Supra-acetabular External Fixation Research Articles

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

Determine if anterior internal versus supra-acetabular external fixation of unstable pelvic fractures is associated with care needs or discharge. 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. Eighty-three eligible patients were 38.6% female, with a mean age of 47.2 ± 20.3years and BMI 28.1 ± 6.4kg/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). 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. Therapeutic Level IV.

Experimental and numerical assessment of two reconstructive techniques for the fragility fractures of the pelvis type Ia.

Anterior pelvic ring fractures are common in geriatric patients. The Supraacetabular External Fixator (SEF) is a relatively simple and effective surgical procedure. On the other hand, there is the option of a Subcutaneous Iliopubic Plate (SIP) osteosynthesis. Only limited comparative biomechanical data of these two devices are available. Therefore, this biomechanical study's objective was to compare the stabilizing effect of the SEF versus the SIP in a model of Fragility Fractures of the Pelvis (FFP) type Ia. A test stand for pelvic biomechanics testing that emulates the gait loading cycle with physiological relevance was used. The osteotomy on the right pelvic ring was stabilized either with the SEF or the SIP. Strain gauges were used to measure strain in the pelvic ring. The osteotomy's spatial interfragmentary displacement (SID) was monitored using a 3D digital image correlation system. The SEF stabilization reduced the SID by approximately 10%, whereas the locking SIP could reduce displacement by about 62%. Additionally, the SIP reduced the stress/strain levels by 67% in the posterior pelvic ring. We could demonstrate that the SIP is superior to SEF in treating FFP type Ia as it significantly reduced the osteotomy's SID and the strain in the posterior pelvic ring.

Internal fixator vs external fixator in the management of unstable pelvic ring injuries: A prospective comparative cohort study.

Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently. There is a debate on using either an anterior subcutaneous pelvis internal fixator (INFIX) or an anterior supra-acetabular external fixator (EXFIX) to manage an unstable anterior pelvic ring fracture. To compare the functional and radiological outcomes and complications of INFIX vs EXFIX in managing unstable pelvic ring injuries. A prospective cohort study included 54 patients with unstable pelvic ring fractures. The patients were divided into two groups; the INFIX group, in which 30 cases were fixed by INFIX, and the EXFIX group, in which 24 patients were treated by EXFIX. The average age in the EXFIX group was 31.17 years (16-57 years), while in the INFIX group, it was 34.5 years (17-53 years). The study included 20 (66.7%) males and 10 (33.3%) females in the INFIX group and 10 (41.7%) males and 14 (58.3%) females in the EXFIX group. The radiological outcomes were evaluated using Matta and Tornetta's score, and the functional outcomes using the Majeed score. The results revealed a statistically significant difference between both groups (P = 0.013) regarding radiological outcomes, according to Matta and Tornetta's score in favor of the INFIX group. Sitting, standing, and walking abilities were measured at a 3-mo follow-up visit using Majeed score modules. It was significantly better among the INFIX group than the EXFIX group in all three modules. At the final follow-up, both groups had no statistically significant difference according to the Majeed score; 92.35 in the INFIX group and 90.99 in the EXFIX group (P = 0.513). A lower surgical site infection rate was noticed in the INFIX group (P = 0.007). Anterior subcutaneous pelvis INFIX is associated with better radiological outcomes and a lower infection rate than anterior supra-acetabular EXFIX in managing patients with unstable anterior pelvic ring fractures.

Does Cement Augmentation of the Sacroiliac Screw Lead to Superior Biomechanical Results for Fixation of the Posterior Pelvic Ring? A Biomechanical Study.

Background and Objectives: The stability of the pelvic ring mainly depends on the integrity of its posterior part. Percutaneous sacroiliac (SI) screws are widely implanted as standard of care treatment. The main risk factors for their fixation failure are related to vertical shear or transforaminal sacral fractures. The aim of this study was to compare the biomechanical performance of fixations using one (Group 1) or two (Group 2) standard SI screws versus one SI screw with bone cement augmentation (Group 3). Materials and Methods: Unstable fractures of the pelvic ring (AO/OTA 61-C1.3, FFP IIc) were simulated in 21 artificial pelvises by means of vertical osteotomies in the ipsilateral anterior and posterior pelvic ring. A supra-acetabular external fixator was applied to address the anterior fracture. All specimens were tested under progressively increasing cyclic loading until failure, with monitoring by means of motion tracking. Fracture site displacement and cycles to failure were evaluated. Results: Fracture displacement after 500 cycles was lowest in Group 3 (0.76 cm [0.30] (median [interquartile range, IQR])) followed by Group 1 (1.42 cm, [0.21]) and Group 2 (1.42 cm [1.66]), with significant differences between Groups 1 and 3, p = 0.04. Fracture displacement after 1000 cycles was significantly lower in Group 3 (1.15 cm [0.37]) compared to both Group 1 (2.19 cm [2.39]) and Group 2 (2.23 cm [3.65]), p ≤ 0.04. Cycles to failure (Group 1: 3930 ± 890 (mean ± standard deviation), Group 2: 3676 ± 348, Group 3: 3764 ± 645) did not differ significantly between the groups, p = 0.79. Conclusions: In our biomechanical setup cement augmentation of one SI screw resulted in significantly less displacement compared to the use of one or two SI screws. However, the number of cycles to failure was not significantly different between the groups. Cement augmentation of one SI screw seems to be a useful treatment option for posterior pelvic ring fixation, especially in osteoporotic bone.

The role of anterior supra-acetabular external fixator as definitive treatment for anterior ring fixation in unstable pelvic fractures.

Management of anterior ring injuries is still a matter of discussion, and there are only few studies reporting anterior external fixator as definitive treatment for unstable pelvic injuries. This study aimed to describe the clinical and radiological outcomes of a consecutive series of mechanically unstable pelvic injuries that were treated with definitive anterior supra-acetabular external fixator for the anterior ring, and to identify risk factors for failure. We included a consecutive series of patients with unstable pelvic ring fractures who underwent anterior supra-acetabular external fixation for definitive treatment, between January 2012 and January 2020. All demographics, associated injuries and procedures, injury mechanism, and complications were analysed. Pelvic fracture was classified based on Orthopaedic Trauma Association/Tile AO (OTA/AO) and Young-Burgess classifications. Complications associated with the external fixator were revised. All patients were functionally evaluated at final follow-up and asked to report their clinical outcomes using the Majeed score. A total of 47 patients were included, of which 25 were females. The median age was 44years (interquartile range 23-59). Median follow-up duration was 14months (interquartile range 6-31). The most frequent aetiology was motor vehicle accident (35), followed by fall from height (8). All fractures required posterior pelvic ring fixation. The median time during which patients had external fixation in situ was 11weeks (interquartile range 9-13). All patients achieved healing of pelvic fracture at median time of 10weeks (interquartile range 8-12). At final follow-up, the median displacement of the anterior pelvis was 6mm (interquartile range 0-11). Superficial infection was the most common complication (n = 7). No washout procedures were needed. No major complication was reported. No patient required reoperation for anterior ring fracture. The median Majeed score was 88 points (range 60-95; interquartile range 80-90) at final follow-up. Our findings suggest that the use of supra-acetabular external fixator is safe and effective for definitive treatment of the anterior ring in unstable pelvic fractures. It is a method with high proportion of excellent results, regardless of the type of fracture. The rate of complications is low, and it does not compromise functional results.

Biomechanical Comparison of Five Fixation Techniques for Unstable Fragility Fractures of the Pelvic Ring.

Background: Incidence of pelvic ring fractures has increased over the past four decades, especially after low-impact trauma—classified as fragility fractures of the pelvis (FFP). To date, there is a lack of biomechanical evidence for the superiority of one existing fixation technique over another. An FFP type IIc was simulated in 50 artificial pelvises, assigned to 5 study groups: Sacroiliac (SI) screw, SI screw plus supra-acetabular external fixator, SI screw plus plate, SI screw plus retrograde transpubic screw, or S1/S2 ala–ilium screws. The specimens were tested under progressively increasing cyclic loading. Axial stiffness and cycles to failure were analysed. Displacement at the fracture sites was evaluated, having been continuously captured via motion tracking. Results: Fixation with SI screw plus plate and SI screw plus retrograde transpubic screw led to higher stability than the other tested techniques. The S1/S2 ala–ilium screws were more stable than the SI screw or the SI screw plus external fixator. Conclusions: In cases with displaced fractures, open reduction and plate fixation provides the highest stability, whereas in cases where minimally invasive techniques are applicable, a retrograde transpubic screw or S1/S2 ala–ilium screws can be considered as successful alternative treatment options.

Comparison of iliac crest versus supraacetabular external fixator in hemodynamically unstable patients with a pelvic ring injury.

External fixation has been widely implemented as a resuscitation strategy in combination with pelvic packing for high energy, hemodynamically unstable, pelvic ring injuries. The primary aim of this study is to compare urgent iliac crest (IC) versus supraacetabular (SA) external fixation in the setting of haemodynamic instability. This is a retrospective review of a prospectively gathered registry at an urban level one trauma centre comparing placement of pelvic external fixator by SA or IC technique. Outcomes assessed were accuracy of pin placement, duration of procedure, and the effect on true pelvic circumference depending on type of fracture by Young and Burgess Classification system. Ninety-three haemodynamically unstable patients with a pelvic fracture included. Pin malpositioning was more common with IC than SA groups (proportional difference, - 40%; 95% CI, - 57 to - 20%; p < 0.0001). For APC injuries, there was a larger median reduction in pelvic circumference in the SA group than the IC group (median difference [MD], - 12.85cm; 95% CI, - 27 to 0.1; p = 0.0485). In LC injuries, the SA group had an overall increase in pelvic circumference compared to an overall decrease in IC group (MD, 6.5cm; 95% CI, 1.5 to 16.8; p = 0.0221). There was no difference in the operating room (OR) time (mean difference, - 5.4min; 95% CI, - 32 to 22; p = 0.68). In this clinical setting, we recommend placement of SA external fixator (versus IC) with similar operative times, fewer pin malpositions, and improved stabilization of pelvic circumference in APC and LC injuries.

Optimal pin position in supraacetabular external fixation.

This study focuses on (i) the length of the intraosseous part of the supraacetabular pin using the insertion technique from the spina iliaca anterior inferior to the cortical part of the incisura ischiadica major, (ii) the angle of insertion of the supraacetabular pin in the transversal plane and (iii) gender-specific differences of the measured results. Images of uninjured pelves from 49 patients (64-line computed tomography scanner) were evaluated, and virtual external fixator pins were positioned using a three-dimensional reconstructions of computed tomography scans. The length of the pins and the insertion angle were investigated. Descriptive statistics were used, and gender-specific differences were calculated. A P-value of <0.05 was considered statistically significant. The results showed significant differences between male and female pelves concerning both pin length and insertion angel. For male pelves, the mean screw length was 82.7 mm (SD 5.1; range 72.9-94.3). For females, this was statistically significantly shorter (P ≤ 0.001), with an average of 74.1 mm (SD 5.0; range 63.1-81.9). In the male subgroup, the insertion angle was a mean of 22.6° (SD 3.4; range 12.4-31.8), and the female pelves had an average angle of 19.7° (SD 4.0; range 11.7-24.5). These values differed statistically significantly (P = 0.0032). Based on our measurements, we can confirm that both the length of the Schanz screws and the angle of insertion for the supraacetabular external fixator show a statistically significant difference between males and females.

Secondary Angio-Embolization After Emergent Pelvic Stabilization and Pelvic Packing Is a Safe Option for Patients With Persistent Hemorrhage From Unstable Pelvic Ring Injuries.

Introduction: In patients with severe pelvic ring injuries, exsanguination still is the leading cause of death in the early post-injury phase. While mechanical pelvic ring stabilization and pre-peritoneal pelvic packing are mainly addressing venous bleeding, angio-embolization aims to control arterial bleeding. The goal of the present study was to evaluate the rate of postoperative angio-embolization after mechanical pelvic ring injury stabilization and pre-peritoneal pelvic packing. Bleeding sources detected in the angiography and the patient's outcome were investigated.Patients and Methods: Retrospective observational cohort study at a single academic level I trauma center, reviewing all patients with pelvic ring injuries admitted from 01/2010 to 12/2019. Patients with emergent mechanical pelvic ring stabilization (supraacetabular external fixator and/or pelvic C-clamp) and direct pre-peritoneal pelvic packing were further analyzed. Patients that underwent postoperative angio-embolization were compared with those that did not. All postoperative angio-embolizations were evaluated with regards to bleeding sources and type of embolization.Results: During the study period, a total of 39 patients required immediate mechanical pelvic stabilization and direct pre-peritoneal pelvic packing. Of these, 12 patients (30.8%) underwent a postoperative angio-embolization. The following vessels were identified as bleeding sources: superior gluteal artery (n = 6), obturator artery (n = 2), internal pudendal artery (n = 2), unnamed branches of the internal iliac artery (n = 3). A selective embolization was successful in 11 patients; in 1 patient, an unilateral complete occlusion of the internal iliac artery was performed to control the bleeding. Mean time from hospital admission to the surgical procedure was 52.8 ± 14.7 min and the mean time from admission to angio-embolization was 189.1 ± 55.5 min. The in-hospital mortality rate of patients with angio-embolization was 25.0% (n = 3). Of these, 2 patients died due to multiple organ failure and 1 patient due to severe head injury.Conclusion: Secondary angio-embolization after external pelvic fixation and pre-peritoneal pelvic packing was effective in controlling ongoing bleeding. The most frequently detected bleeding vessel was the superior gluteal artery, which is difficult to surgically address, further highlighting the importance of angio-embolization in the management algorithm.

Anterior supra-acetabular external fixation for tile C1 pelvic fractures: a digital anatomical study and a finite element analysis.

Investigating the anatomical characteristics of supra-acetabular screw corridor as well as comparing the biomechanical stability between semi- and full-length screw external fixations for Tile C1 pelvic fractures. 50 male and 50 female uninjured pelvic CT data were converted into three-dimensional models and the supra-acetabular corridors were reconstructed by the Mimics software. The horizontal slice was redefined passing through the bilateral anterior inferior iliac spine and bilateral posterior superior iliac spine at the same time. On every horizontal slices, a 5mm diameter virtual screw was placed along with the unilateral anterior narrowing to posterior narrowing of the supra-acetabular corridor, and the relevant parameters of the semi- and full-length screw fixations were measured from inferior to superior at an interval height of 2.5mm until the width of the corridor was less than 5mm. Thus, the insertion position was located, as well as the inclination angle ranges were measured. The same procedure was done on a bilateral supra-acetabular corridor for each patient. Last, a Tile C1 pelvic finite element model was simulated and fixed with either semi- or a full-length anterior supra-acetabular external fixator. A 500N loading was tested on the model with three directions (cranial-caudal, anterior-posterior and lateral-medial) and the stiffness was determined by the max displacements. The insertion points of supra-acetabular screw for 66% (66/100) of men and 78% (78/100) of women were located at the outer lower part of the anterior inferior iliac spine (AIIS) (p < 0.001). The medial inclination angles of the screw were 29.50 ± 4.05° for men and 28.00 ± 3.78° for women (p = 0.007). The cranial inclination angles of the screw were 29.40 ± 5.38° for men and 28.57 ± 6.01° for women (p = 0.306). The safe inclination angle ranges of the semi-length screw were 3°-6° bigger than the full-length screw. For semi-length corridor, the widths were 14.07 ± 2.39mm for men and 11.29 ± 1.81mm for women (p < 0.001) and the depths were 71.77 ± 5.96mm for men and 69.26 ± 5.21mm for women (p < 0.001). For full-length corridor, the widths were 10.61 ± 2.10mm for men and 8.44 ± 2.03mm for women (p < 0.001) and the depths were 133.37 ± 7.60mm for men and 129.01 ± 8.12mm for women (p < 0.001). In the finite element analysis, the max displacements of the pelvis under three loading modes (cranial-caudal, anterior-posterior and lateral-medial) for semi-length fixation were 0.772mm, 0.409mm and 0.331mm and for full-length fixation were 0.727mm, 0.385mm and 0.262mm. The outer lower part of AIIS is recommended as an insertion point of the supra-acetabular screw with about 30° medial and cranial inclination angles, and the semi-length screw is safer for placing and has satisfactory biomechanical stability by compared with a full-length screw.

The T-pod is as stable as supraacetabular fixation using 1 or 2 Schanz screws in partially unstable pelvic fractures: a biomechanical study

IntroductionUnstable fractures of the pelvis remain the predominant cause of severe hemorrhage, shock and early death in severely injured patients. The use of pelvic binders has become increasingly popular, particularly in the preclinical setting. There is currently insufficient evidence available about the stability of the pelvic binder versus supraacetabular fixation using 1 or 2 Schanz screws. We aimed to analyze the stability of the pelvic binder and supraacetabular fixateurs using either 1 or 2 Schanz screws in a cadaver model of an induced pelvic B-type fracture.Materials and methodsThe study was undertaken in 7 human fresh-frozen cadaveric pelvises with induced AO-type B fractures. Three stabilization techniques were compared: T-POD (pelvic bandage), supraacetabular external fixator with 1 pin on each side and external fixator with 2 pins on each side. Stability and stiffness were analyzed in a biomechanical testing machine using a 5-step protocol with static and dynamic loading, dislocation data were retrieved by ultrasound sensors at the fracture sites.ResultsNo significant differences in fracture fragment displacement were detected when using either the T-POD, a 1-pin external fixator or a 2-pin external fixator (P > 0.05). The average difference in displacement between the three methods was < 1 mm.ConclusionsPelvic binders are suitable for reduction of pelvic B-type fractures. They provide stability comparable to that of supraacetabular fixators, independently of whether 1 or 2 Schanz screws per side are used. Pelvic binders provide sufficient biomechanical stability for transferring patients without the need to first replace them with surgically applied external fixators. However, soft tissue irritation has to be taken into consideration and prolonged wear should be avoided.Level of evidenceLevel III

Biomechanical comparison of supraacetabular external fixation and anterior pelvic bridge plating

Unstable pelvic ring injuries are complex and risky injuries due to high morbidity and mortality. Although anterior pelvic external fixator is a suitable method for rapid stabilization of an injured pelvic ring, due to some disadvantages such as high complication rate, nerve damage, and difficulties of patient's mobility and comfort, there has recently been increased searching for alternative methods for stabilization of the pelvic ring. Pubic symphysis zone freely moves in pelvic models. This study aims to evaluate the biomechanical stability of anterior pelvic bridge plating and compare it with supraacetabular external fixators in an untreated unstable pelvic fracture model. Samples were loaded statically with 2-mm/min loading rate in single leg standing position. Maximum load was 2.3 kN. When loading the samples, photographs were taken continuously. Stiffness values were calculated from the load displacement curves. Some reference parameters were described and were measured from unloaded and 2.3-kN-loaded photographs of the test. The mean stiffness values were 491.14 ± 52.22, 478.55 ± 41.44, and 470.25 ± 44.51 N/mm for anterior pelvic bridge plating group, supraacetabular external fixator group, and Control group, respectively. According to the measured parameters from photographs, the mean displacement at the pubic symphysis was 4.7 ± 0.32, 15.8 ± 2.01, and 18.2 ± 0.47 mm for anterior pelvic bridge plating, supraacetabular external fixator, and Control group, respectively. The highest displacement in the pubic symphysis was found in Control group, and minimum displacement was observed in anterior pelvic bridge plating group. When the perpendicular distance between the right and left lower end of ischium was examined, it was observed that displacement was minimum in anterior pelvic bridge plating group compared to other two groups, regarding to the high stability of pubic symphysis. In conclusion, this study revealed superiority of anterior subcutaneous plate fixation with biomechanical results.

Surgical considerations with the operative fixation of unstable paediatric pelvic ring injuries.

The operative treatment of unstable pelvic injuries in paediatrics is not frequently indicated. The detailed modes of pelvic ring failure, surgical techniques, fixation choices, and peri-operative difficulties are not well reported. From September 2010 to March 2016, 62 paediatric patients were admitted to an academic level I trauma center with the diagnosis of pelvic ring injury. Of them, 29 (17 males and 12 females) had operative fixation of unstable pelvic injuries. Their average age was 11.7 ± 4.4years. There were six Tile's B injuries and 23 type C injuries. The commonest modes of pelvic ring failure were pubic rami fractures anteriorly and ligamentous sacroiliac joint injuries posteriorly. The iliac apophysis was avulsed in nine patients. Supra-acetabular external fixators were frequently used for anterior fixation while iliosacral IS screws and lateral compression LC screws were commonly used posteriorly. Difficulties were encountered with open reduction and repair of avulsed iliac apophyses in two patients. The IS screws pierced the soft iliac wing in three patients. In two patients with open triradiate cartilage, the purchase of retrograde LC screws was weak due the small sized crescent fragment. The iliac apophysis needs to be repaired following reduction of the displaced hemipelvis. Anterior supra-acetabular external fixation is a good choice in paediatrics even with pubic symphysis diatasis as the pathology is commonly a pubic apophysis avulsion. IS screws might be inserted through plates to prevent piercing the soft iliac wing. Retrograde LC screws should be avoided in young children.

Supra-acetabular fixation and sacroiliac screws for treating unstable pelvic ring injuries: preliminary results from 20 patients

ObjectiveTo analyze the treatment results from 20 patients who underwent an alternative osteosynthesis method as definitive treatment for pelvic ring fractures. MethodsA retrospective analysis was conducted on a series of 20 patients with pelvic ring fractures (Tile type C) and a high risk of postoperative infection, who were treated at Santa Casa de Misericórdia de São Paulo between August 2004 and December 2012. The patients underwent percutaneous supra-acetabular external fixation in association with cannulated 7.0mm iliosacral screws. ResultsThe patients’ mean age was 40 years (range 22–77 years) and the mean length of follow-up was 18.5 months (range 3–69 months). At the end of the treatment, ten patients (50%) were classified as having good results, nine patients (45%) had fair results and one patient (5%) did not have any improvement. Six patients presented complications, and paresthesia of the lateral femoral cutaneous nerve was the most frequent of these (two patients). ConclusionSupra-acetabular external fixation in association with iliosacral percutaneous osteosynthesis is a good definitive treatment method for patients with a high risk of postoperative infection.

The role of angio-embolization in the acute treatment concept of severe pelvic ring injuries

BackgroundIn recent years a wide variety of strategies to treat the haemodynamically unstable patient with pelvic ring fractures have been proposed. This study evaluates our institutional management of patients with severe pelvic fractures and analyses their outcomes. MethodsRetrospective review of all severely injured trauma patients with pelvic ring injuries admitted to a level I trauma centre from 2007 to 2012. Patient records were documented prospectively in a trauma database and evaluation was performed by SPSS. ResultsDuring the study period, a total of 173 patients with pelvic ring fractures were admitted and formed the basis of this study. Overall, 46% of the patients had suffered a type A fracture, 25% a type B fracture and the remaining 29% a type C pelvic ring fracture. Surgical treatment was required in 21% of the patients (pelvic C-clamp, n = 6; supra-acetabular external fixator, n = 32; pelvic packing, n = 12; definitive plate osteosynthesis of the pubis symphysis, n = 6). Angio-embolization was performed in 16 patients (9%); in 8 patients it was the only specific treatment for the pelvic injury on day 0 and in 8 patients it was performed immediately post-operatively. The overall mortality rate was 12.7% (n = 22), with the type C pelvic fractures having the highest mortality (30.0%). Four patients died immediately after admission in the shock room. ConclusionsAngiographic embolization as a first-line treatment was only performed in haemodynamically stable patients or in patients responding to fluid resuscitation with the finding of an arterial blush in the CT scan. In haemodynamically unstable patients, pre-peritoneal pelvic packing in combination with mechanical pelvic stabilization was immediately carried out, followed by angio-embolization post-operatively if signs of persistent bleeding remained present.

Internal anterior fixators for pelvic ring injuries: Do monaxial pedicle screws provide more stiffness than polyaxial pedicle screws?

ObjectivesLittle is known about the mechanical properties of internal anterior fixators (known as INFIX), which have been proposed as subcutaneous alternatives to traditional anterior external fixators for pelvic ring disruptions. We hypothesised that INFIX has superior biomechanical performance compared with traditional external fixators because the distance from the bar to the bone is reduced. MethodsUsing a commercially available synthetic bone model, 15 unstable pelvic ring injuries were simulated by excising the pubic bone through the bilateral superior and inferior rami anteriorly and the sacrum through the bilateral sacral foramen posteriorly. Three test groups were established: (1) traditional supra-acetabular external fixation, (2) INFIX with polyaxial screws, (3) INFIX with monaxial screws. Load was applied, simulating lateral compression force. Outcome measure was construct stiffness. ResultsThe traditional external fixator constructs had an average stiffness of 6.21N/mm±0.40standard deviation (SD). INFIX with monaxial screws was 23% stiffer than the traditional external fixator (mean stiffness, 7.66N/mm±0.86SD; p=.01). INFIX with polyaxial screws was 26% less stiff than INFIX with monaxial screws (mean stiffness, 5.69N/mm±1.24SD; p=.05). No significant difference was noted between polyaxial INFIX and external fixators (mean stiffness, 6.21N/mm±0.40SD; p=.65). ConclusionsThe performance of INFIX depends on the type of screw used, with monaxial screws providing significantly more stiffness than polyaxial screws. Despite the mechanical advantage of being closer to the bone, polyaxial INFIX was not stiffer than traditional external fixation.

When do anterior external or internal fixators provide additional stability in an unstable (Tile C) pelvic fracture? A biomechanical study

This study aimed at evaluating the additional stability that is provided by anterior external and internal fixators in an unstable pelvic fracture model (OTA 61-C). An unstable pelvic fracture (OTA 61-C) was created in 27 synthetic pelves by making a 5-mm gap through the sacral foramina (posterior injury) and an ipsilateral pubic rami fracture (anterior injury). The posterior injury was fixed with either a single iliosacral (IS) screw, a single trans-iliac, trans-sacral (TS) screw, or two iliosacral screws (S1S2). Two anterior fixation techniques were utilized: external fixation (Ex-Fix) and supra-acetabular external fixation and internal fixation (In-Fix); supra-acetabular pedicle screws connected with a single subcutaneous spinal rod. The specimens were tested using a nondestructive single-leg stance model. Peak-to-peak (P2P) displacement and rotation and conditioning displacement (CD) were calculated. The Ex-Fix group failed in 83.3 % of specimens with concomitant single-level posterior fixation (Total: 15/18-7 of 9 IS fixation, 8 of 9 TS fixation), and 0 % (0/9) of specimens with concomitant two-level (S1S2) posterior fixation. All specimens with the In-Fix survived testing except for two specimens treated with In-Fix combined with IS fixation. Trans-sacral fixation had higher pubic rotation and greater sacral and pubic displacement than S1S2 (p < 0.05). Rotation of the pubis and sacrum was not different between In-Fix constructs combined with single-level IS and TS fixation. In this model of an unstable pelvic fracture (OTA 61-C), anterior fixation with an In-Fix was biomechanically superior to an anterior Ex-Fix in the setting of single-level posterior fixation. There was no biomechanical difference between the In-Fix and Ex-Fix when each was combined with two levels of posterior sacral fixation.

Can a Modified Anterior External Fixator Provide Posterior Compression of AP Compression Type III Pelvic Injuries?

Current anterior fixators can close a disrupted anterior pelvic ring. However, these anterior constructs cannot create posterior compressive forces across the sacroiliac joint. We explored whether a modified fixator could create such forces. We determined whether (1) an anterior external fixator with a second anterior articulation (X-frame) would provide posterior pelvic compression and (2) full pin insertion would deliver higher posterior compressive forces than half pin insertion. We simulated AP compression Type III instability with plastic pelvis models and tested the following conditions: (1) single-pin supraacetabular external fixator (SAEF) using half pin insertion (60 mm); (2) SAEF using full pin insertion (120 mm); (3) modified fixator with X-frame using half pin insertion; (4) modified fixator using full pin insertion; and (5) C-clamp. Standardized fracture compression in the anterior and posterior compartment was performed as in previous studies by Gardner. A force-sensitive sensor was placed in the symphysis and posterior pelvic ring before fracture reduction and the fractures were reduced. The symphyseal and sacroiliac compression loads of each application were measured. The SAEF exerted mean compressions of 13 N and 14 N to the posterior pelvic ring using half and full pin insertions, respectively. The modified fixator had mean posterior compressions of 174 N and 222 N with half and full pin insertions, respectively. C-clamp application exerted a mean posterior load of 407 N. Posterior compression on the pelvis was improved using an X-frame as an anterior fixation device in a synthetic pelvic fracture model. This additive device may improve the initial anterior and posterior stability in the acute management of unstable and life-threatening pelvic ring injuries.

Supracetabular external fixation in treating pelvic fractures associated with injuries of abdominal organs

Objective To evaluate the technique and clinical outcomes of supra-acetabular external fixation in treating pelvic fractures associated with injuries of abdominal organs.Methods There were 17 cases of pelvic fractures associated with injuries of abdominal organs.Nine were males and 8 were females,with the average age of 42 years (range,21-75 years).The injury was caused by traffic accident in 9 cases,fall-down from height in 4,and crush by heavy objects in 6.According to Tile classification of pelvic fractures,7 were type B1,3 were type B2,2 were type B3,4 were type C1 and 1 was type C2.Fifteen cases suffered with hemorrhagic shock,2 with perineal injury and 12 with fractures of the limbs.All patients were treated with supra-acetabular external fixation and the outcomes were evaluated by Cole's clinical scoring,Matta and Tornetta's radiographic standards.Results All 17 cases were followed up with the mean period of 6.5 months (range,2-18 months).The average time of operation was 15 min (range,9-25 min).The mean blood loss was 17 ml (range,5-25 ml).All fractures healed and the mean healing period was 9.2 weeks (range,8-12 weeks).Three had transient palsy of lateral femoral cutaneous nerve.Five had soft tissue infection while the bony structures were not involved.According to Cole's scoring for pelvic fractures,15 cases were excellent,1 case was good and 1 case was fair,with the good-excellent rate of 94.12％.According to Matta and Tornetta's standards of fracture reduction,12 were excellent,3 were good and 2 were fair,with the good-excellent rate of 88.24％.Conclusion Supra-acetabular external fixation is a minimal invasive and convenient method for treating pelvic fractures with abdominal organs injury which is mechanically stronger than traditional external fixation via iliac crest. Key words: Pelvis; Fractures, bone; External fixators

Supra‐acetabular external fixation for pelvic fractures: A digital anatomical study

Supra-acetabular external fixation is an important tool for pelvic fractures. Understanding the anatomical characteristics of anterior inferior iliac spine (AIIS) is crucial for the operation. Here, we analyzed the morphology of AIIS and adjacent structures via a digital measurement mode. One hundred and twenty normal pelvic computed tomography (CT) scans were converted into three-dimensional digital models and their parameters were measured by Geomagics software. We obtained the values of 13 important AIIS anatomical characteristics, which were the perpendicular distance of the anterior superior iliac spine(ASIS) and AIIS (PDASIS-AIIS), the perpendicular distance between the AIIS and superior pubic tubercle (PDAIIS-PT), the distance between the AIIS and anterior median line (HDAIIS-ML), the angle of the pin tract line and the horizontal plane (AHOR), the transverse diameter of AIIS (TD), and the minimum diameter of the pin tract plane (DMIN), etc. Among them, six parameters showed significant difference between male and female (PDASIS-AIIS: P =0.040, PDAIIS-PT: P = 0.001, HDAIIS-ML: P = 0.019, AHOR: P = 0.021, TD: P < 0.001, and DMIN: P = 0.003, respectively). These results provided references in locating pinning site for a safer and more accurate supra-acetabular external fixation and also suggested that gender difference should be considered during the surgery.