1 Introduction top
Before proceeding with definitive repairs, the patient must be fully resuscitated, fully evaluated, and fit for anesthesia and surgery by a prepared team.
Risk of bleeding
B1 injuries disrupt the pelvic floor, and often tear the pelvic venous plexus. Displacement increases the pelvic volume, allowing greater blood loss before any self-tamponade.
Because of initial bleeding, the patient may be hypovolemic or anemic at the time of definitive treatment. Intrapelvic surgery may disturb injured vessels and cause bleeding to restart.
Transfusions and blood salvage should be anticipated.
Lumbo-sacral nerve root injury
Before undertaking definitive treatment of pelvic ring injuries, It is essential to know the functional status of the patient's lumbosacral nerve roots. A careful and detailed examination is necessary, to assess perineal sensation, voluntary anal sphincter contraction, and bulbo-cavernosus reflex. Cystometrography may be helpful to assess bladder neuromotor function.
Neurologic abnormalities should be correlated with anatomic site of injury:
- If a lumbo-sacral nerve deficit is present in extra sacral injuries, further investigation and possible treatment must be considered.
- If a sacral nerve deficit is present with a sacral fracture, the nerves should be decompressed with fracture reduction and/or sacral laminectomy.
Type B1 pelvic ring injuries are unilateral and always involve external rotation of the instable hemipelvis.
This injury is produced by an impact or compressive force oriented sagittaly (anterior/posterior compression (APC).
B1 pelvic ring injuries are partially stable because the posterior pelvic arch disruption is partial, with an intact posterior “hinge”, usually the intact posterior S-I ligament, (B1.1).
Occasionally, the “hinge” is an incomplete sacral alar fracture. (B1.2).
The anterior disruption, which can be quite wide, is almost always through the pubic symphysis.
The width of the disrupted symphysis, as shown by an initial AP x-ray may understate the degree of instability. Stress radiographs may be necessary for accurate assessment of instability.
While some B1 injuries with slight symphyseal diastasis do not need surgery, there is no certain width that separates stable from unstable injuries.
Principle of treatment
Theoretically, due to the intact posterior "hinge", both type B1.1 and B1.2 injuries can be stabilized by reducing and fixing the anterior arch disruption.
However, incomplete sacroiliac ligament disruptions present with a range of instability. This might be recognized by sagittal rotation or displacement on appropriate stress x-rays.
Posterior ring fixation is not necessary for all type B1 pelvic ring injuries. However, posterior fixation should be considered for more severe posterior arch injuries to prevent:
- persistent posterior pain
- post-traumatic arthritis,
- failure of anterior fixation
Specific indications for posterior fixation of B1 injuries remain unclear.
2 Sequence of reduction and fixation top
Reduction of the symphysis is performed first. Because of the intact posterior hinge, this restores alignment of the mobile hemipelvis.
If any posterior stabilization is considered, it should follow the anterior arch repair.
3 Reduction and fixation topenlarge
Plating of the pubic symphysis is indicated for symphysis disruptions associated with pelvic ring instability. Evidence of mechanical instability is confirmed with physical exam and/or stress x-rays.
The required technique for symphyseal repair is:
Partially unstable (B1) SI joints or incomplete sacral alar fractures are widened anteriorly on CT scans. If displacement extends all the way through the posterior part of the SI joint or the sacral fracture, complete posterior arch disruption is likely and internal fixation must be considered.
Percutaneous iliosacral screw fixation is usually the preferred technique.
In the rare case of a B1 sacral fracture, this should be repaired with an IS screw, unless it is displaced or associated with neurological deficit.
If available, the use of intraoperative navigation may be beneficial for iliosacral screw fixation.
4 Check of osteosynthesis topenlarge
Check the completed osteosynthesis with Imaging, and physical exam if there is any question about pelvic stability.
Using inlet and outlet views, with the C-arm, confirm that pelvic deformity has been corrected and that involved sacroiliac joints and pubic symphysis are anatomically reduced.
Unless a C-arm with a large field of view is available, it may be wise to obtain similarly oriented portable x-rays of the entire pelvis, to be certain about overall alignment.
Confirm that reduction of each fracture or joint injury is satisfactory, Make sure that all fixation devices are properly placed, and that each screw is of appropriate length. Multiple views are typically needed, including both axial and perpendicular views for questionable screws. If screws protrude from bone, consider risks to nerves, vessels, and adjacent viscera, especially urethra and bladder after pubic symphysis repair.