Some current thoughts based on recent posts from Physios Dr Peter Malliaras (PhD) and Dr Allison Grimaldi (PhD).
A ‘clinical diagnosis’ is based upon what the client tells us about the onset of symptoms, cause, function and symptoms, combined with what we can test, measure or observe – or something along those lines.
In addition, there’s also the potential input from imaging – ultrasound, MRI etc.
In the absence of symptoms (not reproduced by the test) a ‘sensitive’ test is helpful at ruling conditions ‘out’ (to varying degrees of accuracy but never with ‘certainty’). When symptoms are reproduced by a ‘specific’ test, they would be helpful at ruling a condition ‘in’.
The likelihood of the clinical diagnosis being accurate increases when a highly sensitive test is combined with a highly specific test and clinical history. If the dots align, hopefully we’ve got it right.
Hip pain is common. Hip ‘pathology’ (something identified as having ‘changed’ on imaging) is also common. Most importantly, people can have hip pain with no pathology, and pathology with no pain, so no conclusion can be made between the two without a clear mechanism. It is also possible that an issue elsewhere, such as the low back, could be felt or ‘sensed’ to be in the hip. Finally, and even more importantly, all pain is ‘neurogenic’ in nature, which means that it is an *output* from the nervous system, not an input from the tissues. Pain is can be described as either ‘normal’ and expected (physiological pain resulting from tissue damage, chemical change etc.) or ‘not normal’ (pathological).
Imaging is often considered to be the gold standard if the purpose of the test is to determine the presence of a pathology. The challenge is that the pathology may be unrelated to the symptoms regardless of the test being accurate at confirming the presence of the pathology.
So, that clears up our clinical start point then… [insert sarcasm]
The tests currently used with hip pain are (or at least considered to be the best ones in this article):
1. Hip flexion + adduction + internal rotation + resisted internal rotation
2. Passive hip adduction in side-lying
3. Single leg stance
4. Palpation of the greater trochanter
** An even half (52%) of the people with something (tendinopathy) on MRI felt pain with palpation of the greater trochanter and with at least one other test. That would be sufficient for a ‘clinical diagnosis’ of gluteal tendinopathy.
** Palpation is often painful among people who *do not have* gluteal tendinopathy. In this study, almost half of the group (47%) had pain to touch but no diagnostic reason for it.
** 27% of the people who did not meet the clinical criteria for diagnosis, actually had it on MRI i.e. they were not symptomatic.
** If someone had no pain on palpation, we could say with 80% certainty that is isn’t due to tendinopathy. 20% of the time we would be wrong.
** Everyone who experienced pain while standing on one leg had gluteal tendinopathy on MRI… (100% specificity – hmm), but so did 38% who did not have gluteal tendinopathy.
So there you have it – as clear as mud!
Beware the clinician who talks in absolutes.
What should we do to modify symptoms and (if necessary) improve function?
That’s the art and science of Physiotherapy!!