UltraSound as diagnostic

As of right now I do not know of any PTs who use Ultra Sound (US) diagnosticly when looking at a shoulder injury.  The cluster of tests that can be done can narrow down a fairly accurate diagnosis and can certainly determine functional ability and limitations.

That being said, this and this and this say our tests are lousy. Quoting the last one: “At best, suspicion of a rotator cuff tear may be heightened by a positive palpation, combined Hawkins/painful arc/infraspinatus test, Napoleon test, lift-off test, belly-press test, or drop-arm test, and it may be reduced by a negative palpation, empty can test or Hawkins-Kennedy test.”  So do a cluster, is the bottom line.

I reviewed this article:  Prickett WD, Teffey SA, Galatz LM, Calafee RP, Middleton WD, Yamaguchi K. Accuracy of ultrasound imaging of the rotator cuff in the shoulders that are painful postoperatively. J Bone Joint Surg. 2003: 85A(6); 1084-1089 as an appraisal of the subject.

It showed that diagnostic US is .91 in both Sensitivity and Specificity. From my appraisal:

Accuracy:  Correctness of test = 91%

Predictive Validity (+):  91% PPV

Predictive Validity (-):  91% NPV

Pre-test Probability/Prevalence:  50%

Pre-test Odds:   1:1 odds

Likelihood Ratio (+):  10.1

Likelihood Ratio (-):  0.10

Post-test Odds (+):  10.1:1 odds

Post-test Odds (-):  0.10:1 odds

Post-test Probability (+): 91%

Post-test Probability (-): 9%

Pre-test to Post-test Probability(+): 50% to 91%

Pre-test to Post-test Probability(-): 50% to 9%

Those are real nice values no doubt.  The clinical bottom line:

The gold standard of arthroscopic examination should remain the gold standard for research purposes.  Clinically, however, it is invasive and costly.  Diagnostic US is non-invasive, quick and not costly.  Using US along with other special tests would rule out a majority of intact RTC injuries that do not need surgery.  If trained in diagnostic US I believe a PT could use this tool within the scope of practice, no doubt.

Excluding a radiograph to rule-out a fracture, what type of imaging would you want to see for a soft tissue problem?

This tool was tested in the shoulder population and is limited to that body structure in its usefulness and applicability.  There is biologic plausibility to assume it’s usefulness in other superficial body areas as a diagnostic tool.  If my future practice treated a large number of patients in this population, with direct access, I could seek training in this method of diagnosis along with standard examination techniques.

If a patient chart is reviewed and it is shown that they had diagnostic US to the shoulder which was negative for a tear I would be mostly confident (91%) in that result, assuming it lined up with the clinical presentation.  I would not blindly follow the diagnosis, however, knowing that 9% can be missed.

Upon reflection, however, I believe that in a normal OutPt practice setting the use of diagnostic US is not pertinent or needed.  Only if a patient is considering surgery would this non-invasive technique benefit anyone.  PTs work on restoring function.  If that is the goal it is almost pointless to know what the exact damaged structures are past the information we can find out from physical interaction.

If more information changes the treatment approach, then bring it on.  If it just adds to the length of your note then why bother?

What do you think, how much information do you need to treat a patient past a good Subjective and examination? Pathology is important. Find the damaged structure. BUT, functional goals determine how you treat that pathology.

Matt D

 

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2 thoughts on “UltraSound as diagnostic

  1. Pingback: A Year in Review | PTbraintrust

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