Is Impingement Dx Specific Enough?

Numerous doctors in the area have stopped using the term impingement due to lack of specificity of structures involved and combination of intrinsic and extrinsic factors. I do like a good debate, especially when it comes to specificity of our examinations. Two articles discussed today compiled tests to assess their clinical utility – they utilized surgery as a gold standard. Let it be noted that if you are a surgeon – I agree to be more specific in terminology as you have a clear picture of intra-articular structures involved.  Although, from a clinic standpoint – testing we rely on gives us part of a full picture. MRI is the next in line for clinically useful tool but can be debated its use as health care costs are rising – and we know many  asymptomatic patients have rotator cuff tears. Thus it begs the question – does it tell us the whole story? Especially as a 1999 study showed 23% of asymptomatic patients have RC tears and this number rises with age where half of patients older than 80 years old have asymptomatic RC tears.⁴ If this is the case, and patients with rotator cuff tears do not have pain or limitation – why do patients with rotator cuff pathology end up in our office? This first question is up for debate, and will be discussed at a later date. Two questions I will touch on- what tests are practically useful in clinic – and what do they tell us?

I utilize Park et. al recommendations for clinic. They found clustering tests gives us higher diagnostic utility in ruling in impingement.³ What this article did, which I found interesting, is break down testing into involved tissue. Here comes back the debate – can we tell what tissue is involved? In this study, they broke down groups into three areas – group 1 with bursitis – group 2 with partial thickness tears – group 3 with full thickness tears. The best specificity found with group 1 was cross body adduction test, but only lent us a sp =. 79.³ Better test for bursal involvement is a negative Neer test, as this was found to be quite sensitive at sn = .81-.89. This may be a better way for us to rule out bursal involvement but no test to date has been shown to isolate and rule in bursal pathology.^2,3,7 Much better utility was demonstrated with impingement and full thickness tear testing – especially when clustered as seen in Table 1.

Table 1:³

Another article to review for diagnostic testing is Michener et. al. who reviewed clinical exam items as well – they found lesser utility of clustering tests. Although I would debate this is a worse study to hang our hats on as the sample size was about 17 times less than the Park et. al study. They did confirm that we have fair to substantial inter-rater reliability with all impingement testing.² They also confirmed the sensitivity of Neer to use as a screening tool for SIS. Neer test may be more useful as we clear out RC pathology as we screen shoulder’s involvement if we are evaluating another joint as our primary concern (i.e. cervical spine).

Overall, clinical testing does an excellent job when clustered to tell us that the patient is experiencing some “impingement” of the rotator cuff and/or biceps tendon or bursae. Unfortunately, we have no clinical testing to differentiate between these structures yet. Thus, even though, yes, this diagnosis has numerous factors that play into its presentation from a clinical diagnosing standpoint; I only feel confident from a clinical examination to call it impingement then speculate at involved structures.

Original post: September 16, 2013

References:

1) Neer, C. S. (2010). Anterior Acromioplasty for the Chronic Impingement Syndrome in the Shoulder : A PRELIMINARY REPORT Anterior Impingement Syndrome for the Chronic in the Shoulder.

2) Michener, L. a, Walsworth, M. K., Doukas, W. C., & Murphy, K. P. (2009). Reliability and diagnostic accuracy of 5 physical examination tests and combination of tests for subacromial impingement. Archives of physical medicine and rehabilitation, 90(11), 1898–903. doi:10.1016/j.apmr.2009.05.015

3) Park, H. Bin, Yokota, A., Gill, H. S., El Rassi, G., & McFarland, E. G. (2005). Diagnostic accuracy of clinical tests for the different degrees of subacromial impingement syndrome. The Journal of bone and joint surgery. American volume, 87(7), 1446–55. doi:10.2106/JBJS.D.02335

4) Tempelhof S, Rupp S, Seil R. Age-Related Prevalence of Rotator Cuff Tears in Asymptomatic Shoulders. Journal of shoulder and elbow surgery.1999; 8: 296-299.

5) Hegedus EJ, Goode A,  Campbell S et al.  Physical examination tests of the shoulder: a systematic review with meta-analysis of individual tests. Br J Sports Med 2008;42:80-92

6) Eric Robertson. (2013 September) Current Best Evidence For The Diagnosis And Treatment of Subacromial Impingement Syndrome.  Lecture conducted through EIM.