All kinds of clinical decision instruments have been sprouting up over the past few decades. Perhaps the most
famous are the “Ottawa Ankle Rules” dating back to 1992.
There have been several
attempts at a decision instrument for the elbow and this is probably why
this latest offering was published in a lesser impact journal. Nevertheless, this
version is quite promising.
The authors sought to prospectively validate their “4-way range of motion test" for the elbow.
(As an aside... there
is no doubt that the lead author Dr David Vinson is a clever dude, but I think
he may have failed in the marketing department. Nobody is ever going to
remember the “4-way range of motion test,” nor is it very catchy. So I’m going to call it the Sacramento Elbow
Rules until he can think of something better.)
They enrolled a convenience sample of patients 5 years and
older with an acute blunt elbow injury if the clinician felt that x-rays of the
elbow were indicated. They assessed the performance of the rules compared to
the gold standard diagnosis of a fracture or effusion seen on plain
radiography.
The 4-way range of motion test... woops, Sacramento Elbow Rules are:
- Full extension to 0°
- Flexion to 90°
- Full supination (with arm flexed at 90°)
- Full pronation (with arm flexed at 90°)
If the patient could not perform any one of the manoeuvres,
they were considered to have failed the rules, thus requiring an x-ray. (To be clear, all patients got x-rays for
the purpose of this study.)
Results?
They included 251 patients in their analysis. There were 99
positive x-rays. The test had a sensitivity
of 99% (95% CI, 94-100%) and a specificity of 60% (95% CI, 54-69%). This is
pretty darn good.
There was one false
negative in a 7 year old boy with an undisplaced supracondylar fracture.
It is refreshing to see a paper with such an excellent discussion section. The
authors suggest their rules may not be perfect as the lower level of confidence
interval (CI) for sensitivity is not as high as 97%. But they wisely mention
that a much larger study to narrow down the CI would be challenging and fail on
feasibility. What we have is probably
good enough especially since a missed subtle fracture is probably of lesser
consequence than other high risk clinical scenarios.
I agree. This is probably a decent piece of information that
should aid the clinician. It also passes
the sniff test (face validity). If a patient can fully extend, flex and
supinate & pronate then they probably don’t have a fracture. I’m willing to
believe this. No rule is perfect but I think this is ready for prime time.
Bring on the Sacramento Elbow Rules!
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