Sunday, April 2, 2023

Anatomic or reverse total shoulder arthroplasty for B2 and B3 glenoid pathoanatomy?

Severe glenohumeral osteoarthritis (GHOA) with posterior glenoid erosion remains challenging to address for shoulder surgeons, especially for glenoid types B2 and B3.




The authors of Anatomic Total Shoulder Arthroplasty with All-Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies evaluated 66 shoulders with type-B2 glenoids (n = 40) or type-B3 glenoids (n = 26) undergoing total shoulder arthroplasties with a non-augmented glenoid component inserted without attempting to normalize glenoid version. The component was inserted using a standardized technique (see this link) that minimized glenoid bone removal and optimized cementing and seating.



 
The Simple Shoulder Test score improved from
3.2 preoperatively to 9.9 postoperatively at a mean followup of 2.8 years for type-B2 glenoids 
and from 
3.0 preoperatively to 9.4 postoperatively at a mean followup of 2.9 years for type-B3 glenoids.

These results were not inferior to those for shoulders with other glenoid types. 

Postoperative glenoid version was not significantly different (p > 0.05) from preoperative glenoid version. 

The mean humeral-head decentering on the glenoid face was reduced 
for type-B2 glenoids from -14% preoperatively to -1% postoperatively
and for type-B3 glenoids from -4% preoperatively to -1% postoperatively. 

The rates of bone integration into the central peg for type-B2 glenoids (83%) and type-B3 glenoids (81%) were not inferior to those for glenoid types without posterior bone deficiencies. 
None of the total shoulders performed on shoulders with type-B2 glenoids or type-B3 glenoids required revision surgery. 


In spite of this high success rate with this approach to anatomic total shoulder arthroplasty (aTSA), some surgeons prefer reverse total shoulder arthroplasty (RSA) for B2 and B3 glenoids. 

The authors of Anatomic and Reverse Shoulder Arthroplasty for Management of B2 and B3 Glenoids: A Matched Cohort Analysis compared the clinical outcomes of patients with glenohumeral arthritis and Walch B2 and B3 glenoid morphologies treated with aTSA and RSA.

Patients undergoing aTSA were treated with "a standard cemented all-polyethylene glenoid component", however the types of glenoid component and insertion technique were not specified. By contrast, for RSA, all patients had similar implants(AltiVate Reverse). The RSA system includes a glenosphere designed to have a center of rotation lateral to the glenoid (diameter range of 32-40 mm and lateralized center of rotation range of 2-10 mm) and a humeral stem with a 135-degree neck-shaft angle.

Patients were matched 1:1 by sex, Walch classification, and age. However the mean followup for the RSApatients was over a year shorter (mean 47 months for aTSA and 31 months for RSA).

They observed no statistically significant difference between aTSA and RSA for the preoperative change in VAS pain score, SANE score,  ASES score, forward flexion, external rotation or internal rotation.

At a mean of 47 months followup 3 of 101 shoulders with aTSA had gross glenoid loosening.
At a mean of 31 months followup 2 of 101 shoulders with RSA had gross glenoid loosening.

At a mean of 47 months followup complications had occurred in 3 of 101 TSA cases: subscapularis failure, transient postoperative neuropathy, and a revision for infected prosthesis.

At a mean of 31 months followup complications had occurred in 4 of 101 RSA cases : postoperative acromion fracture, transient postoperative neuropathy, transient cubital tunnel syndrome, and revision for glenoid component loosening. 

Comment: While in the report above, primary RSA appeared to yield in largely comparable short-term outcomes compared to TSA in patients with Walch B2 or B3 glenoid morphology, the patients were not matched for length of followup: the aTSA group was followed for over a year longer than the RSA group.

As demonstrated the figure below, complications and revisions continue to increase after shoulder arthroplasty, so in comparing two types of arthroplasty it is important that the periods of followup for the two implants are comparable.

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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 ream and run procedure (see this link).
The total shoulder arthroplasty (see 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).