Osteotomies in the treatment of spinal deformities: indications, classification, and surgical planning

Anesthetic management of folders with severe kyphosis in ankylosing spondylitis: a single-center retrospective case series study

Background

Ankylosing spondylitis (AS) is a progressive inflammatory disease causing severe kyphosis, which complicates surgical management and increases complication risks. This study aims to analyze the characteristics of severe kyphosis in AS and explore methods to optimize perioperative management and reduce complications.

Methods

We conducted a retrospective analysis of clinical data from five patients with severe kyphosis in AS who underwent surgery between October 2017 and February 2022. The patients had a mean age of 40.20 ± 8.50 years. The analysis included pathophysiological changes in folded patients and perioperative multidisciplinary intervention guidance. It also covered strict preoperative anesthetic evaluations, establishing an optimal fluid pathway during surgery, precise anesthetic monitoring and management, and applying postoperative multimodal analgesia and rehabilitation exercises to optimize perioperative anesthetic management.

Results

Preoperative cardiopulmonary function exercises were required to ensure patients could withstand surgery and anesthesia. Awake fiberoptic tracheal intubation was used to ensure airway safety and anesthesia. Hemodynamic evaluation and management were conducted using PICCO monitoring. Somatosensory evoked potentials (SSEP) and myogenic motor evoked potentials (MMEP) were utilized for neural axis monitoring. Hypothermia was designed to protect the spinal cord. To prevent massive blood loss, controlled hypotension and autotransfusion were implemented.

Conclusion

The correction operation of severe spinal kyphosis is complex and requires a detailed anesthesia plan. Optimizing the management of difficult airways and respiratory regulation, guiding circulation and fluid management through comprehensive monitoring, avoiding factors that aggravate complications, improving postoperative analgesia, and encouraging active rehabilitation exercises are crucial goals for perioperative anesthesia management.

An update on improvement and innovation in the management of adult thoracolumbar spinal deformity

Adult spinal deformity (ASD) is a spectrum of abnormalities of the thoracic and lumbar spine and has an increasing prevalence. It is associated with significant physical and mental disability in symptomatic patients. Given the increased rates and the morbidity associated with this disease, novel innovation in the diagnosis and treatment of such deformity is required. The SRS-Schwab classification system described coronal scoliotic deformity with sagittal modifiers. Other parameters, such as the sagittal vertical axis, pelvic tilt, T1 pelvic angle, pelvic incidence and lumbar lordosis attempted to quantify global sagittal balance. More recently, a focus on more patient specific parameters has been targeted to improve patient outcomes. The Roussouly classification system attempted to predict sagittal alignment parameters based on fixed parameters of the pelvis. Others determined the parameters based on patient age. Technological advances have also enhanced our understanding of ASD. Long cassette films and automated analyses have allowed standardization of these measurements across physicians. 3D printing has been used as an adjunct for both surgical planning and implants, both generic and patient specific, to improve outcomes. With these, advances in minimally invasive approaches have allowed ASD correction with lower complications and blood loss. Intraoperative navigation and the use of robotics has allowed improved accuracy in the care of these patients. Development of complex osteotomies have allowed for correction of advanced deformity. Fusion, however, is the ultimate goal of surgical ASD correction. Advances in biologics such as the use of recombinant Human Bone Morphogenetic Protein-2 have been used to improve fusion rates and combat pseudoarthrosis. Finally, post-operative advances in ASD patient care with emphasis on enhanced recovery after surgery has allowed improvements in hospital length of stay and pain scores. ASD is becoming a more ubiquitous diagnosis for spine surgeons with an increasing aging population. Improvement in the understanding of the diagnosis, spinopelvic parameters, imaging techniques, and post operative care are all aimed toward helping patients in whom care can be extremely difficult. Further study in ASD patient care will target advanced innovation to provide optimal treatment to these patients and allow for best possible outcomes.

A New Minimally Invasive Technique for Thoracolumbar/Lumbar Focal Kyphosis Due to Osteoporotic Vertebral Fracture: A Case Report

Osteoporotic vertebral fractures are common fractures in the elderly population and are often associated with low back pain and disruption in daily living activities. Reconstruction surgeries, such as corpectomy, are among the treatment options for these conditions. However, a corpectomy requires a longer surgical procedure and involves a significant amount of blood loss. We present the case of an 80-year-old woman with severe low back pain due to an L2 fracture and focal kyphosis treated with a novel minimally invasive technique. The patient underwent anterior and posterior surgery in the right decubitus position using a C-arm-free technique. Hyperlordotic cages were inserted in the upper and lower disc space via a lateral approach, while percutaneous pedicle screws were inserted from a posterior approach. These procedures were performed simultaneously under navigation guidance only.

[Surgical treatment of kyphosis in children and adolescents]

OBJECTIVE

Correction of a pathological kyphosis to restore a balanced, low-pain or pain-free and load-bearing spine.

INDICATIONS

Pronounced sagittal imbalance, progressive kyphosis despite conservative therapy, and neurological deficits are indications for surgery. Further surgical indications are severe therapy-resistant complaints and/or psychologically burdening cosmetic impairment. The guidelines for surgical indications are kyphosis angles of 75-80° thoracic and 30-50° lumbar.

CONTRAINDICATIONS

No specific, but general contraindications for surgical treatment.

SURGICAL TECHNIQUE

Depending on the characteristics of the kyphosis, different surgical techniques are used. Rod-screw systems are mainly used, and surgery is primarily performed by shortening the spinal column from posterior using a wide variety of techniques. In individual cases, this can be combined with ventrally mobilizing, resecting, or straightening techniques.

POSTOPERATIVE MANAGEMENT

The aim of surgical treatment is to achieve a primarily stable and weight-bearing spine. Regular wound control as well as stabilizing physiotherapy during follow-up are essential. Postoperatively, initially abstaining from sports; later physical activity is encouraged under professional guidance.

RESULTS

The literature shows very good corrective results in children and adolescents. The technical procedures are associated with a low and acceptable complication rate. Over the course of time, these patients must be monitored in order to detect possible long-term complications such as junctional kyphosis or pseudarthrosis.

Pulmonary and clinical outcomes of patients with severe rigid scoliosis and type I respiratory failure treated with halo-pelvic distraction

BACKGROUND

The severe rigid scoliosis patients with type I respiratory failure could not tolerate complicated corrective surgery. Preoperative halo-pelvic distraction (HPD) is used to reduce the curve magnitude and improve the pulmonary function before surgery. The present study aimed to retrospectively analyze the pulmonary and clinical outcomes of preoperative HPD in severe rigid spinal deformity with type I respiratory failure.

METHODS

Eighteen cases of severe rigid scoliosis and type I respiratory failure treated with preoperative HPD and corrective surgery for spinal deformity between 2016 and 2018 were retrospectively reviewed. Patient demographics, major coronal curve and kyphosis, correction rates, heights, pulmonary function, distraction time, and postoperative neurological complications were recorded for all cases.

RESULTS

The averaged duration of distraction was 9.1 ± 2.3 months. The coronal curve was corrected from 168° ± 14° to 58° ± 11° at the end of HPD. The kyphosis curve reduced from 151° ± 29° to 65° ± 10°. Meanwhile, the mean stand body height increased by 23.9 ± 5.3 cm. Significantly increased mean FVC (1.52 ± 0.43 L vs. 0.95 ± 0.44 L) and improved percent-predicted values for FVC (37 ± 10% vs. 23 ± 9%) were observed after HPD. The pressure of oxygen (PaO2) increased from 54.5 ± 2.0 to 84.8 ± 4.7 mmHg. Scoliosis and kyphosis curve, respectively, averaged 48 ± 8°and 30 ± 14° after final fusion and instrumentation, with a mean correction of 71% and 80%, respectively. No severe complication occurred during the distraction.

CONCLUSIONS

HPD may be useful for severe rigid scoliosis patients with type I respiratory failure. Pulmonary functions in patients with severe rigid scoliosis can be significantly improved by HPD. They are then better able to tolerate complicated corrective surgery.

L5 pedicle subtraction osteotomy maintains good radiological and clinical outcomes in elderly patients with a rigid kyphosis deformity: a more than 2-year follow-up report

PURPOSE

L5 pedicle subtraction osteotomy (PSO) is a demanding technique; thus, PSOs are usually performed at the L3/L4 level to correct the lack of lumbar lordosis. Mid- to long-term improvements in clinical outcomes after L5 PSO are unknown. We aimed to determine the efficacy and safety of L5 PSO for rigid kyphosis deformities.

METHODS

We retrospectively reviewed the records of 57 patients with a rigid kyphosis deformity (mean age: 68 years) who underwent extensive corrective surgery incorporating PSO with a > 2-year follow-up. Radiographic parameters, postoperative complication rates, and the Oswestry Disability Index (ODI) scores were compared in the L5, L4, and L1-3 PSO groups preoperatively and at 1, 2, and 5 years postoperatively.

RESULTS

There were 12, 25, and 20 patients in the L5, L4, and L1-3 PSO groups, respectively. Significant between-group differences were found in preoperative L4-S1 lordosis (L5:L4:L1-3 PSO groups =  - 8.9°:8.9°:16.2°, P < 0.001). The surgeries improved the postoperative spinopelvic alignment (similar in all groups). There was no significant between-group difference in the postoperative complication rate; no irreversible complications occurred. In the L5 PSO group, there was one case of a common iliac vein injury. The ODI scores improved postoperatively in all groups; this was maintained for 5 years postoperatively.

CONCLUSION

L5 PSO for L4-5/L5 kyphosis deformities resulted in adequate correction and ODI improvement, which were maintained up to 5 years postoperatively. The surgical invasiveness, complication rates, and long-term prognosis associated with L5 PSO were similar to those of PSOs performed at other levels.

Modified grade 4 osteotomy for the correction of post-traumatic thoracolumbar kyphosis: A retrospective study of 42 patients

Many surgical procedures have been developed for the treatment of post-traumatic thoracolumbar kyphosis. But there is a significant controversy over the ideal management. The aim of this study was to illustrate the technique of modified grade 4 osteotomy for the treatment of post-traumatic thoracolumbar kyphosis and to evaluate clinical and radiographic results of patients treated with this technique.From May 2013 to May 2018, 42 consecutive patients experiencing post-traumatic thoracolumbar kyphosis underwent the technique of modified grade 4 osteotomy, and their medical records were retrospectively collected. Preoperative and postoperative sagittal Cobb angle, visual analog scale (VAS), Oswestry disability index (ODI), and American Spinal Injury Association (ASIA) were recorded. The average follow-up period was 29.7 ± 14.2 months.The operation time was 185.5 ± 26.8 minutes, the intraoperative blood loss was 545.2 ± 150.1 mL. The Cobb angles decreased from 38.5 ± 3.8 degree preoperatively to 4.2 ± 2.6 degree 2 weeks after surgery (P < .001). The VAS reduced from 6.5 ± 1.1 preoperatively to 1.5 ± 0.9 at final follow-up (P < .001), and the ODI reduced from 59.5 ± 15.7 preoperatively to 15.9 ± 5.8 at final follow-up (P < .001). Kyphotic deformity was successfully corrected and bony fusion was achieved in all patients. Neurologic function of 7 cases was improved to various degrees.Modified grade 4 osteotomy, upper disc, and upper one-third to half of pedicle are resected, is an effective treatment option for post-traumatic thoracolumbar kyphosis. However, the long-term clinical effect still needs further studies.

Posterior Grade 4 Osteotomy With Vertebral Shortening Is Effective for the Treatment of Kyphosis Associated With Vertebral Discitis/Osteomyelitis

Background

In the retrospective study of a prospectively maintained database, we present a case series of patients with kyphotic deformity secondary to spinal infection treated using a posterior-only approach with 3-column shortening and posterior instrumentation.

Methods

This is a case series of patients presenting with postural deformity and sagittal imbalance treated consecutively by 1 surgeon between 2012 and 2014. Clinical assessments and radiographic evaluations were made preoperatively and at 12- and 24-month postoperative follow-ups. All patients underwent computed tomography 24 months after surgery to evaluate spinal fusion.

Results

The study included 5 patients with a mean age of 50 years (range, 32-60 years). Three patients had comorbidities. Three patients were classified as American Spinal Injury Association (ASIA) grade C and were not ambulatory; 2 were ASIA grade D. At follow-up, all patients were ambulatory and classified as ASIA grade E. Kyphosis was corrected from a preoperative mean of 32° (range, 15°-58°) to 10° (range, 1°-42°) at the 2-year follow-up. A mean improvement of 22° and 75% reduction in kyphosis was obtained with fixation 2 levels above and below the lesion. Interbody fusion was observed in all patients. No major complications occurred during surgery.

Conclusions

Posterior grade 4 osteotomy with vertebral shortening can be performed safely in patients with kyphosis associated with vertebral discitis/osteomyelitis in the thoracolumbar region. The single approach allowed the surgeon to debride the infection, correct the kyphosis, decompress the spinal canal, and stabilize the spine.

Level of Evidence

4.

Sagittal Spinal and Pelvic Alignment in Middle-Aged and Older Men and Women in the Natural and Erect Sitting Positions: A Prospective Study in a Chinese Population

Background

This prospective study aimed to compare the sagittal spinopelvic parameters in the erect and natural sitting positions in healthy middle-aged and older men and women in a Chinese population.

Material/Methods

Ninety healthy middle-aged and older men and women underwent lateral whole spinal radiography in the natural and erect sitting positions. The radiographic sagittal spinopelvic parameters were measured. They included the sagittal vertical axis (SVA), the T1 pelvic angle (TPA), the pelvic incidence (PI), the pelvic tilt (PT), the sacral slope (SS), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), the T1 slope (T1S), cervical lordosis (CL), and lumbar lordosis (LL).

Results

In the natural sitting position, LL decreased by 14.5°, TK and TLK increased by 3.2° and 2.5°, respectively, PT increased by 10.3°, T1S increased by 6.9°, and CL increased by 3.4° compared with the erect position. In the natural sitting position, the mean forward-moving SVA was 33.4 mm, and the C2–C7 SVA was 6.1 mm. Men had a larger LL and smaller PT than the women when sitting in the erect position, and a greater TK, T1S, and C2–C7 SVA than women when sitting in the natural position.

Conclusions

In the natural sitting position, a reduction in LL was associated with TK, SVA and PT increased, and there were differences between men and women. The characteristics of spinopelvic alignment in healthy older adults should be considered when planning corrective spinal surgery.

Key Role of Preoperative Recumbent Films in the Treatment of Severe Sagittal Malalignment

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if severe sagittal malalignment (SM) patients without fixed deformities require a three-column osteotomy (3CO) to achieve favorable clinical and radiographic outcomes.

SUMMARY OF BACKGROUND DATA

3CO performed for severe SM has significantly increased in the last 15 years. Not all severe SM patients require a 3CO.

METHODS

Severe SM patients (sagittal vertical axis [SVA] >10 cm) who underwent deformity correction between 2002 and 2011. Patients with <33% change in their lumbar lordosis (LL) on a preoperative supine radiograph were classified as stiff deformities, whereas those with ≥33% change were categorized as flexible deformities. The clinical/radiographic outcomes were assessed at minimum two years postoperatively.

RESULTS

Seventy patients met the inclusion criteria, 35 patients with flexible and 35 with stiff deformities. Eighteen flexible-deformity patients underwent a 3CO versus 22 stiff-deformity patients. The remaining patients in each group underwent spinal realignment without a 3CO. The flexible-deformity patients not undergoing a 3CO had overall improvement in all sagittal radiographic parameters. Preoperative LL (22°), LL-pelvic incidence (PI) mismatch (43), SVA (17 cm), and pelvic tilt (PT, 34°) improved to 46°, 18, 6 cm, and 26°, respectively, p < .05. Flexible-deformity patients who underwent a 3CO also had overall improvement in all radiographic parameters. Preoperative LL (8.5°), LL-PI mismatch (47), SVA (19 cm), and PT (37°) improved to 39°, 15, 7 cm, and 24°, respectively (p < .05). Stiff-deformity patients who underwent a 3CO had statistically significant improvement in all radiographic parameters. However, stiff-deformity patients who did not undergo a 3CO had suboptimal improvement in all radiographic parameters, except for SVA (14 cm-9 cm, p < .05). Flexible patients who did not undergo a 3CO had statistical improvement in the SRS domains of function and self-mage as well as in their ODI scores (p < .05).

CONCLUSION

Severe SM that is flexible can be corrected without a 3CO without compromising clinical and radiographic outcomes.

LEVEL OF EVIDENCE

Level III.

Evidence-based Care Bundles for Preventing Surgical Site Infections in Spinal Instrumentation Surgery

STUDY DESIGN

A retrospective study, using prospectively collected data.

OBJECTIVE

The aim of this study was to evaluate the impact of evidence-based care bundles for preventing surgical site infections (SSIs) in spinal instrumentation surgery.

SUMMARY OF BACKGROUND DATA

About half of all SSIs are preventable via evidence-based methods. For successful SSI prevention, the bacterial load must be minimized, and methicillin-resistant Staphylococcus aureus (MRSA) protection must be maximized. However, it is difficult to cover all of these requirements by single preventative method.

METHODS

We screened consecutive patients scheduled for spinal instrumentation surgeries at a single tertiary referral hospital for high surgical, SSI, and MRSA colonization risks. Evidence-based care bundles were implemented for high-risk patients and included 1) additional vancomycin prophylaxis, 2) diluted povidone-iodine irrigation, and 3) nasal and body decontamination. Patient demographics, comorbidities, operative features, and SSIs reported to the Japanese Nosocomial Infections Surveillance system were prospectively obtained in the same method by the same assessor and were used for the analyses. The results were compared before and after the application of the bundle.

RESULTS

There were 1042 spinal instrumentation surgeries (741 before and 301 after care bundles) performed from November 2010 to December 2015. Of 301 surgeries, 57 cases (18.9%) received care bundles. There were no significant differences in patient backgrounds before and after the intervention. The SSI rate decreased significantly from 3.8% to 0.7% (P < 0.01) after the intervention, with an overall 82% relative risk reduction. A significant protective effect was observed in the multivariate analysis (adjusted odds ratio 0.18, 95% confidence interval: 0.04-0.77, P = 0.02). There were no MRSA-related SSIs among those that received care bundles, even though MRSA was the predominant pathogen in the study population.

CONCLUSION

Evidence-based care bundles, applied in selected high-risk spinal instrumentation cases, minimized bacterial load, maximized MRSA protection, and significantly reduced SSI rates without topical vancomycin powder.

LEVEL OF EVIDENCE

4.

Modified grade 4 osteotomy for kyphosis due to old osteoporotic vertebral compression fractures: Two case reports

RATIONALE

The kyphosis caused by old osteoporotic vertebral compression fracture usually requires osteotomy to correct it. Various osteotomy techniques have been reported, but each has its own advantages and disadvantages.

PATIENT CONCERNS

We reviewed 2 cases of old osteoporotic vertebral compression fractures with kyphosis in our hospital. One patient complained of persistent low-back pain, another patient complained of low-back pain and weakness of both lower extremities.

DIAGNOSIS

Old osteoporotic vertebral compression fractures with kyphosis were diagnosed based on computer tomography and magnetic resonance imaging.

INTERVENTIONS

We performed modified grade 4 osteotomy for 2 patients.

OUTCOMES

Both patients said significant improvement in preoperative symptoms, and x-ray showed that the kyphosis was corrected. Both patients were satisfied with the treatment at the last follow-up, and the kyphosis was not aggravated.

LESSONS

Modified grade 4 osteotomy is an effective option for the treatment of old osteoporotic fracture with kyphosis. It can restore the spine sequence and achieve better clinical result.

A Classification for Kyphosis Based on Column Deficiency, Curve Magnitude, and Osteotomy Requirement

BACKGROUND

There is a lack of a classification system providing uniformity in description and guiding management decisions for kyphotic spinal deformities. We developed such a classification based on column deficiency, flexibility of disc spaces, curve magnitude, and correlation with the corrective osteotomy required.

METHODS

A classification was developed based on analysis of 180 patients with thoracolumbar kyphosis requiring osteotomy. The deformity was classified as Type I if the anterior and posterior columns were intact (IA indicated mobile disc spaces and IB, ankylosed segments). Type II indicated deficiency of only 1 column (IIA = anterior column and IIB = posterior column). Type III indicated deficiency of both columns (IIIA = kyphosis of ≤60°, IIIB = kyphosis of >60°, and IIIC = buckling collapse). A prospective analysis of 76 patients was performed to determine interobserver variability and the ability of the classification to guide selection of osteotomies of increasing complexity, including the Ponte osteotomy, pedicle subtraction osteotomy, disc bone osteotomy, single vertebrectomy, multiple vertebrectomies, and anterior in situ strut fusion procedure.

RESULTS

The mean age of the 76 patients was 21.2 years, the mean kyphosis was 69.9° (range, 26° to 120°), and the mean follow-up duration was 30 months. Six deformities were classified as IA, 5 as IB, 5 as IIA, 2 as IIB, 13 as IIIA, 35 as IIIB, and 10 as IIIC. Four surgeons classifying the deformities had a high agreement rate (kappa = 0.83), with the highest agreement for Types IA, IB, and IIIB. A correlation between the type of deformity and the osteotomy performed demonstrated that the classification could indicate the type of osteotomy required. All 18 patients with Type-I or II kyphosis were treated with Ponte, pedicle subtraction, or disc bone osteotomy. Forty-three (90%) of the 48 patients with Type IIIA or IIIB underwent vertebrectomy (single in 27 [56%] and multiple in 16 [33%]), and only 5 (10%) underwent disc bone osteotomy. Seven of the 10 patients with Type-IIIC kyphosis were treated with multiple vertebrectomies, with 5 of them needing preoperative halo gravity traction; the other 3 patients underwent an anterior in situ strut fusion procedure.

CONCLUSIONS

The proposed classification based on the morphology of column deficiency, flexibility, and curve magnitude demonstrated a high interobserver agreement and ability to guide selection of the appropriate osteotomy.

CLINICAL RELEVANCE

A novel classification system for kyphosis based on spinal column deficiency, flexibility of disc spaces, and curve magnitude would bring uniformity in management and help guide surgeons in the choice of the appropriate corrective osteotomy.

Improved accuracy of screw implantation could decrease the incidence of post-operative hydrothorax? O-arm navigation vs. free-hand in thoracic spinal deformity correction surgery

PURPOSE

The purpose of this study was to analyze the occurrence of PE after intra-operative O-arm navigation-assisted surgery and determine whether the post-operative PE incidence could be decreased by using O-arm navigation as compared to conventional free-hand technique.

METHODS

A cohort of 27 patients with spinal deformity who were operated upon with an O-arm navigated system (group A) between 2013 and 2016 were enrolled in the study. A total of 27 curve-matched patients treated by conventional free-hand technique were included as the control group (group B). Whole spine posterior-anterior and lateral radiographs, and CT scans were taken pre and post-operation. Radiologic parameters and volume of PE were measured and compared between the two groups.

RESULTS

There were no significant differences in age, Cobb angle, and sagittal contour between the two groups pre-operatively. The mean total volume of post-operative PE was significantly larger in the free-hand group (p < 0.001). In the O-arm group, 59 malpositioned screws were identified in 22 patients. In the free-hand group, 88 malpositioned screws were found among 26 patients. The screw perforation rate was higher in the free-hand group than in the O-arm group (p = 0.007). In the O-arm group, the mean volume of PE was significantly larger among patients with malpositioned screws than those without malpositioned screws (p < 0.001), as well as in the free-hand group.

CONCLUSION

The volume of PE after correction surgery can be significantly decreased by application of O-arm navigation system as compared to conventional free-hand technique. We ascribed the improvement to the accuracy of screw implantation navigated by O-arm.

Adult Spinal Deformity: National Trends in the Presentation, Treatment, and Perioperative Outcomes From 2003 to 2010

STUDY DESIGN

Retrospective review of a prospective database.

OBJECTIVES

To investigate adult spinal deformity (ASD) surgery outcome trends on a nationwide scale using the Nationwide Inpatient Sample (NIS) from 2003 to 2010.

METHODS

ASD patients ≥25 years from 2003 to 2010 in the NIS undergoing anterior, posterior, or combined surgical approaches were included. Fractures, 9+ levels fused, or any cancer were excluded. Patient demographics, hospital data, and procedure-related complications were evaluated. Yearly trends were analyzed using univariate analysis and linear regression modeling.

RESULTS

Of 10,966 discharges, 1,952 were anterior, 6,524 were posterior, and 1,106 were combined. The total surgical ASD volume increased by 112.5% (p = .029), and both the average patient age (p < .001) and number of patients >65 years old significantly increased from 2003 to 2010 (p = .009). Anterior approach case volume decreased by 13.7% (p = .019), whereas that of combined increased by 22.7% (p = .047). Posterior case volume increased by 38.9% from 2003 to 2010, though insignificantly (p = .084). Total hospital charges for all approaches increased over the interval (p < .001). Total length of stay for all approaches decreased over the time interval (p < .005). Although the overall morbidity for all approaches increased by 22.7% (p < .001), mortality did not change (p = .817). The most common morbidities in 2003 were hemorrhagic anemia, accidental cut, puncture, perforation, or laceration during a procedure, and device-related complications, which persisted in 2010 with the exception of increased acute respiratory distress syndrome and pulmonary-related complications.

CONCLUSIONS

For ASD surgery from 2003 to 2010, the volume of anterior approaches decreased, whereas posterior procedures did not change, and combined approaches increased. Total hospital charges increased for all considered procedures, length of hospital stay decreased, whereas operative patients were increasingly elderly, and more procedures were observed for patients >65 years old. For all approaches, morbidity increased whereas mortality did not change. Future study is required to develop methods to reduce morbidity and costs, thereby optimizing patient outcomes.

Radiographic Predictors for Mechanical Failure After Adult Spinal Deformity Surgery: A Retrospective Cohort Study in 138 Patients

STUDY DESIGN

Retrospective cohort study at a single institution.

OBJECTIVE

We aimed at estimating the rate of revision procedures and identify radiographic predictors of mechanical failure after adult spinal deformity surgery.

SUMMARY OF BACKGROUND DATA

Mechanical failure rates after adult spinal deformity surgery range 12% to 37% in literature. Although the importance of spinal and spino-pelvic alignment is well documented for surgical outcome and ideal alignment has been proposed as sagittal vertical axis (SVA) < 5 cm, pelvic tilt < 20° and lumbar lordosis (LL) = pelvic incidence ± 9°, the role of radiographic sagittal spine parameters and alignment targets as predictors for mechanical failure remains uncertain.

METHODS

A consecutive cohort of adult spinal deformity patients who underwent corrective surgery with at least 5 levels of instrumentation between January 2008 and December 2012 at a single tertiary spine unit were followed for at least 2 years. Time to death or failure was recorded and cause-specific Cox regressions were applied to evaluate predictors for mechanical failure or death.

RESULTS

A total of 138 patients with median age of 61 years were included for analysis. Follow up ranged 2.1 to 6.8 years. In total 47% had revision and estimated failure rates were 16% at 1 year increasing to 56% at 5 years. A multivariate analysis adjusting for age at surgery showed increased hazard of failure from LL change > 30°, postoperative TK > 50°, and SS ≤30°. LL change was mostly because of 3-column osteotomy and ending the instrumentation at L5 or S1 increased the hazard of failure more than 6 fold compared with more cranial lumbar levels.

CONCLUSION

Mechanical failure rate was 47% after adult spinal deformity corrective surgery. LL change > 30°, postoperative TK > 50°, and postoperative SS ≤30° were independent radiographic predictors associated with increased hazard of failure.

LEVEL OF EVIDENCE

4.

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.

A Comprehensive Analysis of the SRS-Schwab Adult Spinal Deformity Classification and Confounding Variables: A Prospective, Non-US Cross-sectional Study in 292 Patients

STUDY DESIGN

Cross-sectional analyses on a consecutive, prospective cohort.

OBJECTIVE

To evaluate the ability of the Scoliosis Research Society (SRS)-Schwab Adult Spinal Deformity Classification to group patients by widely used health-related quality-of-life (HRQOL) scores and examine possible confounding variables.

SUMMARY OF BACKGROUND DATA

The SRS-Schwab Adult Spinal Deformity Classification includes sagittal modifiers considered important for HRQOL and the clinical impact of the classification has been validated in patients from the International Spine Study Group database; however, equivocal results were reported for the Pelvic Tilt modifier and potential confounding variables were not evaluated.

METHODS

Between March 2013 and May 2014, all adult spinal deformity patients from our outpatient clinic with sufficient radiographs were prospectively enrolled. Analyses of HRQOL variance and post hoc analyses were performed for each SRS-Schwab modifier. Age, history of spine surgery, and aetiology of spinal deformity were considered potential confounders and their influence on the association between SRS-Schwab modifiers and aggregated Oswestry Disability Index (ODI) scores was evaluated with multivariate proportional odds regressions. P values were adjusted for multiple testing.

RESULTS

Two hundred ninety-two of 460 eligible patients were included for analyses. The SRS-Schwab Classification significantly discriminated HRQOL scores between normal and abnormal sagittal modifier classifications. Individual grade comparisons showed equivocal results; however, Pelvic Tilt grade + versus +  + did not discriminate patients according to any HRQOL score. All modifiers showed significant proportional odds for worse aggregated ODI scores with increasing grade levels and the effects were robust to confounding. However, age group and aetiology had individual significant effects.

CONCLUSION

The SRS-Schwab sagittal modifiers reliably grouped patients graded 0 versus + / +  + according to the most widely used HRQOL scores and the effects of increasing grade level on odds for worse ODI scores remained significant after adjusting for potential confounders. However, effects of age group and aetiology should not be neglected.

LEVEL OF EVIDENCE

3.

Defining Spino-Pelvic Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for Age?

STUDY DESIGN

Retrospective review of prospective, multicenter database.

OBJECTIVE

The aim of the study was to determine age-specific spino-pelvic parameters, to extrapolate age-specific Oswestry Disability Index (ODI) values from published Short Form (SF)-36 Physical Component Score (PCS) data, and to propose age-specific realignment thresholds for adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

The Scoliosis Research Society-Schwab classification offers a framework for defining alignment in patients with ASD. Although age-specific changes in spinal alignment and patient-reported outcomes have been established in the literature, their relationship in the setting of ASD operative realignment has not been reported.

METHODS

ASD patients who received operative or nonoperative treatment were consecutively enrolled. Patients were stratified by age, consistent with published US-normative values (Norms) of the SF-36 PCS (<35, 35-44, 45-54, 55-64, 65-74, >75  y old). At baseline, relationships between between radiographic spino-pelvic parameters (lumbar-pelvic mismatch [PI-LL], pelvic tilt [PT], sagittal vertical axis [SVA], and T1 pelvic angle [TPA]), age, and PCS were established using linear regression analysis; normative PCS values were then used to establish age-specific targets. Correlation analysis with ODI and PCS was used to determine age-specific ideal alignment.

RESULTS

Baseline analysis included 773 patients (53.7 y old, 54% operative, 83% female). There was a strong correlation between ODI and PCS (r = 0.814, P < 0.001), allowing for the extrapolation of US-normative ODI by age group. Linear regression analysis (all with r > 0.510, P < 0.001) combined with US-normative PCS values demonstrated that ideal spino-pelvic values increased with age, ranging from PT = 10.9 degrees, PI-LL = -10.5 degrees, and SVA = 4.1 mm for patients under 35 years to PT = 28.5 degrees, PI-LL = 16.7 degrees, and SVA = 78.1 mm for patients over 75 years. Clinically, older patients had greater compensation, more degenerative loss of lordosis, and were more pitched forward.

CONCLUSION

This study demonstrated that sagittal spino-pelvic alignment varies with age. Thus, operative realignment targets should account for age, with younger patients requiring more rigorous alignment objectives.

Biomechanical analysis of Ponte and pedicle subtraction osteotomies for the surgical correction of kyphotic deformities

PURPOSE

Biomechanical analysis of Ponte (PO) and pedicle subtraction osteotomies (PSO) in kyphotic deformity instrumentation.

METHODS

Patient-specific biomechanical model was used to computationally simulate seven hyperkyphotic instrumentation cases with three osteotomy strategies-1-level PSO, 3-level PO, or 6-level PO; forces within the instrumented spine were assessed and results were analyzed through rANOVA tests.

RESULTS

Corrections with multi-level PO were close to those with one-level PSO. In upright position, average implant forces were from 225 to 280 N and rod bending moments were around 10 Nm with no significant difference between the three strategies (p < 0.05). In simulations of 30° flexion, rod bending moments increased by 38, 2, and 8 %, implant forces increased by 28, 23 and 26 % for the 1-level PSO, 3-level PO, and 6-level PO, respectively. Correction per vertebral level was smaller than the maximum correction allowed by PO and PSO.

CONCLUSIONS

Multi-level PO allows similar kyphotic correction to 1-level PSO in spinal deformities with mixed indications for PO and PSO. Loads on the instrumentation constructs in PSO were higher than multi-level PO and higher in 6-level PO than 3-level PO. High loads were located more on the osteotomy sites. The rod shape should be adapted to the anticipated spine correction on the osteotomy sites.

The reliability of sagittal pelvic parameters: the effect of lumbosacral instrumentation and measurement experience

STUDY DESIGN

Sagittal pelvic parameters (SPPs) of a representative patient sample drawn from a consecutive adult spinal deformity database were measured using Surgimap Spine. Estimated coefficient of reliability intraclass coefficient (95% confidence interval), standard error of measurement, and mean absolute deviation were used for the analysis.

OBJECTIVE

The primary objective of this study was to assess the reliability of SPP measurements using Surgimap Spine. The secondary objective was to evaluate the impact of pelvic instrumentation as well as the impact of user expertise.

SUMMARY OF BACKGROUND DATA

The radiographical measurement of SPP is increasingly recognized as playing a critical role in establishing the surgical goals and surgical strategy of many spinal disorders. Although instrumented flatback is a common cause of sagittal malalignment, to our knowledge, SPP measurement reliability has never been assessed in instrumented spines.

METHODS

Sixty-three adult full-spine standing lateral radiographs (31 with lumbosacral instrumentation) were measured twice by 13 observers using Surgimap Spine. Observers were stratified into 3 levels of experience: high (research coordinators, 4), mid (senior surgeons, 5), and low (junior surgeons, 4). Research coordinators trained all surgeons for less than 30 minutes. Parameters measured were pelvic incidence, pelvic tilt, and sacral slope.

RESULTS

Thirteen observers and 63 radiographs generated 817 observations (2 misses). Overall inter- and intraobserver reliability of SPP measurement was excellent (intraclass coefficient > 0.85). Lumbosacral instrumentation did not modify intraobserver reliability but reduced significantly interobserver reliability of pelvic tilt (P = 0.006) and sacral slope (P = 0.007). Experience did not affect intraobserver reliability but interobserver reliability of highly experienced observers was significantly lower (P < 0.05) than among less experienced observers.

CONCLUSION

Measurement of SPP using Surgimap Spine equals or improves previously reported reliability data. Lumbosacral instrumentation reduces interobserver reliability taking it from excellent to moderate in the sacral slope measurement. Inexperienced observers can measure SPP reliably after a short tutorial.

LEVEL OF EVIDENCE

4.