Biomechanical characteristics of fixation methods for floating pubic symphysis.

BACKGROUND: Floating pubic symphysis (FPS) is a relatively rare injury caused by high-energy mechanisms. There are several fixation methods used to treat FPS, including external fixation, subcutaneous fixation, internal fixation, and percutaneous cannulated screw fixation. To choose the appropriate fixation, it is necessary to study the biomechanical performance of these different methods. The goal of this study was to compare the biomechanical characteristics of six methods by finite element analysis. METHODS: A three-dimensional finite element model of FPS was simulated. Six methods were used in the FPS model, including external fixation (Ext), subcutaneous rod fixation (Sub-rod), subcutaneous plate fixation (Sub-plate), superior pectineal plate fixation (Int-sup), infrapectineal plate fixation (Int-ifa), and cannulated screw fixation (Int-scr). Compressive and rotational loads were then applied in all models. Biomechanical characteristics that were recorded and analyzed included construct stiffness, micromotion of the fracture gaps, von Mises stress, and stress distribution. RESULTS: The construct stiffness of the anterior pelvic ring was decreased dramatically when FPS occurred. Compressive stiffness was restored by the three internal fixation and Sub-rod methods. Unfortunately, rotational stiffness was not restored satisfactorily by the six methods. For micromotion of the fracture gaps, the displacement was reduced significantly by the Int-sup and Int-ifa methods under compression. The internal fixation methods and Sub-plate method performed well under rotation. The maximum von Mises stress of the implants was not large. For the plate-screw system, the maximum von Mises stress occurred over the region of the fracture and plate-screw joints. The maximum von Mises stress appeared on the rod-screw and screw-bone interfaces for the rod-screw system. CONCLUSIONS: The present study showed the biomechanical advantages of internal fixation methods for FPS from a finite element view. Superior stabilization of the anterior pelvic ring and fracture gaps was obtained by internal fixation. Subcutaneous fixation had satisfactory outcomes as well. Sub-rod fixation offered good anti-compression, while the Sub-plate fixation provided favorable anti-rotational capacity.

Management of pubic symphysis diastasis with locking plates: a report of 11 cases.

INTRODUCTION: The optimal method of fixation of symphyseal disruptions in pelvic ring injuries and post-operative rehabilitation is still debated. Options include two-hole, multi-hole and multiplanar plates. Post-operative rehabilitation can range from non-weight bearing bilaterally to full weight-bearing with crutches. Locking symphyseal plates have recently been introduced. There is a paucity of literature evaluating their use in such injuries. We present the first clinical case series of symphyseal diastasis managed with locking plates. METHODS: A retrospective analysis of a single centre case series between August 2008 and December 2011 was conducted. A total of 11 patients; 2 females and 9 males with a mean age of 42 years were included. The mean radiological follow up was 27 weeks. Radiological failure and need for revision were evaluated. RESULTS: 4 patients sustained their injury as a result of a motorcycle accident, 3 patients following a car accident, 2 fell from a height and 2 had crush injuries. 9 patients had other concomitant injuries. The mechanism of injury was classified as anterior-posterior compression injury in 6 patients, vertical shear in 4 patients and combined mechanism in 1 patient. 6 patients required posterior pelvic fixation. Patients were mobilised fully or partially weight bearing. One patient had a significant radiological failure. All patients were asymptomatic at last follow-up and none required revision surgery. CONCLUSION: Our series represents the first published clinical series of patients with symphyseal diastasis managed with locking plates. We have found the use of locking plates across the pubic symphysis to be safe with low complication rates despite early weight bearing.

Locking and nonlocking plate fixation pubic symphysis diastasis management.

We evaluated the stability of locking and nonlocking plate fixation of the pubic symphysis in a cadaveric model of an unstable pelvic injury. Five fresh cadaver pelves--intact and with an unfixed simulated Tile B injury--were tested under compressive load simulating a 2-legged stance. On each pelvis, 3 pubic symphysis fixation constructs were tested: a 4-hole unicortical locking plate, a 4-hole bicortical locking plate, and a 4-hole bicortical compression plate. There were no significant differences in displacement among the 3 fixation methods tested on Tile B pelvic simulations. Symphysis pubis fixation alone reduced the anterior superior pubic symphysis mean gap displacement by 95% and the anterior inferior pubic symphysis by 78%, compared with the noninstrumented Tile B injury. There is no evidence that anteriorly placed locking constructs confer an advantage, in terms of pubic symphysis stability, over standard anterior compression plates for Tile B injuries.

Biomechanical analysis of a transiliac internal fixator.

PURPOSE: We evaluated the biomechanical characteristics of the transiliac internal fixator (TIFI) as compared to two well-established methods of internal posterior pelvic ring fixation. METHODS: Six freshly frozen human pelves were used for simulated single-leg stance loading of an AO type C injury model (pubic symphysis diastasis and unilateral sacroiliac joint disruption). The symphysis rupture was stabilized with a dynamic compression plate. Afterwards the three internal stabilization systems (TIFI, iliosacral screws and ventral plate osteosynthesis) were analysed. Fragment movement was measured in a contact-free manner with a stereophotometric infrared system. RESULTS: No significant differences in the three-dimensional deformation tolerated by the TIFI as compared to the other internal fixation systems were found. CONCLUSIONS: The transiliac internal fixator provides the same biomechanical stability as the other reference implants tested. We suggest the use of this device as a suitable alternative to the other implants.

Fractura de Pelvis. Una fractura compleja / Fracture of the Pelvis. A complex fracture

Se presenta el caso de un paciente joven con fractura de pelvis por accidente de tráfico. La fractura se presentó con una clínica abdominal y ECO FAST positivo con respuesta transitoria a la fluidoterapia. La biomecánica del accidente permitió sospechar la existencia de lesiones no observables con la proyección radiológica básica. El estudio de imagen diferido en 3D reveló la existencia de lesiones no visibles en la radiografía inicial, pero sospechadas por los antecedentes traumáticos. El presente caso nos permite repasar la sistemática de actuación ante un paciente politraumatizado (A-B-C-D-E), así como destacar la importancia que las fracturas de pelvis pueden tener en estos pacientes, ya que son causa de shock por pérdida de sangre masiva a nivel interno. Los pacientes con sospecha de fractura pélvica deben ser movilizados en bloque, manteniendo la alineación del eje cabeza-cuello-tronco, y una vez comprobada la estabilidad se debe proceder a la inmovilización de la pelvis, bien mediante un fajado pélvico o bien mediante dispositivos específicos para ello (AU)

We present a case of a young patient with a fractured pelvis due to a traffic accident. The patient had a positive FAST scan and transient response to fluid therapy. Due the biomechanics of the accident we suspected the existence of lesions that could not be observed with basic X-ray procedures. A 3-D image study revealed the lesions that were not visible by X-ray but suspected due to the nature of the trauma. This case enables us to review the A-B-C-D-E approach to the assessment of a polytraumatised patient and to emphasis the importance that a fractured pelvis could have for these patients as it is a cause of shock due to massive internal haemorrhage. Patients with a suspected fracture of the pelvis should be moved in block, maintaining the head-neck-trunk in line and once stabilised the pelvis should then be immobilised using a pelvic binder or other specific devices (AU)

Radiological analysis, operative management and functional outcome of open book pelvic lesions: a 13-year cohort study.

UNLABELLED: We present the clinical and radiological outcome of a 13-year cohort study of 38 open book pelvic lesions. All patients were treated in one Level I Trauma centre. In the posterior pelvis, sacro-iliac diastasis was seen in 31 patients, sacral fracture in 7. In all patients with sacro-iliac diastasis, the pubic bone was inferiorly displaced on the primary ap pelvic overview on the side of injury. All but one patient was treated with open reduction and internal fixation of the symphysis pubis. Additional stabilization of the posterior pelvis was done in 9 patients. 32 patients were seen after a median follow up of 84 months. Majeed score and SF-36 questionnaire were used. Functional outcome was excellent with a mean Majeed score of 95.7. Comparing our data with the SF-36 score of the normal German population, the mean value of the 'role-physical' and the 'physical function' categories was significantly lower for patients treated with an open book lesion. There was a tendency towards a better outcome in open book lesions with sacral fracture. There was a tendency towards worse outcome for the patients with additional dorsal stabilization. Male impotence was the single most important lesion of neurological origin which persisted two years after open book lesion. CONCLUSION: Functional outcome after surgical treatment of open book pelvic lesions is good. External rotation and accompanying inferior displacement of the ipsilateral hemipelvis may be a sign of partial lesion of the posterior sacroiliac complex. Identification of patients who need additional posterior stabilization remains difficult.

Lesión anterior de pelvis asociada a una fractura poco habitual del sacro / Anterior pelvic ring injury associated with an unusual sacral fracture

Hombre de 52 años que sufrió un accdente de tráfico mientras conducía una motocicleta. Las radiografías simples de pelvis tomadas a su ingreso evidenciaron una amplia diastasis de la sínfisis púbica, una fractura mediosagital del sacro y otra fractura de la apófisis transversa derecha de la quinta vértebra lumbar. Presentamos el tratamiento utilizado para abordar esta inusual lesión (AU)

A 52-year-old male sustained a road traffic accident riding a motorbike. At his admission, plain radiograph of the pelvis showed wide diastasis of the pubic symphysis, a midsagittal fracture of the sacrum and a fracture of the right transverse process of the fifth lumbar vertebra. We discuss the treatment of this rare injury (AU)

Symphysial pelvic dysfunction.

PURPOSE OF REVIEW: Symphysial pelvic dysfunction is a condition which develops during pregnancy and may lead to significant morbidity affecting quality of life. While postpartum resolution is common, symptoms may persist for many years. The consequences, specifically disabling pain, are even more detrimental on mothers with a young family. This review summarizes current understanding of the condition, including pathogenesis, risk factors and management. RECENT FINDINGS: There is no current international consensus on definition, diagnostic criteria, and treatment protocols for symphysial pelvic dysfunction. Discrepancy between the reported rates of prevalence stems from ambiguity in definition and inclusion criteria in reported studies. The pathogenesis of the condition is still unclear although numerous theories have been proposed. It is likely to be multifactorial in origin with multiple factors both biomechanical and genetic factors playing an important role. There is also a paucity of information in the literature about the best management strategy. SUMMARY: There is an urgent need to standardize terminology and define diagnostic criteria for symphysial pelvic dysfunction in order to improve the management and better understand the pathophysiology of this condition.