Bleeding occurring in the vicinity of unstable pelvic ring fractures may be difficult to control. It can be so profuse that the patient’s life is in grave danger. In these cases, the pelvis must be stabilised immediately. The urinary tract is also at risk due to its proximity to the site of the injury. Older patients frequently suffer so-called “stable fractures” (more than 50% of pelvic fractures) as a result of a fall (low-energy trauma).
The forces involved are:
- Lateral compression
- Anterior-posterior compression
- Vertical shear (along the spinal axis)
- Combined injuries
A distinction must always be made between stable and unstable pelvic fractures. Important:
- The pelvis is stable when the major structures in the posterior pelvic ring are uninjured.
- The pelvis is unstable when bony or ligamentous structures in the anterior and posterior pelvic ring have been injured.
There are various classification systems; ultimately, however, they all distinguish between stable, rotationally unstable and rotationally/vertically unstable.
Stable injuries include fractures or avulsion of the iliac wings, ischium, pubis or coccyx below the articulated joints which do not affect the stability of the pelvic ring. These injuries can often be treated without surgery. The priorities in such cases are pain management and patient mobilisation.Rotational instability exists for example when the anterior parts of the pelvis have been dislocated or the posterior structures displaced. However, the vertical stability of the pelvis is not affected. External rotation of one side of the pelvis is referred to as an open book injury (cf. fig. 5). These fractures are treated conservatively or surgically depending on the extent of the injury.
Combined injuries are the most unstable of all. They are frequently combined with additional injuries to the skeletal system and other body parts. The anterior and posterior structures of the pelvic ring are both affected. Surgery is essential in the case of rotationally and vertically unstable fractures. Depending on the injured patient’s condition, emergency external stabilisation is performed using an external or internal fixator before the definitive treatment is administered (commonly plates or screws).
Left: Computed tomography following avulsion injury of the first sacral vertebrum. Right: Postoperative x-ray following minimally invasive stabilisation using long screws inserted through small incisions in the skin.