Meta-analysis of efficacy of orthopedic robot-assisted versus freehand percutaneous sacroiliac screw fixation for posterior pelvic ring fractures / 中国组织工程研究

OBJECTIVE:Percutaneous sacroiliac screw internal fixation has become the main surgical procedure for the treatment of posterior pelvic ring fractures;however,the unassisted closure operation requires high operator experience and repeated fluoroscopy increases the radiation hazard for patients and medical personnel.This article compares the clinical efficacy of robot-assisted versus unassisted percutaneous sacroiliac screw placement for posterior pelvic ring fractures by meta-analysis. METHODS:Computer searches of CNKI,WanFang,VIP,CBM,PubMed,Embase,Cochrane Library and ClinicalTrials.gov were conducted from the time of database inception to December 2022.The literature on the clinical efficacy of robot-assisted versus freehand percutaneous sacroiliac screw placement in the treatment of posterior pelvic ring fractures was collected in and outside China.The data were independently screened and extracted by two investigators according to the inclusion and exclusion criteria,respectively.The quality of randomized controlled trials was evaluated using Cochrane risk assessment criteria.The quality of included cohort studies was assessed using the Newcastle-Ottawa Scale.Meta-analysis was performed using RevMan 5.4 software for inclusion metrics.Outcome metrics included operative time,intraoperative bleeding,fluoroscopy time,fluoroscopy frequency,number of holes drilled,Majeed postoperative function score,the excellent and good rates of Matta fracture reduction,the excellent and good rates of Gras screw position,fracture healing time and complications. RESULTS:(1)A total of 13 publications were included,2 were randomized controlled trials both referring to randomized methods,11 non-randomized controlled studies were evaluated for quality of literature according to the Newcastle-Ottawa Scale,1 scored 8,9 scored 7;and 1 scored 6;the quality of literature was good.A total of 748 patients were included,including 430 in the robot-assisted group and 318 in the freehand group.(2)The results of the meta-analysis showed that the operative time(MD=-28.30,95%CI:-40.20 to-16.40),intraoperative bleeding(MD=-6.36,95%CI:-10.06 to-2.66),intraoperative fluoroscopy time(MD=-12.13,95%CI:-19.54 to-4.72),intraoperative fluoroscopy frequency(MD=-17.39,95%CI:-29.00 to-5.78),number of intraoperative needle drillings(SMD=-9.50,95%CI:-14.27 to-4.73)and the excellent and good rates of Gras screw position(OR=8.65,95%Cl:3.26-22.92)in the robot-assisted group were significantly better than those in the freehand group(P<0.05).(3)In the robot-assisted group,the overall postoperative complication rate was significantly reduced(OR=0.10,95%Cl:0.02-0.48,P<0.05).(4)No significant difference was detected in fracture healing time(MD=-0.08,95%CI:-0.21,0.06),the excellent and good rates of Matta fracture repositioning rate(OR=2.06,95%Cl:0.97-4.39),and Majeed functional score(MD=0.91,95%CI:-0.31-2.13)between both groups(P>0.05). CONCLUSION:Compared with freehand sacroiliac joint nailing,robotic assistance shortens the operative time,reduces intraoperative bleeding,decreases radiation damage to patients and medical staff,improves the excellent and good rate of screw position,and reduces the overall incidence of postoperative complications in patients,but there was no significant improvement in fracture reduction quality,fracture healing time,and postoperative function.In the future,more large-sample,multicenter,and high-quality randomized controlled trials are still needed to verify.

Accuracy of sacroiliac screw placement in robot-assisted navigation / 中国组织工程研究

BACKGROUND:Orthopedic robots have been widely used in clinical practice,and relevant reports have shown that they have many advantages such as minimal trauma and short surgical time.However,there is currently no clear report on how accurate they are. OBJECTIVE:To evaluate the accuracy of robot-assisted sacroiliac screw insertion. METHODS:A total of 131 patients with sacroiliac joint fracture and dislocation and sacral fracture admitted to the Department of Trauma Surgery,Gansu Provincial Hospital from January 2020 to April 2023 were retrospectively collected,including 131 S1 screws and 46 S2 screws,totaling 177 screws.They were divided into two groups based on whether robot-assisted navigation was performed.There were 63 cases of sacroiliac screws inserted under robot-assisted navigation(observation group),with 36 males and 27 females,aged 19-72 years,with a mean age of(45.3±17.6)years.Among them,39 cases were fixed with only S1 screws,while 24 cases were fixed with S1S2 screws,resulting in a total of 87 sacroiliac screws.Under C-arm fluoroscopy,68 cases of sacroiliac screws were inserted with bare hands(control group),including 41 males and 27 females,aged 23-67 years,with a mean age of(42.6±21.3)years.Among them,46 cases were fixed with simple S1 screws,while 22 cases were fixed with S1S2 screws,resulting in a total of 90 sacroiliac screws.A postoperative CT scan was performed to evaluate the number of S1 screws,S2 screws,total screw level,and calculate accuracy based on the method introduced by SMITH et al. RESULTS AND CONCLUSION:(1)In the observation group,62 S1 screws were accurately placed(62/63),with an accuracy rate of 98%.24 S2 screws were accurately placed(24/24),with an accuracy rate of 100%.The total number of screws accurately placed was 86(86/87),with an accuracy rate of 99%.(2)In the control group,58 S1 screws were accurately inserted(58/68),with an accuracy rate of 85%.19 S2 screws were accurately inserted(19/22),with an accuracy rate of 86%.The total number of screws accurately inserted was 77(77/90),with an accuracy rate of 86%.(3)There was a statistically significant difference in the accuracy of the S1 screw,S2 screw,and total screw between the two groups(P<0.05).It is suggested that the placement of sacroiliac screws under robot navigation has higher accuracy compared to manual placement under C-arm fluoroscopy,but still has a lower error rate in placement.

Grey-scale Reversed T1-weighted MRI for Detecting Structural Lesions of the Sacroiliac Joint in Patients with Axial Spondyloarthritis / 中山大学学报(医学科学版)

ObjectiveTo analyze the value of grey-scale reversed T1-weighted （rT1） MRI in the detection of structural lesions of the sacroiliac joint （SIJ） in patients with axial spondyloarthritis （ax-SpA）. MethodsFifty-two ax-SpA patients who underwent both MRI and CT in our hospital within a week from February 2020 to December 2022 were retrospectively included. Both sacral and iliac side of each SIJ on oblique coronal images were divided into anterior， middle and posterior portion. Two radiologists reviewed independently three groups of MRI including T1-weighted imaging （T1WI）， rT1 and T1WI + rT1 images to evaluate the structural lesions like erosions， sclerosis and joint space changes in each of the 6 regions of the SIJ. One of the radiologist did the evaluation again one month later. CT images were scored for lesions by a third radiologist and served as the reference standard. Intra-class correlation coefficients （ICC） were calculated to test the inter- and intra-reader agreement for the assessment of SIJ lesions. A Friedman test was performed to compare the lesion results of MRI and CT image findings. We examined the diagnostic performance ［accuracy， sensitivity （SE） and specificity］ of different groups of MRI in the detection of lesions by using diagnostic test. A McNemar test was used to compare the differences of three groups of MRI findings. ResultsCT showed erosions in 71 joints， sclerosis in 65 and joint space changes in 53. Good inter-and intra-reader agreements were found in three groups of MRI images for the assessment of lesions， with the best agreement in T1WI + rT1. There were no difference between T1WI + rT1 and CT for the assessment of all lesions， nor between rT1 and CT for the assessment of erosions and joint space changes （P>0.05）. T1WI + rT1 yielded better accuracy and SE than T1WI in detection of all lesions （Accuracy erosions： 90.3% vs 76. 9%； SE erosions： 91.6% vs 76.1%； Accuracy sclerosis： 89.4% vs 80.8%； SE sclerosis： 84.6% vs 73.9%； Accuracy joint space changes： 86.5% vs 73.1%； SE joint space changes： 84.9% vs 60.4%； P<0.05）. rT1 yielded better accuracy and SE than T1WI in detection of erosions and joint space changes （Accuracy erosions： 87.5% vs 76.9%； SE erosions： 88.7% vs 76.1%； Accuracy joint space changes： 85.6% vs 73.1%； SE joint space changes： 83.0% vs 60.4%； P<0.05）. ConclusionsIn the detection of SIJ structural lesions in ax-SpA， rT1 improves the diagnostic performance and T1WI + rT1 is more superior to others.

Advances in the internal fixation surgical approach for sacroiliac joint dislocation caused by posterior pelvic ring injury / 局解手术学杂志

Injury of the posterior pelvic ring can easily be caused by high-energy impact,and sacroiliac joint dislocation is the most common.The sacroiliac joint,as the hub of load transfer between the trunk and lower extremities,is essential to maintain the stability of the posterior pelvic ring,and once dislocation occurs,restoring the stability of the posterior pelvic ring by timely surgery is necessary.The current surgical approaches for the internal fixation of sacroiliac joint are mainly divided into anterior approach and posterior approach.The choice of the surgical approach directly affects the exposure of the surgical field,the stability of internal fixation and the prognosis of patients;therefore,it is particularly important to select the appropriate surgical approach and fixation method.In this paper,we briefly review the selection of sacroiliac joint fixation points,surgical approaches and postoperative complications.

Longitud muscular, dolor y funcionalidad en adultos jóvenes con disfunción de la articulación sacroilíaca

Introducción: La disfunción de la articulación sacroilíaca es un trastorno patomecánico, en la cual se pierde la estabilidad y se altera el funcionamiento de la cintura pélvica; también se modifica la capacidad de trasmitir y disipar fuerzas desde los miembros inferiores hacia la columna y viceversa. El acortamiento de músculos como el dorsal ancho, isquiotibiales y espinales lumbares puede alterar el control motor y generar lumbalgia. Objetivo: Evaluar la longitud muscular del dorsal ancho, los isquiotibiales, los espinales lumbares, el dolor y la funcionalidad en adultos jóvenes a partir de la comparación de tres grupos de estudio: dolor lumbar, disfunción de la articulación sacroilíaca y control. Métodos: Se realizó un estudio de corte transversal. Se incluyeron 114 personas de ambos sexos. La longitud muscular se evaluó a través de pruebas específicas para cada músculo. La escala visual análoga y el Oswestry se utilizaron para medir el dolor y la funcionalidad, respectivamente. Las diferencias de las variables entre los grupos de estudio se calcularon con la prueba de Chi2. Resultados: No se observaron diferencias en cuanto a longitud muscular en los grupos de estudio. El grupo con disfunción de la articulación sacroilíaca presentó más personas con dolor y limitación funcional moderada-severa. Conclusiones: Las retracciones del dorsal ancho, los isquiotibiales y los espinales lumbares no se relacionaron con el dolor lumbar o la disfunción de la articulación sacroilíaca; sin embargo, los adultos jóvenes de este grupo presentaron más molestias y discapacidad.

Introduction: Sacroiliac joint dysfunction is a pathomechanical alteration, in which stability is lost and the functioning of the pelvic girdle is altered; the ability to transmit and dissipate forces from the lower limbs to the spine and vice versa is also modified. The shortening of muscles such as the latissimus dorsi, hamstrings and lumbar spinal muscles can alter motor control and generate low back pain. Objective: To evaluate the muscle length of latissimus dorsi, hamstrings and lumbar spinal muscles, pain and functionality in young adults by comparing three study groups: pain, sacroiliac joint dysfunction and control. Methods: A cross-sectional study was carried out. A total of 114 subjects of both sexes were included. Muscle length was assessed through muscle-specific tests. The Visual Analog Scale and the Oswestry were used to measure pain and functionality, respectively. Differences in variables between study groups were calculated with the Chi2 test. Results: No differences in muscle length were observed in the study groups. The group with sacroiliac joint dysfunction presented more individuals with pain and moderate-severe functional limitation. Conclusions: Latissimus dorsi, hamstring and lumbar spinal retractions were not related to low back pain or sacroiliac joint dysfunction; however, young adults in this group presented more discomfort and disability.

Sacroiliac joint dysfunction and lumbar pain. Evaluation in a Brazilian population / Disfunción de la articulación sacroilíaca y dolor lumbar. Evaluación en una población brasileña

Abstract: The study intended to evaluate the incidence and evolution of sacroiliac joint dysfunction (SIJD). To reach 50 patients with SIJD diagnosis, 192 patients with low back pain and failure in conservative approach were consecutively examined (26% incidence). Initially patients underwent intra-articular (IA) corticosteroid sacroiliac joint (SIJ) block followed, if necessary, by cooled SIJ radiofrequency or referred to surgical intervention, in order of complexity. From the 50 patients submitted to IA SI block, 41 (82%) referred pain and quality of life improvement and lesser rescue analgesics consumption for 25 weeks. The block induced a prompt onset of pain relief and there was a drop in mean pain score from 8 to 2 cm (p < 0.001) maintained up to 25 weeks. Rescue analgesic consumption also significantly dropped (p < 0.05). However, nine patients (18%) did not refer long lasting improvement in the third week evaluation and underwent cooled radiofrequency. From this population of nine, seven were successful (78%) while two were recommended surgery. In view of the 50 patients, 82% were comfortable after IA block, 18% were submitted to radiofrequency, with a success rate of 78%. The final incidence of surgery suggestion was 4%.

Resumen: El estudio pretende evaluar la incidencia y evolución de la disfunción de la articulación sacroilíaca (DASI). Para llegar a 50 pacientes con diagnóstico de DASI, se examinaron consecutivamente 192 pacientes con dolor lumbar y fracaso en el abordaje conservador (26% de incidencia). Inicialmente, los pacientes se sometieron a un bloqueo de la articulación sacroilíaca (ASI) con corticosteroides intraarticulares (IA) seguido, si era necesario, de radiofrecuencia ASI enfriada o remitidos a una intervención quirúrgica, en orden de complejidad. De los 50 pacientes sometidos al bloqueo IA SI, 41 (82%) refirieron mejoría del dolor y de la calidad de vida y menor consumo de analgésicos de rescate durante 25 semanas. El bloqueo indujo un rápido inicio del alivio del dolor y hubo una caída en la puntuación media del dolor de 8 a 2 cm (p < 0.001) mantenida hasta 25 semanas. El consumo de analgésicos de rescate también disminuyó significativamente (p < 0.05). Sin embargo, nueve pacientes (18%) no refirieron una mejoría duradera en la evaluación de la tercera semana y se sometieron a radiofrecuencia fría. De esta población de nueve, siete tuvieron éxito (78%), mientras que a dos se les recomendó cirugía. De los 50 pacientes, 82% se sintió cómodo después del bloqueo IA, 18% fue sometido a radiofrecuencia, con una tasa de éxito de 78%. La incidencia final de sugerencia de cirugía fue de 4%.

Surgical methods and treatment effects of the adult anterior dislocation of the sacroiliac joint / 中华骨科杂志

Objective:To explore the surgical methods and treatment effects of adult anterior dislocation of the sacroiliac joint (AADSJ).Methods:A multi-center retrospective case series study was conducted to analyze the clinical data of 25 cases admitted in 5 clinical centers (affiliations of authors in this article) from January 2016 to January 2021. There were 18 males and 7 females, aged 38.8±15.5 years (range, 18-83 years). The AADSJ clinical classification system was formulated based on the radiographic morphology of anterior dislocation of the sacroiliac joint, which includes two types. Type I: complete anterior dislocation of the sacroiliac joint, and displacement of the entire iliac auricular surface to the front of the sacrum. Type II: fracture of the sacroiliac joint combined with anterior dislocation, subdivided into 3 subtypes. Type IIa: iliac fracture involves the anterior 1/3 of the sacroiliac joint, and dislocation of the ilium anterior to the sacrum. Type IIb: iliac fracture involves the posterior 2/3 of the sacroiliac joint, and dislocation of the ilium anterior to the sacrum. Type IIc: iliac fracture involves the posterior 2/3 of the sacroiliac joint, and dislocation of the ilium anteromedial to the sacrum. The reliability and repeatability of the clinical classification, Tile classification and Young-Burgess classification were performed based on the results of two-phase assessments in four observers. The operations were performed by the lateral-rectus approach and the ilioinguinal approach. The operation time and intraoperative bleeding were recorded. Pelvic X-ray and CT scan were rechecked after the operation. The quality of fracture reduction was evaluated according to Matta score. The postoperative functional rehabilitation was evaluated according to the Majeed rehabilitation standard at one-year follow-up.Results:Among 25 cases in this study, there were 3 cases of Type I, 5 cases of Type IIa, 9 cases of Type IIb and 8 cases of Type IIc according to the clinical classification system. The Kappa values of reliability tests for the clinical classification, Tile classification and Young-Burgess classification were 0.681, 0.328 and 0.383, respectively. The Kappa values of repeatability tests for the clinical classification, Tile classification and Young-Burgess classification were 0.690, 0.221 and 0.395, respectively. The reliability and repeatability of the AADSJ clinical classification were significantly better than other classifications. There were 14 cases underwent lateral rectus abdominis approach and 11 cases underwent ilioinguinal approach. The operative time for managing anterior dislocation of the sacroiliac joint was 122.0±50.7 min (range, 65-148 min) through the lateral rectus abdominis approach, and through the ilioinguinal approach was 178.0±49.9 min (range, 110-270 min), with a significant difference ( t=2.76, P=0.011). The amount of intraoperative blood loss through the lateral rectus approach was 680±330 ml (range, 350-2,120 ml), which was significantly less than that through the ilioinguinal approach (1,660±968 ml, 680-3,300 ml), with a significant difference ( t=3.55, P=0.002). The follow-up period was 1-3 years. At one week after surgery, the quality of fracture reduction evaluated by Matta score showed that the excellent and good reduction rate of the lateral-rectus approach was 79% (11/14), and that of the ilioinguinal approach was 73% (11/14), with no statistically significant difference ( P=1.000). At a one-year follow-up, according to Majeed's criteria, the overall excellent and good rate of the lateral-rectus approach was 64% (9/14), which is similar to 64% (7/11) of that of the ilioinguinal approach. No fracture reduction loss or internal fixation loosening failure occurred. Conclusion:The AADSJ clinical classification system can accurately describe the imaging features and clinical manifestations of AADSJ, with high reliability and repeatability. The AADSJ can be treated by the lateral-rectus approach or the ilioinguinal approach, with similar therapeutic effects but the former having less trauma.

Treatment of iliac fracture combined anterior dislocation of the sacroiliac joint by the "ladder reduction method" / 中华骨科杂志

Objective:To investigate the clinical effect of "ladder reduction method" in the treatment of iliac fracture combined anterior dislocation of sacroiliac joint.Methods:The retrospective analysis was performed on 10 cases of iliac fracture combined anterior sacroiliac joint dislocation admitted to the Affiliated Hospital of Yunnan University from February 2010 to January 2022, among which 5 cases were males and 5 cases were females, aged ranging from 22 to 52 years, with an average age of 38.8 years. All patients were injured in car accidents including 5 cases of C1.2, 3 cases of C2, and 2 cases of C3 fractures according to Tile classification. All patients were treated with the "ladder reduction method" with plate and screw fixation. In the first step, 1-2 Schanz pins were inserted into the iliac crest to control the ilium, and the Schanz pins were appropriately pulled laterally; in the second step, the periosteal stripper was used to pry the reduction between the sacrum and ilium; in the third step, for the patients who still could not be reduced, a 2.5 mm diameter Kirschner wire was placed on the sacrum close to the iliac crest, and a periosteal stripper was inserted between the sacrum and iliac crest, with its tip against the Kirkner wire, and the iliac crest as the fulcrum for pry pulling to separate the two. In the fourth step, the pry was maintained, and then another 2.5 mm diameter Kirschner wire was placed on the sacrum close to the internal margin of the iliac bone. The periosteal stripper was continued to pry between the sacrum and the iliac bone, and the operation was repeated. At the same time, the anterior dislocation of the sacroiliac joint was reduced with traction of the lower limb. Postoperatively, the quality of reduction was evaluated by the Matta score, and the degree of functional recovery after pelvic fracture was evaluated by the Majeed score.Results:Four patients completed the reduction through the first and second steps, and 6 cases of refractory sacroiliac joint anterior dislocation were successfully reduced through the first to fourth steps. The fracture reduction time of 6 patients with refractory anterior sacroiliac joint dislocation was 39.67±3.09 min (range, 35-44 min), with intraoperative blood loss of 300.00±141.42 ml (range, 150-600 ml); in the other 4 cases, the fracture reduction time was 36.75±4.38 min (range, 30-42 min), and the intraoperative blood loss was 225.00±44.30 ml (range, 200-300 ml). All 10 patients were followed up for 12.9±3.7 months (range, 9-20 months). The anterior and posterior pelvic ring fractures were healed in all patients, and the fracture healing time was 12.77±1.62 weeks (range, 10.71-15.28 weeks). At the last follow-up, Matta evaluation was excellent in 5 cases, good in 1 case, and excellent in the other 4 cases. The Majeed scores of 6 cases were 86.50±6.08 points (range, 74-92 points), of which 5 cases were excellent and 1 case was good. The other 4 cases were 81.5±9.39 scores (range, 71-94), of which 2 were excellent and 2 were good.Conclusion:The "ladder reduction method" is a safe, effective and easy-to-operate method for the treatment of iliac fracture combined anterior dislocation of the sacroiliac joint, especially for refractory anterior dislocation of the sacroiliac joint, which can still obtain satisfactory curative effects.

Classification system of sacroiliac joint dislocation with ipsilateral sacral wing fracture and its validity examination and clinical application evaluation / 中华创伤杂志

Objective:To establish the classification system of sacroiliac joint dislocation with ipsilateral sacral wing fracture (SJDISWF), examine its reliability and evaluate the clinical application.Methods:A multi-center retrospective case series study was conducted to analyze the clinical data of 20 SJDISWF patients admitted to Third Affiliated Hospital of Southern Medical University, Honghui Hospital Affiliated to Xi′an Jiaotong University and Third Hospital of Hebei Medical University from January 2016 to December 2019. There were 8 males and 12 females, aged from 13-58 years［(34.7±13.2)years］. Based on the direction of sacral displacement, SJDISWF was divided into 3 types. Type I: the sacroiliac joint dislocated and the ipsilateral sacral wing fracture fragment was anteriorly prolapsed; Type II: the sacroiliac joint dislocated, the ipsilateral sacral wing fracture fragment was compressed or crushed, the anterior sacral foramen may fractured; Type III: the sacroiliac joint dislocated and the ipsilateral sacral wing fracture end was inserted into the sacral canal, causing an intra-sacral canal occupation. The reliability of the classification was performed based on the assessment results of two phases in four observers at 4-week intervals. Treatments were utilized based on the types I, II, III fractures, including anterior approach for open reduction and internal fixation, closed reduction and internal fixation or posterior approach for open reduction and internal fixation respectively. Postoperative fracture healing time was recorded. Quality of fracture reduction was graded according to Matta′s criteria. Majeed functional score was recorded at postoperative 3 months, 6 months and the final follow-up. Complications were detected as well.Results:The overall Kappa value of inter-observer reliability was 0.890. The overall Kappa value of intra-observer reliability was 0.854. There were 12 patients with type I, 7 with type II and 1 with type III. All patients went through the procedure uneventfully and were followed up for 6-36 months［(20.0±8.7)months］. All patients achieved clinical healing in 8-14 weeks［(10.2±1.7)weeks］. According to the Matta′s criteria for fracture reduction, the outcome was excellent or good in 83% (10/12) for type I, 71% (5/7) for type II and 0% (0/1) for type III, with the overall excellent rate of 75%. Majeed functional score was (74.6±5.2)points at postoperative 3 months and (84.4±5.8)points at postoperative 6 months ( P<0.01). According to Majeed functional score, the outcome was excellent or good in 75% (9/12) for type I, 100% (7/7) for type II and 0% (0/1) for type III at the final follow-up, with the overall excellent rate of 80%. There were no complications such as lateral femoral cutaneous nerve or sciatic nerve injury, lower extremity deep vein thrombosis, sacroiliac joint pain, failure of internal fixation or loss of fracture reduction during the follow-up. Conclusions:The SJDISWF classification has high reliability. The classification-oriented treatment strategy has achieved a relatively satisfactory restoration and functional recovery, indicating that the classification plays a certain role in guiding treatment selection for SJDISWF.

Clinical application of local anesthesia for TiRobot-assisted removal of sacroiliac screws / 中华创伤骨科杂志

Objective:To explore the feasibility and advantages and disadvantages of local anesthesia for TiRobot-assisted removal of sacroiliac screws by comparison with general anesthesia for TiRobot-assisted removal of sacroiliac screws.Methods:A retrospective study was performed in 39 patients with posterior pelvic ring fracture-dislocation who had undergone removal of percutaneous sacroiliac screws after fracture union from January 2017 to December 2020 at Department of Orthopaedic Surgery, Hospital Affiliated to Chengdu University. Their sacroiliac screws were removed with TiRobot assistance under local anesthesia (LA group) or general anesthesia (GA group). In the LA group of 18 cases, there were 10 males and 8 females, aged (43.3 ± 8.4) years (from 25 to 58 years); in the GA group of 21 cases, there were 12 males and 9 females, aged (44.9 ± 9.0) years (from 23 to 60 years). The 2 groups were compared in terms of time for planning screw removal path, fluoroscopy frequency, fluoroscopy time, operation time, anesthesia time, anesthesia cost, postoperative visual analogue scale (VAS) and postoperative ambulation time.Results:There was no statistically significant difference in baseline data between the 2 groups, showing comparability ( P>0.05). Follow-ups revealed grade A wound healing in all patients. There were no significant differences between the 2 groups in time for planning screw removal path, fluoroscopy frequency, fluoroscopy time or operation time ( P>0.05). The anesthesia time [(41.6 ± 8.3) min], anesthesia cost [(653.5 ± 102.6) yuan] and postoperative ambulation time [(2.6 ± 0.6) h] in the LA group were significantly less than those in the GA group [(52.3 ± 9.5) min, (2,475.6 ± 261.8) yuan and (8.7 ± 2.4) h] while the VAS score in the former group (3.8 ± 1.5) was significantly higher than that in the latter group (2.5 ± 1.3) (all P<0.05). Conclusions:It is feasible to use local anesthesia for TiRobot-assisted removal of sacroiliac screws. In TiRobot-assisted removal of sacroiliac screws, compared with general anesthesia, local anesthesia may lead to shorter anesthesia time, lower anesthesia cast and shorter ambulation time, but the patients need to be compliant enough.

Dynamic changes of pelvic incidence after pelvic fixation with second sacral alar-iliac in patients with degenerative scoliosis / 中华骨科杂志

Objective:To investigate how pelvic incidence (PI) would change during the follow-up in degenerative scoliosis (DS) patients who underwent second sacralalar-iliac (S 2AI) fixation and identify the possible factors associated with the changes in PI. Methods:The DS patients who underwent long fusion to pelvis with S 2AI fixation with a minimum follow-up of two years between November 2014 to January 2017 were retrospectively reviewed in this study. The following sagittal radiographic parameters were measured, including pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), PI minus LL (PI-LL), and sagittal vertical axis (SVA) at pre-operation, post-operation and 2-year follow-up. Patients were divided into two groups at immediate post-operation: PI decreased less than 5° or increased (Group PI stabilization); PI decreased larger than 5° (Group PI activity). Descriptive statistics were calculated for all patients in the form of mean value and standard deviation (SD). Comparisons of means between variables were performed using an unpaired Student's t test. Pearson correlation coefficienttest was performed to determine the correlations between all radiographic variables. Inter- and intra-observer reliability was assessed using intraclass correlation coefficient (ICC). The internal consistency of the measurements was characterized as excellent ( ICC≥0.9), good (0.7≤ ICC<0.9), acceptable (0.6< ICC≤0.7), poor (0.5≤ ICC<0.6), or unpredictable ( ICC<0.5). Results:There were no significant differences in terms of age, sex, radiographic measurements and scores of SRS-22 between twogroups preoperatively ( P>0.05). 80 DS patients with a mean age of 55.3±16.2 years were enrolled in this study with a mean follow-up period of 34.6±8.7 months. At post-operation, 39 patients (38.8%) were in group PI stabilization whose PI decreased from 45.7°±11.4° to 45.3°±11.2° with no significant difference; while the other 41 (61.2%) were in group PI activity whose PI significantly decreased from 51.6°±14.5° to 40.9°±14.0°. At the last follow-up, 24 patients (49%) in group PI activity had PI returned with an increase of larger than 5°; while the other 25 (51%) showed no increase with a mean ΔPI change of -4.2°. Subgroup comparison revealed that ΔPI, post-operation PI, post-operation PT and age were significantly different between the two subgroups. Pre-operation PI, post-operation PI, post-operation PT, post-operation PI-LL were significantly correlated with ΔPI at the last follow-up. Logistic regression analysis showed that post-operation PI was the associated factor ( OR=0.87, P=0.024). Conclusion:PI decreased in more than half of DS patients after spinal surgery using S 2AI screws, while returned among 48% of them during 2-year follow-up. Lower pre-operation PI, post-operation PI and PT were strongly associated with the return of PI.

Subluxación sacroilíaca en un equino criollo colombiano / Sacroiliac subluxation in a horse in Colombia

Resumen La subluxación sacroilíaca es una enfermedad claudiocógena de los miembros posteriores que se puede presentar de forma aguda o crónica. La causa de esta patología se debe principalmente a resbalones, tropezones o caídas de los miembros posteriores, el diagnóstico es difícil de realizar debido a la profunda ubicación anatómica de la articulación, métodos como la ecografía y pruebas de estrés entre otros, son los procedimientos más usados en el diagnóstico de la subluxación sacroiliaca. Por tratarse de una alteración que fácilmente puede confundirse con otras condiciones patológicas de la columna, la pelvis y/o de los miembros posteriores, el diagnóstico muchas veces se realiza por eliminación de otras causas de cojera. Los tratamientos convencionales aún se proponen en la literatura, sin embargo, cada vez como opción para el tratamiento de esta patología. El presente reporte describe el caso de un equino criollo que padeció una subluxación sacroiliaca aguda del lado derecho, la cual fue diagnosticada con un examen clínico que incluía ecografía percutánea y transrectal, y tratada con infiltraciones ecoguiadas de corticoides y aspirado de médula ósea. Un mes después de la última terapia, el caballo mostró una mejoría clínica en un 80% a 90% aproximadamente y retoma actividad física controlada.

Abstract Sacroiliac subluxation is a claudiogenic disease of the hind limbs that can present acutely or chronically. The cause of this pathology is mainly due to slipping, tripping, or falling of the hind limbs, the diagnosis is difficult to make due to the deep anatomical location of the joint, methods such as ultrasound and stress tests among others, are the procedures most used in the diagnosis of sacroiliac subluxation. As it is an alteration that can easily be confused with other pathological conditions of the spine, pelvis and / or the hind limbs, the diagnosis is often made by eliminating other causes of lameness. Conventional treatments are still proposed in the literature, however regenerative therapy is increasingly used as an option for the treatment of sacroiliac joint injuries. This report describes the case of a Creole horse that suffered an acute sacroiliac subluxation on the right side, which was diagnosed with a clinical examination that included percutaneous and transrectal ultrasound and treated with ultrasound-guided infiltrations of corticosteroids and cells of the bone marrow of the sternum without processing. One month after the last therapy, the horse showed an 80% to 90% recovery and resumed controlled physical activity.

Reproducibility of s2-alar iliac screw morphometric analysis / Reprodutibilidade da análise morfométrica do parafuso s2-asa do ilíaco

ABSTRACT Objective: To evaluate the reproducibility of a S2-alar iliac (S2AI) screw parameters measurement method by inter and intraobserver reliability. Methods: Cross-sectional study, considering computed tomography exams. Morphometric analysis was performed by multiplanar reconstructions. Screw length, diameter and trajectory angles were the studied variables. To analyze the measurements reproducibility, intraclass correlation coefficient (ICC) was used. Results: Interobserver reliability was classified as strong for screw shortest length (ICC: 0.742) and diameter (ICC: 0.699). Interobserver reliability was classified as moderate for screw longest length (ICC: 0.553) and for screw trajectory angles in the axial plane for the longest (ICC: 0.478) and for the shortest lengths (ICC: 0.591). Intraobserver reliability was interpreted as excellent for screw shortest (ICC: 0.932) and longest lengths (ICC: 0.962) and diameter (ICC: 0.770) and screw trajectory angles in the axial plane for the screw longest (ICC: 0.773) and shortest lengths (ICC: 0.862). There were weak interobserver and strong intraobserver reliabilities for trajectory angle in sagittal plane, but no statistical significance was found. Conclusion: Inter and intraobserver reliability of S2AI screw morphometric parameters were interpreted from moderate to excellent in almost all studied variables, except for the screw trajectory angle in the sagittal plane measurement. Level of Evidence IV, Diagnostic Studies - Investigating a Diagnostic Test.

RESUMO Objetivo: Avaliar a reprodutibilidade, por meio da concordância inter e intraobservador, de um método de aferição dos parâmetros sacropélvicos do parafuso S2-asa do ilíaco (S2AI). Métodos: Estudo transversal, considerando exames de tomografia computadorizada. A análise morfométrica foi feita por meio de reconstruções multiplanares. As variáveis estudadas foram: comprimento, diâmetro e ângulos de trajetória do parafuso S2AI. Para análise da reprodutibilidade das medidas, utilizou-se o coeficiente de correlação intraclasse (ICC). Resultados: A confiabilidade interobservador foi classificada como forte para o menor comprimento (ICC: 0,742) e diâmetro (ICC: 0,699). Em relação ao maior comprimento (ICC: 0,553) e aos ângulos de trajetória axial para o maior (ICC: 0,478) e para o menor comprimento (ICC: 0,591), a confiabilidade interobservador foi classificada como moderada. A confiabilidade intraobservador foi excelente para o menor (ICC: 0,932) e maior comprimentos (ICC: 0,962), diâmetro (ICC: 0,770) e ângulos de trajetória axial (ICC: 0,773 - maior comprimento; ICC: 0,862 - menor comprimento). Houve confiabilidade interobservador fraca e intraobservador forte para o ângulo de trajetória sagital, porém sem significância estatística. Conclusão: A correlação inter e intraobservador dos parâmetros morfométricos do parafuso S2AI mostrou-se de moderada a excelente em quase todas as variáveis estudadas, exceto para o ângulo de trajetória sagital. Nível de Evidência IV, Estudos diagnósticos - Investigação de um exame para diagnóstico.

Efficacy of TiRobot-assisted surgery by O-arm navigation for minimally invasive treatment of type C pelvic fractures / 中华创伤杂志

Objective:To evaluate the effectiveness of TiRobot-assisted surgery by O-arm navigation for minimally invasive treatment of type C pelvic fractures.Methods:A retrospective case control study was conducted on clinical data of 53 patients with type C pelvic ring fractures treated between January 2018 and September 2019 at Shanghai Tenth People’s Hospital. There were 29 males and 24 females，aged 20-68 years［（40.4 ± 15.5）years］. All were diagnosed with AO type C fractures. A total of 32 patients underwent minimally invasive internal fixation by TiRobot orthopedic system assisted with O-arm navigation（TiRobot group），and 21 patients were managed by minimally invasive internal fixation under the fluoroscopy guidance of the C-arm X-ray machine（control group）. The operation time，intraoperative blood loss，fluoroscopy time of screw and good and excellent rate of screw placement were recorded. One week after surgery，the pain intensity was assessed by visual analog scale（VAS），and the fracture reduction quality by Matta radiographic criteria. At the latest follow-up，the recovery of pelvic function was evaluated by Majeed criteria. Complications were recorded after operation and during the follow-up.Results:All patients were followed up for 12-15 months［（13.2 ± 0.3）months］. The operation time was（85.2 ± 6.9）minutes in TiRobot group and（101.0 ± 6.7）minutes in control group（ P < 0.05）. The intraoperative blood loss showed no significant difference between the two groups（ P > 0.05）. The fluoroscopy time of screw placement was 6（5，7）seconds in TiRobot group，compared to 10（10，15）seconds in control group（ P < 0.05）. In TiRobot group，the screw placement was excellent in 30 patients，good in 1，and fair in 1，with the excellent and good rate of 97%（31/32），while in control group，15 patients showed excellent placement of screws，2 good，and 4 fair，with the excellent and good rate of 76%（17/21）（ P < 0.05）. There was no significant difference in VAS between the two groups at postoperative one week（ P > 0.05）.At the latest follow-up，the pelvic reduction quality based on Matta radiographic criteria and pelvic function using Majeed criteria did not differ significantly between the two groups（ P > 0.05）. No complications occurred after operation and during the follow-up，such as loosening or breakage of screws，heterotopic ossification，vascular injury or nerve injury. Conclusion:For type C pelvic fractures，TiRobot-assisted minimally invasive internal fixation by O-arm navigation can shorten operation time and intraoperative fluoroscopy time，and improve the accuracy of screw placement when compared to C-arm fluoroscopy.

3D navigation versus C-arm fluoroscopy for placement of percutaneous double-segment long sacroiliac screws in treatment of injury to posterior pelvic ring / 中华创伤骨科杂志

Objective:To compare the efficacy of 3D navigation versus C-arm fluoroscopy for placement of percutaneous double-segment long sacroiliac screws in the treatment of injury to the posterior pelvic ring.Methods:A retrospective study was conducted in the 48 patients with pelvic fracture who had been treated surgically from February 2015 to October 2020 at Department of Orthopaedics, General Hospital of Central Command of PLA. The patients were divided into a navigation group and a fluoroscopy group according to their different auxiliary ways to assist screw placement. In the navigation group of 27 patients, there were 19 males and 8 females, with an age of (45.5±7.4) years; in the fluoroscopy group of 21 patients, there were 14 males and 7 females, with an age of (44.1±10.1) years. The 2 groups were compared in terms of placement time for each screw, fluoroscopy time for each screw, adjustments of guide wire, accuracy of screw position, quality of fracture reduction, fracture union time, pelvic function, and postoperative complications.Results:The 2 groups were comparable because there was no significant difference between them in the preoperative general data ( P>0.05). The placement time for each screw [(12.7±2.2) min], fluoroscopy time for each screw [(40.7±9.3) s] and adjustments of guide wire [1 (0,1) time] in the navigation group were significantly less than those in the fluoroscopy group [(23.7±3.6) min, (71.4±14.1)s and 5 (4,6) times] (all P<0.05); the assessment of screw placement in the former (49 excellent, 4 good and one poor cases) was significantly better than that in the latter (29 excellent, 8 good and 5 poor cases) ( P<0.05). The 48 patients were followed up for 8 to 25 months (mean, 13.1 months). There were no significant differences between the 2 groups in fracture union time, quality of fracture reduction or Majeed scores for the pelvic function (all P>0.05).Symptoms of injury to the L5 nerve root were observed in one patient in the fluoroscopy group; none of the patients reported postoperative complications like wound infection, screw loosening or breaking. Conclusions:Compared with C-arm fluoroscopy, 3D navigation may better assist placement of percutaneous double-segment long sacroiliac screws in the treatment of injury to the posterior pelvic ring, because 3D navigation can significantly shorten the time for screw placement and the fluoroscopy time for screw placement, reduce adjustments of guide wire, and improve accuracy of screw placement.

Clinical treatment of pelvic fracture complicated with anterior sacroiliac joint dislocation / 中华骨科杂志

Objective:To explore the clinical diagnosis and treatment experience of pelvic fracture complicated with anterior sacroiliac joint dislocation.Methods:The data of 19 patients with pelvic fracture and anterior sacroiliac joint dislocation admitted from June 2013 to September 2019 were retrospectively analyzed. There were 12 males and 7 females; aged 9-67 years, with an average of 28.0 years. There were 11 cases of traffic accident injury, 6 of falling injury and 2 of crashing injury caused by machine extrusion. According to the Tile classification, there were 8 cases of type C1, 2 of type C2, and 9 of type C3; 6 cases of modified mangled extremity severity score (MESS) were greater than or equal to 7, of which 2 cases underwent hip amputation, 4 cases underwent king-steelquis semipelvectomy. 13 cases underwent limb-salvage surgery, of which 3 cases underwent external fixation surgery, and the remaining 10 cases underwent open reduction and internal fixation with steel plate. The reduction quality was evaluated according to the Matta imaging criteria of pelvis, the pain was evaluated according to the visual analogue scale (VAS), and the pelvic function was evaluated according to the Majeed score.Results:The operation time was 2 to 4 hours, with an average of 3.2 hours; the intraoperative blood loss was 400 to 1 200 ml, with an average of 768.4 ml. The 18 surviving patients were followed up for 6 to 24 months, with an average of 11.6 months. One of the 6 amputation patients died one week after the operation due to septic shock and multiple organ failure. The overall survival rate of the patients was 94.7% (18/19), and the amputation rate was 31.6% (6/19). The pelvic fractures of the 18 surviving patients were all healed, and the fracture healing time was 3 to 6 months, with an average of 4.2 months. No delayed union or nonunion occurred. At the last follow-up of the 18 surviving patients, the VAS was 2.4±1.9 points (range, 0-6 points). Among them, there were no pain in 3 cases, mild pain in 9 cases and moderate pain in 6 cases. At the last follow-up, 13 patients undergoing limb salvage treatment evaluated the quality of reduction according to Matta imaging criteria. Among them, 6 cases were excellent, 4 were good, 2 were fair, and 1 was poor. The excellent and good rate was 76.9% (10/13). The Majeed functional score was 81.8±11.9 points (range, 53-95 points). Among them, 6 cases were excellent, 5 were good, 1 was fair, and 1 was poor. The excellent and good rate was 84.6% (11/13). In the limb salvage treatment group, 4 patients with lumbosacral nerve injury caused limited hip joint movement function, and unilateral lower limb sensation and movement were weakened. After neurolysis and nutritional support treatment, the patient's sensorimotor function was significantly improved.Conclusion:The mortality and disability rate of pelvic fractures combined with anterior sacroiliac joint dislocation is high. In order to save the patient's life, early diagnosis of limb injury and early surgical intervention should be performed. If necessary, hip disarticulation or king-steelquis should be selected.

3D printed hemipelvic prosthesis for treatment of pelvic malignant tumors resected via sacroiliac joint / 中华骨科杂志

Objective:To analyze the surgical techniques, surgical indications and early clinical effects of 3D printed hemipelvic prostheses in the reconstruction of pelvic malignant tumors resected by the sacroiliac joint.Methods:From January 2016 to March 2020, a retrospective analysis of 9 patients with malignant tumors involving pelvis I+II or I+II+III region were treated with sacroiliac joint osteotomy and 3D printed pelvic prosthesis reconstruction. There were 7 males and 2 females; their age was 51.1±10.5 years (range 27-66 years). Among them, 5 cases were chondrosarcoma, 1 case was pleomorphic undifferentiated sarcoma, 2 cases were metastatic renal cell carcinoma, and 1 case was metastatic primitive neuroectodermal tumor. Resection of pelvic area I+II or I+II+III were according to the extent of tumor involvement. During the resection of pelvic I region, osteotomy was done through sacroiliac joint surface, and 3D printed hemipelvic prosthesis that fits the sacral auricular surface was used for reconstruction. Postoperative imaging examination was used to evaluate the acetabular rotation center deviation of the pelvic prosthesis; the International Bone Tumor Society (Musculoskeletal Tumor Society, MSTS) function score was used for functional evaluation; the patient's oncology outcome and postoperative complications were evaluated.Results:All 9 patients successfully completed the operation. The operation time was 3.5-6 hours, with an average of 4.5 hours. The intraoperative blood loss was 800-3 000 ml, with an average of 1 400 ml. 3 patients underwent resection and reconstruction of pelvis I+II area, 4 patients underwent pelvic resection and reconstruction of I+II+III area, 2 patients underwent pelvic I+II+III area combined with proximal femur resection and reconstruction; all patients were followed up. The follow-up time was 6-50 months, with an average of 16 months. At the last follow-up of 9 patients, the MSTS score was 12-26, with an average of 20.2; the postoperative rotation center horizontal displacement distance was 10.67±7.12 mm, and the vertical displacement was 8.56±4.22 mm. One case of metastatic cancer was found to have multiple metastases throughout the body during chemotherapy 3 months after surgery, and died in 7 months after surgery; 1 case of pelvic metastatic renal cell carcinoma developed multiple metastases within one and a half years after surgery, controlled by targeted drugs, and survived with the tumor; the rest seven cases had no recurrence at the surgical site and no distant metastasis was found.Conclusion:The semipelvic prosthesis with 3D printed auricular surface has potential advantages in reconstructing the bone defect of the pelvis I+II or I+II+III area after the sacroiliac joint osteotomy. The short-term efficacy is relatively satisfactory, and the long-term efficacy remains to be further observed.

To evaluate clinical efficacy and surgical methods of sacroiliac joint dislocation with ipsilateral sacrosacral wing fracture / 中华骨科杂志

Objective:To investigate the surgical methods of sacroiliac joint dislocation with ipsilateral sacrosacral wing fracture through the lateral-rectus approach (LRA) for exposure, fracture reduction and fixation, and nerve exploration and decompression, and to evaluate its clinical efficacy.Methods:Data of 12 patients with sacroiliac joint dislocation and ipsilateral sacral wing fracture treated with LRA for exposure, reduction and fixation of sacroiliac wing fracture and sacroiliac joint dislocation, lumbosacral trunk nerve exploration and decompression (combined with lumbosacral trunk nerve injury) were retrospectively analyzed from January 2016 to July 2019. They were 3 males and 9 females, aged 34.35±16.32 years (13-58 years). The time from injury to operation was 29.25±25.49 d (7-96 d). By the Tile classification, there were 7 cases of type C1.3, 1 case of type C2, 4 cases of type C3. Among them, 8 cases were combined with ipsilateral or bilateral lumbosacral nerve injury. The grade of nerve injury: 6 cases of complete injury and 2 cases of partial injury. Interval time from injury to surgery: less than 1 week: 1 case, 1-2 weeks: 2 cases, 2-3 weeks: 4 cases, >3 weeks: 5 cases. Surgery was performed through LRA, the sacroiliac joint was exposed outside the peritoneum, and the sacral fracture and sacroiliac joint dislocation were reduced. At the same time, the lumbosacral nerve was decompressed and loosened for patients with lumbosacral nerve injury. Then the posterior ring was fixed with a sacroiliac screw or a transsacroiliac joint plate attached to the bony surface.Results:All the 12 cases underwent the operation successfully. The average surgical time was 172.08±36.8 min (range, 105-230 min) and the mean blood loss was 981.67±369.44 ml (range, 400-1 700 ml). Postoperative X-ray and CT indicated an excellent reduction of fracture. One patient with bladder dysplasia had wound fat liquefaction after operation, and no other surgery-related complications. During the follow-up period of 12-72 months, all sacral fractures healed, and the healing time was 7.7±3.38 weeks (6-12 weeks) without complications such as loss of fracture reduction and internal fixation failure. At the 1-year follow-up, 6 of the 8 patients with lumbosacral nerve injury recovered completely, one recovered partially, and the other one had no recovery without nerve exploration.Conclusion:LRA is an ideal surgical approach for treatment of sacroiliac joint dislocation complicated with ipsilateral sacral wing fracture and lumbosacral nerve injury, because it can well expose the medial pelvic joint from the sacroiliac joint to the symphysis pubis, allow direct release of the lumbosacral plexus nerve compressed and stretched, and together with traction of the lower limbs, lead to satisfactory fracture reduction.

Description of the Sacropelvic Parameters Measurement Method for S2-alar iliac Screw Insertion / Descrição do método de aferição dos parâmetros sacropélvicos para a inserção do parafuso S2-asa do ilíaco

Abstract Objective Description of the sacropelvic parameters measurement method for S2-alar iliac (S2AI) screw insertion. Methods Descriptive study of the method for measuring sacropelvic parameters for the insertion of the S2AI screw using computed tomography (CT). The data evaluated in multiplanar reconstructions were the parameters of the screw trajectory, including length, diameter and angles of the trajectory in the axial and sagittal planes. Results From the sagittal reconstruction, the axis of the series of axial slices is angled three-dimensionally so that it is possible to visualize the S2 vertebra, the screw entry point, and the anteroinferior iliac spine (AIIS) in the same plane. The entry point is demarcated at the midpoint between the dorsal foramina of S1 and S2. To measure the length of the screw, lines are drawn tangent to the inner and outer cortices of the iliac. The diameter is determined by the shortest distance between the inner and outer iliac faces minus half of the diameter of the screw chosen medially and laterally. The path angle in the axial plane is formed by the anteroposterior midline of the sacrum and the line of the screw length. The craniocaudal inclination angle in relation to the S1 plateau corresponds to the degree of inclination made in the sagittal plane to find the image in which the entry point and the AIIS are seen in the same plane. Conclusion It was possible to adequately assess, through multiplanar CT reconstructions, the sacropelvic parameters necessary for the safe insertion of the S2AI screw.

Resumo Objetivo Descrever como aferir os parâmetros sacropélvicos para a inserção segura do parafuso S2-asa do ilíaco (S2AI). Métodos Estudo descritivo do método de aferição dos parâmetros sacropélvicos para a inserção do parafuso S2AI por meio de tomografia computadorizada (TC). Os dados avaliados em reconstruções multiplanares foram os parâmetros da trajetória do parafuso, incluindo comprimento, diâmetro e ângulos de trajetória nos planos axial e sagital. Resultados A partir da reconstrução sagital, angula-se tridimensionalmente o eixo da série de cortes axiais de modo que seja possível visualizar a vértebra S2, o ponto de entrada do parafuso e a espinha ilíaca anteroinferior (EIAI) no mesmo plano. O ponto de entrada é demarcado no ponto médio entre os forames dorsais de S1 e S2. Para medir o comprimento do parafuso, traçam-se linhas tangenciando as corticais interna e externa do ilíaco. O diâmetro é determinado pela menor distância entre as tábuas interna e externa do ilíaco subtraindo metade do diâmetro do parafuso escolhido medialmente e lateralmente. O ângulo de trajetória no plano axial é formado pela linha média anteroposterior do sacro e a linha do comprimento do parafuso. O ângulo de inclinação craniocaudal em relação ao platô de S1 corresponde ao grau de inclinação feito no plano sagital para encontrar a imagem em que o ponto de entrada e a EIAI são vistos no mesmo plano. Conclusão Foi possível aferir adequadamente, por meio de reconstruções multiplanares de TC, os parâmetros sacropélvicos necessários para a inserção segura do parafuso S2AI.