Optimal insertion positions of anterior-posterior orientation sacroiliac screw.

PURPOSE: To explore the optimal insertion positions of anterior-posterior orientation sacroiliac screw (AP-SIS). METHODS: Pelvic CT data of 80 healthy adults were employed to measure the anatomical parameters including the insertable ranges of S1 and S2, the length, width and height of the channel with three different horizontal and vertical anterior insertion points starting from the ilium-acetabular recess. To compare pelvic stability by replicating a type C Tile lesions, fifteen synthetic pelvises were fixed with an anterior plate and a posterior AP-SIS employing different anterior insertion points, the whole specimen displacements and shifts in the sacroiliac gap under a cyclic vertical load of 300 N in a biomechanical machine recorded. RESULTS: The posterior and anterior insertable ranges averaged 17.9 × 8.5mm2 and 47.1 × 21.2 mm2, respectively. The channel lengths for three horizontal anterior insertion points gradually decreased from front to back with significant difference (p < 0.05), whereas the width and height for three horizontal anterior insertion points and the parameters for the three vertical anterior insertion points were similar (p > 0.05). The displacements and shifts for three horizontal insertion points gradually increased from front to back (p < 0.05) whereas the measurements involving the three vertical insertion points were similar (p > 0.05). CONCLUSION: The posterior insertable range is small, where the center between adjacent nerve roots (foramens) is the optimal posterior insertion point. The anterior insertable range is large, where the iliac-acetabular recess is the optimal anterior insertion point for S1 and S2, providing the longest channel and best stability.

Guidance for dysmorphic sacrum fixation with upper sacroiliac screw based on imaging anatomy study: techniques and indications.

OBJECTIVE: This study aimed to investigate the techniques and indications of upper sacroiliac screw fixation for the dysmorphic sacrum. METHODS: The dysmorphic sacra were selected from 267 three-dimensional pelvic models. The dysmorphic sacra which couldn't accommodate a 7.3 mm upper trans ilio-sacroiliac screw were classified as the main dysmorphic sacra. Then, the size of the bone corridor, the length of the screw in the corridor, and the orientation of the screw were measured. The insertion point on the sacrum was identified by two bone landmarks. RESULTS: totally, 30.3% of sacra were identified as the main dysmorphic sacra. The inclinations of the screw oriented from posterior to anterior were (21.80 ± 3.56)° for males and (19.97 ± 3.02)° for females (p < 0.001), and from caudal to cranial were (29.97 ± 5.38)° for males and (28.15 ± 6.21)° for females (p = 0.047). The min diameters of the corridor were (16.31 ± 2.40) mm for males and (15.07 ± 1.58) mm for females (p < 0.001). The lengths of the screw in the Denis III zone were (14.41 ± 4.40) mm for males and (14.09 ± 5.04) mm for females (p = 0.665), and in the Denis II+III zones were (36.25 ± 3.40) mm for males and (38.04 ± 4.60) mm for females (p = 0.005). The rates of LP-PSIS/LAIIS-PSIS were (0.36 ± 0.04) for males and (0.32 ± 0.03) for females (t = 4.943, p < 0.001). The lengths of LPM were (8.81 ± 5.88) for males and (-4.13 ± 6.33) for females (t = 13.434, p < 0.001). CONCLUSION: When the sacrum has the features of "sacrum not recessed" and/or "acute alar slope", the conventional trans ilio-sacroiliac screw couldn't be placed safely. The inclination oriented from posterior to anterior and from caudal to cranial are approximately 20° and 30°, respectively. The bone insertion point locates in the rear third of the anterior inferior iliac spine to the posterior superior iliac spine. The sacroiliac screw is not recommended to fix the fractures in Denis III zone.

An evaluation of the inlet obturator oblique view for sacroiliac and transsacral screw placement.

INTRODUCTION: Between 2005 and 2017, the number of closed reduction and internal fixation of pelvic ring injuries increased by 1116%. Percutaneous fixation is currently the only minimally invasive technique that can stabilize the posterior elements of the pelvis. The purpose of this study was to investigate the utility of the inlet obturator oblique view (IOO) with the hypothesis that the IOO view will improve the accuracy of sacroiliac and transsacral screw placement in the S1 or S2 body and improve the accuracy of assessing whether the implant is fully seated against the outer cortex of the ilium. MATERIALS AND METHODS: Ten male pelvic training models were used. Thirty-six screw configurations were inserted by a fellowship trained orthopedic trauma surgeon in appropriately and inappropriately placed sacroiliac and transsacral screw configurations. These configurations were imaged using fluoroscopy in different planes and saved for survey. RESULTS: Fourteen orthopedic professionals reviewed 313 fluoroscopic images. Interrater reliability demonstrated marked improvement in assessment of whether the screw head was seated against the outer cortex of the ilium with the IOO view (kappa = 0.841, without IOO kappa = 0.027). There was a statistically significant difference in overall accuracy (p value < 0.001, OR = 1.57, 95% CI = 1.35-1.84) and whether the screw head was seated (p value < 0.001, OR = 8.14, 95% CI = 5.52-11.99) when compared with and without the IOO view (accuracy with IOO view: 85%, accuracy without IOO view: 78.26%; screw seated with IOO view: 93.93%, screw seated without IOO view: 65.54%). There was no significant difference (p value 0.465, OR = 1.13, 95% CI = 0.82-1.55) determining if the screw was in a safe position (safe with IOO view: 84.64%, safe without IOO view: 83.04%). CONCLUSIONS: Our findings demonstrate that misinterpretation of sacroiliac and transsacral screw placement can occur with the standard fluoroscopic imaging. We suggest the addition of the IOO view increases the overall accuracy of screw placement and whether the screw head is fully seated against the outer table of the ilium. This in turn can improve fixation and potentially improve patient outcomes and decrease adverse events.

Combined anterior and posterior ring fixation versus posterior ring fixation alone in the management of unstable Tile B and C pelvic ring injuries: A randomized controlled trial.

PURPOSE: Combined anterior and posterior ring (APR) fixation is classically performed in Tile B2 and C1 injuries to achieve superior biomechanical stability. However, the posterior ring (PR) is the main weight bearing portion that is responsible for weight transmission from the upper parts of the body to the lower limbs through the sacrum and the linea terminalis. It is hypothesized that isolated PR fixation can achieve comparable radiological and clinical outcomes to APR fixation. Therefore, we conducted this study to compare the two fixation principles in managing Tile B2 and C1 injuries. METHODS: Our study included 20 patients with Tile B2 injuries and 20 patients with Tile C1 injuries. This study was a randomized control single-blinded study via computerized random numbers with a 1:1 allocation by using random block method. The study was performed at a level one trauma center. A total of 40 patients with Tile B2 and C1 injuries underwent combined APR or isolated PR fixation (Group A and B, respectively). Matta & Tornetta radiological principles and Majeed pelvic scoring system were used for the assessment of primary outcomes and postoperative complications. Secondary outcomes included operative time, amount of blood loss, intraoperative assessment of reduction, need of another operation, length of hospital stay, ability to weight bear postoperatively and pain control metrics. We used student t-test to compare the difference in means between two groups, and Chi-square test to compare proportions between two qualitative parameters. We set the confidence interval to 95% and the margin of error accepted to 5%. So, p ≤ 0.05 was considered statistically significant. RESULTS: The mean follow-up duration was 18 months. The operative time (mean difference 0.575 h) and the intraoperative blood loss (mean difference 97.5 mL) were lower in Group B. Also, despite the higher frequency of rami displacement before union in the same group, there were no significant differences in terms of radiological outcome (excellent outcome with OR = 2.357), clinical outcome (excellent outcome with OR = 2.852) and postoperative complications assessment (OR = 1.556) at last follow-up. CONCLUSION: The authors concluded that isolated PR fixation could favorably manage Tile B2 and C1 pelvic ring injuries with Nakatani zone II pubic rami fractures and intact inguinal ligament. Its final radiological and clinical outcomes and postoperative complications were comparable to combined APR fixation, but with less morbidity (shorter operation time, lower amount of blood, and no records of postoperative wound infection).

Is a Washer a Mandatory Component in Young Trauma Patients with S1-S2 Iliosacral Screw Fixation of Posterior Pelvis Ring Injuries? A Biomechanical Study.

Background and purpose: Cannulated screws are standard implants for percutaneous fixa-tion of posterior pelvis ring injuries. The choice of whether to use these screws in combination with a washer is still undecided. The aim of this study was to evaluate the biomechanical competence of S1-S2 sacroiliac (SI) screw fixation with and without using a washer across three different screw designs. Material and Methods: Twenty-four composite pelvises were used and an SI joint injury type APC III according to the Young and Burgess classification was simulated. Fixation of the posterior pelvis ring was performed using either partially threaded short screws, fully threaded short screws, or fully threaded long transsacral screws. Biomechanical testing was performed under progressively increasing cyclic loading until failure, with monitoring of the intersegmental and bone-implant movements via motion tracking. Results: The number of cycles to failure and the corresponding load at failure (N) were significantly higher for the fully threaded short screws with a washer (3972 ± 600/398.6 ± 30.0) versus its counterpart without a washer (2993 ± 527/349.7 ± 26.4), p = 0.026. In contrast, these two parameters did not reveal any significant differences when comparing fixations with and without a washer using either partially threaded short of fully threaded long transsacral screws, p ≥ 0.359. Conclusions: From a biomechanical perspective, a washer could be optional when using partially threaded short or fully threaded long transsacral S1-S2 screws for treatment of posterior pelvis ring injuries in young trauma patients. Yet, the omission of the washer in fully threaded short screws could lead to a significant diminished biomechanical stability.

Complications of conventional percutaneous sacroiliac screw fixation of traumatic pelvic ring injuries: a systematic review and meta-analysis.

OBJECTIVES: The objective of this review was to present a thorough overview of the complications associated with conventional percutaneous sacroiliac screw fixation to identify areas for improvement in surgical technique and patient selection. METHODS: PubMed/Medline, Web of Science, Embase, Ovid, Cochrane library, and Google Scholar were systematically searched for original human studies reporting on complications of conventional percutaneous sacroiliac fixation in traumatic pelvic ring injuries from January 1, 2000, to April 30, 2022. The main meta-analysis was based on the random effect model to pool all complications reported in the included studies. The results were reported as weighted proportions with 95% confidence intervals. This review was conducted in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. RESULTS: A total of 56 studies with 3644 screws (2871 procedures) met the inclusion criteria, with a mean age of 40.5 years. The most frequently reported complications were screw malposition with a weighted proportion of 6% (95% CI: 5-9%) and involved 189 out of 3644 screws, persistent pain following the procedure with a weighted proportion of 3% (95% CI: 2-4%) and affected 98 out of 2871 patients, and nerve injury, which had a weighted proportion of 2% (95% CI: 1-3%) and was observed in 41 out of 2871 procedures. The L5 and S1 nerve roots were more frequently affected. Revision surgery was required for 184 out of 2871 patients with a weighted proportion of 5% (95% CI: 3-7%). The primary reason for the revision was persistent pain after the initial procedure, which affected 74 out of 184 patients, with a weighted proportion of 2.0% (95% CI: 1.2-2.8%). CONCLUSIONS: This study showed that screw malposition, the need for revision surgery, persistent pain, and nerve injuries were the most frequent complications following conventional percutaneous sacroiliac screw fixation. However, these results must be interpreted in context due to confounding factors, including the lack of high-quality studies and the absence of uniformity in defining some complications across studies.

A standardized method of measuring screw breach on postoperative computed tomography scans following percutaneous fixation of the posterior pelvic ring.

PURPOSE: To assess the reliability of a standardized measurement of screw breach on postoperative computed tomography (CT) scans following percutaneous fixation of the posterior pelvic ring. METHODS: Three orthopedic trauma surgeons independently utilized a standardized method of measuring posterior pelvic ring screw breaches on post-operative CT scan images. Breaches were measured as a continuous variable on sagittal images reformatted to be perpendicular to the screw on axial images. The inter-rater and intra-rater reliability of screw breach distance measurements was assessed. RESULTS: Measurements were performed on 42 screws in 20 patients. Screw types included S1-iliosacral (IS) (n = 16), S1-transsacral (TS) (n = 8), S2-IS (n = 2), and S2-TS (n = 16). Patients with varying degrees of screw breaches were chosen to test measurements across breach severities, including 0 mm (n = 10), ≤ 2 mm (n = 12), > 2 to 4 mm (n = 11), and > 4 mm (n = 9). The mean difference and 95% confidence interval (CI) between screw breach measurements between the three surgeons was - 0.13 mm (CI - 0.48 to 0.20), 0.05 mm (CI - 0.6 to 0.7), and 0.18 mm (CI - 0.47 to 0.85), respectively. The inter-rater reliability of the measurements was considered excellent (intraclass correlation coefficient (ICC), 0.93). The mean intra-rater reliability for the observers was considered good (ICC 88.5, CI 82 to 95). CONCLUSIONS: This simple standardized method of measuring screw breaches had excellent inter-rater reliability and would support comparisons of screw breach severity across studies. LEVEL OF EVIDENCE: Level III.

Radio-anatomical study of anterior-posterior placement sacroiliac screw channel.

PURPOSE: The outlet of the classic sacroiliac screw (SIS) cannot be precisely controlled by aiming devices, which may lead to malpositioned implants and neurovascular and visceral injury. This study aimed to radio-anatomically measure the parameters of the channel for anterior-posterior placement SIS (AP-SIS), which can be placed percutaneously with an aiming device. METHODS: Pelvic CT scan data of 80 healthy adults (40 males and 40 females) with an average age of 45 years (range 20-70 years) were collected. The length (L), width (W), height (H), cortical bone spacing (M), camber angle (E), anteversion angle (F), cross-sectional safety angle (P) and sagittal safety angle (Q) of the channel were measured by CT or Mimics software. RESULTS: The L, W, H, M, E, F, P and Q measures of S1 were 109.2 ± 8.0 mm, 18.5 ± 1.9 mm, 21.7 ± 1.7 mm, 8.1 ± 0.4 mm, 44.2 ± 3.2°, 42.4 ± 3.6°, 16.8 ± 1.1°, and 19.4 ± 2.0°, respectively, for S1, and 113.5 ± 9.4 mm, 18.2 ± 1.5 mm, 21.7 ± 1.7 mm, 7.7 ± 0.4 mm, 44.7 ± 3.2°, 31.2 ± 2.7°, 13.8 ± 1.0° and 15.4 ± 1.4°, respectively, for S2. Of the L measures, the intra-iliac segment was slightly longer than the intra-sacral segment. All parameters showed significant sex-related differences (p < 0.05). CONCLUSION: The AP-SIS channels of S1-2 have sufficient width and length to accommodate a cancellous screw with a Φ 7.0-8.0 mm and a length 90-130 mm. The intra-iliac segment is a long channel screw with better mechanical properties over classic SIS.

Breakage risk of different sacroiliac screws in unilateral sacral fractures a finite element analysis.

OBJECTIVE: To compare the breakage risk of lengthened sacroiliac screws and ordinary sacroiliac screws to treat unilateral vertical sacral fractures and provide a reference for clinical application. METHODS: A finite element model of Tile C pelvic ring injury (unilateral type Denis II fracture of the sacrum) was produced. The sacral fractures were fixed with a lengthened sacroiliac screw and ordinary sacroiliac screw in 6 types of models. The maximal von Mises stresses and stress distributions of the two kinds of screws when standing on both feet were measured and compared. RESULTS: The maximal von Mises stress of the lengthened screw was less than that of the ordinary screw. Compared with ordinary screw, the stress distribution in the lengthened screw was more homogeneous. CONCLUSIONS: The breakage risk of screws fixed in double segments is lower than that of screws fixed in single segments, the breakage risk of lengthened screws is lower than that of ordinary screws, and the breakage risk of screws fixed in S2 segments is lower than that of screws fixed in S1 segments.

O-arm navigation for sacroiliac screw placement in the treatment for posterior pelvic ring injury.

PURPOSE: This study aims to investigate the application value of O-arm navigation system in sacroiliac screw placement for the treatment of unstable pelvic ring injury. METHODS: A total of 40 patients (mean age = 30.75 ± 14.99 years, 25 males, 15 females) were included. From January 2016 to July 2018, 40 patients with posterior pelvic ring injury treated in our hospital were included. Of them, 19 patients underwent O-arm navigation for screw placement (O-arm group) while the other 21 received C-arm fluoroscopy guidance (C-arm group) for sacroiliac screw placement. Intraoperative outcomes and the outcome of screw placement were compared between groups. The quality of radiological images was assessed by Matta's radiological outcome grade. The outcome of complex pelvic fracture treatment was evaluated by Majeed Functional score. RESULTS: All demographic and clinical characteristics were comparable between the two groups. Compared with the C-arm groups, the O-arm group had a shorter surgery time (33.19 ± 3.14 vs. 48.35 ± 4.38 min, P < 0.001), a higher overall good outcome "excellent + good" rate of screw placement (95.45% vs. 73.91%, P < 0.05), and a significantly higher Majeed Functional score better outcome of complex pelvic fracture treatment at 1 and 3 months postoperation (both P < 0.05). CONCLUSION: Our results demonstrated that O-arm navigation system is feasible and safe for the treatment of posterior pelvic ring injury and can effectively improve the accuracy and safety of sacroiliac screw placement, shorten the operation time, and help rapid postoperative functional recovery.

[Trends in the surgical treatment of fractures of the pelvic ring : A nationwide analysis of operations and procedures code (OPS) data between 2005 and 2017]. / Trends in der operativen Therapie von Frakturen des Beckenrings : Eine bundesweite Analyse von OPS-Daten zwischen 2005 und 2017.

AIM: The aim of this study was to analyze the epidemiological trends and incidences in inpatient pelvic surgery in the period from 2005 to 2007. METHOD: Approximately 194 million anonymized diagnosis-related groups (DRG) inpatient records were collected by the German Federal Statistical Office between 2005 and 2017. These data were screened for pelvic procedures, gender and age of the patients. Statistical testing was performed using the χ2-test and Mann-Whitney U-test (p < 0.05). RESULTS: Between 2005 and 2017 the number of closed reduction and internal fixation of the pelvic ring with screw fixation increased by +1116%. The use of screw fixation for closed reduction and internal fixation of the sacroiliac joint increased by +800%. The number of cases of open reduction and internal fixation of fractures of the pelvic ring and pelvic rim increased by +185% and reposition with external fixator increased by +188%. In 2005 more surgical procedures were undertaken in male inpatients, whereas more surgical procedures were undertaken in female inpatients in 2017. In general, a large increase in the number of pelvic procedures was observed in the group of patients >50 years old. CONCLUSION: There was an increase in the number of all analyzed pelvic procedures between 2005 and 2017. Especially the use of screw fixation increased. The introduction of new techniques (e.g. screw fixation of the sacroiliac joint) and progress and innovation in the field of three-dimensional navigation techniques, the demographic trend, greater mobility and higher demands on functionality of older patients might explain this increase in pelvic procedures.

Comparative study of sacroiliac screw placement guided by 3D-printed template technology and X-ray fluoroscopy.

OBJECTIVE: To compare the clinical effect of 3D-printed template technology with X-ray fluoroscopy in assisting surgery for sacroiliac screws placement. DESIGN: Institutional review board-approved retrospective analysis. PATIENTS: The clinical data of 31 cases of sacroiliac complex injury between January 2015 and December 2016 were analyzed. There were 16 patients, males 11 and females 5, who underwent surgery assisted by 3D-printed template in template group, and that of contemporaneous 15 patients, males 11 and females 4, who underwent traditional surgery were gathered as fluoroscopy group. All those patients were followed up for more than 6 months. MAIN OUTCOME MEASURES: The operation time and X-ray fluoroscopy times for each screw placement, and the Matta and Majeed score were analyzed and the difference between the two group was tested. RESULTS: All cases were followed up for 6-20 months, average 11.4 ± 0.6 months. In template group, 19 screws were implanted. Each screw spent 25-38 min, average 27.2 ± 5.3 min, and need 2-5 times fluoroscopy, average 2.7 ± 0.5. The fracture reduction quality was evaluated by Matta score scale: excellent 10, well 4, fair 2, good rate 87.5%; and pelvic function were evaluated by Majeed score scale: excellent 11, well 3, fair 2, and good rate 87.5%. In fluoroscopy group, 17 screws were implanted. Each screw spent 45-70 min, average 60.3 ± 5.8 min, and needs 11-23 times fluoroscopy, average 15.4 ± 3.5. The fracture reduction quality was evaluated by Matta score scale: excellent 7, well 6, fair 2, and good rate 86.7%; and pelvic function was evaluated by Majeed score scale: excellent 6, well 6, fair 3, and good rate 80.0%. The difference in operation time, X-ray fluoroscopy times between template group and fluoroscopy group had statistical significance. But the Matta and Majeed score had no difference between two groups. CONCLUSION: Compared with traditional surgery, 3D-printed template technology-assisted surgery for sacroiliac screws placement in sacroiliac complex injury patients possesses advantage such as shortened operation time and reduced X-ray exposure times. This technology improves the safety profile of this operation and should be further studied in future clinical applications.

[U-shaped fractures of the sacrum-what is the correct treatment? : A presentation of three cases]. / U-Frakturen des Os sacrum ­ Wie therapiert man richtig? : Eine Präsentation dreier Fälle.

BACKGROUND: Sacral U­shaped fractures are rare but severe injuries. Due to the resulting spinopelvic dissociation they are highly unstable. Reduction and stabilization are usually required and decompression may be necessary due to frequent concomitant neurological injuries. In the literature there is no consensus with respect to the selection of the surgical approach. CASE PRESENTATIONS: After a road traffic accident an 18-year-old woman suffered a U-fracture of the sacrum type II according to Roy-Camille and was treated with bilateral double sacroiliac screw osteosynthesis and sacral laminectomy. A 76-year-old man with a U­fracture type I according to Roy-Camille after falling down the stairs was treated by lumbopelvic fixation. A 24-year-old man with U­fracture type II according to Roy Camille after a road accident was treated with triangular vertebropelvic stabilization and sacral laminectomy. For all patients the outcome was good. CONCLUSION: Surgical treatment is necessary, with minimally invasive techniques offering advantages over open surgery. A distinction must be made between lumbopelvic fixation and posterior pelvic ring fixation. Multiple aspects must be taken into consideration of the indications when selecting the surgical technique.

[Study on the precision of the robot-assisted sacroiliac screw placement].

Objective: To evaluate the precision of the robot-assisted sacroiliac screw placement for posterior pelvis injury and the impacting factors. Methods: The clinical data of twenty-four cases of posterior pelvic fractures treated by percutaneous sacroiliac screw placement in Yantai shan Hospital from August 2016 to May 2018 were studied retrospectively. There were 17 males and 7 females with a mean age of 44.1 years (ranged from 17 to 71 years). According to AO classification, 17 cases were type B fractures (9 cases of type B1 and 8 type B2), and 7 cases were type C factures (3 cases of type C1, 2 type C2 and 2 type C3). All cases were treated by robot-assisted percutaneous sacroiliac screw placement (AO cannulated screws with a diameter of 7.3 mm). In the posterior pelvic surgeries for the 24 cases, 26 S(1) sacroiliac screws fixations and 18 S(2) sacroiliac screw fixations were placed in total, with single S(1) segmental fixation in 8 cases, single S(2) segmental fixation in 3 cases, S(1) and S(2) combined fixation in 13 cases, S(1) unidirectional one-sided fixation in 18 cases, S(1) bidirectional two-sided fixation in 3 cases, S(2) unidirectional one-sided fixation in 14 cases, S(2) bidirectional two-sided fixation in 2 cases and S(1) unidirectional double screws fixation in 2 cases. X-ray and CT examinations were taken for all 24 cases after operation. The visual analogue scale (VAS) of pain were performed before and after the operation. Results: All the sacroiliac screws were successfully implanted at once as planned with the assistance of the robot. The postoperative X-ray films and CT showed that none of the sacroiliac screws broke through the sacral body and the contralateral sacral wing's frontal cortex nor did they stray into the sacral canal and the intervertebral space. In 3 cases, the sacroiliac screws went closely against and wore out the front edge of iliac cortical density line and sacral alar slope and finally re-entered the sacral body. In 3 cases, sacroiliac screws touched upon the sacral nerve canals but did not break through the nerve canals. The mean VAS of pain was improved from 7.1 points (4-10 points) before the operation to 1.9 points (0-3 points) after. Conclusions: The robot-assisted sacroiliac screw placement shows high precision, and hence is worthy of clinical promotion; however the primary role of the surgeon could not be replaced.

Rate of intraoperative problems during sacroiliac screw removal: expect the unexpected.

BACKGROUND: The indications for sacroiliac screw (SI) removal have been under debate. Data on complication rates of SI screw removal is missing in the current literature. The objective of this study was to compare the rate of intra- and perioperative problems and complications during SI screw removal to those with SI screw fixation. METHODS: A retrospective observational study with two interventions in the same cohort was performed. Consecutive patients who underwent both sacroiliac screw fixation for an isolated fracture of the pelvic ring and removal of the same implants between November 2008 and September 2015 (n = 19; age 57.3, SD 16.1 years) were included. Intraoperative technical problems, postoperative complications, duration of surgery, and radiation dose were analysed. RESULTS: Intraoperative technical problems occurred in 1/19 patients (5%) during SI screw fixation and in 7/19 cases (37%) during SI screw removal (p = .021). Postoperative complications were seen in 3/19 patients after SI screw fixation and in 1/19 patients after SI screw removal (p = 0.128). The surgical time needed per screw was longer for screw removal than for implantation (p = .005). The amount of radiation used for the whole intervention (p = .845) and per screw (p = .845) did not differ among the two interventions. CONCLUSIONS: Intraoperative technical problems were more frequent with SI screw removal than with SI screw fixation. Most of the intraoperative technical problems in this study were implant-related. They resulted in more surgical time needed per screw removed but similar radiation time.

[Robot assisted sacroiliac screw placement with a modified method of screw path planning].

Objective: To introduce a robot-assisted modified method of sacroiliac screw path planning in order to reduce the incidence of screw misplacement. Methods: The study involved 13 patients suffering from posterior pelvic injuries treated by percutaneous sacroiliac screw in Yantai Shan Hospital from August 2016 to May 2018. The patients included 9 males and 4 females, aged from 18 to 70 years (mean age 46.2 years). Causes of injury were traffic accidents (n=7), crushing injury (n=4) and fall from height (n=2). According to AO classification, 8 cases were classified with type B fractures (3 with type B1 and 5 with type B2), and 5 cases with type C fractures (2 with type C1, 1 with type C2, 2 with type C3). All the patients were treated by robot-assisted percutaneous sacroiliac screws (AO cannulated screws with a diameter of 7.3 mm) with an improved method of screw path planning. The screw placement time, blood loss, postoperative neurological, vascular and visceral function etc were observed. X-ray and CT were checked in the follow-up after the operation. Visual analogue scale (VAS) score was used to assess the pain degree of patients one week after the surgery. Results: All the sacroiliac screws were successfully implanted once with the robot-assisted improved method of screw path planning. The mean placement time of single screw was 15.9 min and the mean blood loss for single screw placement was less than 1 ml. No clinical manifestations of injuries of blood vessels, internal organs and lumbosacral nerve was found after the operation. The postoperative X-ray films and CT showed that none of the sacroiliac screws wore out the sacral body or the sacral wing's frontal cortex. Also, it was found that none of the sacroiliac screws strayed into the sacral canal and the intervertebral space. The mean VAS score decreased from preoperative 6.9 (4-10) to postoperative 1.8(0-3). Conclusion: The robot-assisted improved method of screw path planning contributes to safe and accurate sacroiliac screw placement.

In-screw polymethylmethacrylate-augmented sacroiliac screw for the treatment of fragility fractures of the pelvis: a prospective, observational study with 1-year follow-up.

BACKGROUND: The incidence of pelvic ring fractures in the elderly significantly increased. Because of persistent pain and immobilization associated with this injury, surgical treatment is recommended. To minimise comorbidities and surgical risk, percutaneous techniques are becoming more relevant. In-screw cement augmentation of sacroiliac screw fixation is a promising procedure; however, clinical follow-up data remain scarce. This study investigated the safety and possible complications of the procedure along with a 1-year follow-up. METHODS: Thirty-four patients (treated with 43 screws) were prospectively included. Data on patients' age and sex, the mechanism of accident, fracture pattern, duration of hospital stay, surgery and adverse events were recorded. Data were obtained postoperatively on the reduction of pain and complications, such as infection, cement leakage and neurological deficits, and at 1-year follow-up on pain, quality of life according to the 12-Item Short Form Survey and mobility. Implant failure was defined as retraction or dislocation of screws and was also documented. RESULTS: Screw-related complications occurred with 2 of 43 screws. None of these complications were related to cement augmentation. In-hospital adverse events occurred in 6 of 34 patients. Postoperative pain, measured by the visual analogue scale, was significantly reduced from 6.7 ± 1.4 preoperatively to 2.7 ± 1.0 postoperatively (p < 0.001). Although patients complained of pain at the 1-year follow-up, they reported a significant decline compared with pain at admission (3.4 ± 2.3; p < 0.001). Results on the quality of life were comparable with those for the age- and gender matched German population. All patients were mobile, and no implant failure was detected. CONCLUSIONS: The results indicate that in-screw augmented sacroiliac screw fixation for fragility fractures of the pelvis is a safe technique. Pain was significantly reduced immediately after surgery compared to the preoperative state. Furthermore, significant pain reduction after one year compared to the preoperative state and quality of life was comparable to the age- and gender- matched German population. Thus, we recommend in-screw augmentation for screw fixation for sacral fragility fractures of the pelvis following failed conservative treatment.

[Efficacy of Sacroiliac Joint Anterior Approach with Double Reconstruction Plate and Computer Assisted Navigation Percutaneous Sacroiliac Screw for Treating Tile C1 Pelvic Fractures].

OBJECTIVE: To compare the efficacy of sacroiliac joint anterior approach with double reconstruction plate and computer assisted navigation percutaneous sacroiliac screw for treating Tile C1 pelvic fractures. METHODS: Fifty patients with pelvic Tile C1 fractures were randomly divided into two groups ( n=25 for each) in the orthopedic department of West China Hospital of Sichuan University from December 2012 to November 2014. Patients in group A were treated by sacroiliac joint dislocation with anterior plate fixation. Patients in group B were treated with computerized navigation for percutaneous sacroiliac screw. The operation duration,intraoperative blood loss,incision length,and postoperative complications (nausea,vomiting,pulmonary infection,wound complications,etc.) were compared between the two groups. The postoperative fracture healing time,postoperative patient satisfaction,and postoperative fractures MATTA scores (to evaluate fracture reduction),postoperative MAJEED function scores,and SF36 scores of the patients were also recorded and compared. RESULTS: No significant differences in baseline characteristics were found between the two groups of patients. All of the patients in both groups had their operations successfully completed. Patients in group B had significantly shorter operations and lower intraoperative blood loss,incision length and postoperative complications than those in group A ( P<0.05). Patients in group B also had higher levels of satisfaction than those in group A ( P<0.05). No significant differences were found between the two groups in postoperative followup time,fracture healing time,postoperative MATTA scores,postoperative MAJEED function scores and SF36 scores ( P>0.05). CONCLUSION: Sacroiliac joint anterior approach with double reconstruction plate and computer assisted navigation percutaneous sacroiliac screws are both effective for treating Tile C1type pelvic fractures,with similar longterm efficacies. However,computer assisted navigation percutaneous sacroiliac screw has the advantages of less trauma,less bleeding,and quicker.

[Advances in Diagnosis and Treatment of Posterior Distal Injury of Pelvic Fracture].

Pelvic fracture is one of the common diseases of traumatic orthopedics. With the increase of accidents such as traffic accidents,high craters and crush injuries in China,the incidence of pelvic fractures is also increasing year by year. Since pelvic bones and the ligament structure are close to neurovascular,cavity organs and the urogenital structure,early diagnosis and treatment of pelvic fractures is essential for preventing early complications and late sequelae. The treatment of pelvic ring injury has been the focus of pelvic fracture treatment,which determines the outcome of treatment. The application of external fixation and internal fixation to pelvic fracture is still subject to ongoing debate. For unstable pelvic ring injury,emergency external fixation plays a very important role. Pelvic ring injury is often accompanied with nerve injury (lumbosacral plexus injury),which often leads to pain,dysfunction and other complications. Because of its refractory,extensive studies have been undertaken to identify clinical innovations that may be able to repair nerve damage and reduce complications. These research advances can help improve the diagnosis and treatment of pelvic fractures and patient survival and prognosis.

Precision insertion of percutaneous sacroiliac screws using a novel augmented reality-based navigation system: a pilot study.

PURPOSE: Augmented reality (AR) enables superimposition of virtual images onto the real world. The aim of this study is to present a novel AR-based navigation system for sacroiliac screw insertion and to evaluate its feasibility and accuracy in cadaveric experiments. METHODS: Six cadavers with intact pelvises were employed in our study. They were CT scanned and the pelvis and vessels were segmented into 3D models. The ideal trajectory of the sacroiliac screw was planned and represented visually as a cylinder. For the intervention, the head mounted display created a real-time AR environment by superimposing the virtual 3D models onto the surgeon's field of view. The screws were drilled into the pelvis as guided by the trajectory represented by the cylinder. Following the intervention, a repeat CT scan was performed to evaluate the accuracy of the system, by assessing the screw positions and the deviations between the planned trajectories and inserted screws. RESULTS: Post-operative CT images showed that all 12 screws were correctly placed with no perforation. The mean deviation between the planned trajectories and the inserted screws was 2.7 ± 1.2 mm at the bony entry point, 3.7 ± 1.1 mm at the screw tip, and the mean angular deviation between the two trajectories was 2.9° ± 1.1°. The mean deviation at the nerve root tunnels region on the sagittal plane was 3.6 ± 1.0 mm. CONCLUSIONS: This study suggests an intuitive approach for guiding screw placement by way of AR-based navigation. This approach was feasible and accurate. It may serve as a valuable tool for assisting percutaneous sacroiliac screw insertion in live surgery.