Pedicle Subtraction Osteotomy Research Articles

Predicting Complications in 153 Lumbar Pedicle Subtraction Osteotomies by a Single Surgeon Over a 6-Year Period.

Pedicle subtraction osteotomy (PSO) is a complex surgical procedure that provides correction of moderate sagittal imbalance. Surgical complications have adverse effects on patient outcomes and healthcare costs, making it imperative for clinical researchers to focus on minimizing complications. However, when it comes to risk modeling of PSO surgery, there is currently no consensus on which patient characteristics or measures should be used. This study aimed to describe complications and compare the performance of various sociodemographic characteristics, surgical variables, and established risk indices in predicting postoperative complications, infections, and readmissions after lumbar PSO surgeries. A review was conducted on 191 patients who underwent PSO surgery at a single institution by a single fellowship-trained orthopaedic spine surgeon between January 1, 2018, and December 31, 2021. Demographic, intraoperative, and postoperative data within 30 days, 1 year, and 2 years of the index procedure were evaluated. Descriptive statistics, t-test, chi-squared analysis, and logistic regression models were used. Intraoperative complications were significantly associated with coronary artery disease (odds ratios [OR] 3.95, P = 0.03) and operating room time (OR 1.01, P = 0.006). 30-day complications were significantly cardiovascular disease (OR 2.68, P = 0.04) and levels fused (OR 1.10, P = 0.04). 2-year complications were significantly associated with cardiovascular disease (OR 2.85, P = 0.02). 30-day readmissions were significantly associated with sex (4.47, 0.04) and length of hospital stay (χ2 = 0.07, P = 0.04). 2-year readmissions were significantly associated with age (χ2 = 0.50, P = 0.03), hypertension (χ2 = 4.64, P = 0.03), revision surgeries (χ2 = 5.46, P = 0.02), and length of hospital stay (χ2 = 0.07, P = 0.03). This study found that patients with coronary vascular disease and longer fusions were at higher risk of postoperative complications and patients with notable intraoperative blood loss were at higher risk of postoperative infections. In addition, physicians should closely follow patients with extended postoperative hospital stays, with advanced age, and undergoing revision surgery because these patients were more likely to be readmitted to the hospital.

Modified S1 Pedicle Subtraction Osteotomy.

Surgical technique video. To report a surgical technique to revise patients with previous fusions at L4-S1 leading to an iatrogenic flat back and sagittal imbalance using L5-S1 transforaminal interbody fusion combined with a small S1 corner osteotomy. This is a case of a woman (51 y old) with a history of multiple lumbar surgeries, severe back pain, sagittal imbalance, and loss of lordosis. We describe a feasible revision technique in a complex patient with the goal of attaining optimal distribution of lumbar lordosis and sagittal balance through a modified S1 pedicle subtraction osteotomy, and the use of an interbody cage to enhance the fusion rate and facilitate closure of the 3-column osteotomy. The preoperative patient lordosis angle of 31 degrees at L1-L4 and 16 degrees at L4-S1 became 12 degrees at L1-L4 and 44 degrees at L4-S1 postoperatively. The combination of L5-S1 transforaminal interbody fusion and S1 corner osteotomy is a feasible technique for the restoration of lumbar lordosis in patients with previous fusion and consequent loss of lordosis.

Current status of surgical treatment for angular kyphosis in spinal tuberculosis

To review current status of surgical treatment for angular kyphosis in spinal tuberculosis and provide reference for clinical treatment. The literature on the surgical treatment for angular kyphosis of spinal tuberculosis in recent years was extensively reviewed and summarized from the aspects of surgical indications, surgical contraindications, surgical approach, selection of osteotomy, and perioperative management. Angular kyphosis of spine is a common complication in patients with spinal tuberculosis. If kyphosis progresses gradually, it is easy to cause neurological damage, deterioration, and delayed paralysis, which requires surgical intervention. At present, surgical approaches for angular kyphosis of the spine include anterior approach, posterior approach, and combined anterior and posterior approaches. Anterior approach can be performed for patients with severe spinal cord compression and small kyphotic Cobb angle. Posterior approach can be used for patients with large kyphotic Cobb angle but not serious neurological impairment. A combined anterior and posterior approaches is an option for spinal canal decompression and orthosis. Osteotomy for kyphotic deformity include Smith-Peterson osteotomy (SPO), pedicle subtraction osteotomy (PSO), vertebral column resection(VCR), vertebral column decancellation (VCD), posterior vertebral column resection (PVCR), deformed complex vertebral osteotomy (DCVO), and Y-shaped osteotomy. SPO and PSO are osteotomy methods with relatively low surgical difficulty and low surgical risks, and can provide 15°-30° angular kyphosis correction effect. VCR or PVCR is a representative method of osteotomy and correction. The kyphosis correction can reach 50° and is suitable for patients with severe angular kyphosis. VCD, DCVO, and Y-shaped osteotomy are emerging surgical techniques in recent years. Compared with VCR, the surgical risks are lower and the treatment effects also improve to varying degrees. Postoperative recovery is also a very important part of the perioperative period and should be taken seriously. There is no consensus on the choice of surgical treatment for angular kyphosis in spinal tuberculosis. Osteotomy surgery are invasive, which is a problem that colleagues have always been concerned about. It is best to choose a surgical method with less trauma while ensuring the effectiveness.

Revision of Harrington rod constructs: a single-center's experience with this homogenous adult spinal deformity population at a minimum 2-year follow-up.

To evaluate radiographic and clinical outcomes following revision surgery after HRC fusions. Single-institution, retrospective study of patients revised following HRC with minimum 2-year follow-up post-revision. Demographics, perioperative information, radiographic parameters, complications, and Oswestry disability index (ODI) scores were collected. Radiographic parameters included global alignment, coronal and sagittal measurements pre and postoperatively, as well as final follow-up time points. 26 patients were included with a mean follow-up of 3.3 ± 1.1years. Mean age was 55.5 ± 7.8years, BMI 25.2 ± 5.8, and 22 (85%) were females. Instrumented levels increased from 9.7 ± 2.8 to 16.0 ± 2.2. Five (19.2%) patients underwent lumbar pedicle subtraction osteotomies, and 23 (88.4%) had interbody fusions. Patients significantly improved in all radiographic parameters at immediate and final follow-up (p < 0.005), except for thoracic kyphosis and pelvic incidence (p > 0.05). Correction was maintained from immediate postop to final follow-up (p > 0.05). 20 (76.9%) of patients experienced a complication at some point within the follow-up period with the most common being a lumbar nerve root deficit (n = 7). However, only one patient had a nerve root deficit at final follow-up, that being a 4/5 unilateral anterior tibialis function. 5 (19.2%) patients required further revision within a mean of 1.8 ± 1.1years. On average, patients had an improvement in ODI score by final follow-up (35.6 ± 16.8 vs 25.4 ± 19.8, p = 0.035). Patients revised for HRCs significantly improve, both clinically and radiographically by final follow-up. This group did have a propensity for distal lumbar root neurological issues, which were common but all patients except for one, recovered to full strength by two-year follow-up.

Pedicle subtraction osteotomy in patient with congenital kyphosis

IntroductionA disorder causes congenital kyphosis in the last stages of ossification and cartilage formation during embryonic development. The main treatment for this disease is surgery with various methods. The present study was performed to evaluate the results of the posterior surgery.MethodsThis study was a descriptive study comparing the results before and after surgery which was performed in 2022 on 14 patients with the congenital kyphosis referred to Al-Zahra Hospital in Isfahan. Initial assessments were performed, and the patient underwent surgery. The patients were re-evaluated immediately after surgery which were followed up and evaluated two years after surgery. Data were collected by a checklist and described and analyzed in SPSS software version 22.ResultsThe mean age of the patients was 23.15 ± 13.24 years, 7 patients (50%) were male, and the mean duration of surgery was 405.85 ± 123.99 min. Seven patients (50%) were under 18 years old. No disease died and the highest T12 involvement was in 5 patients (35.8%). Sagittal Vertical Axis, Kyphosis Angle and Lumbar Lordosis decreased in two stages immediately after surgery and follow-up, which were statistically significant (P < 0.05). No associated neurologic abnormalities was found during a physical examination or magnetic resonance imaging. In three phases (before, immediately after surgery, and follow-up), the mean of the Sagittal Vertical Axis, and Lumbar Lordosis in adults (over 18 years) and children (under 18 years) was not substantially different (P > 0.05). The mean Kyphosis Angle were significantly different in adults, and children at follow-up stages (P < 0.05). Because one of the children had a device filler in the follow-up stage.ConclusionsPSO can be used as a safe and effective technique to treat and correct Sagittal Vertical Axis, Kyphosis angle, Lumbar lordosis.

Complications and outcomes after three-column osteotomy: a 5-year follow-up

BACKGROUNDThree-column spinal osteotomies (3-CO) are powerful techniques used to correct spinal deformity. These surgeries are associated with an elevated risk of complications. While outcomes have been reported in the literature with 2 years follow-up, longer-term outcomes of three-column osteotomies remain understudied. OBJECTIVESThis study aims to examine patient reported outcomes and complications for three-column osteotomies at 5 years. STUDY DESIGNRetrospective review of a prospectively collected spinal deformity cases database. PATIENT SAMPLEAll consecutive adult patients at a single spine surgery center treated with either a pedicle subtraction osteotomy (PSO) or vertebral column resection (VCR) for spinal deformity, and with a minimum 5-year follow-up were included. OUTCOME MEASURESVisual-analog scale (VAS) for back pain score (0 to 10), Oswestry Disability Index (ODI) score (0 to 100), number of complications, revision rate, sagittal balance, lumbar lordosis at preoperative and at 5-year visit. METHODSData was extracted from a prospectively collected spinal deformity surgery database continuously updated since 2002 with data from operative reports, patients’ medical visit notes and patients’ self-reported VAS and ODI questionnaires completed at each office visit. Radiographic measurements were performed on standing full-length spine radiographs taken at pre-op and 5-year visits. Descriptive statistics, comparison of means and proportions among groups, and a logistic regression analysis were conducted using the statistical software package SPSS version 28. Statistical significance was set at p<.05. RESULTSOf 127 consecutive adult patients with minimum of 5-year follow-up undergoing a 3-CO posterior spinal surgery for spinal deformity were identified and included in the study, 79 (62%) were treated with PSO, and 48 (38%) with VCR. Both PSO and VCR groups demonstrated significant improvements in VAS (PSO pre-op: 6.7, 5-year: 4.6, p<.001; VCR pre-op: 7.1, 5-year: 5.2, p<.001), and ODI (PSO pre-op: 52.9, 5-year: 45.4, p<.001; VCR pre-op: 57.5, 5-year 43.0, p<.001) that were maintained at 5 years. Major and minor complications occurring within 5 years were not statistically different between the PSO and VCR groups (major: 59.5% vs 56.3%, p=.85; minor: 45.6% vs 37.5%, p=.46). The rate of revision surgery within 5 years was 39.4% overall. Of the fifty patients requiring revision, 37.5% were for nonunion, 27.1% instrumentation failure, 14.6% proximal junctional kyphosis (PJK), 12.5% vertebral fracture, 6.3% motor weakness, and 2.1% infection. Improvements in lumbar lordosis were maintained at 5 years in both the PSO (29.9° vs 47.2°, p<.001) and VCR (34.6° vs 48.5°, p<.001) groups while sagittal balance maintained significant improvement in the VCR group (9.5 cm vs 6.3 cm, p=.008) but not the PSO (11.4 cm vs 9.3 cm, p=.065). CONCLUSIONPatients undergoing three-column osteotomies had a major complication rate of 57.5% and a minor complication rate of 42.5% after 5 years. Improvements in lumbar lordosis were maintained at 5-year follow-up, but sagittal balance was only maintained in the VCR group. Despite these radiographic findings, both VCR and PSO groups maintained significant clinical improvements in both VAS and ODI scores at 5-year follow up.

Multiple three-column osteotomies successfully correcting cervicothoracic kyphosis in the setting of ankylosing spondylitis: illustrative case.

Ankylosing spondylitis (AS) is an autoimmune spondylarthritis often associated with rigid kyphoscoliosis. The authors describe a surgical approach that employs multilevel three-column osteotomies for the restoration of normal global alignment. A 48-year-old male with a past medical history of AS presented to the clinic with a stooped-over posture: his chin-brow vertical angle (CBVA) was 58.0°; T1 slope (T1S), 97.8°; thoracic kyphosis (TK; T1-12), 94.2°; proximal TK (T1-5), 50.8°; distal TK (T5-12), 43.5°; and sagittal vertical axis (SVA), 22.6 cm. A two-stage procedure was planned. During stage 1, instrumentation was placed from C5 to T10, followed by a T3 vertebral column resection. During stage 2, bilateral pedicle screws were placed from T11 to the pelvis. An L3 pedicle subtraction osteotomy (PSO) was completed and was followed by a T7 PSO. Postoperatively, the patient had significant postural improvement: CBVA was 29.3°; T1S, 57.8°; TK, 77.3°; proximal TK, 33.5°; distal TK, 43.8°; and SVA, 15 cm. At 6 years postoperatively, the patient continued to do well and was without evidence of construct breakdown. The authors propose that multilevel three-column osteotomies, if optimally located, successfully correct spinal malalignment associated with AS.

T1 Pedicle Subtraction Osteotomy With Subaxial Cervical Pedicle Screw Fixation.

Patients suffering from ankylosing spondylitis are not only predisposed to the development of rigid cervicothoracic deformities but are also at an increased risk of cervical fractures. Deformity correction and stabilization are particularly challenging in this patient population due to the brittle bone quality and low bone mineral density. Thoracic pedicle subtraction osteotomy is a workhorse approach for the correction of focal severe kyphotic deformity with lower complication rates than 3-column osteotomy. Successful execution of an upper thoracic PSO requires careful presurgical planning as well as anticipation of the patient's postoperative needs. Here, we describe the use of a T1 PSO in the correction of a rigid cervicothoracic chin-on-chest deformity in a patient with AS. The risk of implant failure was reduced by the use of a multi-rod construct, navigated cervical pedicle screws, and dual-pitched thoracic pedicle screws.

Finite element study on three osteotomy methods for treating thoracolumbar osteoporotic fracture vertebral collapse complicated with neurological dysfunction.

Surgical methods for patients with osteoporotic fracture vertebral collapse complicated with neurological dysfunction are still a topic of debate. We designed an improved osteotomy for the treatment of osteoporotic compression fracture patients with neurological dysfunction. Compared with traditional osteotomy methods such as pedicle subtraction osteotomy (PSO) and bone-disc-bone osteotomy (BDBO), the osteotomy range is reduced. Therefore, we use a finite element method to analyze the biomechanical conditions of these three osteotomy methods and provide a mechanical theoretical basis for the surgical treatment of these three osteotomy methods. Based on the CT scan of a patient with L1 osteoporotic fracture vertebral collapse and neurological dysfunction, the finite element model was constructed by importing Mimics software, and three different osteotomy models were established. The forces and displacements of internal fixation device, T1-L5 whole segment, T10 vertebral body, and T10/11 intervertebral disc were recorded under different working conditions. The displacement levels of internal fixation device, T1-L5 spine, T10 vertebral body, and T10/11 intervertebral disc in the modified osteotomy group were between BDBO group and PSO group. The stress in BDBO group was concentrated in titanium mesh and its maximum stress was much higher than that in PSO group and modified osteotomy group. The mechanical distribution of T10/11 intervertebral disc showed that the maximum stress distribution of the three osteotomy methods was similar. The relatively simple modified osteotomy has certain advantages in stress and displacement. In contrast, the stability of BDBO group was poor, especially in the lumbar intervertebral disc and lumbar body. For this type of osteotomy patients, it is recommended to avoid postoperative flexion so as not to increase the load.

Ideal length of accessory rod for the prevention of rod fracture after pedicle subtraction osteotomy in adult spinal deformity: short or long?

Pedicle subtraction osteotomy (PSO) is an effective surgical procedure for adult spinal deformity (ASD). However, the complexity of the procedure and its associated complications including rod fracture (RF) remain challenging issues. Among several RF reduction methods, the accessory rod (AR) is an important surgical technique. To date, knowledge about the ideal length and configuration of the AR is limited. This study aimed to assess the influence of the connection levels and configuration of the AR on RF occurrence in patients with ASD who underwent long level constructs and PSO. The authors retrospectively selected 57 consecutive patients (mean age 70.6 years) who underwent deformity correction including PSO and the AR technique with a minimum 2-year follow-up. The patients were classified into a non-RF group (n = 49) and an RF group (n = 8). Along with analysis of patient and radiological factors in the 2 groups, comparative studies were performed including configuration of the AR (D shaped vs linear shaped) and the connection levels of AR (long AR [the lower end below S1-2] vs short AR [above L5-S1]). The overall rate of RF incidence was 14% (8/57 cases) at an average of 42.5 months (2 patients with unilateral RF and 6 with bilateral RF). RF occurred most commonly at the L4-5 level, below the lower end of the AR: 6 below the lower end of the AR and 2 at the PSO site. There were no significant differences in patient and radiological factors between the groups. Comparisons between the 2 groups indicated that more RFs occurred when the configuration of the AR was a linear shape (p = 0.016) and when the distal end of the AR was above L5-S1 (p = 0.025). In this study the authors found that the D-shaped configuration of the AR and lower end of the AR below S1-2 (i.e., long AR) could be preventive methods for reducing RF after deformity correction performed using PSO and the AR technique for ASD. Here, the authors have provided the first comprehensive outline for the AR technique. These findings could establish effective guidelines for spine surgeons.

Multilevel Pedicle Subtraction Osteotomy for Correction of Thoracolumbar Kyphosis in Ankylosing Spondylitis: Clinical Effect and Biomechanical Evaluation.

To compare the clinical outcomes and biomechanical characteristics of 1-, 2-, and 3-level pedicle subtraction osteotomy (PSO), and establish selection criteria based on preoperative radiographic parameters. Patients undergone PSO to treat ankylosing spondylitis from February 2009 to May 2019 in Sun Yat-sen Memorial Hospital of Sun Yat-sen University were enrolled. According to the quantity of osteotomy performed, the participants were divided into group A (1-level PSO, n = 24), group B (2-level PSO, n = 19), and group C (3-level PSO, n = 11). Clinical outcomes were assessed before surgery and at the final follow-up. Comparisons of the radiographic parameters and quality-of-life indicators were performed among and within these groups, and the selection criteria were established by regression. Finite element analysis was conducted to compare the biomechanical characteristics of the spine treated with different quantity of osteotomies under different working conditions. Three-level PSO improved the sagittal parameters more significantly, but resulted in longer operative time and greater blood loss (p < 0.05). Greater stress was found in the proximal screws and proximal junction area of the vertebra in the model simulating 1-level PSO. Larger stress of screws and vertebra was observed at the distal end in the model simulating 3-level PSO. Multilevel PSO works better for larger deformity correction than single-level PSO by allowing greater sagittal parameter correction and obtaining a better distribution of stress in the hardware construct, although with longer operation time and greater blood loss. Three-level osteotomy is recommended for the patients with preoperative of global kyphosis > 85.95°, T1 pelvic angle > 62.3°, sagittal vertical alignment > 299.55 mm, and pelvic tilt+ chin-brow vertical angle > 109.6°.

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

BackgroundThe purpose of this study was to create a mathematical model to precalculate the acreage change in the abdominal median sagittal plane (ac-AMSP) of patients with ankylosing spondylitis (AS) for whom two-level pedicle subtraction osteotomy (PSO) was planned.MethodsA single-centre retrospective review of prospectively collected data was conducted among 11 adults with AS. Acreage of the abdominal median sagittal plane (a-AMSP) was performed. The distances and angles between the osteotomy apexes, anterosuperior edge of T12, xiphoid process, superior edge of the pubis, and anterosuperior corner of the sacrum were measured on preoperative thoracolumbar computed tomography. A mathematical model was created using basic trigonometric functions in accordance with the abdominal parameters. Planned osteotomized vertebra angles (POVAs) were substituted into the mathematical model, and the predictive ac-AMSP (P-AC) was obtained. A paired sample t test was performed to determine the differences between the P-AC and actual ac-AMSP (A-AC) and between the predictive acreage change rate (P-CR) and actual acreage change rate (A-CR).ResultsThe mean age and GK were 44.4 ± 8.99 years and 102.9° ± 19.17°, respectively. No significant difference exists between A-CR and P-CR via mathematical modeling (p > 0.05). No statistically significant difference existed between POVA and actual osteotomized vertebra angles (AOVA) (p > 0.05). A statistically significant difference was observed between preoperative and postoperative measurements of LL, SVA, and GK variables (p < 0.001).ConclusionsThe novel mathematical model was reliable in predicting the ac-AMSP in AS patients undergoing two-level PSO.

Effects of Minimally Invasive Lateral Lumbar Interbody Fusion with Accessory Rod Technique on Rod Fracture in Adult Spinal Deformity Surgery: Analysis of 239 Patients.

A retrospective study. To analyze factors associated with rod fracture (RF) in adult spinal deformity (ASD), and to assess whether the accessory rod (AR) technique can reduce RF occurrence in deformity correction in the setting of minimally invasive lateral lumbar interbody fusion (LLIF). Instrumentation failure is the most common reason for revision surgery in ASD. Several RF reduction methods have been introduced. However, there are insufficient studies on postoperative RF after deformity correction using minimally invasive LLIF. This study included 239 patients (average age 71.4y and a minimum 2-year follow up) with ASD who underwent long-segment fusion from T10 to sacrum with sacropelvic fixation. Patients were classified into the non-RF group and the RF group. After logistic regression analysis of the risk factors for RF, subgroup analyses were performed; pedicle subtraction osteotomy (PSO) with 2-rod (P2 group) versus PSO with 2-rod and AR (P4 group), and LLIF with 2-rod (L2 group) versus LLIF with 2-rod and AR (L4 group). RF occurred in 50 patients (21%) at an average of 25 months. RF occurred more frequently in patients who underwent PSO than in those who underwent LLIF (P=0.002), and the use of the AR technique was significantly higher in the non-RF group (P<0.05).Following logistic regression analysis, preoperative PI-LL mismatch, PSO, and the AR technique were associated with RF. In subgroup analyses, RF incidence was 65% (24/37 cases) of P2 group, 8% (4/51 cases) of P4 group, and 21% (22/105 cases) of L2 group. In the L4 group, there was no RF. Minimally invasive multilevel LLIF with the AR technique is capable of as much LL correction as conventional PSO and appears to be an effective method for reducing RF.

The Predictors of Incidental Durotomy in Patients Undergoing Pedicle Subtraction Osteotomy for the Correction of Adult Spinal Deformity.

Background: Pedicle subtraction osteotomy (PSO) is a powerful tool for sagittal plane correction in patients with rigid adult spinal deformity (ASD); however, it is associated with high intraoperative blood loss and the increased risk of durotomy. The objective of the present study was to identify intraoperative techniques and baseline patient factors capable of predicting intraoperative durotomy. Methods: A tri-institutional database was retrospectively queried for all patients who underwent PSO for ASD. Data on baseline comorbidities, surgical history, surgeon characteristics and intraoperative maneuvers were gathered. PSO aggressiveness was defined as conventional (Schwab 3 PSO) or an extended PSO (Schwab type 4). The primary outcome of the study was the occurrence of durotomy intraoperatively. Univariable analyses were performed with Mann-Whitney U tests, Chi-squared analyses, and Fisher's exact tests. Statistical significance was defined by p < 0.05. Results: One hundred and sixteen patients were identified (mean age 61.9 ± 12.6 yr; 44.8% male), of whom 51 (44.0%) experienced intraoperative durotomy. There were no significant differences in baseline comorbidities between those who did and did not experience durotomy, with the exception that baseline weight and body mass index were higher in patients who did not suffer durotomy. Prior surgery (OR 2.73; 95% CI [1.13, 6.58]; p = 0.03) and, more specifically, prior decompression at the PSO level (OR 4.23; 95% CI [1.92, 9.34]; p < 0.001) was predictive of durotomy. A comparison of surgeon training showed no statistically significant difference in durotomy rate between fellowship and non-fellowship trained surgeons, or between orthopedic surgeons and neurosurgeons. The PSO level, PSO aggressiveness, the presence of stenosis at the PSO level, nor the surgical instrument used predicted the odds of durotomy occurrence. Those experiencing durotomy had similar hospitalization durations, rates of reoperation and rates of nonroutine discharge. Conclusions: In this large multisite series, a history of prior decompression at the PSO level was associated with a four-fold increase in intraoperative durotomy risk. Notably the use of extended (versus) standard PSO, surgical technique, nor baseline patient characteristics predicted durotomy. Durotomies occurred in 44% of patients and may prolong operative times. Additional prospective investigations are merited.

The Advantages of 4-rod Construct over the 2-rod Techniques in Adult Spinal Deformity Patients who Underwent Pedicle Subtraction Osteotomy: A Multicenter Retrospective Comparative Study

Study DesignRetrospective study ObjectiveTo compare clinicoradiological outcomes and complication profiles of the traditional two-rod construct versus the four-rod construct in patients with adult spinal deformity (ASD) who underwent pedicle subtraction osteotomy (PSO). MethodsWe performed a retrospective review of 208 ASD patients who underwent lumbar PSO and long fusion from thoracic to the pelvis at two centers. Two different techniques including the four-rod construct and the traditional two-rod technique were used at the PSO level. Clinicoradiological outcomes and complication profiles of the patients were documented and compared statistically between the groups. ResultsThe four-rod construct was associated with statistically lower rates of rod fracture (44.8% vs 26.4%, p<0.01), pedicular screw loosening at the PSO level (25.3% vs 14.0%, p=0.04) and reoperation (49.4% vs 33.9%, p=0.02). Radiologically, the four-rod technique was associated with higher degree of lumbar lordosis (LL) (-37.4°vs -26.8°; p<0.01) and improved pelvic tilt (PT) (-17.2° vs -9.9°; p<0.01) and sacral vertical axis (SVA) corrections (-211.5° vs -192.2°; p=0.04). Overall, the four-rod construct was associated with improved quality of life (p=0.04) and statistically lower oswestry disability index at 12 months postoperatively (p<0.01). ConclusionsOur results showed that the four-rod construct was associated with statistically lower rates of rod fracture and pedicular screw loosening at the osteotomy level, higher degree of LL correction and improved PT and SVA than the two-rod technique. The four-rod technique was also associated with improved quality of life and disability index and lower complication profiles.

Pedicle Subtraction Osteotomy Versus Multilevel Anterior Lumbar Interbody Fusion and Lateral Lumbar Interbody Fusion in the Treatment of Adult Spinal Deformity: Trends, Outcomes, and Cost.

Retrospective cohort study. The aim of this study was to compare the outcomes of pedicle subtraction osteotomy (PSO) with multilevel anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) in posterior long-segment fusion. PSO and ALIF/LLIF are 2 techniques used to restore lumbar lordosis and correct sagittal alignment, with each holding its unique advantages and disadvantages. As there are situations where both techniques can be employed, it is important to compare the risks and benefits of both. Patients aged 18 years or older who underwent PSO or multilevel ALIF/LLIF with posterior fusion of 7-12 levels and pelvic fixation were identified. 1:1 propensity score was used to match PSO and ALIF/LLIF cohorts for age, sex, and relevant comorbidities, including smoking status. Logistic regression was used to compare medical and surgical outcomes. Trends and costs were generated for both groups as well. ALIF/LLIF utilization in posterior long fusion has been steadily increasing since 2010, whereas PSO utilization has significantly dropped since 2017. PSO was associated with an increased risk of durotomy (P < 0.001) and neurological injury (P = 0.018). ALIF/LLIF was associated with increased rates of postoperative radiculopathy (P = 0.005). Patients who underwent PSO had higher rates of pseudarthrosis within 1 and 2 years (P = 0.015; P = 0.010), 1-year hardware failure (P = 0.028), and 2-year reinsertion of instrumentation (P = 0.009). Reoperation rates for both approaches were not statistically different at any time point throughout the 5-year period. In addition, there were no significant differences in both procedural and 90-day postoperative costs. PSO was associated with higher rates of surgical complications compared with anterior approaches. However, there was no significant difference in overall reoperation rates. Spine surgeons should select the optimal technique for a given patient and the type of lordotic correction required.

The "Sandwich" Extended Pedicle Subtraction Osteotomy for the Treatment of Fixed Sagittal Malalignment: Technical Description, Case Series, and Early Results With 2-Year Outcomes.

Adult spinal deformity (ASD) with fixed sagittal malalignment (FSM) may require a pedicle subtraction osteotomy (PSO) for greater focal lordosis and restoration of global alignment. Despite growing trends in minimizing PSOs given their associated high risks, a considerable portion of patients with ASD still require a lumbar PSO most commonly because of iatrogenic flat back deformity. The purpose of this article is to describe a modified extended PSO technique with additional anterior column support coined the "sandwich" extended PSO (SE-PSO) to promote arthrodesis and report the outcomes in a consecutive case series. Patients with ASD treated with a lumbar SE-PSO at a single institution from 2015 to 2020 were analyzed. Complications, radiographic data, and patient-reported outcomes were compared preoperatively, at immediate postoperative follow-up, and at a 2-year postoperative follow-up (FU). Fourteen patients who underwent revision operations for FSM were included. Improvements in segmental lordosis across the PSO site (14.8 ± 6.8 vs 39.9 ± 7.1, P < .0001), overall lumbar lordosis (14.6 ± 15.4 vs 44.6 ± 12.1, P < .0001), sacral slope (21.0 ± 10.5 31.1 ± 10.7, P = .0150), C7 sagittal vertical axis (140.1 ± 59.0 mm vs 35.9 ± 28.5, P < .0001), and spinopelvic mismatch (52.5 ± 21.3 vs 18.6 ± 14.1, P = .0001) were obtained in all patients. Eight patients experienced perioperative complications, with intraoperative durotomy being the most common (n = 7). Eight patients had a 2-year FU and demonstrated improvements in their segmental lordosis across the PSO site (14.3 ± 7.0 vs 41.3 ± 7.3, P = .0003), overall lumbar lordosis (8.7 ± 17.8 vs 46.1 ± 14.2, P = .0014), sacral slope (19.1 ± 12.8 vs 32.3 ± 12.5, P = .0479), C7 sagittal vertical axis (173.6 ± 54.4 mm vs 35.8 ± 30.0, P < .0001), and spinopelvic mismatch (63.0 ± 19.7 vs 21.1 ± 18.3, P < .0001), all of which were maintained at final FU (P > .05). At 2 years, a significant increase in Scoliosis Research Society-22r total score (2.5 ± 0.8 vs 3.6 ± 0.7, P = .0023 was reported. There were no reports of symptomatic pseudarthrosis or mechanical complications. SE-PSO is an effective technique to correct FSM and is associated with low complications, improved patient-reported outcomes, and spinopelvic parameters that are maintained at 2 years.

Postoperative quality of life in patients with ankylosing spondylitis and thoracolumbar kyphosis: risk factors and personalized sagittal reconstruction strategy.

The aim of this study was to investigate the factors affecting postoperative quality of life in patients with ankylosing spondylitis (AS) and thoracolumbar kyphosis (TLK), and establish a personalized sagittal reconstruction strategy. Patients with AS and TLK who underwent pedicle subtraction osteotomy (PSO) from February 2009 to May 2019 were retrospectively included. Quality of life and spinal sagittal radiographic parameters were collected before surgery and at the last follow-up. Patients were divided into two groups based on the attainment of minimal clinically important difference (MCID) on the Bath Ankylosing Spondylitis Functional Index and Oswestry Disability Index. Comparisons of radiographic parameters and clinical outcomes were conducted between and within groups. Regression analysis was used to identify the risk factors within the missing MCID cohort. Sagittal reconstruction equations were established using the pelvic incidence (PI) and thoracic inlet angle (TIA) in the reached MCID cohort. The study comprised 82 participants. Significant improvements were observed in most radiographic parameters and all quality-of-life indicators during the final follow-up compared with the preoperative measures (p < 0.05). Factors including cervical lordosis (CL) ≥ 18° (OR 9.75, 95% CI 2.26-58.01, p = 0.005), chin-brow vertical angle (CBVA) ≥ 25° (OR 14.7, 95% CI 3.29-91.21, p = 0.001), and pelvic tilt (PT) ≥ 33° (OR 21.77, 95% CI 5.92-103.44, p < 0.001) independently correlated with a failure to attain MCID (p < 0.05). Sagittal realignment targets were constructed as follows: sacral slope (SS) = 0.84 PI - 17.4° (R2 = 0.81, p < 0.001), thoracic kyphosis (TK) = 0.51 PI + 10.8° (R2 = 0.46, p = 0.002), neck tilt (NT) = 0.52 TIA - 5.8° (R2 = 0.49, p < 0.001), and T1 slope (T1S) = 0.48 TIA + 5.8° (R2 = 0.45, p = 0.002). PSO proved efficacious in treating AS complicated by TLK, yielding favorable outcomes. CBVA ≥ 25°, CL ≥ 18°, and PT ≥ 33° were the primary factors affecting postoperative quality of life in patients with AS. The personalized sagittal reconstruction strategy in this study focused on the subjective sensations and daily needs of patients with AS, which were delineated by the equations SS = 0.84 PI - 17.4°, TK = 0.51 PI + 10.8°, NT = 0.52 TIA - 5.8°, and T1S = 0.48 TIA + 5.8°.

Biomechanical evaluation of multi-rod constructs to stabilize an S1 pedicle subtraction osteotomy (PSO): a finite element analysis.

To develop and validate a finite element (FE) model of a sacral pedicle subtraction osteotomy (S1-PSO) and to compare biomechanical properties of various multi-rod configurations to stabilize S1-PSOs. A previously validated FE spinopelvic model was used to develop a 30° PSO at the sacrum. Five multi-rod techniques spanning the S1-PSO were made using 4 iliac screws and a variety of primary rods (PR) and accessory rods (AR; lateral: Lat-AR or medial: Med-AR). All constructs, except one, utilized a horizontal rod (HR) connecting the iliac bolts to which PRs and Med-ARs were connected. Lat-ARs were connected to proximal iliac bolts. The simulation was performed in two steps with the acetabula fixed. For each model, PSO ROM and maximum stress on the PRs, ARs, and HRs were recorded and compared. The maximum stress on the L5-S1 disc and the PSO forces were captured and compared. Highest PSO ROMs were observed for 4-Rods (HR + 2 Med-AR). Constructs consisting of 5-Rods (HR + 2 Lat-ARs + 1 Med-AR) and 6-Rods (HR + 2 Lat-AR + 2 Med-AR) had the lowest PSO ROM. The least stress on the primary rods was seen with 6-Rods, followed by 5-Rods and 4-Rods (HR + 2 Lat-ARs). Lowest PSO forces and lowest L5-S1 disc stresses were observed for 4-Rod (Lat-AR), 5-Rod, and 6-Rod constructs, while 4-Rods (HR + Med-AR) had the highest. In this first FE analysis of an S1-PSO, the 4-Rod construct (HR + Med-AR) created the least rigid environment and highest PSO forces anteriorly. While 5- and 6-Rods created the stiffest constructs and lowest stresses on the primary rods, it also jeopardized load transfer to the anterior column, which may not be favorable for healing anteriorly. A balance between the construct's rigidity and anterior load sharing is essential.

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 importanceA 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 presentationThis 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 discussionA 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. ConclusionCombined 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.