Pennington, Zach

OBJECTIVE Pelvic incidence (PI) is a key parameter of sagittal alignment. While conventionally held to be fixed, increasing evidence suggests PI may be variable. This study aimed to identify predictors of change in PI with patient position and to assess the association of preoperative radiographic characteristics and intraoperative maneuvers with postoperative PI. METHODS Patients who underwent thoracolumbosacral fusion were identified, and data were gathered on preoperative spinopelvic parameters, patient demographic characteristics, and operative details. Preoperative spinopelvic parameters were measured on upright, supine, and prone radiographs. Univariable comparisons of PI between the different patient positions were performed. Multivariable analysis was performed to identify variables independently correlated with PI on 6-week postoperative radiographs. Change in PI was defined as ≥ 5° change between positions. RESULTS In total, 138 patients were identified (mean ± SD age 66.0 ± 8.7 years; 38.4% male). Statistically significant differences in PI were noted between preoperative standing and supine (mean −3.2° ± 4.2°, p < 0.001), preoperative supine and prone (3.5° ± 4.7°, p < 0.001), preoperative and 6-week postoperative standing (1.5° ± 6.2°, p = 0.01), and immediate and 6-week upright (1.1° ± 3.9°, p = 0.007) radiographs. Univariable comparisons showed PI decrease from standing to supine was predicted only by weight (87.0 ± 15.0 vs 81.1 ± 19.3 kg, p = 0.04); there were no significant predictors of increase in PI from standing to prone. Increase in PI from preoperative to 6-week standing radiographs was predicted by lower preoperative PI class (p < 0.001), L5/S1 interbody placement (74.4% vs 52.0%, p = 0.02), and change in PI from preoperative standing to supine (12.8% vs 39.8%, p = 0.002) and from standing to prone (51.3% vs 13.3%, p < 0.001). Multivariable analysis showed that 6-week postoperative PI was associated with only preoperative supine PI (B = 0.293, 95% CI 0.10–0.48, p = 0.003) and prone PI (B = 0.647, 95% CI 0.44–0.85, p < 0.001). CONCLUSIONS There are position-dependent changes in PI among patients without prior pelvic fixation. Statistically significant changes in PI are seen even after pelvic fixation with a single S2-alar-iliac screw bilaterally. Postoperative PI was best predicted by preoperative PI on supine and prone radiographs rather than upright radiographs, suggesting that preoperative prone and supine radiographs may provide surgeons with the best information for achieving PI–lumbar lordosis mismatch < 10°.

OBJECTIVE Transforaminal lumbar interbody fusion (TLIF) offers both indirect decompression and segmental correction through restoration of disc height. However, stresses exerted on the vertebral endplates by the interbody device can result in implant subsidence and loss of correction. The present time-to-event analysis aimed to identify predictors of interbody subsidence. METHODS Patients who underwent 1- or 2-level TLIF were identified. Data on demographics, surgical details, preoperative bone quality using CT-based Hounsfield units (HU), and pre- and postoperative lumbopelvic parameters were collected. Univariable analyses were conducted to identify predictors of subsidence (≥ 2-mm intrusion of interbody into cranial or caudal vertebrae) and significant subsidence (≥ 4-mm intrusion). Multivariable Cox regression was performed to identify independent predictors of subsidence, expressed as hazard ratios with 95% confidence intervals. RESULTS A total of 198 patients treated at 241 levels were included (median age 66.6 years, IQR 59.5, 73.7 years; 56.6% were women). In 92 levels (38.2%) there was some subsidence and in 25 (10.4%) there was significant subsidence. Implanted levels demonstrating subsidence (≥ 2 mm) were associated with lower HU in cranial and caudal vertebrae; had interbodies positioned farther from the anterior apophyseal ring; were implanted with taller, more lordotic interbodies; and underwent greater disc height restoration. Those showing significant subsidence (≥ 4 mm) were similarly associated with lower HU in the cranial and caudal vertebrae; had interbodies positioned farther from the anterior apophyseal ring of the caudal vertebrae; and underwent greater disc height restoration. Multivariable Cox regression showed that time to subsidence was predicted by greater implant height (HR 1.20/mm, 95% CI 1.05–1.38; p = 0.009), greater postoperative disc height (HR 1.21/mm, 95% CI 1.09–1.34; p < 0.001), and greater disc height restoration (HR 1.11/mm, 95% CI 1.04–1.19; p = 0.002). The time-to-subsidence analysis for significant (≥ 4 mm) subsidence showed that it was predicted by lower HU in the cranial vertebrae (HR 0.98/unit, 95% CI 0.97–0.99; p = 0.001); increasing number of levels instrumented (HR 1.26, 95% CI 1.04–1.52; p = 0.016); and greater disc height restoration (HR 1.33/mm, 95% CI 1.18–1.51; p < 0.001). CONCLUSIONS This time-to-event analysis suggests that interbody subsidence following TLIF is best predicted by implantation of a taller interbody and aggressive disc height restoration. Significant subsidence is similarly predicted by aggressive disc height restoration along with poor baseline bone quality. The results suggest the need to balance aggressive correction at the time of surgery against the increased risk of subsequent interbody subsidence.

Introduction: Bone health optimization is a key component of the preoperative management of spine surgery patients, as poor bone quality increases the odds of mechanical complications. The present study aimed to achieve the following: (1) compare the relative efficacy of current osteoporosis medications in improving bone quality; (2) identify factors influencing treatment response in preoperative spine surgery patients. Methods: Patients treated at a single, multisite institution who received osteoporosis treatment were identified. Data were gathered on pre- and post-treatment lumbar spine Hounsfield Unit (HU) measurements, patient demographics, frailty scores (modified Frailty Index/mFI, risk analysis index/RAI), and pharmacologic treatment details. The primary outcome was a ≥7 point improvement in lumbar HU, and baseline and logistic regression models were utilized to identify factors associated with this improvement. Medications were grouped as anabolic (teriparatide, romosozumab) and antiresorptive (denosumab, alendronate) therapies. Results: A total of 267 patients were included (median age: 74 years; IQR [66–81]; 67.3% female), with 127 (47.6%) improving by ≥7 HU. The treatment agents used were alendronate (95), denosumab (113), romosozumab (31), and teriparatide (28). Univariable comparisons revealed significant differences across medication groups in age (p < 0.001), sex (p < 0.001), mFI (p < 0.001), RAI (p = 0.004), BMI (p < 0.001), pre-treatment HU (p = 0.022), and treatment duration (p < 0.001). The highest HU improvement rates (ΔHU ≥ 7) were observed in patients receiving the anabolic medications romosozumab (67.7%) and teriparatide (60.7%). Univariable logistic regression identified male sex (OR 0.54, p = 0.019), higher pre-treatment HU (OR 0.99, p = 0.006), and longer treatment duration (OR 0.97, p = 0.003) as factors associated with lower odds of HU improvement. Only romosozumab was associated with significantly higher odds of HU improvement relative to alendronate (OR 3.02, p = 0.012). In our multivariable analysis, male sex (OR 0.53, p = 0.028) and higher pre-treatment HU (OR 0.99, p = 0.002) remained significant predictors of HU improvement. However, medication type was not significant in the multivariable analysis. Conclusions: Our study highlights that male sex and higher pre-treatment HU were independently associated with lower odds of HU improvement, while medication type was not a significant predictor. Additionally, anabolic agents offered superior improvement relative to antiresorptive therapies.

Background As the population continues to age, the number of adults receiving care for hydrocephalus is expected to increase. Here, we assess trends in the utilization and physician reimbursement for ventriculoperitoneal shunts (VPS), lumboperitoneal shunting (LPS), and endoscopic third ventriculostomy (ETV) for adult hydrocephalus. Methods The Medicare Part B National Summary Data files from 2000 to 2021 were collected, and information was extracted on procedures performed per year, total charges billed, and actual payments. Linear mixed-model regression analyses were conducted to assess the significance of changes in procedural volume and physician reimbursement over time while adjusting for inflation. Results Over the period studied, there was a 26% increase in VPS placement (P = 0.11), 11.34% increase in ETV utilization (P < 0.01), and 43.1% decrease in LPS utilization (P < 0.01). This corresponded to annualized changes of + 4.29% for ETV procedures, −8.78% for LPS, and + 45.8% for VPS. There was a statistically significant difference in the change of rate of number of procedures annually between LPS and VPS (P = 0.04). In both inflation-unadjusted and inflation-adjusted analyses, all procedures experienced an annual decline in reimbursement with inflation-adjusted changes of −11.54%/year for ETV, −4.13% for LPS, and −13.12% for VPS. There was a statistically significant difference in the change of rate of reimbursement between LPS procedures and both ETV (P < 0.01) and VPS (P < 0.01). Conclusion Medicare reimbursement data shows that a commensurate decline in physician reimbursement has accompanied the ongoing rise in adult hydrocephalus procedures.

OBJECTIVE The aim of this study was to determine independent risk factors for vertebral compression fracture (VCF) following stereotactic body radiation therapy (SBRT) in metastatic spine disease. METHODS Patients treated with SBRT for spinal metastasis at a single tertiary care center between 2008 and 2019 were retrospectively identified. Patients with CT scans obtained within 1 year of SBRT completion were included. Variables collected included demographics, Spine Instability Neoplastic Score (SINS), primary tumor pathology, Weinstein-Boriani-Biagini (WBB) classification, chemoradiation treatment details, and bone quality as assessed by Hounsfield units (HUs) on CT. HUs were measured for the medullary bone of the metastatic level, the tumor, and the vertebral bodies cephalad and caudal to the metastasis. Multivariable logistic regression was used to identify predictors of post-SBRT pathological fracture. RESULTS A total of 292 patients (mean age 66 years) with 392 unique lesions were included. The most common pathologies were prostate (n = 193), kidney/renal cell (n = 46), and lung (n = 33). The most common tumor levels were thoracic (n = 206 lesions) and lumbar (n = 128 lesions). SBRT was generally delivered in 1–3 fractions with doses ranging from 16 to 24 Gy in 1 fraction and 24–36 Gy in 3 fractions. Of the 392 lesions, 73 suffered VCF: 21 (29%) with < 25% height loss, 15 (21%) with 25%–40% height loss, and 37 (51%) with > 40% height loss. On univariate analysis, patients with VCF had lower average HUs (156 ± 52 vs 202 ± 89, p < 0.001), more WBB sectors involved (3 ± 2 vs 3 ± 1, p < 0.001), higher SINSs (8 ± 3 vs 6 ± 2, p < 0.001), were more commonly female (33% vs 22%, p = 0.05), and more commonly had nonprostate pathology (67% vs 47%, p = 0.003). VCF rates were similar between moderate (< 20 Gy in 1 fraction, < 30 Gy in 3 or 5 fractions) and high-dose (> 20 Gy in 1 fraction, > 30 Gy in 3 or 5 fractions) radiation schema (15% VCF vs 16% no VCF, respectively; p = 0.99). On multivariable logistic regression, independently significant predictors of VCF were HUs ≤ 229 (OR 6, p < 0.001), affected levels ≥ 3 WBB segments (OR 3, p < 0.001), and an SINS ≥ 8 (OR 2, p = 0.02). CONCLUSIONS Low pre-radiation HUs, involvement of more WBB sectors, and a higher SINS were independent predictors of VCF following SBRT for metastatic spine disease.

BACKGROUND AND OBJECTIVES: The Risk Analysis Index (RAI) is a comprehensive assessment of frailty for predicting neurosurgical outcomes. The aim of this study was to assess whether frailty, measured by a modified RAI (mRAI), was an independent predictor of adverse events (AEs), nonroutine discharge (NRD), and in-hospital mortality for patients with acute cervical spinal cord injuries (SCIs). METHODS: A retrospective cohort study was performed using the American College of Surgeons Trauma Quality Programs database. Adult patients with acute cervical SCI from 2016 to 2022 were stratified by mRAI score into 3 groups: Robust (mRAI 0-10), Frail (mRAI 11-20), and Very Frail (mRAI ≥21). Patient demographics, comorbidities, injury type, diagnostic and treatment modality, AEs, and in-hospital mortality were assessed. A multivariate logistic regression analysis was used to identify independent predictors of AEs, NRD, and in-hospital mortality. RESULTS: 71 048 patients were stratified by mRAI score: 59 796 Robust (84.2%), 9558 Frail (13.5%), and 1694 Very Frail (2.4%). The proportion of SCIs secondary to a fall (Robust: 44.1% vs Frail: 70.2% vs Very Frail: 82.3%; P < .001) and AEs (Robust: 21.5% vs Frail: 24.4% vs Very Frail: 25.0%; P < .001) significantly increased with frailty. Very Frail patients experienced higher NRDs (Robust: 72.3% vs Frail: 85.2% vs Very Frail: 91.0%; P < .001) and in-hospital mortality (Robust: 10.9% vs Frail: 18.3% vs Very Frail: 29.2%; P < .001). On multivariate regression analysis, both Frail (odds ratio [OR]: 1.42; 95% CI: 1.25-1.61; P < .001) and Very Frail (OR: 2.09; 95% CI: 1.46-2.99; P < .001) mRAI scores predicted NRD, but only Frail mRAI score (OR: 1.12; 95% CI: 1.05-1.21; P = .001) was significantly associated with AEs. In addition, Frail (OR: 1.50; 95% CI: 1.36-1.65; P < .001) and Very Frail (OR: 2.79; 95% CI: 2.36-3.29; P < .001) mRAI scores were independent predictors of in-hospital mortality. CONCLUSION: Our study suggests that mRAI may be used to assess morbidity and mortality in patients presenting with spinal cord injury.

OBJECTIVE The purpose of this study was to determine risk factors for distal junctional failure (DJF) following three-column osteotomy (3CO) for the correction of cervical deformity. METHODS A retrospective review was performed of patients who underwent a cervical or upper thoracic 3CO for cervical deformity correction by the senior author from 2008 to 2023. The main outcome of interest was DJF, defined as revision surgery with extension of the distal end of the fusion construct. Patients were excluded if the lowest instrumented vertebra (LIV) was the sacrum/pelvis, and if patients had prior autofusion throughout the distal part of the spine to the sacrum (e.g., ankylosing spondylitis). The minimum follow-up duration was 1 year. RESULTS One hundred fourteen patients were identified who underwent a cervical or upper thoracic 3CO for cervical deformity correction, 41 of whom met inclusion criteria for this study. The median patient age was 66 years, median BMI was 27, and 61% were male. Ten patients (24%) experienced DJF, requiring reoperation and distal extension of the construct to the pelvis in 9 cases and to L1 in 1 case. On univariable analysis, patients who experienced DJF compared with those who did not were more likely to be female (80% vs 35%, p = 0.007), had lower LIV Hounsfield units (HUs; 127 vs 167, p = 0.041), were less likely to have an LIV in a small autofused segment (10% vs 45%, p = 0.02), had an LIV that was closer to the first lordotic level (one level above vs three, p = 0.043), and had a longer length of fusion (17 vs 13 levels, p = 0.033). A stepwise multivariable regression model showed that having an LIV closer to the first lordotic vertebra was the only statistically significant predictor of DJF (OR 0.49, p = 0.013) and low LIV HUs did not reach statistical significance (OR 0.97, p = 0.09). CONCLUSIONS Patients with cervical deformity undergoing a 3CO are at higher risk for DJF with constructs terminating near the first lordotic vertebra. While LIV selection is complex and patient specific, choosing an LIV at least two levels above the first lordotic vertebra may help prevent DJF.

OBJECTIVE Management of locally invasive colorectal carcinoma at any stage currently involves surgical excision followed by chemoradiotherapy; however, the prognosis is poor, with a 5-year overall survival (OS) of only 5%. Failure to achieve gross-total resection is associated with poorer OS, and patients with residual tumor postresection (R1 or R2 resection) have a median OS of 7 months compared with 23 months in those who undergo resection with negative margins (R0 resection). For tumors that have invaded the sacrum, sacrectomy becomes necessary to achieve R0 resection. The objective of this study was to provide a descriptive multicenter account of resection for locally invasive colorectal carcinoma with sacral invasion, focusing on the association of tumor morphometry with surgical planning and perioperative outcomes. METHODS Demographic, comorbidity, clinical, tumor-specific, operative characteristic, and outcome data were collected on all patients who underwent resection of colorectal carcinoma with concurrent sacral resection between January 2005 and May 2022. Patients were grouped into those having undergone surgery for purely palliative intent, or those with resection with attempt at local control and dichotomized into level of osteotomy (either proximal or distal to the S2–3 level). RESULTS Twenty-two patients (median age 50.5 [IQR 43.3–60.0] years, 54.5% female) underwent sacrectomy for colorectal carcinoma. Operative records indicated intent for local control in 14 patients and palliative in the remaining 8 patients. Palliative surgical intent was based primarily on the presence of distant metastases. There was no significant difference in median local progression-free survival between patients undergoing osteotomy proximal to the S2–3 level and those undergoing osteotomy distal to the S2–3 level. CONCLUSIONS En bloc resection is believed to offer the best local control in patients with locally invasive colorectal carcinoma. The present descriptive series highlights outcomes of en bloc resection with partial or full sacrectomy in patients with tumors showing local extension into the sacrum. Complications are common, most often in the form of wound dehiscence or infection, and many patients require placement in a rehabilitation or intermediate-care facility upon discharge. However, for those with stage III (locally aggressive) disease, median OS exceeds 16 years, suggesting that such aggressive management with en bloc resection may be warranted in properly selected patients.

OBJECTIVE Blister aneurysms of the internal carotid artery (ICA) have high associated mortality rates and are challenging due to their friable wall and poorly defined neck. Microsurgical and endovascular treatment options have been suggested, including bypass of the parent vessel to exclude the aneurysm. The goal of this study was to evaluate the safety and efficacy of microsurgical versus endovascular interventions. Additionally, for patients treated with open surgery, the outcomes of bypass were compared to nonbypass techniques. METHODS Three databases were systematically queried for primary studies comparing microsurgery to endovascular therapy and assessing bypass versus nonbypass treatment modalities for blister aneurysms of the ICA. All relevant studies published between 2000 and 2023 were eligible for inclusion. All articles were screened against title and abstract by 2 authors, as were those eligible for full-text assessment. Ultimately, relevant data from all included studies were pooled for meta-analysis in which the Mantel-Haenszel method with random-effects modeling was used. RESULTS Among the 504 cases reported across 24 studies, 182 (35.1%) blister aneurysms of the ICA were surgically treated, whereas 337 (64.9%) involved endovascular treatment. There were 235 (46.6%) female patients in the cohort. Functional outcomes were comparable between groups, with 83% of surgically treated patients and 85% of endovascularly treated patients achieving a favorable outcome (p > 0.05). Among the 7 studies (178 patients) comparing bypass to nonbypass microsurgery, rates of postoperative bleeding, ischemic infarct, vasospasm, recurrence, favorable outcomes, and mortality were comparable for bypass (n = 54, 30.3%) and nonbypass groups (n = 124, 69.7%). CONCLUSIONS Blister aneurysms of the ICA are rare intracranial aneurysms that are difficult to treat with microsurgical and endovascular techniques. Considering only patients treated with open surgery, there appears to be no significant difference in complication profile or functional outcomes between patients undergoing bypass or alternative microsurgical techniques. However, it must be noted that the complex nature of bypass procedures means that much of the data granularity is lost on meta-analysis, suggesting that additional investigations comparing bypass to other open microsurgical techniques may be merited. Similarly, future studies should determine the limitations of dual antiplatelet therapy in endovascular treatment and the efficacy of different numbers and types of overlapping, flow-diverting devices.

BACKGROUND AND OBJECTIVES: Transforaminal lumbar interbody fusion (TLIF) allows for direct and indirect decompression and segmental lordosis in sagittal plane correction. This study compares the effectiveness of “Bullet” type and “Banana” type devices for sagittal plane correction. METHODS: Patients who underwent 1-level or 2-level TLIF for degenerative pathology at a single tertiary care center were identified. Details were extracted on demographics, interbody dimensions, and preoperative and postoperative lumbopelvic parameters from upright radiographs. Cages were categorized as “Bullet” or “Banana” type based on morphology and manufacturer description of optimal position. Univariable comparisons between levels treated with “Bullet” and “Banana” type interbodies were performed. Multivariable linear regression was performed to identify independent predictors of postoperative segmental lordosis and change in segmental lordosis. RESULTS: One hundred and ninety eight unique patients (median 66.6 years; [IQR 59.5, 73.7]; 56.6% female) were included with 241 levels treated, of which 114 (52.7%) were treated with “Banana” type interbodies and 127 (47.3%) with “Bullet” type. “Banana” type interbodies afforded both greater postoperative segmental lordosis (8.1 [6.2, 10.7] vs 7.5 [5.2, 9.6]; P = .048) and greater increase in segmental lordosis (3.3 [0.7, 7.0] vs 2.3 [0.1, 4.2]; P = .015). On multivariable linear regression, only preoperative segmental lordosis (β = 0.322 per degree; [0.244, 0.399]; P < .001), implant listed lordosis (β = 0.146 per degree; 95% CI [0.048, 0.244]; P = .004), preoperative pelvic incidence (0.072 per degree; [0.034, 0.111]; P < .001), and use of bilateral TLIF windows (β = 3.133; [1.213, 5.053]; P = .001) were predictive of postoperative segmental lordosis. CONCLUSION: The present analysis suggests that baseline lumbopelvic anatomy, interbody lordosis, and the use of bilateral TLIF windows are the most important predictors of postoperative segmental lordosis. Use of “Banana” vs “Bullet” type interbodies was not predictive of segmental lordosis achieved on immediate postoperative upright radiographs. Further work is merited to determine whether the 2 interbody types demonstrate differences regarding subsidence risk or maintenance of correction.