COVID-19 and influenza infections mediate distinct pulmonary cellular and transcriptomic changes.

SARS-CoV-2 infection can cause persistent respiratory sequelae. However, the underlying mechanisms remain unclear. Here we report that sub-lethally infected K18-human ACE2 mice show patchy pneumonia associated with histiocytic inflammation and collagen deposition at 21 and 45 days post infection (DPI). Transcriptomic analyses revealed that compared to influenza-infected mice, SARS-CoV-2-infected mice had reduced interferon-gamma/alpha responses at 4 DPI and failed to induce keratin 5 (Krt5) at 6 DPI in lung, a marker of nascent pulmonary progenitor cells. Histologically, influenza- but not SARS-CoV-2-infected mice showed extensive Krt5+ "pods" structure co-stained with stem cell markers Trp63/NGFR proliferated in the pulmonary consolidation area at both 7 and 14 DPI, with regression at 21 DPI. These Krt5+ "pods" structures were not observed in the lungs of SARS-CoV-2-infected humans or nonhuman primates. These results suggest that SARS-CoV-2 infection fails to induce nascent Krt5+ cell proliferation in consolidated regions, leading to incomplete repair of the injured lung.

Identification of Circulating Gene Expression Signatures of Intracranial Aneurysm in Peripheral Blood Mononuclear Cells.

Peripheral blood mononuclear cells (PBMCs) play an important role in the inflammation that accompanies intracranial aneurysm (IA) pathophysiology. We hypothesized that PBMCs have different transcriptional profiles in patients harboring IAs as compared to IA-free controls, which could be the basis for potential blood-based biomarkers for the disease. To test this, we isolated PBMC RNA from whole blood of 52 subjects (24 with IA, 28 without) and performed next-generation RNA sequencing to obtain their transcriptomes. In a randomly assigned discovery cohort of n = 39 patients, we performed differential expression analysis to define an IA-associated signature of 54 genes (q < 0.05 and an absolute fold-change ≥ 1.3). In the withheld validation dataset, these genes could delineate patients with IAs from controls, as the majority of them still had the same direction of expression difference. Bioinformatics analyses by gene ontology enrichment analysis and Ingenuity Pathway Analysis (IPA) demonstrated enrichment of structural regulation processes, intracellular signaling function, regulation of ion transport, and cell adhesion. IPA analysis showed that these processes were likely coordinated through NF-kB, cytokine signaling, growth factors, and TNF activity. Correlation analysis with aneurysm size and risk assessment metrics showed that 4/54 genes were associated with rupture risk. These findings highlight the potential to develop predictive biomarkers from PBMCs to identify patients harboring IAs.

Value of the Petromeatal Angle in Predicting Outcome of Translabyrinthine Resection of Vestibular Schwannomas.

BACKGROUND: Factors associated with extent of tumor resection (EOR) and facial nerve outcomes include tumor size, anterior extension of the tumor, patient age, and surgical approach. OBJECTIVE: To check whether preoperative measurement of the petromeatal (PMA), petroclival (PCA), and petrous-petrous (PPA) angles can help in predicting EOR, facial nerve outcome, and cerebrospinal fluid (CSF) leak occurrence in patients undergoing vestibular schwannoma (VS) surgery via the translabyrinthine approach (TLA). METHODS: A total of 75 patients were included in this retrospective study. Preoperative magnetic resonance imaging constructive interface in steady state and postcontrast T1-weighted sequences through the internal acoustic meatus were used to measure the PMA, PCA, and PPA. RESULTS: There was a statistically significant association between tumor size and EOR; every additional cm in tumor size decreases the odds of gross-total (GTR)/near-total (NTR) resection by 524% (P = .0000355).After controlling for tumor size, the logistic models revealed a significant effect of the angles on EOR. For example, in a patient with a 2-cm VS, every additional degree in PMA, PCA, and PPA increases the odds of GTR/NTR by 2.3% (P = .0000571), 4.05% (P = .0000397), and 0.37% (P = .0000438), respectively.After adjusting for tumor size, sex, and age, the effect of PMA on the occurrence of an immediate postoperative facial nerve deficit and CSF leak indicated a trend towards significance (P = .0581 and P = .0568, respectively). CONCLUSION: More obtuse petrous bone angles, namely PMA, PCA, and PPA, are good predictors of GTR or NTR in patients undergoing VS surgery via TLA and may be associated with better facial nerve outcomes and lower CSF leak occurrences.

Influence of Lumbar Stenosis Surgery on Sacroiliac Joint Pain-Long-Term Results.

OBJECTIVE: To investigate whether sacroiliac join (SIJ) pain can be secondary to walking with a flexed posture resulting from stenosis with neurogenic claudication, and resolves spontaneously after lumbar decompression. METHODS: A review of charts from January 1, 2014, through March 3, 2019, was performed to identify consecutive cases of adults 35 years of age or older with surgical spinal stenosis with neurogenic claudication as well as concomitant severe SIJ pain. Posture was considered flexed during walking if self-reported, confirmed by a close companion, or observed directly. SIJ pain was diagnosed clinically ± confirmatory injection. A 10-point visual analog scale was used to assess SIJ pain. The primary endpoint was SIJ pain improvement at a minimum of 24 months' follow-up. SIJ pain improvement at 3 months was used to assess the rate of improvement as a secondary endpoint. RESULTS: Ten patients (3 female) met entry criteria: 4 were treated with decompression alone; 6 with decompression and spinal fusion. Mean SIJ visual analog scale pain score improved by 6.9 ± 2.4 (8.7 ± 1.6-1.8 ± 2.2; P < 0.0005). Results were similar for 20 patients at the secondary endpoint of 3 months. CONCLUSIONS: Sacroiliac joint pain shows robust, rapid, reliable, and durable improvement following lumbar decompressive surgery. The addition of a spinal fusion also leads to a similar improvement in SIJ pain. This study demonstrates the importance of evaluating the specific source of low back pain in patients with stenosis, claudication, and SIJ pain so as to more effectively plan appropriate surgery.

Proximal fusion constructs in minimally invasive scoliosis surgery are successful without interbody or intertransverse fusion.

OBJECTIVE: Minimally invasive techniques are increasingly used in adult deformity surgery as surgeon familiarity improves and long-term data are published. Concerns raised in such cases include pseudarthrosis at levels where interbody grafts are not utilized. Few previous studies have specifically examined the thoracolumbar component of long surgical constructs, which is commonly instrumented without interbody or intertransverse fusion. METHODS: A retrospective analysis was performed on all patients who underwent hybrid minimally invasive deformity corrections in two academic spine centers over a 9-year period. Inclusion criteria were at least 2 rostral levels instrumented percutaneously, ranging from T8 to L1 as the upper end of the construct. Fusion assessment was made using CT when possible or radiography. Common radiographic parameters and clinical variables were assessed pre- and postoperatively. RESULTS: A total of 36 patients fit the inclusion criteria. Baseline characteristics included a 1:1.8 male/female ratio, average age of 65.7 years, and BMI of 30.2 kg/m2. Follow-up imaging was obtained at a mean of 35.7 months. The average number of levels fused was 7.5, with an average of 3.4 instrumented percutaneously between T8 and L1, representing a total of 120 rostral levels instrumented percutaneously. Fusion assessment was performed using CT in 69 levels and radiography in 51 levels. Among the 120 rostral levels instrumented percutaneously, robust fusion was noted in 25 (20.8%), with 53 (44.2%) exhibiting some evidence of fusion. Pseudarthrosis was noted in 2 rostral segments (1.7%). There were no instances of proximal hardware revision. Eight patients exhibited radiographic proximal junctional kyphosis (PJK; 22.2%), none of whom underwent surgical intervention. CONCLUSIONS: In the present series of adult patients with scoliosis undergoing thoracolumbar deformity correction, rostral segments instrumented percutaneously have a very low rate of pseudarthrosis, with radiographic evidence of bone fusion occurring in more than 60% of patients. The rate of PJK was acceptable and similar to other published series.

Retrospective Multicenter Assessment of Rod Fracture After Anterior Column Realignment in Minimally Invasive Adult Spinal Deformity Correction.

BACKGROUND: Anterior column realignment (ACR) was developed as a minimally invasive method for treating sagittal imbalance. However, rod fracture (RF) rates associated with ACR are not known. Our objective was to assess the rate of and risk factors for RF following ACR in deformity correction surgery. METHODS: We conducted a retrospective multicenter review of patients with adult spinal deformity (ASD) who underwent ACR for deformity correction. ASD was defined as coronal Cobb angle ≥20°, pelvic incidence-lumbar lordosis >10°, sagittal vertical axis ≥5 cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°. Inclusion criteria were ASD, age >18 years, use of ACR, and development of RF or full radiographs obtained at least 1 year after surgery that did not demonstrate RF. RESULTS: Ninety patients were identified, with mean follow-up of 2.3 ± 1.4 years (age, 64.1 ± 9.4; 54 [60%] women). The most common ACR location was L3/4 (42 cases; 47%). Mean fusion length was 7.5 ± 3.6 levels. Four (4.4%) of 90 patients developed RF within 12 months of surgery. RF occurred adjacent to ACR in all cases; RF was not associated with focal correction (P = 0.49), rod material (P = 0.8), degree of correction (P > 0.07), or interbody at L5/S1 (P = 0.06). RF was associated with longer fusion constructs in univariate (P = 0.002) and multivariate (P = 0.03) analyses. CONCLUSIONS: RF occurred in 4.4% of patients with ASD who underwent ACR with a minimum of 1-year follow-up. RF was not associated with focal correction but appears to be associated with global correction and extent of fixation.

Development of Proximal Junctional Kyphosis After Minimally Invasive Lateral Anterior Column Realignment for Adult Spinal Deformity.

BACKGROUND: Development of proximal junctional kyphosis (PJK) after correction of adult spinal deformity (ASD) undermines sagittal alignment. Minimally invasive anterior column realignment (ACR) is a powerful tool for correction of ASD; however, long-term PJK rates are unknown. OBJECTIVE: To characterize PJK after utilization of ACR in ASD correction. METHODS: A retrospective multi-institution cohort analysis per STROBE criteria was conducted of all patients who underwent lateral lumbar interbody fusion (LLIF) or ACR for ASD from 2010 to 2015. All patients obtained preoperative and follow-up upright radiographs, assessing spinal alignment and development of PJK. Patients without proper imaging or minimum 1-yr follow-up were excluded. RESULTS: A total of 73 of 112 patients who underwent either LLIF or ACR for ASD met inclusion criteria. Mean follow-up was 22.8 mo. There was significant improvement of all spinopelvic parameters. Overall, PJK and proximal junctional failure (PJF) rates were 20.5% and 11%, respectively. The incidence of PJK increased with greater corrective surgery (0% LLIF, 30% ACR, 42.9% ACR + posterior column osteotomy (PCO); P < .001). PJF rates increased (0% LLIF, 11% ACR, 40% ACR + PCO; P = .005). Risk factors included location of the upper-instrumented vertebra at T10-L1 vs L2-L4 (P = .007), age (P = .029), severity of ASD, and overcorrection of sagittal imbalance. CONCLUSION: The incidence of PJK after minimally invasive ACR is slightly lower than reported after open surgery but greater than in LLIF only and increases with PCO utilization. The PJK rate increases when crossing the TL junction, sagittal imbalance severity, and overcorrection. Elderly patients are at an increased risk, suggesting need for age appropriate correction goals.

Morphometric Analysis of Lumbar Intervertebral Disc Height: An Imaging Study.

BACKGROUND: Little published data exist regarding normal values of disc height. Current literature relies on plain radiographs making accurate measurements of individual lumbar disc height difficult. OBJECTIVE: We seek to establish normal values for lumbar intervertebral discs in different age groups using computed tomography scans in healthy individuals. METHODS: Two hundred forty anonymized abdominal computed tomography scans (131 women) were prospectively collected once institutional review board approval was obtained. Individuals with spinal pathologies were excluded. Disc height measurements were obtained at the anterior edge, center, and posterior edge of each vertebra in the midsagittal plane, averaged, and compared against age and sex. RESULTS: Average age was 45 (14-83) years for women and 48 (14-89) years for men. Average lumbar disc height was 5.6 ± 1.1 mm for men and 4.8 ± 0.8 mm for women at T12/L1, 6.9 ± 1.3 mm for men and 5.8 ± 0.9 mm for women at L1/2, 8.1 ± 1.4 mm for men and 6.9 ± 1.1 mm for women at L2/3, 8.7 ± 1.5 mm for men and 7.6 ± 1.2 mm for women at L3/4, 9.2 ± 1.6 mm for men and 8.5 ± 1.6 mm for women at L4/5, and 8.8 ± 1.6 mm for men and 8.6 ± 1.8 mm for women at L5/S1. Disc height was significantly smaller for women than men (P < 0.001), except at L5/S1. CONCLUSIONS: Variation in disc height is determined much more by sex than age. The maximum height of the interbody space in the adult lumbar spine was at the L4/5 level (8.9 ± 1.7 mm [men], 8.6 ± 1.8 mm [women]). Based on our findings, >10 mm cage height will result in supraphysiologic interbody space restoration and potentially predispose to complications.

Minimally Invasive Lateral Transpsoas Interbody Fusion at the L4/5 Level: A Review of 61 Consecutive Cases.

BACKGROUND: Reported complication rates for minimally invasive lateral transpsoas interbody fusion (MIS-LIF) vary widely. The risk of lumbar plexus injury is particularly concerning at the L4-5 disc space. We report our experience with MIS-LIF at L4-5, and discuss the risk profile of transpsoas approaches at this level. OBJECTIVE: To evaluate safety of MIS-LIF at the L4/5 level. METHODS: This was a retrospective, IRB-approved cohort study performed at a single institution from 2011 to 2016. Patients who underwent MIS-LIF at L4-5 were included. Patients with multilevel fusions were excluded. We analyzed postoperative sensory and motor deficits, the date of resolution, health-related quality-of-life scores, and rate of fusion. RESULTS: Over a 5-yr period, 303 patients underwent MIS-LIF at our institution. Sixty-one patients had surgery only at the L4-5 level (20.1%). Twelve of these patients (19.6%) had postoperative neurological deficits including 2 motor deficits (2/61 = 3.2%) and 11/61 (18%) sensory deficits. At 12-mo follow-up, 3 of the deficits persisted for a long-term complication rate of 3/61 (4.9%), motor complication 2/61 (3.2%). Hospital stay and follow-up averaged 2.1 d and 15 mo. Average Oswestry Disability Index improved from 51.1 to 31.1 (P < .00001). Visual Analog Scale (VAS) improved from 7.4 to 3.9 (P < .016). There were no reoperations secondary to hardware failure or pseudoarthrosis. Fusion rate was 89% at 12 mo. CONCLUSION: MIS-LIF is a safe and effective approach for interbody fusion at L4-5 with low rate of lumbar plexus injury. Most immediate postoperative deficits will resolve over time.

Minimally invasive anterior and lateral transpsoas approaches for closed reduction of grade II spondylolisthesis: initial clinical and radiographic experience.

OBJECTIVE Minimally invasive anterior and lateral approaches to the lumbar spine are increasingly used to treat and reduce grade I spondylolisthesis, but concerns still exist for their usage in the management of higher-grade lesions. The authors report their experience with this strategy for grade II spondylolisthesis in a single-surgeon case series and provide early clinical and radiographic outcomes. METHODS A retrospective review of a single surgeon's cases between 2012 and 2016 identified all patients with a Meyerding grade II lumbar spondylolisthesis who underwent minimally invasive lateral lumbar interbody fusion (LLIF) or anterior lumbar interbody fusion (ALIF) targeting the slipped level. Demographic, clinical, and radiographic data were collected and analyzed. Changes in radiographic measurements, Oswestry Disability Index (ODI), and visual analog scale (VAS) scores were compared using the paired t-test and Wilcoxon signed rank test for continuous and ordinal variables, respectively. RESULTS The average operative time was 199.1 minutes (with 60.6 ml of estimated blood loss) for LLIFs and 282.1 minutes (with 106.3 ml of estimated blood loss), for ALIFs. Three LLIF patients had transient unilateral anterior thigh numbness during the 1st week after surgery, and 1 ALIF patient had transient dorsiflexion weakness, which was resolved at postoperative week 1. The mean follow-up time was 17.6 months (SD 12.5 months) for LLIF patients and 10 months (SD 3.1 months) for ALIF patients. Complete reduction of the spondylolisthesis was achieved in 12 LLIF patients (75.0%) and 7 ALIF patients (87.5%). Across both procedures, there was an increase in both the segmental lordosis (LLIF 5.6°, p = 0.002; ALIF 15.0°, p = 0.002) and overall lumbar lordosis (LLIF 2.9°, p = 0.151; ALIF 5.1°, p = 0.006) after surgery. Statistically significant decreases in the mean VAS and the mean ODI measurements were seen in both treatment groups. The VAS and ODI scores fell by a mean value of 3.9 (p = 0.002) and 19.8 (p = 0.001), respectively, for LLIF patients and 3.8 (p = 0.02) and 21.0 (p = 0.03), respectively, for ALIF patients at last follow-up. CONCLUSIONS Early clinical and radiographic results from using minimally invasive LLIF and ALIF approaches to treat grade II spondylolisthesis appear to be good, with low operative blood loss and no neurological deficits. Complete reduction of the spondylolisthesis is frequently possible with a statistically significant reduction in pain scores.

Indirect decompression and reduction of lumbar spondylolisthesis does not result in higher rates of immediate and long term complications.

Nerve root decompression and spondylolisthesis reduction is typically reserved for open surgery. MIS techniques have been thought to be associated with higher rates of neurological complications. This study aims to report acute and chronic neurologic complications encountered with MIS surgery for spondylolisthesis, specifically, the incidence of nerve root injury and clinical and radiographic outcomes. A retrospective review of 269 patients who underwent MIS LIF or ALIF treatment for lumbar degenerative or isthmic grade 1 or 2 spondylolisthesis was conducted. Immediate and long-term complication rates were the primary outcome. Only patients who had symptomatic anterolisthesis and 2-year outcome data were included in the study. 52 patients met inclusion criteria with 54 lumbar spondylolisthesis levels treated. Five patients (9.6%) experienced postoperative anterior thigh numbness, which completely resolved within 3months. There were no permanent neurologic deficits; however, 2 patients (3.8%) suffered a transient foot weakness that resolved with physical therapy by 3months follow-up. There was one incidence of wound breakdown that required revision and one incidence of L5/S1 endplate/sacral promontory fracture and relisthesis 3months postoperatively. Overall fusion rate was 98% at 6months. Indirect decompression and closed anatomical reduction for treatment of low-grade spondylolisthesis using ALIF and LIF with posterior percutaneous fixation was not associated with an increased risk of neurologic deficit. This study suggests that this technique is safe, reproducible, durable, and provides adequate fusion rates.

Effects of intradiscal vacuum phenomenon on surgical outcome of lateral interbody fusion for degenerative lumbar disease.

OBJECTIVE The authors investigated whether the presence of intradiscal vacuum phenomenon (IVP) results in greater correction of disc height and restoration of segmental lordosis (SL). METHODS A retrospective chart review was performed on every patient at the University of South Florida's Department of Neurosurgery treated with lateral lumbar interbody fusion between 2011 and 2015. From these charts, preoperative plain radiographs and CT images were reviewed for the presence of IVP. Preoperative and postoperative posterior disc height (PDH), anterior disc height (ADH), and SL were measured at disc levels with IVP and compared with those at disc levels without IVP using the t-test. Linear regression was used to evaluate the factors that predict changes in PDH, ADH, and SL. RESULTS One hundred forty patients with 247 disc levels between L-1 and L-5 were treated with lateral lumbar interbody fusion. Among all disc levels treated, the mean PDH increased from 3.69 to 6.66 mm (p = 0.011), the mean ADH increased from 5.45 to 11.53 mm (p < 0.001), and the mean SL increased from 9.59° to 14.55° (p < 0.001). Significantly increased PDH was associated with the presence of IVP, addition of pedicle screws, and lack of cage subsidence; significantly increased ADH was associated with the presence of IVP, anterior longitudinal ligament (ALL) release, addition of pedicle screws, and lack of subsidence; and significantly increased SL was associated with the presence of IVP and ALL release. CONCLUSIONS IVP in patients with degenerative spinal disease remains grossly underreported. The data from the present study suggest that the presence of IVP results in increased restoration of disc height and SL.

Anterior Longitudinal Ligament Release From the Minimally Invasive Lateral Retroperitoneal Transpsoas Approach: Technical Note.

BACKGROUND: The technique for minimally invasive anterior longitudinal ligament release is a major advancement in lateral access surgery. This method provides hypermobility of lumbar segments to allow for aggressive lordosis restoration while maintaining the benefits of indirect decompression and minimally invasive access. OBJECTIVE: To provide video demonstration of the lateral retroperitoneal transpsoas approach with anterior longitudinal ligament sectioning. METHODS: A detailed surgical technique of the minimally invasive anterior column release is described and illustrated in an elderly patient with adult spinal deformity and low back pain (visual analog scale, 8 of 10) refractory to conservative measures. The 3-foot standing radiographs demonstrated a lumbar lordosis of 54.4°, pelvic incidence of 63.7°, and pelvic tilt of 17.5°. Computed tomography and magnetic resonance imaging showed generalized lumbar spondylosis and degenerative disc changes from L2 to L5. RESULTS: The patient underwent a multilevel minimally invasive deformity correction with an anterior longitudinal ligament release at the L3/L4 level through the lateral retroperitoneal transpsoas approach. Lumbar lordosis increased from 54.4° to 77° with a global improvement in sagittal vertical axis from 4.37 cm to 0 cm. Total blood loss was less than 25 mL, and there were no major neurological or vascular complications. CONCLUSION: The anterior longitudinal ligament release using the minimally invasive lateral approach allows for deformity correction without the morbidity and blood loss encountered by traditional open posterior approaches. However, the risk of major vascular/visceral complication warrants only experts in minimally invasive lateral surgery to attempt this technique.

Complications and neurological deficits following minimally invasive anterior column release for adult spinal deformity: a retrospective study.

BACKGROUND: Minimally invasive techniques have become increasing popular and are expanding into deformity surgery. The lateral retroperitoneal transpsoas anterior column release (ACR) is a newer minimally invasive alternative to posterior osteotomy techniques for correcting and promoting global spinal alignment. This procedure attempts to avoid the potential complications associated with conventional osteotomies, but has its own subset of unique complications to be discussed in depth. METHODS: A retrospective review was performed in all patients who underwent the minimally invasive (MIS) ACR procedure from 2010 to present at our institution. All perioperative and postoperative complications were recorded by an independent reviewer. Demographics, spinopelvic parameters, and operative data were collected. The primary etiologic diagnosis was adult spinal deformity. Spinopelvic parameters were measured based on standing 36-inch scoliosis films. RESULTS: Thirty-one patients underwent a total of 47 MIS-ACRs. The mean age of the cohort was 62. Mean follow up was 12 months (range 3-38 months). The average change from in lumbar lordosis (LL) was 17.6°, in pelvic tilt was 4.3°, coronal Cobb was 13.9 and in SVA was 3.8 cm. Of the 47 MIS-ACR procedures, there were 9 (9/47, 19 %) major complications related to the ACR. Iliopsoas weakness was seen in eight patients and retrograde ejaculation in one patient. Only one patient remained with mild motor deficit at the most recent follow-up. No revision surgeries were required for the anterolateral approach. There was no vascular, visceral, or infectious complications associated with the MIS-ACR. CONCLUSION: The MIS-ACR is one of the most technically demanding procedures performed from the lateral transpsoas approach. This procedure has the advantage of maintaining and improving spinal global alignment while minimizing blood loss and excessive tissue dissection. It comes with its own unique set of potentially catastrophic complications and should only be performed by surgeons proficient in both deformity correction and the lateral approach.

Stand-alone minimally invasive lateral lumbar interbody fusion: multicenter clinical outcomes.

Stand-alone minimally invasive lateral transpsoas interbody fusion (MIS-LIF), without posterior instrumentation, is feasible because the technique does not necessitate the disruption of the stabilizing elements. The objectives of this study are to evaluate the efficacy and clinical outcomes of patients who underwent stand-alone lateral interbody fusion. A multicenter chart review was conducted to identify patients who underwent stand-alone MIS-LIF between 2008 and 2012. Patients were classified by spinal pathology (degenerative disc disease [DDD], spondylolisthesis [SL] and adult degenerative scoliosis [ADS]). Routine clinical follow-up was scheduled at 3, 6, and12 months. Outcome measures included hospital length of stay, fusion rates, neurologic complications, integrity of construct and clinical outcome questionnaires (Visual Analog Scale [VAS] and Oswestry Disability Index [ODI]). A total of 59 patients met the inclusion criteria. The average age was 60 years (range 31-86 years). Spinal pathologies treated were DDD in 37 (63%), SL in four (7%) and ADS in 18 (30%) patients. Fusion rate was 93% of patients (95% of levels) at 12 months. Two patients required re-operation. Mean hospital stay and follow-up were 3.3days (range 1-10) and 14.6 months, respectively. The mean preoperative VAS and ODI were 69.1 and 51.8, respectively. VAS improved to 37.8 (p<0.0005). ODI improved to 31.8 (p<0.0005). Seventy percent of patients had grade 0 subsidence while 30% had grade I and grade II subsidence. Stand-alone MIS-LIF is viable option in a carefully selected patient population for both single and multilevel disease and shows significant improvement in health related quality of life.

Percutaneous Minimally Invasive (MIS) Guide Wire-less Self-Tapping Pedicle Screw Placement in the Thoracic and Lumbar Spine: Safety and Initial Clinical Experience: Technical Note.

BACKGROUND: Multiple methods for minimally invasive (MIS) thoracic and lumbar pedicle screw placement exist. The guide wire is almost universally used for most insertion techniques; however, its use is not without complication and potentially prolongs surgical procedures. OBJECTIVE: To evaluate the safety of percutaneous MIS guide wire-less pedicle screw placement in the thoracic and lumbar spine at a single institution over a 3-year experience. METHODS: Forty-one patients who underwent posterior instrumentation with 110 transpedicular MIS thoracic and lumbar screws by a single surgeon from 2011 to 2014 were analyzed. The mean age was 63 years at the time of surgery. Etiological diagnoses were adult spinal deformity, trauma, spondylosis/spondylolisthesis, and other spinal diseases. Pedicle screws were inserted with the use of a guide wire-free technique in which anatomy-specific entry sites and fluoroscopic landmarks were used to guide the surgeon. A square, sharp-tipped pedicle screw was carefully advanced under biplanar fluoroscopic image (anteroposterior and lateral) down the pedicle into the body. No tapping or any type of electromonitoring was performed. An independent spine surgeon using medical records and thoracic/lumbar computed tomography taken during the postoperative period reviewed all patients. RESULTS: The number of the screws inserted at each level was as follows: total, 110; thoracic, 30; and lumbar, 80. All screws were evaluated by computed tomography to assess screw position. Seven screws (6.3%) were inserted with moderate cortical perforation, including 3 screws (2.7%) that violated the medial wall. There were no neurological, vascular, or visceral complications with up to 3 years of follow-up. CONCLUSION: The percutaneous MIS guide wire-less technique of lumbar and thoracic pedicle screw placement performed using a biplanar fluoroscopic guidance in a stepwise, consistent manner is an accurate, safe, and reproducible method of insertion to treat a variety of spinal disorders.

Management of sagittal balance in adult spinal deformity with minimally invasive anterolateral lumbar interbody fusion: a preliminary radiographic study.

OBJECT: Minimally invasive (MI) fusion and instrumentation techniques are playing a new role in the treatment of adult spinal deformity. The open pedicle subtraction osteotomy (PSO) and Smith-Petersen osteotomy (SPO) are proven segmental methods for improving regional lordosis and global sagittal parameters. Recently the MI anterior column release (ACR) was introduced as a segmental method for treating sagittal imbalance. There is a paucity of data in the literature evaluating the alternatives to PSO and SPO for sagittal balance correction. Thus, the authors conducted a preliminary retrospective radiographic review of prospectively collected data from 2009 to 2012 at a single institution. The objectives of this study were to: 1) investigate the radiographic effect of MI-ACR on spinopelvic parameters, 2) compare the radiographic effect of MI-ACR with PSO and SPO for treatment of adult spinal deformity, and 3) investigate the radiographic effect of percutaneous posterior spinal instrumentation on spinopelvic parameters when combined with MI transpsoas lateral interbody fusion (LIF) for adult spinal deformity. METHODS: Patient demographics and radiographic data were collected for 36 patients (9 patients who underwent MI-ACR and 27 patients who did not undergo MI-ACR). Patients included in the study were those who had undergone at least a 2-level MI-LIF procedure; adequate preoperative and postoperative 36-inch radiographs of the scoliotic curvature; a separate second-stage procedure for the placement of posterior spinal instrumentation; and a diagnosis of degenerative scoliosis (coronal Cobb angle > 10° and/or sagittal vertebral axis > 5 cm). Statistical analysis was performed for normality and significance testing. RESULTS: Percutaneous transpedicular spinal instrumentation did not significantly alter any of the spinopelvic parameters in either the ACR group or the non-ACR group. Lateral MI-LIF alone significantly improved coronal Cobb angle by 16°, and the fractional curve significantly improved in a subgroup treated with L5-S1 transforaminal lumbar interbody fusion. Fifteen ACRs were performed in 9 patients and resulted in significant coronal Cobb angle correction, lumbar lordosis correction of 16.5°, and sagittal vertebral axis correction of 4.8 cm per patient. Segmental analysis revealed a 12° gain in segmental lumbar lordosis and a 3.1-cm correction of the sagittal vertebral axis per ACR level treated. CONCLUSIONS: The lateral MI-LIF with ACR has the ability to powerfully restore lumbar lordosis and correct sagittal imbalance. This segmental MI surgical technique boasts equivalence to SPO correction of these global radiographic parameters while simultaneously creating additional disc height and correcting coronal imbalance. Addition of posterior percutaneous instrumentation without in situ manipulation or overcorrection does not alter radiographic parameters when combined with the lateral MI-LIF.

Minimally invasive surgical techniques in adult degenerative spinal deformity: a systematic review.

BACKGROUND: Minimally invasive surgery (MIS) approaches have the potential to reduce procedure-related morbidity when compared with traditional approaches. However, the magnitude of radiographic correction and degree of clinical improvement with MIS techniques for adult spinal deformity remain undefined. QUESTION/PURPOSES: In this systematic review, we sought to determine whether MIS approaches to adult spinal deformity correction (1) improve pain and function; (2) reliably correct deformity and result in fusion; and (3) are safe with respect to surgical and medical complications. METHODS: A systematic review of PubMed and Medline databases was performed for published articles from 1950 to August 2013. A total of 1053 papers were identified. Thirteen papers were selected based on prespecified criteria, including a total of 262 patients. Studies with limited short-term followup (mean, 12.1 months; range, 1.5-39 months) were included to capture early complications. All of the papers included in the review constituted Level IV evidence. Patient age ranged from 20 to 86 years with a mean of 65.8 years. Inclusion and exclusion criteria were variable, but all required at minimum a diagnosis of adult degenerative scoliosis. RESULTS: Four studies demonstrated improvement in leg/back visual analog scale, three demonstrated improvement in the Oswestry Disability Index, one demonstrated improvement in treatment intensity scale, and one improvement in SF-36. Reported fusion rates ranged from 71.4% to 100% 1 year postoperatively, but only two of 13 papers relied consistently on CT scan to assess fusion, and, interestingly, only four of 10 studies reporting radiographic results on deformity correction found the procedures effective in correcting deformity. There were 115 complications reported among the 258 patients (46%), including 37 neurological complications (14%). CONCLUSIONS: The literature on these techniques is scanty; only two of the 13 studies that met inclusion criteria were considered high quality; CT scans were not generally used to evaluate fusion, deformity correction was inconsistent, and complication rates were high. Future directions for analysis must include comparative trials, longer-term followup, and consistent use of CT scans to assess for fusion to determine the role of MIS techniques for adult spinal deformity.

Minimally invasive lateral approach for adult degenerative scoliosis: lessons learned.

OBJECT: Lateral minimally invasive thoracolumbar instrumentation techniques are playing an increasing role in the treatment of adult degenerative scoliosis. However, there is a paucity of data in determining the ideal candidate for a lateral versus a traditional approach, and versus a hybrid construct. The objective of this study is to present a method for utilizing the lateral minimally invasive surgery (MIS) approach for adult spinal deformity, provide clinical outcomes to validate our experience, and determine the limitations of lateral MIS for adult degenerative scoliosis correction. METHODS: Radiographic and clinical data were collected for patients who underwent surgical correction of adult degenerative scoliosis between 2007 and 2012. Patients were retrospectively classified by degree of deformity based on coronal Cobb angle, central sacral vertical line (CSVL), pelvic incidence, lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), presence of comorbidities, bone quality, and curve flexibility. Patients were placed into 1 of 3 groups according to the severity of deformity: "green" (mild), "yellow" (moderate), and "red" (severe). Clinical outcomes were determined by a visual analog scale (VAS) and the Oswestry Disability Index (ODI). RESULTS: Of 256 patients with adult degenerative scoliosis, 174 underwent a variant of the lateral approach. Of these 174 patients, 27 fit the strict inclusion/exclusion criteria (n = 9 in each of the 3 groups). Surgery in 17 patients was dictated by their category, and 10 were treated with surgery outside of their classification. The average age was 61 years old and the mean follow-up duration was 17 months. The green and yellow groups experienced a reduction in coronal Cobb angle (12° and 11°, respectively), and slight changes in CSVL, SVA, and PT, and LL. In the green group, the VAS and ODI improved by 35 and 17 points, respectively, while in the yellow group they improved by 36 and 33 points, respectively. The red subgroup showed a 22° decrease in coronal Cobb angle, 15° increase in LL, and slight changes in PT and SVA. Three patients placed in the yellow subgroup had "green" surgery, and experienced a coronal Cobb angle and LL decrease by 17° and 10°, respectively, and an SVA and PT increase by 1.3 cm and 5°, respectively. Seven patients placed in the red group who underwent "yellow" or "green" surgery had a reduction in coronal Cobb angle of 16°, CSVL of 0.1 cm, SVA of 2.8 cm, PT of 4°, VAS of 28 points, and ODI of 12 points; lumbar lordosis increased by 15°. Perioperative complications included 1 wound infection, transient postoperative thigh numbness in 2 cases, and transient groin pain in 1 patient. CONCLUSIONS: Careful patient selection is important for the application of lateral minimally invasive techniques for adult degenerative scoliosis. Isolated lateral interbody fusion with or without instrumentation is suitable for patients with preserved spinopelvic harmony. Moderate sagittal deformity (compensated with pelvic retroversion) may be addressed with advanced derivatives of the lateral approach, such as releasing the anterior longitudinal ligament. For patients with severe deformity, the lateral approach may be used for anterior column support and to augment arthrodesis.

CMOS-integrated geometrically tunable optical filters.

We present a method for producing monolithically integrated complementary metal-oxide-semiconductor (CMOS) optical filters with different and customer-specific responses. The filters are constituted by a Fabry-Perot resonator formed by two Bragg mirrors separated by a patterned cavity. The filter response can be tuned by changing the geometric parameters of the patterning, and consequently the cavity effective refractive index. In this way, many different filters can be produced at once on a single chip, allowing multichanneling. The filter has been designed, produced, and characterized. The results for a chip with 24 filters are presented.