Anterior internal versus external fixation of unstable pelvis fractures was not associated with discharge destination, critical care, length of stay, or hospital charges.

PURPOSE: Determine if anterior internal versus supra-acetabular external fixation of unstable pelvic fractures is associated with care needs or discharge. METHODS: A retrospective cohort study was performed at two tertiary trauma referral centers. Adults with unstable pelvis fractures (AO/OTA 61B/61C) who received operative fixation of the anterior and posterior pelvic ring by two orthopedic trauma surgeons from October 2020 to November 2022 were included. The primary outcome was discharge destination. Secondary outcomes included intensive care unit (ICU) or ventilator days, length of stay, and hospital charges. RESULTS: Eighty-three eligible patients were 38.6% female, with a mean age of 47.2 ± 20.3 years and BMI 28.1 ± 6.4 kg/m2. Fifty-nine patients (71.1%) received anterior pelvis internal fixation and 24 (28.9%) received external fixation. External fixation was associated with weight-bearing restrictions (91.7% versus 49.2%, p = 0.01). No differences in demographic, functional status, insurance type, fracture classification, or injury severity measures were observed by treatment. Internal versus external anterior pelvic fixation was not associated with discharge to home (49.2% versus 29.2%, p = 0.10), median ICU days (3.0 [interquartile range (IQR) 7.8 versus 5.5 [IQR 4.3], p = 0.14, ventilator days (0 [IQR 6.0] versus 0 [IQR 2.8], p = 0.51), length of stay (13.0 [IQR 13.0] versus 17.5 (IQR 20.5), p = 0.38), or total hospital charges (US dollars 180,311 [IQR 219,061.75] versus 243,622 [IQR 187,111], p = 0.14). CONCLUSIONS: Anterior internal versus supra-acetabular external fixation of unstable pelvis fractures was not significantly associated with discharge destination, critical care, hospital length of stay, or hospital charges. This sample may be underpowered to detect differences between groups. LEVEL OF EVIDENCE: Therapeutic Level IV.

Delay of fixation increases 30-day complications and mortality in traumatic pelvic ring injuries.

PURPOSE: While decreased time to fixation in femur fractures improves mortality, it remains unclear if the same relationship exists for pelvic fractures. The National Trauma Data Bank (NTDB) is a data repository for trauma hospitals in the United States (injury characteristics, perioperative data, procedures, 30-day complications), and we used this to investigate early, significant complications after pelvic-ring injuries. METHODS: The NTDB (2015-2016) was queried to capture operative pelvic ring injuries in adult patients with injury severity score (ISS) ≥ 15. Complications included medical and surgical complications, as well as 30-day mortality. Multivariable logistic regression was used to investigate the association between days to procedure and complications after adjusting for demographic characteristics and comorbidities. RESULTS: 2325 patients met inclusion criteria. 532 (23.0%) sustained complications, and 72 (3.2%) died within the first 30 days. The most common complications were deep vein thrombosis (DVT) (5.7%), acute kidney injury (AKI) (4.6%), and unplanned intensive care unit (ICU) admission (4.4%). In a multivariate analysis, days to procedure was independently significantly associated with complications, with an adjusted odds ratio (95% confidence interval) of 1.06 (1.03-1.09, P < 0.001), best interpreted as a 6% increase in the odds of complication or death for each additional day. CONCLUSION: Time to pelvic fixation is a significant and modifiable risk factor for major complications and death. This suggests we should prioritize time to pelvic fixation on trauma patients to minimize mortality and major complications.

Integrity of the pectineal ligament in MRI correlates with radiographic superior pubic ramus fracture displacement.

BACKGROUND: Estimating the stability of pelvic lateral compression fractures solely by static radiographs can be difficult. In this context, the role of anterior pelvic soft tissues as potential secondary stabilizer of the pelvic ring has hardly been investigated. PURPOSE: To correlate the initial radiographic appearance of the pubic ramus fracture with the integrity of the pectineal ligament, a strong ligament along the pecten pubis. MATERIAL AND METHODS: In total, 31 patients with a pelvic lateral compression fracture (AO/OTA 61- B1.1/B2.1) with 33 superior pubic ramus fractures and available post-traumatic radiographs (pelvis anteroposterior, inlet, outlet) and magnetic resonance imaging (MRI) of the pelvis with fat-suppressed coronal images were reviewed retrospectively. Radiographic superior pubic ramus fracture displacement was measured and correlated to the degree of MR-morphologic alterations of the pectineal ligament (grade 0 = intact, grade 3 = rupture). RESULTS: In the majority of fractures (72.7%), associated MR-morphologic alterations of the pectineal ligament were present. Radiographic displacement and MRI grading showed a strong positive correlation (Spearman rho = 0.783, P < 0.001). The sensitivity and specificity for a radiographic displacement of >3 mm on plain radiographs to detect a structural ligament lesion on MRI (grade 2 and higher) were 73% and 100%, respectively. CONCLUSION: Radiographic displacement of superior pubic ramus fractures >3 mm is a strong indicator for a structural lesion of the pectineal ligament. Future studies should investigate the potential biomechanical importance of this ligament for pelvic ring stability.

A feasibility study of individual 3D-printed navigation template for the deep external fixator pin position on the iliac crest.

BACKGROUND: The aim of this study was to investigate the feasibility of an individual navigation template for the deep pin position on the iliac crest, based on digital design and 3D printing technology. METHODS: The preoperative CT images of 8 patients with pelvic fractures were collected. The data were reconstructed using a 3D imaging reconstruction workstation. An individual navigation template for the deep pin position on the iliac crest was designed on a virtual 3D model. The individual drill template and the solid pelvic model were produced using the 3D printing technology. The individual drill template was used for intraoperative deep pin position on the iliac crest after the preoperative simulation was completed. RESULTS: Thirty-two external fixator pins were inserted using the individual drill template. The average depth of pins was 84.82 mm. The trajectories were appropriate based on the postoperative X-ray and CT scan. No significant difference in the entry point, convergence angle, and caudal angle of the pins were noted before and after the operation (all P > 0.05). Finite element analysis indicated that the deep external fixator pin position could more reasonably distribute the stress in the cortical and spongy bones in the pelvis. All patients could perform partial weight-bearing activity 6 weeks postoperatively. No loosening and rupture of the pin, infection, and no damage of blood vessels and nervous tissue were found during the entire follow-up period. CONCLUSIONS: The individual drill template technique is an improvement of the traditional technique, which could increase precision and the depth of pin position. In addition, good mechanical stability and low risk of pin-related complications occurred due to the individual drill template, which makes the external fixation technique a potential alternative.

Major emergency orthopaedic surgery in patients with a concomitant acute coronary event following trauma.

INTRODUCTION: This paper is a short series description of our experience with five cases managed surgically for orthopaedic trauma and who suffered meanwhile an acute coronary event. MATERIALS AND METHODS: Five polytrauma, multiply fractured patients were treated in our institution for various lesions, including an open femur and knee articular fractures, major fractures around the pelvis and hips. They had suffered around the same time an acute coronary event complicating the orthopaedic management. One patient was treated for the orthopaedic condition as a delayed emergency, with a five day retard due to pre-operative pulmonary oedema. Four patients had cardiac evaluation, angiogram or echocardiogram. The patients were managed by a multi-disciplinary team. RESULTS: One patient died post-operatively due to multiple complications, and four patients survived with a good functional outcome. CONCLUSIONS: Patients with acute orthopaedic polytrauma presenting concomitant acute coronary events should be treated by multi-disciplinary teams, allowing early surgical management in a safe cardio-vascular and stable haemodynamic status.

Subcutaneous internal anterior fixation of pelvis fractures-which configuration of the InFix is clinically optimal?-a retrospective study.

INTRODUCTION: Subcutaneous internal fixation (InFix) has become a valid alternative for anterior fixation of pelvic ring injuries. Complications associated with this technique are lateral femoral cutaneous nerve (LFCN) irritation and anterior thigh pain due to prominent implants. The aim of this study was to identify a configuration of the InFix that causes the least adverse side effects. METHODS: Nineteen patients (6 females, mean age 61 years) with 38 hemipelves were included. Rod-to-bone distance and symphysis-rod distance were measured on AP- and outlet- radiographs. These distances were analyzed in relation to the primary outcomes: early removal of the InFix, post-operative complications and damage of the LFCN. RESULTS: Regarding rod-to-bone distance, a distance of 20 to 25 mm causes less complications, LFCN damage and no early removals of the InFix. Symphysis-to-rod distance analysis showed the best results regarding LFCN damage and other complications when the rod had a distance of less than 40 mm to the symphysis. A distance more than 40 mm was associated with fewer early removal of the InFix. CONCLUSIONS: Planned optimized configuration of the InFix with a rod-to-bone distance between 20 and 25 mm may reduce postoperative complications. Regarding LFCN damage, the rod-to-symphysis distance should not be more than 40 mm.

Occult injuries of the contralateral sacroiliac joint in operatively treated pelvis fractures: incidence, root cause analysis, and proposal of treatment algorithm.

PURPOSE: To determine the most common injury patterns, root cause, and the frequency with which unrecognized contralateral posterior ring injury occurs in patients presenting with surgically treated pelvic fractures. METHODS: The medical records of 73 patients presenting to our level I trauma center (52 male and 21 female patients; mean age 41.8 years; range 18-89 years) with surgically treated pelvic ring fractures between January 1, 2016 and January 1, 2018 were reviewed. Patient demographics, mechanism of injury, associated injuries, imaging prior to binder or external fixation, use of temporary stabilization with pre-peritoneal pelvic packing (PPP) and anterior pelvic external fixation, and fracture pattern were recorded and analyzed to identify independent risk factors contributing to occult contralateral missed posterior ring injury. RESULTS: Occult contralateral pelvic ring injuries occurred in 6/72 patients (8.2% incidence). Pelvis fractures in multiply traumatized patients with associated orthopaedic injuries were associated with higher prevalence of occult contralateral pelvic ring injury (relative risk 1.85, 95% CI 1.13-3.02) as compared to patients with isolated pelvic fractures. CONCLUSIONS: There is an 8.2% incidence of unrecognized contralateral SI joint instability in patients presenting with unstable pelvic ring injuries. Multiply traumatized patients with multiple orthopaedic injuries were an independent risk factor for this injury pattern.

Complications after percutaneous internal fixator for anterior pelvic ring injuries.

OBJECTIVES: The aim of the study is to report on the observed incidence of complications following pedicle screw and rod internal fixator (INFIX) stabilization of pelvic ring fractures. METHODS: In a retrospective review of consecutive patient series conducted in a University level 1 trauma hospital, 43 patients (21 female and eight male), mean age 64.2 (range 16-87) with OTA/AO type B or C pelvic ring fractures received percutaneous pedicle screw and rod internal fixator (INFIX) anterior stabilization of pelvic ring fractures; 29 fulfilled inclusion criteria with three months' minimal follow-up or known complication. Mean follow-up was 7.2 months. Main outcome measure was the incidence of complications and adverse outcomes. RESULTS: Fourteen (48.3%) had injury to the lateral femoral cutaneous nerve (LFCN). Three (10.3%) had chronic pain of the pelvis not related to the LFCN. Five out of 29 (17%) of patients had unplanned removal before six weeks with two due to early loosening, one femoral nerve palsy, one deep infection and one painful implant impingement. There were no patients with deep vein thrombosis, no intra-abdominal violations or vascular complications; 22 (76%) returned to their premorbid walking status. CONCLUSION: With high risk of LFCN injury, we caution against liberal use of the INFIX in patients with stable fractures where conservative treatment may be more appropriate. Most complications occurring from INFIX are self-limiting.

Patterns of injury and management of children with pelvic fractures at a non-trauma center.

BACKGROUND: Pelvic injuries in young children are rare, and it has been difficult to establish clinical guidelines to assist providers in managing blunt pelvic trauma, especially in non-Level 1 trauma centers. OBJECTIVE: Our aim was to describe the relationship among clinical findings, mechanism of injury, and the radiographic resources utilized in children with pelvic fractures presenting to a non-Level 1 trauma center. METHODS: A retrospective review of patients with a pelvic fracture treated in two urban pediatric Level 3 emergency departments was performed. RESULTS: Between 2001 and 2010, a total of 208 patients were identified. Avulsion/iliac wing fractures were the most common fractures (58.7%), and sports-related injuries were the most common mechanism of injury (50.0%). Children with sports-related injuries were more likely to sustain an avulsion fracture (p<0.001), less likely to have a computed tomography scan obtained in the emergency department (p<0.001), and less likely to have an associated injury (p<0.001) than other children. Children struck by a motor vehicle (p<0.001) or involved in a motor vehicle accident (p<0.001) were more likely to receive a computed tomography scan (p<0.001) and have associated head and extremity injuries (p<0.001). Mechanism of injury was associated with abnormal computed tomography scans. Nearly all patients were treated nonoperatively (98.1%) and no deaths were reported in this study. CONCLUSIONS: Patterns of injury, based on mechanism of injury, have been reported to assist the assessment and management of children with minor pelvic injuries.

Impact of introducing 3D printing-assisted surgery into clinical practice for traumatic pelvic and acetabular fractures.

Background: Given the novelty of three-dimensional (3D) printing-assisted fracture surgery in orthopaedics, surgeon familiarity is limited and learning curve is high. As such, it is unclear how the introduction of 3D printing into clinical practice for pelvic and acetabular fracture surgery would impact perioperative outcomes. The aim of this study was to determine the impact of introducing 3D printing-assisted surgery on perioperative outcomes for traumatic pelvic and acetabular fractures. Methods: We retrospectively identified consecutive patients who underwent surgical fixation of traumatic pelvic and acetabular fractures from 2018 to 2022 at a single tertiary hospital. The patients included in the study were divided into two groups: (1) 3D printing-assisted surgery and (2) conventional surgery. Baseline demographics and perioperative outcomes of total surgical duration, estimated blood loss, blood transfusion, number fluoroscopy images, fluoroscopy duration and postoperative disposition were recorded and compared between the two groups. Results: In total, 26 patients were included in the present study, with 3D printing-assisted surgery being used in 34.6 % (n = 9) of cases. There were no significant differences in baseline demographics or fracture type between the 3D printing group and conventional group. As compared to patients who underwent conventional surgery, those that underwent 3D printing-assisted surgery had, on average, shorter surgical duration (299.8 ± 88.2 vs 309.1 ± 143.1 min), lesser estimated blood loss (706.3 ± 330.0 vs 800.0 ± 584.2 ml), lower transfusion rates (50.0 % vs 52.9 %), lower number of intraoperative fluoroscopy images (62.8 ± 74.5 vs 71.6 ± 47.9 images) and shorter fluoroscopy duration (235.0 ± 79.2 vs 242.3 ± 83.5 min), although statistical significance was not achieved. None of the patients in the present study developed surgical complications postoperatively. Conclusion: The introduction of 3D printing-assisted surgery in clinical practice for pelvic and acetabular fractures is a safe and viable adjunct in pelvic and acetabular surgery, achieving comparable perioperative outcomes in the initial phase.

Comparative analysis of venous thromboembolic complications in diverse groups of orthopaedic patients.

INTRODUCTION AND OBJECTIVE: Venous thromboembolism (VTE) is one of the most important and life-threatening complications in orthopaedic surgery. According to current scientific reports, there are several variables that can affect the severity of CVD, including the site of the pathology or the type of treatment implemented. The aim of the study was to analyze the risk of VTE depending on the location of the pathology, as well as to evaluate the impact of surgical treatment compared to conservative management. MATERIAL AND METHODS: Analysis of laboratory results and clinical picture of 276 patients hospitalized for orthopaedic reasons, admitted between January 2008 - December 2019, with suspected pulmonary embolism (PE). RESULTS: Among patients diagnosed with PE, the most common location of the disease was in the lower limb 59/116 (50.9%), followed by the pelvis location - 22/116 (19.0%), the spine - 19/116 (16.4%), disseminated lesions in oncological patients - 12/116 (10.3%), and a group of pathologies in the upper limb - 4/116 (3.5%). Significant statistical differences were found between the incidence of PE and the diagnosis of pathology in the lower limb and the pelvis. In the group of patients, there was no statistically significant relationship between the incidence of PE associated with surgical treatment, compared to conservative management. CONCLUSIONS: The group with the highest risk of VTE were lower limb and pelvic pathologies. The results are largely consistent with numerous reports treating the risk of CVD among orthopaedic patient populations.

Orthopaedic fracture surgery in polytraumatized patients while on extracorporeal membrane oxygenation (ECMO): A report of two cases.

Extracorporeal membrane oxygenation (ECMO) has become a salvage therapy for patients with severe acute respiratory distress syndrome (ARDS). The management of orthopaedic trauma in ECMO-supported patients with ARDS remains an evolving area of interest. Orthopaedic injuries are often temporized with external fixators, skeletal traction, or splints due to hemodynamic instability as well as concerns of exacerbating underlying pulmonary injury. However, patients requiring ECMO support do not rely on their pulmonary system for oxygenation, the need for delayed fixation may not apply. However, patients utilizing ECMO therapy can have external cardiac and pulmonary support depending on their cannulation strategy, bypassing the need for delayed fixation. We present a case series of two polytrauma patients with ARDS who underwent surgical management of pelvic ring and femoral shaft fractures while receiving ECMO support. Both patients underwent surgical management without complication and were able to be weaned from ECMO and ventilator support postoperatively. These cases highlight the potential benefits to orthopaedic fixation and underscore the need for further clinical research.

Duverney's Fracture Fixed by Skiver Screw in a Skeletally Immature Patient: A Case Report.

Duverney's fracture, an eponym for isolated iliac wing fracture, is rather an uncommon fracture in the subset of pelvic ring fracture in the AO/OTA (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association) classification. Here, we discuss a more unique case with Duverney's fracture since the patient is a 15-year-old school-going girl with unfused physis of the ilium. After other injuries were ruled out, she underwent open reduction and fixation with a screw by the Skiver method augmented with the plate. Postoperatively, she was mobilized, and follow-up at eight months showed radiologically complete union with good functional outcome.

Management of Pelvic Trauma.

Pelvic fractures are common after blunt trauma with patients' presentation ranging from stable with insignificant fractures to life-threatening exsanguination from unstable fractures. Often, hemorrhagic shock from a pelvic fracture may go unrecognized and high clinical suspicion for a pelvic source lies with the clinician. A multidisciplinary coordinated effort is required for management of these complex patients. In the exsanguinating patient, hemorrhage control remains the top priority and may be achieved with external stabilization, resuscitative endovascular balloon occlusion of the aorta, preperitoneal pelvic packing, angiographic intervention, or a combination of therapies. These modalities have been shown to reduce mortality in this challenging population.

Late surgical correction after complex unstable pelvic fracture 61 C3 (OTA/AO) of an 18-year-old woman.

Surgical fixation of pelvic fractures is often necessary to restore fracture stability and improve patient outcomes. However, early operative management of pelvis fractures is not widely available in many health systems, resulting in conservative treatment approaches. Conservative approaches can lead to uncorrected pelvic deformities, which are challenging to treat and increase the risk of serious complications such as malunion. Treatment of pelvic malunion requires specialized care, access to necessary equipment, and a clearly defined treatment protocol. However, there is a lack of literature describing treatment algorithms for pelvic fracture malunion. This case report aims to incrementally fill this gap in the literature and highlight a logical step-by-step approach for reconstruction of pelvic malunion. This report is a single case of an 18-year-old woman who sustained complex unstable pelvic fracture, indicated for a 3-step reconstruction at a hospital with limited resources but access to computed tomography scan and some specialized pelvis reduction instruments. Postoperative imaging of the pelvis indicated satisfactory reduction and stable fixation of the pelvic reconstruction. After surgery, the patient was able to perform full axial load with no reported pain. This report provides a detailed description of each step of the operative management of a pelvic malunion case with clearly defined sequences, reduction tools, and positioning maneuvers necessary. Demonstrated in this case report, strategic preoperative planning is critical to successfully treating pelvic malunion and improving patient outcomes. This case report provides the necessary information on the management of pelvic reconstruction to inform other surgeons in underserved regions.

[Effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeâ ¡scapular pelvis fracture].

OBJECTIVE: To analyze the effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture. METHODS: From January 2016 to June 2021, 26 patients with Ideberg typeⅡglenoid fractures were treated with trans-axillary lag screw combined with supporting plate, including 15 males and 11 females. The age ranged from 21 to 75 years, with an average of (43.12±6.56) years old. The Constant-Murley Shoulder joint Scale and University of California at Los Angeles (UCLA) score were used to evaluate the function and clinical efficacy of shoulder joint. RESULTS: All patients were followed up, and the duration ranged from 19 to 42 months, with an average of (30.6±10.5) months. One year after surgery, the Constant-Murley score increased from preoperative 34.9±2.5(ranged, from 28 to 47) to 87.2±6.8(ranged, from 70 to 95). The UCLA score improved from preoperative 17.9±1.7(9 to 25) to 33.1±2.3(29 to 35). Seventeen patients got an excellent result, with 7 good, and 2 fair. None of the patients had infection, screw, and plate loosening, fracture, and other complications after surgery. Two patients had different degrees of Chronic pain in the shoulder during the follow-up period. CONCLUSION: The treatment of Ideberg typeⅡscapular glenoid fractures through axillary approach with lag screws and supporting steel plates has the advantages of convenient exposure, direct visual restoration of the normal anatomical shape of the scapular glenoid, selection of suitable positions for screw and steel plate placement, achieving better treatment results, and fewer complications. It is an effective and reliable surgical method.

Delayed Presentation of Sciatic Nerve Palsy Due to Post-traumatic Pseudoaneurysm Following Pelvis Fracture: A Case Report.

Introduction: Pseudoaneurysms are vascular lesions occurring after injury to a blood vessel wall. Peripheral artery pseudoaneurysms as a fracture complication are uncommon and typically appear immediately after trauma or surgery. We report a unique case of sciatic nerve palsy associated with external iliac artery pseudoaneurysm arising 20 years after pelvic trauma, presenting within the fracture site as an erosive bone lesion masquerading as a possible malignancy. To the best of our knowledge, no cases of delayed external iliac artery pseudoaneurysm involving sciatic pain have been reported. Case Report: We present a 78-year-old female who sustained an acetabular fracture with an uneventful recovery for 20 years. The patient presented post-injury with symptoms and physical examination findings consistent with sciatic nerve palsy. Computed tomography angiography and duplex imaging revealed a pseudoaneurysm of the external iliac artery. The patient was taken to the operating room for endovascular repair of the external iliac artery using a covered stent. Conclusion: This case of sciatic nerve palsy is a unique contribution to the literature concerning the specific vascular injury observed and the delayed presentation of pseudoaneurysm causing sciatic nerve palsy. Orthopedic surgeons must consider a wide differential when confronted with suspicious pelvic masses. Failure to diagnose these as a vascular etiology could prove catastrophic should the surgeon attempt an open debridement or sampling.

Significant improvement in axial load stability with the pre-tensioned pelvic external fixator: A biomechanical analysis in a model with type C Tile lesion. / Mejora significativa de la estabilidad a carga axial con el fijador externo pélvico pretensado: análisis biomecánico en un modelo con lesión Tile tipo C.

OBJECTIVE: The aim of our work is to check if the use of a pre-tensed bar connected to 2supra-acetabular Schanz pins is more stable in a pelvic with a tile C1 injury. MATERIAL AND METHODS: We used synthetic pelvis (N=5) with a unstable vertical injury, stabilized with both the standard and the pre-tensed system. They both were submitted to axial loading. We measured applied forces and the position of markers that were positioned in the sacroiliac and symphysis joints. We determined the relative movements between injured surfaces, rigidity, resistance and when each system failed. RESULTS: When using the pre-tensed fixator, the rigidity was much higher in the sacro-iliac joint (P=.043) being 3.45 times higher, being also 2.06 times higher in pubic symphysis (P=.043). The resistance against failure was 2 times higher too (P=.043). DISCUSSION: The increased axial stability with the pre-tensed external fixator accords with its ability to make active compression in both posterior and anterior elements of the pelvic ring, which was previously demonstrated. This result supports the preliminary clinic outcomes that were obtained. CONCLUSIONS: The pre-tensed external fixator increases the axial stability of the pelvic ring's posterior elements in a synthethic pelvis with a Tile C1 injury, without decreasing it's capacity to achieve an anterior stability.

[Translated article] Significant improvement in axial load stability with the pre-tensioned pelvic external fixator: A biomechanical analysis in a model with type C Tile lesion.

OBJECTIVE: The aim of our work is to check if the use of a pre-tensed bar connected to 2 supra-acetabular Schanz pins is more stable in a pelvic with a tile C1 injury. MATERIAL AND METHODS: We used synthetic pelvis (N = 5) with a unstable vertical injury, stabilized with both the standard and the pre-tensed system. They both were submitted to axial loading. We measured applied forces and the position of markers that were positioned in the sacroiliac and symphysis joints. We determined the relative movements between injured surfaces, rigidity, resistance and when each system failed. RESULTS: When using the pre-tensed fixator, the rigidity was much higher in the sacro-iliac joint(P=.043) being 3.45 times higher, being also 2.06 times higher in pubic symphysis (P=.043). The resistance against failure was 2 times higher too (P=.043). DISCUSSION: The increased axial stability with the pre-tensed external fixator accords with its ability to make active compression in both posterior and anterior elements of the pelvic ring, which was previously demonstrated. This result supports the preliminary clinic outcomes that were obtained. CONCLUSIONS: The pre-tensed external fixator increases the axial stability of the pelvic ring's posterior elements in a synthethic pelvis with a Tile C1 injury, without decreasing it's capacity to achieve an anterior stability.

Risk factors for loss to follow up of pelvis and acetabular fractures.

INTRODUCTION: Pelvic and acetabular fracture incidence is increasing worldwide for more than four decades. There is currently no evidence examining risk factors for loss to follow up in patients with these injuries. METHODS: Patients presenting with pelvic and/or acetabular fractures at our institution between 2015 and 2020 were included. Demographic, injury, treatment, and follow up information was included. Excluded patients were those who sustained a pathologic fracture, has a course of treatment prior to transfer to our centre, or expired prior to discharge. RESULTS: 446 patients, 263 with a pelvic ring injury, 172 with an acetabular fracture, and 11 with combined injuries were identified. 271 (61%) of patients in our cohort followed up in Orthopaedic clinic (p = 0.016). With an odds ratio of 2.134, gunshot wound mechanism of injury was the largest risk factor for loss to follow up (p = 0.031) followed by male sex (OR= 1.859) and surgery with general trauma surgery (OR=1.841). The most protective risk factors for follow up with Orthopaedic surgery were operatively treated pelvic and acetabular fractures (OR=0.239) and Orthopaedic Surgery as the discharging service (OR=0.372). DISCUSSION: Numerous risk factors exist for loss to follow up including male sex, ballistic mechanism, and discharging service. Investigation into interventions to improve follow up in these patients are warranted.