Tuesday, April 28, 2020

Don't cut the coracoacromial ligament! (Codman)

Scapular Ring Preservation: Coracoacromial Ligament Transection Increases Scapular Spine Strains Following Reverse Total Shoulder Arthroplasty

Stating that the coracoacromial ligament (CAL) is often transacted during surgical exposure for reverse total shoulder arthroplasty (RSA), these authors hypothesized that the CAL contributes to the structural integrity of the “scapular ring” and that the transection of this ligament during RSA alters the scapular strain patterns in a way that may contribute to scapular fractures following this procedure.

They performed RSA on 8 cadaveric specimens and measured strains at the acromion and scapular spine before and after CAL section while a shoulder simulator positioned the joint in 0, 30, and 60 of glenohumeral abduction.

With the CAL intact, there was no significant difference between strain experienced by the acromion and scapular spine at 0, 30, and 60 of glenohumeral abduction. 

CAL transection generated significantly increased strain in the scapular spine at all abduction angles compared with an intact CAL. 

They concluded that the  CAL is an important structure that completes the “scapular ring” and therefore serves to help distribute strain in a more normalized fashion. 

Comment: In his 1934 book, E. A. Codman wrote prophetically, "The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation."

We have not found it necessary to divide the CAL "at any operation." Not only is it a halyard stabilizing the scapular spine and acromion to the robust coracoid process, as suggest by this study, but it is also an essential element of the stabilizing coracoacromial arch.

which, when sacrificed, risks anterosuperior escape

which, in turn, is one of the reasons for performing a reverse total shoulder. 

So, we agree with Codman, "The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation."

To see a YouTube of our technique for a reverse total shoulder arthroplasty, click on this link.
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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

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