Does the accuracy of pedicle screw placement differ between the attending surgeon and resident in navigated robotic-assisted minimally invasive spine surgery?

Robotic assistance with integrated navigation is an area of high interest for improving the accuracy of minimally invasive pedicle screw placement. This study analyzes the accuracy of pedicle screw placement between an attending spine surgeon and a resident by comparing the left and right sides of the first 101 consecutive cases using navigated robotic assistance in a private practice clinical setting. A retrospective, Institutional Review Board-exempt review of the first 106 navigated robot-assisted spine surgery cases was performed. One attending spine surgeon and one resident performed pedicle screw placement consistently on either the left or right side (researchers were blinded). A CT-based Gertzbein and Robbins system (GRS) was used to classify pedicle screw accuracy, with grade A or B considered accurate. There were 630 consecutive lumbosacral pedicle screws placed. Thirty screws (5 patients) were placed without the robot due to surgeon discretion. Of the 600 pedicle screws inserted by navigated robotic guidance (101 patients), only 1.5% (9/600) were repositioned intraoperatively. Based on the GRS CT-based grading of pedicle breach, 98.67% (296/300) of left-side screws were graded A or B, 1.3% (4/300) were graded C, and 0% (0/300) were graded D. For the right-side screws, 97.67% (293/300) were graded A or B, 1.67% (5/300) were graded C, and 0.66% (2/300) were graded D. This study demonstrated a high level of accuracy (based on GRS) with no significant differences between the left- and right-side pedicle screw placements (98.67% vs. 97.67%, respectively) in the clinical use of navigated, robot-assisted surgery.

Pedicle screw accuracy in clinical utilization of minimally invasive navigated robot-assisted spine surgery.

In the emerging field of robot-assisted spine surgery, the radiographic evaluation of pedicle screw accuracy in clinical application is an area of high interest. This study describes the pedicle screw accuracy of the first 56 consecutive cases in which navigated robotic assistance was used in a private practice clinical setting. A retrospective, Institutional Review Board-exempt review of the first 56 navigated robot-assisted spine surgery cases was performed. Pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. A CT-based Gertzbein and Robbins system (GRS) was used to classify pedicle screw accuracy. In the first 56 robotic cases, 356 total pedicle screws were placed. Eight screws were placed without the robot due to surgeon discretion. Of the 348 pedicle screws inserted by navigated robotic guidance, only 2.6% (9/348) were repositioned, resulting in a 97.4% (339/348) successful screw placement rate. The average age was 64, and 48% were female. Average body mass index was 31 kg/m2. Based on the GRS CT-based grading, 97.7% (340/348) were graded A or B, 1.7% (6/348) screws were graded C, and only 0.6% (2/348) of screws were graded D. Two complications, explantation of interbody and vacuum-assisted wound closure, were reported as requiring a return to the OR, but these were not related to robotic guidance or pedicle screws. This study demonstrated a high level of accuracy (97.7%) in the first 56 cases using navigated, robot-assisted surgery based on the GRS. There were two non-screw-related complications requiring return to the operating room.

Robotic-assisted navigated minimally invasive pedicle screw placement in the first 100 cases at a single institution.

Proper pedicle screw placement is an integral part of spine fusion requiring expertly trained spine surgeons. Advances in medical imaging guidance have improved accuracy. There is high interest in the emerging field of robot-assisted spine surgery; however, safety and accuracy studies are needed. This study describes the pedicle screw placement of the first 100 cases in which navigated robotic assistance was used in a private practice clinical setting. A single-surgeon, single-site retrospective Institutional Review Board-exempt review of the first 100 navigated robot-assisted spine surgery cases was performed. An orthopaedic surgeon evaluated screw placement using plain film radiographs. In addition, pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. Results demonstrated a high level (99%) of successful surgeon assessed pedicle screw placement in minimally invasive navigated robot-assisted spine surgery, with no malpositions requiring return to the OR.

Navigated robot-guided pedicle screws placed successfully in single-position lateral lumbar interbody fusion.

Minimally invasive lateral interbody fusion has distinct advantages over traditional posterior approaches. When posterior stabilization is needed, percutaneous placement of pedicle screws from the lateral decubitus position may potentially increase safety and improve operative efficiency by precluding the need for repositioning. However, safe placement of pedicle screws in the lateral position remains technically challenging. This study describes the pedicle screw placement of single-position lateral lumbar interbody fusion (SP-LLIF) cases in which navigated robotic assistance was used. A single-surgeon, single-site, retrospective Institutional Review Board-exempt review of the first 55 SP-LLIF navigated robot-assisted spine surgery cases performed by the lead author was conducted. An orthopaedic surgeon evaluated screw placement using plain film radiographs. In addition, pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. In the first 55 SP-LLIF cases, 342 pedicle screws were placed. The average patient age and body mass index were 67 years and 29.5 kg/m2, respectively. Of the 342 screws placed, 4% (14/342) were placed manually without the robot, due to surgeon discretion. Of the 328 screws placed with the robot, 2% (7/328) were repositioned based on the surgeon's discretion, resulting in a 98% navigated robot-assisted pedicle screw placement success rate. In this cohort there were no revisions due to malpositioned screws. No complications due to screw placement were reported. This study demonstrates a high level (98%) of successful surgeon-assessed pedicle screw placement in minimally invasive navigated robot-assisted SP-LLIF, with no malpositions requiring a return to the OR.

Navigated robotic assistance improves pedicle screw accuracy in minimally invasive surgery of the lumbosacral spine: 600 pedicle screws in a single institution.

BACKGROUND: In the emerging field of robot-assisted spine surgery, radiographic evaluation of pedicle screw accuracy in the surgical setting is of high interest. Advances in medical imaging have improved the accuracy of pedicle screw placement, from fluoroscopy-guided to computer-aided navigation. METHODS: A retrospective, institutional review board-exempt review of the first 106 navigated robot-assisted spine surgery cases was performed. Radiographic evaluation of preoperative and postoperative computerized tomography (CT) scans were collected. RESULTS: In the first 106 cases, 630 lumbosacral pedicle screws were placed. Thirty screws were placed in five patients without the robot because of surgeon discretion. Of the 600 pedicle screws inserted by navigated robotic guidance, only 1.5% (9/600) were repositioned intraoperatively. CONCLUSION: This study demonstrated a high level of accuracy (98.2%) in terms of grade A or B pedicle screw breach scores in the clinical use of navigated, robot-assisted surgery in its first 101 cases.

What Are the Indications for Spinal Fusion Surgery in Scheuermann Kyphosis?

BACKGROUND: Surgical indications for Scheuermann kyphosis are variable. We sought to evaluate the characteristics of patients undergoing operative versus nonoperative treatment of Scheuermann kyphosis to better understand current practices and the factors which contribute to the decision for surgical management. METHODS: Multicenter prospective cohort study. We evaluated consecutive patients presenting with Scheuermann kyphosis. Patients underwent either surgical or nonoperative management according to surgeon and patient discretion. Preoperative patient-reported outcome measures (Scoliosis Research Society and Spinal Appearance Questionnaire scores), demographics, and radiographic characteristics were assessed. RESULTS: Overall, 150 patients with Scheuermann kyphosis were enrolled, with 77 choosing nonoperative treatment and 73 treated operatively. Compared with the nonoperative cohort, patients treated operatively were older (16.3±2.0 vs. 15.1±2.2, P=0.0004), and had higher body mass index (26.3±7.2 vs. 22.7±6.5, P=0.003), had greater T2-T12 kyphosis (71±14 degrees vs. 61±12 degrees, P<0.001), increased pelvic incidence (46 vs. 41 degrees, P=0.03) and pelvic tilt (10 vs. 3 degrees, P=0.03). There was no detected difference in maximal sagittal Cobb angle in the operative versus nonoperative patients (73±11 vs. 70±12 degrees, P=0.11). Functionally, the operative patients had worse Scoliosis Research Society pain scores (3.7±0.9 vs. 4.1±0.7, P=0.0027) and appearance scores (2.9±0.7 vs. 3.4±0.8, P <0.0001). CONCLUSIONS: Patients undergoing surgical management of Scheuermann disease were more likely to have large body mass index and worse pain scores. Other factors beyond radiographic measurement likely contribute to the decision for surgical management of Scheuermann kyphosis. LEVEL OF EVIDENCE: Level II.

Oswestry Disability Index: Is Telephone Administration Valid?

Background: The Oswestry Disability Index (ODI) is among the most widely used patient reported outcome measures for the assessment of spinal conditions. Traditionally, the ODI has been administered in outpatient clinics on a face-to-face basis, which can be expensive and time consuming. Furthermore, the percentage of patients lost to clinical follow-up is high, particularly after 2-5 years. Thus, telephonic administration of the ODI, if valid, could be a convenient way of capturing patient outcomes and increasing follow-up rates. The objective of this study was to validate telephonic administration of the ODI compared to face-to-face administration. Methods: A convenience sample of individuals with and without back pain in an academic medical center were recruited for this study. Face-to-face administration of the ODI was completed and retested 24 hours later via phone. Test-retest reliability was determined by calculating the intraclass correlation coefficient. Results: 22 individuals completed the ODI questionnaire face-to-face, then via telephone 24 hours later. There was a mean 2% (± 3) intra-rater ODI score difference (range: 0% to 12%). The intraclass correlation coefficient overall was 0.98 (95% CI: 0.96, 0.99, p<0.001) with a range of 0.95 to 1.0, revealing near-perfect test-retest reliability. Conclusions: Administration of the ODI questionnaire over the phone has excellent test-retest reliability when compared to face-to-face administration. Telephone administration is a convenient and reliable option for obtaining follow-up outcomes data. Clinical Relevance: Telephonic administration of the ODI is scientifically valid, and should be an accepted method of data collection for state-level and national-level outcomes projects.

Which Malpositioned Pedicle Screws Should Be Revised?

BACKGROUND: Up to 10% of free-hand pedicle screws are malpositioned, and 1 in 300 patients may undergo return to surgery for revision of malpositioned screws. The indications for revision of asymptomatic malpositioned screws have not been carefully examined in the literature. We sought to evaluate the threshold among spinal deformity surgeons for revision of malpositioned screws. METHODS: Twelve experienced spine surgeons reviewed x-ray and computed tomographic images of 32 malpositioned pedicle screws with variable degrees of anterior, medial, and lateral breeches. The surgeons were asked whether based on the image they would revise the screw: (1) intraoperatively before rod placement; (2) intraoperatively after rod placement; (3) in clinic with an asymptomatic patient. For each scenario, we assumed stable neuromonitoring and no neurological changes. Agreement and multirater κ was calculated. RESULTS: There was good agreement as to which screws were malpositioned (80% agreement, κ=0.703). After the rod was placed or postoperatively (scenarios 2 and 3), surgeons less frequently recommended screw revision, and there was greater variability among the surgeons' recommendations. For return to surgery from clinic for asymptomatic screw revision, % agreement was only 65% (κ=0.477). The majority recommended revision surgery for screws which approached the dura (10/12) or the aorta (7/12 surgeons). Half of the surgeons recommended revision surgery for an asymptomatic screw if the entire screw diameter was in the canal. Revision surgery was not recommended for asymptomatic patients with screws partially violating the canal (<½ the screw diameter), malpositioned laterally in the rib head, or with small anterior cortical violations remote from a vascular structure. CONCLUSIONS: There is significant variability of opinion among surgeons regarding which malpositioned screws can be safely observed in an asymptomatic patient. Given the frequency of malpositioned screws and morbidity of surgical return to surgery, more long-term data are needed to develop practice guidelines for determining which screws require revision surgery. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Implant Density at the Apex Is More Important Than Overall Implant Density for 3D Correction in Thoracic Adolescent Idiopathic Scoliosis Using Rod Derotation and En Bloc Vertebral Derotation Technique.

STUDY DESIGN: Biomechanical analysis of 3D correction and bone-screw forces through numerical simulations of scoliosis instrumentation with different pedicle screw patterns. OBJECTIVE: To analyze the effect of different screw densities and distributions on 3D correction and bone-screw forces in adolescent idiopathic scoliosis (AIS) instrumentation. SUMMARY OF BACKGROUND DATA: Instrumentation constructs with various numbers of pedicle screws and patterns have been proposed for thoracic AIS instrumentation. However, systematic biomechanical studies have not yet been completed on the appropriate screw patterns for optimal 3D correction. METHODS: Patient-specific biomechanical models of the spine were created for 10 AIS cases (Lenke 1). For each case, surgical instrumentation patterns were computationally simulated using respectively a reference screw pattern (two screws per level fused) and six alternative screw patterns with fewer screws. Simulated surgical maneuvers and model definition were unchanged between simulations except the number and distribution of screws. 3D correction and bone-screw forces were compared. RESULTS: A total of 140 posterior instrumentations were computationally simulated. Mean corrections in the coronal and sagittal planes with alternative screw patterns were within 4° to the reference pattern. Increasing screw density in the apical region from one to two screws per level improved percent apical vertebral rotation (AVR) correction (r = 0.887, P < 0.05). Average bone-screw force associated with the reference screw pattern was 243N ±â€Š54N and those with the alternative screw patterns were 11% to 48% lower. CONCLUSION: Compared with the reference maximal screw density pattern, alternative screw patterns allowed similar corrections in the coronal and sagittal planes. AVR correction was strongly correlated with screw density in the apical region; AVR correction varied significantly with screw patterns of the same overall screw density when an en bloc vertebral derotation technique was simulated. High screw density tended to overconstrain the instrumented spine and resulted in higher forces at the bone-screw interface. LEVEL OF EVIDENCE: N/A.

Current Evidence Regarding the Treatment of Pediatric Lumbar Spondylolisthesis: A Report From the Scoliosis Research Society Evidence Based Medicine Committee.

STUDY DESIGN: Structured literature review. OBJECTIVES: The Scoliosis Research Society requested an assessment of the current state of peer-reviewed evidence regarding pediatric lumbar spondylolisthesis to identify what is known and what research remains essential to further understanding. SUMMARY OF BACKGROUND DATA: Pediatric lumbar spondylolisthesis is common, yet no formal synthesis of the published literature regarding treatment has been previously performed. METHODS: A comprehensive literature search was performed. From 6600 initial citations with abstract, 663 articles underwent full-text review. The best available evidence regarding surgical and medical/interventional treatment was provided by 51 studies. None of the studies were graded Level I or II evidence. Eighteen of the studies were Level III, representing the current best available evidence. Thirty-three of the studies were Level IV. RESULTS: Although studies suggest a benign course for "low grade" (<50% slip) isthmic spondylolisthesis, extensive literature suggests that a substantial number of patients present for treatment with pain and activity limitations. Pain resolution and return to activity is common with both medical/interventional and operative treatment. The role of medical/interventional bracing is not well established. Uninstrumented posterolateral fusion has been reported to produce good clinical results, but concerns regarding nonunion exist. Risk of slip progression is a specific concern in the "high grade" or dysplastic type. Although medical/interventional observation has been reported to be reasonable in a small series of asymptomatic high-grade slip patients, surgical treatment is commonly recommended to prevent progression. There is Level III evidence that instrumentation and reduction lowers the risk of nonunion, and that circumferential fusion is superior to posterior-only or anterior-only fusion. There is Level III evidence that patients with a higher slip angle are more likely to fail medical/interventional treatment of high-grade spondylolisthesis. CONCLUSIONS: The current "best available" evidence to guide the treatment of pediatric spondylolisthesis is presented. LEVEL OF EVIDENCE: Level III; review of Level III studies.

Biomechanical effect of pedicle screw distribution in AIS instrumentation using a segmental translation technique: computer modeling and simulation.

BACKGROUND: Efforts to select the appropriate number of implants in adolescent idiopathic scoliosis (AIS) instrumentation are hampered by a lack of biomechanical studies. The objective was to biomechanically evaluate screw density at different regions in the curve for AIS correction to test the hypothesis that alternative screw patterns do not compromise anticipated correction in AIS when using a segmental translation technique. METHODS: Instrumentation simulations were computationally performed for 10 AIS cases. We simulated simultaneous concave and convex segmental translation for a reference screw pattern (bilateral polyaxial pedicle screws with dorsal height adjustability at every level fused) and four alternative patterns; screws were dropped respectively on convex or concave side at alternate levels or at the periapical levels (21 to 25% fewer screws). Predicted deformity correction and screw forces were compared. RESULTS: Final simulated Cobb angle differences with the alternative screw patterns varied between 1° to 5° (39 simulations) and 8° (1 simulation) compared to the reference maximal density screw pattern. Thoracic kyphosis and apical vertebral rotation were within 2° of the reference screw pattern. Screw forces were 76 ± 43 N, 96 ± 58 N, 90 ± 54 N, 82 ± 33 N, and 79 ± 42 N, respectively, for the reference screw pattern and screw dropouts at convex alternate levels, concave alternate levels, convex periapical levels, and concave periapical levels. Bone-screw forces for the alternative patterns were higher than the reference pattern (p < 0.0003). There was no statistical bone-screw force difference between convex and concave alternate dropouts and between convex and concave periapical dropouts (p > 0.28). Alternate dropout screw forces were higher than periapical dropouts (p < 0.05). CONCLUSIONS: Using a simultaneous segmental translation technique, deformity correction can be achieved with 23% fewer screws than maximal density screw pattern, but resulted in 25% higher bone-screw forces. Screw dropouts could be either on the convex side or on the concave side at alternate levels or at periapical levels. Periapical screw dropouts may more likely result in lower bone-screw force increase than alternate level screw dropouts.

Current Evidence Regarding Diagnostic Imaging Methods for Pediatric Lumbar Spondylolysis: A Report From the Scoliosis Research Society Evidence-Based Medicine Committee.

BACKGROUND: Spondylolysis is common among the pediatric population, yet no formal systematic literature review regarding diagnostic imaging has been performed. The Scoliosis Research Society (SRS) requested an assessment of the current state of peer reviewed evidence regarding pediatric spondylolysis. METHODS: Literature was searched professionally and citations retrieved. Abstracts were reviewed and analyzed by the SRS Evidence-Based Medicine Committee. Level I studies were considered to provide Good Evidence for the clinical question. Level II or III studies were considered Fair Evidence. Level IV studies were considered Poor Evidence. From 947 abstracts, 383 full texts reviewed. Best available evidence for the questions of diagnostic methods was provided by 27 studies: no Level I sensitivity/specificity studies, five Level II and two Level III evidence, and 19 Level IV evidence. RESULTS: Pain with hyperextension in athletes is the most widely reported finding in history and physical examination. Plain radiography is considered a first-line diagnostic test for suspected spondylolysis, but validation evidence is lacking. There is consistent Level II and III evidence that pars defects are detected by advanced imaging in 32% to 44% of adolescents with spondylolysis based on history and physical. Level III evidence that single-photon emission computed tomography (SPECT) is superior to planar bone scan and plain radiographs but limited by high rates of false-positive and false-negative results and by high radiation dose. Computed tomography (CT) is considered the gold standard and most accurate modality for detecting the bony defect and assessment of osseous healing but exposes the pediatric patient to ionizing radiation. Magnetic resonance imaging (MRI) is reported to be as accurate as CT and useful in detecting early stress reactions of the pars without a fracture. CONCLUSION: Plain radiographs are widely used as screening tools for pediatric spondylolysis. CT scan is considered the gold standard but exposes the patient to a significant amount of ionizing radiation. Evidence is fair and promising that MRI is comparable to CT.

Adolescent Idiopathic Scoliosis Thoracic Volume Modeling: The Effect of Surgical Correction.

BACKGROUND: Scoliosis has been shown to have detrimental effects on pulmonary function, traditionally measured by pulmonary function tests, which is theorized to be correlated to the distortion of the spine and thorax. The changes in thoracic volume with surgical correction have not been well quantified. This study seeks to define the effect of surgical correction on thoracic volume in patients with adolescent idiopathic scoliosis. METHODS: Images were obtained from adolescents with idiopathic scoliosis enrolled in a multicenter database (Prospective Pediatric Scoliosis Study). A convenience sample of patients with Lenke type 1 curves with a complete data set meeting specific parameters was used. Blender v2.63a software was used to construct a 3-dimensional (3D) computational model of the spine from 2-dimensional calibrated radiographs. To accomplish this, the 3D thorax model was deformed to match the calibrated radiographs. The thorax volume was then calculated in cubic centimeters using Mimics v15 software. RESULTS: The results using this computational modeling technique demonstrated that surgical correction resulted in decreased curve measurement as determined by Cobb method, and increased postoperative thoracic volume as expected. Thoracic volume significantly increased by a mean of 567 mm (P<0.001). The percent change in thoracic volume after surgical correction averaged 40% (range, 3% to 87%). The smaller the baseline volume, the greater the change in volume postoperatively (r=-0.86).Evaluation of postoperative data demonstrated that spinal curve measurement as determined by Cobb method was significantly reduced from a mean of 69 degrees (range, 50 to 96 degrees) preoperatively to 27 degrees (range, 13 to 33 degrees) postoperatively (P<0.001). CONCLUSIONS: This pilot study demonstrates methodologic plausibility for measuring 3D changes in thoracic volumes using 2-dimensional imaging. This is an assessment of the novel modeling technique, to be used in larger future studies to assess clinical significance. LEVEL OF EVIDENCE: Level 3-retrospective comparison of prospectively collected data.

Sacral bone mineral density (BMD) assessment using opportunistic CT scans.

This study seeks to establish a method for opportunistic evaluation of sacral bone mineral density. This is a retrospective review of 109 scans from 109 patients who had renal-protocol computed tomography (CT) scans performed for any indication during a 3-month period at a single academic institution in 2014. In the collected CT scans, sacral CT-attenuation in multiple regions of interest (ROI) was compared to the L1 CT-attenuation, an internal reference standard, to determine if a correlation existed. The sacral ROI were analyzed to determine regions of higher and lower attenuation. All sacral ROI had strong correlations with lumbar spine attenuation values, and these values became even stronger when transitional vertebrae were excluded. Sacral attenuation values varied predictably by location, and matched relationships were shown by prior volumetric bone mineral density studies. We conclude that sacral CT-attenuation can be used in opportunistic CT scans to determine sacral bone mineral density. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:160-166, 2017.

Reliability of the Planned Pedicle Screw Trajectory versus the Actual Pedicle Screw Trajectory using Intra-operative 3D CT and Image Guidance.

BACKGROUND: Technological advances, including navigation, have been made to improve safety and accuracy of pedicle screw fixation. We evaluated the accuracy of the virtual screw placement (Stealth projection) compared to actual screw placement (intra-operative O-Arm) and examined for differences based on the distance from the reference frame. METHODS: A retrospective evaluation of prospectively collected data was conducted from January 2013 to September 2013. We evaluated thoracic and lumbosacral pedicle screws placed using intraoperative O-arm and Stealth navigation by obtaining virtual screw projections and intraoperative O-arm images after screw placement. The screw trajectory angle to the midsagittal line and superior endplate was compared in the axial and sagittal views, respectively. Percent error and paired t-test statistics were then performed. RESULTS: Thirty-one patients with 240 pedicle screws were analyzed. The mean angular difference between the virtual and actual image in all screws was 2.17° ± 2.20° on axial images and 2.16° ± 2.24° on sagittal images. There was excellent agreement between actual and virtual pedicle screw trajectories in the axial and sagittal plane with ICC = 0.99 (95%CI: 0.992-0.995) (p<0.001) and ICC= 0.81 (95%CI: 0.759-0.855) (p<0.001) respectively. When comparing thoracic and lumbar screws, there was a significant difference in the sagittal angulation between the two distributions. No statistical differences were found distance from the reference frame. CONCLUSION: The virtual projection view is clinically accurate compared to the actual placement on intra-operative CT in both the axial and sagittal views. There is slight imprecision (~2°) in the axial and sagittal planes and a minor difference in the sagittal thoracic and lumbar angulation, although these did not affect clinical outcomes. In general, we find that pedicle screw placement using intraoperative cone beam CT and navigation to be accurate and reliable, and as such have made it a routine part of our spine practice. This study was approved by the University of Minnesota IRB (#1303E30544).

Accuracy of Pedicle Screw Placement in Children 10 Years or Younger Using Navigation and Intraoperative CT.

STUDY DESIGN: A consecutive case series. OBJECTIVE: To determine the revision rate for pedicle screws placed using intraoperative CT and image-guided navigation in children 10 years or younger. SUMMARY OF BACKGROUND DATA: Screws are frequently used for spinal instrumentation in young children, although this is only by physician-directed use. This is a multicenter retrospective study of patients aged 10 years or younger, who underwent spinal screw instrumentation with image-guided navigation. We hypothesized that intraoperative navigation would result in a high rate of accuracy for screw placement. METHODS: Between 2007 and 2013, 130 pedicle and 7 lateral mass screws were placed in 16 consecutive patients undergoing a total of 17 surgeries at 2 institutions. Mean age at surgery was 6.9 years (range, 0.8-10.9 y). Screws were placed using an open technique with intraoperative CT (O-arm) and image-guided navigation (Stealth). Procedures included: growing spine device (3), hemivertebrae excision (4), posterior fusion (7), cervical fusion (2), and vertebral column resection (1). Congenital deformity was the most common diagnosis. Primary outcome measures were need for intraoperative screw revision or complication associated with screw placement. RESULTS: Mean number of screws used per procedure was 8.1 (range, 2-17). Screws were placed from C1 to L5. Of the 137 screws, 3 required revision to shorter screws for an overall accuracy rate of 97.8%. In 1 case, a right T3 screw was revised due to anterior penetration. In another case, left-sided T1 and T2 pedicle screws were shortened 5 mm because they had penetrated the anterior aspect of their respective vertebral bodies. There were no screw-related complications. CONCLUSIONS: In this series, image-guided navigation resulted in accurate placement of screws in patients aged 10 years or younger with no associated intraoperative complications. The navigated accuracy rate (97.8%) is significantly higher (P=0.01) than the reported 90.9% pedicle screw accuracy rate without navigation in the same age group by Baghdadi and colleagues. Intraoperative CT and image guidance were useful in our practice for placement of screws in skeletally immature patients.

What would be the annual cost savings if fewer screws were used in adolescent idiopathic scoliosis treatment in the US?

OBJECTIVE: There is substantial heterogeneity in the number of screws used per level fused in adolescent idiopathic scoliosis (AIS) surgery. Assuming equivalent clinical outcomes, the potential cost savings of using fewer pedicle screws were estimated using a medical decision model with sensitivity analysis. METHODS: Descriptive analyses explored the annual costs for 5710 AIS inpatient stays using discharge data from the 2009 Kids' Inpatient Database (Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality), which is a national all-payer inpatient database. Patients between 10 and 17 years of age were identified using the ICD-9-CM code for idiopathic scoliosis (737.30). All inpatient stays were assumed to represent 10-level fusions with pedicle screws for AIS. High screw density was defined at 1.8 screws per level fused, and the standard screw density was defined as 1.48 screws per level fused. The surgical return for screw malposition was set at $23,762. A sensitivity analysis was performed by varying the cost per screw ($600-$1000) and the rate of surgical revisions for screw malposition (0.117%-0.483% of screws; 0.8%-4.3% of patients). The reported outcomes include estimated prevented malpositioned screws (set at 5.1%), averted revision surgeries, and annual cost savings in 2009 US dollars, assuming similar clinical outcomes (rates of complications, revision) using a standard- versus high-density pattern. RESULTS: The total annual costs for 5710 AIS hospital stays was $278 million ($48,900 per patient). Substituting a high for a standard screw density yields 3.2 fewer screws implanted per patient, with 932 malpositioned screws prevented and 21 to 88 revision surgeries for implant malposition averted, and a potential annual cost savings of $11 million to $20 million (4%-7% reduction in the total cost of AIS hospitalizations). CONCLUSIONS: Reducing the number of screws used in scoliosis surgery could potentially decrease national AIS hospitalization costs by up to 7%, which may improve the safety and efficiency of care. However, such a screw construct must first be proven safe and effective.

How Much Work Effort is Involved in Minimally Invasive Sacroiliac Joint Fusion?

BACKGROUND: Minimally invasive sacroiliac joint fusion is increasing significantly. Starting January 1, 2015, it has a category I CPT code. The current RVU for this procedure is not equal to the amount of work involved. There is not a published RUC validated survey to establish the work effort of MI SI fusion. Our hospital system has been doing this procedure for 4 years and has been tracking surgeon time through a commercial tracking system (Navicare). Our study looks at time utilization for performance of MI SI joint fusion and a comparator of primary lumbar discectomy (PLD), presumably similar in time and work effort. METHODS: This study was a retrospective review of prospectively collected data using Navicare. The data for 3 surgeons who perform MI SI joint fusion and lumbar discectomies from January 1, 2013 through November 30, 2014 was retrieved. Surgeon room time was identified as the time the patient entered the OR to the time they exited the OR. This was used as opposed to skin to skin time seen in similar studies as it was more accurately and consistently recorded in the medical record. Mean and standard deviations were then compared using student's t-test. RESULTS: In 50 primary MI SI joint fusions, the average in-room time was 112 minutes (SD=23). In 89 cases of PLD, the average in-room time was 119 minutes (SD=26). When comparing mean in-room times, MI SI and PLD were not statistically significantly different (p=0.135, 2-tailed t-test). Post-operative work effort was found to be greater for MI SI joint fusion than PLD. CONCLUSIONS / LEVEL OF EVIDENCE: Surgical time was found to be comparable between MI SI joint fusion and PLD, while work effort was found to be greater for MI SI joint fusion. This signifies at a minimum an equal RVU for PLD should be used for MI SI joint fusion. This study was approved by the Institutional Review Board at the University of Minnesota. LEVEL OF EVIDENCE: 3.

Current Evidence Regarding the Surgical and Nonsurgical Treatment of Pediatric Lumbar Spondylolysis: A Report from the Scoliosis Research Society Evidence-Based Medicine Committee.

STUDY DESIGN: Structured literature review. OBJECTIVES: The Scoliosis Research Society requested an assessment of the current state of peer-reviewed evidence regarding pediatric spondylolysis with the goal of identifying both what is really known and what research remains essential to further understanding. SUMMARY OF BACKGROUND DATA: Spondylolysis is common among children and adolescents and no formal synthesis of the published literature regarding treatment has been previously performed. METHODS: A comprehensive literature search was performed. The researchers reviewed abstracts and analyzed by committee data from included studies. From 947 initial citations with abstract, 383 articles underwent full text review. The best available evidence for clinical questions regarding surgical and nonsurgical treatment was provided by 58 included studies. None of the studies were graded as level I or level II evidence. Two of the studies were graded as level III evidence. Fifty-six of the studies were graded as level IV evidence. No level V (expert opinion) studies were included in the final list. RESULTS: Although natural history studies suggest a benign, relatively asymptomatic course for spondylolysis in most patients, both nonsurgical and surgical treatment series suggest that a substantial number of patients present with pain and activity limitations attributed to spondylolysis. Pain resolution and return to activity are common with both nonsurgical and surgical treatment (80% to 85%, respectively). Although it is implied that most surgically treated patients have failed nonsurgical treatment, the specific treatment modalities and duration required before failure is declared are not well defined. There is insufficient evidence to know which patients will benefit from specific treatment modalities (both nonsurgical and surgical). CONCLUSIONS: Because of the preponderance of uncontrolled case series and the lack of comparative studies, only low-quality evidence is available to guide the treatment of pediatric spondylolysis.

Current Evidence Regarding the Etiology, Prevalence, Natural History, and Prognosis of Pediatric Lumbar Spondylolysis: A Report from the Scoliosis Research Society Evidence-Based Medicine Committee.

STUDY DESIGN: Structured literature review. OBJECTIVES: To assess the current state of evidence as a first step in the development of practice guidelines for pediatric spondylolysis. SUMMARY OF BACKGROUND DATA: Progress in published medical knowledge, changes in societal expectations, and developments in health care economics have led medical organizations to develop evidence-based documents and products. METHODS: A comprehensive literature search for pediatric spondylolysis was performed with the assistance of a medical librarian. The authors reviewed citations and abstracts. Abstracts were reviewed for exclusions and data from included studies were analyzed by committee. A total of 44 articles provided the best available evidence for the questions of etiology, prevalence, natural history, and prognosis: 9 were graded as level I evidence, 23 were level II, 3 were level III, and 9 were level IV. No level V studies were included in the final list. RESULTS: There is good evidence that pediatric lumbar spondylolysis is an acquired fracture of the pars interarticularis that can occur unilaterally or bilaterally. Evidence shows that when chronic, bilateral pars defects develop, 43% to 74% of patients will progress to grade 1 or 2 spondylolisthesis. In addition, unilateral, incomplete, and early lesions can obtain bony union. With or without bony union or spondylolisthesis, short-term symptom resolution is the norm. Long-term prognosis is less clear, but there is fair evidence that most patients will have lumbar symptoms compared with the general population. There is also fair evidence that some patients will develop significant symptoms as adults and will undergo surgical treatment. There is insufficient knowledge to predict which patients will continue to do well in the long term with conservative or no treatment and which patients will develop symptoms significant enough to warrant early intervention. CONCLUSIONS: The current medical literature provides fair to good evidence for clinically relevant questions regarding the etiology, prevalence, natural history, and prognosis of pediatric spondylolysis.