.1o. We collected data retrospectively from our institution's database between 2019 and 2023. A sagittal axis imbalance was the only complaint initially, no neurological deficits or other problems. A PSO augmented by PO was performed with a decompression laminectomy. Intraoperative monitoring (IOM) during reduction was used to observe neurological deficits. Blood loss at the highest rate was 1000 cc. It corrected 57.8o of KA postoperatively without neurological deficits. We found consistent results over 36 months.

CLINICAL DISCUSSION

A thorough analytical approach may help diagnose AS. One-stage single-level PSO may correct high-angle TLKD in AS patients effectively. To achieve greater angular correction, PO, a less risky osteotomy, must be added. Decompression laminectomy is vital before osteotomy and IOM is crucial during reduction to prevent nerve injury. Even with two osteotomies, there was less blood loss than previously reported. These impressive long-term results call for further research.

CONCLUSION

Combined PSO and PO with IOM efficiently magnifies the angular correction without postoperative neurological deficits or excessive blood loss in AS patients with high-angle TLKD.

Is the pelvic incidence a determinant factor for kyphosis curve patterns of ankylosing spondylitis patients?

To investigate the influence of pelvic incidence (PI) on the kyphosis curve patterns and clinical outcomes in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis and to construct a classification of AS according to the PI value for surgical decision-making. 107 AS patients underwent single-level lumbar pedicle subtraction osteotomy (PSO) and finished a minimal of 2-year follow-up. All patients were divided into three groups: low PI (PI ≤ 40°), moderate PI (40° < PI ≤ 60°), and high PI (PI > 60°). Standing lateral radiographs were taken to evaluate the location of kyphotic apex, thoracic kyphosis (TK), lumbar lordosis (LL), C7 sagittal vertical axis (SVA), spino-sacral angle (SSA), global kyphosis (GK), PI, sacral slope (SS), and pelvic tilt (PT). Visual Analogue Scale (VAS) score, Oswestry Disability Index (ODI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were used to evaluate quality of life. Before surgery, a significant difference was shown in the average LL and the mean GK in high PI group was the largest among the three groups. Correction of SVA, GK and LL in high PI group was the smallest among the three group. No significant difference in clinical outcomes was found among the three groups before surgery and at the final follow-up. Regarding the preoperative sagittal profile, the kyphosis curve pattern of moderate PI group is similar to that of low PI group. For AS patients in these two groups, harmonious sagittal alignment can be restored by a single-level PSO. However, the sagittal imbalance is insufficiently realigned by a single-level PSO in a patient with high PI.

Mini-open Pedicle Subtraction Osteotomy versus Standard Posterior Approach for Ankylosing Spondylitis-related Spinal Kyphosis: A Comparative Study

OBJECTIVE

Surgical strategy for spinal kyphosis in patients with ankylosing spondylitis (AS) has been challenging. Pedicle subtraction osteotomy (PSO) through a minimally invasive (MI) approach has been developed with promising clinical outcomes. We aimed to compare the effectiveness and safety of PSO via an MI approach and a standard posterior approach (SPA) for treating AS-related spinal kyphosis.

METHODS

A total of 41 patients with AS-related spinal kyphosis who underwent PSO through an MI approach (MI surgery [MIS] group: n = 25) or SPA (SPA group: n = 16) between January 2015 and July 2020 were retrospectively included. Spinopelvic parameters were evaluated before the surgery, immediately after the surgery, and at the 2-year follow-up. Clinical data including operative time, estimated blood loss, blood transfusion, level of fusion, incision length, bed rest period, length of hospitalization, and surgical complications were compared between the two groups. The Scoliosis Research Society outcomes instrument-22 (SRS-22) was administered to assess patients' quality of life at the latest follow-up. Comparisons between the two groups were performed using independent sample t-test or Chi-square test.

RESULTS

Characteristics and baseline kyphosis of the two groups were matched. At the 2-year follow-up, in the MIS group, the average correction values of the sagittal vertical axis and global kyphosis (GK) were 9.5 cm and 44.3°, respectively. Compared with the SPA group, the MIS group had similar correction values and correction losses after surgery. No obvious differences were observed in any radiographic parameters, except for GK, immediately after surgery and at the 2-year follow-up between the two groups (p > 0.05). The MIS group had a significantly shorter operative time, lesser blood loss, lesser transfusion volume, shorter fusion level, and lesser time to mobilization than did the SPA group. Higher average functional activity scores of SRS-22 were obtained in the MIS group than in the SPA group.

CONCLUSION

Mini-open PSO may be an effective alternative to the SPA for treating AS-related spinal kyphosis, with comparable correction effect, lesser surgical trauma and faster recovery. This comparative study may provide valuable guidance for surgical decision-making and patient counseling.

Video-assisted thoracoscopic surgery for Andersson lesion in ankylosing spondylitis: A case report and literature review

RATIONALE

Andersson lesion (AL), a phenomenon initially described by Andersson nearly 80 years ago, has been the subject of extensive research and various treatment modalities. The ongoing debate surrounding the need for anterior surgery in AL cases has spurred numerous proposed approaches. Despite the demonstrated efficacy of anterior surgery in achieving fusion and stabilization, its implementation is associated with prolonged operation time and heightened intraoperative bleeding.

PATIENT CONCERNS

A 32-year-old male patient presented at our hospital in February 2019 with a 2-month history of bilateral lower extremity weakness and sensory disturbances. These symptoms were exacerbated by a recent fall.

DIAGNOSIS

AL conbined with ankylosing spondylitis.

INTERVENTIONS

A 1-stage posterior fixation and decompression procedure was performed to ensure spinal stability, minimize deformities, and reduce surgical trauma. To achieve these goals, a 2-stage approach was employed, which included video-assisted thoracoscope-guided vertebrectomy, spinal canal decompression, and bone graft fusion.

OUTCOMES

No recurrences of significant pain, limb numbness, or other symptoms were reported, ultimately leading to an improved quality of life for the patient.

LESSONS

We utilized video-assisted thoracoscopic surgery technology for anterior bone graft fusion in a patient with AL to minimize the trauma of secondary surgery. However, the 3-year follow-up showed insufficient bony fusion at the fracture site. Nevertheless, the patient maintained spinal stability with posterior internal fixation and no significant kyphosis or symptoms. Thus, standalone posterior fixation may suffice for favorable clinical outcomes in patients with AL.

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.

Remodeling morphology of the subluxated osteotomy vertebra in closing-opening wedge osteotomy in ankylosing spondylitis: would the anterior bony beak blunt?

INTRODUCTION

To investigate the remodeling morphology of subluxated osteotomy vertebra in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis after single-level closing-opening wedge osteotomy (COWO).

MATERIALS AND METHODS

Standing lateral radiographs were taken to evaluate sagittal parameters including lumbar lordosis (LL), C7 sagittal vertical axis (SVA), global kyphosis (GK), sacral slope (SS), and pelvic tilt (PT). Radiographic parameters of the osteotomy vertebra included osteotomized vertebra angle (OVA), sagittal translation (ST), anterior height (AH), posterior height (PH), and middle height (MH) of the osteotomy vertebrae. Furthermore, lateral projection area of the vertebral body was also measured to evaluate the remodeling of the osteotomy vertebrae.

RESULTS

Sixty AS patients who underwent single-level lumbar COWO with a minimal 2-year follow-up were included. The cohort consisted of 54 males and 6 females with an average age of 36.6 years. All patients were divided into two groups according to the development of vertebral subluxation (VS): 15 in VS group (ST ≥ 5 mm), 45 in non-VS group (ST < 5 mm). There was significant difference in the correction of GK, SVA, and the loss of correction of SVA between AS patients with and without VS. Significant difference in vertebra-related parameters regarding AH and OVA was found between VS group and non-VS group (P < 0.05).

CONCLUSIONS

After COWO, new bone formation narrowing the gap and adaptive resorption of the anterior bony beak at the osteotomy level during follow-up was surprisingly favorable. However, the ability of spinal canal remodeling is limited in patients complicated with VS.

Surgical Treatment of Andersson Lesion of the Lumbar Spine with Minimal Invasion: A Case Report

We present a 37-year-old female patient with AL of lumbar spine (L3-4) treated by OLIF combined with pedicle screw fixation (via Wiltse paraspinal approach) with relatively minimal invasion.

Does the Level of Pedicle Subtraction Osteotomy Affect the Surgical Outcomes in Ankylosing Spondylitis-Related Thoracolumbar Kyphosis With the Same Curve Pattern?

STUDY DESIGN

A retrospective study.

OBJECTIVE

To investigate the effect of pedicle subtraction osteotomy (PSO) level on the surgical outcomes in ankylosing spondylitis-related thoracolumbar kyphosis with the same curve pattern.

METHODS

ankylosing spondylitis (AS) patients with thoracolumbar kyphosis, who underwent 1-level lumbar PSO between March 2006 and June 2017, were retrospectively reviewed. Criteria for curve-matched thoracolumbar kyphosis were: (1) have same level of preoperative apex (pre-apex); (2) have similar global kyphosis (GK, the angle between the superior/inferior endplate of the maximally tilted upper and lower end vertebra) (the difference of GK less than 15˚). The radiographic parameters measured were sagittal vertical axis (SVA, the horizontal distance between the C7 plumb line and the posterosuperior corner of the S1), GK, thoracic kyphosis (TK, the angle between the T5 superior endplate and the T12 inferior endplate), lumbar lordosis (LL, the angle between the L1 and S1 superior endplate), sacral slope (SS, the angle between the sacral endplate and the horizontal line), pelvic tilt (PT, the angle between the vertical and the line joining the midpoint of the sacral plate and hip axis), and pelvic incidence (PI, the angle between the line vertical to the superior margin of S1 and the line connecting the sacral plate midpoint with the hip joint axis). All of these parameters and health-related quality of life (HRQoL, evaluated by preoperative and the last follow-up questionnaires including ODI and VAS) scores were collected before surgery and at the last follow-up. According to their osteotomy level, patients were devided into 2 sub-groups (L1 group and L2 group), and differences of these mentioned parameters between 2 groups were compared.

RESULTS

26 curve-matched patients were recruited with a mean follow-up of 37.2 months. All patients improved significantly after surgery in HRQoL scores (VAS 1.6 vs 5.4, P < 0.001; ODI 11.9 vs 26.4, P < 0.001). Except for TK and PI, those radiographic parameters were also observed to be significantly changed after surgery. Compared to L2 group, PSO at L1 may have larger correction of TK (ΔTK -6.8 vs -0.3°, P = 0.164), PI (ΔPI -7.4 vs -0.7°, P = 0.364) and smaller correction of SVA (ΔSVA -105.3 vs -128.5 mm, P = 0.096), LL (ΔLL -31.1 vs -43.0°, P = 0.307) and SS (ΔSS 6.9 vs 12.2°, P = 0.279) but had no statistical significance.

CONCLUSION

The results of this investigation showed that in AS-related thoracolumbar kyphosis patients with the same curve pattern, the different levels of osteotomy had little effect on the improvement of surgical outcomes. However, osteotomy at L2 is more likely to obtain a larger correction of SVA compared to osteotomy at L1.

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.

Management of Andersson lesions of spine: A systematic review of the existing literature

INTRODUCTION

Andersson lesions also termed as aseptic spondylodiscitis, spinal pseudoarthrosis are known to occur in patients with ankylosing spondylitis. Trauma as well as inflammation has been cited as factors responsible for the causation of these lesions. A variety of surgical approaches have been described in the literature such as anterior, posterior, combined anterior and posterior, with or without reconstruction of the anterior column defect. Controversy still exists regarding the optimal management these lesions.

OBJECTIVE

To address the optimal method of management, levels of instrumentation, requirement of fusion and anterior instrumentation and general epidemiological profile of the patients with Andersson lesions.

MATERIALS AND METHODS

An electronic search for studies on the surgical management of Andersson lesions of spine was performed. Quality assessment of the included articles was done by two independent authors according to the criteria used by researchers previously in systematic reviews.

RESULTS

Males were found to have an increased incidence with the thoracolumbar junction being the most common level. Posterior approach was the most favoured with reconstruction of the gap in the anterior column. Posterior osteotomy with correction of deformity was done commonly for an optimal healing environment. Instrumenting 2-3 levels above and below the lesion is favoured by most.

CONCLUSION

Conservative management for Andersson lesions can be employed in the setting of acute trauma and stable fractures involving a single column. Surgical management of these lesions with a posterior long segment fixation and anterior column reconstruction is the favoured treatment in majority of the cases.

Low expression of TCP1 (T-Complex 1) and PSMC1 (Proteasome 26S subunit, ATPase 1) in heterotopic ossification during ankylosing spondylitis

Heterotopic ossification (HO) is frequently seen in patients with spinal injuries. Therefore, this study aimed to characterize the association of HO with ankylosing spondylitis (AS) through gene expression profiling. The human transcriptomic datasets (GSE73754 and GSE94683) were obtained from the Gene Expression Omnibus database for analysis. Overlapping differentially expressed genes (DEGs) were identified between AS and HO disease states. Subsequently, weighted gene co-expression network analysis (WGCNA) was performed for constructing and identifying hub genes for each condition. Finally, a consensus of the overlapping DEGs and the hub genes in AS and HO was taken for determining the key genes involved in AS-induced HO. Quantitative real-time polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels in mesenchymal stem cells of AS patients and controls. Additionally, immunohistochemistry was performed on interspinous ligament samples for experimental validation of genes. DEG analysis identified 355 overlapping genes between HO and AS. WGCNA indicated that the salmon module of the 22 modules constructed, was most significantly correlated with AS-induced HO. Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of the salmon module indicated the presence of genes enriched in proteasome regulatory particle and proteasome pathways. mRNA expression analysis identified TCP1 and PSMC1 as the key genes in AS-induced HO. Further validation of these genes could help elucidate their role in the complex association of AS and HO.

Occult Andersson lesions in patients with ankylosing spondylitis: undetectable destructive lesions on plain radiographs

Background:

Andersson lesions (ALs) are not uncommon in ankylosing spondylitis (AS). Plain radiography (PR) is widely used for the diagnosis of ALs. However, in our practice, there were some ALs in AS patients that could not be detected on plain radiographs. This study aimed to propose the concept of occult ALs and evaluate the prevalence and radiographic characteristics of the occult ALs in AS patients.

Methods:

A total of 496 consecutive AS patients were admitted in the Affiliated Drum Tower Hospital, Medical School of Nanjing University between April 2003 and November 2019 and they were retrospectively reviewed. The AS patients with ALs who met the following criteria were included for the investigation of occult ALs: (1) with pre-operative plain radiographs of the whole-spine and (2) availability of pre-operative computed tomography (CT) and/or magnetic resonance imaging (MRI) of the whole-spine. The occult ALs were defined as the ALs which were undetectable on plain radiographs but could be detected by CT and/or MRI. The extensive ALs involved the whole discovertebral junction or manifested as destructive lesions throughout the vertebral body. Independent-samples t test was used to compare the age between the patients with only occult ALs and those with only detectable ALs. Chi-square or Fisher exact test was applied to compare the types, distribution, and radiographic characteristics between detectable and occult ALs as appropriate.

Results:

Ninety-two AS patients with a mean age of 44.4 ± 10.1 years were included for the investigation of occult ALs. Twenty-three patients had occult ALs and the incidence was 25% (23/92). Fifteen extensive ALs were occult, and the proportion of extensive ALs was significantly higher in detectable ALs (97% vs. 44%, χ² = 43.66, P < 0.001). As assessed by PR, the proportions of osteolytic destruction with reactive sclerosis (0 vs. 100%, χ² = 111.00, P < 0.001), angular kyphosis of the affected discovertebral units or vertebral body (0 vs. 22%, χ² = 8.86, P = 0.003), formation of an osseous bridge at the intervertebral space adjacent to ALs caused by the ossification of the anterior longitudinal ligament (38% vs. 86%, χ² = 25.91, P < 0.001), and an abnormal height of the affected intervertebral space were all significantly lower in occult ALs (9% vs. 84%, χ² = 60.41, P < 0.001).

Conclusions:

Occult ALs presented with more subtle radiographic changes. Occult ALs should not be neglected, especially in the case of extensive occult ALs, because the stability of the spine might be severely impaired by these lesions.

A Novel Mathematical Model to Calculate the Osteotomy in Ankylosing Spondylitis

MINI

The authors developed a mathematical model to the sagittal vertical axis (SVA) change in ankylosing spondylitis whom PSO is planned. The mathematical model was developed using trigonometric equations. No significant difference exists between postop SVA change amount and SVA calculated. The mathematical model is reliable in restoring the global sagittal balance.

Variation patterns of cervical alignment in ankylosing spondylitis-related thoracolumbar kyphosis following pedicle subtraction osteotomy in the sitting position: an EOS-based investigation

OBJECTIVE

Both unchanged upper cervical lordosis combined with decreased lower cervical lordosis and decreased upper cervical lordosis combined with decreased lower cervical lordosis have been reported to occur after correction surgery for adult spinal deformity. However, variations in cervical alignment after correction surgery in patients with ankylosing spondylitis (AS) have not been investigated. The current study aimed to investigate the variations in cervical alignment following the correction surgery in AS patients with thoracolumbar kyphosis.

METHODS

Patients with AS who underwent pedicle subtraction osteotomy (PSO) for thoracolumbar kyphosis from June 2016 to June 2019 with a minimum of 1-year follow-up were reviewed. Patients were grouped according to the presence (ossified group) and absence (non-ossified group) of total ossification of the anterior longitudinal ligament (ALL) in the lower cervical spine. Radiographic parameters, including thoracolumbar, craniocervical, and global radiographic parameters, were measured on lateral sitting EOS images.

RESULTS

Thirty-two patients (27 males and 5 females) with a mean follow-up of 1.5 years were identified. There were 21 patients in the non-ossified group and 11 patients in the ossified group. After PSO, both groups showed a decrease in the occiput-C7 angle (p < 0.001 for both). In the non-ossified group, the C2-7 angle decreased significantly (p < 0.001), while the occiput-C2 angle remained unchanged (p = 0.570). In the ossified group, the occiput-C2 angle decreased significantly (p < 0.001), while C2-7 angle remained unchanged (p = 0.311). In addition, the change in occiput-C2 was correlated with the osteotomy angle in the ossified group (R = 0.776, p = 0.005).

CONCLUSIONS

The variation patterns of cervical alignment following correction surgery for AS-related thoracolumbar kyphosis were different based on patients with or without total ossification of ALL in the lower cervical spine. When planning PSO for patients in the ossified group, restoration of the physiological upper cervical lordosis angle could be achieved by adjusting the osteotomy angle.

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.

The contribution of pre-existing spinal pseudarthrosis to the surgical correction for thoracolumbar kyphosis secondary to ankylosing spondylitis

The correction of global kyphosis (GK) for ankylosing spondylitis (AS) patients with pre-existing pseudarthrosis were frequently over 45°. Mismatch between kyphosis correction of GK and pedicle subtraction osteotomy (PSO) may be ascribed to contribution of pseudarthrosis. The aim of the present study was to evaluate surgical outcomes of PSO away from the level of pseudarthrosis and to elucidate the contribution of pre-existing spinal pseudarthrosis in surgical correction of thoracolumbar kyphosis caused by AS. Eighteen AS patients with pre-existing pseudarthrosis were included. PSO outside the level of pseudarthrosis were performed for all the patients. The average follow-up period were 29 months. Radiographs were analyzed for correction and complications. Significant improvement in all sagittal parameters were found postoperatively without obvious correction loss at the final follow-up. Local kyphosis (LK) improved from 23.88° preoperatively to 12.67° postoperatively with a mean correction of 11.47°. Average correction of per PSO segment, GK and sum of disc wedging within fused region (SDW) were 33.53°, 49.27° and 4.00°, respectively. PSO away from the level of pseudarthrosis, but with posterior instrumentation crossing it was a feasible method and was able to maintain sustained surgical outcomes. Regarding GK correction, PSO accounted for 68.1% while pre-existing pseudarthrosis provided 23.3%, which resulted from anterior column opening postoperatively. Thus, extra kyphosis correction attributed to pre-existing pseudarthrosis should be considered for surgical-decision making to prevent overcorrection.

Improvement of Sleep Quality in Patients With Ankylosing Spondylitis Kyphosis After Corrective Surgery

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study is to investigate the changes in sleep quality in patients surgically treated for kyphosis due to ankylosing spondylitis (AS) and the correlation between these changes and spinal sagittal realignment.

SUMMARY OF BACKGROUND DATA

Sleep problems are prevalent in AS patients. However, little attention has been paid to the sleep quality in patients with AS kyphosis and the effect of surgical intervention on sleep quality.

METHODS

We have retrospectively reviewed 62 patients with AS-induced thoracolumbar kyphosis who underwent surgically treatment from October 2012 to November 2016. Sleep quality was evaluated by the Pittsburgh Sleep Quality Index (PSQI) questionnaire. Preoperative and postoperative radiological characteristics and supine function were documented. We compared the above-mentioned parameters pre- and 24 months postoperatively and analyzed the correlation of the changes in the PSQI with the changes in radiological characteristics.

RESULTS

Fifity-one patients (82%) classified as poor sleepers preoperatively. In addition to use of sleeping medication, each domain of the PSQI and the total PSQI were increased postoperatively. Improved sleep quality was correlated with changes in spinal sagittal characteristics, among which the lumbar lordosis (LL) and the chin-brow vertical angle (CBVA) were the independent correlation factors. The number of patients with supine dysfunction decreased from 89% to 15% after surgery. Significant differences were identified in the PSQI scores between the patients with and without supine dysfunction either pre- or postoperatively.

CONCLUSION

Surgical correction of spinal deformity may improve sleep quality and supine function in patients with AS. Spinal sagittal realignment may be correlated with the improvement of sleep quality.

LEVEL OF EVIDENCE

4.

A modified posterior wedge osteotomy with interbody fusion for the treatment of thoracolumbar kyphosis with Andersson lesions in ankylosing spondylitis: a 5-year follow-up study

Background

Andersson lesions (ALs), also known as spondylodiscities, destructive vertebral lesions and spinal pseudarthrosis, usually occur in patients with ankylosing spondylitis (AS). Inflammatory and traumatic causes have been proposed to define this lesion. Different surgical approaches including anterior, posterior, and combined anterior and posterior procedure have been used to address the complications, consisting of mechanical pain, kyphotic deformity, and neurologic deficits. However, the preferred surgical procedure remains controversial. The aim of this study was to illustrate the safety, efficacy, and feasibility of a modified posterior wedge osteotomy for the ALs with kyphotic deformity in AS.

Methods

From June 2008 to January 2013, 23 patients (18 males, 5 females) at an average age of 44.8 years (range 25–69 years) were surgically treated for thoracolumbar kyphosis with ALs in AS via a modified posterior wedge osteotomy in our department. All sagittal balance parameters were assessed by standing lateral radiography of the whole spine before surgery and during the follow-up period. Assessment of radiologic fusion at follow-up was based on the Bridwell interbody fusion grading system. Ankylosing spondylitis quality of life (ASQoL) and visual analog scale (VAS) scores were performed to evaluate improvements in daily life function and back pain pre-operatively and post-operatively. Paired t tests were used to compare clinical data change in parametric values before and after surgery and the Mann-Whitney U test was employed for non-parametric comparisons. The radiographic data change was evaluated by repeated measure analysis of variance.

Results

The mean operative duration was 205.4 min (range 115–375 min), with an average blood loss of 488.5 mL (range 215–880 mL). Radiographical and clinical outcomes were assessed after a mean of 61.4 months of follow-up. The VAS back pain and ASQoL scores improved significantly in all patients (7.52 ± 1.31 vs. 1.70 ± 0.70, t = 18.30, P < 0.001; 13.87 ± 1.89 vs. 7.22 ± 1.24, t = 18.53, P < 0.001, respectively). The thoracolumbar kyphosis (TLK) changed from 40.03 ± 17.61° pre-operatively to 13.86 ± 6.65° post-operatively, and 28.45 ± 6.63° at final follow-up (F = 57.54, P < 0.001), the thoracic kyphosis (TK) changed from 52.30 ± 17.62° pre-operatively to 27.76 ± 6.50° post-operatively, and 28.45 ± 6.63° at final follow-up (F = 57.29, P < 0.001), and lumbar lordosis (LL) changed from −29.56 ± 9.73° pre-operatively to −20.58 ± 9.71° post-operatively, and −20.73 ± 10.27° at final follow-up (F = 42.50, P < 0.001). Mean sagittal vertical axis (SVA) was improved from 11.82 ± 4.55 cm pre-operatively to 5.12 ± 2.42 cm post-operatively, and 5.03 ± 2.29 cm at final follow-up (F = 79.36, P < 0.001). No obvious loss of correction occurred, according to the lack of significant differences in the sagittal balance parameters between post-operatively and the final follow-up in all patients (TK: 27.76 ± 6.50° vs. 28.45 ± 6.63°, TLK: 13.86 ± 6.65° vs. 14.42 ± 6.7°, LL: −20.58 ± 9.71° vs. −20.73 ± 10.27°, and SVA: 5.12 ± 2.42 cm vs. 5.03 ± 2.29 cm, all P > 0.05, respectively).

Conclusions

The modified posterior wedge osteotomy is an accepted surgical procedure for treating thoracolumbar kyphosis with ALs in AS and results in satisfactory local kyphosis correction, solid fusion, and good clinical outcomes.

Is Any Correlation Present Between the Severity of Syndesmophytes and Spinopelvic and Clinical Parameters in Advanced Ankylosing Spondylitis?

OBJECTIVE

The present study evaluated the severity of syndesmophytes and its correlation with the spinopelvic and clinical outcomes in patients with ankylosing spondylitis (AS).

METHODS

The data from 41 consecutive patients with AS who had undergone pedicle subtraction osteotomy surgery at our institution were reviewed. The computed tomography syndesmophyte score (CTSS), a novel method of evaluating the severity of syndesmophytes, was applied to assess the syndesmophytes of the whole, cervical, thoracic, and lumbar spine. The measured spinopelvic parameters included global kyphosis, sagittal vertical axis, lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The Oswestry disability index questionnaire, C-reactive protein, and erythrocyte sedimentation rate were used to evaluate the clinical outcome. The Pearson correlation test was performed to identify correlations between syndesmophyte severity and the spinopelvic and clinical parameters.

RESULTS

The Pearson correlation analysis demonstrated that the whole CTSS (WCTSS), cervical CTSS, thoracic CTSS, and lumbar CTSS (LCTSS) correlated significantly with each other (P < 0.05). All the CTSSs correlated positively with age, disease duration, and pelvic tilt (P < 0.05). In addition, both sagittal vertical axis and lumbar lordosis were significantly related to the WCTSS, cervical CTSS, and LCTSS (P < 0.05). The Oswestry disability index correlated negatively with the WCTSS (r = -0.312; P < 0.05), thoracic CTSS (r = -0.314; P < 0.05), and LCTSS (r = -0.343; P < 0.05).

CONCLUSIONS

In advanced AS, old age and a long disease duration are risk factors for the progression of syndesmophytes. The progression of syndesmophytes might contribute to spinal sagittal malalignment. With serious syndesmophytes, pelvic retroversion seems to be the major compensatory mechanism for spinal sagittal malalignment.

Impact of cervical range of motion on the global spinal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following pedicle subtraction osteotomy

BACKGROUND CONTEXT

The head's center of gravity (COG) plumb line (PL) and C7 PL could be simultaneously positioned over the pelvis in adult spinal deformity with normal cervical mobility. However, the position of the head in relation to the global spinal alignment has yet to be investigated in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis.

PURPOSE

The objective of this study was to analyze the position of head in relation to the global spinal alignment in AS-related thoracolumbar kyphosis.

STUDY DESIGN/SETTING

Retrospective single-center study.

PATIENT SAMPLE

AS patients who underwent lumbar pedicle subtraction osteotomy for thoracolumbar kyphosis from January 2010 to August 2016 were reviewed. Only patients with a visible ear canal on the preoperative, immediate postoperative, and final follow-up radiographs were included.

OUTCOME MEASURES

The chin-brow angle, cervical range of motion (ROM), lumbar lordosis (LL), thoracolumbar angle, thoracic kyphosis (TK), L1 pelvic angle, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), TK+LL+PI, PI-LL, maximal kyphosis (MK), deformity angular rate, T1 pelvic angle, T1 tilt, spinosacral angle, sagittal vertical axis (SVA) COG-C7, SVA COG-femoral head (FH), and SVA C7-S were evaluated. Data regarding the health-related quality of life, including the Oswestry disability index (ODI) and visual analogue scale (VAS)-back score, were also collected preoperatively, 2 years postoperatively, and at the latest follow-up.

METHODS

The cohort was divided into patients with occiput-trunk (OT) concordance or with OT discordance according to the SVA COG-C7 ≤30 mm or >30 mm, respectively. There was no funding in this study and there are no conflict of interest-associated biases.

RESULTS

A total of 43 patients (36 males and 7 females) with a mean age of 34.2 years (range, 18-59 years) were identified. There were 17 patients accompanied with OT concordance and 26 patients with OT discordance preoperatively. The cervical ROM was significantly lower (24.0° vs 56.1°, p<.001) and SVA COG-C7 was significantly larger (71.7 mm vs 7.4 mm, p<.001) in patients with OT discordance. Furthermore, the PT was larger (41.0° vs 33.5°, p=.010) in patients with OT discordance. After surgery, the whole cohort showed an improvement in LL (-8.6° vs -52.8°, p<.001). Moreover, the CBVA (25.4° vs 1.3°, p<.001) and SVA COG-C7 (46.2 mm vs 21.6 mm, p<.001) were significantly decreased following lumbar PSO. There were 13 patients accompanied with OT discordance postoperatively, and the cervical ROM was still lower (22.5° vs 42.8°, p=.024) in these patients. Postoperative PT was larger (26.5° vs 20.1°, p=.033) in the patients with OT discordance. At the latest follow-up, there were 17 patients accompanied with OT discordance. In these 17 patients, the cervical ROM was significantly lower (21.0° vs 47.0°, p=.001) and PT was significantly higher (26.2° vs 19.2°, p=.012). The ODI and VAS-back scores demonstrated no significant differences between the two groups preoperatively, 2 years postoperatively, or at the latest follow-up.

CONCLUSIONS

OT discordance in AS-related thoracolumbar kyphosis could be caused by the reduced cervical ROM. To maintain global spinal balance, the pelvis rotated further backward in response to the larger SVA COG-C7. Moreover, the larger SVA COG-C7 could be decreased after the lumbar PSO. Although there were radiographic differences between the patients with OT concordance and with OT discordance, there was no difference in clinical outcomes, and that a larger sample size and longer follow-up are needed.

[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.

Two-Level Osteotomy for the Corrective Surgery of Severe Kyphosis From Ankylosing Spondylitis: A Retrospective Series

STUDY DESIGN

Retrospective study.

OBJECTIVE

To describe the treatment results of patients with severe ankylosing spondylitis (AS) kyphosis who underwent two-level osteotomy and correction surgery.

SUMMARY OF BACKGROUND DATA

The best solution for the fixed kyphotic deformity of AS is corrective osteotomy. Many osteotomy options are available: pedicle subtraction osteotomy (PSO), Smith-Peterson osteotomy (SPO), and vertical column resection (VCR). These procedures all provide multiplanar deformity correction. Nevertheless, when the AS deformity is severe, an additional osteotomy site to get more correction, achieve more ideal, and smooth curvature of the spine than single osteotomy.

METHODS

From May, 2008 to August, 2016, 19 patients of severe AS kyphosis underwent two-level spinal osteotomy and correction surgery. The patients had an average kyphosis angle greater than 90°. The radiological features and clinical evaluation, including Oswestry Disability Index (ODI), visual analog scale (VAS), and Scoliosis Research Society (SRS)-22 components were assessed before surgery and at follow-up. The patients underwent either one-level PSO combined with one-level SPO (n = 9) or two-level PSO (n = 10).

RESULTS

The height was increased after surgery in all patients (P < 0.05). The median follow-up was 24 months. The kyphosis angle improved from 92.0 ± 16.6° to 30.0 ± 17.2°. The chin-brow vertical angle improved from 37.6 ± 19.2° to -0.6 ± 2.5°. The sacral slope improved from 3.9 ± 11.8° to 21.7 ± 7.4°. Sagittal imbalance improved from 241.4 ± 115.3 mm to 74.6 ± 48.5 mm (P < 0.05). Lumbar lordosis improved from -3.9 ± 20.8° to 29.4 ± 14.1° (all P < 0.05). There were significant improvements in the ODI, VAS, and all components of SRS-22 (all P < 0.05). All patients with pseudarthrosis (n = 5) underwent PSO + SPO and achieved satisfactory results. Six complications were observed perioperatively, but without permanent sequelae.

CONCLUSION

Two-level osteotomy and correction procedure can achieve satisfactory results in severe AS kyphosis. PSO + SPO could be a good option for patients with pseudarthrosis because of relatively easier and faster operation.

LEVEL OF EVIDENCE

4.

Intraoperative Multimodal Monitoring in Pedicle Subtraction Osteotomies of the Lumbar Spine: A Narrative Literature Review

The use of intraoperative multimodal monitoring (IOM) in spinal deformity surgeries is well documented. In particular, pedicle subtraction osteotomy (PSO), a corrective procedure for sagittal deformity of the spine, often involves IOM usage. By providing immediate feedback to the operating surgeon, IOM has the potential to eliminate or at least minimize the risk of iatrogenic neurological injury. However, despite the widespread usage of IOM, there is currently no standardization of IOM usage in complex spine surgeries, including lumbar PSOs, and decisions concerning IOM utilization are often driven by surgeon experience and preference. This creates a state of clinical equipoise, which is further complicated by the varying degrees of benefit that IOM has on patient outcomes depending on the operation and spinal levels involved. For instance, while IOM use in thoracic PSOs has been shown to be effective, there is no established consensus on the net impact of IOM use in PSOs of the lumbar spine. Although IOM has the potential to mitigate neurological damage, it also increases operation time and cost; thus, it should only be used in operations where it will have a net positive impact on patient outcomes. The question thus becomes whether PSO of the lumbar spine is one such operation. To address this, we examine the most frequently used IOM modalities and evaluate their current usage and efficacy in lumbar PSOs. Furthermore, we will also examine the utility of IOM for other surgeries of the lumbar spine, including corrective procedures for idiopathic scoliosis and degenerative scoliosis, and routine lumbar procedures, such as discectomies and decompression surgeries for foraminal and canal stenosis.

Complications of spinal osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis in 342 patients: incidence and risk factors

OBJECTIVE

To describe the incidence of complications in spinal osteotomy for thoracolumbar kyphosis caused by ankylosing spondylitis (AS) and to investigate the risk factors for these complications.

METHODS

From April 2000 to July 2017, 342 consecutive AS patients with a mean age (± SD) of 35.4 ± 9.8 years (range 17–71 years) undergoing spinal osteotomy were enrolled. Patients with complications within the 1st postoperative year were identified. Demographic, radiological, and surgical data were compared between patients with and without complications. The complications were classified into intraoperative and postoperative complications.

RESULTS

A total of 310 consecutive pedicle subtraction osteotomy (PSO) and 37 multiple Smith-Petersen osteotomy (SPO) procedures were performed in 342 patients. Overall, 47 complications were identified in 47 patients (13.7%), including 31 intraoperative complications and 16 postoperative complications. Patients with complications were older than those without (p = 0.006). A significant difference was observed in preoperative global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis (SVA), and the correction of these radiographic parameters between patients with and without complications (p < 0.05). Two-level PSO (p = 0.022) and an increased number of instrumented vertebrae (p = 0.019) were significantly associated with an increased risk of complications.

CONCLUSIONS

The overall incidence of complications was 13.7%. Age; preoperative GK, LL, and SVA; the correction of GK, LL, and SVA; 2-level PSO; and number of instrumented vertebrae were risk factors. Therefore, the potential risk of extensive surgeries with large correction and long fusion in older AS patients with severe GK should be seriously considered in surgical decision-making.

Does solid fusion eliminate rod fracture after pedicle subtraction osteotomy in ankylosing spondylitis-related thoracolumbar kyphosis?

BACKGROUND CONTEXT

Rod fracture (RF) has a negative impact on the surgical outcome of patients with ankylosing spondylitis (AS) after lumbar pedicle subtraction osteotomy (PSO). However, there is a paucity of published studies analyzing the risk factors for RF in PSO-treated patients with AS with thoracolumbar kyphosis.

PURPOSE

The objective of this study was to investigate the risk factors for RF after PSO for thoracolumbar kyphosis secondary to AS.

STUDY DESIGN/SETTING

This is a retrospective single-center study.

PATIENT SAMPLE

Patients with AS who underwent PSO for thoracolumbar kyphosis between January 2002 and December 2016 were included.

OUTCOME MEASURES

Demographic data, including age, sex, body mass index, and smoking status, were summarized. The surgical data analyzed included the levels of osteotomy, the fusion levels, the upper instrumented vertebra, the lower instrumented vertebra, the osteotomy site, the rod material, the rod diameter, and the rod contour angle (RCA). Radiographic parameters included the sagittal vertical axis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Radiographic parameters were measured at baseline, immediately after the operation, and at the final follow-up. Adequate ossification of the anterior longitudinal ligament (ALL) at the PSO level was defined by a total bony bridge. Adequate ossification of the ALL was also measured at baseline, immediately after the operation, and at the final follow-up.

METHODS

Patients with a minimum of 2 years' follow-up or patients who developed RF were enrolled in the study. Recruited patients were divided into the RF group and the no-RF group based on whether they developed RF. Patient demographics, operative data, radiographic parameters, and adequate ossification of the ALL were analyzed to determine the risk factors for RF. For patients with RF, the fusion status at the PSO level, the time course to the development of RF, the site of RF, and the corresponding solution were also recorded.

RESULTS

Rod fracture occurred in 11 (8.9%) of the 123 recruited patients. Solid fusion at the PSO level was found in all patients in the RF group. The average duration to the onset of RF was 31.4 months (range, 12-68 months). All RFs occurred at or immediately adjacent to the PSO level. The RCA was greater in the RF group than in the no-RF group (27.8° vs 22.9°, p=.031). A greater proportion of patients with a rod diameter of 5.50 mm were found in the RF group than in the no-RF group (100.0% vs 68.8%, p=.033). There was a larger proportion of patients with adequate ossification of the ALL at the final follow-up visit in the no-RF group than in the RF group (67.0% vs 27.3%, p=.018). Multivariate analyses demonstrated that the RCA (odds ratio, 1.174; 95% confidence interval, 1.018-1.354; p=.028) and adequate ossification of the ALL at the final follow-up visit (odds ratio, 0.079; 95% confidence interval, 0.014-0.465; p=.005) were independent factors for RF. Notably, revision surgery was performed among six patients, whereas conservative treatment was used for the remaining five patients.

CONCLUSIONS

In patients with AS after PSO for thoracolumbar kyphosis with solid fusion at the PSO level, the incidence of RF was 8.9%. Rod diameter was identified as a risk factor for RF. Furthermore, the RCA was identified as an independent risk factor for RF. In contrast, adequate ossification of the ALL around the PSO level at the final follow-up visit was identified as an independent protective factor for RF.

Radiologic and Pathological Investigation of Pseudarthrosis in Ankylosing Spondylitis: Distinguishing Between Inflammatory and Traumatic Etiology

OBJECTIVE

To investigate the pathogenesis of pseudarthrosis in ankylosing spondylitis (AS) based on the pathological analysis of specimens harvested during surgery.

METHODS

Radiographic and clinical data for 17 consecutive AS patients with pseudarthrosis were retrospectively analyzed. Meanwhile, the pathological analysis of specimens obtained during surgery was also performed.

RESULTS

In total, 18 extensive Andersson lesions were included. Pseudarthrosis located at the apical region were noted in 12 patients. Complete ossified anterior longitudinal ligaments above or below pseudarthrosis and fracture through posterior elements or facet joints were observed in 7 and 6 lesions, respectively. The most definitive pathological characteristic in all cases was proliferating hypovascular edematous fibrous tissue involving disc, bone-disc border, and vertebral body. Fibrinoid necrosis, necrotic bone fragments, hemosiderin deposits, and active subchondral osteogenesis were found, indicating trauma process. Mild perivascular collections of inflammatory cells were detected in only 2 cases.

CONCLUSION

AS-related pseudarthrosis is more likely to originate from mechanical trauma than inflammation. The above-mentioned radiological and histological findings showed that multiple mechanisms lead to the formation of pseudarthrosis. These mechanisms include excessive stress, insufficiency fracture, and an acute fracture involving a 3-column structure.

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.

Accuracy of Freehand Pedicle Screw Placement in Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: A Computed Tomography Investigation of 2314 Consecutive Screws

OBJECTIVE

To evaluate the accuracy and safety of freehand pedicle screw placement in surgical correction for thoracolumbar kyphosis caused by ankylosing spondylitis (AS).

METHODS

We retrospectively reviewed 266 consecutive patients with AS who underwent osteotomy for kyphosis correction with freehand screw insertion from January 1998 to April 2015 at our institution. A total of 2314 pedicle screws in 158 patients with AS with postoperative computed tomography scans were included in the study. Postoperative computed tomography was performed to classify accuracy of screws, using the established Gertbein classification (grade 0: no perforation, grade 1: perforation <2 mm, grade 2: perforation between 2 and 4 mm, and grade 3: perforation >4 mm). Patients were divided into 2 groups according to coronal Cobb angle: group A (n = 21, Cobb angle ≥10°), group B (n = 137, Cobb angle <10°).

RESULTS

Among the 2314 pedicle screws, 2168 pedicle screw placements were categorized as grade 0, 71 were grade 1, 51 were grade 2, and 24 were grade 3. Breaches occurred more frequently in L1-S1 than the thoracic spine (7.1% and 5.4%, respectively). T5 (25.0%) and S1 (17.7%) experienced the greatest breach rate, whereas T8, L1, and L3 had the lowest breach rate. The breach rate of group A was greater than that of group B (7.9% vs. 6.1%). None of the breaches resulted in either neurologic deficits or vascular complications.

CONCLUSIONS

Freehand pedicle screw placement can be performed safely with acceptable breach rate in patients with AS and thoracolumbar kyphosis.

Managing morbidity and treatment-related toxicity in patients with ankylosing spondylitis

AS is the prototypical member of the family of spondyloarthropathies, and is characterized by seronegativity, axial predominance and new bone formation, which underlie symptoms of inflammatory back pain, enthesopathy and extra-articular manifestations, including anterior uveitis, psoriasis and colitis. Patients with AS typically experience a wide variety of morbidities. These include both morbidities related to the disease itself—most prominently progressive, irreversible, structural damage to the axial or peripheral skeleton—and morbidities stemming from treatments for the disease, including toxicities from NSAID use, and increased risk of infections and immunogenicity concerns with biologics. AS is also associated with a number of comorbidities. We review the risks associated with AS, its comorbidities and its treatments, as well as strategies that can be used to mitigate these risks in patients with AS.

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.

Three column osteotomy for adult spine deformity: comparison of outcomes and complications between kyphosis and kyphoscoliosis

BACKGROUND

To compare the surgical outcomes and complications between kyphosis and kyphoscoliosis when using three-column osteotomies.

METHODS

Adult spine deformity (ASD) patients with three column osteotomies from March 2005 to December 2014 in our center were retrospectively reviewed. Pre- and postoperative standing postero-anterior and lateral radiographs of the entire spine were obtained. Scoliosis Research Society-22 questionnaire [SRS-22] and Oswestry Disability Index [ODI] were administered preoperatively, postoperatively (surveys within 2 months after surgery), and at final follow-up. Patients were assigned to one of two groups according to pre-operative coronal curve magnitude: (1) if coronal curve <10°, patients were assigned to kyphosis group (K group); (2) if coronal curve >40°, patients were assigned to kyphoscoliosis group (S group).

RESULTS

33 ASD patients were assigned to the kyphosis group (K group), of which 26 received PSO (pedicle subtraction osteotomy) and 7 VCR (vertebral column resection). 76 patients were assigned to kyphoscoliosis group (S group), of which 50 received PSO and 26 VCR. Patients in the K group were significantly older than in the S group (42.8 vs. 33.7 years, p < .05). Significantly longer OT (operation time) and more EBL (estimated blood loss) were observed in the S group as compared to K group (OT: 282 vs. 205 min, p < .05; EBL: 1827 vs. 1214ml, p < .05). No significant difference was noted for number of fusion levels between the groups (12.4 vs. 12.7, p > .05). Pre-operative radiographic parameters demonstrated no difference of GK (global kyphosis) and SVA (sagittal vertical axis) between the two groups (GK: 74.7° vs 76.2°, p > .05; SVA:53.2 vs. 55.7mm, p > .05). K group had larger KF than S group (26% vs. 15%, p < .05). Overall complication rate was higher in S group than in K group (30.3% vs. 18.2%, p < .05). No difference of neurological complication rates between the two groups (9.1% vs. 10.5%, p > .05).

CONCLUSIONS

Kyphoscoliosis group had less KF, GK correction and more OT, EBL and surgical complications when receiving three column osteotomies.

Transpseudarthrosis Osteotomy with Interbody Fusion for Kyphotic Spinal Pseudarthrosis in Ankylosing Spondylitis by a Single Posterior Approach: A Retrospective Study and a Brief Relevant Literature Review

Objective

To explore the safety and efficacy of transpseudarthrosis osteotomy with interbody fusion in the treatment of Ankylosing Spondylitis (AS) patients with kyphotic spinal pseudarthrosis by a single posterior approach.

Methods

Twelve consecutive patients with spinal pseudarthrosis underwent transpseudarthrosis osteotomy and interbody fusion with a polyetheretherketone (PEEK) cage by a single posterior approach. The operative time, intraoperative blood loss, and complications were recorded. Radiographic and clinical results were assessed preoperatively and at the final follow-up.

Results

The average operative time was 201.9 min and the mean blood loss was 817.5 ml. The visual analogue scale (VAS) improved significantly from 6.7 preoperatively to 1.1 at the final follow-up. The average correction of the segmental kyphosis at the level of the pseudarthrosis was 22.3°. Bony fusion was achieved in all patients, and there was no obvious loss of correction at follow-up.

Conclusion

Transpseudarthrosis osteotomy at the level of the pseudarthrosis can be safely performed and surgical repair of pseudarthrosis with interbody fusion by a single posterior approach was feasible.

Quality of life and correlation with clinical and radiographic variables in patients with ankylosing spondylitis: a retrospective case series study

Background

Previously, many studies have evaluated quality of life (QoL) in patients with ankylosing spondylitis (AS), however, none of them specifically investigated the correlation between pain-related disability measured by Oswestry Disability Index (ODI) and QoL in AS patients. In addition, the correlation between global kyphosis (GK) in lateral plain radiographs and QoL in AS patients remains unclear up to now. Therefore, this study aimed to evaluate QoL and correlation with clinical and radiographic variables in AS patients, especially to figure out the relationship about the pain-specific disability measured by ODI, GK and QoL.

Methods

From January 2008 to November 2015, two hundred and forty-five consecutive patients with an average age of 36.2 ± 10.9 years (range, 17–66 years) satisfying the Modified New York Criteria for AS from a single institution were enrolled. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI) and Bath Ankylosing Spondylitis Global score (BAS-G) were applied to assess the disease activity, functional status, spinal mobility and overall feeling of AS patients, respectively. ODI was recorded to evaluate low back pain-related disability. QoL was evaluated by the Short Form-36 (SF-36). According to global kyphosis (GK) measured on standing lateral full-spine radiographs, the patients were divided into two groups: mild kyphotic group (GK < 70°,n = 176) and severe kyphotic group (GK ≥ 70°,n = 69).

Results

The scores of BASDAI, BASFI, BASMI and ODI had significant negative correlations with all SF-36 subscale scores (P < 0.01). BASFI and BASMI scores of severe kyphotic group were much higher than those of mild kyphotic group, respectively (P = 0.005 and P = 0.001, respectively) and the score of physical function (PF) subscale in severe kyphotic group was significantly higher than that in mild kyphotic group (P = 0.046) as well. Notably, the scores of ODI, BASFI and BASMI were the major predictors of PF subscale score of SF-36.

Conclusions

Poor QoL is significantly correlated with high disease activity, poor functional status and decreased spinal mobility in AS. GK is significantly associated with functional status, spinal mobility and QoL in AS patients. ODI, BASFI and BASMI are the major predictors of PF subscale of SF-36.

Sagittal Vertical Axias, Spinosacral Angle, Spinopelvic Angle, and T1 Pelvic Angle: Which Parameters May Effectively Predict the Quality of Life in Ankylosing Spondylitis Patients With Thoracolumbar Kyphosis?

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

To identify the relationship between global sagittal alignment and health-related quality of life (HRQoL) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis.

SUMMARY OF BACKGROUND DATA

Little data are available on correlation between global sagittal alignment and HRQoL in AS.

MATERIALS AND METHODS

A total of 107 AS patients were included in this study. The radiographic parameters were measured on lateral radiographs of the whole spine, including sagittal vertical axias (SVA), spinosacral angle (SSA), spinopelvic angle (SPA), and T1 pelvic angle (TPA). HRQoL was assessed using the oswestry disability index questionnaire, the bath ankylosing spondylitis disease activity index, the bath ankylosing spondylitis functional index, and short form-36 questionnaire. The patients were divided into 2 groups: group A (n=76, global kyphosis≤70 degrees), group B (n=31, global kyphosis>70 degrees). Statistical analysis was performed to identify significant differences between these 2 groups. In addition, correlation analysis and multiple regression analysis between radiologic parameters and clinical questionnaires were conducted.

RESULTS

With respect to SVA, SSA, SPA, TPA, and HRQoL scores, significant differences were observed between 2 groups (P<0.05). Also, SVA, SSA, SPA, and TPA were significantly related to HRQoL. Multiple regression analysis revealed that SVA, SSA, SPA, and TPA were significant parameters in the prediction of HRQoL in AS patients with thoracolumbar kyphosis. Of note, HRQoL related much more to SSA and SPA than SVA and TPA.

CONCLUSIONS

AS patients with moderate and severe deformity were demonstrated to be significantly different in terms of SVA, SSA, SPA, TPA, and HRQoL. Moreover, SVA, SSA, SPA, and TPA correlated with HRQoL significantly. In particular, SSA and SPA could better predict HRQoL than SVA and TPA in AS patients with thoracolumbar kyphosis.

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.

One-stage posterior grade 4 osteotomy and bone graft fusion at pseudarthrosis for the treatment of kyphotic deformity with Andersson lesions in ankylosing spondylitis

OBJECTIVES

The optimal surgical procedure for treating kyphotic deformity with Andersson lesions (ALs) in ankylosing spondylitis (AS) patients is controversial. The one-stage posterior osteotomy and bone graft fusion approach is rarely reported. The aim of the present study was to report a new surgical procedure involving one-stage posterior grade 4 osteotomy and bone graft fusion for the treatment of kyphotic deformity with ALs in AS.

PATIENTS AND METHODS

Eleven patients with ALs in AS were enrolled. One-stage posterior grade 4 osteotomy and bone graft fusion was performed in all patients. Frankel classification and visual analog scale (VAS) were used to evaluate neurologic deficit and the level of back pain pre- and postoperatively, respectively. Radiographic and clinical outcomes were assessed with a mean of 31.5 months follow-up.

RESULTS

Local kyphosis was corrected from 19.1° to 0.5° after surgery with a mean correction rate of 95%. One Frankel C and 5 Frankel D patients changed to Frankel D and Frankel E, respectively. VAS was reduced from 6.7 to 0.27 at final follow-up. Bone graft fusion was observed at an average of 4.3 months and solid bony fusion was achieved at final follow-up. Average operation time and blood loss were 268.6min and 1009ml, respectively. Three patients developed dural tear complications. There were no neurological or instrumentation complications reported or observed at final follow-up.

CONCLUSION

One-stage posterior grade 4 osteotomy and bone graft fusion is an optional surgical procedure to treat ALs in AS patients. This approach results in reduced blood loss and operation time, satisfactory correction of local kyphosis, and good safety. Successful fusion and good clinical outcomes can also be achieved.

Posterior wedge osteotomy and debridement for Andersson lesion with severe kyphosis in ankylosing spondylitis

Background

Andersson lesion is a well-known complication in ankylosing spondylitis. Recently, owing to the worry about the healing of fracture, some scholars advocated additional anterior surgery or other procedures were necessary, which increase the risk of the nerve injury. The purpose of this study is to introduce our experience and to explore the efficacy and feasibility of posterior wedge osteotomy and debridement through Andersson Lesion for surgical treatment of severe kyphosis in ankylosing spondylitis.

Methods

From January 2012 to January 2014, a retrospective study of 14 Andersson lesion patients with severe kyphosis in ankylosing spondylitis treated with surgery was completed with an at least 2-year follow-up. The debridement procedure, before posterior wedge osteotomy in posterior approach, must scrape all sclerosis bone until healthy cancellous bone appears. Radiographic and clinical results and complications were assessed with an average follow-up of 24 months. The CT scan was obtained preoperatively and at the final follow-up to assess the displacement of the fracture preoperatively, the safety of screw insertion, the healing of the fracture at the final follow-up. The Bridwell interbody fusion grading system was used to assess the healing of the fracture.

Results

Local kyphosis was substantially corrected from 51.7 ± 15.6 to 7.1 ± 19.5, with a mean correction of 44°. The global kyphosis (GK) changed from 60.6 ± 28.3 to 20.3 ± 10.3 (P = 0.000). The mean VAS back pain scores decreased from 6.7 ± 0.8 preoperatively to 0.75 ± 0.6 after a 2-year follow-up (P = 0.000). The ODI score improved from 60.56 ± 15.1% preoperatively to 23.46 ± 8.2% after a 2-year follow-up (P = 0.000). The CT scan showed solid fusion at the level of the AL, and no internal fixation loose. All patients achieved grade 1 fusion. No major complication occurred.

Conclusions

The posterior wedge osteotomy and debridement through AL can be used to correct the severe kyphosis in ankylosing spondylitis, achieving favorable clinical outcomes, good fusion, and satisfactory deformity correction.

Does the position of conus medullaris change with increased thoracolumbar kyphosis in ankylosing spondylitis patients?

To date, only a few reports described the potential factors influencing the position of conus medullaris. One previous study revealed no significant change of conus locations in patients with idiopathic scoliosis; however, the effect of ankylosing spondylitis (AS)-related thoracolumbar kyphosis on conus position remains unexplored. Therefore, we aimed to investigate the variation of conus medullaris terminations in patients with thoracolumbar kyphosis secondary to AS when compared with normal subjects, and evaluated the relationship between conus positions and the magnitude of kyphosis. In this study, MR images of 96 AS patients with thoracolumbar kyphosis, including 86 males and 10 females with an average of 34.6 years (range, 17-65 years), and 100 age-matched normal controls were reviewed to determine the conus terminations in relation to spinal levels. Sagittal parameters of the AS group measured on radiograph included: global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), and thoracolumbar junction (TLJ). Finally, conus tips located at the mean level of the lower 3rd of L1 in both groups, there was no significant difference of the conus distributions between AS and control group (P = 0.49). In addition, conus medullaris displayed similar positions in AS patients among various apical region groups (P = 0.88), and no significant difference was found when AS population was stratified into GK ranges of 30° (P = 0.173). Also, no remarkable correlation of the conus positions with GK (r = -0.15, P = 0.15), TK (r = -0.10, P = 0.34), LL (r = -0.10, P = 0.32), and TLJ (r = -0.06, P = 0.54) was identified. This study showed the conus terminations displayed a wide range of distributions in AS patients with thoracolumbar kyphosis, which was similar to normal subjects. Moreover, the conus located at a relatively fixed position and would not be affected by the change of kyphosis magnitude, which is an important knowledge that surgeons should acquire in surgical correction of the deformity in these patients.

Evaluating a Posterior Approach for Surgical Treatment of Thoracolumbar Pseudarthrosis in Ankylosing Spondylitis

STUDY DESIGN

Retrospective study of a posterior approach for surgical treatment of thoracolumbar pseudarthrosis in ankylosing spondylitis (AS).

OBJECTIVE

The aim of the current study was to report the surgical results of symptomatic thoracolumbar pseudarthrosis in AS through a posterior approach.

SUMMARY OF BACKGROUND DATA

Spinal pseudarthrosis is a well-known complication in AS. The condition may complicate with mechanical back pain, spinal deformity, and sometimes neurological deficits. Conservative treatment often fails in this situation and surgical treatment is required. However, the optimal surgical procedure for this condition is still controversial.

METHODS

From January 2006 to December 2011, 12 AS patients with spinal pseudarthrosis at the thoracolumbar segment were treated surgically after failure of >3 months conservative treatment. The indications for surgery were persisting back pain in all patients, combined with neurological deficits in 4 patients and spinal deformities in 3 patients. Transforaminal or transpedicular debridement of the pseudarthrosis at the anterior column was performed from a posterior approach. After complete debridement, bone graft at the anterior open wedge defect of the pseudarthrosis was performed from a posterior approach. Posterior pedicle screws were placed for fixation. Clinical and radiographic outcomes were assessed with an average follow-up of 28 months (range, 24-36 mo).

RESULTS

The persistent back pain obtained significant relief in all cases after surgery. Four patients with neurological deficits showed complete recovery of neurological function at follow-up. The spinal deformities in 3 cases obtained correction. Solid bony fusion was achieved in all cases, and there was no correction loss at follow-up.

CONCLUSIONS

In AS with symptomatic thoracolumbar pseudarthrosis, a posterior transforaminal or transpedicular approach can provide circumferential stability, anterior bone graft, and neurological decompression simultaneously. A supplemental anterior approach may be avoided by this method.

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.

Halo Gravity Traction Is Associated with Reduced Bone Mineral Density of Patients with Severe Kyphoscoliosis

Background. Halo gravity traction (HGT) is one of the most commonly used perioperative techniques for the treatment of severe kyphoscoliosis. This study was to explore the influence of HGT on the BMD of these patients. Methods. Patients with severe kyphoscoliosis treated by preoperative HGT for at least 2 months were included. Patients' BMD were assessed by dual-energy X-ray absorptiometry at lumbar spine (LS, L2–L4) and femur neck (FN) of the nondominant side. The weight and duration of traction, as well as baseline characteristics, were recorded. Results. Twenty patients were recruited. The average traction duration was 77.9 ± 13.0 days while the mean traction weight was 39.9% ± 11.1% of total body weight. Remarkable decrease of BMD was observed at LS of 17 (85%) patients and at FN of 18 (90%) patients. After HGT, 75% of patients were found to have osteoporosis, the incidence of which was significantly higher than that before HGT (35%). The correlation analysis revealed BMD reduction was only significantly correlated with the traction duration. Conclusions. The current study showed that preoperative HGT can have obvious impact on the BMD. The BMD reduction is associated with traction duration, suggesting that long traction duration may bring more bone mineral loss.

Treatment of kyphosis in ankylosing spondylitis by osteotomy through the gap of a pathological fracture: a retrospective study

Background

Surgical interventions are commonly advocated for correcting kyphotic deformities and relieving severe back pain in ankylosing spondylitis (AS) patients. The aim of this study was to evaluate the clinical outcome of osteotomy performed through the gap of a pathological fracture for the treatment of kyphosis in ankylosing spondylitis and to introduce the key points of this novel surgical approach.

Methods

From January 1, 2010, to December 31, 2014, 13 consecutive AS patients who were treated with osteotomy through the fracture gap were retrospectively reviewed. Patients underwent the radiographic assessment of sagittal balance parameters. Visual analog scale (VAS) scores were used to assess improvement in back pain.

Results

The average follow-up time was 2 years and 1 month. The median operation time was 280 min (range, 220–460 min). The mean blood loss was 1100 mL (range, 820–1300 mL). No major acute complications such as death or complete paralysis occurred. There were no neurologic complications or cerebrospinal fluid leaks in any patient. One patient had postoperative wound infection, which subsided after a switch of antibiotics. The global kyphosis Cobb angle of patients decreased from the preoperative 55.8° ± 11.0° to 23.2° ± 6.7° (P < 0.001) after surgery. The C7 plumb line was used to assess global balance; its relationship with the posterosuperior corner of the sacrum decreased from 166 ± 37 mm to 111 ± 20 mm (P < 0.001). The thoracolumbar kyphosis Cobb angle decreased from 51.0° ± 9.9° to 21.6° ± 11.0° (P < 0.001). VAS scores for back pain decreased from 7.2 ± 1.2 to 2.1 ± 1.1 (P < 0.001). Lumbar lordosis increased from 5.7° ± 23.2° to 10.5° ± 29.2° (P = 0.001).

Conclusions

Osteotomy through the pathological fracture gap is a safe and effective surgical procedure for kyphosis correction and improvement of back pain in AS patients with pathological fractures. A significant kyphosis correction and improvement of back pain can be achieved with this surgical procedure.

Symptomatic pseudarthrosis in ochronotic spine: case report

In this study the authors report the first example of spinal pseudarthrosis in a patient with ochronosis, and they describe the application of posterior-only 360° surgery as an alternative approach to combined anterior-posterior surgery in the management of pseudarthrosis of an ankylosed spine, regardless of its etiology. Spinal involvement in ochronosis produces loss of flexibility and ankylosis of thoracic and lumbar segments. Pseudarthrosis is a serious complication of the diseases that present with ankylosis of the spine. However, its occurrence in ochronotic spine has not been reported previously. Evaluation of progressive paraparesis in a 68-year-old man with ochronosis revealed pseudarthrosis at the T11-12 level. Circumferential dural sac decompression, debridement of the disc space, interbody fusion, and screw-rod fixation were all done via a posterior-only approach. Postoperatively the patient exhibited a marked recovery in terms of pain and neurological status. At the 3-month follow-up, he was able to walk independently. Ochronosis should be included in the etiology of pseudarthrosis. With aggravation of back pain and the appearance of neurological deficits in an already stable patient with any ankylosing disease, pseudarthrosis should be suspected. Furthermore, single-stage, 360°, posterior-only surgery may obviate the need for single-stage or staged anterior-posterior surgical intervention in patients with pseudarthrosis of the thoracic and lumbar spine.