Pelvic bony injury requires substantial force, and there are several distinct fracture patterns seen. Today, I’ll briefly review the so called A-P force mechanism and its grading.
The anterior-posterior (A-P) mechanism frequently results in what many call an “open book” pelvis on x-ray evaluation. It most commonly occurs when something heavy rolls over or crushes the pelvis. We see this in patients who have a vehicle roll over their torso, or are crushed by heavy machinery. The force is applied to the sacrum posteriorly and the anterior portions of the iliac crests. This fulcrum effect displaces one or both iliac wings posteriorly. The flexion point is typically the sacro-iliac joint or the sacral wings. The pubic symphysis pulls apart as the iliac wings move away from their anatomic position.
The usual grading system assigns a type subclassification based on the amount of disruption:
Type I – less than 1 inch (2.5cm) of pubic diastasis, or rami are fractured; no significant posterior injury
Type II – more than 1 inch of diastasis; one or both SI joints widened; posterior SI ligament intact; anterior SI, sacrospinous and sacrotuberous ligaments torn
Type III – all anterior and posterior ligaments disrupted
How is this grading system useful? It is generally predictive of hemodynamic instability, resuscitation requirements, and the possibility of concomitant vascular and/or neurologic compromise. However, you can also get a pretty good idea of all of that just looking at the x-ray. But it is helpful in describing the injury to your orthopedic colleagues.
Yesterday, I detailed some pelvic binders commonly available
in the US.
Today, I’ll go through the (little) science there is regarding which are better
There are a number of factors to consider when choosing one
of these products. They are:
Does it work?
Does it hurt or cause skin damage?
Is it easy to use?
How much does it cost?
It’s difficult to determine how well binders work in the live,
clinical setting. But biomechanical studies can serve as a surrogate to try to answer
this question. One such cadaver study was carried out in the Netherlands a
few years ago. They created one of three different fracture types in pelvis
specimens. Special locator wires were placed initially so they could measure bone movement
before and after binder placement. All three of the previously discussed
commercial binders were used.
Here are the factoids:
In fracture patterns that were partially stable or unstable,
all binders successfully closed the pelvic ring.
None of the binders caused adverse displacements of fracture
Pulling force to achieve complete reduction was lowest with
the T-POD (40 Newtons) and highest with the SAM
pelvic sling (120 Newtons).
The SAM sling limits compression to 150 Newtons,
which was more than adequate to close the pelvis.
So what about harm? A healthy volunteer study was used to
test each binder for tissue pressure levels. The 80 volunteers were outfitted
with a pressure sensing mat around their pelvis, and readings were taken with
each binder in place.
Here are the additional factoids:
The tissue damage threshold was assumed to be 9.3 kPa
sustained for more than 2-3 hours based on the 1994 paper cited below.
All binders exceeded the tissue damage threshold at the
greater trochanters and sacrum while lying on a backboard. It was highest with
the Pelvic Binder and lowest with the SAM sling.
Pressures over the trochanters decreased significantly after
transfer to a hospital bed, but the Pelvic Binder pressures remained at the
tissue damage level.
Pressures over the sacrum far exceeded the tissue damage pressure
with all binders on a backboard and it remained at or above this level even
after transfer to a bed. Once again, the Pelvic Binder pressures were higher. The
other splints had similar pressures.
And finally, the price! Although your results may vary due to
your buying power, the SAM sling is about $50-$70, the Pelvic Binder $140, and
the T-POD $125.
Bottom line: The binder that performed the best (equivalent
biomechanical testing, better tissue pressure profile) was the SAM sling. It also happens to be the least expensive, although it takes a little more elbow grease to apply. In my mind, that’s a winning combo.
Plus, it’s narrow, which allows easy access to the abdomen and groins for
procedures. But remember, whichever one you choose, get them off as soon as
possible to avoid skin complications.
Several products for compressing the fractured pelvis are available. They range from free and simple (a sheet), to a bit more complicated and expensive. How to decide which product to use? Today, I’ll discuss the four commonly used products. Tomorrow, I’ll look at the science.
There are three commercial products that are commonly used. First is the Pelvic Binder from the company of the same name (www.pelvicbinder.com). It consists of a relatively wide belt with a tensioning mechanism that attaches to the belt using velcro. One size fits all, so you may have to cut down the belt for smaller patients. Proper tension is gauged by being able to insert two fingers under the binder.
Next is the SAM Pelvic Sling from SAM Medical Products (http://www.sammedical.com). This device is a bit fancier, is slimmer, and the inside is more padded. It uses a belt mechanism to tighten and secure the sling. This mechanism automatically limits the amount of force applied to avoid problems with excessive compression. It comes in three sizes, and the standard size fits 98% of the population, they say.
Finally, there is the T-POD from Pyng Medical (http://www.pyng.com/products/t-podresponder). This one looks similar to the Pelvic Binder in terms of width and tensioning. It is also a cut to fit, one size fits all device. It has a pull tab that uses a pulley system to apply tension. Again, two fingers must be inserted to gauge proper tension.
So those are the choices. Tomorrow, I’ll go over some of the data and pricing so you can make intelligent choices about selecting the right device for you.
The usual thinking is that most unstable trauma patients need a quick trip to the OR to stop the bleeding from something. In the US and Europe, patients with nasty pelvic fractures are no exception, especially those with hemoperitoneum. But many of these patients are bleeding from vessels associated with the pelvic fractures and not so much from associated intra-abdominal injuries. And operative management of pelvic fracture bleeding is far from satisfying, even when using preperitoneal packing.
Well, things are a little different in Japan. In many cases, unstable patients are taken to interventional radiology for angio and possible embolization. Is this prudent, or is it dangerous? A Japanese group decided to critically look at this practice by examining the Japan Trauma Data Bank for answers.
Here are the factoids:
Patients with pelvic fracture and positive FAST were included, who underwent either laparotomy or angioembolization as their first intervention (n=1153). Those with non-salvageable head injury were excluded, as well as patients who underwent another major procedure first (craniotomy, thoracotomy, ortho procedures, etc.). Only 317 patients remained.
In-hospital mortality was the primary outcome of interest
A total of 123 underwent laparotomy first, and 194 went to angio first
A very small number of patients were hypotensive on arrival (81 laparotomy first, 82 angio first)
Half of the patients who were hypotensive on arrival went to angio first (!)
Laparotomy-first patients had a higher crude mortality, but this disappeared when confounders were controlled. This was true in patients who were either normotensive or hypotensive on arrival.
The authors concluded that the initial intervention should be determined by severity of injury, since in-hospital mortality was no different
Bottom line: Whoa! This is a sweeping statement for a study with so few subjects. Yes, it can be very difficult to determine whether initial bleeding is from the pelvis vs a solid organ or mesenteric injury while in the ED. But it is all too easy to fritter away time (and the patient’s blood/life) in the angiography suite. I recommend trying to stabilize your patient as best you can with fluid and/or blood. If you can maintain a “reasonable” blood pressure, proceed to CT for a quick look at the torso. Then go to the most appropriate location to take care of the problem. And if your patient decompensates in CT or angio, immediately proceed to the operating room!
Comparison between laparotomy first versus angiographic embolization first in patients with pelvic fracture and hemoperitoneum: a nationwide observational study from the Japan Trauma Data Bank. Scand J Trauma 21:82, 2013.
Eastern Association for the Surgery of Trauma Practice Management Guidelines for Hemorrhage in Pelvic Fracture-Update and Systematic Review. J Trauma 71:1850-1868, 2011.
Orthopedic surgeons have long found inlet and outlet views (I/O) of the pelvis to be helpful in their management of pelvic fractures. However, for the last decade we’ve seen an inexorable creep in diagnostic imaging from plain xrays to computed techniques. Have the conventional inlet and outlet views lost their luster?
San Francisco General Hospital and UCSF recently published a registry-based study looking at conventional pelvic I/O images and virtual I/O images reconstructed from CT scans. Two years of registry data were reviewed, and included patients had both conventional I/O images and CT imaging. Images were evaluated by two orthopedic traumatologists for their quality.
Sadly, only 20 patients were available for this study, which makes it an interesting pilot at best. The most interesting results were as follows:
Quality of imaging was judged to be equal except when pelvic rotation was present. CT fared better in these cases.
Both inlet and outlet views were judged to be better when reconstructed by CT
Overall, imaging of all portions of the pelvis was about equal in both types of study
The need for repeat studies was identified in nearly half of conventional images, but in only 8% of CT images
Bottom line: CT scanning is slowly becoming the preferred modality for just about any type of trauma imaging. In the 1980’s, head CTs became widespread, followed rapidly by abdominal imaging. Chest CT for definitive diagnosis became commonplace around 2000, and spine imaging by CT has now become the gold standard. Although there are a few throwbacks where conventional imaging has been thought to be better, they are vanishing rapidly. Computing technology can now reconstruct inlet and outlet views of the pelvis, correcting for rotation and angulation in any study of the abdomen/pelvis. And if the reconstructed image is not quite right, the tech can change a few parameters and generate it again and again until the image is perfect.
Orthopedic surgeons should now expect a nicely formatted set of inlet/outlet CT reconstructions in all trauma patients with pelvic fractures.