Feasibility and outcome of stand-alone trans-articular screw fixation in atlantoaxial instability in children less than 8 years of age.

PURPOSE: To study the feasibility and outcome of stand-alone trans-articular screw (TAS) fixation for atlantoaxial instability (AAI) in children less than 8 years of age. METHODS: This prospective study was conducted between 2009 and 2014. Thirteen children suffering from AAI were operated for a TAS fixation. Feasibility of TAS fixation was assessed on CT scan and a screw diameter was chosen based on C2 isthmus diameter. Demographic data collected included the etiology for AAI, age, and sex. Intra-operative data recorded was the duration of surgery, blood loss, vertebral artery injury or any adverse event. Radiological evaluation included pre- and post-operative atlantodens interval (ADI) and space available for cord (SAC) and fusion was evaluated at 3, 6, 12 and 24 months. Statistical analysis was done using SPSS software and statistical significance was set at p < 0.05. RESULTS: The mean age of the final study group was 6.1 ± 1.5 years, with nine males and four females. Mean isthmus diameter on the left and right side was 3.3 ± 0.3 and 3.2 ± 0.2 mm, respectively. Five patients had an isthmus diameter of < 3.2 mm and a 2.7 mm Herbert screw was used in them and in nine patients, a CCS of 3.2 mm was used. Mean pre- and post-op ADI and SAC improved from 5.5 ± 0.8 to 3.1 ± 0.1 mm, respectively, and 9.8 ± 2.8 to 14 ± 0.6 mm, respectively. Fusion was seen in all patients. CONCLUSIONS: Stand-alone TAS with morselized allograft is safe, feasible and successful in managing AAI in children below 8 years of age. These slides can be retrieved under Electronic Supplementary Material.

Degenerative Spondylolisthesis: When to Fuse and When Not to? A New Scoring System.

STUDY DESIGN: A prospective cohort. OBJECTIVE: The objective of this study was to develop a scoring system for lumbar degenerative spondylolisthesis (LDS) that would guide decision-making. BACKGROUND: The management protocol for LDS has been under debate, with no guidelines. Most studies oversimplify LDS as a homogenous entity. MATERIALS AND METHODS: A retrospective analysis of 131 patients who underwent surgery for LDS between July 2007 and October 2011 with a minimum follow-up of 3 years was carried out on the basis of clinical, radiologic, and technical factors. A scoring system was conceptualized. Clinical: back pain score-2, age younger than 70 years-1, high-demand activity-1. Radiologic: segmental kyphosis-1.5, segmental dynamic translation-1, disk height >50% of adjacent level-1, facet effusion-1, sagittal facet-orientation-1. Technical: feasibility to decompress without causing instability-1.5. Its reliability was ascertained by a univariate analysis. The benchmark was set at 5.5 according to the Youden Index. This was followed by a prospective study for reliability analysis between November 2011 and January 2017 of 52 patients who underwent stand-alone decompression in LDS with a minimum follow-up of 24 months. Outcomes were evaluated using the Oswestry Disability Index and the Visual Analog Scale. Interobserver variability was determined. None of the patients in the retrospective or prospective group had undergone any lumbar surgery previously. RESULTS: The mean Oswestry Disability Index and Visual Analog Scale of both the groups in the retrospective and the stand-alone decompression groups in prospective studies showed significant improvement. The interobserver reliability was high, with a κ value of 0.847. CONCLUSIONS: The proposed scoring system helps view LDS as a heterogenous condition and assists in tailoring treatment for individual patients. For a select subgroup of patients with LDS, minimally invasive decompression (unilateral laminotomy and bilateral decompression using a minimally invasive surgery tubular retractor system) without fusion is adequate. LEVEL OF EVIDENCE: Level III.

Risk factor analysis of postoperative kyphotic change in subaxial cervical alignment after upper cervical fixation.

OBJECTIVELittle is known about the risk factors for postoperative subaxial cervical kyphosis following craniovertebral junction (CVJ) fixation. The object of this study was to evaluate postoperative changes in cervical alignment and to identify the risk factors for postoperative kyphotic change in the subaxial cervical spine after CVJ fixation.METHODSOne hundred fifteen patients were retrospectively analyzed for postoperative subaxial kyphosis after CVJ fixation. Relations between subaxial kyphosis and radiological risk factors, including segmental angles and ranges of motion (ROMs) at C0-1, C1-2, and C2-7, and clinical factors, such as age, sex, etiology, occipital fixation, extensor muscle resection at C2, additional C1-2 posterior wiring, and subaxial laminoplasty, were investigated. Univariate and multivariate logistic regression analyses were conducted to identify the risk factors for postoperative kyphotic changes in the subaxial cervical spine.RESULTSThe C2-7 angle change was more than -10° in 30 (26.1%) of the 115 patients. Risk factor analysis showed CVJ fixation combined with subaxial laminoplasty (OR 9.336, 95% CI 1.484-58.734, p = 0.017) and a small ROM at the C0-1 segment (OR 0.836, 95% CI 0.757-0.923, p < 0.01) were related to postoperative subaxial kyphotic change. On the other hand, age, sex, resection of the C2 extensor muscle, rheumatoid arthritis, additional C1-2 posterior wiring, and postoperative segmental angles were not risk factors for postoperative subaxial kyphosisCONCLUSIONSSubaxial alignment change is not uncommon after CVJ fixation. Muscle detachment at the C2 spinous process was not a risk factor of kyphotic change. The study findings suggest that a small ROM at the C0-1 segment with or without occipital fixation and combined subaxial laminoplasty are risk factors for subaxial kyphotic change.

Minimally Invasive Microscope-Assisted Stand-Alone Transarticular Screw Fixation without Gallie Supplementation in the Management of Mobile Atlantoaxial Instability.

STUDY DESIGN: Retrospective study. PURPOSE: To evaluate the clinico-radiological efficacy of stand-alone minimally invasive transarticular screw (MIS-TAS) fixation without supplemental Gallie fixation in the management of mobile C1-C2 instability. OVERVIEW OF LITERATURE: Data evaluating the efficacy and feasibility of MIS-TAS in the literature is scanty. METHODS: Patients with mobile atlantoaxial instability and >2 years follow-up were included and managed by stand-alone TAS fixation using the Magerl technique and morselized allograft without additional fixation. Patient demographics and intra-operative parameters were noted. Clinical parameters (Visual Analog Scale [VAS] and Oswestry Disability Index [ODI]), neurology (modified Japanese Orthopaedic Association [mJOA]), and radiological factors (anterior atlanto-dens interval and space available for cord) were evaluated pre and postoperatively. Computed tomography (CT) was performed in patients who did not show interspinous fusion on X-ray at 1 year, to verify intra-articular fusion. Statistical analysis was performed using IBM SPSS ver. 20.0 (IBM Corp., Armonk, NY, USA); the Student t -test and analysis of variance were used to assess statistical significance (p <0.05). RESULTS: A total of 82 consecutive cases (three males, one female; mean age, 36.26±5.78 years) were evaluated. In total, 163 TASs were placed. Significant improvement was noticed in clinical (mean preoperative VAS=7.2±2.19, postoperative VAS=3.3±1.12; mean preoperative ODI=78.3±4.83, postoperative ODI=34.05±3.26) and neurological features (mean preoperative mJOA=14.73±2.68, postoperative mJOA=17.5±2.21). Radiological evidence of fusion was noted in 97.5% cases at final follow-up. Seventeen patients were found to have no interspinous fusions upon X-rays, but CT revealed facet fusion in all patients except in two. Inadvertent vertebral artery injury was noted in three cases. CONCLUSIONS: Stand-alone TAS fixation with morselized allograft provides excellent radiological and clinical outcomes. The addition of a supplementary tension band and structural graft are not essential. This provides the opportunity to avoid the complications associated with graft harvesting and wiring.

Comparative Prospective Study Reporting Intraoperative Parameters, Pedicle Screw Perforation, and Radiation Exposure in Navigation-Guided versus Non-navigated Fluoroscopy-Assisted Minimal Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Prospective cohort study. PURPOSE: To compare intraoperative parameters, radiation exposure, and pedicle screw perforation rate in navigation-guided versus non-navigated fluoroscopy-assisted minimal invasive transforaminal lumbar interbody fusion (MIS TLIF). OVERVIEW OF LITERATURE: The poor reliability of fluoroscopy-guided instrumentation and growing concerns about radiation exposure have led to the development of navigation-guided instrumentation techniques in MIS TLIF. The literature evaluating the efficacy of navigation-guided MIS TLIF is scant. METHODS: Eighty-seven patients underwent navigation- or fluoroscopy-guided MIS TLIF for symptomatic lumbar/lumbosacral spondylolisthesis. Demographics, intraoperative parameters (surgical time, blood loss), and radiation exposure (sec/mGy/Gy.cm2 noted from C-arm for comparison only) were recorded. Computed tomography was performed in patients in the navigation and non-navigation groups at postoperative 12 months and reviewed by an independent observer to assess the accuracy of screw placement, perforation incidence, location, grade (Mirza), and critical versus non-critical neurological implications. RESULTS: Twenty-seven patients (male/female, 11/16; L4-L5/L5-S1, 9/18) were operated with navigation-guided MIS TLIF, whereas 60 (male/female, 25/35; L4-L5/L5-S1, 26/34) with conventional fluoroscopy-guided MIS TILF. The use of navigation resulted in reduced fluoroscopy usage (dose area product, 0.47 Gy.cm2 versus 2.93 Gy.cm2), radiation exposure (1.68 mGy versus 10.97 mGy), and fluoroscopy time (46.5 seconds versus 119.08 seconds), with p-values of <0.001. Furthermore, 96.29% (104/108) of pedicle screws in the navigation group were accurately placed (grade 0) (4 breaches, all grade I) compared with 91.67% (220/240) in the non-navigation group (20 breaches, 16 grade I+4 grade II; p=0.114). None of the breaches resulted in a corresponding neurological deficit or required revision. CONCLUSIONS: Navigation guidance in MIS TLIF reduced radiation exposure, but the perforation status was not statistically different than that for the fluoroscopy-based technique. Thus, navigation in nondeformity cases is useful for significantly reducing the radiation exposure, but its ability to reduce pedicle screw perforation in nondeformity cases remains to be proven.

Stand-alone Lateral Recess Decompression Without Discectomy in Patients Presenting With Claudicant Radicular Pain and MRI Evidence of Lumbar Disc Herniation: A Prospective Study.

STUDY DESIGN: A prospective study. OBJECTIVE: The aim of this study was to analyze the outcomes of stand-alone lateral recess decompression without discectomy in patients with claudicant radicular pain and magnetic resonance imaging (MRI) showing LRS (lateral recess stenosis) with lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Discectomy is the gold standard treatment for symptomatic lumbar disc herniations refractory to conservative care. Typically, patients with positive SLR (Straight leg raising test) and flexion dominant leg pain are the ideal candidates who can be benefited from discectomy. There is a subset of patients with morphological features of lumbar disc herniation with LRS on MRI and presenting with diametrically opposite symptoms such as claudicant leg pain, extension dominant leg pain, relief on flexion, and a negative SLR. Until now, no focused prospective study in the literature highlights stand-alone lateral recess decompression in this group of patients. METHODS: From January 2007 to June 2013, 55 patients having unilateral claudicant radicular pain were selected to undergo stand-alone lateral recess decompression with tubular retractors. Intraoperatively, disc consistency and presence of sequestrated fragments were analyzed. Visual Analogue Scale (VAS), Oswestry Disability Index (ODI) score, and Macnab criteria were used to measure outcomes. RESULTS: Out of 55 patients, stand-alone lateral recess decompression was successfully executed in 51 patients and remaining four patients had sequestrated discs that required removal. Mean age at presentation was 54.5 years (41-67 years), male:female ratio was 1.12:1, and mean follow-up was 3.8 years (3-5.8 years). Significant improvement (P < 0.0001) was noticed between preoperative and postoperative VAS score (8.39 ±â€Š0.84 vs. 2.5 ±â€Š0.48) and ODI score (46.79 ±â€Š1.85 vs. 18.71 ±â€Š2.41). As per Macnab criteria, 94% patients were satisfied with surgery. CONCLUSION: Stand-alone lateral recess decompression without discectomy is clinically effective for a large majority of patients with claudicant radicular pain and MRI evidence of LRS with associated lumbar disc herniation. The ability to perform it with minimal invasive techniques makes it focused and targeted with minimal morbidity. LEVEL OF EVIDENCE: 4.

Should We Label All Synovial Cysts as Unstable?

STUDY DESIGN: Retrospective study. OBJECTIVE: To analyze the various anatomical parameters that influence segmental stability in patients suffering from lumbar intra spinal cysts (LISCs) and to determine the outcome of microscopic unilateral laminotomy and cystectomy. METHODS: All patients that were surgically managed for a LISC between 2007 and 2013 with more than 3 years of follow-up were reviewed. Those without associated instability were evaluated for segmental mobility, segmental angulation, facet inclination, stage of disc degeneration, and level of involvement on MRI and dynamic radiographs. Outcomes of unilateral laminotomy and cystectomy were evaluated using VAS (Visual Analogue Score), ODI (Oswestry Disability Index), and Macnabs criteria. Dynamic radiographs were performed in all cases pre- and postoperatively and at the last follow-up. RESULTS: Thirty patients were operated for a LISC between 2007 and 2013. The levels involved were L4-5(23), L3-4(4) and L5-S1(3). The mean facet angle was 42.6 (± 6.1) degrees. The stage of disc degeneration was scattered haphazardly across all the cases (Gr 2[17]; Gr 3[1]; Gr 4[8]; Gr 5[4]). VAS and ODI scores improved significantly in all patients. Mean follow-up was 46.5 months (36-96 months). No patient developed postoperative instability at the last follow-up. CONCLUSIONS: The coronal inclination of the facet joints, absence of radiological instability, and poor co-relation with stages of disc degeneration suggests the presence of adequate residual stability. In this study, stand-alone decompression for LISCs without instability had well sustained good/excellent outcomes. Fusion is recommended for LISCs with associated instability.

An unusual case of intradural intramedullary dorsal bronchogenic cyst in spine.

Bronchogenic cysts are congenital malformations derived from anomalous budding of the embryonic foregut. Intraspinal bronchogenic cysts are extremely rare and most of them are extramedullary. There has been only one case of intramedullary spinal bronchogenic cyst reported. We present an 18-year-old male patient with spastic paraparesis and bowel and bladder involvement. MRI revealed a 2 cm diameter intradural and intramedullary lesion at D2-D3 level which was hyperintense on T1 and hypointense on T2 imaging. Histopathological examination after surgical excision of the lesion revealed a bronchogenic cyst. To our knowledge this is the first case reporting an intramedullary bronchogenic cyst at the upper dorsal level and overall second reported case of intramedullary spinal bronchogenic cyst.

Correlation of 1.5 Tesla Magnetic Resonance Imaging with Clinical and Intraoperative Findings for Lumbar Disc Herniation.

STUDY DESIGN: A single-center prospective study. PURPOSE: A magnetic resonance imaging (MRI) scan is undeniably the gold standard for the diagnosis of a lumbar disc prolapse. Unfortunately it shares a strong association with incidental findings. In this study, we aimed to determine the extent to which a 1.5 Tesla MRI correlates with the clinical features and intraoperative findings in cases of lumbar disc prolapse. OVERVIEW OF LITERATURE: Few studies have correlated MRI with clinical findings, and none have extended this correlation to intraoperative findings. METHODS: Over a 2-year period, 50 consecutive patients with lumbar disc herniation requiring discectomy were studied. The MRI findings we observed consisted of the prolapse level, type, position, migration, high-intensity zones (HIZ), lateral recess, and foraminal stenosis. A logistic regression analysis was performed to determine the significance for the various MRI findings. Finally, the MRI observations were confirmed with intraoperative findings and inferences were drawn. RESULTS: MRI scan sensitivity and specificity for determining surgically significant levels was 100% and 94.94%, respectively. Straight leg raising test was positive in 74% of patients, with 85%, 43%, and 75% for paracentral, central, and foraminal levels, respectively. A foraminal compromise was the only MRI parameter to share a significant association with neurological deficits. Patients with a HIZ on the MRI had a significant increase in back pain and 63% exhibited identifiable annular tears intraoperatively. The intraoperative anatomical findings correlated extensively with the MRI findings. CONCLUSIONS: MRI findings strongly correlate with intraoperative features and can serve as a useful tool when planning surgery due to the accurate depiction of the morphometric features. However, the decision for surgery should be made only when detailed clinical findings in conjunction with MRI findings allow for an accurate identification of the culprit fragment and pain generators.

Does Minimally Invasive Spine Surgery Minimize Surgical Site Infections?

STUDY DESIGN: Retrospective review of prospectively collected data. PURPOSE: To evaluate the incidence of surgical site infections (SSIs) in minimally invasive spine surgery (MISS) in a cohort of patients and compare with available historical data on SSI in open spinal surgery cohorts, and to evaluate additional direct costs incurred due to SSI. OVERVIEW OF LITERATURE: SSI can lead to prolonged antibiotic therapy, extended hospitalization, repeated operations, and implant removal. Small incisions and minimal dissection intrinsic to MISS may minimize the risk of postoperative infections. However, there is a dearth of literature on infections after MISS and their additional direct financial implications. METHODS: All patients from January 2007 to January 2015 undergoing posterior spinal surgery with tubular retractor system and microscope in our institution were included. The procedures performed included tubular discectomies, tubular decompressions for spinal stenosis and minimal invasive transforaminal lumbar interbody fusion (TLIF). The incidence of postoperative SSI was calculated and compared to the range of cited SSI rates from published studies. Direct costs were calculated from medical billing for index cases and for patients with SSI. RESULTS: A total of 1,043 patients underwent 763 noninstrumented surgeries (discectomies, decompressions) and 280 instrumented (TLIF) procedures. The mean age was 52.2 years with male:female ratio of 1.08:1. Three infections were encountered with fusion surgeries (mean detection time, 7 days). All three required wound wash and debridement with one patient requiring unilateral implant removal. Additional direct cost due to infection was $2,678 per 100 MISS-TLIF. SSI increased hospital expenditure per patient 1.5-fold after instrumented MISS. CONCLUSIONS: Overall infection rate after MISS was 0.29%, with SSI rate of 0% in non-instrumented MISS and 1.07% with instrumented MISS. MISS can markedly reduce the SSI rate and can be an effective tool to minimize hospital costs.