Study DesignRetrospective review of prospectively collected data.PurposeTo 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 LiteratureSSI 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.MethodsAll 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.ResultsA 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.ConclusionsOverall 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.

Study DesignProspective cohort study.PurposeTo 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 LiteratureThe 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.MethodsEighty-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.ResultsTwenty-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.ConclusionsNavigation 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.

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.

Study DesignA single-center prospective study.PurposeA 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 LiteratureFew studies have correlated MRI with clinical findings, and none have extended this correlation to intraoperative findings.MethodsOver 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.ResultsMRI 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.ConclusionsMRI 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.

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.