Alternative Uses of O-Arm and Stealth Navigation Technology Over 10 Years: The University of Colorado Experience.

Intraoperative computed tomography scanning with O-arm and use of Stealth navigation can improve surgical outcomes in a variety of orthopedic subspecialties. In spine surgery, the accuracy, precision, and safety of pedicle screw and interbody implant placement has improved. This technology is now routinely used in percutaneous pedicle screw placement and minimally invasive sacroiliac joint fusion. Other applications include, but are not limited to, isthmic pars defect repair, lumbosacral pseudoarticulation resection in Bertolotti's syndrome, radiofrequency ablation, and en bloc tumor resection. Intraoperative navigation has numerous applications, and use of this technology should continue to evolve as the technology advances. [Orthopedics. 2023;46(2):e89-e97.].

Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors.

OBJECTIVE: There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS: Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS: Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS: Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.

Blockade of Osteoclast-Mediated Bone Resorption With a RANKL-Inhibitor Enhances Bone Formation in a Rat Spinal Fusion Model.

STUDY DESIGN: Rat spine fusion model. OBJECTIVE: The present study aimed to determine whether administration of osteoprotegerin (OPG) in a rat model of spinal fusion increases bone volume, bone density, and decreases osteoclasts in the fusion mass. SUMMARY OF BACKGROUND DATA: OPG is a soluble RANK-ligand inhibitor that blocks osteoclast differentiation and activation. This makes it a potential agent to control the remodeling process and enhance bone mass during spinal fusion. MATERIALS AND METHODS: Forty-eight male Sprague-Dawley rats received a one-level spinal fusion of L4-L5 with bone allograft. Rats were then divided into four groups according to initiation of treatment: (1) saline on day 0 (saline), (2) OPG on day 0 (OPG D0), (3) OPG on day 10 (OPG D10), and (4) OPG on day 21 (OPG D21) postsurgery. After their initial injection, rats received weekly subcutaneous injections of OPG (10 mg/kg) and were euthanized six weeks postsurgery. MicroCT analysis of the fusion site and histological analysis of bone surface for quantification of osteoclast lining was performed. RESULTS: Increased bone volume in the fusion site and around the spinous process was seen in OPG D0 and OPG D10 when compared with saline. Mean trabecular thickness was greater in all groups receiving OPG compared with saline, with OPG D0 and OPG D10 having significantly greater mean trabecular thickness than OPG D21. All OPG groups had less bone surface lined with osteoclasts when compared with Saline, with OPG D0 and OPG D10 having fewer than OPG D21. CONCLUSIONS: This study indicates that OPG inhibited osteoclast bone resorption, which led to greater bone at the fusion site. Future studies investigating OPG on its own or in combination with an osteogenic factor to improve spinal fusion outcomes are warranted to further elucidate its potential therapeutic effect.

Pre-Operative Planning in Complex Deformities and Use of Patient-Specific UNiD™ Instrumentation.

STUDY DESIGN: Review of current literature and authors experience. OBJECTIVE: Pre-operative planning is an integral part of complex spine surgery. With the advent of computer-assisted planning, multiple surgical plans can be evaluated utilizing alignment parameters, and the best plan for individual patients selected. However, the ability to evaluate and measure surgical correction goals intraoperatively are still limited. The use of patient-specific UNiD rods, created based on pre-operative plans, provided an initial tool for implementation of pre-operative plans in the operative setting. METHODS: A literature review for the use of patient-specific UNiD rods in thoracolumbar spine complex surgery was performed. The articles were selected and reviewed for the initial experience/outcomes of these techniques. Further, the initial experience of the authors at The University of Colorado is described. RESULTS: The use of UNiD patient-specific rods, in combination with pre-operative planning has been shown to provide a higher rate of patients with spinopelvic alignment parameters within currently accepted ranges. This includes improvement of sagittal vertical axis (SVA) < 50 mm and pelvic incidence (PI)-lumbar lordosis (LL) = ± 10°. Multiple authors have shown improvement in pelvic tilt to age adjusted values but note continued difficulties in obtaining correction goals. CONCLUSIONS: The use of pre-operative planning software and UNiD patient-specific rods has been shown to improve surgeon's ability to achieve spinopelvic alignment parameters, specifically SVA and PI-LL, along with other possible benefits. Further research is needed regarding long-term value of the technology.

Postoperative pelvic incidence (PI) change may impact sagittal spinopelvic alignment (SSA) after instrumented surgical correction of adult spine deformity (ASD).

OBJECTIVES: To study factors causing postoperative change of PI after surgical correction of ASD and to assess the effect of this variability on postoperative PI-LL mismatch. BACKGROUND: PI is used as an individual constant to define lumbar lordosis (LL) correction goal (PI-LL < 10). Postoperative changes of PI were shown but with opposite vectors. The impact of the PI variability on the postoperative PI-LL has not been studied. METHODS: The medical and radiographic data analyzed for patients who underwent long posterior instrumented spinal fusion. Inclusion criteria are age, ≥ 20 years old; ASD due to degenerative disk disease (DDD) or scoliosis (DS); ≥ 3 levels fused; and 2-year follow-up or revision. Studied parameters are LL (L1-S1), PI, sacral slope (SS), pelvic tilt (PT), and PI-LL. Measurement error and postoperative changes were defined. Statistical analysis includes ANOVA, correlation, regression, and risk assessment by odds ratio; P ≤ 0.05 considered statistically significant. RESULTS: Eighty patients were included: mean age, 62.4 years-old (SD, 11.1); female, 63.7%; mean body mass index (BMI), 27.1 (SD, 5.6). Distribution of patients by follow-ups includes preoperative 100%; postoperative (1-3 weeks), 100%; 11-13 months. 90%; 22-26 months, 58%; and revision: 24%. Pre- versus postoperative PI (∆PI) changed both positively and negatively and the absolute value of change|∆PI| exceeded measurement error (P ≤ 0.05) reaching as high as 31°, and progressed with time; R2 dropped from 0.73 to 0.45 (P < 0.001); ∆PI depended on disproportional changes of SS and PT, preoperative PI, and change of LL. Obesity, DS, and absence of sacroiliac fixation increased |∆PI|. The risk of LL insufficient correction (PI-LL > 10°) associated with a |∆PI|> 6°, P = 0.05. Sacroiliac fixation diminished PI variability only during the first postoperative year. CONCLUSION: Preoperative variability and postoperative instability of PI diminish the applicability of the PI-LL < 10° goal to plan correction of LL. An alternative method is offered. LEVEL OF EVIDENCE: IV.

The Prevalence of the Use of MIS Techniques in the Treatment of Adult Spinal Deformity (ASD) Amongst Members of the Scoliosis Research Society (SRS) in 2016.

STUDY DESIGN: Electronic survey administered to Scoliosis Research Society members. OBJECTIVE: To determine the prevalence of minimally invasive surgery (MIS) techniques for the treatment of adult spinal deformity. SUMMARY OF BACKGROUND DATA: There is a paucity of data available on the practice pattern, prevalence of minimally invasive spine surgery, and the preferred minimally invasive techniques in the treatment of adult spine deformity. METHODS: An electronic nine-question survey regarding individual usage pattern of minimally invasive spine surgery techniques was administered in 2016 to the members of the Scoliosis Research Society. Determinants included complexity in condition of patient population, prevalence of use of minimally invasive techniques in the surgeon's practice, prevalence of use of a particular MIS technique, strategy elected during surgery, adoption of staging of procedures and timing between staging of procedures. RESULTS: A total of 357 surgeons responded (61.3% response rate), and 154 (43.1%) of the respondents said that they use MIS as a part of their surgical treatment of adult spinal deformity. However, of these 154 respondents, 67 (43.5%) said that their MIS usage in deformity practice was between 1% and 20%. Only 11 (7.2%) said that they used MIS 81% to 100% of the time. The top MIS approaches that surgeons chose were MIS lateral lumbar interbody fusion 109 (70.59%) and MIS percutaneous screws 91 (58.8%). CONCLUSIONS: The low rate of adoption of these techniques among the SRS members may be due to the false perception that there is not enough data to support that MIS techniques are better. This and the fact that a practitioner needs to be facile at different MIS techniques may be the true impediment to the adoption of MIS techniques in the treatment of ASD. LEVEL OF EVIDENCE: Level IV.

Surgical Intervention for Cauda Equina Syndrome in the Second and Third Trimesters of Pregnancy: A Report of Three Cases.

CASE: Low back pain affects >50% of pregnant women. However, cauda equina syndrome (CES) during pregnancy is rare. Because a delay in treatment increases the risk of irreversible neurologic damage, acute onset is regarded as a surgical emergency. We describe 3 cases of CES in pregnant women at 24, 27, and 30 weeks' gestation, respectively. CONCLUSION: All 3 of the patients underwent surgical decompression in the prone position under general anesthesia with continuous external monitoring of the fetal heart rate. Intraoperative findings were noteworthy for epidural venous plexus engorgement in 2 of the patients. There were no complications for the patients or the fetuses, and all 3 of the patients had postoperative resolution of the neurologic symptoms.

Stand-alone Anterior Lumbar Interbody, Transforaminal Lumbar Interbody, and Anterior/Posterior Fusion: Analysis of Fusion Outcomes and Costs.

Fusion outcomes and costs of stand-alone anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF) in association with posterior fusion, and anterior/posterior (A/P) fusion were compared using clinical, radiographic, and billing data. Adult patients with symptomatic 1- or 2-level degenerative disk disease in isolation or in association with a grade 1 or 2 degenerative or lytic spondylolisthesis and canal and/or foraminal stenosis who underwent elective stand-alone ALIF, TLIF, or A/P fusion were compared. The analysis focused primarily on fusion rates and costs and secondarily on radiographic and clinical parameters. One hundred six patients at least 2 years beyond surgery (ALIF, 53; TLIF, 17; A/P fusion, 36) were reviewed. Demographics were similar except for age, with the ALIF group being younger (mean, 37.8 years) than the other groups (TLIF, 53.1 years; A/P fusion, 48.2 years). There were no differences between the groups in fusion rates or outcomes as assessed by the Numeric Rating Scale. Compared with the other 2 groups, the ALIF group had a significantly shorter operative time, less blood loss, and a shorter stay (P<.0001). Evaluation of radiographic parameters revealed significant differences regarding disk angle (P<.001), disk height (P<.0001), and pelvic tilt (P=.001) favoring ALIF and A/P fusion over TLIF. Stand-alone ALIF should be considered in the management of patients with 1- or 2-level lumbar degenerative disk disease for which the pathology can be addressed adequately via this approach. [Orthopedics. 2018; 41(5):e655-e662.].

Development of Bilateral Facet Cysts Causing Recurrent Symptoms After Decompression and the Placement of an Intralaminar Implant: A Case Report.

CASE: We report the development of bilateral symptomatic facet joint cysts in a 78-year-old man who had been treated with decompression and placement of a coflex device (Paradigm Spine) at L3-L4 and L4-L5. Preoperative imaging clearly demonstrated fluid in the facet joints without cysts. He underwent standard surgical treatment, but developed symptomatic facet joint cysts at 4 months postoperatively. The patient was treated with a revision decompression and replacement of the devices; there were no issues at the 32-month follow-up. CONCLUSION: While the coflex device has possible long-term biomechanical advantages, vigilance with adherence to appropriate decompression surgical technique is necessary.

One-step Minimally Invasive Pedicle Screw Instrumentation Using O-Arm and Stealth Navigation.

STUDY DESIGN: Description of a navigated, single-step, minimally invasive technique for the placement of pedicle screws. OBJECTIVE: To describe a new technique for minimally invasive placement of pedicle screws in the lumbar spine using O-arm and StealthStation navigation in combination. SUMMARY OF BACKGROUND DATA: Minimally invasive surgical techniques are described in the literature as safe and effective methods for pedicle screw instrumentation. These techniques increase radiation exposure and prompt multiple instrument passes through the pedicle. MATERIALS AND METHODS: In total, 35 adult patients (187 screws) underwent lumbar surgery with pedicle screw placement using the 1- (8 patients/48 screws) or 2-step (27 patients/139 screws) technique. Complications associated with instrumentation were noted. Pedicle screw position was evaluated. RESULTS: Of 187 screws placed, 181 (96.8%) were found to be fully contained within the pedicle (grade 1) and 4 (2.1%) had a breach of <2 mm. In the 1-step technique, no screws were malpositioned. One screw at S1 with inadequate fixation was replaced with a screw 1 mm larger in diameter. In the 2-step technique, 2 screws (1.06% overall) were revised due to inferior breach of the pedicle. No neurological sequelae were noted. Also, 1 screw was deemed too long at S1 and was replaced with a shorter screw. None of the revised pedicle screws caused neuromonitoring changes and the breaches were found intraoperatively on 3D imaging. CONCLUSIONS: Using O-arm and StealthStation navigation with minimally invasive surgical technology for placement of posterior spinal instrumentation is safe, effective, and limits radiation exposure.

Spinopelvic Parameters in Asymptomatic Subjects Without Spine Disease and Deformity: A Systematic Review With Meta-Analysis.

STUDY DESIGN: A systematic review with meta-analysis. OBJECTIVE: To combine published data, focusing on the development of optimal spinopelvic parameters in adult asymptomatic subjects without spine deformity while taking into consideration the impact of potential confounders. SUMMARY OF BACKGROUND DATA: A well-grounded approach to define the optimal spinopelvic parameters is necessary for planning surgical correction of spine deformity. MATERIALS: Selection criteria: (1) randomized and nonrandomized prospective, cross-sectional, and retrospective studies; (2) participants: asymptomatic subjects without spine deformity aged above 18 years; (3) studied parameters: lumbar lordosis (LL), pelvic incidence, sacral slope, and pelvic tilt; (4) potential confounders: method of measurement, sex, age, ethnicity, weight, height, and body mass index. Search method: Ovid MEDLINE (1946-current) and EMBASE (1980-current), all years through October 2015 were included. Data were collected: number of enrolled subjects, means of the studied characteristics, SD, SE of the means, 95% confidence intervals. A meta-analysis was performed to evaluate the pooled means and range of optimal values (pooled mean±pooled SD) taking into consideration the impact of confounders. The GRADE approach was applied to evaluate the level of evidence. RESULTS: Seventeen of 1018 studies were included (2926 subjects from 9 countries). The pooled means and the optimal ranges were: LL (L1-S1), 54.6 (42-67) degrees; LL (L1-L5), 37.0 (22-53) degrees; pelvic incidence, 50.6 (39-62) degrees; sacral slope, 37.7 (28-48) degrees; pelvic tilt, 12.6 (3-22) degrees. The pooled results were statistically significant (P<0.001), but heterogeneous. Impact of the following confounders was revealed: method of measurement, ethnicity, age, and body mass index. A methodology was created to define an individualized optimal value and range of each studied parameter taking into consideration the influence of confounders. CONCLUSIONS: The pooled results and developed methodology can be used as diagnostic criteria for evaluation of the spinopelvic parameters, planning of surgical interventions and evaluation of the treatment effect.

Strain in Posterior Instrumentation Resulted by Different Combinations of Posterior and Anterior Devices for Long Spine Fusion Constructs.

STUDY DESIGN: Clinically related experimental study. OBJECTIVE: Evaluation of strain in posterior low lumbar and spinopelvic instrumentation for multilevel fusion resulting from the impact of such mechanical factors as physiologic motion, different combinations of posterior and anterior instrumentation, and different techniques of interbody device implantation. SUMMARY OF BACKGROUND DATA: Currently different combinations of posterior and anterior instrumentation as well as surgical techniques are used for multilevel lumbar fusion. Their impact on risk of device failure has not been well studied. Strain is a well-known predictor of metal fatigue and breakage measurable in experimental conditions. METHODS: Twelve human lumbar spine cadaveric specimens were tested. Following surgical methods of lumbar pedicle screw fixation (L2-S1) with and without spinopelvic fixation by iliac bolt (SFIB) were experimentally modeled: posterior (PLF); transforaminal (TLIF); and a combination of posterior and anterior interbody instrumentation (ALIF+PLF) with and without anterior supplemental fixation by anterior plate or diverging screws through an integrated plate. Strain was defined at the S1 screws, L5-S1 segment of posterior rods, and iliac bolt connectors; measurement was performed during flexion, extension, and axial rotation in physiological range of motion and applied force. RESULTS: The highest strain was observed in the S1 screws and iliac bolt connectors specifically during rotation. The S1 screw strain was lower in ALIF+PLF during sagittal motion but not rotation. Supplemental anterior fixation in ALIF+PLF diminished the S1 strain during extension. Strain in the posterior rods was higher after TLIF and PLF and was increased by SFIB; this strain was lowest after ALIF+PLF, as supplemental anterior fixation diminished the strain during extension, in particular, cages with anterior screws more than anterior plate. Strain in the iliac bolt connectors was mainly determined by direction of motion. CONCLUSIONS: Different devices modify strain in low posterior instrumentation, which is higher after transforaminal and posterior techniques, specifically with spinopelvic fixation. LEVEL OF EVIDENCE: N/A.

An analysis of spine fusion outcomes in sheep pre-clinical models.

PURPOSE: The ovine model is often used to evaluate new spine fusion technologies prior to clinical testing. An important aspect of designing sheep surgery protocols is to select the appropriate postoperative time period for comparing fusion outcomes. Unfortunately, determining the ideal study endpoint is complicated by the fact that prior published studies have not used consistent timeframes. Thus, the primary aim of this study was to provide a reference for investigators as to the expected fusion outcomes of control groups at varying timepoints in sheep spine surgery models. METHODS: We identified published sheep fusion studies using autograft, interbody cages, and/or instrumentation. Fusion data were extracted, converted to a common scale, and analyzed across studied timepoints. RESULTS: Overall, 29 studies of 360 fusion levels were identified: 11 ALIF (158 levels), 3 PLIF/TLIF (28 levels), 8 PLF (90 levels), and 7 ACDF (84 levels). Studied timepoints ranged from 4 to 48 weeks postoperative. In general, fusion rates varied across techniques and instrumentation. The time to reach solid fusion differed by as many as 20 weeks between control groups. CONCLUSIONS: Recommended timeframes for future studies designed to show either superiority over controls or equivalent outcomes with controls were developed based on aggregate results. Designating ideal study endpoints for sheep fusion models has both ethical implications associated with responsible use of animals in research, and economic implications given the cost of animal research. The current results can guide the development of future research methods and help investigators choose appropriate study timelines for various control groups.

Sacroiliac Joint Treatment Personalized to Individual Patient Anatomy Using 3-Dimensional Navigation.

During the past 10 years, the sacroiliac (SI) joint has evolved from being barely recognized as a source of pain, to being a joint treated only nonsurgically or with great surgical morbidity, to currently being a joint treated with minimally invasive techniques that are personalized to the individual patient. The complex 3-dimensional anatomy of the SI joint and lack of parallel to traditional imaging planes requires a thorough understanding of the structures within and around the SI joint that may be at risk of injury. Thus, the SI joint is ideally suited for intraoperative 3-dimensional imaging and surgical navigation when being treated minimally invasively.

Patient-Specific Templating of Lumbar Total Disk Replacement to Restore Normal Anatomy and Function.

The purpose of this study was to develop a tool to determine optimal placement and size for total disk replacements (TDRs) to improve patient outcomes of pain and function. The authors developed a statistical shape model to determine the anatomical variables that influence the placement, function, and outcome of lumbar TDR. A patient-specific finite element analysis model has been developed that is now used prospectively to identify patients suitable for TDR and to create a surgical template to facilitate implant placement to optimize range of motion and clinical outcomes. Patient factors and surgical techniques that determine success regarding function and pain are discussed in this article.

What Is the Clinical Relevance of Radiographic Nonunion After Single-Level Lumbar Interbody Arthrodesis in Degenerative Disc Disease?: A Meta-Analysis of the YODA Project Database.

STUDY DESIGN: Meta-analysis of 4 randomized controlled clinical trials (RCTs). OBJECTIVE: The aim of the study was to determine if patients with degenerative disc disease who achieve radiographic fusion after single-level lumbar interbody arthrodesis have better clinical outcomes than patients with radiographic pseudarthrosis at 12 and 24 months postoperative. SUMMARY OF BACKGROUND DATA: The clinical relevance of successful fusion after lumbar arthrodesis with recombinant human bone morphogenetic protein-2 or iliac crest bone autograft has recently been questioned in the literature. METHODS: Individual patient-level data of 4 RCTs were obtained from the Yale University Open Data Access Project project and analyzed. Clinical outcomes (Oswestry Disability Index [ODI]; Numeric Rating Scales [NRSs] for back and leg pain) were compared between patients with radiographically confirmed fusion and those with radiographic nonunion 1 and 2 years postoperative. The results of each study were first analyzed separately, and then were pooled by meta-analysis. The GRADE approach was applied to evaluate the level of evidence. RESULTS: A total of 496 patients with clinical and radiographic data at 1- and 2-year follow-ups were identified. Of these, 5.5% (95% confidence interval: 3.7; 8.3) had radiographic nonunion which did not require reoperation. Patients with fusion had better improvements in ODI (P < 0.001) and NRS back pain scores (P < 0.001). The overall percentage of fused patients with ODI and NRS back pain scores that exceeded the criteria for minimal clinically important differences was also significantly higher than that of patients with nonunion (ODI, odds ratio [OR] = 2.7, P = 0.019; NRS back pain, OR = 3.5, P = 0.033). The predictive values of fusion for clinical outcomes, however, were poor, with low specificity and low negative predictive values. CONCLUSION: The presence of radiographic fusion is clinically significant, as patients with fusion had better clinical outcomes at 1 and 2 years postoperative than those with nonunion; however, patient-centered clinical outcomes should also be taken into consideration as independent, complimentary variables when assessing treatment success.

A new 3-dimensional method for measuring precision in surgical navigation and methods to optimize navigation accuracy.

PURPOSE: Description of a novel method for evaluation of pedicle screws in 3 dimensions utilizing O-arm(®) and StealthStation(®) navigation; identifying sources of error, and pearls for more precise screw placement. METHODS: O-arm and StealthStation navigation were utilized to place pedicle screws. Initial and final O-arm scans were performed, and the projected pedicle probe track, projected pedicle screw track, and final screw position were saved for evaluation. They were compared to evaluate the precision of the system as well as overall accuracy of final screw placement. RESULTS: Thoracolumbar deformity patients were analyzed, with 153 of 158 screws in adequate position. Only 5 screws were malpositioned, requiring replacement or removal. All 5 were breached laterally and no neurologic or other complications were noted in any of these patients. This resulted in 97 % accuracy using the navigation system, and no neurological injuries or deficits. The average distance of the screw tip and angle of separation for the predicted path versus the final pedicle screw position were analyzed for precision. The mean screw tip distance from the projected tip was 6.43 mm, with a standard deviation of 3.49 mm when utilizing a navigated probe alone and 5.92 mm with a standard deviation of 3.50 mm using a navigated probe and navigated screwdriver (p = 0.23). Mean angle differences were 4.02° and 3.09° respectively (p < 0.01), with standard deviations of 2.63° and 2.12°. CONCLUSIONS: This new technique evaluating precision of screw placement in 3 dimensions improves the ability to define screw placement. Pedicle screw position at final imaging showed the use of StealthStation navigation to be accurate and safe. As this is a preliminary evaluation, we have identified several factors affecting the precision of pedicle screw final position relative to that predicted with navigation.

Patient-Controlled Transdermal Fentanyl Versus Intravenous Morphine Pump After Spine Surgery.

Patient-controlled analgesia (PCA) is regularly used to manage pain following major surgery. The fentanyl hydrochloride iontophoretic transdermal system (ITS) was developed to overcome some of the limitations of intravenous (IV) PCA. The small, self-adhesive, needle-free disposable system is applied to the skin on the upper arm or chest and is controlled by patients clicking a button on the device. The authors identified patients who were underwent spinal surgery from 2 prior multicenter, randomized studies and analyzed their data. Of the 1296 patients in the original trials, 170 underwent spine surgery procedures: 90 were randomized to the fentanyl ITS (40 mcg/activation) and 80 to IV PCA morphine (1 mg/dose). More patients treated with the fentanyl ITS rated their method of pain control as "excellent" across all time points, but differences did not reach statistical significance. However, investigators' ratings of "excellent" satisfaction with study treatment were significantly higher for the fentanyl ITS. Discontinuation rates and overall adverse event rates were similar between groups. The only significant difference was that patients treated with the fentanyl ITS had a higher rate of application site reactions than infusion site reactions in the IV PCA morphine group; the reactions were typically mild-to-moderate erythema that resolved shortly after removal of the fentanyl ITS device and did not require further treatment. Ratings of satisfaction with pain control method were consistently higher for the fentanyl ITS than the IV PCA morphine. The 2 groups had a similar safety profile. These results suggest that the fentanyl ITS appears to be a safe, efficacious alternative to IV PCA in spine surgery patients.

Predictors of spine deformity progression in adolescent idiopathic scoliosis: A systematic review with meta-analysis.

AIM: To evaluate published data on the predictors of progressive adolescent idiopathic scoliosis (AIS) in order to evaluate their efficacy and level of evidence. SELECTION CRITERIA: (1) study design: randomized controlled clinical trials, prospective cohort studies and case series, retrospective comparative and none comparative studies; (2) participants: adolescents with AIS aged from 10 to 20 years; and (3) treatment: observation, bracing, and other. SEARCH METHOD: Ovid MEDLINE, Embase, the Cochrane Library, PubMed and patent data bases. All years through August 2014 were included. Data were collected that showed an association between the studied characteristics and the progression of AIS or the severity of the spine deformity. Odds ratio (OR), sensitivity, specificity, positive and negative predictive values were also collected. A meta-analysis was performed to evaluate the pooled OR and predictive values, if more than 1 study presented a result. The GRADE approach was applied to evaluate the level of evidence. RESULTS: The review included 25 studies. All studies showed statistically significant or borderline association between severity or progression of AIS with the following characteristics: (1) An increase of the Cobb angle or axial rotation during brace treatment; (2) decrease of the rib-vertebral angle at the apical level of the convex side during brace treatment; (3) initial Cobb angle severity (> 25(o)); (4) osteopenia; (5) patient age < 13 years at diagnosis; (6) premenarche status; (7) skeletal immaturity; (8) thoracic deformity; (9) brain stem vestibular dysfunction; and (10) multiple indices combining radiographic, demographic, and physiologic characteristics. Single nucleotide polymorphisms of the following genes: (1) calmodulin 1; (2) estrogen receptor 1; (3) tryptophan hydroxylase 1; (3) insulin-like growth factor 1; (5) neurotrophin 3; (6) interleukin-17 receptor C; (7) melatonin receptor 1B, and (8) ScoliScore test. Other predictors included: (1) impairment of melatonin signaling in osteoblasts and peripheral blood mononuclear cells (PBMC); (2) G-protein signaling dysfunction in PBMC; and (3) the level of platelet calmodulin. However, predictive values of all these findings were limited, and the levels of evidence were low. The pooled result of brace treatment outcomes demonstrated that around 27% of patents with AIS experienced exacerbation of the spine deformity during or after brace treatment, and 15% required surgical correction. However, the level of evidence is also low due to the limitations of the included studies. CONCLUSION: This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.