Correction to: Radiation exposure to the surgeon during minimally invasive spine procedures is directly estimated by patient dose.

Unfortunately, the first author surname was incorrectly published as "Harrison Farber" instead of "Farber" in original publication.

Radiation exposure to the surgeon during minimally invasive spine procedures is directly estimated by patient dose.

PURPOSE: Radiation exposure is a necessary component of minimally invasive spine procedures to augment limited visualization of anatomy. The surgeon's exposure to ionizing radiation is not easily recognizable without a digital dosimeter-something few surgeons have access to. The aim of this study was to identify an easy alternative method that uses the available radiation dose data from the C-arm to accurately predict physician exposure. METHODS: The senior surgeon wore a digital dosimeter during all minimally invasive spine fusion procedures performed over a 12-month period. Patient demographics, procedure information, and radiation exposure throughout the procedure were recorded. RESULTS: Fifty-five minimally invasive spine fusions utilizing 330 percutaneous screws were included. Average radiation dose was 0.46 Rad/screw to the patient. Average radiation exposure to the surgeon was 1.06 ± 0.71 µSv/screw, with a strong positive correlation (r = 0.77) to patient dose. The coefficient of determination (r2) was 0.5928, meaning almost two-thirds of the variability in radiation exposure to the surgeon is explained by radiation exposure to the patient. CONCLUSIONS: Intra-operative radiation exposure to the patient, which is easily identifiable as a continuously updated fluoroscopic monitor, is a reliable predictor of radiation exposure to the surgeon during percutaneous screw placement in minimally invasive spinal fusion surgery and therefore can provide an estimate of exposure without the use of a dosimeter. With this, a surgeon can better understand the magnitude of their exposure on a case-by-case basis rather than on a quarterly basis, or more likely, not at all. These slides can be retrieved under Electronic Supplementary Material.

C-arm Positioning Is a Significant Source of Radiation in Spine Surgery.

STUDY DESIGN: Prospective chart review. OBJECTIVE: It is well-known that radiation exposure during minimally invasive spine procedures can be substantial. Less interest has focused on setup radiation exposure before incision, including preoperative images used for surgical approach. The present study seeks to better quantify the significance of setup radiation in the total radiation exposure of minimally invasive spine surgery. SUMMARY OF BACKGROUND DATA: Radiographic localization is necessary in minimally invasive spine procedures to visualize anatomy, but increased radiation exposure is associated with health risks. Preoperative imaging for anatomical localization has not been previously analyzed as an appreciable source of radiation. METHODS: From an institutional review board-approved database of more than 1100 procedures, the minimally invasive spine cases with recorded set-up radiation were extracted. The total radiation, set-up radiation, and procedure type data were evaluated. Statistics were generated using a chi-squared analysis. RESULTS: Set-up and total radiation data were collected for 270 spine surgeries performed by four surgeons at two locations. There were 30 thoracic and 240 thoracolumbar/lumbar cases; 78 anterior and 192 posterior cases. Average total radiation (set-up and intraoperative) was 8.04 rad, and average setup radiation was 1.90 rad (28%, std 2.97 rad) across all cases. On average for the thoracolumbar/lumbar cases, set-up radiation accounted for almost 25% of total radiation with 1.76 rad from setup out of 8.16 rad total. Thoracic-only cases often necessitated even more images for localization, generating an average set-up/total percentage of 52%. Across all procedures, set-up radiation significantly increased the total radiation exposure because it accounted for more than 25% of the total procedure. CONCLUSION: Radiation exposure during preoperative localization can be substantial. Operating room personnel should recognize the high percentage of radiation that occurs during set-up, and merit should be given to techniques and technologies that can limit unnecessary radiation exposure during this portion of the procedure. LEVEL OF EVIDENCE: 2.

Postoperative Spine Dressing Changes Are Unnecessary.

INTRODUCTION: There is minimal literature regarding when dressing changes should be performed. We present the dressing change protocol adopted by our institution. The purpose of this study was to provide an update of our experience with this dressing change protocol over a 15-year period. METHODS: Effective January 2005, we implemented our universal protocol of no dressing changes for five days after surgery. Reviewing a health system administrative database, all spine surgery cases involving instrumentation performed at our institution were captured. Surgical site infection (SSI) cases: superficial, deep, and organ space as defined by the Centers for Disease Control and Prevention (CDC), were identified by reviewing an infection control database. Fisher exact test was used to compare SSI rates in all instrumented fusion cases from January 1999 to December 2004 (prior to implementation of the dressing change protocol) to those from January 2005 to December 2013 (after the protocol was initiated). RESULTS: A total of 8,631 instrumented spine fusions were performed at a single institution from 1999 to 2013. Overall, after instituting our universal no-dressing-change protocol, SSI rates for all cervical, thoracic, and lumbar instrumented cases combined decreased from 3.9% (97/2473) to 0.93% (57/6158) (p < .0001). The reduction in SSI rates was most significant for posterior cervical and posterior lumbar surgeries. After our dressing change protocol was implemented, we saw an improvement in SSI rates for posterior cervical instrumented cases from 3.2% (6/186) to 0.50% (4/815) (p = .0041). Posterior lumbar instrumented fusion SSI rates dropped from 5.5% (65/1179) to 1.1% (32/2890) (p < .0001). CONCLUSION: Dressing changes in the immediate postoperative period are not necessary. Applying a sterile dressing in the operating room may serve as a barrier to nosocomial pathogens during hospitalization. Our data suggest this dressing change protocol may lead to reduced SSI risk. Leaving the original postoperative surgical dressing intact is safe, simple, and cost-effective.

Distal biceps tendon repair: a biomechanical comparison of intact tendon and 2 repair techniques.

BACKGROUND: A variety of techniques have been described for distal biceps tendon reattachment-bone tunnel with transosseous sutures, suture anchors, and interference screw techniques. HYPOTHESIS: There will be no significant difference between the mean failure strength, maximum strength, and stiffness of the intact specimen and repair techniques tested: bone tunnel with transosseous sutures and interference screw. STUDY DESIGN: Controlled laboratory study. METHODS: Nine matched pairs of fresh-frozen human cadaveric elbows were prepared. The intact tendon was pulled from the radial tuberosity; the right and left elbows were randomized to bone tunnels with transosseous sutures or interference screw repair techniques. The repaired specimens were pulled using the same regimen for the intact tendon. Failure strength, maximum strength, and stiffness were measured and compared. RESULTS: The mean failure strength, maximum strength, and stiffness of intact tendons were 204.3 +/- 76.9 N, 221.7 +/- 65.9 N, and 30.1 +/- 12.4 N/mm, respectively; for the interference screw specimens, 178.0 +/- 54.5 N, 192.1 +/- 53.1 N, and 30.4 +/- 9.5 N/mm, respectively; and for the bone tunnel specimens, 124.9 +/- 22.8 N, 206.6 +/- 49.8 N, and 15.9 +/- 5.6 N/mm, respectively. There were no significant differences between measures in the intact and interference screw specimens. Mean failure strength and stiffness of the bone tunnel specimens were significantly lower than those of the intact and interference screw specimens; there was no significant difference between the maximum strengths of the treatments. Interference screw failure occurred abruptly with little plastic deformation in nearly all specimens with the tendon and screw pulling out as a unit, often involving fracture of the radial wall. Two of the bone tunnels failed at the bony bridge; the remainder lost bone-tendon contact as the distal tendon was shredded by the suture. CONCLUSION: The results suggest interference screw fixation repair is nearly as strong and stiff as the intact tendon and stronger than the bone tunnel repair technique. CLINICAL RELEVANCE: The interference screw provides better stiffness and failure strength compared with the bone tunnel technique for distal biceps tendon repair. Given the superior mechanical properties, the interference screw technique is recommended as the treatment of choice for biceps tendon rupture repair.

Percutaneous lumbar pedicle screw placement aided by computer-assisted fluoroscopy-based navigation: perioperative results of a prospective, comparative, multicenter study.

STUDY DESIGN: Institutional review board-approved, prospective, multicenter, comparative study. OBJECTIVE: To assess the accuracy and utility of a computer-assisted fluoroscopic navigation method for percutaneous placement of lumbar pedicle screws compared with conventional fluoroscopic placement. SUMMARY OF BACKGROUND DATA: Recent reports indicate that cortical breaches during percutaneous pedicle screw placement can exceed 15%. Computed tomography (CT)- and fluoroscopy-based navigation systems may facilitate increased placement accuracy with reduced radiation exposure and operative times. METHODS: Patients were alternately assigned to either the Guidance or Control group. The Guidance group underwent lumbar pedicle screw placement using the oblique visualization technique and computer-assisted fluoroscopic navigation. The Control group underwent lumbar pedicle screw placement per standard percutaneous technique aided by fluoroscopy alone. Baseline demographics, visual analog scale (VAS) pain scores, and American Spinal Injury Association scores were obtained preoperatively and in the immediate postoperative period. Fluoroscopy times and guidewire insertion times were recorded intraoperatively. All postoperative CT scans were reviewed by an independent spine surgeon to grade screw placement accuracy. RESULTS: Forty-two patients (210 screws) were assigned to the Guidance group and 34 patients (152 screws) were assigned to the Control group. Use of Guidance resulted in reduced average fluoroscopy usage per pedicle [6.6 sec (SD = 5.1) vs. 9.6 sec (SD 6.2), P < 0.001] and more expedient placement of guidewires per pedicle [3.65 min (SD = 2.31) vs. 4.43 min (SD = 2.56), P = 0.003]. The Guidance group experienced less than half of the breach rate of the Control group (3.0% vs. 7.2%, P = 0.055) and reduced breach magnitudes. None of the breaches resulted in a corresponding neurological deficit or required revision. All patient-reported outcomes were significantly improved after surgery and there were no significant differences in average postoperative VAS scores between treatment groups. CONCLUSION: Use of Guidance reduces fluoroscopy and insertion times with increased accuracy compared with conventional fluoroscopic methods of percutaneous pedicle screw insertion.

Accuracy of percutaneous lumbar pedicle screw placement using the oblique or "owl's-eye" view and novel guidance technology.

OBJECT: This study was conducted to assess the in vivo safety and accuracy of percutaneous lumbar pedicle screw placement using the owl's-eye view of the pedicle axis and a new guidance technology system that facilitates orientation of the C-arm into the appropriate fluoroscopic view and the pedicle cannulation tool in the corresponding trajectory. METHODS: A total of 326 percutaneous pedicle screws were placed from L-3 to S-1 in 85 consecutive adult patients. Placement was performed using simple coaxial imaging of the pedicle with the owl's-eye fluoroscopic view. NeuroVision, a new guidance system using accelerometer technology, helped align the C-arm trajectory into the owl's-eye view and the cannulation tool in the same trajectory. Postoperative fine-cut CT scans were acquired to assess screw position. Medical records were reviewed for complications. RESULTS: Five of 326 screws breached a pedicle cortex­all breaches were less than 2 mm­for an accuracy rate of 98.47%. Five screws violated an adjacent facet joint. All were at the S-1 superior facet and included in a fusion. No screw violated an adjacent mobile facet or disc space. There were no cases of new or worsening neurological symptoms or deficits for an overall clinical accuracy of 100%. CONCLUSIONS: The owl's-eye technique of coaxial pedicle imaging with the C-arm fluoroscopy, facilitated by NeuroVision, is a safe and accurate means by which to place percutaneous pedicle screws for degenerative conditions of the lumbar spine. This is the largest series reported to use the oblique or owl's-eye projection for percutaneous pedicle screw insertion. The accuracy of percutaneous screw insertion with this technique meets or exceeds that of other reported clinical series or techniques.

A novel technique of intra-spinous process injection of PMMA to augment the strength of an inter-spinous process device such as the X STOP.

STUDY DESIGN: Biomechanical. OBJECTIVE: To determine if cement injection into the spinous process will improve compression strength. SUMMARY OF BACKGROUND DATA: The X STOP (St. Francis Medical Technologies) has been shown to be a safe and effective means for decompressing 1- or 2-level lumbar spinal stenosis (LSS). The X STOP is indicated for LSS patients with osteoporosis, but contraindicated for patients with severe osteoporosis. In an attempt to address these LSS patients with demonstrably weaker bone, a technique to strengthen the spinous process with polymethylmethacrylate (PMMA) injection is presented. METHODS: Nine pairs of adjacent fresh frozen cadaveric lumbar vertebrae were DEXA scanned before testing. They were randomly assigned to the PMMA group and a control group. Nine of the specimens were injected with PMMA. Each spinous process was then compressed between 2 X STOPs. The testing model was designed to simulate the loading of a 2-level X STOP placement. The mean load to failure and stiffness values of the treated and untreated groups were calculated. The specimens were inspected carefully for PMMA infiltration and extrusion. RESULTS: The mean bone mineral density (BMD) values of the control and PMMA treatment groups were 0.99 +/- 0.13 g/cm and 0.98 +/- 0.10 g/cm, respectively; P > 0.616. The mean volume of cement injected was 2.2 +/- 0.3 cc. The mean failure load values of the control and PMMA treatment groups were 1250 +/- 627 N and 2386 +/- 1034 N, respectively; P < 0.001. The mean stiffness values of the control and PMMA treatment groups were 296 +/- 139 N/mm and 381 +/- 131 N/mm, respectively; P > 0.059. Most specimens had flow of the cement into the laminae and some into the facet and pedicle. No PMMA was found within the spinal canal. CONCLUSION: This first reported technique of posterior element vertebroplasty may increase the indications and success for patients with decreased BMD who seek an interspinous implant such as the X STOP. A possible role may exist in increasing the effectiveness of such devices. However, clinical trials have yet been performed. These results demonstrate that PMMA injection in the spinous processes is effective in increasing resistance to compressive forces in an X STOP model.