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Risk factors for sacral fracture following en bloc chordoma resection

Anthony L. Mikula, Zach Pennington, Nikita Lakomkin, Marc Prablek, Behrang Amini, S. Mohammed Karim, Shalin S. Patel, Daniel Lubelski, Daniel M. Sciubba, Christopher Alvarez-Breckenridge, Robert Y. North, Claudio E. Tatsui, Mohamad Bydon, Jeremy L. Fogelson, Benjamin D. Elder, William E. Krauss, Justin E. Bird, Peter S. Rose, Michelle J. Clarke, and Laurence D. Rhines

OBJECTIVE

The purpose of this study was to analyze risk factors for sacral fracture following noninstrumented partial sacral amputation for en bloc chordoma resection.

METHODS

A multicenter retrospective chart review identified patients who underwent noninstrumented partial sacral amputation for en bloc chordoma resection with pre- and postoperative imaging. Hounsfield units (HU) were measured in the S1 level. Sacral amputation level nomenclature was based on the highest sacral level with bone removed (e.g., S1 foramen amputation at the S1–2 vestigial disc is an S2 sacral amputation). Variables collected included basic demographics, patient comorbidities, surgical approach, preoperative radiographic details, neoadjuvant and adjuvant radiation therapy, and postoperative sacral fracture data.

RESULTS

A total of 101 patients (60 men, 41 women) were included; they had an average age of 69 years, BMI of 29 kg/m2, and follow-up of 60 months. The sacral amputation level was S1 (2%), S2 (37%), S3 (44%), S4 (9%), and S5 (9%). Patients had a posterior-only approach (77%) or a combined anterior–posterior approach (23%), with 10 patients (10%) having partial sacroiliac (SI) joint resection. Twenty-seven patients (27%) suffered a postoperative sacral fracture, all occurring between 1 and 7 months after the index surgery. Multivariable logistic regression analysis demonstrated S1 or S2 sacral amputation level (p = 0.001), combined anterior–posterior approach (p = 0.0064), and low superior S1 HU (p = 0.027) to be independent predictors of sacral fracture. The fracture rate for patients with superior S1 HU < 225, 225–300, and > 300 was 38%, 15%, and 9%, respectively. An optimal superior S1 HU cutoff of 300 was found to maximize sensitivity (89%) and specificity (42%) in predicting postamputation sacral fracture. In addition, the fracture rate for patients who underwent partial SI joint resection was 100%.

CONCLUSIONS

Patients with S1 or S2 partial sacral amputations, a combined anterior–posterior surgical approach, low superior S1 HU, and partial SI joint resection are at higher risk for postoperative sacral fracture following en bloc chordoma resection and should be considered for spinopelvic instrumentation at the index procedure.

In Journal of Neurosurgery: Spine Publish Before Print

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The association between Disease Activity Score and rheumatoid arthritis–associated cervical deformity: radiological evaluation of the BeSt trial

Anna B. Lebouille-Veldman, Dylan Spenkelink, Cornelia F. Allaart, and Carmen L. A. Vleggeert-Lankamp

OBJECTIVE

The authors’ objective was to evaluate the association of the Disease Activity Score (DAS) with cervical spine deformity in rheumatoid arthritis (RA) patients during 10-year optimal treatment of systemic disease.

METHODS

The authors evaluated radiological and 10-year follow-up (FU) data of the BeSt (BehandelStrategien) trial. In 272 RA patients, atlantoaxial subluxation (AAS), presence of vertical translocation (VT), and subaxial subluxation (SAS) were evaluated. The associations of these deformities with DAS, self-assessed health (determined with the Health Assessment Questionnaire [HAQ]), and erosions of the hands and feet (Sharp–Van der Heijde score) were studied.

RESULTS

After 10 years of FU, AAS (> 2 mm neutral position) was observed in 62 patients (23%), AAS (≥ 3 mm in flexion) in 24%, AAS (≥ 5 mm in flexion) in 7%, VT did not occur, and SAS was present in 60 patients (22%). In total, 135 patients (50%) were in remission (DAS < 1.6) at 10 years of FU. No association could be established between AAS and DAS. Patients with cervical spine deformity (AAS > 2 mm and/or SAS) at 10 years had a higher HAQ score at 10 years than patients without cervical spine deformity (HAQ scores of 0.65 and 0.51, respectively, p = 0.04; 95% CI –0.29 to 0.00).

CONCLUSIONS

Even though 50% of patients were in remission after 10 years and the BeSt trial was designed to optimize treatment, 40% of patients developed at least mild RA-associated cervical spine deformity and 7% developed significant AAS. This indicates that even in this era of disease-modifying antirheumatic drugs and biologicals, cervical deformity is prevalent among patients with RA and should not be neglected in patient treatment plans and information.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Predictors of spinal trauma care and outcomes in a resource-constrained environment: a decision tree analysis of spinal trauma surgery and outcomes in Tanzania

Andreas Leidinger, Scott L. Zuckerman, Yueqi Feng, Yitian He, Xinrui Chen, Beverly Cheserem, Linda M. Gerber, Noah L. Lessing, Hamisi K. Shabani, Roger Härtl, and Halinder S. Mangat

OBJECTIVE

The burden of spinal trauma in low- and middle-income countries (LMICs) is immense, and its management is made complex in such resource-restricted settings. Algorithmic evidence-based management is cost-prohibitive, especially with respect to spinal implants, while perioperative care is work-intensive, making overall care dependent on multiple constraints. The objective of this study was to identify determinants of decision-making for surgical intervention, improvement in function, and in-hospital mortality among patients experiencing acute spinal trauma in resource-constrained settings.

METHODS

This study was a retrospective analysis of prospectively collected data in a cohort of patients with spinal trauma admitted to a tertiary referral hospital center in Dar es Salam, Tanzania. Data on demographic, clinical, and treatment characteristics were collected as part of a quality improvement neurotrauma registry. Outcome measures were surgical intervention, American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade improvement, and in-hospital mortality, based on existing treatment protocols. Univariate analyses of demographic and clinical characteristics were performed for each outcome of interest. Using the variables associated with each outcome, a machine learning algorithm-based regression nonparametric decision tree model utilizing a bootstrapping method was created and the accuracy of the three models was estimated.

RESULTS

Two hundred eighty-four consecutively admitted patients with acute spinal trauma were included over a period of 33 months. The median age was 34 (IQR 26–43) years, 83.8% were male, and 50.7% had experienced injury in a motor vehicle accident. The median time to hospital admission after injury was 2 (IQR 1–6) days; surgery was performed after a further median delay of 22 (IQR 13–39) days. Cervical spine injury comprised 38.4% of the injuries. Admission AIS grades were A in 48.9%, B in 16.2%, C in 8.5%, D in 9.5%, and E in 16.6%. Nearly half (45.1%) of the patients underwent surgery, 12% had at least one functional improvement in AIS grade, and 11.6% died in the hospital. Determinants of surgical intervention were age ≤ 30 years, spinal injury level, admission AIS grade, delay in arrival to the referral hospital, undergoing MRI, and type of insurance; admission AIS grade, delay to arrival to the hospital, and injury level for functional improvement; and delay to arrival, injury level, delay to surgery, and admission AIS grade for in-hospital mortality. The best accuracies for the decision tree models were 0.62, 0.34, and 0.93 for surgery, AIS grade improvement, and in-hospital mortality, respectively.

CONCLUSIONS

Operative intervention and functional improvement after acute spinal trauma in this tertiary referral hospital in an LMIC environment were low and inconsistent, which suggests that nonclinical factors exist within complex resource-driven decision-making frameworks. These nonclinical factors are highlighted by the authors’ results showing clinical outcomes and in-hospital mortality were determined by natural history, as evidenced by the highest accuracy of the model predicting in-hospital mortality.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Alternatives to DEXA for the assessment of bone density: a systematic review of the literature and future recommendations

Nachiket Deshpande, Moustafa S. Hadi, Jock C. Lillard, Peter G. Passias, Joseph R. Linzey, Yamaan S. Saadeh, Michael LaBagnara, and Paul Park

OBJECTIVE

Osteoporosis has significant implications in spine fusion surgery, for which reduced spinal bone mineral density (BMD) can result in complications and poorer outcomes. Currently, dual-energy x-ray absorptiometry (DEXA) is the gold standard for radiographic diagnosis of osteoporosis, although DEXA accuracy may be limited by the presence of degenerative spinal pathology. In recent years, there has been an evolving interest in using alternative imaging, including CT and MRI, to assess BMD. In this systematic review of the literature, the authors assessed the use and effectiveness of MRI, opportunistic CT (oCT), and quantitative CT (qCT) to measure BMD.

METHODS

In accordance with the PRISMA guidelines, the authors conducted a systematic search for articles posted on PubMed between the years 2000 and 2022 by using the keywords "opportunistic CT, quantitative CT, MRI" AND "bone density" AND "spine." Inclusion criteria consisted of articles written in English that reported studies pertaining to human or cadaveric subjects, and studies including a measure of spinal BMD. Articles not related to spinal BMD, osteoporosis, or spinal surgery or reports of studies that did not include the use of spinal MRI or CT were excluded. Key study outcomes were extracted from included articles, and qualitative analysis was subsequently performed.

RESULTS

The literature search yielded 302 articles. Forty-two articles reported studies that met the final inclusion criteria. Eighteen studies utilized MRI protocols to correlate spinal BMD with vertebral bone quality scores, M-scores, and quantitative perfusion markers. Eight studies correlated oCT with spinal BMD, and 16 studies correlated qCT with spinal BMD. With oCT and qCT imaging, there was consensus that Hounsfield unit (HU) values > 160 demonstrated significant reduction in risk of osteoporosis, whereas HU values < 110 were significantly correlated with osteoporosis.

CONCLUSIONS

Osteoporosis is increasingly recognized as a significant risk factor for complications after spinal fusion surgery. Consequently, preoperative assessment of BMD is a critical factor to consider in planning surgical treatment. Although DEXA has been the gold standard for BMD measurement, other imaging modalities, including MRI, oCT, and qCT, appear to be viable alternatives and may offer cost and time savings.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Cervicothoracic junction instrumentation strategies following separation surgery for spinal metastases

Vikram B. Chakravarthy, Ibrahim Hussain, Ilya Laufer, Jacob L. Goldberg, Anne S. Reiner, Jemma Villavieja, William Christopher Newman, Ori Barzilai, and Mark Bilsky

OBJECTIVE

The cervicothoracic junction (CTJ) is a challenging region to stabilize after tumor resection for metastatic spine disease. The objective of this study was to describe the outcomes of patients who underwent posterolateral decompression and instrumented fusion (i.e., separation surgery across the CTJ for instability due to metastatic disease).

METHODS

The authors performed a single-institution retrospective study of a prospectively collected cohort of patients who underwent single-approach posterior decompression and instrumented fusion across the CTJ for metastatic spine disease between 2011 and 2018. Adult patients (≥ 18 years old) who presented with mechanical instability, myelopathy, and radiculopathy secondary to metastatic epidural spinal cord compression (MESCC) of the CTJ (C7–T1) from 2011 to 2018 were included.

RESULTS

Seventy-nine patients were included, with a mean age of 62.1 years. The most common primary malignancies were non–small cell lung (n = 17), renal cell (11), and prostate (8) carcinoma. The median number of levels decompressed and construct length were 3 and 7, respectively. The average operative time, blood loss, and length of stay were 179.2 minutes, 600.5 ml, and 7.7 days, respectively. Overall, 58 patients received adjuvant radiation, and median dose, fractions, and time from surgery were 27 Gy, 3 fractions, and 20 days, respectively. All patients underwent lateral mass and pedicle screw instrumentation. Forty-nine patients had tapered rods (4.0/5.5 mm or 3.5/5.5 mm), 29 had fixed-diameter rods (3.5 mm or 4.0 mm), and 1 had both. Ten patients required anterior reconstruction with poly-methyl-methacrylate. The overall complication rate was 18.8% (6 patients with wound-related complications, 7 with hardware-related complications, 1 with both, and 1 with other). For the 8 patients (10%) with hardware failure, 7 had tapered rods, all 8 had cervical screw pullout, and 1 patient also experienced rod/screw fracture. The average time to hardware failure was 146.8 days. The 2-year cumulative incidence rate of hardware failure was 11.1% (95% CI 3.7%–18.5%). There were 55 deceased patients, and the median (95% CI) overall survival period was 7.97 (5.79–12.60) months. For survivors, the median (range) follow-up was 12.94 (1.94–71.80) months.

CONCLUSIONS

Instrumented fusion across the CTJ demonstrated an 18.8% rate of postoperative complications and an 11% overall 2-year rate of hardware failure in patients who underwent metastatic epidural tumor decompression and stabilization.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Defining postoperative C5 palsy and recovery: a systematic review

Nachiket Deshpande, Amro M. Stino, Brandon W. Smith, Ann A. Little, Lynda J. S. Yang, Paul Park, and Yamaan S. Saadeh

OBJECTIVE

Postoperative C5 palsy (C5P) is a well-recognized and often-delayed complication of cervical spine surgery. Most patients recover within 6 months of onset, but the prognosis of severe cases is poor. The clinical significance and natural history of mild versus severe C5P appear to differ substantially, but palsy severity and recovery have been poorly characterized in the literature.

METHODS

Owing to the varying prognoses and expanding treatment options such as nerve transfer surgery to reconstruct the C5 myotome, this systematic review attempted to describe how C5P severity is classified and how C5P and its recovery are defined, with the aim of proposing a postoperative C5P scale to support clinical decision-making. PubMed was searched for articles in English published since 2000 that offer a clear definition of postoperative C5P or its recovery. Only articles reporting exclusively on C5 palsy for patients undergoing surgery for degenerative disease were included. A single reviewer screened titles and abstracts and reviewed the full text of relevant articles, with consultation as needed from a second reviewer. Data collected included postoperative C5P definitions, classification of C5P severity, and definition and/or classification of C5P recovery. Qualitative analysis was performed.

RESULTS

Full-text reviews were conducted of 98 of 272 articles identified and screened, and 43 met the inclusion criteria. Postoperative C5P was most commonly defined as a reduction in deltoid muscle strength by ≥ 1 grade using manual muscle testing (MMT), with potential biceps involvement also noted by some studies. The few studies that stratified C5P on the basis of severity unanimously characterized severe C5P as MMT grade ≤ 2. Nine studies reported on C5P recovery. Deltoid muscle strength improvement of MMT grade 5 commonly defined complete recovery, with no MMT improvement considered partial recovery.

CONCLUSIONS

This review identified clear discrepancies in the definitions of C5P and its recovery, leading to heterogeneity in its evaluation and management. With the emergence of therapeutic procedures for severe C5P, standardization of the definitions of C5P and its recovery is critical. The authors propose MMT grades of 4, 3, and ≤ 2 to classify C5P as mild, moderate, and severe, respectively, and grades of 5, 4, and 3 to classify recovery as complete, sufficient, and useful, respectively.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Implementation of a spine triage program and its effect on outpatient radiology utilization

Emma N. Ryan, Yagiz Yolcu, Tasneem Z. Rizvi, Susan R. Christopher, Melissa R. Dunbar, Robert G. Whitmore, and Zoher Ghogawala

OBJECTIVE

Clinical care pathways designed to triage spinal disorders have been shown to reduce wait times and improve patient satisfaction. The goal of this study was to perform an analysis of outpatient radiology costs before and after the implementation of a spine care triage pathway.

METHODS

All imaging orders and surgical procedures were captured in a prospective spine registry for patients referred to the department of neurosurgery within a single academic center between July 1, 2017, and November 3, 2020. A spine triage algorithm was developed and implemented January 1, 2018. Healthcare utilization was recorded for 1 year after the first appointment in the department of neurosurgery. Imaging costs were estimated using publicly available data from the Centers for Medicare and Medicaid Services. Statistical analysis consisted of an independent sample t-test or randomization test for continuous variables and a chi-square test for categorical variables.

RESULTS

A total of 3854 patients were included in this study. The mean age was 60 years (50.8% female) and 89.8% had undergone advanced imaging before being referred to the department of neurosurgery. In total, 12.6% of patients were referred with a specific surgical diagnosis (i.e., spinal stenosis, lumbar spondylolisthesis, etc.). During the pretriage phase 1810 patients were enrolled, and there were 2044 patients enrolled after the triage algorithm was implemented. Advanced imaging (CT or MRI) was ordered more frequently by providers before the triage program was initiated, with imaging ordered in 34% (617/1810) of patients pretriage versus 14.8% (302/2044) after the triage pathway was implemented (p < 0.001). The authors calculated a significant reduction in cost associated with reduced radiology utilization. Before triage, the cost of radiology utilization was $85,475/1000 patients compared with $40,107/1000 patients afterward (p < 0.001). The triage program did not change the utilization of surgery (14.6% before, 13.6% after).

CONCLUSIONS

Among patients treated after a spinal triage program was implemented in a single neurosurgery department, there was a substantial reduction in the use of advanced imaging and a 50% reduction in cost associated with outpatient radiology utilization. The triage program did not change the rate of spine surgery being performed.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Verteporfin-loaded microparticles for radiosensitization of preclinical lung and breast metastatic spine cancer

Oluwaseun O. Akinduro, Paola Suarez-Meade, McKinley Roberts, Stephany Y. Tzeng, Rachel Sarabia-Estrada, Paula Schiapparelli, Emily S. Norton, Ziya L. Gokaslan, Panos Z. Anastasiadis, Hugo Guerrero-Cázares, Jordan J. Green, and Alfredo Quiñones-Hinojosa

OBJECTIVE

The vertebral column is the most common site for skeletal metastasis, often leading to debilitating pain and weakness. Metastatic cancer has unique genetic drivers that potentiate tumorigenicity. There is an unmet need for novel targeted therapy in patients with spinal metastatic disease.

METHODS

The authors assessed the effect of verteporfin-induced yes-associated protein (YAP) inhibition on spine metastatic cell tumorigenicity and radiation sensitivity in vitro. Animal studies used a subcutaneous xenograft mouse model to assess the use of systemic intraperitoneal verteporfin (IP-VP) and intratumoral verteporfin microparticles (IT-VP) to inhibit the tumorigenicity of lung and breast spinal metastatic tumors from primary patient-derived tissue.

RESULTS

Verteporfin led to a dose-dependent decrease in migration, clonogenicity, and cell viability via inhibition of YAP and downstream effectors cyclin D1, CTGF, TOP2A, ANDRD1, MCL-1, FOSL2, KIF14, and KIF23. This was confirmed with knockdown of YAP. Verteporfin has an additive response when combined with radiation, and knockdown of YAP rendered cells more sensitive to radiation. The addition of verteporfin to YAP knockdown cells did not significantly alter migration, clonogenicity, or cell viability. IP-VP and IT-VP led to diminished tumor growth (p < 0.0001), especially when combined with radiation (p < 0.0001). Tissue analysis revealed diminished expression of YAP (p < 0.0001), MCL-1 (p < 0.0001), and Ki-67 (p < 0.0001) in tissue from verteporfin-treated tumors compared with vehicle-treated tumors.

CONCLUSIONS

This is the first study to demonstrate that verteporfin-mediated inhibition of YAP leads to diminished tumorigenicity in lung and breast spinal metastatic cancer cells. Targeting of YAP with verteporfin offers promising results that could be translated to human clinical trials.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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A computer vision approach to identifying the manufacturer of posterior thoracolumbar instrumentation systems

Adrish Anand, Alex R. Flores, Malcolm F. McDonald, Ron Gadot, David S. Xu, and Alexander E. Ropper

OBJECTIVE

Knowledge of the manufacturer of the previously implanted pedicle screw systems prior to revision spinal surgery may facilitate faster and safer surgery. Often, this information is unavailable because patients are referred by other centers or because of missing information in the patients’ records. Recently, machine learning and computer vision have gained wider use in clinical applications. The authors propose a computer vision approach to classify posterior thoracolumbar instrumentation systems.

METHODS

Lateral and anteroposterior (AP) radiographs obtained in patients undergoing posterior thoracolumbar pedicle screw implantation for any indication at the authors’ institution (2015–2021) were obtained. DICOM images were cropped to include both the pedicle screws and rods. Images were labeled with the manufacturer according to the operative record. Multiple feature detection methods were tested (SURF, MESR, and Minimum Eigenvalues); however, the bag-of-visual-words technique with KAZE feature detection was ultimately used to construct a computer vision support vector machine (SVM) classifier for lateral, AP, and fused lateral and AP images. Accuracy was tested using an 80%/20% training/testing pseudorandom split over 100 iterations. Using a reader study, the authors compared the model performance with the current practice of surgeons and manufacturer representatives identifying spinal hardware by visual inspection.

RESULTS

Among the three image types, 355 lateral, 379 AP, and 338 fused radiographs were obtained. The five pedicle screw implants included in this study were the Globus Medical Creo, Medtronic Solera, NuVasive Reline, Stryker Xia, and DePuy Expedium. When the two most common manufacturers used at the authors’ institution were binarily classified (Globus Medical and Medtronic), the accuracy rates for lateral, AP, and fused images were 93.15% ± 4.06%, 88.98% ± 4.08%, and 91.08% ± 5.30%, respectively. Classification accuracy decreased by approximately 10% with each additional manufacturer added. The multilevel five-way classification accuracy rates for lateral, AP, and fused images were 64.27% ± 5.13%, 60.95% ± 5.52%, and 65.90% ± 5.14%, respectively. In the reader study, the model performed five-way classification on 100 test images with 79% accuracy in 14 seconds, compared with an average of 44% accuracy in 20 minutes for two surgeons and three manufacturer representatives.

CONCLUSIONS

The authors developed a KAZE feature detector with an SVM classifier that successfully identified posterior thoracolumbar hardware at five-level classification. The model performed more accurately and efficiently than the method currently used in clinical practice. The relative computational simplicity of this model, from input to output, may facilitate future prospective studies in the clinical setting.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)

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Correlation between the spinopelvic type and morphological characteristics of lumbar facet joints in degenerative lumbar spondylolisthesis

*Yebo Leng, Chao Tang, Baoqiang He, Xiamin Pu, Min Kang, Yehui Liao, Qiang Tang, Fei Ma, Qing Wang, and Dejun Zhong

OBJECTIVE

The correlation between the spinopelvic type and morphological characteristics of lumbar facet joints in patients with degenerative lumbar spondylolisthesis (DLS) was investigated.

METHODS

One hundred forty-two patients with L4 DLS were enrolled (DLS group), and 100 patients with lumbar disc herniation without DLS were selected as the control group (i.e., non–lumbar spondylolisthesis [NL] group). Morphological parameters of L4–5 facet joints and L4–5 disc height and angle were measured on 3D reconstructed CT images; namely, the facet joint angle (FJA), pedicle–facet joint angle (PFA), facet joint tropism, and facet joint osteoarthritis (OA). The L4 slip percentage, sacral slope, and lumbar lordosis were measured on radiographs. Patients in the DLS and NL groups were divided into 4 subgroups according to Roussouly classification (types I, II, III, and IV).

RESULTS

In the DLS and NL groups, as the spinopelvic type changed from type II to type IV, the facet joint morphology showed a gradual sagittal orientation in the FJA, a gradual horizontal orientation in the PFA, a gradual severity in OA, and a gradual increase in the slip percentage, but changes were completely opposite from type I to type II. Additionally, compared with the NL group, the facet joint morphology in the DLS group had more horizontal orientation in PFA, more sagittal orientation in the FJA, and the facet joint tropism and OA were more severe.

CONCLUSIONS

Facet joint morphology was correlated with spinopelvic type in the slip segment of DLS. Facet joint morphology was part of the joint configuration in different spinopelvic types, not just the result of joint remodeling after DLS. Moreover, morphological changes of the facet joints and DLS interacted with each other. Additionally, morphological remodeling of the facet joints in DLS played an important role in spinal balance and should be taken into consideration when designing a surgical approach.

In Journal of Neurosurgery: Spine Volume 38: Issue 4 (Apr 2023)