A new approach for percutaneous ilio-sacral screw fixation: CT-based pre-operative planning with conventional fluoroscopy to reduce malposition rate and operating time.

PURPOSE: Percutaneous ilio-sacral screw (ISS) insertion using conventional C-arm fluoroscopy has been a widely employed technique for pelvic posterior ring fixation, particularly in developing regions. However, this approach presents technical challenges, leading to a high malposition rate. We introduced a new method for ISS insertion without additional equipment or software and suggested whether it could reduce the malposition rate and operating time. METHODS: This is a retrospective cohort study. The study included all patients who underwent percutaneous ISS fixation between January 2020 and December 2022. Patients treated with open reduction or other types of implants were excluded. The patients were divided into 2 groups based on the screw insertion method: Group A utilized the traditional dual-plane adjustment method, while Group B received the newly introduced method. In all cases, conventional C-arm fluoroscopy was the sole guidance during the surgical procedure. Malposition rate, radiation exposure, and operating time were compared between groups. Post-operative CT scans were used to assess screw accuracy using the Smith grading method. The Student's t-test or the Mann-Whitney U test was chosen for comparing the quantitative variables based on the normality test results. The Chi-squared test was utilized for comparing qualitative variables. RESULTS: A total of 72 patients with pelvic posterior ring disruption treated with percutaneous ISS under conventional fluoroscopy guidance were included in this study. Among them, 32 patients were in Group A and 40 patients were in Group B. In Group B, the average operation duration per screw was 33 min with 29 fluoroscopy applications, which was significantly lower than that in Group A (44 min, p < 0.001, 38 times, p < 0.001, respectively). Furthermore, the post-operative CT scan revealed that only 10.7% (6/56) of screws in Group B were inappropriately positioned according to the Smith criteria. CONCLUSION: The novel method introduced in this study demonstrated a reduction in both malposition rates and operating time compared to the traditional dual-plane adjustment method. Precise pre-operative CT planning in conjunction with conventional fluoroscopy could establish this method as a widely applicable technique for percutaneous ISS fixation.

A novel biplanar positioning technique to guide iliosacral screw insertion: a retrospective study.

PURPOSE: To evaluate the safety and benefits of the biplanar position technique on operative time, radiation exposure, and screw placement accuracy. METHODS: In this study, we retrospectively evaluated the records of 64 patients with pelvic fractures (Tile B and C) between October 2020 and September 2021. According to the surgical methods selected by the patients, the patients were divided into a biplanar positioning technique group (biplanar group), a Ti-robot navigation group (Ti-robot group), and a traditional fluoroscopy-guided technique group (traditional group). Length of operation, blood loss, intra-operative radiation exposure fracture reduction, and the quality of screw positioning were compared among the three groups. RESULTS: One hundred three screws were implanted in 64 patients (biplanar group 22, Ti-robot group 21, traditional group 21). The average operation time was significantly less in the biplanar group (26.32 ± 6.32 min) than in the traditional group (79.24 ± 11.31 min), but significantly more than in the Ti-robot group (15.81 ± 3.9 min). The radiation exposure was similar in the biplanar group (740.53 ± 185.91 cGy/cm2) and Ti-robot group (678.44 ± 127.16 cGy/cm2), both of which were significantly more than in the traditional group (2034.58 ± 494.54 cGy/cm2). The intra-operative blooding loss was similar in the biplanar group (12.76 ± 3.77 mL) and the Ti-robot group (11.92 ± 4.67 mL), both of which were significantly less than in the traditional group (29.7 ± 8.01 mL). The Screw perforation was slightly lower in the biplanar group (94.1%) than in the Ti-robot group (97.2%) but was significantly higher than in the traditional group (75.7%). CONCLUSIONS: The biplanar positioning technique is as accurate and safe as computer-navigated systems for percutaneous iliosacral screw insertion, associated with shorter surgical time, lower intra-operative radiation exposure, and more accuracy compared to traditional fluoroscopy.

Beyond type III Paprosky acetabular defects: are partial pelvic replacements with iliosacral fixation successful?

PURPOSE: Supra-acetabular bone loss close beyond the sciatic notch is one of the most challenging defect types for stable anatomical reconstruction in revision arthroplasty. Using reconstruction strategies from tumour orthopaedic surgery, we adapted tricortical trans-iliosacral fixation options for custom-made implants in revision arthroplasty. The aim of the present study was to present the clinical and radiological results of this extraordinary pelvic defect reconstruction. METHODS: Between 2016 and 2021, 10 patients with a custom-made pelvic construct using tricortical iliosacral fixation (see Fig. 1) were included in the study. Follow-up was 34 (SD 10; range 15-49) months. Postoperatively CT scans evaluating the implant position were performed. Functional outcome and the clinical results were recorded. RESULTS: Implantation was possible as planned in all cases in 236 (SD 64: range 170-378) min. Correct centre of rotation (COR) reconstruction was possible in nine cases. One sacrum screw crossed a neuroforamen in one case without clinical symptoms. During the follow-up period, four further operations were required in two patients. There were no individual implant revisions or aseptic loosening recorded. The Harris Hip Score increased significantly from 27 Pts. to 67 Pts. with a mean improvement of 37 (p < 0.005). EQ-5D developed from 0.562 to 0.725 (p = 0.038) as a clear improvement in quality of life. CONCLUSION: Custom-made partial pelvis replacement with iliosacral fixation offers a safe solution in "beyond Paprosky type III defects" for hip revision arthroplasty. Due to meticulous planning, precise implantation with good clinical outcome can be achieved. Furthermore, the functional outcome and patient satisfaction increased significantly showing promising early results with a relatively low complication rate.

What are the optimal targeting visualizations for performing surgical navigation of iliosacral screws? A user study.

INTRODUCTION: Complex orthopaedic procedures, such as iliosacral screw (ISS) fixations, can take advantage of surgical navigation technology to achieve accurate results. Although the impact of surgical navigation on outcomes has been studied, no studies to date have quantified how the design of the targeting display used for navigation affects ISS targeting performance. However, it is known in other contexts that how task information is displayed can have significant effects on both accuracy and time required to perform motor tasks, and that this can be different among users with different experience levels. This study aimed to investigate which visualization techniques helped experienced surgeons and inexperienced users most efficiently and accurately align a surgical tool to a target axis. METHODS: We recruited 21 participants and conducted a user study to investigate five proposed 2D visualizations (bullseye, rotated bullseye, target-fixed, tool-fixed in translation, and tool-fixed in translation and rotation) with varying representations of the ISS targets and tool, and one 3D visualization. We measured the targeting accuracy achieved by each participant, as well as the time required to perform the task using each of the visualizations. RESULTS: We found that all 2D visualizations had equivalent translational and rotational errors, with mean translational errors below 0.9 mm and rotational errors below 1.1[Formula: see text]. The 3D visualization had statistically greater mean translational and rotational errors (4.29 mm and 5.47[Formula: see text], p < 0.001) across all users. We also found that the 2D bullseye view allowed users to complete the simulated task most efficiently (mean 30.2 s; 95% CI 26.4-35.7 s), even when combined with other visualizations. CONCLUSIONS: Our results show that 2D bullseye views helped both experienced orthopaedic trauma surgeons and inexperienced users target iliosacral screws accurately and efficiently. These findings could inform the design of visualizations for use in a surgical navigation system for screw insertions for both training and surgical practice.

Long-term outcomes of ilio-sacral screws in minimally invasive bipolar fusionless technique for neuromuscular scoliosis: a retrospective study in 167 patients.

INTRODUCTION: Pelvic fixation in patients with neuromuscular scoliosis is difficult, due to their fragile general condition and poor bone quality. Many techniques have been described, associated with high rates of mechanical complications. The objective of this work was to evaluate the mechanical complications and long-term radiological results of ilio-sacral screw pelvic fixation. MATERIALS AND METHODS: 167 consecutive patients with neuromuscular scoliosis who underwent minimally invasive bipolar fixation with ilio-sacral screw pelvic fixation were retrospectively reviewed. The instrumentation consisted in a bilateral sliding rods construct extended from T1 to the sacrum, anchored proximally by double-hook claws and distally by ilio-sacral screws through a minimally invasive approach. Mechanical complications and radiographic measurements (angle of the major coronal curve, pelvic obliquity, lumbar lordosis) were evaluated preoperatively, postoperatively, and at the last follow-up. RESULTS: Mean operative age was 12 ± 3 years, and follow-up 6.4 years (3.0-10.4 years). Pelvic obliquity decreased from 20° preoperatively to 5° (77% correction) at last follow-up, Angle of the major coronal curve from 75° to 36° (52% correction), and lumbar lordosis from 28° to 38°. 16 mechanical complications in nine patients occurred: screw prominence (n = 1), connector failure (n = 4), screw malposition (n = 11). Unplanned surgery was required in seven cases, two were managed during rod lengthening, seven did not require treatment. CONCLUSION: In this series of neuromuscular patients operated by ilio-sacral screws as pelvic fixation, the results were stable with a mean follow-up of more than 6 years and the complication rate was reduced comparatively to the literature.

Efficacy comparison between iliosacral screw fixation of the posterior pelvic ring fracture with the assistance of modified percutaneous three-dimensional printing guide template and conventional fluoroscopy. / æ”¹è‰¯ç»çš®ä¸‰ç»´æ‰“å°å¯¼æ¿ä¸Žä¼ ç»Ÿé€è§†è¾ åŠ©éª¶é«‚èžºé’‰å›ºå®šéª¨ç›†åŽçŽ¯éª¨æŠ˜çš„ç–—æ•ˆæ¯”è¾ƒ.

OBJECTIVES: The effect of three-dimensional (3D) printed bone-attached guide plate assisted cannulated screw fixation of pelvic fracture is reliable, but extensive soft tissue dissection is still required when installing the guide plate. This study aims to compare the efficacy of posterior pelvic ring fracture fixation with iliosacral screw insertion between the assistance of modified percutaneous patient specific 3D printed guide template and conventional fluoroscopy. METHODS: From May, 2019 and September 2021, 28 patients sustained posterior pelvic ring fractures were randomized into 2 groups: A guide template group, in which the iliosacral screw was inserted for fixation of the posterior pelvic ring fracture with the assistance of modified percutaneous patient specific 3D printed guide template, and a fluoroscopy group, in which the iliosacral screw was inserted under the guidance of conventional fluoroscopy. The operation time, fluoroscopic frequency, intraoperative blood loss, and incision length were recorded for each screw insertion. Fracture reduction was evaluated according to the Matta criteria. The screw position was evaluated according to the modified Gras classification, and the functional outcome was evaluated according to Majeed score. The parameters of both groups were compared, and statistical analysis was performed. RESULTS: All the 28 patients were followed up for 12-24 months. Of them, 15 iliosacral screws were inserted in 14 patients in the guide template group, and 14 iliosacral screws were inserted in 14 patients in the fluoroscopy group. The operation time, fluoroscopic frequency, screw deviation, incision length, and blood loss in the guide template group were 20-30(25.8±2.8) min, 9-15(12.2±1.9), 2-4(2.6±0.7) mm, 4-5(4.6±0.5) cm, and 5-10 (7.8±1.7) mL, respectively, whereas those in the fluoroscopy group were 30-60(48.1±7.5) min, 40-96(64.7±16.3), 3-6(4.2±0.9) mm, 0.8-1.2(1.0±0.1) cm, and 2-5(3.1±1.3) mL, respectively, and there were statistical significance (all P<0.001). Fracture reduction was evaluated according to the Matta criteria, and all the patients reached excellence and good (P=0.584) in the 2 groups. According to modified Gras classification, there were 12 Grade I screws, 3 Grade II screws, and 0 Grade III screws in the guide template group, and 10 Grade I screws, 3 Grade II screws, and 1 Grade III screw in the fluoroscopy group, with no statistical significance (P=0.334). The functional outcome was evaluated according to Majeed score at the last follow-up, without significant difference between the guide template group and the fluoroscopy group (P=0.908). CONCLUSIONS: Compared with the conventional fluoroscopy, it would cost less operation time, less fluoroscopic frequency and increase more accurate screw insertion to fixate the posterior pelvic ring fracture with the assistance of modified percutaneous patient specific 3D printed guide template.

Nonoperative management of minimally displaced lateral compression type 1 (LC1) injuries with comminuted rami fractures is associated with late displacement.

PURPOSE: Rami comminution has been found to be predictive of lateral compression type 1 (LC1) injury instability on examination under anesthesia (EUA) and lateral stress radiographs (LSR). The purpose of this study was to evaluate how rami comminution and subsequent operative vs. nonoperative management impact the late displacement of these injuries. METHODS: Retrospective review of a prospectively collected LC1 database was performed to identify all patients with minimally displaced LC1 injuries (< 1 cm) and follow-up radiographs over a four-year period (n = 125). Groups were separated based on the presence of rami comminution and subsequent management, including rami comminution/operative (n = 49), rami comminution/nonoperative (n = 54), and no comminution/nonoperative (control group, n = 22). The primary outcome was late fracture displacement, analyzed as both a continuous variable and as late displacement ≥ 5 mm. RESULTS: As a continuous variable, late fracture displacement was lower in the comminuted rami/operative group as compared to the comminuted rami/nonoperative group (PD: -3.0 mm, CI: -4.8 to -1.6 mm, p = 0.0002) and statistically non-different from control. Late displacement ≥ 5 mm was significantly more prevalent in the comminuted rami/nonoperative group than in the comminuted rami/operative and no comminution/nonoperative groups (control)(PD: -33.9%, CI: -49.0% to -16.1%, p = 0.0002 and PD: -30.0%, CI: -48.2% to -6.5%, p = 0.02, respectively). CONCLUSION: Late fracture displacement was greatest in the group with rami comminution/nonoperative management. Rami comminution, which has been previously associated with dynamic displacement on EUA and LSR, is also associated with a higher incidence of late displacement when managed nonoperatively. LEVEL OF EVIDENCE: Level III, prognostic retrospective cohort study.

Percutaneous pelvic fixation model: an affordable and realistic simulator for pelvic trauma training.

PURPOSE: To describe the construction and use of a percutaneous pelvic fixation model, evaluate its translational validity among fellowship-trained orthopedic trauma surgeons, and investigate the importance of specific criteria for effective competency-based assessment of pelvic fixation techniques. METHODS: Five orthopedic trauma surgeons were asked to place percutaneous wires on a pelvic fixation model, including anterior column (antegrade/retrograde), posterior column (antegrade/retrograde), supra-acetabular, transsacral, and iliosacral. Evaluation criteria included successful wire placement, redirections, cortical breaches, procedure duration, radiation exposure, and quality of fluoroscopic views. Following completion, participants were provided a survey to rate the model. RESULTS: There were no differences between approaches on successful screw placement, wire redirections, or fluoroscopic quality. Antegrade approaches to the anterior and posterior columns took longer (p = 0.008) and used more radiation (p = 0.02). There was also a trend toward more cortical breaches with the antegrade anterior column approach (p = 0.07). Median ratings among surgeons were 4 out of 5 for their overall impression and its accuracy in tactile response, positioning constraints, and fluoroscopic projections. Learning parameters considered most important to the progression of trainees (most to least important) were successful screw placement, corridor breaches, wire redirections, quality of fluoroscopic views, radiation exposure, and procedure duration. CONCLUSION: In being affordable, accessible, and realistic, this percutaneous pelvic fixation model represents an opportunity to advance orthopedic surgery education globally. Future research is needed to validate the findings of this pilot study and to expand upon how trainees should be evaluated within simulations and the operating room to optimize skill progression.

Higher pelvic incidence values are a risk factor for trans-iliac trans-sacral screw malposition in sacroiliac complex fracture treatment.

BACKGROUND: Percutaneous iliosacral (IS) screw fixation and trans-iliac trans-sacral (TITS) screw fixation are clinically effective treatments of posterior pelvic sacroiliac fractures. In order to accurately assess the sacrum position relative to the pelvis, pelvic incidence (PI) is a commonly utilized radiographic parameter in sagittal view. This study aimed to investigate and compare the surgical outcomes and radiographic parameters of IS or TITS screw fixations for the treatment of posterior sacroiliac complex fractures with different PI values. MATERIALS AND METHODS: The data on patients with posterior pelvic sacroiliac fractures who underwent percutaneous IS or TITS screw fixations, or both, at a single level I trauma center between January 2017 and June 2020 were reviewed. We documented the patient characteristics and fracture types, reviewed surgical records, and measured the radiographic parameters via plain films and multi-planar computed tomography (mpCT) images. Radiographic variations in PI, sacral slope, pelvic tilt, sacral dysmorphism, pelvic ring reduction quality, screw deviation angles, screw malposition grading, and iatrogenic complications were documented and analyzed. RESULTS: A total of 85 patients were included, and 65 IS and 70 TITS screws were accounted for. Patients were divided into two groups according to screw fixation method and further divided into four sub-groups based on baseline PI values. The PI cutoff values were 49.85° and 48.05° in the IS and TITS screw groups, respectively, according to receiver operating characteristic analysis and Youden's J statistic. Smaller PI values were significantly correlated with sacral dysmorphism (p = 0.027 and 0.003 in the IS and TITS screw groups, respectively). Patients with larger PI values were at a significantly increased risk of screw malposition in the TITS screw group (p = 0.049), with no association in the IS screw group. Logistic regression confirmed that a larger PI value was a significant risk factor for screw malposition in the TITS screw group (p = 0.010). The post-operative outcomes improved from poor/fair (at 6 months) to good/average (at 12 months) based on the Postel Merle d'Aubigné and Majeed scores, with no significant differences between subgroups. CONCLUSIONS: Both percutaneous IS and TITS screw fixations are safe and effective treatments for posterior pelvic sacroiliac fractures. Due to the higher risk of screw malposition in patients with larger PI values, it is crucial to identify potential patients at risk when performing TITS screw fixation surgery. LEVEL OF EVIDENCE: Level III.

Percutaneous posterior transiliac plate versus iliosacral screw fixation for posterior fixation of Tile C-type pelvic fractures: a retrospective comparative study.

BACKGROUND: This study aimed to compare the clinical outcomes and complications between two minimally invasive surgical techniques: percutaneous transiliac plate fixation and iliosacral (IS) screw fixation for the treatment of Tile C-type pelvic bone fractures. METHODS: We retrospectively reviewed the data of 77 consecutive patients with Tile C pelvic ring injuries who underwent either percutaneous transiliac plate fixation or IS screw fixation in a single academic center between November 2007 and January 2018. We recorded patients' demographics, surgery-related data, and postoperative surgical outcomes and compared the incidence of complications and revision surgery rates between the two groups. RESULTS: Overall, 14 patients were included in the plate group, while 63 were included in the IS screw fixation group. No significant differences were observed in the patients' demographics between the two groups except for a longer interval from injury to surgery (13.5 days vs. 5.4 days, P = 0.001). Both groups acquired fracture union in all cases. There was one case of infection requiring surgical debridement in the plating group. Notably, nerve injury (n = 3) and implant loosening (n = 5) occurred in the IS screw group, but the difference was not significant. CONCLUSIONS: Both percutaneous posterior transiliac plating and IS screw fixation in patients with Tile C-type pelvic bone fractures showed good results. We recommend IS screw fixation as the primary treatment and propose posterior plating as treatment for sacral dysmorphism and bilateral sacral alar fractures in patients with spinopelvic dissociation. LEVEL OF EVIDENCE: III.

Preoperative CT simulation of iliosacral screws for treating unstable posterior pelvic ring injury.

BACKGROUND: The percutaneous iliosacral screw is a common procedure for treating pelvic posterior ring instability. Traditional X-ray fluoroscopy screw placement has the advantages of decreased bleeding and trauma, but it also has some drawbacks, such as increased radiation exposure and screw dislocation. The purpose of this study was to establish a safe, effective, and quick approach for putting iliosacral screws for the treatment of unstable posterior pelvic ring damage utilizing simulated screws based on preoperative computed tomography (CT) planning. METHODS: From February 2019 to June 2020, we retrospectively assessed 41 patients with posterior pelvic ring instability who were treated with percutaneous iliosacral screws in our institution, and randomly separated them into two groups: conventional surgery (n = 20) and preoperative planning (n = 21). Pelvic radiographs (anteroposterior, inlet, outlet), as well as normal CT scans of the pelvis, were all taken postoperatively to confirm the screw position. After that, the screw insertion time, the radiation exposure time, and the screw misplacement rate (as assessed by postoperative CT) were all examined. Screw position grading was evaluated by Smith grading. RESULTS: In the conventional surgery group, 26 screws were inserted in 20 patients, with each screw insertion taking 23.15 ± 4.19 min and 1.02 ± 0.17 min to expose to radiation. Eight of the 26 screws were misplaced (30.8%). In the preoperative planning group, 24 screws were inserted in 21 patients, with each screw taking 19.57 ± 4.05 min to implant and 0.67 ± 0.09 min to expose to radiation. One of 24 screws was misplaced (4.2%). Screw insertion time, radiation exposure time, and screw dislocation rate were all significantly reduced when preoperative planning aided iliosacral screw placement (P < 0.05). CONCLUSIONS: Preoperative CT simulation of iliosacral screws for placement planning, screw trajectory, and intraoperative screw placement is a safe way for reducing surgical time, radiation exposure, and ensuring accurate screw placement.

Modified percutaneous iliosacral screw and anterior internal fixator technique for treating unstable pelvic fractures: a retrospective study.

BACKGROUND: The commonly used technique for treating unstable pelvic fractures with sacroiliac screws and anterior internal fixator (INFIX) is prone to complications, such as injury to the pelvic vasculature and nerves, life-threatening bleeding, lateral femoral cutaneous neuritis, and wound infection. This study investigated the clinical effects of using a modified percutaneous iliosacral screw and INFIX technique for treating unstable pelvic fractures. METHODS: A retrospective analysis of minimally invasive internal fixation using modified incision of an anterior-ring INFIX application combined with modified percutaneous iliosacral screw placement was performed for 22 cases of unstable pelvic fractures from January 2017 to December 2018. Based on the Tile classification, there were 4 type B1, 7 type B2, 5 type B3 and 6 type C1 injuries. Preoperatively, the length and orientation of the internal fixation were computer-simulated and measured. On postoperative day 3, pelvic radiographs and three-dimensional computed tomograms were used to assess fracture reduction and fixation. All patients were regularly followed up at 4 weeks, 12 weeks, 6 months, 12 months, 24 months and annually thereafter. Fracture healing, complications, visual analogue scale (VAS) scores, the quality of fracture repositioning and Majeed score were assessed during follow-up. RESULTS: All patients were followed up for a mean of 25.23 ± 1.48 months. All fractures healed without loss of reduction and no patient showed evidence of delayed union or nonunion. Two years postoperatively, the mean VAS score was 0.32 ± 0.09 and the mean Majeed score was 94.32 ± 1.86. CONCLUSION: The modified percutaneous iliosacral screw technique increases the anterior tilt of the sacroiliac screw by shifting the entry point posteriorly to increase the safety of the screw placement. Downward modification of the INFIX incision reduces the risk of lateral femoral cutaneous nerve injury. This technique is safe, effective and well tolerated by patients.

Prognostic role of affected side of the sacroiliac joint in pain recurrence after total hip arthroplasty with prior manual correction of iliosacral dislocation: prospective randomized clinical study.

INTRODUCTION: Degenerative changes in the hip joint as indications for operative treatment are observed in more than a third of the population over the age 50. In most cases, the development of a degenerative process in the hip joint is accompanied by changes in the sacroiliac joint. To improve the quality of life, relieve pain, and improve the clinical outcomes of rehabilitation after total hip arthroplasty (THA), an integrated approach should be chosen. MATERIALS AND METHODS: Eighty-four patients were enrolled in a prospective randomized study, between 2017 and 2020. The patients were randomly (with the use of computer) divided into two groups (42 to group I, 42 to group II). The first group of patients underwent surgery using a new technique that included intra-operative manual correction of iliosacral dislocation of the sacroiliac joint, whilst the second group of patients underwent THA according to the standard protocol. All groups of patients underwent THA. Clinical treatment outcomes were assessed with the use of the Visual Analogue Scale (VAS) and the Harris Hip Score (HHS). Kaplan-Meier estimator was constructed to determine the differences in the probability of recurrence of pain syndrome depending on the side of the dislocated sacroiliac joint. NCT04673747 (ClinicalTrials.gov identifier). RESULTS: There was a significant pain relief and an improvement in the quality of life of patients who underwent intra-operative manual correction of sacroiliac joint dislocation compared with the group of patients who underwent standard THA. CONCLUSION: The use of intra-operative manual correction of sacroiliac joint dislocation can lead to a pronounced improvement in the quality of life of patients, pain decrease, and an improvement in rehabilitation of patients after performing THA. According to the analysis of statistical data, a potential risk factor for recurrence of pain, is the presence of dislocation on the contralateral side from the operated joint.

Iliosacral Bone Tumor Resection Using Cannulated Screw-Guided Gigli Saw - A Novel Technique.

BACKGROUND: Adequate margins are technically difficult to achieve for malignant tumors involving the sacroiliac joint due to limited accessibility and viewing window. In order to address the technical difficulties faced in iliosacral tumor resection, we proposed a technique for precise osteotomy, which involved the use of canulated screws and Gigli saw (CSGS) that facilitated directional control, anteroposterior linkage of resection points and adequate surgical margins. The purpose of the current study was to evaluate whether CSGS technique facilitated sagittal osteotomy at sacral side, and were adequate surgical margins achieved? Also functional and oncological outcomes was determined along with the noteworthy complications. METHODS: From April 2018 to November 2019, we retrospectively reviewed 15 patients who underwent resections for primary tumors of pelvis or sacrum necessitating iliosacral joint removal using the proposed CSGS technique. Chondrosarcoma was the most common diagnosis. The osteotomy site within sacrum was at ipsilateral ventral sacral foramina in 8 cases, midline of sacrum in 5 cases, and contralateral ventral sacral foramina and sacral ala with 1 case each. The average intraoperative blood loss was 3640 mL (range, 1200 and 6000 mL) with a mean operation duration of 7.4 hours (range, 5 to 12 hours). The mean follow-up was 23.0 months (range, 18 and 39 months) for alive patients. RESULTS: Surgical margins were wide in 12 patients (80%), wide-contaminated in 1 patient (6.7%), and marginal in 2 patients (13.3%). R0 resection was achieved in 12 (80%) patients and R1 resection in 3 patients. There were three local recurrences (20%) occurred at a mean time of 11 months postoperatively. No local recurrence was observed at sacral osteotomy. The overall one-year and three-year survival rate was 86.7% and 72.7% respectively.Complications occurred in three patients. CONCLUSIONS: The current study demonstrated that CSGS technique for tumor resection within the sacrum and pelvis was feasible and can achieve ideal resection accuracies. The use of CSGS was associated with high likelihood of negative margin resections in the current series. Intraoperative use of CSGS appeared to be technically straightforward and allowed achievement of planned surgical margins. It is worthwhile to consider the use of CSGS technique in resection of pelvic tumors with sacral invasion and iliosacral tumors, however further follow-up at mid to long-term is warranted to observe local recurrence rate.

Applicable safety analysis and biomechanical study of iliosacral triangular osteosynthesis.

BACKGROUND: The aim of this study was to investigate the applicable safety and biomechanical stability of iliosacral triangular osteosynthesis (ITO) through 3D modeling and finite element (FE) analysis. METHODS: Pelvic CT imaging data from 100 cases were imported into Mimics software for the construction of 3D pelvic models. The S2-alar-iliac (S2AI) screws and S2 sacroiliac screws were placed in the S2 segment with optimal distribution and their compatibility rate on the S2 safe channel was observed and analyzed. In the FE model, the posterior pelvic ring was fixed with two transsacral screws (TTS), triangular osteosynthesis (TO) and ITO, respectively. Four different loading methods were implemented in sequence to simulate the force in standing, flexion, right bending, and left twisting, respectively. The relative displacement and change in relative displacement of the three fixing methods were recorded and analyzed. RESULTS: The theoretical compatibility rate of S2AI screw and S2 sacroiliac screw in S2 segment was 94%, of which 100% were in males and 88% in females. In the FE model, in terms of overall relative displacement, TTS group showed the smallest relative displacement, the ITO group showed the second smallest, and the TO group the largest relative displacement. The change in relative displacement of the TTS group displayed the smaller fluctuations in motion. The change in relative displacement of the TO group under right bending and left twisting displayed larger fluctuations, while the ITO group under flexion displayed larger fluctuations. CONCLUSIONS: The simultaneous placement of S2AI screw and S2 sacroiliac screw in the S2 segment is theoretically safe. Although the biomechanical stability of ITO is slightly lower than TTS, it is better than TO, and can be used as a new method for the treatment of posterior pelvic ring injuries.

Posterior pelvic ring bone density with implications for percutaneous screw fixation.

BACKGROUND: Although the second (S2) and third (S3) sacral segments have been established as potential osseous fixation pathways for screw fixation, the S2 body has been demonstrated to have inferior bone density when compared to the body of the first (S1) sacral segment. Caution regarding the use of iliosacral screws at this level has been advised as a result. As transiliac-transsacral screws traverse the lateral cortices of the posterior pelvis, they may be relying on bone with superior density for purchase, which could obviate this concern. The objective of this study was to compare the bone density of the posterior ilium and sacroiliac joint to that of the sacral body at the first (S1), second (S2), and third (S3) sacral levels. MATERIALS AND METHODS: A retrospective case series was performed, reviewing the CT scans of 100 patients without prior pelvic trauma. Each CT was confirmed to have available osseous fixation pathways at the first (S1), second (S2), and third (S3) sacral segments. The bone density of the posterior ilium/sacroiliac joint (PISJ) and sacral body (SB) was measured using the embedded standardized Hounsfield units (HU) tool at each sacral level. RESULTS: The average S2 PISJ bone density (320.1) was significantly higher than the S1 (286.5) and S3 (278.9) PISJ (p < 0.0001) and S1 and S3 PISJ was not statistically different. The S1 sacral body bone density (231.1) was significantly higher than the S2 (182.1) and S3 (126.8) bone density (p < 0.0001). The PISJ bone density is greater than the sacral body at every sacral level (p < 0.0001). CONCLUSION: The S2 PISJ bone density is significantly greater than S1. The S1, S2, and S3 PISJ bone density is greater than the sacral body at all sacral levels, and the S1 body has higher bone density than the S2 and S3 bodies. These differences in bone density may have implications for the stability of posterior pelvic ring fixation constructs with regard to screw purchase. LEVEL OF EVIDENCE: Level III-Case cohort series.

The iliosacral joint in lizards: an osteological and histological analysis.

The development of the iliosacral joint (ISJ) in tetrapods represented a crucial step in the evolution of terrestrial locomotion. This structure is responsible for transferring forces between the vertebral column and appendicular skeleton, thus supporting the bodyweight on land. However, most research dealing with the water-to-land transition and biomechanical studies in general has focused exclusively on the articulation between the pelvic girdle and femur. Our knowledge about the contact between the pelvic girdle and vertebral column (i.e. the ISJ) at a tissue level is restricted so far to human anatomy, with little to no information available on other tetrapods. This lack of data limits our understanding of the development and evolution of such a key structure, and thus on the pattern and processes of the evolution of terrestrial locomotion. Therefore, we investigated the macro- and microanatomy of the ISJ in limb-bearing squamates that, similar to most non-mammalian, non-avian tetrapods, possess only two sacral ribs articulating with the posterior process of the ilium. Using a combination of osteology, micro-computed tomography and histology, we collected data on the ISJ apparatus of numerous specimens, sampling different taxa and different ontogenetic stages. Osteologically, we recorded consistent variability in all three processes of the ilium (preacetabular, supracetabular and posterior) and sacral ribs that correlate with posture and locomotion. The presence of a cavity between the ilium and sacral ribs, abundant articular cartilage and fibrocartilage, and a surrounding membrane of dense fibrous connective tissue allowed us to define this contact as a synovial joint. By comparison, the two sacral ribs are connected to each other mostly by dense fibrous tissue, with some cartilage found more distally along the margins of the two ribs, defining this joint as a combination of a syndesmosis and synchondrosis. Considering the intermediary position of the ISJ between the axial and appendicular skeletons, the shape of the articular surfaces of the sacral ribs and ilium, and the characteristics of the muscles associated with this structure, we argue that the mobility of the ISJ is primarily driven by the movements of the hindlimb during locomotion. We hypothesize that limited torsion of the ilium at the ISJ happens when the hip is abducted, and the joint is likely able to absorb the compressional and extensional forces related to the protraction and retraction of the femur. The mix of fibres and cartilage between the two sacral ribs instead serves primarily as a shock absorber, with the potential for limited vertical translation during locomotion.

Part 1: Outcome of Posterior Pelvic Ring Injuries and Associated Prognostic Factors - A Five-Year Retrospective Study of One Hundred and Sixty Five Operated Cases with Closed Reduction and Percutaneous Fixation.

PURPOSES: The aim of this study was to evaluate: 1. the outcome of pelvic ring fractures treated by closed reduction and percutaneous fixation, 2. the prognostic factors associated with a poor quality reduction, 3. the prognostic factors associated with ilio-sacral screws misplacement and 4. the prognostic factors associated with nonunion. METHODS: Data from medical charts for all patients admitted with unstable posterior pelvic ring injuries from 2009 to 2013 were extracted. A total of 165 patients with a mean age of 40 years were included. One hundred and five patients were reviewed at a mean of 32 months of follow-up. The prognostic factors analyzed were clinical and radiological factors. Tile B and Tile C pelvic ring fractures were compared and analyzed separately. Then specific statistical analysis was performed using a logistic regression model to eliminate confusion factors. RESULTS: An excellent or good clinical result was achieved for 94 patients (90%). An excellent or good reduction was achieved for 141 patients (85%). Nonunion rate, smoking patients, bad reductions, age of patients and ISS score were significantly higher in Tile C group. To eliminate confusion factors we used a multivariate analysis logistic regression model. Only unstable vertical bilateral posterior injuries (Tile C2 and C3) were independent prognostic factors for unsatisfactory reduction (p = 0.001; OR = 4.72; CI 95% [2.08-16.72]). Screw misplacement was recorded for 30 patients (16%) and sacral dysmorphia was an associated prognostic factor (p = 0.0001; OR = 15.6; CI95% [3.41-98.11]). Nonunion was recorded for ten patients (6%) and smoking was an associated prognostic factor (p = 0.01, OR = 5.12; CI95% [1.1-24.1]). CONCLUSIONS: Posterior pelvic ring fractures treated by closed reduction and percutaneous fixation are associated with excellent/good clinical results if excellent/good reduction and bone healing are achieved without screw misplacement. Bilateral unstable vertical posterior pelvic ring injuries, and sacral dysmorphia are risk factors for bad quality reduction and screw misplacement respectively.

Results of open reduction internal fixation versus percutaneous iliosacral screw fixation for unstable pelvic ring injuries: retrospective study of 36 patients.

INTRODUCTION: Surgical stabilization of posterior pelvic ring fractures can be achieved by closed reduction and percutaneous fixation (CRPF) or by open reduction and internal fixation (ORIF). The aim of the present study is to compare the clinical results of both methods. MATERIAL AND METHODS: Medical records of 36 patients consecutively operated for unstable pelvic ring injuries were retrospectively reviewed. We compared 22 patients treated with CRPF versus 14 patients stabilized by using ORIF between 2007 and 2017. The Majeed and Pohlemann scores were used to evaluate postoperative functional outcomes. Complications like blood loss, infection rate, Neurological injury, the operative time and the length of hospital stay were analyzed. RESULTS: The median Majeed pelvic score was 87 points for the CRPF technique compared with 69 points for the ORIF technique. The median Pohlemann score, operative time and length of hospitalization were similar between the two groups. The median blood loss for the CRPF technique was 300 ml compared to 500 ml for the ORIF technique. CRPF and ORIF procedure had each one neurological lesion. There was one case of infection in the ORIF group and none in the CRPF group. No measurements except for the blood loss have reached the significance threshold. CONCLUSION: The CRPF technique shows a clear decrease in blood loss. There was no statistically significant difference in the functional results, infection rate, neurological injury, operative time and hospital stay between both techniques.

Bone density of first and second segments of normal and dysmorphic sacra.

BACKGROUND: Iliosacral screw fixation is safe and effective but can be complicated by loss of fixation, particularly in patients with osteopenic bone. Sacral morphology dictates where iliosacral screws may be placed when stabilizing pelvic ring injuries. In dysmorphic sacra, the safe osseous corridor of the upper sacral segment (S1) is smaller and lacks a transsacral corridor, increasing the need for fixation in the second sacral segment (S2). Previous evidence suggests that S2 is less dense than S1. The aim of this cross-sectional study is to further evaluate bone mineral density (BMD) of the S1 and S2 iliosacral osseous pathways through morphology stratification into normal and dysmorphic sacra. MATERIALS AND METHODS: Pelvic computed tomography scans of 50 consecutive trauma patients, aged 18 to 50 years, from a level 1 trauma center were analyzed prospectively. Five radiographic features (upper sacral segment not recessed in the pelvis, mammillary bodies, acute alar slope, residual S1 disk, and misshapen sacral foramen) were used to identify dysmorphic characteristics, and sacra with four or five features were classified as dysmorphic. Hounsfield unit values were used to estimate the regional BMD of S1 and S2. Student's t-test was utilized to compare the mean values at each segment, with statistical significance being set at p < 0.05. No change in clinical management occurred as a result of inclusion in this study. RESULTS: A statistical difference in BMD was appreciated between S1 and S2 in both normal and dysmorphic sacra (p < 0.0001), with 28.4% lower density in S2 than S1. Further, S1 in dysmorphic sacra tended to be 4% less dense than S1 in normal sacra (p = 0.047). No difference in density was appreciated at S2 based on morphology. CONCLUSIONS: Our results would indicate that, based on BMD alone, fixation should be maximized in S1 prior to fixation in S2. In cases where S2 fixation is required, we recommend that transsacral fixation should be strongly considered if possible to bypass the S2 body and achieve fixation in the cortical bone of the ilium and sacrum. LEVEL OF EVIDENCE: Level III.