Motion is reduced in the unstable spine with the use of mechanical devices for bed transfers.

CONTEXT: Excessive spinal motion generated during multiple bed transfers of patients with unstable spine injuries may contribute to neurological deterioration. OBJECTIVE: To evaluate spinal motion in a cadaveric model of global spinal instability during hospital bed transfers using several commonly used techniques. DESIGN/PARTICIPANTS: A motion analysis and evaluation of hospital bed transfer techniques in a cadaveric model of C5-C6 and T12-L2 global spinal instability. Setting/outcome measures: Global instability at C5-C6 and T12-L2 was created. The motion in three planes was measured in both the cervical and lumbar spine during each bed transfer via electromagnetic motion detection devices. Comparisons between transfers performed using an air-assisted lateral transfer device, manual transfer, a rolling board, and a sliding board were made based on the maximum range of motion observed. RESULTS: Significantly less lateral bending at C5-C6 was observed in air-assisted device transfers when compared with the two other boards. Air-assisted device transfers produced significantly less axial rotation at T12-L2 than the rolling board, and manual transfers produced significantly less thoracolumbar rotation than both the rolling and sliding boards. No other significant differences were observed in cervical or lumbar motion. Motion versus time plots indicated that the log roll maneuvers performed during rolling board and sliding board transfers contributed most of the observed motion. CONCLUSIONS: Each transfer technique produced substantial motion. Transfer techniques that do not include the logroll maneuver can significantly decrease some components of cervical and lumbar motion. Thus, some spinal motion can be reduced through selection of transfer technique.

Does intraoperative neurophysiological monitoring have predictive value for functional recovery following spinal cord injury? A case report.

To present a case report of a patient with an ASIA B spinal cord injury with partially intact baseline IONM who made a complete functional recovery postoperatively. A thirty-three year old male presented after a motor vehicle accident. Imaging studies revealed a C4-C5 bilateral facet dislocation. On presentation the patient had 4/5 strength in bilateral biceps and wrist extensors, 3/5 strength in bilateral triceps, and 0/5 strength in the finger flexors, intrinsics and all lower extremity muscles. Motor level was C7. Sensation was grossly intact to light touch throughout all extremities, intact to pinprick from C2 to T7, and absent to pinprick caudal to T7. Rectal tone and contraction were absent. After attempts at closed reduction failed the patient underwent an open reduction and posterior C4-C5 fusion. Intraoperative neurophysiologic monitoring (IONM) revealed the presence of baseline responses to the posterior tibial nerve using somatosensory evoked potentials and to the right abductor hallucis using transcranial motor evoked potentials. At the 6 weeks postoperative visit the patient had full 5/5 motor strength to all muscles except the left deltoid that was 4/5 due to a rotator cuff injury. This case illustrates a potential prognostic value of IONM. Despite lack of clinical motor function at the time of surgery, IONM was able to illicit a motor response in the right lower extremity. Further prospective studies are needed for further investigation.

Lumbar Discectomy With Bone-Anchored Annular Closure Device in Patients With Large Annular Defects: One-Year Results.

BACKGROUND: Reherniation rates following lumbar discectomy are low for most patients; however, patients with a large defect in the annulus fibrosis have a significantly higher risk of recurrence. Previous results from a randomized controlled trial (RCT) demonstrated that the implantation of a bone-anchored annular closure device (ACD) during discectomy surgery lowered the risk of symptomatic reherniation and reoperation over one year with fewer serious adverse events (SAEs) compared to discectomy alone. OBJECTIVE: The objective of this prospective, post-market, historically controlled study was to evaluate the use of an ACD during discectomy, and to confirm the results of the RCT that was used to establish regulatory approval in the United States. METHODS: In this post-market study, all patients (N = 55) received discectomy surgery with a bone-anchored ACD. The comparison population was patients enrolled in the RCT study who had discectomy with an ACD (N = 262) or discectomy alone (N = 272). All other eligibility criteria, surgical technique, device characteristics, and follow-up methodology were comparable between studies. Endpoints included rate of symptomatic reherniation or reoperation, SAEs, and patient-reported measures of disability, pain, and quality of life. RESULTS: Fifty-five patients received ACD implants at 12 sites between May 2020 and February 2021. In the previous RCT, 272 control patients had discectomy surgery alone (RCT-Control), and 262 patients had discectomy surgery with an ACD implant (RCT-ACD). Baseline characteristics across groups were typical of the overall population undergoing lumbar discectomy. The proportion of patients who experienced reherniation and/or reoperation was significantly lower in the ACD group compared to RCT-ACD and RCT-Control groups (p < 0.05). In the ACD study, the one-year rate of symptomatic reherniation was 3.7%, compared to 8.5% in the RCT-ACD group and 17.0% in the RCT-Control group. In the ACD group, the risk of reoperation was 5.5%, compared to 6.5% in the RCT-ACD group and 12.5% in the RCT-Control group. There were no device-related SAEs or device integrity failures in the ACD, and there were clinically meaningful improvements in patient-reported measures of disability, pain, and quality of life. CONCLUSION: In this post-market study of bone-anchored ACD in patients with large annular defects, rates of symptomatic reherniation, reoperation, and SAEs were all low. Compared to the RCT, the post-market ACD study demonstrated lower rates of reherniation and/or reoperation and measures of back pain one-year post-surgery.

Removing a patient from the spine board: is the lift and slide safer than the log roll?

BACKGROUND: After spine board immobilization of the trauma victim and transport to the hospital, the patient is removed from the spine board as soon as practical. Current Advanced Trauma Life Support's recommendations are to log roll the patient 90 degrees, remove the spine board, inspect and palpate the back, and then log roll back to supine position. There are several publications showing unacceptable motion in an unstable spine when log rolling. METHODS: Cervical spine motion was evaluated during spine board removal. A C5 to C6 instability was surgically created in cadavers. A three-dimensional electromagnetic tracking system was used to assess motion between C5 and C6. The log roll was compared with a lift-and-slide technique. Throughout the log roll procedure, manual inline cervical stabilization was provided by a trained individual in a series of trials. In other trials, the lift-and-slide technique was used. In the final stage, the amount of motion generated was assessed when the spine board removal techniques were completed by experienced and novice persons in maintaining inline stabilization of the head and neck. RESULTS: Motion between C5 and C6 was reduced during the lift-and-slide technique in five of six parameters. The reduction was statistically significant in four parameters. When performing the log roll, motion was not reduced with increased head holder experience. CONCLUSIONS: Spine boards can be removed using a lift-and-slide maneuver with less motion and potentially less risk to the patient's long-term neurologic function than expected using the log roll.

Cervical collars are insufficient for immobilizing an unstable cervical spine injury.

BACKGROUND: Cervical orthoses are commonly used for extrication, transportation, and definitive immobilization for cervical trauma patients. Various designs have been tested frequently in young, healthy individuals. To date, no one has reported the effectiveness of collar immobilization in the presence of an unstable mid-cervical spine. STUDY OBJECTIVES: To determine the extent to which cervical orthoses immobilize the cervical spine in a cadaveric model with and without a spinal instability. METHODS: This study used a repeated-measures design to quantify motion on multiple axes. Five lightly embalmed cadavers with no history of cervical pathology were used. An electromagnetic motion-tracking system captured segmental motion at C5-C6 while the spine was maneuvered through the range of motion in each plane. Testing was carried out in intact conditions after a global instability was created at C5-C6. Three collar conditions were tested: a one-piece extraction collar (Ambu Inc., Linthicum, MD), a two-piece collar (Aspen Sierra, Aspen Medical Products, Irvine, CA), and no collar. Gardner-Wells tongs were affixed to the skull and used to apply motion in flexion-extension, lateral bending, and rotation. Statistical analysis was carried out to evaluate the conditions: collar use by instability (3 × 2). RESULTS: Neither the one- nor the two-piece collar was effective at significantly reducing segmental motion in the stable or unstable condition. There was dramatically more motion in the unstable state, as would be expected. CONCLUSION: Although using a cervical collar is better than no immobilization, collars do not effectively reduce motion in an unstable cervical spine cadaver model. Further study is needed to develop other immobilization techniques that will adequately immobilize an injured, unstable cervical spine.

Lumbar Discectomy With Barricaid Device Implantation in Patients at High Risk of Reherniation: Initial Results From a Postmarket Study.

Background Patients with large defects in the annulus fibrosus following lumbar discectomy have high rates of symptomatic reherniation and reoperation. An FDA randomized controlled trial (RCT) with a bone-anchored device (Barricaid, Intrinsic Therapeutics, Woburn, MA) that occludes the annular defect reported significantly lower risk of symptomatic reherniation and reoperation compared to patients receiving discectomy only. However, results of the Barricaid device in real-world use remain limited.  Methods This was a post-market study to determine the real-world outcomes of the Barricaid device when used in addition to primary lumbar discectomy in patients with large annular defects. Main outcomes included leg pain severity, Oswestry Disability Index (ODI), adverse events, symptomatic reherniation, and reoperation. Imaging studies were read by an independent imaging core laboratory. This paper reports the initial three-month primary endpoint results from the trial; one-year patient follow-up is ongoing. Results Among 55 patients (mean age 41±13 years, 60% male), the mean percent reduction in leg pain severity was 92%, and the mean percent reduction in ODI score was 79%. The three-month rate of symptomatic reherniation was 3.6% and the rate of reoperation was 1.8%. The serious adverse event rate was 5.5%; no device migrations or fractures were observed.  Conclusion Among patients with large annular defects following lumbar discectomy treated with the Barricaid device in real-world conditions, early results demonstrated clinically meaningful improvements in patient symptoms and low rates of symptomatic reherniation, reoperation, and complications, which were comparable to those observed with the device in an FDA-regulated trial.

Does the ACS NSQIP Surgical Risk Calculator Accurately Predict Complications Rates After Anterior Lumbar Interbody Fusion Procedures?

STUDY DESIGN: Clinical case series. OBJECTIVE: The aim of this study was to determine the effectiveness of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) surgical risk calculator in the prediction of complications after anterior lumbar interbody fusion (ALIF). SUMMARY OF BACKGROUND DATA: Identifying at-risk patients may aid in the prevention of complications after spine procedures. The ACS NSQIP surgical risk calculator was developed to predict 30-day postoperative complications for a variety of operative procedures. METHODS: Medical records of patients undergoing ALIF at our institution from 2009 to 2019 were retrospectively reviewed. Demographic and comorbidity variables were entered into the ACS NSQIP surgical risk calculator to generate percentage predictions for complication incidence within 30 days postoperatively. The observed incidences of these complications were also abstracted from the medical record. The predictive ability of the ACS NSQIP surgical risk calculator was assessed in comparison to the observed incidence of complications using area under the curve (AUC) analyses. RESULTS: Two hundred fifty-three (253) patients were analyzed. The ACS NSQIP surgical risk calculator was a fair predictor of discharge to non-home facility (AUC 0.71) and surgical site infection (AUC 0.70). The ACS NSQIP surgical risk calculator was a good predictor of acute kidney injury/progressive renal insufficiency (AUC 0.81). The ACS NSQIP surgical risk calculator was not an adequate predictive tool for any other category, including: pneumonia, urinary tract infections, venous thromboembolism, readmission, reoperations, and aggregate complications (AUC < 0.70). CONCLUSION: The ACS NSQIP surgical risk calculator is an adequate predictive tool for a subset of complications after ALIF including acute kidney injury/progressive renal insufficiency, surgical site infections, and discharge to non-home facilities. However, it is a poor predictor for all other complication groups. The reliability of the ACS NSQIP surgical risk calculator is limited, and further identification of models for risk stratification is necessary for patients undergoing ALIF.Level of Evidence: 3.

Multicenter study of lumbar discectomy with Barricaid annular closure device for prevention of lumbar disc reherniation in US patients: A historically controlled post-market study protocol.

BACKGROUND: Patients with large defects in the annulus fibrosus following lumbar discectomy have high rates of symptomatic reherniation. The Barricaid annular closure device provides durable occlusion of the annular defect and has been shown to significantly lower the risk of symptomatic reherniation in a large European randomized trial. However, the performance of the Barricaid device in a United States (US) population has not been previously reported. DESIGN AND METHODS: This is a historically controlled post-market multicenter study to determine the safety and efficacy of the Barricaid device when used in addition to primary lumbar discectomy in a US population. A total of 75 patients with large annular defects will receive the Barricaid device following lumbar discectomy at up to 25 sites in the US and will return for clinical and imaging follow-up at 4 weeks, 3 months, and 1 year. Trial oversight will be provided by a data safety monitoring board and imaging studies will be read by an independent imaging core laboratory. Patients treated with the Barricaid device in a previous European randomized trial with comparable eligibility criteria, surgical procedures, and outcome measures will serve as historical controls. Main outcomes will include back pain severity, leg pain severity, Oswestry Disability Index, health utility on the EuroQol-5 Dimension questionnaire, complications, symptomatic reherniation, and reoperation. Propensity score adjustment using inverse probability of treatment weighting will be used to adjust for differences in baseline patient characteristics between the US trial participants and European historical controls. ETHICS AND DISSEMINATION: This study was approved by a central institutional review board. The study results of this trial will be widely disseminated at conference proceedings and published in peer-reviewed journals. The outcomes of this study will have important clinical and economic implications for all stakeholders involved in treating patients with lumbar discectomy in the US. STUDY REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov): NCT03986580. LEVEL OF EVIDENCE: 3.

Screw orientation and plate type (variable- vs. fixed-angle) effect strength of fixation for in vitro biomechanical testing of the Synthes CSLP.

BACKGROUND CONTEXT: Two common justifications for orienting cervical screws in an angled direction are to increase pullout strength and to allow use of longer screws. This concept is widely taught and has guided implant design. Fixed- versus variable-angle systems may offer strength advantages. Despite these teachings, there is a paucity of supporting biomechanical evidence. The purpose of our study is to test the influence of screw orientation and plate design on the maximum screw pullout force. PURPOSE: This study evaluates the effect of screw orientation and plate type (fixed- vs. variable-angle) on screw pullout strength. STUDY DESIGN: Anterior cervical plates of both a fixed- and variable-angle CSLP, were tested for peak pullout strength in a direct plate pullout model using polyurethane foam bone, which models osteoporotic bone. METHODS: Self-tapping, locking screws (4.0x14mm and 4.0x16mm) were used. Screws were oriented in the fixed-angle plate in the standard fashion. In the variable plate, screws were instrumented in three different orientations. Biomechanical testing was performed on an Instron DynaMight 8841 servohydraulic testing machine, measuring maximum pullout force under a displacement-controlled pullout rate of 1mm/min. Five samples were tested per group. RESULTS: When all screws were placed 90 degrees to the plate, there was a significantly increased peak pullout strength (412.8+/-22.2N) compared with when all screws were placed 12 degrees "up and in" (376.2+/-24.3N, p less than or equal to .03). When the 90 degrees construct was reproduced using 14-mm screws and compared with 16-mm screws oriented 12 degrees "all up and in," there was still significantly higher pullout strength with the all 90 degrees construct (434.2+/-28.7N vs. 376.2+/-24.3N, p less than or equal to .009). The fixed-angle plate had a significantly decreased peak pullout strength (288.2+/-15.7N) compared with the variable-angle plate (416.6+/-12.6N) (p less than .00001) when the screws were placed in the same orientation. Overall, the variable-angle plate, regardless of the orientation of screws, had a significantly greater pullout strength than the fixed-angle plate (p less than .001). CONCLUSIONS: In this system, a variable-angle plate has greater pullout strength than a fixed-angle plate, regardless of the orientation of screws. With the variable-angle plate, a construct of all screws 12 degrees "up and in" is the weakest configuration. We found that with the 90 degrees construct, both 16- and 14-mm screws performed significantly better than 16-mm convergent screws. These findings are remarkable because they contradict the current doctrine. This may be a function of plate-dependent factors and should not be applied universally to all plate systems. Further study of screw orientation in additional plating systems is warranted.

Posterior lumbar interbody fusion.

Posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) create intervertebral fusion by means of a posterior approach. Both techniques are useful in managing degenerative disk disease, severe instability, spondylolisthesis, deformity, and pseudarthrosis. Successful results have been reported with allograft, various cages (for interbody support), autograft, and recombinant human bone morphogenetic protein-2. Interbody fusion techniques may facilitate reduction and enhance fusion. The rationale for PLIF and TLIF is biomechanically sound. However, clinical outcomes of different anterior and posterior spinal fusion techniques tend to be similar. PLIF has a high complication rate (dural tear, 5.4% to 10%; neurologic injury, 9% to 16%). These findings, coupled with the versatility of TLIF throughout the entire lumbar spine, may make TLIF the ideal choice for an all-posterior interbody fusion.

Incidence and risk of delayed surgical site infection following instrumented lumbar spine fusion.

We reviewed a retrospective case series of patients with delayed infections after spinal fusion, and surveyed medical experts in Canada and the USA regarding their use of prophylactic antibiotics for patients undergoing invasive procedures following spine surgery. Infections after spinal fusion are a relatively common complication, which typically occur early in the postoperative period. Infections which occur more than 3months from the index procedure are rare and are often caused by atypical pathogens. The proportion of infections that required debridement and occurred 6 months after the index procedure was 4.3% (7/162). Over 85% of these infections were polymicrobial, with one third of those containing methicillin-resistant Staphylococcus aureus. The most common operative indications were either trauma or tumour, and most patients with a delayed infection had a distant chronic infection. The majority of spine experts do not routinely recommend prophylactic antibiotics for invasive procedures after spine fusion. In the multivariate analysis, experts were more likely to recommend antibiotics for patients undergoing a non-dental procedure, those who were diabetic, and those who were greater than 1year out from their procedure. In summary, the delayed presentation of infection after instrumented spinal fusion is a rare but serious complication. However, due to its infrequency, routine prophylaxis to prevent haematogenous seeding is likely unnecessary.

A comparison of the Wiltse versus midline approaches in degenerative conditions of the lumbar spine.

OBJECTIVE The objective of this study was to determine if there is a significant difference in surgical site infection (SSI) when comparing the Wiltse and midline approaches for posterior instrumented interbody fusions of the lumbar spine and, secondarily, to evaluate if the reoperation rates and specific causes for reoperation were similar for both approaches. METHODS A total of 358 patients who underwent 1- or 2-level posterior instrumented interbody fusions for degenerative lumbar spinal pathology through either a midline or Wiltse approach were prospectively followed between March 2005 and January 2011 at a single tertiary care facility. A retrospective analysis was performed primarily to evaluate the incidence of SSI and the incidence and causes for reoperation. Secondary outcome measures included intraoperative complications, blood loss, and length of stay. A matched analysis was performed using the Fisher's exact test and a logistic regression model. The matched analysis controlled for age, sex, comorbidities, number of index levels addressed surgically, number of levels fused, and the use of bone grafting. RESULTS All patients returned for follow-up at 1 year, and adverse events were followed for 2 years. The rate of SSI was greater in the midline group (8 of 103 patients; 7.8%) versus the Wiltse group (1 of 103 patients; 1.0%) (p = 0.018). Fewer additional surgical procedures were performed in the Wiltse group (p = 0.025; OR 0.47; 95% CI 0.23-0.95). Proximal adjacent segment failure requiring reoperation occurred more frequently in the midline group (15 of 103 patients; 14.6%) versus the Wiltse group (6 of 103 patients; 5.8%) (p = 0.048). Blood loss was significantly lower in the Wiltse group (436 ml) versus the midline group (703 ml); however, there was no significant difference between the 2 groups in intraoperative complications or length of stay. CONCLUSIONS The patients who underwent the Wiltse approach had a decreased risk of wound breakdown and infection, less blood loss, and fewer reoperations than the midline patients. The risk of adjacent segment failure in short posterior constructs is lower with a Wiltse approach.

Molecular signaling in intervertebral disk development.

The purpose of this investigation is to identify and study the expression pattern of pertinent molecular factors involved in the differentiation of the intervertebral disk (IVD). It is likely that hedgehog genes and the BMP inhibitors are key factors involved in spinal joint formation. Radioactive in situ hybridization with mRNA probes for pax-1, SHH, IHH and Noggin gene was performed on mouse embryo and adult tissue. Immunohistochemistry was performed to localize hedgehog receptor, "patched" (ptc). From 14.5 dpc until birth pax-1 mRNA was expressed in the developing anulus fibrosus (AF). During the same developmental period Noggin mRNA is highly expressed throughout the spine, in the developing AF, while ptc protein and SHH mRNA were expressed in the developing nucleus pulposus (NP). IHH mRNA was expressed by condensing chondrocytes of the vertebral bodies and later becomes confined to the vertebral endplate. We show for the first time that pax-1 is expressed in the adult intervertebral disk. Ptc expression in the NP is an indicator of hedgehog protein signaling in the developing IVD. The expression pattern of the BMP inhibitor Noggin appears to be important for the normal formation of the IVD and may prove to play a role in its segmental pattern formation.

Controlled Laboratory Comparison Study of Motion With Football Equipment in a Destabilized Cervical Spine: Three Spine-Board Transfer Techniques.

BACKGROUND: Numerous studies have shown that there are better alternatives to log rolling patients with unstable spinal injuries, although this method is still commonly used for placing patients onto a spine board. No previous studies have examined transfer maneuvers involving an injured football player with equipment in place onto a spine board. PURPOSE: To test 3 different transfer maneuvers of an injured football player onto a spine board to determine which method most effectively minimizes spinal motion in an injured cervical spine model. STUDY DESIGN: Controlled laboratory study. METHODS: Five whole, lightly embalmed cadavers were fitted with shoulder pads and helmets and tested both before and after global instability was surgically created at C5-C6. An electromagnetic motion analysis device was used to assess the amount of angular and linear motion with sensors placed above and below the injured segment during transfer. Spine-boarding techniques evaluated were the log roll, the lift and slide, and the 8-person lift. RESULTS: The 8-person lift technique resulted in the least amount of angular and linear motion for all planes tested as compared with the lift-and-slide and log-roll techniques. This reached statistical significance for lateral bending (P = .031) and medial-lateral translation (P = .030) when compared with the log-roll maneuver. The lift-and-slide technique was significantly more effective at reducing motion than the log roll for axial rotation (P = .029) and lateral bending (P = .006). CONCLUSION: The log roll resulted in the most motion at an unstable cervical injury as compared with the other 2 spine-boarding techniques examined. The 8-person lift and lift-and-slide techniques may both be more effective than the log roll at reducing unwanted cervical spine motion when spine boarding an injured football player. Reduction of such motion is critical in the prevention of iatrogenic injury.

Surgeon-industry conflict of interest: survey of opinions regarding industry-sponsored educational events and surgeon teaching: clinical article.

OBJECT: Conflict of interest (COI) as it applies to medical education and training has become a source of considerable interest, debate, and regulation in the last decade. Companies often pay surgeons as faculty for educational events and often sponsor and give financial support to major professional society meetings. Professional medical societies, industry, and legislators have attempted to regulate potential COI without consideration for public opinion. The practice of evidence-based medicine requires the inclusion of patient opinion along with best available evidence and expert opinion. The primary goal of this study was to assess the opinion of the general population regarding surgeon-industry COI for education-related events. METHODS: A Web-based survey was administered, with special emphasis on the surgeon's role in industry-sponsored education and support of professional societies. A survey was constructed to sample opinions on reimbursement, disclosure, and funding sources for educational events. RESULTS: There were 501 completed surveys available for analysis. More than 90% of respondents believed that industry funding for surgeons' tuition and travel for either industry-sponsored or professional society educational meetings would either not affect the quality of care delivered or would cause it to improve. Similar results were generated for opinions on surgeons being paid by industry to teach other surgeons. Moreover, the majority of respondents believed it was ethical or had no opinion if surgeons had such a relationship with industry. Respondents were also generally in favor of educational conferences for surgeons regardless of funding source. Disclosures of a surgeon-industry relationship, especially if it involves specific devices that may be used in their surgery, appears to be important to respondents. CONCLUSIONS: The vast majority of respondents in this study do not believe that the quality of their care will be diminished due to industry funding of educational events, for surgeon tuition, and/or travel expenses. The results of this study should help form the basis of policy and continued efforts at surgeon-industry COI management.

Surgeon-industry conflict of interest: survey of North Americans' opinions regarding surgeons consulting with industry.

BACKGROUND CONTEXT: Surgeon-industry conflict of interest (COI) has become a source of considerable interest. Professional medical societies, industry, and policy makers have attempted to regulate potential COI without consideration for public opinion. PURPOSE: The objective of this study was to report on the opinions of individuals representing the general public regarding surgeon-industry consulting relationships. STUDY DESIGN/SETTING: Web-based survey. METHODS: Survey was administered using a "spine Web site," and opinions are collected on surgeon-industry consulting and regulation. Associations among responses to similar questions were assessed to ensure validity and subgroup analysis performed for respondent age, sex, education, insurance, employment, and patient status. RESULTS: Six hundred ten of 642 surveys had complete data. The sample population comprised more females and was older and more educated than the American population. About 80% of respondents felt it was ethical and either beneficial or of no influence to the quality of health care if surgeons were consultants for surgical device companies. Most felt disclosure of an industry relationship was important and paying surgeons royalties for devices, other than those they directly implant, would not affect quality of care. Respondents support multidisciplinary surgeon-industry COI regulation and trust doctors and their professional societies to head this effort. CONCLUSIONS: Despite the known potential negative impact of surgeon-industry COI on patient care, this study revealed that this does not seem to be reflected in the opinion of the general public. The respondents felt that disclosure is deemed one of the most important means of self-regulation and COI management, which is in agreement with current trends of most spine societies and journals that are increasing the stringency of disclosure policies.

Accuracy of intraoperative computed tomography-based navigation for placement of percutaneous pedicle screws.

MISS techniques have gained recent popularity. The proposed benefits of these techniques include reduced tissue trauma, reduced blood loss, less perioperative pain, and a quicker recovery and return to normal activities. The purpose of this study was to evaluate the accuracy of intraoperative computed tomography (CT)-based navigation for placement of percutaneous pedicle screws in a cadaveric model. Outcome measures included accuracy of screw placement. Two cadaveric specimens were utilized. CT images were obtained using an O-Arm (Medtronic, Memphis, Tennessee, United States) and were coupled to the Stealth navigation system (Medtronic). Computer navigation was used for placement of percutaneous pedicle screws. Screws were placed bilaterally from T5 to S1. Postinsertion CT scans were obtained. Pedicle breach was assessed and classified (I: none, II: < 2 mm, III: 2 to 4 mm, or IV: > 4 mm) with direction of breach. Thirty thoracic screws were placed with 3 (10%) medial breaches and 17 (56.7%) lateral breaches (grade III). Of 20 lumbar screws there were 0 medial breaches and 2 (10%) lateral breaches (1 grade III, 1 grade IV). Four sacral screws were placed without breaches. The real-time computer-aided navigation tool ("simulated screw") was limited in identifying a breach. Manipulation of the surgeon's hand or driver could change the orientation of the navigation tool without changing the screw trajectory. CT-based navigation for percutaneous pedicle screw placement appears safe for the lumbar spine. Lateral thoracic breaches appeared commonly but were not felt to be clinically significant. The 10% rate of medial thoracic breach was concerning, but definitive conclusions could not be made due to the small sample size.

Estimating the effective radiation dose imparted to patients by intraoperative cone-beam computed tomography in thoracolumbar spinal surgery.

STUDY DESIGN: Observational. OBJECTIVE: To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios. SUMMARY OF BACKGROUND DATA: Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses. METHODS: Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors. RESULTS: Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3. CONCLUSION: We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.