Saturday, 15 October 2016

The 4-way range of motion test to exclude elbow fractures; the Sacramento Elbow Rules?

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!


Covering:



No comments:

Post a comment