Objective. To identify predictors of indirect decompression of spinal nerve roots in patients with degenerative monosegmental central spinal canal stenosis in the lumbar spine after isolated direct lateral interbody fusion (XLIF). Material and Methods. This prospective study analyzes the treatment outcomes of 80 patients with multisegmental central degenerative spinal stenosis associated with instability of the spinal motion segment. All patients underwent single-level XLIF without additional posterior fixation. Based on early postoperative data, patients were divided into groups with no positive dynamics in neurological status (n = 58) and with positive dynamics in the form of a decrease in the lower extremity pain to 1 point on the VAS (n = 22). All patients underwent preoperative MRI, MSCT, lumbar spine radiography, and VAS questionnaire survey. Postoperatively, they underwent MRI and MSCT of the lumbar spine, and VAS questionnaire survey. The prognostic significance of the studied factors for treatment outcomes was determined using logistic regression analysis. Results. Factor analysis revealed significant prognostic factors for the effectiveness of indirect decompression of spinal nerve roots in the spinal canal after XLIF: lateral recess depth greater than 3.75 mm and body mass index greater than 35.97 kg/m2. According to a singlefactor model, it was revealed that the higher Hounsfield (HU) values in the bodies of adjacent vertebrae, a lower intervertebral disc, the presence of laterospondylolisthesis, intervertebral disc degeneration (Pfirrmann grades 4, 5), endplate changes of grades 4, 5, 6 according to Toshiba Endplate Scoring (TEPS) and the clinical picture of dynamic compression are moderate prognostic factors for successful indirect decompression of the nerve roots in the spinal canal after XLIF for degenerative central stenosis associated with instability of the spinal motion segment. Conclusion. Further studies are required to validate the identified prognostic criteria, as well as other possible prognostic indicators – the timing of bone block formation in the surgical area, the frequency of implant subsidence and its clinical significance in the long-term period, the long-term effect of indirect decompression, and the results of the ODI and SF-12 survey in the late postoperative period.
Objective. To establish the types of autonomic regulation in patients with adolescent idiopathic scoliosis based on the analysis of heart rate variability at the preoperative stage. Material and Methods. The study included 69 adolescents with idiopathic scoliosis, who underwent cardiointervalogram recording with subsequent spectral analysis at rest and during an active orthostatic test in order to assess the reserves of autonomic regulation. Very low frequency oscillations of the spectrogram, stress index of regulatory systems, and the total power of the spectrum were analyzed. Four types of autonomic regulation were determined: type I with moderate predominance of sympathetic and central regulation, type II with pronounced predominance of sympathetic and central regulation, type III with moderate predominance of parasympathetic regulation, and type IV with pronounced predominance of parasympathetic regulation. Results. At rest, a moderate predominance of sympathetic activity and central regulation with moderate stress of regulatory systems, or type I regulation was observed in 15 (22%) patients; a sharp increase in the activity of central regulation with the development of a state of vegetative dysfunction, or type II regulation – in two (3%) patients; a moderate predominance of parasympathetic activity, or type III regulation – in 39 (56%) examined patients; and a pronounced predominance of parasympathetic regulation with overstrain of the regulatory systems, or type IV regulation – in 13 (19%) patients. After the orthostatic test, most of the examined patients, 44 (64%), had type I regulation, while type II was registered in seven (10%) patients, type III – in 14 (20%), and type IV – in four (6%) patients. Conclusion. The background state of autonomic regulation of the heart rate in most adolescents with idiopathic scoliosis reflects the stability of adaptation mechanisms. Orthostatic testing allows identifying cases of instability of regulatory system associated with the risk of hemodynamic instability due to the moderate predominance of sympathetic autonomic regulation observed in most patients.
Objective. To analyze the causes of subsidence of modern support cages for vertebral body replacement in the early postoperative period after surgical treatment of thoracolumbar spine injuries. Material and Methods. A retrospective analysis of the data of 46 patients operated on in a single surgical session for unstable injuries of the thoracolumbar spine using a telescopic extendable vertebral body cage was performed. The degree of cage subsidence was assessed according to the criteria of Marchi et al.: penetration of the implant into the body of the adjacent cranial or caudal vertebral by 25% – grade 1,25–50% – grade 2, 50–70% – grade 3, 75–100% – grade 4. A comparative assessment of demographic, clinical, and radiographic parameters was performed in patients with and without cage subsidence within one year after surgery. Results. Implant subsidence was detected in 76.5% (n = 13) of patients intraoperatively and in 23.5% (n = 4) after 4 months during an outpatient appointment. Subsidence into the cranial body prevailed (76%, n = 13). The anterior/posterior sequence of surgery stages combined with osteopenia and osteoporosis dominated in the study group (83.3%, n = 10). Quantitative parameters such as age, segmental angle, ROI in HU, surface contact area index, as well as qualitative parameters such as female gender, period of injury, and its lowenergy nature had statistically significant differences between the study and control groups (p < 0,05). The augmentation of the screws and the length of fixation did not affect the formation of subsidence, but were associated with its magnitude. Conclusion. The use of modern expandable body replacement cages for reconstruction of the anterior spinal column leads to their subsidence in some cases. Patient age, female gender, reduced bone density, the area of the bone-implant contact, anterior/posterior stabilization, and the late period of injury significantly affect the formation of subsidence when using expandable vertebral body replacement cages. A mean implant-to-vertebral endplate contact area ratio of less than 0.4 is a promising predictor of subsidence which requires further study.
Objective. To evaluate the effectiveness of transpedicular reposition planning in patients with single-level injuries of the thoracic and lumbar vertebrae, depending on the target parameters. Material and Methods. The study included two representative groups, retrospective and prospective, each of 80 patients with thoracic and lumbar fractures with an average age of 39.2 ± 2.2 years. In the prospective group, morphometry of the spine was performed using CT data, to plan the restoration of the vertical dimensions of the vertebral body and closed decompression of the contents of the spinal canal using a transpedicular repositioning system within up to a month from the moment of injury. Based on the results of morphometry, the main target parameters were calculated, which were aimed at being achieved during the operation. Results. In the main group, the lumen deficit significantly decreased (from 39.5 ± 4.1% to 14.2 ± 3.1%) versus that in the control group (from 39.3 ± 4.6 to 22.1 ± 5.1%; p = 0.01), as well as the cross-sectional area of the spinal canal (from 37.4 ± 5.1% to 14.2 ± 3.1%) versus that in the control group (from 39.6±5.3% to 24.1 ± 5.5%; p = 0.01). The anterior vertebral body height was maximally restored, and the magnitude of bone fragment displacement into the spinal canal decreased (t < 0.05). A direct correlation was found between the size of the interbody spaces and the height of the vertebral body: between the anterior interbody space and the anterior height of the vertebral body in the main group – r = 0.485, in the control group – r = 0.594; and between the posterior interbody space and the posterior height of the vertebral body in the main group – r = 0.309, in the control group – r = 0.252. A strong correlation was obtained between the posterior height of the vertebral body and the spinal canal: r = 0.625 in the main group, r = 0.461 in the control group. The difference between the initial and calculated angle after surgery was 3.1° ± 0.5° in the main group and 5.6° ± 1.2° in the control group (p = 0.01). Conclusion. Preoperative planning which includes the use of calculated target parameters such as interbody spaces and segmental angles during surgery, allows for the maximum restoration of the vertical dimensions of the injured vertebral body and the performance of closed decompression of the spinal canal contents.
Objective. To perform a systematic analysis of contemporary scientific data characterizing the clinical effectiveness of expandable implants for vertebral body replacement in the complex surgical treatment of patients with thoracic and lumbar spine injuries. Material and Methods. The search for scientific sources was carried out in accordance with the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions and the PRISMA principles in the Cochrane Library, PubMed and Medline databases for the period 2015–2025 a total of 19 studies on the radiological and functional outcomes of the surgeries involving implantation of expandable spinal cages for thoracic and lumbar spine injuries were analyzed. Results. The technologies for spinal surgery have been developing rapidly over the recent decades. The improvements in minimally invasive techniques have required modifications to implants including those for anterior support spinal fusion. The implants of transformable geometry which allow the replacement of spinal defects that significantly exceed their original dimensions are of particular interest. The contemporary expandable spinal cages vary in the material they are made from and their transformation mechanisms. The literature describes successful cases of their use in thoracic and lumbar spine injuries. The authors demonstrate favorable surgical outcomes using combinations of screw-assisted fusion and interbody implants. Conclusion. Expandable spinal cages feature a wide range of applications in the treatment of spinal injuries. The advent of vertical lift mechanisms in intervertebral implants has led to a trend towards modifying surgical techniques, particularly the sequence of intervention stages. Despite differences in approaches, specialists favor minimally invasive implant placement, with radiographic and functional results showing no significant differences.
Objective. To evaluate the ability of the Index of Neurological and Degenerative Impairments (INDI) to reliably stratify patients with singlelevel cervical spinal stenosis depending on treatment tactics, through a retrospective analysis of clinical, neurological, and neuroimaging data. Material and Methods. A total of 176 patients with single-level cervical spinal stenosis treated in a neurosurgical hospital were screened. Of these, 77 patients were included in the study based on predefined criteria: Group 1 – conservative treatment (n = 22), Group 2 – surgical treatment (n = 41), and Group 3 – patients who received conservative treatment but were discharged without improvement and placed under observation (n = 14). Patients were treated strictly in accordance with the current Russian Clinical Guidelines for Degenerative Spinal Diseases. A statistical analysis of differences between the groups was performed using the INDI scale, and its prognostic significance was assessed. The INDI scale was used retrospectively, and the scale data did not influence treatment decisions. Results. Group 1 had an average INDI score of 2.58 ± 1.46, Group 2 – 6.30 ± 1.36, and Group 3 – 2.90 ± 0.36. Patients in Group 2 were younger (46.12 ± 10.65 vs. 53.90 ± 10.66 years in Group 1; p < 0.05), had more pronounced paresis (2.92 ± 0.46 vs. 1.63 ± 1.50; p < 0.05) and more severe degenerative changes (p = 0). Discriminant analysis confirmed significant differences between the groups (Wilks’ lambda = 0.279; p = 0), with INDI score and total neurological impairment score being the most discriminating factors (F = 92.78 and 92.47, respectively). The stratification accuracy was 93.5%. Conclusion. The INDI scale allows for a unified assessment of the severity of neurological disorders and degenerative changes of the spinal motion segment based on neuroimaging data. It demonstrated a good ability to differentiate between groups in a retrospective sample, however, further prospective studies are required to validate the method.
Objective. To determine the impact of isolated decompression of intracanal neurovascular structures of the spine on sagittal balance in patients with degenerative lumbar stenosis. Study registration number: NCT07139938, clinicaltrials.gov. Material and Methods. Adult patients with neurological and/or pain syndromes caused by degenerative lumbar stenosis confirmed by MRI will be enrolled in research centers across Russia. All patients will undergo isolated decompression of neurovascular structures without the use of any implants. The dynamics of sagittal balance parameters will be assessed at 3 and 12 months after surgery by comparing with preoperative data. The sample size was calculated in accordance with the hypothesis of non-inferiority. The study aims to enroll 165 patients. Patient recruitment will take 12 months, and the total duration of the study will be approximately 2 years. Anticipated results. This study will provide valuable information on the potential for spontaneous correction of sagittal spinal parameters following isolated decompression without the use of implants.
The results of surgical treatment of a 14-year-old female patient with a rare vertebrological disorder, multiple exostotic chondrodysplasia with spinal column involvement, are presented. Clinical, radiographic, MRI, histological and laboratory examinations were carried out. The observation revealed a massive space-occupying lesion in the spinal column with projected dimensions of 97 × 70 × 72 mm. The patient had narrowing of the intervertebral foramina with signs of compression of the L1–L2 and L2–L3 nerve roots on the left, secondary deformity and cranial displacement of the 12th rib on the left.
Objective. To analyze long-term radiological and clinical outcomes of treatment of neurologically intact burst fractures of the thoracolumbar junction and to determine the optimal method of surgical treatment. Material and Methods. A single-center retrospective cohort study was conducted. Inclusion criteria were: AOSpine type A3 or A4 fracture at the T11–L2 level; absence of spinal cord and its nerve root injury; patient availability for a follow-up examination 12 months or later after surgery. Surgical treatment methods were divided into six groups depending on surgical approach (posterior, anterior, or combined) and whether decompression was performed. Standard radiological parameters were evaluated at admission, immediately after surgery, and at the final examination. Clinical outcomes were assessed using the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI). Results. A total of 57 patients (50.9% female, 49.1% male; mean age 41.1 ± 14.6 years) were included in the study. The median follow-up period was 57.6 months [28.9–110.4]. The study groups were homogeneous in terms of sex, age, and most radiological parameters. The dynamics of radiological parameters did not differ significantly between the groups, with the exception of spinal canal stenosis (SS), which was significantly lower (p = 0.008) in the groups without decompression upon admission. Among patients who underwent stabilization procedures, a separate subgroup of patients with stenosis of more than 30% (n = 10, Me 34.8% [32.6–48.8]) on admission was identified. This subgroup showed the greatest reduction in stenosis over time, with a median decrease of –28.9% [–31.3; –13.6]. The overall incidence of Grade Ia complications according to Landriel-Ibañez classification was 26.3%. Grades IIb and IIIa were detected in four patients (7.0%), predominantly from groups with decompression (p = 0.025). Bony fusion was detected in the majority of patients (n = 50, 87.7%), including stable pseudarthrosis in four patients (7.0%) and unstable pseudarthrosis in three cases (5.3%). There were no significant differences in radiological outcomes between the groups (χ² test, p = 0.535), however, decompression was found to be a significant risk factor for pseudarthrosis (p = 0.039). Pseudarthrosis developed significantly more often in cases involving bilateral facet joint resection (p = 0.010). When assessing the clinical results, the pain severity at the surgical site did not differ significantly between the groups (p = 0.944). The lowest ODI scores were observed in the group of transpedicular fixation without decompression. Conclusion. Short-segment posterior pedicle screw fixation without laminectomy could be an effective treatment option for patients with neurologically intact burst fractures of the thoracolumbar junction with kyphotic deformity up to 21.5°, a decrease in the vertebral body anterior height down to 53.2%, and a vertebral body index over 0.53. In cases of spinal canal stenosis up to 49%, spontaneous bone fragment lysis with partial or complete canal remodeling can occur without decompressive surgery, provided rigid internal immobilization of the segment is achieved. Further prospective studies with a high level of evidence are necessary to determine the optimal surgical approach for treating neurologically intact thoracolumbar junction fractures.
Objective. To evaluate the effectiveness of a combination of transpedicular and transforaminal endoscopic approaches for the removal of lumbar spine herniations with a double compressive intracanal component: significant protrusion in the disc plane combined with an extremely high degree of rostral or caudal migration. Material and Methods. An analysis of two clinical cases and literature data on the use of a combination of transpedicular and transforaminal endoscopic approaches through a single skin incision was performed. The dynamics of pain syndrome according to the Visual Analog Scale (VAS), neurological status and MRI results were assessed. Results. In both cases, the migrated sequestrated fragments and significant disc plane protrusions were successfully removed, with complete regression of pain syndrome and restoration of function. No complications were reported. Conclusion. The presented combination of transpedicular and transforaminal endoscopic approaches is a promising and safe surgical method for treating patients with disc herniations, compressing neural structures both in the plane of the disc and in the area of the migrated fragment. Further studies on a larger sample are required.
Objective. To conduct a multifactorial assessment of the risks of intraoperative damage to the dura mater (DM) in patients who underwent primary and repeated interventions on the lumbar spine. Material and Methods. A retrospective comparative analysis of data from two groups of patients who underwent repeated (n = 144) and primary (n = 153) surgery for degenerative diseases of the lumbar spine was conducted. All surgeries were performed by two experienced surgeons using a standard posterior approach, intraoperative fluoroscopy, microsurgical techniques and binocular magnification. Intraoperative (presence of adhesions, damage to the dura mater, duration of surgery, blood loss, approach and stabilization) and clinical and anamnestic data (gender, age, body mass index, diagnosis, blood transfusion and revisions) were analyzed. Damage to the dura mater was assessed intraoperatively, during revision and based on MRI data. Statistical analysis was performed using the binary logistic regression model. Results. In repeated surgeries, epidural fibrosis was observed in 92.36% of patients, which significantly increased the risk of dura mater injury as compared to primary surgeries (15.2% vs. 1.9%; p < 0.001). According to multivariate analysis, the extent of surgical access does not have a statistically significant effect on dura mater injury. The presence of fibrosis increases the risk of injury by 4 times, while spine stabilization reduces it by 6 times. The effect of surgery duration on the risk of dura mater injury was not statistically proven. The main limitation of the study is the insufficient postoperative MRI screening, which may lead to the underestimation of the incidence of complications. Conclusion. Epidural fibrosis is a key risk factor for damage to the dura mater during revision surgery. Its prevention is a pressing issue in surgery for lumbar spine dorsopathies.
Objective. To perform a non-systematic review of classifications of screw malpositions in transpedicular fixation of thoracic and lumbar spine deformities and to develop a tactical classification of screw malpositions in instrumental fixation of scoliotic deformities of the spine with a consensus assessment (kappa coefficient). Material and Methods. A search of studies was conducted in the Pubmed, eLibrary, and Google databases that evaluated the location of screws using or justifying the classification. Given the narrow specificity of the topic, publications of any design were included in the sample. Based on the data obtained, the authors proposed a tactical classification of screw malpositions in instrumental fixation of scoliotic deformities of the spine with an assessment of expert agreement using the Cohen’s kappa coefficient. Results. A total of 139 articles were found in the databases, including 21 articles from references. Of them, 66 articles did not correspond to the topic of the study, 12 – did not have the open-text access, and 85 – had open-text access. Twenty articles met the inclusion criteria. The analysis showed that classifications used mainly determine the displacement of screws into the lumen of the spinal canal without taking into account clinical manifestations and treatment tactics. Five classifications have been proposed to assess the position of screws in scoliosis, while only one determines the tactics of patient management based on a score assessment. Conclusion. An objectified method for assessing the accuracy of screw position is needed to provide additional evidence of the safety of malpositions and to determine the clinical significance of malpositions, risk factors associated with incorrect installation, and further actions of the surgeon.
Objective. To compare the capabilities of the most common open and minimally invasive TLIF techniques in the correction of segmental lordosis in patients with degenerative diseases of the lumbar spine, based on a non-systematic literature review. Material and Methods. Study design: non-systematic structured literature review. Articles published for the last 5 years were searched using the following keywords: degenerative, lumbar open mis TLIF, segmental restoration, segmental lordosis, degenerative, spine, TLIF. Results. Seventeen sources that met the inclusion criteria were included in the study. Among the included original studies, a large variability in the corrective capabilities of open and minimal TLIF was revealed - the achieved values of segmental lordosis/amount of correction can differ by more than 4 times among authors. A number of reasons were identified influencing this but not mentioned in systematic reviews: lack of proper preoperative examination of patients and planning of intervention, ambiguous intraoperative technique for performing correction, different initial values of the segmental angle (kyphosis), and lack of standardized technique for measuring angular parameters. Conclusion. The corrective possibilities of open and minimally invasive TLIF still need to be clarified. The wide variation of segmental lordosis values in existing articles makes it difficult for an outside observer to correctly interpret the results and requires carefully designed meticulous studies.
Objective. To perform multicomponent assessment of the results of surgical treatment of patients with idiopathic scoliosis of less than 40° according to Cobb and their compliance with patients’ expectations. Material and Methods. A total of 105 patients (97 women and 8 men) with an average age of 18.8 years, including 51 (48.6%) patients aged 18 years and older, were operated on for idiopathic scoliosis with a primary curve that did not exceed 40° (average 34.9°) at the time of surgery. Surgery was performed using Drummond instrumentation (2 patients), Antares system (4), and CDI (99), including using pedicle screws in 47 cases. The average period of postoperative follow-up was 51.1 months (range 24 to 170 months). Examination methods included clinical and radiological examination, SRS-24 questionnaire, and examination by a clinical psychologist. Results. In the overall group of 105 patients, the primary curve decreased during the intervention from 34.9° to 11.6° (correction – 66.7%), and at the end of the observation period it was 14.1° (loss of correction – 10.7%). The countercurvature correction was 60.1% with a subsequent loss of correction of 1.1° (7.4% of the achieved correction). Transpedicular fixation resulted in significantly greater correction of the primary curve (24.7° vs. 21.7°) with a smaller loss of correction (0.7° vs. 5.4°). Survey using the SRS-24 questionnaire demonstrated significant positive trends in the overall score (the so-called Grand Total) and in the domains of general and professional activity. Negative trends were noted for the assessment domains of postoperative appearance and satisfaction with treatment results. Conclusion. Idiopathic scoliosis with a primary curve less than 40° is often treated surgically due to patient’s demand. A significant proportion of patients are not fully satisfied with the outcome. Indications for surgery for such deformities should be formulated strictly on an individual basis, and patients require special preparation, primarily psychological.
Objective. To evaluate the biomechanical properties of biodegradable poly-L-lactide cages on a cadaveric model of the cattle cervical spine. Material and Methods. Prototypes of interbody cervical implants were developed on the Ender 3v2 3D printer. The mechanical characteristics of experimental cage specimens were evaluated, and the orientation of the specimens during 3D-printing was investigated. Single-level cervical discectomy with fixation by a cage made of poly-L-lactide was performed in 12 cadaveric models. Biomechanical tests of the operated vertebral segment were carried out under cyclic loading conditions. Results. In this type of testing, the developed cervical cage models demonstrated high deformation stability under compression load, and the absence of deformation and migration in static and cyclic tests. Conclusion. The development of biocompatible biodegradable cervical cages is a promising direction in medicine. Given the high rate of postoperative complications associated with migration and subsidence of cages made of non-resorbable materials, biodegradable implants may become a competitive analog for cervical segment fixation.
Objective. To identify main negative factors influencing the comprehensive assessment of the results of surgical treatment of severe idiopathic scoliosis with a primary thoracic curve. Material and Methods. A total of 288 patients were operated on for idiopathic scoliosis with main thoracic curve (Lenke types 1, 2, 3 and 4) measuring 93.0° [85.0°; 105.0°] in 1999–2019. Out of them, 154 patients had the lumbar countercurvature of 62.0° [53.0°; 72.5°]. All patients were operated on using posterior segmental instrumentation with hook fixation, hybrid (hook fixation in the thoracic and transpedicular one in the lumbar and thoracolumbar spine) and transpedicular fixation. The median age of patients at the time of surgery was 15.0 [13.0; 17.0] years, and the median period of postoperative follow-up – 4.3 [3.0; 6.2] years. Clinical and radiological data in the preoperative, postoperative and in long-term postoperative periods, and data of the SRS-24 survey were analyzed. The threshold values of eight clinical parameters were evaluated based on their excess of reference parameters of the physiological norm and data substantiated by previously conducted studies. Results. The residual thoracic curvature of more than 70° was detected in 32 (11.1%) patients, thoracic kyphosis over 60° – in 22 (7.6%), shoulder girdle tilt more than 5 ° – in 39 (13.5%), correction less than 50% – in 108 (37.5%), clinical frontal imbalance – in 49 (17.0%), hypokyphosis – in 79 (27.4%), hypolordosis – in 37 (12.8%), and total SRS-24 score less than 80 points – in 7 (2.4%) patients. Excellent results were stated in 123 (42.7%) patients, good - in 118 (41%), including 42 (35.6%) with one or more significant negative factors; satisfactory results were stated in 44 (15.3%) patients, including 35 (79.5%) with critical negative factors. Unsatisfactory results were noted in 3 (1.0%) patients. Conclusion. Identification of statistically significant differences in 398 parameters made it possible to reveal eight negative factors that affect the outcome of treatment of severe thoracic scoliosis, and to determine their threshold values. Three critical negative factors have the greatest impact on the result of surgical treatment: the residual thoracic scoliotic curve more than 70°, thoracic hyperkyphosis more than 60° and shoulder girdle tilt more than 5°.
Objective. To determine the radiation doses of surgeons performing spinal stabilization operations using fluoroscopy and X-ray. Material and Methods. Design: prospective study and description of a case series. The sample included the most dose-related spine stabilization techniques: percutaneous transpedicular fixation (PTF, n = 11) and puncture kyphoplasty (PKP, n = 10). Effective radiation doses and equivalent radiation doses to the lenses of the eyes and the skin of the hands were evaluated. Results. In the PTF and PKP groups, the following values were obtained, respectively: effective radiation doses to the surgeon – 0.07 mSv and 0.09 mSv; equivalent radiation doses to the lens of the eye – 1.2 mSv and 2.45 mSv, and to the skin of the hands – 11.96 mSv and 5.59 mSv. Conclusion. The obtained values of effective radiation doses to the surgeon correspond to the recommended standards for radiation exposure to operating room personnel. The safe level of radiation will be exceeded after approximately 150 transpedicular fixation procedures or 82 PKPs, without taking into account other surgical interventions performed under radiographic guidance.
