Tag: deformity

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Is the chin-brow vertical angle always a reliable parameter for surgical planning in the correction of thoracolumbar kyphosis secondary to ankylosing spondylitis?

J Neurosurg Spine 44:858–865, 2026

This clinical retrospective study evaluates whether the chin-brow vertical angle (CBVA) reliably predicts the osteotomized vertebra angle (OVA) when planning pedicle subtraction osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis. Patients were stratified by cervical range of motion (CROM) and radiographic changes in CBVA, cervical Cobb angles, and global sagittal parameters were analyzed.

Results show a strong correlation between ΔCBVA and OVA in patients with limited CROM (≤20°), but no correlation when CROM exceeded 20°, indicating that CBVA alone is unreliable for OVA design in patients with flexible cervical spines. The study recommends considering cervical mobility when selecting OVA planning methods and suggests supplementing CBVA with measures of cervical compensation in flexible cases.

Objective Examine how well CBVA predicts needed correction (OVA) in ankylosing spondylitis (AS) thoracolumbar kyphosis across different cervical range of motion (CROM) values.

Design/Groups Retrospective cohort of AS patients undergoing single-level thoracic or lumbar pedicle subtraction osteotomy (PSO) (2015–2019) with ≥2-year follow-up; grouped by CROM: ≤10°, 10–20°, and >20°.

Key finding (CROM ≤20°) Strong correlation between ΔCBVA (preop→immediate postop) and OVA in CROM ≤10° and 10–20° groups (r = 0.881 and 0.932; both p < 0.001), supporting CBVA-based planning when cervical motion is limited.

Key finding (CROM >20°) No correlation between ΔCBVA and OVA when CROM > 20° (r = 0.198, p = 0.314), and most patients (89%) had ΔCBVA smaller than OVA, implying undercorrection risk if CBVA alone guides OVA.

Cervical adaptation mechanism With higher cervical mobility, postoperative cervical alignment changes substantially (CNA group cervical kyphosis change 20.25° vs 4.97° in CA), which can blunt CBVA change despite large osteotomy correction.

Improved predictor Adding cervical alignment change (ΔCobb C0–7) to CBVA change yields closer agreement with OVA (ΔCobb C0–7 + ΔCBVA correlated with OVA in both CA and CNA groups; CA r = 0.87 p < 0.001; CNA r = 0.38 p = 0.044).

Clinical recommendation CBVA is not consistently reliable for OVA design; it is not recommended as a guiding parameter when CROM > 20°.

Outcomes Both cervical-ankylosis–range (CROM ≤20°) and nonankylosis–range (CROM >20°) subgroups achieved satisfactory orthopedic improvement after surgery despite differences in cervical compensation.

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Incidence and risk factors of adjacent segment degeneration in lumbosacral or lumbo-iliac fusion with L2 as the uppermost instrumented vertebra

J Neurosurg Spine 44:693–703, 2026

This clinical retrospective study evaluates the incidence and risk factors for symptomatic adjacent segment degeneration (ASD) after instrumented fusion from L2 to the sacrum or ilium in 89 adults treated for diffuse lumbar degeneration or mild–moderate deformity. Over a mean 38.6-month follow-up, 40% developed symptomatic L1–2 ASD and 23.6% required revision, with Kaplan-Meier ASD-free rates of 79% at 1 year and 59% at 3 years.

Multivariate analysis identified L2–3 decompression, preexisting advanced L1–2 disc degeneration, greater postoperative PI–LL mismatch, and higher lordosis distribution index as independent ASD risk factors; distal failures (13.5%) were linked to male sex, younger age, and absence of iliac screws. The authors recommend careful selection of L2 as UIV, balanced lordosis restoration, and consideration of pelvic fixation to mitigate proximal and distal complications.

Aim Quantify incidence of symptomatic adjacent segment degeneration (ASD) after instrumented fusion from L2 (UIV) to sacrum or ilium and identify associated risk factors.

Design/definition Retrospective review (Jan 2016–Dec 2023) of adults undergoing first-time L2–S1/ilium fusion; symptomatic ASD defined by new/worsening pain or neurologic symptoms with L1–2 degenerative/junctional changes (e.g., disc degeneration/stenosis progression, listhesis, junctional kyphosis, fracture, or UIV fixation failure).

Cohort 89 patients (mean age 68.5 years) with mean follow-up 38.6 months.

ASD incidence 36/89 (40%) developed symptomatic ASD at L1–2; mean time to ASD 21 months; 21/89 (23.6%) required reoperation.

ASD-free survival Kaplan-Meier ASD-free rates: 79% at 1 year, 68% at 2 years, 59% at 3 years (mean ASD-free period 52.8 months).

ASD risk factors Higher ASD risk associated with simultaneous decompression at L2–3, preexisting advanced L1–2 disc degeneration, greater postoperative PI-LL mismatch, and higher lordosis distribution index (LDI).

Distal failure incidence 12/89 (13.5%) developed distal failure (including 9 L5–S1 pseudarthroses, 2 sacral fractures, 1 rod fracture); mean time 19 months.

Distal failure risk factors Male sex, younger age, and lack of iliac screws increased risk of distal failure.

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Does segmental alignment matter? A novel understanding of segmental compensation and reciprocal change following single-level lumbar reconstruction

J Neurosurg Spine 44:72–79, 2026

This clinical study analyzes segmental compensation and reciprocal changes after single-level L5–S1 anterior lumbar interbody fusion in 100 adults with normal preoperative lumbar lordosis. Using intradiscal angle, motion segment angle, and disc heights, the authors show significant index-level lordosis restoration and correlated increases in overall lumbar lordosis at 1 month and 1 year.

The paper documents consistent reciprocal decreases in lordosis at adjacent L4–5 and L3–4 levels, provides predictive linear equations for adjacent-level change based on index-level IDA change, and argues that restoring segmental lordosis may prevent maladaptive compensation and reduce adjacent segment disease risk, while noting limitations and need for longer follow-up.

Segmental Compensation: Adjacent lumbar spine segments compensate for loss of lordosis at a pathologic segment by increasing their own segmental lordosis to maintain overall lumbar lordosis (LL) within the normal range.

Reciprocal Change After Fusion: Restoration of lordosis at the L5–S1 level via anterior lumbar interbody fusion (ALIF) leads to a significant, measurable decrease in segmental lordosis at adjacent levels (L4–5 and L3–4), demonstrating a reciprocal relationship.

Predictive Model: The degree of reciprocal loss of lordosis at adjacent levels can be predicted using linear equations based on the lordosis gain at the fused segment (e.g., 1-year adjacent level decrease in IDA = −0.195 × [index level 1-year IDA change] + 0.332).

Global Alignment Maintenance: Despite significant increases in lordosis at the surgical level, total lumbar lordosis does not increase by the same amount due to compensatory decreases at adjacent levels, maintaining global alignment.

Clinical Implication: Proper restoration of segmental lordosis at the surgical level may help prevent negative consequences of persistent compensation at adjacent segments, potentially reducing the risk of adjacent segment disease.

Study Population: Findings are based on 100 adults with normal preoperative LL (PI–LL < 10°) who underwent single-level L5–S1 ALIF and achieved ≥5° increase in segmental lordosis postoperatively.

Correlation With Outcomes: Changes in lordosis at the surgical segment positively correlate with changes in overall lumbar lordosis at both 1 month and 1 year postoperatively.

Long-Term Impact: The persistence of reciprocal changes at adjacent segments up to 1 year suggests that segmental compensatory mechanisms are durable and may influence long-term spinal health and surgical planning.

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Staged Versus Same-Day Surgery in Circumferential Minimally Invasive Deformity Correction

Neurosurgery 95:1040–1045, 2024

We sought to compare long-term clinical and radiographic outcomes in patients who underwent staged vs same-day circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD).

METHODS: We reviewed staged and same-day cMIS ASD cases in a prospective multi-institution database to compare preoperative and 2-year clinical and radiographic parameters between cohorts.

RESULTS: A total of 85 patients with a 2-year follow-up were identified (27 staged, 58 same-day). Staged patients had more extensive surgeries and greater hospital length of stay (all P < .001). There were no significant differences in preoperative or 2-year postoperative clinical metrics between cohorts. Patients in the staged cohort also had greater preoperative coronal deformity and thus experienced greater reduction in coronal deformity at 2 years (all P < .01).

CONCLUSION: Patients undergoing staged or same-day cMIS correction had similar outcomes at 2 years postoperatively. Staged cMIS ASD correction may be more appropriate in patients with greater deformity, higher frailty, and who require longer, more extensive surgeries.

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Deep learning algorithm for fully automated measurement of sagittal balance in adult spinal deformity

European Spine Journal (2024) 33:4119–4124

Deep learning (DL) algorithms can be used for automated analysis of medical imaging. The aim of this study was to assess the accuracy of an innovative, fully automated DL algorithm for analysis of sagittal balance in adult spinal deformity (ASD).

Material and methods Sagittal balance (sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis and sagittal vertical axis) was evaluated in 141 preoperative and postoperative radiographs of patients with ASD. The DL, landmark-based measurements, were compared with the ground truth values from validated manual measurements.

Results The DL algorithm showed an excellent consistency with the ground truth measurements. The intra-class correlation coefficient between the DL and ground truth measurements was 0.71–0.99 for preoperative and 0.72–0.96 for postoperative measurements. The DL detection rate was 91.5% and 84% for preoperative and postoperative images, respectively.

Conclusion This is the first study evaluating a complete automated DL algorithm for analysis of sagittal balance with high accuracy for all evaluated parameters. The excellent accuracy in the challenging pathology of ASD with long construct instrumentation demonstrates the eligibility and possibility for implementation in clinical routine.

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Single-stage correction of severe scoliosis with syringomyelia: performed with traction assistance without prophylactic neurosurgical decompression

J Neurosurg Spine 41:316–324, 2024

There is still controversy about whether it is necessary to perform prophylactic neurosurgical decompression for severe scoliosis (SS) with syringomyelia (SM) to reduce the risk of neurological complications during subsequent spinal correction. This study aimed to explore the safety and effectiveness of using traction-assisted single-stage spinal correction as a treatment for patients who had SS with SM (SS-SM).

METHODS The patients who had SS-SM without previous neurosurgical intervention and who underwent traction-assisted single-stage posterior spinal correction at a single center were included, and the initial, posttraction, and postoperative clinical data were reviewed. Based on preoperative MRI, the included patients were divided into two categories: those with versus those without Chiari malformation type I (CM-I–related SM [CS] vs idiopathic SM [IS]), and those with a moderate syrinx (MS) versus those with a large syrinx (LS). Different groups’ traction and operation contributions were calculated for comparisons (CS vs IS, MS vs LS).

RESULTS A total of 28 patients were included. The initial mean major scoliosis was 101.0° with a mean flexibility of 21.4%. After the operation, the mean total correction rate for scoliosis was 63.9%. The mean traction and operation contributions were 61.5% and 38.5%, respectively. Most of the patients (75%) underwent spinal corrections without 3-column osteotomies, and only 1 patient reported postoperative regional numbness without motor deficits. No differences were found in the mean total correction rates, traction, and operation contributions when comparing CS versus IS and MS versus LS with the comparable initial clinical data (p > 0.05). More than 50% of the total corrections were achieved by preoperative traction in all groups.

CONCLUSIONS Traction-assisted single-stage spinal correction can safely and effectively correct SS-SM without prophylactic neurosurgical decompression under strict patient selection. Additionally, traction can achieve more than half of the final spinal correction, even for patients with varying sizes of SMs.

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Validation of age-adjusted pelvic incidence minus lumbar lordosis and lordosis distribution index for assessing adjacent-segment disease after short-level lumbar fusion surgery

J Neurosurg Spine 40:143–151, 2024

The purpose of this study was to investigate the influence of sagittal alignment according to age-adjusted pelvic incidence minus lumbar lordosis (PI-LL) and lordosis distribution index (LDI) on the occurrence of adjacent-segment disease (ASD) after lumbar fusion surgery.

METHODS This study retrospectively reviewed 234 consecutive patients with lumbar degenerative diseases who underwent 1- or 2-level lumbar fusion surgery. Demographic and radiographic (preoperative and 3-month postoperative) data were collected and compared between ASD and non-ASD groups. Binary logistic regression analysis was performed to evaluate adjusted associations between potential variables and ASD development. A subanalysis was further conducted to assess their relationships in the range of different PI values.

RESULTS With a mean follow-up duration of 70.6 months (range 60–121 months), 118 patients (50.4%) were diagnosed as having cranial radiological ASD. Univariate analyses showed that older age, 2-level fusion, worse preoperative pelvic tilt and LL, lower pre- and postoperative LDI, and more improvement in sagittal vertical axis were significantly correlated with the occurrence of ASD. No significant differences in the PI-LL and age-adjusted PI-LL (offset) were detected between ASD and non-ASD groups. Multivariate analysis identified postoperative LDI (OR 0.971, 95% CI 0.953–0.989, p = 0.002); 2-level fusion (OR 3.477, 95% CI 1.964–6.157, p < 0.001); and improvement of sagittal vertical axis (OR 0.992, 95% CI 0.985–0.998, p = 0.039) as the independent variables for predicting the occurrence of ASD. When stratified by PI, LDI was identified as an independent risk factor in the groups with low and average PI. Lower segmental lordosis (OR 0.841, 95% CI 0.742–0.954, p = 0.007) could significantly increase the incidence of ASD in the patients with high LDI.

CONCLUSIONS Age-adjusted PI-LL may have limited ability to predict the development of ASD. LDI could exert an important effect on diagnosing the occurrence of ASD in the cases with low and average PI, but segmental lordosis was a more significant risk factor than LDI in individuals with high PI.

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Spinopelvic sagittal compensation in adult cervical deformity

J Neurosurg Spine 39:1–10, 2023

The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity.

METHODS A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2–7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2–T3 Cobb angle ≤ −30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3–S1 ≤ −60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm).

RESULTS Compared with asymptomatic control patients, cervical deformity was associated with increased C0–2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10–L2 Cobb angle −7.0° vs −1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0–2 lordosis (R = −0.57, p < 0.01) and lumbar lordosis (LL) (R = −0.20, p = 0.03). Cervical reconstruction resulted in decreased C0–2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0–2 lordosis (p < 0.01) and postoperative reduction of C0–2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01).

CONCLUSIONS Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.

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Crossing the cervicothoracic junction: an evaluation of radiographic alignment, functional outcomes, and patient-reported outcomes

J Neurosurg Spine 38:653–661, 2023

There is currently no consensus regarding the appropriate lower instrumented vertebra (LIV) for multilevel posterior cervical fusion (PCF) constructs between C7 and crossing the cervicothoracic junction (CTJ). The goal of the present study was to compare postoperative sagittal alignment and functional outcomes among adult patients presenting with cervical myelopathy undergoing multilevel PCF terminating at C7 versus spanning the CTJ.

METHODS A single-institution retrospective analysis (January 2017–December 2018) was performed of patients undergoing multilevel PCF for cervical myelopathy that involved the C6–7 vertebrae. Pre- and postoperative cervical spine radiographs were analyzed for cervical lordosis, cervical sagittal vertical axis (cSVA), and first thoracic (T1) vertebral slope (T1S) in two randomized independent trials. Modified Japanese Orthopaedic Association (mJOA) and Patient-Reported Outcomes Measurement Information System (PROMIS) scores were used to compare functional and patient-reported outcomes at the 12-month postoperative follow-up.

RESULTS Sixty-six consecutive patients undergoing PCF and 53 age-matched controls were included in the study. There were 36 patients in the C7 LIV cohort and 30 patients in the LIV spanning the CTJ cohort. Despite significant correction, patients undergoing fusion remained less lordotic than asymptomatic controls, with a C2–7 Cobb angle of 17.7° versus 25.5° (p < 0.001) and a T1S of 25.6° versus 36.3° (p < 0.001). The CTJ cohort had superior alignment corrections in all radiographic parameters at the 12-month postoperative follow-up compared with the C7 cohort: increase in T1S (ΔT1S 14.1° vs 2.0°, p < 0.001), increase in C2–7 lordosis (ΔC2–7 lordosis 11.7° vs 1.5°, p < 0.001), and decrease in cSVA (ΔcSVA 8.9 vs 5.0 mm, p < 0.001). There were no differences in the mJOA motor and sensory scores between cohorts pre- and postoperatively. The C7 cohort reported significantly better PROMIS scores at 6 months (22.0 ± 3.2 vs 11.5 ± 0.5, p = 0.04) and 12 months (27.0 ± 5.2 vs 13.5 ± 0.9, p = 0.01) postoperatively.

CONCLUSIONS Crossing the CTJ may provide a greater cervical sagittal alignment correction in multilevel PCF surgeries. However, the improved alignment may not be associated with improved functional outcomes as measured by the mJOA scale. A new finding is that crossing the CTJ may be associated with worse patient-reported outcomes at 6 and 12 months of postoperative follow-up as measured by the PROMIS, which should be considered in surgical decision-making. Future prospective studies evaluating long-term radiographic, patient-reported, and functional outcomes are warranted.

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Predictors for cervical kyphotic deformity following laminoplasty: a systematic review and meta-analysis

J Neurosurg Spine 38:4–13, 2023

Laminoplasty is a common treatment for cervical spondylotic myelopathy (CSM) and for ossification of the posterior longitudinal ligament (OPLL). However, approximately 21% of patients undergoing laminoplasty develop cervical kyphotic deformity (KD). Because of the high prevalence rate of KD, several studies have sought to identify predictors for this complication, but the findings remain highly inconsistent. Therefore, the authors performed a systematic review and meta-analysis to establish reliable preoperative predictors of KD.

METHODS PubMed, Scopus, and Web of Science databases were used to systematically extract potential references. The first phase of screening required the studies to be written in the English language, involve patients treated for CSM and/or OPLL via laminoplasty, and report postoperative cervical KD. The second phase required the studies to provide more than 10 patients and include a control group. The mean difference (MD) and odds ratio (OR) were calculated for continuous and dichotomous parameters. Study quality was evaluated using the Newcastle-Ottawa Scale. CSM and OPLL patients were further assessed by performing subgroup analyses.

RESULTS Thirteen studies comprising patients who developed cervical KD (n = 296) and no KD (n = 1254) after receiving cervical laminoplasty for CSM or OPLL were included in the meta-analysis. All studies were retrospective cohorts and were rated as high quality. In the combined univariate analysis of CSM and OPLL patients undergoing laminoplasty, statistically significant predictors for postoperative KD included age (MD 2.22, 95% CI 0.16–4.27, p = 0.03), preoperative BMI (MD 0.85, 95% CI 0.06–1.63, p = 0.04), preoperative C2–7 range of flexion (MD 10.42, 95% Cl 4.24–16.59, p = 0.0009), preoperative C2–7 range of extension (MD −4.59, 95% CI −6.34 to −2.83, p < 0.00001), and preoperative center of gravity of the head to the C7 sagittal vertical axis (MD 26.83, 95% CI 9.13–44.52, p = 0.003). Additionally, among CSM patients, males were identified as having a greater risk for postoperative KD (OR 1.73, 95% CI 1.02–2.93, p = 0.04).

CONCLUSIONS The findings from this study currently provide the largest and most reliable review on preoperative predictors for cervical KD after laminoplasty. Given that several of the included studies identified optimal cutoff points for the variables that are significantly associated with KD, further investigation into the development of a preoperative risk scoring system that can accurately predict KD in the clinical setting is encouraged.

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Novel artificial intelligence algorithm: an accurate and independent measure of spinopelvic parameters

J Neurosurg Spine 37:893–901, 2022

The analysis of sagittal alignment by measuring spinopelvic parameters has been widely adopted among spine surgeons globally, and sagittal imbalance is a well-documented cause of poor quality of life. These measurements are time-consuming but necessary to make, which creates a growing need for an automated analysis tool that measures spinopelvic parameters with speed, precision, and reproducibility without relying on user input. This study introduces and evaluates an algorithm based on artificial intelligence (AI) that fully automatically measures spinopelvic parameters.

METHODS Two hundred lateral lumbar radiographs (pre- and postoperative images from 100 patients undergoing lumbar fusion) were retrospectively analyzed by board-certified spine surgeons who digitally measured lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The novel AI algorithm was also used to measure the same parameters. To evaluate the agreement between human and AI-automated measurements, the mean error (95% CI, SD) was calculated and interrater reliability was assessed using the 2-way random single-measure intraclass correlation coefficient (ICC). ICC values larger than 0.75 were considered excellent.

RESULTS The AI algorithm determined all parameters in 98% of preoperative and in 95% of postoperative images with excellent ICC values (preoperative range 0.85–0.92, postoperative range 0.81–0.87). The mean errors were smallest for pelvic incidence both pre- and postoperatively (preoperatively −0.5° [95% CI −1.5° to 0.6°] and postoperatively 0.0° [95% CI −1.1° to 1.2°]) and largest preoperatively for sacral slope (−2.2° [95% CI −3.0° to −1.5°]) and postoperatively for lumbar lordosis (3.8° [95% CI 2.5° to 5.0°]).

CONCLUSIONS Advancements in AI translate to the arena of medical imaging analysis. This method of measuring spinopelvic parameters on spine radiographs has excellent reliability comparable to expert human raters. This application allows users to accurately obtain critical spinopelvic measurements automatically, which can be applied to clinical practice. This solution can assist physicians by saving time in routine work and by avoiding error-prone manual measurements.

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Change in sagittal alignment after decompression alone in patients with lumbar spinal stenosis without significant deformity

J Neurosurg Spine 37:57–63, 2022

The authors’ objective was to investigate whether sagittal balance improves in patients with spinal stenosis after decompression alone.

METHODS This prospective longitudinal cohort study compared preoperative and 6-month postoperative 36-inch full-length radiographs in patients aged older than 60 years. Patients underwent decompression alone for central lumbar spinal stenosis with either a minimally invasive bilateral laminotomy for central decompression, unilateral laminectomy as an over-the-top procedure for bilateral decompression, or traditional wide laminectomy with removal of the spinous processes on both sides. The following radiographic parameters were measured: sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), PI-LL mismatch, coronal Cobb angle, and sacral slope (SS). Patient reported outcome measures (PROMs) were collected, including scores on the Oswestry Disability Index (ODI), visual analog scale (VAS) for leg and back pain, and EQ-5D.

RESULTS Forty-five patients (24 males) with a mean ± SD age of 71.8 ± 5.6 years were included. Sagittal balance showed statistically significant improvement, with the mean SVA decreasing from 52.3 mm preoperatively to 33.9 mm postoperatively (p = 0.0001). The authors found an increase in LL, from mean −41.5° preoperatively to −43.9° postoperatively, but this was not statistically significant (p = 0.055). A statistically significant decrease in PI-LL mismatch from mean 8.4° preoperatively to 5.8° postoperatively was found (p = 0.002). All PROM scores showed significant improvement after spinal decompression surgery. The correlations between SVA and all PROMs were statistically significant at both preoperative and postoperative time points, although most correlations were weak except for those between preoperative SVA and ODI (r = 0.55) and between SVA and VAS for leg pain (r = 0.58).

CONCLUSIONS Sagittal balance and PROMs show improvement at short-term follow-up evaluations in patients who have undergone decompression alone for lumbar spinal stenosis.

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Change in sagittal alignment after decompression alone in patients with lumbar spinal stenosis without significant deformity: a prospective cohort study

J Neurosurg Spine 37:57–63, 2022

OBJECTIVE The authors’ objective was to investigate whether sagittal balance improves in patients with spinal stenosis after decompression alone.

METHODS This prospective longitudinal cohort study compared preoperative and 6-month postoperative 36-inch full-length radiographs in patients aged older than 60 years. Patients underwent decompression alone for central lumbar spinal stenosis with either a minimally invasive bilateral laminotomy for central decompression, unilateral laminectomy as an over-the-top procedure for bilateral decompression, or traditional wide laminectomy with removal of the spinous processes on both sides. The following radiographic parameters were measured: sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), PI-LL mismatch, coronal Cobb angle, and sacral slope (SS). Patient reported outcome measures (PROMs) were collected, including scores on the Oswestry Disability Index (ODI), visual analog scale (VAS) for leg and back pain, and EQ-5D.

RESULTS Forty-five patients (24 males) with a mean ± SD age of 71.8 ± 5.6 years were included. Sagittal balance showed statistically significant improvement, with the mean SVA decreasing from 52.3 mm preoperatively to 33.9 mm postoperatively (p = 0.0001). The authors found an increase in LL, from mean −41.5° preoperatively to −43.9° postoperatively, but this was not statistically significant (p = 0.055). A statistically significant decrease in PI-LL mismatch from mean 8.4° preoperatively to 5.8° postoperatively was found (p = 0.002). All PROM scores showed significant improvement after spinal decompression surgery. The correlations between SVA and all PROMs were statistically significant at both preoperative and postoperative time points, although most correlations were weak except for those between preoperative SVA and ODI (r = 0.55) and between SVA and VAS for leg pain (r = 0.58).

CONCLUSIONS Sagittal balance and PROMs show improvement at short-term follow-up evaluations in patients who have undergone decompression alone for lumbar spinal stenosis.

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Usefulness of anterior column release for segmental lordosis restoration in degenerative lumbar kyphosis

J Neurosurg Spine 36:422–428, 2022

Three-column osteotomies (3COs) for surgical correction of lumbar kyphosis show a strong correction capacity, but this procedure carries high morbidity rates. The anterior column release (ACR) technique was developed as a less invasive procedure. In this study the authors aimed to evaluate sagittal alignment restoration using ACR and to determine factors that affect the degree of correction.

METHODS This study included 36 patients (68 cases) who underwent ACR of more than one level for adult spinal deformity. Parameters for regional sagittal alignment included segmental lordosis (SL). The parameters for global sagittal alignment included pelvic incidence, lumbar lordosis, sacral slope, pelvic tilt, and sagittal vertical axis (SVA). In addition, the interdiscal height (IDH) and difference of interdiscal angle (DIDA) were measured to evaluate the stiffness of the vertebra segment. The changes in SL were evaluated after ACR and the change of global sagittal alignment was also determined. Factors such as the location of the ACR level, IDH, DIDA, cage height, and additional posterior column osteotomy (PCO) were analyzed for correlation with the degree of SL correction.

RESULTS Thirty-six patients were included in this study. A total of 68 levels were operated with the ACR (8 levels at L2–3, 27 levels at L3–4, and 33 levels at L4–5). ACR was performed for 1 level in 10 patients, 2 levels in 20, and 3 levels in 6 patients (mean 1.9   0.7 levels per patient). Mean follow-up duration was 27.1   4.2 months. The mean SL of the total segment was 0.4    7.2  preoperatively and increased by 15.3    5.5  at the last follow-up (p < 0.001); thus, the mean increase of SL was 14.9    8.1  per one ACR. Global sagittal alignment was also improved following SL restoration with SVA from 101.9 mm to 31.4 mm. The degree of SL correction was correlated with the location of ACR level (p = 0.041) and was not correlated with IDH, DIDA, cage height and additional PCO.

CONCLUSIONS This study demonstrated that the mean correction angle of SL was 14.9 per one ACR. The degree of disc space collapse and stiffness of segment did not affect the degree of correction by ACR.

 

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Safety of lateral access to the concave side for adult spinal deformity

J Neurosurg Spine 35:100–104, 2021

Minimally invasive surgery (MIS) techniques, particularly lateral lumbar interbody fusion (LLIF), have become increasingly popular for adult spinal deformity (ASD) correction. Much discussion has been had regarding theoretical and clinical advantages to addressing coronal curvature from the convex versus concave side of the curve. In this study, the authors aimed to broadly evaluate the clinical outcomes of addressing ASD with circumferential MIS (cMIS) techniques while accessing the lumbar coronal curvature from the concave side.

METHODS A multi-institution, retrospective chart and radiographic review was performed for all ASD patients with at least a 10° curvature, as defined by the Scoliosis Research Society, who underwent cMIS correction. The data collected included convex versus concave access to the coronal curve, durable or sensory femoral nerve injury lasting longer than 6 weeks, vascular injury, visceral injury, and any additional major complication, with at least a 2-year follow-up. Neither health-related quality-of-life metrics nor spinopelvic parameters were included within the scope of this study.

RESULTS A total of 152 patients with ASD treated with cMIS correction via lateral access were identified and analyzed. Of these, 126 (82.9%) were approached from the concave side and 26 (17.1%) were approached from the convex side. In the concave group, 1 (0.8%) motor and 4 (3.2%) sensory deficit cases remained at 6 weeks after the operation. No vascular, visceral, or catastrophic intraoperative injuries were encountered in the concave group. Of the 26 patients in the convex group, 2 (7.7%) experienced motor deficits lasting longer than 6 weeks and 5 (19.2%) had lower-extremity sensory deficits.

CONCLUSIONS It has been reported that lateral access to the convex side is associated with similar clinical and radiographic outcomes with fewer complications when compared with access to the concave side. Advantages to approaching the lumbar spine from the concave side include using one incision to access multiple levels, breaking the operative table to assist with curvature correction, easier access to the L4–5 disc space, the ability to release the contracted side, and, often, avoidance of the need to access or traverse the thoracic cavity. This study illustrates the largest reported cohort of concave access for cMIS scoliosis correction; few postoperative sensory and motor deficits were found.

 

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Augmented reality–mediated stereotactic navigation for execution of en bloc lumbar spondylectomy osteotomies

J Neurosurg Spine 34:700–705, 2021

En bloc spinal tumor resections are technically demanding procedures with high morbidity because of the conventionally large exposure area and aggressive resection goals. Stereotactic surgical navigation presents an opportunity to perform the smallest possible resection plan while still achieving an en bloc resection.

Augmented reality (AR)–mediated spine surgery (ARMSS) via a mounted display with an integrated tracking camera is a novel FDA-approved technology for intraoperative “heads up” neuronavigation, with the proposed advantages of increased precision, workflow efficiency, and cost-effectiveness. As surgical experience and capability with this technology grow, the potential for more technically demanding surgical applications arises.

Here, the authors describe the use of ARMSS for guidance in a unique osteotomy execution to achieve an en bloc wide marginal resection of an L1 chordoma through a posterior-only approach while avoiding a tumor capsule breach. A technique is described to simultaneously visualize the navigational guidance provided by the contralateral surgeon’s tracked pointer and the progress of the BoneScalpel aligned in parallel with the tracked instrument, providing maximum precision and safety. The procedure was completed by reconstruction performed with a quad-rod and cabled fibular strut allograft construct, and the patient did well postoperatively.

Finally, the authors review the technical aspects of the approach, as well as the applications and limitations of this new technology.

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Evolution of Sagittal Imbalance Following Corrective Surgery for Sagittal Plane Deformity

Neurosurgery 81:129–134, 2017

Sagittal balance in adult spinal deformity is a major predictor of quality of life. A temporary loss of paraspinalmuscle force and somatic pain following spine surgery may limit a patient’s ability to maintain posture.

OBJECTIVE: To assess the evolution of sagittal balance and clinical outcomes during recovery from adult spinal deformity surgery.

METHODS: Retrospective review of a prospective observational database identified a consecutive series of patients with sagittal vertical axis (SVA) > 40mm undergoing adult deformity surgery. Radiographic parameters and clinical outcomes were measured out to 2 yr after surgery.

RESULTS: A total of 113 consecutive patients met inclusion criteria. Mean preoperative SVA was 90.3 mm, increased to 104.6mm in the first week, then gradually reduced at each follow-up interval to 59.2mm at 6wk, 45.0mm at 3mo, 38.6mm at 6mo, and 34.1mm at 1 yr (all P < .05). SVA did not change between 1 and 2 yr. Pelvic incidence-lumbar lordosis (PI-LL) corrected immediately from 25.3◦ to 8.5◦ (16.8◦ change; P < .01) and a decreased pelvic tilt from 27.6◦ to 17.6◦ (10◦ change; P < .01). No further change was noted in PILL. Pelvic tilt increased to 20.2◦ (P = .01) at 6wk and held steady through 2 yr. Mean Visual Analog Scale, Oswestry Disability Index, and Short Form-36 scores all improved; pain rapidly improved, whereas disability measures improved as SVA improved.

CONCLUSION: Radiographic assessment of global sagittal alignment did not fully reflect surgical correction of sagittal balance until 6 months after adult deformity surgery. Sagittal balance initially worsened then steadily improved at each interval over the first year postoperatively. At 1 yr, all clinical and radiographic measures outcomes were significantly improved.

 

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Surgical treatment of pathological loss of lumbar lordosis (flatback)

Flatback

J Neurosurg Spine 21:160–170, 2014

Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence–lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors’ objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM.

Methods. The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form–36 scores, and Scoliosis Research Society–22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed.

Results. A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form–36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated –1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed.

Conclusions. Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

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A standardized nomenclature for cervical spine soft-tissue release and osteotomy for deformity correction

Standardized nomenclature cervical osteotomies

J Neurosurg Spine 19:269–278, 2013

Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors’ objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons.

METHODS

A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients.

RESULTS

The average intrarater reliability was classified as “almost perfect agreement” for the major osteotomy (0.89 [range 0.60–1.00]) and approach modifier (0.99 [0.95–1.00]); it was classified as “moderate agreement” for the minor osteotomy (0.73 [range 0.41–1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 (“almost perfect agreement”); approach modifier, 0.99 (“almost perfect agreement”); and minor osteotomy, 0.55 (“moderate agreement”). Analysis of only major osteotomy plus approach modifier yielded a classification that was “almost perfect” with an average intrarater reliability of 0.90 (0.63–1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews.

CONCLUSIONS

The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

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Effects of age on perioperative complications of extensive multilevel thoracolumbar spinal fusion surgery

J Neurosurg Spine 12:402–408, 2010. DOI: 10.3171/2009.10.SPINE08741

The elderly compose a substantial proportion of patients presenting with complex spinal pathology. Several recent studies have suggested that fusion of 4 or more levels increases the risk of perioperative complications in elderly patients. Therefore, the purpose of this study was to analyze the effects of age in persons undergoing multilevel (≥ 5 levels) thoracolumbar fusion surgery.

Methods. A retrospective review of all hospital records, operative reports, and clinic notes was conducted for 124 consecutive patients who underwent surgery between 2000 and 2007 with an average follow-up of 3.5 years and a minimum follow-up of 1.2 years. The most frequent preoperative diagnoses included scoliosis, tumor, osteomyelitis, vertebral fracture, and degenerative disc disease with stenosis. Complications were classified as intraoperative and major and minor postoperative as well as the need for revision surgery. Multivariate logistic regression analysis was used to determine the effects of age and other potentially prognostic factors.

Results. After controlling for other factors, increasing age was associated with an elevated risk for major postoperative complications (OR 1.04, 95% CI 1.00–1.10) as were increasing levels of fusion (OR 1.5, 95% CI 1.1–2.1) and male sex (OR 4.6, 95% CI 1.3–16.2). In patients 65 years of age or older, rates of intraoperative complications, major and minor postoperative complications, and reoperation were 14.1, 23.4, 29.7, and 26.6%, respectively. The number of comorbidities was associated with a greater risk for perioperative complications in elderly patients (OR 1.8, 95% CI 1.1–2.8).

Conclusions. Age is a positive risk factor for major postoperative complications in extensive thoracolumbar spinal fusion surgery. Complication rates in the elderly are high, and good clinical judgment and careful patient selection are needed before performing extensive thoracolumbar reconstruction in older persons.

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