Locked Versus Standard Unlocked Plating of the Pubic Symphysis

Department of Orthopaedic Surgery, Saint Louis University School of Medicine, St Louis, MO 63110, USA.
Journal of orthopaedic trauma (Impact Factor: 1.8). 12/2011; 26(7):402-6. DOI: 10.1097/BOT.0b013e31822c83bd
Source: PubMed


Although locked plating has been shown to have advantages for diaphyseal and metaphyseal fracture fixation, its benefits for pubic symphyseal disruption have not been established. With traditional plate fixation of the disrupted pubic symphysis, normal physiological symphyseal pelvic motion eventually results in plate breakage, screw breakage, and loosening of screws. A concern exists that common modes of locked plate construct failure could result in abrupt and complete loss of symphyseal fixation. The purposes of this study were to determine, using an open-book pelvic injury model, whether locked plating of the pubic symphysis 1) offers any advantage over standard unlocked plating; and 2) results in a potential increased risk of abrupt fixation failure.
Twelve osteopenic cadaver pelvic specimens were acquired and dual-energy x-ray absorptiometry scans were obtained to ensure uniformity of the specimens' bone density. Sacrospinous, sacrotuberous, and anterior sacroiliac ligaments were released and the symphysis pubis was transected to simulate a partially stable open book (AO/Orthopaedic Trauma Association 61-B3.1) injury. Using a six-hole 3.5-mm plate specifically designed for the symphysis pubis with the capability of fixation in locked or unlocked mode, six pelvises were fixed with locked screws and six pelvises were fixed standard unlocked bicortical screws. There was no significant difference between these 2 groups with regard to bone density (P = 0.47). Two equally osteopenic pelvic specimens from each fixation group were selected for the purpose of obtaining failure data and determining an acceptable load for trialing. Both specimens failed at 1985 N. The remaining 10 pelvises were then mounted on a materials testing apparatus using the bilateral stance model as described by Tile. In accordance with the failure data, each pelvis was stressed at 440 N for a total of one million cycles (equivalent to 6.5 months of daily walking) or until fixation failure.
All pelvic specimens in both fixation groups completed one million cycles without plate or screw failure. However, diastasis of the initial pubic symphysis reduction was found in all pelvises (mean, 2.45 mm; range, 1.5-4.0 mm) regardless of fixation method. This loss of reduction was not significantly different between the 2 fixation groups (P = 0.914).
No abrupt failures occurred in either plating group. Consequently, any fear of catastrophic (ie, abrupt and complete) failure of locked symphyseal plates appears to be unfounded for open-book injuries treated in patients with low bone density. However, minor loss of the symphyseal reduction was evident in all pelvises regardless of the fixation method. Therefore, locked plating of the pubic symphysis does not appear to offer any advantage over the standard unlocked technique for an AO/Orthopaedic Trauma Association 61-B3.1 partially stable open-book pelvic injury pattern in osteopenic bone.

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    ABSTRACT: 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.
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    ABSTRACT: Once the patient with pelvic fracture is resuscitated and stabilized, definitive surgical management and anatomic restoration of the pelvic ring become the goal. Understanding injury pattern by stress examination with the patient under anesthesia helps elucidate the instability. Early fixation of the unstable pelvis is important for mobilization, pain control, and prevention of chronic instability or deformity. Current pelvic fracture management employs a substantial amount of percutaneous reduction and fixation, with less emphasis placed on pelvic reconstruction proceeding from posterior to anterior, and most reduction and fixation of unstable pelvic fractures done with the patient supine. Compared with control subjects with acetabular fracture or pelvic fracture alone, patients with combined injury have a significantly higher Injury Severity Score, lower systolic blood pressure, and higher mortality rates; they are also transfused more packed red blood cells. Even with anatomic restoration of the pelvis, long-term outcomes after severe pelvic trauma are below population norms. The most common chronic problems relate to sexual dysfunction and pain. Regardless of fracture type, neurologic injury is a universal harbinger of poor outcome.
    No preview · Article · Aug 2013 · The Journal of the American Academy of Orthopaedic Surgeons
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    ABSTRACT: The benefits of locked plating for pubic symphyseal disruption have not been established. The purpose of this biomechanical study was to determine whether locked plating offers any advantage over conventional unlocked plating of the pubic symphysis in the vertically unstable, Type-C pelvic injury. In each of eight embalmed cadaver pelvis specimens, sectioning of the pubic symphysis in conjunction with a unilateral release of the sacroiliac, sacrospinous, and sacrotuberous ligaments and pelvic floor was performed to simulate a vertically unstable Type-C (Orthopaedic Trauma Association 61-C1.2) pelvic injury. The disrupted SI joint was then reduced and fixed using two 6.5mm cannulated screws inserted into the S1 body. Using a six-hole 3.5mm plate specifically designed for the symphysis pubis having both locked and unlocked capability, four pelvises were fixed with locked screws and four pelvises were fixed with standard unlocked bicortical screws. Both groups were similar based on a dual-emission X-ray absorptiometry evaluation (P=0.69). Each pelvis was then mounted on a servohydraulic materials-testing apparatus using a bilateral stance model to mainly stress the symphyseal fixation and was cycled up to 1 million cycles or failure, whichever occurred first. Five specimens experienced failure at the jig mounting/S1 vertebral body interface, occurring between 360,000 and 715,000 cycles. Frank failure of the anterior or posterior instrumentation did not occur. However, end-trialing diastasis of the initial pubic symphysis reduction was found in all pelvises. There were no differences between the groups with respect to this loss of symphyseal reduction (P=0.69) or average cycles to failure (P=1.0). Pubic symphyseal locked plating does not appear to offer any advantage over standard unlocked plating for a Type-C (OTA 61-C1.2) pelvic ring injury.
    Preview · Article · Nov 2013 · Injury
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