Biomechanical Analysis of a Modified Triangular Osteosynthesis Technique for Treatment of Spinopelvic Dissociation.

OBJECTIVES: The purpose of this study was to evaluate the biomechanical stability of a modified triangular osteosynthesis construct with S1 pedicle screws compared with other described lumbopelvic fixation constructs in a U-type sacral fracture model. METHODS: U-type sacral fractures were created in validated fourth-generation spinopelvic models. Four different constructs were cyclically loaded with displacement measured in all planes: (1) bilateral L5 pedicle screws with rods attached to iliac bolts, (2) bilateral L5 and S1 pedicle screws with rods attached to iliac bolts, (3) bilateral L5 pedicle screws with rods attached to iliac bolts with a transsacral-transiliac screw, and (4) bilateral L5 and S1 pedicle screws with rods attached to iliac bolts with a transsacral-transiliac screw. RESULTS: The bilateral L5 and S1 pedicle screws with rods attached to iliac bolts with a transsacral-transiliac screw construct had significantly decreased horizontal, vertical, and angular displacement compared with all other constructs. CONCLUSIONS: From a biomechanical perspective, a modified triangular osteosynthesis construct with S1 pedicle screws improves stability in fixation of U-type sacral fractures.

Use of a newly developed minimally invasive bilateral fixed angle locking system in the treatment of pathological pelvic fractures: a case series.

BACKGROUND: Metastatic bone disease (MBD) and its complications have a significant impact on patients' quality of life. Pathological fractures are a particular problem as they affect patient mobility and pose a high risk of non-union. The pelvis is frequently affected by MBD and its fixation is challenging. We present a case series of three pathological sacral fractures treated with a new minimally invasive bilateral fixed angle locking system. CASE PRESENTATION: Case 1 and 2 suffered a pathological transforaminal sacral fracture without adequate trauma in stage 4 carcinomas (gastric cancer and breast cancer). Both were initially treated with non-surgical treatment, which had only a limited effect and led to imminent immobility. Both were operated on with fluoroscopic navigation and underwent transsacral SACRONAIL® stabilisation according to CT morphology (S1 + S2 and S1 respectively). Immediately after the operation, pain decreased and mobilisation improved. Case 3 had a pathological transalar sacral fracture during the 2nd cycle of chemotherapy due to non-Hodgkin's lymphoma. He soon became immobile and could only move in a wheelchair. The operation was performed with CT navigation due to the very small corridors and an implant was inserted in S1 and S2. The patient reported immediate pain relief and his ability to walk improved over the following months. Despite continued chemotherapy, no wound complications occurred. CONCLUSIONS: The cases show the advantages of the minimally invasive bilateral fixed angle locking system SACRONAIL® in the treatment of patients with pathological sacral fractures. It allows immediate full weight bearing and the risk of secondary surgical complications is low. All cases showed an improvement in pain scores and mobility.

Lumbosacral rotation flap: a simple method for covering sacral pressure injuries.

BACKGROUND: Pressure injuries (PIs) are among the most common skin and soft tissue wounds occurring in patients who are bedbound and/or immobile. PI management hinges on their prevention; however, reoccurrence poses a challenge to their management and requires a multidisciplinary approach. Here, the authors describe a lumbosacral rotation flap (LSRF) for the coverage of sacral PIs. METHOD: A single-centre, retrospective analysis of prospectively collected data was carried out. All patients undergoing LSRF for sacral PIs were included. Patients with active systemic sepsis, immune compromise, hepatic or renal dysfunction were excluded. All patients underwent preoperative optimisation and wound cultures to direct antibiotic therapy after surgery. RESULTS: A total of nine patients underwent the procedure (seven male and two female). Mean age was 47.6 years with a mean ulcer size of 92.9 cm2. Bone biopsy indicated the presence of osteomyelitis in three patients. Of the LSRFs, two flaps showed minimal local complications in the form of marginal flap necrosis which was managed conservatively. All flaps healed well with no cases of flap loss or the need for secondary procedures. CONCLUSION: The results of this analysis showed that LSRF can be considered a first line of treatment of sacral PIs. They can be used to cover large defects. Due to their large base and flap size, readvancement in cases of recurrence is also possible.

Sacral U-type Fractures in Patients Older Than 65 years.

INTRODUCTION: The purpose of this study was to determine the degree of disability that geriatric patients with sacral U-type fractures experience. METHODS: Patients older than 65 years presenting from 2013 to 2019 with a U-type sacral fracture were included. Patient demographics, treatment type, preinjury domicile, preinjury use of assistive devices, and neurologic deficits were recorded. Outcomes included mortality, return to preinjury domicile, and use of assistive devices for mobility. RESULTS: Among 46 patients in the treatment period, ground-level fall was the most common mechanism of injury (60.8%). Thirty-four patients (74%) were treated surgically, most commonly with closed percutaneous fixation (n = 27). Thirteen percent of patients died during the admission. At the final follow-up, 14 (45%) had not returned to their prior domicile and 18 (58%) required more supportive assistive devices. Seventy-three percent of patients who presented delayed required a new gait aid, compared with 47% presenting acutely. Between those presenting with low-energy versus high-energy mechanisms, similar rates of need were observed for new assistive devices (50% low and 73% high) and lack of return to preinjury domicile (40% low, 50% high). DISCUSSION: Many geriatric patients were disabled by or died after sustaining a sacral U-type fracture, highlighting the morbidity regardless of high-energy or low-energy trauma.

L5-S1 facet joint pathology in pelvic ring injuries.

BACKGROUND: The authors believe that the L5-S1 facet joint injury in the setting of pelvic fractures is underappreciated by orthopedic traumatologists. The purpose of this study was to draw attention to the L5/S1 facet joint in the setting of pelvic ring injuries. METHODS: This was a retrospective comparative study of all patients greater than or equal to 18 years of age with an acute pelvic ring injury (AO/OTA 62 B to C) presenting to a single level I trauma center. The primary objective was to determine demographic and injury characteristics associated with L5-S1 facet joint injuries in patients with pelvic ring injuries. The secondary objective was to determine the proportion of L5-S1 facet joint injuries that were missed on initial radiographic workup. RESULTS: There were 476 patients included in the analysis, 53 (11.1%) of whom had an L5-S1 facet joint injury. Patients with an L5-S1 injury were more likely to be younger (44.1 vs. 53.2 years, p = 0.001) and experience a high energy mechanism of injury (95.0% vs. 78.0%, p = 0.002). Certain injury patterns were associated with L5-S1 facet joint injuries: any sacral fracture (96.2% vs. 73.8%, p < 0.001), Denis zone 2 fractures (43.4% vs. 20.1%, p < 0.001), Denis zone 3 fractures (34.0% vs. 4.7%, p < 0.001), bilateral displaced sacral fractures (18.9% vs. 3.5%, p < 0.001), and L5 transverse process fractures (64.2% vs. 18.0%, p < 0.001). Only 16.0% of radiology reports identified an L5-S1 injury. CONCLUSIONS: Orthopedic traumatologists should scrutinize imaging for L5-S1 facet joint injuries in the presence of pelvic ring injuries, especially in patients with certain sacral fracture patterns.

Clinical Efficacy of Electroacupuncture at Sacral Four Points Combined with Moxibustion at Abdominal Three Points for Treating Post-Stroke Urinary Incontinence: Observations on Urodynamics, Quality of Life, and Safety.

BACKGROUND: Urinary incontinence is a common complication following a stroke. No specific drugs are available in Western medicine, and surgical treatment is highly traumatic, limiting its clinical application. This study aimed to observe the clinical efficacy of electroacupuncture at the "Sacral Four Points" combined with moxibustion at the "Abdominal Three Points" on post-stroke urinary incontinence, exploring its impact on urodynamics and quality of life. METHODS: Patients with post-stroke urinary incontinence treated at our Hospital from January 2021 to December 2023 were recruited. The study included 117 patients: 57 in the electroacupuncture group and 60 in the combined group. Urodynamic parameters were measured, and scores from the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF) and the Incontinence Quality of Life Questionnaire (I-QOL) were recorded before, and after the first and third courses of treatment. Clinical efficacy and adverse reactions were evaluated post-treatment. RESULTS: The study found no significant differences in clinical characteristics between the groups (p > 0.05), providing a baseline for comparison. Both groups showed substantial decreases in leakage volume after one course of treatment (p < 0.05), with a reduction in the ICIQ-UI SF score (p < 0.05) and an increase in the I-QOL score (p < 0.05). After three courses of treatment, the leakage volume of patients in both groups significantly decreased (p < 0.05), the ICIQ-UI SF score decreased (p < 0.05), and the I-QOL score increased (p < 0.05). The combined group showed a lower leakage volume compared to the electroacupuncture group (p < 0.05), with lower ICIQ-UI SF scores (p = 0.027) and higher I-QOL scores (p = 0.048). Importantly, the total effective rate was significantly higher in the combined group (88.33% vs 64.91%, p = 0.037), demonstrating the safety and efficacy of the treatment. CONCLUSIONS: Electroacupuncture at the "Sacral Four Points" combined with moxibustion at the "Abdominal Three Points" improves the clinical symptoms and enhances the quality of life for patients with post-stroke urinary incontinence, showing superior results compared to electroacupuncture alone.

Robotic Placement of 3 Trans-Sacral TransiIliac Screws Through a Single Corridor for U-Type Sacrum Fracture: A Case Report.

CASE: We present a case of robot-assisted placement of 3 trans-sacral transiliac screws through a single corridor for an unstable U-type sacral fracture in a 95-year-old woman. She had persistent pain and inability to mobilize with physical therapy. At 3-month follow-up, the patient had evidence of interval healing and stable hardware and was able to return to her prior functional baseline. CONCLUSION: We demonstrate successful utilization of robotics to place 3 trans-sacral transiliac screws in a single corridor for fixation of an unstable pelvic ring injury. This technique was used to overcome challenges with visualization and implant placement.

Percutaneous lumbopelvic fixation is effective in the management of unstable transverse sacral fractures.

OBJECTIVES: Historically, fractures causing lumbopelvic dissociation have been managed with open lumbosacral fusion and instrumentation. Our aim was to evaluate outcomes and complications following surgical management of unstable transverse sacral fractures with percutaneous lumbopelvic fixation. METHODS: Design: Retrospective case series. SETTING: Academic Single Center, Level I Trauma Center. Patient Selection Criteria: Patients with lumbopelvic dissociation undergoing surgery. Outcome Measures and Comparisons: Patient demographics, mechanism of injury, ISS, associated injuries, radiographic classification (Roy-Camille), patient-reported outcomes (PROMIS PI, PF, D, and ODI), and complications were collected. RESULTS: 27 patients were enrolled with an average follow-up of 18.7 ± 17.6 months and age of 54.4 ± 25.1 years. All patients underwent lumbar pedicle screw and iliac screw placement. Sacral laminectomy was performed if the patient had a preoperative neurological deficit. Patients were counseled on instrumentation removal at 6-12 months. 67 % of patients sustained a fall, and 33 % were involved in an MVA. 52 % were Roy-Camille Type 2, and 32 % and 20 % were Types 1 and 3, respectively. The mean EBL was 261 ± 400 ml. 37 % required concurrent sacral laminectomy. There were no intraoperative complications and four postoperative complications, including surgical site infection, rod dislodgment, and deep venous thrombosis. 63 % underwent removal of instrumentation after fracture healing. ODI scores significantly improved from 6 weeks post-op (35.5 ± 4.5) to one-year follow-up (18.3 ± 9.6, p = 0.005), two-year follow-up (20.3 ± 10.0, p = 0.03), and final follow-up (16.4 ± 8.8, p = 0.002). Statistically significant improvements were observed in the PROMIS PI, PF, and D domains (p < 0.05). CONCLUSION: Our study demonstrates that lumbopelvic instrumentation leads to successful management of unstable transverse sacral fractures, with improvement in PRO. The combination of percutaneous instrumentation without arthrodesis did not result in any fracture non-union. LEVEL OF EVIDENCE: Level IV.

The optimal introversion angle and length of pedicle screw to avoid L1-S1 vascular damage.

BACKGROUND: posterior pedicle screw fixation is common method, one of the most severe complications is iatrogenic vascular damage, no report investigated association of different introversion angles (INTAs) and length of pedicle screw. The aims were to investigate the optimal introversion angle and length of pedicle screw for improving the safety of the operation, and to analyze the differences of vascular damage types at L1-S1. METHODS: Lumbar CT imaging data from110 patients were analyzed by DICOM software, and all parameters were measured by new Cartesian coordinate system, INTAs (L1-L5:5°,10°,15°,S1: 0°, 5°,10°,15°), DO-AVC (the distance between the origin (O) with anterior vertebral cortex (AVC)), DAVC-PGVs (the distance between AVC and the prevertebral great vessels (PGVs)), DO-PGVs (the distance between the O and PGVs). At different INTAs, DAVC-PGVs were divided into four grades: Grade III: DAVC-PGVs ≤ 3 mm, Grade II: 3 mm < DAVC-PGVs ≤ 5 mm, Grade I: DAVC-PGVs > 5 mm, and N: the not touching PGVs. RESULTS: The optimal INTA was 5° at L1-L3, the left was 5° and the right was 15° at L4, and screw length was less than 50 mm at L1-L4. At L5, the left optimal INTA was 5° and the right was 10°, and screw length was less than 45 mm. The optimal INTA was 15° at S1, and screw length was less than 50 mm. However, screw length was less than 40 mm when the INTA was 0° or 5° at S1. CONCLUSIONS: At L5-S1, the risk of vascular injury is the highest. INTA and length of the pedicle screw in lumbar operation are closely related. 3 mm interval of screw length may be more preferable to reduce vascular damage.

Fluoroscopy guided teardrop technique for open trans-muscular iliac screw placement and open reduction maneuvers during modified triangular spinopelvic fixation for unstable U-shaped sacral and tile C pelvic traumas: technical note.

Unstable traumas of the spinopelvic junction, which include displaced U-shaped sacral fractures (Roy-Camille type 2 and type 3) and Tile C vertical shear pelvic ring disruptions, occur in severe traumas patients following high speed traffic accident or fall from a height. These unstable traumas of the spinopelvic junction jeopardize one's ability to stand and to walk by disrupting the biomechanical arches of the pelvis, and may also cause cauda equina syndrome. Historically, such patients were treated with bed rest and could suffer a life-long burden of orthopedic and neurological disability. Since Schildhauer pioneer work back in 2003, triangular spinopelvic fixation, whether it is performed in a percutaneous fashion or by open reduction and internal fixation, allows to realign bone fragments of the spinopelvic junction and to resume walking within three weeks. Nevertheless, such procedure remains highly technical and it not encountered very often, even for spine surgeons working in high-volume level 1 trauma centers. Hence, this visual technical note aims to provide a few tips to guide less experience surgeons to complete this procedure safely.

Effect of different lumbar-iliac fixation and sacral slope for Tile C1.3 pelvic fractures: a biomechanical study.

BACKGROUND: Lumbar-iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4-L5/L5 unilateral LIF (L4-L5/L5 ULIF), bilateral LIF (BLIF), and L4-L5/L5 triangular osteosynthesis (L4-L5/L5 TOS), still lack biomechanical evaluation. The sacral slope (SS) is key to the vertical shear of the sacrum but has not been investigated for its biomechanical role in lumbar-iliac fixation. The aim of this study is to evaluate the biomechanical effects of different LIF and SS on Tile C1.3 pelvic fracture under two-legged standing load in human cadavers. METHODS: Eight male fresh-frozen human lumbar-pelvic specimens were used in this study. Compressive force of 500 N was applied to the L4 vertebrae in the two-legged standing position of the pelvis. The Tile C1.3 pelvic fracture was prepared, and the posterior pelvic ring was fixed with L5 ULIF, L4-L5 ULIF, L5 TOS, L4-L5 TOS, and L4-L5 BLIF, respectively. Displacement and rotation of the anterior S1 foramen at 30° and 40° sacral slope (SS) were analyzed. RESULTS: The displacement of L4-L5/L5 TOS in the left-right and vertical direction, total displacement, and rotation in lateral bending decreased significantly, which is more pronounced at 40° SS. The difference in stability between L4-L5 and L5 ULIF was not significant. BLIF significantly limited left-right displacement. The ULIF vertical displacement at 40° SS was significantly higher than that at 30° SS. CONCLUSIONS: This study developed an in vitro two-legged standing pelvic model and demonstrated that TOS enhanced pelvic stability in the coronal plane and cephalad-caudal direction, and BLIF enhanced stability in the left-right direction. L4-L5 ULIF did not further improve the immediate stability, whereas TOS is required to increase the vertical stability at greater SS.

Prophylactic dressings to prevent sacral pressure injuries in adult patients admitted to intensive care units: A three-arm feasibility randomized controlled trial.

BACKGROUND: Pressure injuries in intensive care patients are a safety issue. Specialized foam sacral prophylactic dressings prevent pressure injuries with several products available for clinicians to choose from. OBJECTIVES: Assess the feasibility of conducting a multisite trial to test the effectiveness of two dressings versus usual care in preventing sacral pressure injuries in intensive care patients. METHODS: Using a three-arm pilot randomized trial design, adult intensive care unit patients at risk for pressure injuries were randomly allocated to the Mepilex® Sacrum dressing, the Allevyn™ Life Sacrum dressing or the control group. Daily pressure injury data were collected including a de-identified sacral photograph, which the blinded outcome assessor used to determine the study end point: a new sacral pressure injury. Pre-determined feasibility criteria were measured in terms of eligibility, recruitment, retention, intervention fidelity and missing data. RESULTS: From May-September 2021, we screened 602 intensive care unit adult patients for eligibility with 93 % (n = 558) excluded. Forty-four (7 %) were eligible, and all were recruited and randomized (100 %). After receipt of the intervention two participants withdrew from the study. Our final sample of 42 participants were randomly allocated to the Mepilex® (n = 12), Allevyn™ (n = 14) or control (n = 16) group. The interventions were delivered as intended and there were 11 (6 %) cases of missing outcome data. Five participants (12 %) developed a sacral pressure injury, four of whom received a sacral dressing. CONCLUSIONS: A larger trial is feasible with minor refinement to the length of stay eligibility criterion. IMPLICATIONS FOR PRACTICE: Prophylactic sacral dressings are recommended for pressure injury prevention. Determining the feasibility of a larger trial to test the effectiveness of two dressings versus usual care in preventing sacral pressure injuries in intensive care patients can provide evidence to aid clinicians, policy makers and managers make value-based care decisions.

Insertion sites of iliosacral screws on the posterior ilium: Implications for posterior pelvic fixation.

OBJECTIVES: Lateral compression type II pelvic ring injuries can be treated with fixation through open or percutaneous approaches depending on the injury pattern and available osseous fixation pathways. The start site of iliosacral screws to stabilize these injuries should be on the unstable posterior iliac fragment; however, our understanding of start sites for iliosacral screws has not been developed. The purpose of this study is to provide an analysis of iliosacral screw start sites on the posterior ilium to help guide treatment of pelvic ring injuries. METHODS: One-hundred and seventeen consecutive patients at an academic level I trauma center with pelvic ring injuries who underwent surgical treatment with iliosacral screws were included in the final analysis. The start sites of iliosacral screws with confirmed intraosseous placement on a postoperative computed tomography were mapped on the posterior ilium and analyzed according to the sacral segment and type of iliosacral screw. RESULTS: One-hundred and seventeen patients were included in the final analysis. Of the total of 272 iliosacral screw insertion sites analyzed, 145 (53%) were sacroiliac-style screws and 127 (47%) were transsacral screws. The insertion sites for sacroiliac-style screws and transsacral screws at different sacral segment levels can vary but have predictable regions on the posterior ilium relative to reliable osseous landmarks. CONCLUSIONS: Iliosacral screws start sites on the posterior ilium have reliable regions that can be used to plan posterior fixation of pelvic ring injuries.

Clinical Features and Therapeutic Process of Sacral Fatigue Fractures in Adolescents.

BACKGROUND: Sacral fatigue fractures are a rare injury but should be considered as a differential diagnosis for low back and buttock pain in young adults. Collective reports are limited, most of which have focused on long-distance runners. PURPOSE: To investigate the characteristics of sacral fatigue fractures in adolescents. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We analyzed patient background characteristics, physical examination and imaging findings, and treatment courses of those diagnosed with sacral fatigue fractures using magnetic resonance imaging. RESULTS: Among 34 patients with sacral fatigue fractures, 15 and 19 were male and female patients, respectively, with an age range of 11 to 19 years (mean age, 15.0 years). Almost all patients were athletes, and 29 patients performed their sport ≥5 times a week. Long-distance runners were the most commonly affected, comprising 7 patients, and participants in other common sports such as baseball (6 patients), basketball (4 patients), and soccer (3 patients) were also affected. Physical examination revealed tension sign (Lasègue test) on the affected side in 6 patients and tight hamstrings in 24 patients. Imaging findings included 18 patients with right-side involvement, 12 with left-side involvement, and 4 with involvement on both sides. In 11 patients, spina bifida occulta was observed at S1 and 8 patients had a history of lumbar spondylolysis with 4 patients having concurrent sacral fatigue fractures. Physical therapy was performed concurrently with the cessation of exercise, and return to exercise was permitted if the pain had been relieved after 1 month. All patients returned to sports at a median of 48 days (range, 20-226 days) after symptom onset. However, 2 patients experienced recurrence (1 patient on the ipsilateral side and 1 patient on the contralateral side). CONCLUSION: Sacral stress fractures are not limited to long-distance runners in this population and can manifest as lower back pain or buttock pain in athletes participating in a variety of sports. Although the course of treatment was generally good, the possibility of recurrence must always be considered.

Treatment Outcomes of Lower Urinary Tract Symptoms due to Fragility Sacral Fractures: A Review of Eight Patients and Literature.

BACKGROUND: Sacral fractures can cause lower urinary tract symptoms (LUTS) due to damage to the cauda equina. While several studies have reported on sacral fractures due to high-energy trauma, those due to fragility fractures have only been reported in case reports and their clinical differences are not well known. This study aimed to investigate the clinical characteristics of LUTS caused by fragility sacral fractures and propose a novel treatment strategy. METHODS: This study is retrospective, uncontrolled, clinical case series. The inclusion criteria were sole sacral fractures due to low-energy trauma and appearance of LUTS after injury. Patients with additional spinal fractures or combined abdominal or pelvic organ injuries that could cause LUTS were excluded. Improvement in LUTS, period from onset to improvement, and imaging findings were recorded. RESULTS: Eight patients met the inclusion criteria (4 surgical and 4 conservative treatment cases). Six patients showed improvement in LUTS. In surgical cases, the mean period from onset of LUTS to surgery and from onset of LUTS to improvement was 14.5 and 21.5 days, respectively. Intraoperative rupture or laceration of the dural sac was not observed. In 2 conservatively improved cases, the period from onset to improvement of LUTS was 14 and 17 days. CONCLUSIONS: LUTS can improve even with conservative treatment and should be utilized as the primary choice. LUTS caused by severe sacral canal deformity and stenosis can be reversible, and the decision to perform surgical treatment is still timely if LUTS do not improve with conservative treatment for several weeks.

The influence of pelvic tilt on sacral insufficiency fracture occurrence: Insights into the prevalence of high pelvic tilt among patients affected.

INTRODUCTION: Fragility fractures without significant trauma of the pelvic ring in older patients have an increasing incidence due to demographic change. Influencing factors other than osteoporotic bone quality that lead to an insufficiency fracture are not yet known. However, it is suspected that the pelvic tilt (PT) has an effect on the development of such an insufficiency fracture. This study explores the influence of the PTs in patients with insufficiency fractures of the posterior pelvic ring. MATERIALS AND METHODS: A total of 49 geriatric patients with fragility fractures of the pelvic ring were treated at a university hospital level-1 trauma center during a period between February and December 2023, and their fractures were classified according to the FFP classification of Rommens and Hofmann. Complete sets of computer tomography (CT) and radiological images were available to determine the PT angle of the patients. RESULTS: 34 FFP type 2 and 15 FFP type 3 classified patients were included in the study. Significant difference was seen in the pelvic tilt (PT) angle between the patient group with insufficiency fractures (n= 49; mean age: 78.02 ± 11.80) and the control group with lumbago patients (n= 53; mean age: 69.23 ± 11.23). The PT was significantly higher in the patients with insufficiency fractures (25.74° ± 4.76; p⁎⁎⁎⁎ ≤ 0.0001). CONCLUSIONS: The study demonstrates a significant extension of the PT angle of individuals with insufficiency fractures when compared to those with lumbago. The result suggests a potential association between pelvic tilt and fracture susceptibility. TRIAL REGISTRATION: A retrospective study about the influence of sagittal balance of the spine on insufficiency fractures of the posterior pelvic ring measured by the "pelvic tilt angle", DRKS00032120. Registered 20th June 2023 - Prospectively registered. Trial registration number DRKS00032120.

Comparison of the zonal distribution of calcium salt density and fat marrow in bone-healthy and osteoporotic sacra: an image data analysis using quantitative computed tomography and magnetic resonance imaging.

PURPOSE: Pathogenesis of sacral fragility fractures is not fully understood. This study investigates zonal distribution of calcium salt and fat marrow in intact bone-healthy and osteoporotic pelvis. In addition, in unilateral sacral fractures, the fracture side was compared with the intact side. METHODS: CT and MRI images of 37 pelves were analyzed. Zonal calcium salt distribution by Hounsfield units (HU) was recorded for each CT dataset. Fat marrow content was measured in MRI mDixon-Quant sequence. The cohort was divided: intact pelves with (PEO, HU < 100, n = 8) and without osteoporosis (PE, HU ≥ 100, n = 14) based on the mean HU value in LWK5. A third group consisted of patients with osteoporosis and unilateral fractures (PEOFx, n = 10). CONCLUSION: The results suggest that in PEO sacral alae experience disproportionate skeletal rarefaction. This concerns the sacral ala at the S1 level (- 25 ± 55), whereby the calcium salt content is so low that it corresponds to the S3 level of healthy bone (- 20 ± 21 HU). This explains the occurrence of transalar fractures in the load-transmitting zone S1. In PEOFx, the calcium salt density was higher and the fat content was lower on the fractured side than on the intact side, indicating bony compacting due to lateral compression and fat displacement due to hematoma in the accident mechanism. This study makes an important contribution to the understanding of the development of sacral fragility fractures. Furthermore, impaction of the cancellous bone within the fracture can be demonstrated.

Biomechanical comparative study on external fixators of new configurations in the treatment of Tile C pelvic injury.

To compare the biomechanical properties of several anterior pelvic ring external fixators with two new configurations in the treatment of Tile C pelvic fractures, in order to evaluate the effectiveness of the new configurations and provide a reference for their clinical application. A finite element model of a Tile C pelvic ring injury (unilateral longitudinal sacral fracture and ipsilateral pubic fracture) was constructed. The pelvis was fixed with iliac crest external fixator (IC), anterior inferior iliac spine external fixator (AIIS), combination of IC and AIIS, combination of anterior superior iliac spine external fixator (ASIS) and AIIS, and S1 sacroiliac screw in 5 types of models. The stability indices of the anterior and posterior pelvic rings under vertical longitudinal load, left-right compression load and anterior-posterior shear load were quantified and compared. In the simulated bipedal standing position, the results of the vertical displacement of the midpoint on the upper surface of the sacrum are consistent with the displacement of the posterior rotation angle, and the order from largest to smallest is IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. The longitudinal displacement of IC is greater than that of the other models. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter is smaller. In the simulated semi-recumbent position, the vertical displacement and posterior rotation angle displacement of the midpoint on the upper surface of the sacrum are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Under the simulated left-right compression load state, the lateral displacements of the highest point of the lateral sacral fracture end are consistent with the highest point of the lateral pubic fracture end, and the order from large to small is S1 screw, IC, AIIS, ASIS + AIIS and IC + AIIS, among which the displacements of S1 screw and IC are larger, and the displacements of ASIS + AIIS and IC + AIIS are similar and smaller than those of other models. The displacements of IC + AIIS are smaller than those of ASIS + AIIS. Under the simulated anterior-posterior shear load condition, the posterior displacements of the highest point of the lateral sacral fracture end and the highest point of the lateral pubic fracture end are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Among them, the displacements of IC and AIIS are larger. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter are smaller. For the unstable pelvic injury represented by Tile C pelvic fracture, the biomechanical various stabilities of the combination of IC and AIIS are superior to those of the external fixators of conventional configurations. The biomechanical stabilities of the combination of ASIS and AIIS are also better than those of the external fixators of conventional configurations, and slightly worse than those of the combination of IC and AIIS. Compared with sacroiliac screw and conventional external fixators, the lateral stabilities of IC + AIIS and ASIS + AIIS are particularly prominent.