Stabilization of a Type B1.1 Injury in a Morbidly Obese Patient Using an Internal Fixator in a Minimally Invasive Technique: A Case Report

A novel minimally invasive and press-fit method for symphysiodesis - a biomechanical analysis

PURPOSE

Does the cylindrical shaped bone block allow a stable construct for the arthrodesis of the pubic symphysis compared to a rectangular shaped bone block. The cylindrical shaped bone block stabilized by a 3.5 symphyseal plate is inferior to the stabilization with an internal fixator.

METHODS

This study analyzed the arthrodesis of the pubic symphysis on 24 synthetic pelvises, using a rectangular shaped bone block (control group) or a cylindrical shaped bone block, stabilized with a symphysis locking plate (n = 8) as the standard clinical procedure. Additionally we analyzed the stability using an internal fixator.

RESULTS

This study showed that utilizing a cylindrical shaped synthetic bone graft results in a significant higher contact area and compression force compared to the classical rectangular shaped graft. Furthermore, the stabilization with an internal fixator had the tendency for increases of compression force and contact area, yet without a statistical significance, when compared to the plate fixation.

CONCLUSION

The novel method of cylindrical symphysis resection and cylindrical bone block implantation allowed an increased biomechanical stability compared to using a classical rectangular bone graft, also resulting in higher contact area. Moreover, this technique would also allow a minimally invasive approach for this purpose, which in turn could preserve perisymphyseal ligaments, thereby improving healing in a clinical context.

Symphyseal plating for pelvic fracture in a morbidly obese patient: operative challenges and innovation of a novel 'wire-ramp plate-sliding method'

We are describing a case report of a morbidly obese patient (body mass index 41) in his mid-40s with Young and Burgess Anteroposterior Compression type II injury (AO Foundation/Orthopaedic Trauma Association type B1.2) managed by symphyseal plating. Morbid obesity made working at a depth very difficult; hence, we adopted a novel 'wire-ramp plate-sliding method'. In this method, two strong sturdy K-wires inserted through the medial-most plate holes into the pubis acted as a ramp over which the plate was pushed/slid distally. During this manoeuvre, the K-wires passing through the plate holes were used as a reduction tool. The patient also had a wedge fracture of the distal femoral shaft which was managed by retrograde femoral nailing. At 1-year follow-up, the pelvic continuity is maintained and the fracture has united. The patient is able to do full weight-bearing and is back to his normal life.

Development and preclinical evaluation of a cable-clamp fixation device for a disrupted pubic symphysis

BACKGROUND

Traumatic separation of the pubic symphysis can destabilize the pelvis and require surgical fixation to reduce symphyseal gapping. The traditional approach involves open reduction and the implantation of a steel symphyseal plate (SP) on the pubic bone to hold the reposition. Despite its widespread use, SP-fixation is often associated with implant failure caused by screw loosening or breakage.

METHODS

To address the need for a more reliable surgical intervention, we developed and tested two titanium cable-clamp implants. The cable served as tensioning device while the clamp secured the cable to the bone. The first implant design included a steel cable anterior to the pubic symphysis to simplify its placement outside the pelvis, and the second design included a cable encircling the pubic symphysis to stabilize the anterior pelvic ring. Using highly reproducible synthetic bone models and a limited number of cadaver specimens, we performed a comprehensive biomechanical study of implant stability and evaluated surgical feasibility.

RESULTS

We were able to demonstrate that the cable-clamp implants provide stability equivalent to that of a traditional SP-fixation but without the same risks of implant failure. We also provide detailed ex vivo evaluations of the safety and feasibility of a trans-obturator surgical approach required for those kind of fixation.

CONCLUSION

We propose that the developed cable-clamp fixation devices may be of clinical value in treating pubic symphysis separation.

Trans-obturator cable fixation of open book pelvic injuries

Operative treatment of ruptured pubic symphysis by plating is often accompanied by complications. Trans-obturator cable fixation might be a more reliable technique; however, have not yet been tested for stabilization of ruptured pubic symphysis. This study compares symphyseal trans-obturator cable fixation versus plating through biomechanical testing and evaluates safety in a cadaver experiment. APC type II injuries were generated in synthetic pelvic models and subsequently separated into three different groups. The anterior pelvic ring was fixed using a four-hole steel plate in Group A, a stainless steel cable in Group B, and a titan band in Group C. Biomechanical testing was conducted by a single-leg-stance model using a material testing machine under physiological load levels. A cadaver study was carried out to analyze the trans-obturator surgical approach. Peak-to-peak displacement, total displacement, plastic deformation and stiffness revealed a tendency for higher stability for trans-obturator cable/band fixation but no statistical difference to plating was detected. The cadaver study revealed a safe zone for cable passage with sufficient distance to the obturator canal. Trans-obturator cable fixation has the potential to become an alternative for symphyseal fixation with less complications.

A novel internal fixation method for open book injuries of the pubic symphysis- A biomechanical analysis

BACKGROUND

Pelvic fractures in adults are common injuries and account for up to 3.64% of all fractures. Usually, the treatment of open book injuries (Types B1.1 and B1.2 AO-Classification) is open reduction and plate stabilization using dynamic compression plates, with or without interlocking screws. These implants seem to enhance the outcome of such injuries, but also variety of complications occurs. To reduce complications and achieve appropriate reduction and stabilization, this study compared established stabilization techniques to a novel minimally invasive internal fixation method using an internal fixator system that is already being utilized for spinal fractures.

METHODS

This study was performed on 32 composite pelvises in a bilateral stance biomechanical model. The pelvises were variously stabilized with an internal fixator, a 4.5 mm dynamic compression plate and a 3.5 mm symphyseal locking dynamic compression plate. The contact area and loading forces were assessed by a sensor film inside the symphyseal gap.

FINDINGS

This study showed significantly greater reduction and loading capabilities of the internal fixator compared to the other implants (p < 0.05). There was also significantly greater contact area with the use of an internal fixator compared to the other implants (p < 0.05). The 3.5 mm interlocking plate showed significantly greater contact area compared to the 4.5 mm plate (p < 0.05).

INTERPRETATION

The internal fixator that is already proven in spinal surgery is biomechanically superior to conventional implants used in pelvic surgery. The contact area analysis furthermore showed a more physiological loading pattern, which can improve ligamentous healing in a clinical context.