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Shrunk not stuck: the naming of frozen shoulder 

Paul Ingraham ARCHIVEDMicroblog posts are archived and rarely updated. In contrast, most long-form articles on PainScience.com are updated regularly over the years (see updates page).

Photo of man grimacing, holding his shoulder.

One of the best things about my job is that musculoskeletal conditions are never as simple as they seem to be. There’s scarcely a single reliable piece of knowledge about any of them. You can always go down a rabbit hole trying to confirm just about anything. Sometimes it gets exasperating: so many rabbit holes that it’s hard to take a step without falling into one! But mostly it’s just the neat part of the job.

This is about one the better examples I’ve ever come across. From an update to my frozen shoulder tutorial

“Adhesive” may be the wrong word: shrunk, not stuck

The formal term for frozen shoulder is “adhesive capsulitis.” And that term assumes the cause of the condition: a sticky joint capsule.

It’s never wise to assume.

Nagy et al (among others) argue that “adhesive” is inaccurate: it’s not an adhered joint capsule, but rather a contractured one. Contracture [Wikipedia] is the shortening or hardening of tissue. In more familiar words, they’re saying the joint has been “shrink wrapped” by a joint capsule that has tightened, rather than being surrounded by loose layers of joint capsule that have gotten stuck together.

What’s in a name? Maybe a lot in this case: this difference could be extremely important to treatment. Sticky layers can be pulled apart; contracture is an issue that’s probably a lot harder to force.

So, what’s really going on? It’s probably impossible to call this one at this time.

We can infer from the partial successes of some surgical procedures that contracture probably isn’t the whole story, so that’s one decent clue. But the main problem with the theory is that just there’s not much information about this adhesion versus contracture business. It seems to have originated with a couple papers way back in 1989 and 1995 (Ozaki et al, Bunker et al) with virtually no confirmation, elaboration, or even contradiction from researchers since then.

I’ll be keeping an eye out. And for now I’ll just point out that there’s a really interesting question mark here.

We know shoulders “freeze,” but we truly do not know how. It’s 2018, and we don’t know that! About frozen shoulder! A condition so common that practically everyone has heard of it, if they haven’t actually had it. Amazing.

 End of post. 
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