Minimally invasive tubular removal of spinal schwannoma and neurofibroma - a case series of 49 patients and review of the literature.

To evaluate the efficacy and safety of minimally invasive tubular removal of spinal schwannoma and neurofibroma. In this single-centre study, we retrospectively analysed 49 consecutive patients who underwent minimally invasive removal of a total of 51 benign spinal nerve sheath tumors using a non-expandable (n = 18) or expandable tubular retractor (n = 33) retractor system between June 2007 and December 2019. The extent of resection, surgical complications, neurological outcome, operative time, and estimated blood loss were recorded. Histopathology revealed 41 schwannomas and 10 neurofibromas. After a mean follow-up of 30.8 months, postoperative MRI showed gross total resection in 93.7%, and subtotal resection in 6.3% of the tumors. Three patients were lost to follow up. Of the subtotal resections, one was a schwannoma (2.4% subtotal resections in schwannomas) and two were neurofibromas (20.0% subtotal resections in neurofibromas). Intraspinal and paraspinal tumor localizations were equally accessible by minimally invasive tubular surgery. Conversion to open surgery was not required in any case. The mean operative time was 167 ± 68 min, and estimated blood loss was 138 ± 145 ml. We observed no major surgical complications. Spinal schwannoma and neurofibroma can be removed effectively and safely using a minimally invasive tubular approach, with satisfying extent of tumor resection comparable to the conventional open surgical technique and no increased risk for neurological deterioration.

Minimally invasive resection of a prominent transverse process in neurogenic thoracic outlet syndrome: new application for a primarily spinal approach. Illustrative case.

BACKGROUND: The optimal surgical approach to treat neurogenic thoracic outlet syndrome (nTOS) depends on the individual patient's anatomy as well as the surgeon's experience. The authors present a minimally invasive posterior approach for the resection of a prominent transverse process to reduce local muscular trauma. OBSERVATIONS: A 19-year-old female presented with painful sensations in the right arm and severe fine-motor skill dysfunction in the right hand, each of which had been present for several years. Further examination confirmed affected C8 and T1 areas, and imaging showed an elongated C7 transverse process displacing the lower trunk of the brachial plexus. Decompression of the plexus structures by resection of the C7 transverse process was indicated, owing to persistent neurological effects. Surgery was performed using a minimally invasive posterior approach in which the nuchal soft tissue was bluntly dissected by dilatators and resection of the transverse process was done microscopically through a tubular retractor. The postoperative course showed a sufficient reduction of pain and paresthesia. LESSONS: The authors describe a minimally invasive posterior approach for the treatment of nTOS with the aim of providing indirect relief of strain on brachial plexus structures. The advantages of this technique include a small skin incision and minor soft tissue damage.

Meralgia Paresthetica: Relevance, Diagnosis, and Treatment.

BACKGROUND: Pain and sensory disturbance in the distribution of the lateral femoral cutaneous nerve in the ventrolateral portion of the thigh is called meralgia paresthetica (MP). The incidence of MP has risen along with the increasing prevalence of obesity and diabetes mellitus and was recently estimated at 32 new cases per 100 000 persons per year. In this review, we provide an overview of current standards and developments in the diagnosis and treatment of MP. METHODS: This review is based on publications retrieved by a selective literature search, with special attention to meta-analyses, systematic reviews, randomized and controlled trials (RCTs), and prospective observational studies. RESULTS: The diagnosis is mainly based on typical symptoms combined with a positive response to an infiltration procedure. In atypical cases, electrophysiological testing, neurosonography, and magnetic resonance imaging can be helpful in establishing the diagnosis. The literature search did not reveal any studies of high quality. Four prospective observational studies with small case numbers and partly inconsistent results are available. In a meta-analysis of 149 cases, pain relief was described after infiltration in 85% of cases and after surgery in 80%, with 1-38 months of follow-up. In another meta-analysis of 670 cases, there was pain relief after infiltration in 22% of cases, after surgical decompression in 63%, and after neurectomy in 85%. Hardly any data are available on more recent treatment options, such as radiofrequency therapy, spinal cord stimulation, or peripheral nerve stimulation. CONCLUSION: The state of the evidence is limited in both quantity and quality, corresponding to evidence level 2a for surgical and non-surgical methods. Advances in imaging and neurophysiological testing have made the diagnosis easier to establish. When intervention is needed, good success rates have been achieved with surgery (decompression, neurectomy), and variable success rates with infiltration.

Free-Hand MIS TLIF without 3D Navigation-How to Achieve Low Radiation Exposure for Both Surgeon and Patient.

BACKGROUND: Transforaminal lumbar interbody fusion (TLIF) is one of the most frequently performed spinal fusion techniques, and this minimally invasive (MIS) approach has advantages over the traditional open approach. A drawback is the higher radiation exposure for the surgeon when conventional fluoroscopy (2D-fluoroscopy) is used. While computer-assisted navigation (CAN) reduce the surgeon's radiation exposure, the patient's exposure is higher. When we investigated 2D-fluoroscopically guided and 3D-navigated MIS TLIF in a randomized controlled trial, we detected low radiation doses for both the surgeon and the patient in the 2D-fluoroscopy group. Therefore, we extended the dataset, and herein, we report the radiation-sparing surgical technique of 2D-fluoroscopy-guided MIS TLIF. METHODS: Monosegmental and bisegmental MIS TLIF was performed on 24 patients in adherence to advanced radiation protection principles and a radiation-sparing surgical protocol. Dedicated dosemeters recorded patient and surgeon radiation exposure. For safety assessment, pedicle screw accuracy was graded according to the Gertzbein-Robbins classification. RESULTS: In total, 99 of 102 (97.1%) pedicle screws were correctly positioned (Gertzbein grade A/B). No breach caused neurological symptoms or necessitated revision surgery. The effective radiation dose to the surgeon was 41 ± 12 µSv per segment. Fluoroscopy time was 64 ± 34 s and 75 ± 43 radiographic images per segment were performed. Patient radiation doses at the neck, chest, and umbilical area were 65 ± 40, 123 ± 116, and 823 ± 862 µSv per segment, respectively. CONCLUSIONS: Using a dedicated radiation-sparing free-hand technique, 2D-fluoroscopy-guided MIS TLIF is successfully achievable with low radiation exposure to both the surgeon and the patient. With this technique, the maximum annual radiation exposure to the surgeon will not be exceeded, even with workday use.

Rationale and design of the peripheral nerve tumor registry: an observational cohort study.

AIM: Peripheral nerve tumors (PNT) are rare lesions. To date, no systematic multicenter studies on epidemiology, clinical symptoms, treatment strategies and outcomes, genetic and histopathologic features, as well as imaging characteristics of PNT were published. The main goal of our PNT Registry is the systematic multicenter investigation to improve our understanding of PNT and to assist future interventional studies in establishing hypotheses, determining potential endpoints, and assessing treatment efficacy. METHODS: Aims of the PNT registry were set at the 2015 Meeting of the Section of Peripheral Nerve Surgery of the German Society of Neurosurgery. A study protocol was developed by specialists in PNT care. A minimal data set on clinical status, treatment types and outcomes is reported by each participating center at initial contact with the patient and after 1 year, 2 years, and 5 years. Since the study is coordinated by the Charité Berlin, the PNR Registry was approved by the Charité ethics committee (EA4/058/17) and registered with the German Trials Registry (www.drks.de). On a national level, patient inclusion began in June 2016. The registry was rolled out across Europe at the 2019 meeting of the European Association of Neurosurgery in Dublin. RESULTS: Patient recruitment has been initiated at 10 centers throughout Europe and 14 additional centers are currently applying for local ethics approval. CONCLUSION: To date, the PNT registry has grown into an international study group with regular scientific and clinical exchange awaiting the first results of the retrospective study arm.

The Impact of Implementing a Radiation-Sparing Protocol for Percutaneous Kyphoplasty-A Prospective Dosemetric Study.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: The purpose of this prospective study was to evaluate a protocol for radiation-sparing kyphoplasty by assessing dosemetrically recorded radiation exposures to both patient and surgeon. METHODS: This prospective clinical study examines the radiation exposure to patient and surgeon during single-level kyphoplasty in 32 thoracolumbar osteoporotic vertebral body fractures (12 OF 2, 9 OF 3, 11 OF 4 types) using a radiation aware surgical protocol between May 2017 and November 2019. The radiation exposure was measured at different locations using film, eye lens and ring dosemeters. Dose values are reported under consideration of lower detection limits of each dosemeter type. RESULTS: A high proportion of dosemeter readings was below the lower detection limits, especially for the surgeon (>90%). Radiation exposure to the surgeon was highest at the unprotected thyroid gland (0.053 ± 0.047 mSv), however only slightly above the lower detection limit of dosemeters (0.044 mSv). Radiation exposure to the patient was highest at the chest (0.349 ± 0.414 mSv) and the gonad (0.186 ± 0.262 mSv). Fluoroscopy time, dose area product and number of fluoroscopic images were 46.0 ± 17.9 sec, 124 ± 109 cGy×cm2, and 35 ± 13 per kyphoplasty, respectively. Back pain significantly improved from 6.8 ± 1.6 to 2.5 ± 1.7 on the numeric rating scale on the first postoperative day (P < 0.0001). CONCLUSIONS: The implementation of a strict intraoperative radiation protection protocol allows for safely performed kyphoplasty with ultra-low radiation exposure for the patient and surgeon without exceeding the annual occupational dose limits. TRIAL REGISTRATION: The study was registered in the German Clinical Trials Register (DRKS00011908, registration date 16/05/2017).

The challenge of measuring spinopelvic parameters: inter-rater reliability before and after minimally invasive lumbar spondylodesis.

BACKGROUND: The common manual measurement technique of spinal sagittal alignment on X-rays is susceptible to rater-dependent variability, which has not been adequately considered in previous publications. This study investigates the effect of those variations in the characterization of patients receiving lumbar spondylodesis. METHODS: General alignment parameters on pre- and postoperative X-rays were evaluated by four raters in 43 prospectively sampled patients undergoing monolevel spondylodesis. The Intra-class Correlation Coefficient (ICC) for each rater pair and all raters together was calculated for inter-rater reliability. For the operation-induced change of the sagittal alignment in every patient the Wilcoxon test was applied to compare for each rater separately. RESULTS: The ICCs were "good" (>0.75) to "excellent" (>0.9) for all raters together and for 45 of the 48 single rater pairs (93.75%). All revealed a significant increase of the addressed segmental lordosis and disc height and no significant change for spinopelvic parameters and sagittal vertical axis from pre- to postoperative. The lumbar lordosis showed a significant increase through the operation of +2.5° (p = 0.014) and +3.7° (p = 0.015) in two raters and no difference for the other ones (+2.1°, p = 0.171; -2.2°, p = 0.522). CONCLUSIONS: The pre- to postoperative change of lumbar lordosis revealed different significance levels for different raters, although the ICCs were formally good. Accordingly, the evaluation by only one rater would lead to different conclusions. Due to this susceptibility of alignment measurements to rater-dependent variability, the exact evaluation process should be described in every publication and the consistency of significant results be validated through multiple raters. TRIALS REGISTRATION: The trial was approved by the local ethics committee and listed at the national clinical trials register ( DRKS00004514 , date of registration: 08/11/2012).

Diffusion tensor imaging in unclear intramedullary tumor-suspected lesions allows separating tumors from inflammation.

DESIGN: Prospective diagnostic study. OBJECTIVES: Primary imaging-based diagnosis of spinal cord tumor-suspected lesions is often challenging. The identification of the definite entity is crucial for dedicated treatment and therefore reduction of morbidity. The aim of this trial was to investigate specific quantitative signal patterns to differentiate unclear intramedullary tumor-suspected lesions based on diffusion tensor imaging (DTI). SETTING: Medical Center - University of Freiburg, Germany. METHODS: Forty patients with an unclear tumor-suspected lesion of the spinal cord prospectively underwent DTI. Primary diagnosis was determined by histological or clinical work-up or remained indeterminate with follow-up. DTI metrics (FA/ADC) were evaluated at the central lesion area, lesion margin, edema, and normal spinal cord and compared between different diagnostic groups (ependymomas, other spinal cord tumors, inflammations). RESULTS: Mean DTI metrics for all spinal cord tumors (n = 18) showed significantly reduced FA and increased ADC values compared to inflammatory lesions (n = 8) at the lesion margin (p < 0.001, p = 0.001) and reduced FA at the central lesion area (p < 0.001). There were no significant differences comparing the neoplastic subgroups of ependymomas (n = 10) and other spinal cord tumors (n = 8), but remaining differences for both compared to the inflammation subgroup. We found significant higher ADC (p = 0.040) and a trend to decreased FA (p = 0.081) for ependymomas compared to inflammations at the edema. CONCLUSION: Even if distinct differentiation of ependymomas from other spinal cord neoplasms was not possible based on quantitative DTI metrics, FA and ADC were feasible to separate inflammatory lesions. This may avoid unnecessary surgery in patients with unclear intramedullary tumor-suspected lesions.

Double tubular minimally invasive spine surgery: a novel technique expands the surgical visual field during resection of intradural pathologies.

OBJECTIVE: A major challenge of a minimally invasive spinal approach (MIS) is maintaining freedom of maneuverability through small operative corridors. Unfortunately, during tubular resection of intradural pathologies, the durotomy and its accompanying tenting sutures offer a smaller operating window than the maximum surface of the tube's base. The objective of this study was to evaluate if a novel double tubular technique could expand the surgical visual field during MIS resection of intradural pathologies. METHODS: A total of 25 MIS resections of intradural extramedullary pathologies were included. A posterior tubular interlaminar fenestration was performed in all surgeries. A durotomy covering the whole diameter of the tubular base was the standard in all cases. After placement of two tenting sutures on each side of the durotomy and application of tension, the resulting surface of the achieved dura fenestration was measured after optical analysis of the intraoperative video. In the next step, a second tube, 2 mm thinner than and the same length as the first, was inserted telescopically into the first tube, resulting an angulated fulcrum effect on the tenting sutures. RESULTS: Optical surface analysis of the dura fenestration before and after the second tubular insertion verified a significant widening of the visual field of 43.1% (mean 18.84 mm2, 95% CI 16.8-20.8, p value < 0.001). There were no ruptured tenting sutures through the increased tension. Postoperative MRIs verified complete resection of the pathologies. CONCLUSIONS: Inserting a second tube telescopically during posterior minimally invasive tubular spinal intradural surgery leads to an angulated fulcrum effect on the dura tenting sutures which consequently increases the surface of the dura fenestration and induces a meaningful widening of the visual field.

Autologous platelet-rich fibrin (PRF) augmentation as an add-on therapy in deep surgical site infections (dSSIs) after instrumented spinal surgery: preliminary results of a single institution case series.

BACKGROUND: Deep surgical site infections (dSSIs) after instrumented spinal surgery pose major therapeutic challenges. Standard treatment involves surgical debridement, wound drainage, and long-term antibiotic administration. Autologous platelet-rich fibrin (PRF) constitutes a biomaterial obtained from patients' own blood that contains leukocytes, chemokines and growth factors boosting cicatrization. Due to favorable results reported from other surgical disciplines such as dentistry, orthopedics, maxillofacial and plastic surgery using PRF, the authors hypothesized that PRF augmentation will promote wound healing in dSSIs. OBJECTIVE: To report our preliminary results on the safety and efficacy of autologous-PRF as an add-on therapy on a pilot case series of persistent dSSI after instrumented spinal surgery. METHODS: Among the 293 patients who underwent dorsal decompression and stabilization of the cervical, thoracic, and lumbar spine due to degenerative diseases in our department, 12 patients (4%) presented persisting dSSI after standard wound debridement and antibiotic treatment. PRF augmentation was used during a second surgical revision as an add-on therapy to standard debridement. In all cases, the wound was primarily closed without drains. RESULTS: Wound healing was completed between 14 and 21 days after the second surgical revision in all patients. At a median follow-up of 8 months (range: 6 to 18 months), no recurrence of dSSI nor complications were encountered in any case. CONCLUSIONS: Our preliminary results suggest that PRF augmentation in persistent dSSI after instrumented spinal surgery appears to be a safe and effective strategy to promote wound healing. Prospective controlled studies are required to define the efficiency of PRF more clearly in both treating and preventing dSSI.

Subjective and Objective Change in Cervical Spine Mobility After Single-level Anterior Cervical Decompression and Fusion.

STUDY DESIGN: Prospective, observational study. OBJECTIVE: The aim of this study was to collect objective and especially subjective data on changes in cervical spine mobility after single-level anterior cervical decompression and fusion (ACDF) and to investigate the impact on quality of life and activities of daily living (ADLs). SUMMARY OF BACKGROUND DATA: Although there are several studies dealing with the objective change in mobility after single-level ACDF, there are few data on how spondylodesis of a motion segment affects subjective restriction of cervical spine mobility. METHODS: Patients undergoing first-time, single-level ACDF for a symptomatic spondylotic process were eligible. Data were collected before surgery, at 3-month, and 1-year follow-up. Patients were assessed via clinical scores (pain intensity, Short-Form 8 [SF-8], among others) and asked for impairment in ADLs due to restriction of cervical spine mobility. The subjective restriction was acquired by a five-step patient-reported score. The range of motion was measured by the CROM device. RESULTS: Data of 97 patients could be evaluated. For pain scores and SF-8 there were significant improvements 3 months and 1 year after surgery (P < 0.001). The impairment for most ADLs improved 3 months after surgery and further after 1 year. The subjective restriction showed a significant improvement in general and for all single directions 1 year after surgery. In the objective measurements, a significantly higher total rotation could be found 1 year after surgery compared to preoperatively (101.6° ± 21.2 vs. 93.9° ± 23.4; P = 0.002). There were no significant differences in total flexion-extension and lateral flexion. Increasing age was a significant predictor for objective and subjective restriction. CONCLUSION: The concern of many patients of being severely restricted in their cervical spine mobility after single-level ACDF can be denied. Objectively, the rotation even showed a significant improvement. Regarding the subjective restriction, which is more important for the patients, we found a significant improvement in general and for all directions of movement after surgery.Level of Evidence: 3.

Facet-Sparing Decompression of Lumbar Spinal Stenosis: The Minimally Invasive Bilateral Crossover Approach.

BACKGROUND AND STUDY OBJECTIVE: One risk of established decompression techniques for lumbar spinal stenosis is the resection of facet joints, especially if they are steeply configured, promoting destabilization. Minimally invasive bilateral crossover decompression aims to preserve the facet joints and thus stability of the spine. The purpose of this study is to demonstrate the feasibility and early results of this technique. METHODS: This retrospective case series includes 10 consecutive patients with lumbar stenosis and steep-angle (<35 degrees) facet joints who were treated with minimally invasive bilateral crossover decompression. Eleven segments were decompressed, most commonly L3/L4 (63.6%), followed by L1/L2 and L2/L3 (18.2% each). The effectiveness of surgical decompression was assessed by self-reporting questionnaires. RESULTS: After a follow-up of 10.5 months, the Symptom Severity Scale and Physical Function Scale of the Swiss Spinal Stenosis Questionnaire improved by 0.9 (p < 0.05) and 0.7 points, respectively. The mean Oswestry Disability Index improved from 53.9 to 34.6 (p < 0.05). Local and radiating pain under strain showed statistically significant improvement on the Visual Analog Scale (8.9 vs. 5.0 and 8.4 vs. 4.6, respectively). Maximum walking distance increased from 190 to 1,029 m. Apart from one patient requiring surgical decompression of an adjacent segment, there were no reoperations, neurological deteriorations, or other complications. CONCLUSION: The results of this study indicate that minimally invasive bilateral crossover decompression is a promising technique for the treatment of spinal canal stenosis. With its design to spare facet joints, it can potentially reduce the risk of spinal instability, especially in patients with steep facet joints.

Long-Term Results after Multilevel Fusion of the Cervical Spine and the Cervicothoracic Junction: To Bridge or Not To Bridge?

OBJECTIVE: For patients with multilevel degenerative cervical myelopathy, laminectomy and fusion are widely accepted techniques for ameliorating the disorder. However, the idea of whether one should bridge the cervicothoracic junction to prevent instrument failure or adjacent segment disease has been a subject of controversial discussion. In the present study, we compared the incidence of these complications and the revision rates in multilevel fusions extending to C7 or T1-T3. METHODS: In the present single-center, retrospective cohort study, patients with multilevel degenerative cervical myelopathy treated with laminectomy and fusion to C7 or T1-T3 from 2004 to 2016 were included for evaluation. The primary outcome measure was radiologically proven complications at the most caudal level or the adjacent spinal fusion level. RESULTS: Laminectomy and multilevel fusion were performed in 84 patients. After applying the exclusion criteria, 20 patients with fusion to C7 (treated from 2004 to 2012; follow-up, 124.6 ± 10.6 months) and 38 patients with fusion to T1-T3 (treated from 2008 to 2016; follow-up, 58.2 ± 15.7 months) were evaluated. The incidence of complications at the most caudal or adjacent level of fusion was twice as high (P = 0.087; NS) in the C7 group (11 of 20; 55.0%) compared with the T1-T3 group (11 of 38; 28.9%). In the C7 group, 9 of the 20 patients (45.0%) had required revision surgery compared with 2 of 38 patients (5.3%) in the T1-T3 group (P = 0.001). CONCLUSIONS: We found that fewer revisions were necessary if the fusion had extended to the thoracic spine. Thus, we recommend bridging the cervicothoracic junction when fusion starts at C0-C3.

Radiation Exposure to Scrub Nurse, Assistant Surgeon, and Anesthetist in Minimally Invasive Spinal Fusion Surgery Comparing 2D Conventional Fluoroscopy With 3D Fluoroscopy-based Navigation: A Randomized Controlled Trial.

STUDY DESIGN: A randomized controlled trial. OBJECTIVE: To compare the radiation exposure with the scrub nurse, assistant surgeon, and anesthetist during minimally invasive transforaminal lumbar interbody fusion using conventional 2-dimensional (2D) fluoroscopy or 3D fluoroscopy-based navigation. SUMMARY OF BACKGROUND DATA: Minimally invasive spinal fusion techniques are related to higher radiation exposures compared with open techniques. Especially the routinely exposed surgical staff faces the risks of increased radiation exposure. METHODS: In total, 41 patients with planned monosegmental minimally invasive transforaminal lumbar interbody fusion were randomized into the intraoperative imaging techniques 2D fluoroscopy or 3D navigation. Eye lens and film dosemeters were attached to defined locations of the scrub nurse, assistant surgeon, and anesthetist. Mann-Whitney U and Wilcoxon-matched pairs signed-rank test were used to compare dosemeter readings. This study was registered with the German Clinical Trials Register (DRKS00004514). RESULTS: The radiation exposure per surgery was low for the scrub nurse, assistant surgeon, and anesthetist in both the 2D fluoroscopy and 3D navigation groups. The maximum average value of 0.057±0.031 mSv was measured on the unprotected chest of the assistant surgeon and was thus slightly above the lower detection limit of the dosemeters (0.044 mSv). The annual occupational dose limit would be exceeded at the earliest after 571 operations for the unprotected eye lens of the assistant surgeon. CONCLUSIONS: Minimally invasive lumbar fusion surgery is possible with comparatively low radiation exposure to the assisting operating room personnel without exceeding the annual maximum occupational radiation exposure. However, there is no definite dose value below which ionizing radiation poses no risk. Consequently, radiation sparing work routines should be strictly followed.

Radiation Exposure in Minimally Invasive Lumbar Fusion Surgery: A Randomized Controlled Trial Comparing Conventional Fluoroscopy and 3D Fluoroscopy-based Navigation.

STUDY DESIGN: Randomized controlled trial. OBJECTIVE: The aim of this study was to compare the dosemetrically determined radiation exposure of surgeon and patient during minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) using conventional 2D fluoroscopy (FLUORO) or 3D fluoroscopy-based navigation (NAV). SUMMARY OF BACKGROUND DATA: MIS TLIF was shown to exhibit higher radiation exposures compared to open techniques. In particular, the routinely exposed surgeon encounters the risks of increased radiation doses. With the additional use of intraoperative 3D navigation, major steps of the operation can be performed without exposing the operating room staff to ionizing radiation. METHODS: Forty-four patients undergoing monosegmental MIS TLIF were randomized into the two intraoperative imaging technique groups (FLUORO or NAV). The primary endpoint was the radiation exposure of the surgeon; the secondary endpoints were the radiation exposure of the patient and C-arm readings. RESULTS: After exclusion of three patients, 41 patients were analyzed. In general, the average radiation exposure of the surgeon was lower in the NAV group without being statistically significant. The radiation exposure of the patient was significantly higher in the NAV group at all dosemeter sites. The average fluoroscopy time was 63 ±â€Š36 versus 109 ±â€Š31 sec (FLUORO versus NAV group, P < 0.001). CONCLUSION: The additional use of intraoperative 3D fluoroscopy-based navigation compared to conventional 2D fluoroscopy alone showed a nonsignificant reduction of the radiation exposure of the surgeon in monosegmental MIS TLIF, while increasing the radiation exposure of the patient. LEVEL OF EVIDENCE: 1.

Cranial facet joint injuries in percutaneous lumbar pedicle screw placement: a matched-pair analysis comparing intraoperative 3D navigation and conventional fluoroscopy.

PURPOSE: The violation of the cranial adjacent facet is a frequent complication in lumbar instrumentations and can induce local pain and adjacent segment disease. Minimally invasive screw implantation is often stated as risk factor in comparison with open approaches. Percutaneous pedicle screw placement (PPSP) can be performed using single X-ray images (fluoroscopy) or intraoperative 3D navigation. The study compares top-level screws in percutaneous lumbar instrumentations regarding facet violations and screw pedicle position using navigation or fluoroscopy. METHODS: Patients after lumbar PPSP were retrospectively separated according to the intraoperative technique: navigation (NAV) or fluoroscopy (FLUORO). Two blinded investigators graded the top-level screws regarding facet violations and pedicle breach in postoperative CT scans. Subsequent matched cohort analysis was performed for comparable groups. RESULTS: Evaluating 768 screws, we assessed 70 (9.1%) facet violations. Overall, 186 (24.2%) screws were implanted using navigation. There was no significant difference in the rate of facet violations between both imaging groups (NAV 19/186, 10.2%, FLUORO 51/582, 8.8%, p = 0.55). Totally, 728 (94.8%) of all screws showed a correct pedicle position. Most of the 40 unfavorable pedicle positions were placed by fluoroscopy (NAV 4/186, 2.2%, FLUORO 36/582, 6.6%, p = 0.03). The matched cohorts verified these results (facet violations: NAV 19/186, 10.2%, FLUORO 18/186, 9.7%, p = 0.55; pedicle penetrations: NAV 4/186, 2.2%, FLUORO 12/186, 6.9%, p = 0.04). CONCLUSIONS: Both intraoperative imaging techniques allow lumbar PPSP with low rates of cranial facet violations if the surgeon intends to preserve facet integrity. Navigation was superior concerning accurate pedicle screw position, but could not significantly prevent facet violations.

Radiation exposure of a mobile 3D C-arm with large flat-panel detector for intraoperative imaging and navigation - an experimental study using an anthropomorphic Alderson phantom.

BACKGROUND: Intraoperative 3-dimensional (3D) navigation is increasingly being used for pedicle screw placement. For this purpose, dedicated mobile 3D C-arms are capable of providing intraoperative fluoroscopy-based 3D image data sets. Modern 3D C-arms have a large field of view, which suggests a higher radiation exposure. In this experimental study we therefore investigate the radiation exposure of a new mobile 3D C-arm with large flat-panel detector to a previously reported device with regular flat-panel detector on an Alderson phantom. METHODS: We measured the radiation exposure of the Vision RFD 3D (large 30 × 30 cm detector) while creating 3D image sets as well as standard fluoroscopic images of the cervical and lumbar spine using an Alderson phantom. The dosemeter readings were then compared with the radiation exposure of the previous model Vision FD Vario 3D (smaller 20 × 20 cm detector), which had been examined identically in advance and published elsewhere. RESULTS: The larger 3D C-arm induced lower radiation exposures at all dosemeter sites in cervical 3D scans as well as at the sites of eye lenses and thyroid gland in lumbar 3D scans. At ​​male and especially female gonads in lumbar 3D scans, however, the larger 3D C-arm showed higher radiation exposures compared with the smaller 3D C-arm. In lumbar fluoroscopic images, the dosemeters near/in the radiation field measured a higher radiation exposure using the larger 3D C-arm. CONCLUSIONS: The larger 3D C-arm offers the possibility to reduce radiation exposures for specific applications despite its larger flat-panel detector with a larger field of view. However, due to the considerably higher radiation exposure of the larger 3D C-arm during lumbar 3D scans, the smaller 3D C-arm is to be recommended for short-distance instrumentations (mono- and bilevel) from a radiation protection point of view. The larger 3D C-arm with its enlarged 3D image set might be used for long instrumentations of the lumbar spine. From a radiation protection perspective, the use of the respective 3D C-arm should be based on the presented data and the respective application.

Noninvasive patient tracker mask for spinal 3D navigation: does the required large-volume 3D scan involve a considerably increased radiation exposure?

OBJECTIVE: Intraoperative 3D imaging and navigation is increasingly used for minimally invasive spine surgery. A novel, noninvasive patient tracker that is adhered as a mask on the skin for 3D navigation necessitates a larger intraoperative 3D image set for appropriate referencing. This enlarged 3D image data set can be acquired by a state-of-the-art 3D C-arm device that is equipped with a large flat-panel detector. However, the presumably associated higher radiation exposure to the patient has essentially not yet been investigated and is therefore the objective of this study. METHODS: Patients were retrospectively included if a thoracolumbar 3D scan was performed intraoperatively between 2016 and 2019 using a 3D C-arm with a large 30 × 30-cm flat-panel detector (3D scan volume 4096 cm3) or a 3D C-arm with a smaller 20 × 20-cm flat-panel detector (3D scan volume 2097 cm3), and the dose area product was available for the 3D scan. Additionally, the fluoroscopy time and the number of fluoroscopic images per 3D scan, as well as the BMI of the patients, were recorded. RESULTS: The authors compared 62 intraoperative thoracolumbar 3D scans using the 3D C-arm with a large flat-panel detector and 12 3D scans using the 3D C-arm with a small flat-panel detector. Overall, the 3D C-arm with a large flat-panel detector required more fluoroscopic images per scan (mean 389.0 ± 8.4 vs 117.0 ± 4.6, p < 0.0001), leading to a significantly higher dose area product (mean 1028.6 ± 767.9 vs 457.1 ± 118.9 cGy × cm2, p = 0.0044). CONCLUSIONS: The novel, noninvasive patient tracker mask facilitates intraoperative 3D navigation while eliminating the need for an additional skin incision with detachment of the autochthonous muscles. However, the use of this patient tracker mask requires a larger intraoperative 3D image data set for accurate registration, resulting in a 2.25 times higher radiation exposure to the patient. The use of the patient tracker mask should thus be based on an individual decision, especially taking into considering the radiation exposure and extent of instrumentation.

How Safe Is Minimally Invasive Transforaminal Lumbar Interbody Fusion for Octogenarians?: A Perioperative Complication Analysis.

BACKGROUND: Technical advances in minimally invasive spine surgery have reduced blood loss, access trauma, and postoperative length of stay. However, operating on the susceptible group of octogenarians still poses a dilemma because of a plethora of age-related comorbidities. The aim of this study was to investigate the safety of minimally invasive surgery (MIS) transforaminal lumbar interbody fusion (TLIF) in octogenarians. METHODS: We conducted a retrospective single-center study of all patients over 80 years of age who, between March 2009 and February 2014, had undergone MIS TLIF. The primary outcome was recorded major and minor complications within 30 days of surgery. RESULTS: Twenty-one patients with an average age of 84.1 ± 2.7 years underwent MIS TLIF in 31 levels for degenerative lumbar disk disease with intolerable pain after failure of conservative treatment. Of the patients, 33.3% showed no perioperative complications. In the remaining 66.7%, 6 major complications and 24 minor complications occurred within 30 days of surgery. Two of these patients died within 30 days of surgery because of sepsis and pulmonary embolism (mortality rate 9.5%). CONCLUSIONS: Our study spotlighted the susceptible group of octogenarians and evaluated the safety of MIS TLIF. The perioperative morbidity for octogenarians undergoing MIS TLIF is substantial and even higher than for patients over 65 years of age. Two thirds of patients in this subgroup suffer at least 1 complication. The 30-day mortality rate was 9.5%. Therefore, it is advisable for these patients to exploit all available conservative options prior to surgery.