Does Preservation of Coracoacromial Ligament Reduce the Acromial Stress Pathology Following Reverse Total Shoulder Arthroplasty?
These authors point out that acromial pathologies (AP), such as acromial stress reaction (ASR), acromial stress occult fracture (ASOF), and acromial stress fracture (ASF), are known as complications that compromise the outcome for patients having reverse total shoulder arthroplasty (RSA).
They point out that the coracoacromial ligament (CAL) distributes the stress on the acromion.
In 265 patients, they investigated the incidence of AP according to the preservation (68) or sectioning (197) of the CAL.
ASR and ASOF were identified through symptoms and ultrasound, and ASF identified through simple radiograph or computed tomography.
In the 197 patients with CAL sectioning
there were 21 cases of ASR(10.7%), 28 cases of ASOF (14.2%),10 cases of ASF (5.1%), and 59 cases of total AP (29.4%).
In the 68 cases with preservation of the CAL
there were 2 cases of ASR (2.9%) , 6 cases of ASOF (8.8%), 1 case of ASF (1.5%), and 9 cases of total AP (13.2%).
Comment: These clinical results are consistent with the results of a recent cadaver study:
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."
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link). How to x-ray the shoulder (see this link). The total shoulder arthroplasty (see this link). The ream and run technique is shown in this link. The cuff tear arthropathy arthroplasty (see this link). The reverse total shoulder arthroplasty (see this link). The smooth and move procedure for irreparable rotator cuff tears (see this link). Shoulder rehabilitation exercises (see this link).
