Traditionally, unstable anterior pelvic ring injuries have been stabilised with an external fixator or by internal fixation. Recently, a new percutaneous technique of placement of bilateral supraacetabular polyaxial screws and subcutaneous connecting bar to assemble an “internal fixator” has been described.

We present the surgical technique and early clinical results of using this technique in twenty-five consecutive patients with a rotationally unstable pelvic ring injury and no diastasis of the symphysis pubis treated between April 2010 and December 2013. Additional posterior pelvic stabilisation with percutaneous iliosacral screws was used in 23 of these patients. The anterior device was routinely removed after three months.

Radiological evidence of union of the anterior pelvic ring was seen in 24 of 25 patients at a minimum 6 month follow-up. Thirteen patients developed sensory deficits in the lateral femoral cutaneous nerve (five bilateral) and only one fully recovered.

The anterior pelvic internal fixator is a reliable, safe and easy percutaneous technique for the treatment of anterior pelvic ring injuries, facilitating the reduction and stabilisation of rotational displacement. However, lateral femoral cutaneous nerve dysfunction is common. The technique is recommended in cases with bilateral or unilateral pubic rami fractures and no diastasis of the symphysis pubis.

Stable, anatomical fixation of acetabular fractures gives the best chance of a good outcome. We performed a biomechanical study to compare fracture stability and construct stiffness of three methods of fixation of posterior wall acetabular fractures.

Two-dimensional motion analysis was used to measure fracture fragment displacement and the construct stiffness for each fixation method was calculated from the force / displacement data.

Following 2 cyclic loading protocols of 6000 cycles, to a maximum 1.5kN, the mean fracture displacement was 0.154mm for the rim plate model, 0.326mm for the buttress plate and 0.254mm for the spring plate model. Mean maximum displacement was significantly less for the rim plate fixation than the buttress plate (p=0.015) and spring plate fixation (p=0.02).

The rim plate was the stiffest construct 10962N/mm (SD 3351.8), followed by the spring plate model 5637N/mm (SD 832.6) and the buttress plate model 4882N/mm (SD 387.3).

Where possible a rim plate with inter-fragmentary lag screws should be used for isolated posterior wall fracture fixation as this is the most stable and stiffest construct. However, when this method is not possible, spring plate fixation is a safe and superior alternative to a posterior buttress plate method.

Introduction

Pelvic and acetabular injuries are relatively rare and surgical reconstruction usually occurs only in specialist centres. As part of their work up there is a local protocol for radiological investigations including Judet oblique views for acetabular fractures, pelvic inlet and outlet for pelvic ring fractures and urethrograms for sustaining anterior pelvic injury. The aim of this service evaluation was to assess whether patients had these radiological investigations prior to transfer.