Why We Should Abandon the Diagnosis Term “Impingement”

I think we’d all agree words matter. Especially to patients. So a word like “impingement’ that gives the notion that a tendon is being pinched, compressed, and slowly worn away should be scrutinized for accuracy as it’s like to cause mental stress to a patient. In fact, patients labeled with impingement express feelings of psychological distress, uncertainty, and believe that the condition is serious and has a poor prognosis (Zadro 2021). Is it worth using a word that conjures up scary images? Maybe if it’s the truth, maybe not.  But is “Impingement” the truth?

Where does this term Impingement come from?

 In 1972 a lot was happening. The first commercial home video game console, the Magnavox Odyssey, is released. A famous photo of earth called the “Blue Marble” is taken on Apollo’s final mission. US president Ricard Nixon is implicated in the Watergate scandal. And this was the year a famous orthopedic surgeon named Charles Neer published his paper, “Anterior Acromioplasty for the Chronic Impingement Syndrome in the Shoulder: A Preliminary Report” (Neer 1972). Dr. Neer argued that a wearing down of the supraspinatus tendon and other structures like the subacromial bursa, occur from the overlying acromion, especially when the arm was elevated. His recommendation was surgery to shave away some of the bone to stop the “impinging” of the soft tissues.

It's now 52 years later. Has his theory proved valid and stood the test of time?

Let’s ask a few questions to help form an updated viewpoint on the title of “Impingement:”

1.     Does the known biomechanics support the impingement theory?

2.     Does a subacromial decompression (to increase the subacromial space) work for patients?

3.     How much benefit of an elective surgery is attributable to a placebo effect?

4.     Do other less invasive strategies (like physical or occupational therapy) work for impingement symptoms?

What does the anatomy and biomechanics say?

Neer developed this theory on personal observations. Various studies have questioned the over 90 degrees impingement concept suggesting at lower degrees of elevation the superspinatus already passes under the acromion making it unavailable for impingement (Park 2020; Lawrence, 2019; Giphart 2012)

So if the biomechanical explanation of impingement is correct where soft tissue is impinged under the acromion, then a subacromial decompression should solve the problem, right?

So does subacromial decompression fix impingement?

First, consider that surgeons have given the subacromial decompression a really good try. The surgery increased, from 2000 to 2010, by 746% (Judge 2014). That dramatic increase was not substantiated by strong, objective clinical outcomes.  People did get better, but was it from the required rest from activity that accompanies surgery? From the post-op physical therapy(PT)/occupational therapy(OT)? Or from the placebo effects associated with surgery?

But how could we objectively know if the surgery was helping?

Here’s a few important studies that tested the effects of the subacromial decompression.

One study compared bursectomy (removal of the bursa only) to bursectomy plus subacromial decompression. The addition of the subacromial decompression did not result in a clinically relevant improvement in shoulder function or relief of pain at 12 years’ follow-up compared with bursectomy alone. So, in other words, the decompression was not a variable in the patients’ relief (Kolk 2017).

 Another study compared the subacromial decompression to placebo surgery. For the placebo surgery, an arthroscopy was performed but no subacromial decompression occurred.  The results showed there were no differences in outcomes between decompression surgery and placebo surgery. The authors suggested “The mechanism of the treatment effect in the patients who received surgery might be the result of a placebo, postoperative physiotherapy, or other factors.” (Beard 2018). High quality research from 2019-2021 add more support to there being high certainty evidence of no additional benefit of subacromial decompression surgery over placebo surgery (Paavola 2021; Lähdeoja 2020; Karjalainen 2019).

What about directly comparing subacromial decompression to physical or occupational therapy?

 Again, subacromial decompression fails to provide a benefit in line with it’s risks. It provides no medium term or long-term benefit over exercise/physical therapt (PT) or occupational therapy (OT) (Paavola 2021; Lähdeoja 2020).  

So what do we do with this information?

I treat my patients like I would treat my mom. I want my mom to know the benefit to risk ratio of all medical decisions so, likewise, our patients deserve to know the current research behind proposed interventions.

We must acknowledge the is a “shared decision’ between the patient and the entire healthcare team. And, ultimately, we want patients to not be swayed by us; rather, make informed decisions on their own with the most up-to-date knowledge possible.

So, if a patient is contemplating surgery for impingement, share this information in a professional manner respectful of other professions.

Another power move is to learn how best to conservatively treat impingement. Our shoulder course incorporates all of the latest manual therapy and functional exercise concepts.  Using over 250 peer-reviewed articles, you will not find a more evidence based and clinically effective orthopedic physical therapy(PT)/occupational therapy(OT) shoulder course!

Another great move is to take the advice of several authors and abandon the term “impingement,” even if surgeons around you still use it.  Replace it instead with these two options: “subacromial pain syndrome” or “rotator cuff related pain.” Use the one that feels the most informative and the least scary to you.

Lastly, go on the mountain top and yell “Physical therapy(PT)/Occupational Therapy(OT) works!” Because it does. It works well for impingement, rotator cuff tears, labral tears, bursitis and more. But the public will only know this if we educate them!

 Sources:

1.     Zadro JR, Michaleff ZA, O'Keeffe M, et al. How do people perceive different labels for rotator cuff disease? A content analysis of data collected in a randomised controlled experiment. BMJ Open. 2021;11(12):e052092. Published 2021 Dec 24. doi:10.1136/bmjopen-2021-052092

2.     Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50.

3.     Park SW, Chen YT, Thompson L, et al. No relationship between the acromiohumeral distance and pain in adults with subacromial pain syndrome: a systematic review and meta-analysis. Sci Rep. 2020;10(1):20611. Published 2020 Nov 26. doi:10.1038/s41598-020-76704-z

4.     Lawrence RL, Schlangen DM, Schneider KA, et al. Effect of glenohumeral elevation on subacromial supraspinatus compression risk during simulated reaching. J Orthop Res. 2017;35(10):2329-2337. doi:10.1002/jor.23515

5.     Giphart JE, van der Meijden OA, Millett PJ. The effects of arm elevation on the 3-dimensional acromiohumeral distance: a biplane fluoroscopy study with normative data. J Shoulder Elbow Surg. 2012;21(11):1593-1600. doi:10.1016/j.jse.2011.11.023

6.     Judge A, Murphy RJ, Maxwell R, Arden NK, Carr AJ. Temporal trends and geographical variation in the use of subacromial decompression and rotator cuff repair of the shoulder in England. Bone Joint J. 2014;96-B(1):70-74. doi:10.1302/0301-620X.96B1.32556

7.     Kolk A, Thomassen BJW, Hund H, et al. Does acromioplasty result in favorable clinical and radiologic outcomes in the management of chronic subacromial pain syndrome? A double-blinded randomized clinical trial with 9 to 14 years' follow-up. J Shoulder Elbow Surg. 2017;26(8):1407-1415. doi:10.1016/j.jse.2017.03.021

8.     Beard DJ, Rees JL, Cook JA, et al. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet. 2018;391(10118):329-338. doi:10.1016/S0140-6736(17)32457-1

9.     Paavola M, Kanto K, Ranstam J, et al. Subacromial decompression versus diagnostic arthroscopy for shoulder impingement: a 5-year follow-up of a randomised, placebo surgery controlled clinical trial. Br J Sports Med. 2021;55(2):99-107. doi:10.1136/bjsports-2020-102216.

10. Lähdeoja T, Karjalainen T, Jokihaara J, et al. Subacromial decompression surgery for adults with shoulder pain: a systematic review with meta-analysis. Br J Sports Med. 2020;54(11):665-673. doi:10.1136/bjsports-2018-100486

11. Karjalainen TV, Jain NB, Page CM, et al. Subacromial decompression surgery for rotator cuff disease. Cochrane Database Syst Rev. 2019;1(1):CD005619. Published 2019 Jan 17. doi:10.1002/14651858.CD005619.pub3