Partially unstable pelvic ring injury: bilateral anterior pubic root fractures and a disruption of the left sacroiliac joint—61-B2.2

10.1055/b-0034-87623

Partially unstable pelvic ring injury: bilateral anterior pubic root fractures and a disruption of the left sacroiliac joint—61-B2.2

Peter A Cole, Brian W Hill

Case description

A 36-year-old man injured his pelvis after he was ejected from a motor vehicle. The patient was initially hemodynamically unstable but subsequently resuscitated. After hemodynamic stabilization the patient was found to have a left sacroiliac disruption and multiple parasymphyseal and ramus fractures. This variant is commonly referred to as an LCII (lateral compression type II) injury. The fracture can be appreciated on the “inlet” and “outlet” 3-D CT reconstructions ( Fig 14.2-1 ).

a–b Inlet (a) and outlet (b) 3-D reconstruction of lateral compression (LC-II) pelvic ring injury.

Indication for MIPO

Operative management of this fracture was indicated due to the relative instability of the pelvic ring. Stabilization allows for early mobilization, earlier weight bearing and promotes quicker resolution of pain [ 1]. Initially, closed reduction of the left sacroiliac joint was performed with a partially threaded cannulated 7.3 mm screw with a washer. This step reduced the sacroiliac joint and reduced the pelvis.

A push-pull test on the iliac wings then demonstrated residual instability by virtue of excessive motion through the anterior fractures 1 cm of displacement [ 2]. This could be appreciated on C-arm films. Whereas previously an external fixator would have been applied to the pelvis at this juncture [ 3], the author now believes that an internal fixator (a “pelvic bridge”) is the method of choice based on early published clinical experiences [ 4– 11].

Anterior fixation is advantageous for complex rami or parasymphyseal fractures. The internal fixator provides several advantages over external fixation. There is less chance of infection due to a sealed integument. Pin-site infections are common to the external fixator technique [ 12]. The internal fixator renders greater stability to the pelvis because the fixation is applied directly to bone. Unlike external fixation, the internal fixator does not obstruct general surgeons who may need to access the abdomen, nor is it uncomfortable for the patient with regard to sitting or dressing.

There are numerous advantages of the method described here, sometimes referred to as the pelvic less invasive stabilization system (P LISS) or anterior pelvic internal fixator (APIF), over other anterior internal fixators which go from the anterior inferior iliac spine on one side to the other:

• There is no chance of irritation or injury to the lateral femoral cutaneous nerve, which occurs in approximately one third of reported cases when the AIIS is used for purchase with pedicle screws [ 7, 9].
There is improved stability with fixation into the symphysis. The third point of fixation completes the stability of the whole ring.
There is stabilization of the parasymphyseal region which is an origin for muscles. The contracting external oblique, rectus, and adductors, for example, originate or insert into this region allowing residual instability with techniques which do not allow for purchase into the pubis.
The uninjured side does not have to be violated when there is a unilateral lesion, which is commonly the case when isolated inferior and superior ramus fractures occur.
The landmarks are easily palpable, more accessible, and familiar to surgeons.
This internal fixator concept can be achieved both with pedicle screws and spinal rods, or with locking plates and screws.

Preoperative planning

The preoperative plan requires understanding of 3-D pelvic anatomy. The surgeon must appreciate pelvic rotational displacement (internal-external or flexion-extension, as well as cephalad-caudad and anterior-posterior displacement) on the inlet and outlet x-rays.

It is essential to first obtain a reduction of the posterior pelvis, and then address the posterior pelvic fixation before executing the anterior pelvic MIO fixation. The posterior lesion is prioritized, addressed definitively (whether with ORIF or percutaneously), and then the decision to address the anterior fractures and residual instability follows ( Fig 14.2-2 ).

If there are unilateral rami fractures, then a unilateral internal pelvic fixator can be applied subcutaneously between the anterior crest and the contralateral pubis. The authors prefer contouring a 14–16 hole locking reconstruction plate 3.5 on a plastic bone mold prior to entering the operating room. Alternatively, a spinal rod can be contoured for the same pathway. Care must be taken to contour the implant so that it creates no posterior compression on the abdominal wall or inguinal region.