Pedicle Screw Malposition in Spine Arthrodesis Surgeries With O-ARM-guided Navigation

Occurrence of Pedicle Screw Malposition in Spine Arthrodesis Surgeries Performed With O-ARM-guided Navigation at a University Hospital: a Randomized Controlled Trial

Background: Throughout the history of spinal deformity there have been continuous advances in the surgical treatment. Although many techniques have been successfully developed despite the anatomy complex, screw placement still remains difficult with a significant risk of misplaced implants. The O-ARM guided Navigation is a scanner that allows imaging of screws intraoperatively and could be a tool to facilitate screw revision and reduce the occurrence of misplaced implants. Methods: This is a prospective and randomized clinical study that will be carried out at the University Hospital of the Federal University of Piaui, which provides exclusive assistance to patients of the Unified Health System (UHS), in northeastern Brazil.

Study design: This is a prospective and randomized clinical study. Local: The study will be carried out at the University Hospital of the Federal University of Piauí (UH-FUPI), which provides exclusive assistance to patients of the Unified Health System (UHS), in the municipality of Teresina (PI), in northeastern Brazil, in the surgical center sector, involving patients undergoing neurosurgical procedures. Data collection will begin after approval by the UH-FUPI research ethics committee. Population and sample: The study population will consist of patients hospitalized for spinal deformities in the wards of the University Hospital of the Federal University of Piauí (UH-FUPI).

Patients aged 18 years or older with surgical indication for spine arthrodesis will be included in the study and will be randomized for corrective neurological or orthopedic spine surgeries performed with O-Arm technology (Intervention Group) and without O-arm (Group control). The surgeries performed electively in the three segments of the spine will be included in this study. Patients who do not sign the informed consent form and those without adequate records in medical records that do not allow the analysis of the data provided for this research will be excluded. Sample size: The sample size of the present study was calculated with the aim of comparing the incidence of misplacement of screws between two approaches, the first using a navigator and the other without. Setting the power of the test at 80% and the confidence level at 95%, the incidence of misplacement of screws known in the literature with the use of a navigator is = 9.8% and without use = 15%. Thus, at least 496 screws would be needed in each arm of the study. Using data from the study by Jin, Liu, Qiu et al. (2017), we noticed that 1145 screws were inserted in 144 patients, generating an average of approximately 8 screws per patient. Thus, at least 62 patients would be needed in each arm. The calculations necessary to determine the sample size were performed by the formula where, is the order percentile of the standard normal distribution, is the order percentile of the standard normal distribution, is the proportion of screw misplacement without using the navigator, is proportion of screw misplacement using the navigator and is the midpoint of the proportions. Data collect: Data will be collected through medical records, which will be completed in the data collection form, after the procedure. The variables analyzed will be: type of surgery performed, technique used, which vertebrae underwent surgical intervention with the implantation of screws, number of screws in each vertebra, presence or not of invasion of the pedicle cortex after analysis with CT, in addition to the description of the affected vertebra , which screws invaded, measurement of invasion, in millimeters, and whether the position was medial or lateral. Statistical analysis: The collected data will be organized in tables and graphs. The program used to carry out the statistical tests will be SPSS Statistics. The method used to jointly analyze the relationship between the studied variables and the presence or absence of expected outcomes will be the Pearson chi-square test method. The admitted confidence interval is 95% and the p-value less than 0.05.

Ethical and legal aspects: All patients included will sign the informed consent form. Data collection will begin after approval of the study by the research ethics committee. All research ethics regulations will be followed according to the resolution of the National Health Council n° 466/12. Risks and benefits: The research risks involve the exposure of personal data and embarrassment to the participants. To work around such problems, patients will be identified by numbering, where only the researchers will have direct access to the patients' records, without photos or any record that could cause the dissemination of personal information. In addition, questions to participants will be asked with caution and empathy, in order to avoid any embarrassment to the patient. If it is demonstrated that the studied neurovagegation system significantly reduces the need for surgical repositioning of the pedicle screws, in addition to the benefit for the sample patient in the intervention group, who will not have to face yet another surgical approach, the FUPI may also be benefited, since the hospital will have, within its list, the option of a neuronavigation technology that brings real results to the hospital's patients.

Inclusion Criteria:

• spine deformities (spinal cord trauma, osteoarthritis, intervertebral disc degeneration, degenerative or isthmic spondylolisthesis, intervertebral disc degeneration, spinal stenosis and degenerative scoliosis).

Exclusion Criteria:

• anatomical abnormalities that can not be used the neuronavigation.