Tuesday, March 21, 2023

Stemless reverse total shoulder - does this innovation solve a problem?

The forces applied to the humeral component of a reverse total shoulder are greater than those applied to the humeral component of an anatomic total shoulder; thus secure humeral fixation is needed. Impaction grafting of standard length reverse humeral stems provides excellent fixation while preserving humeral bone stock. The standard length stem is applicable to all shoulders, including those with osteopenia. As shown below, humeral bone stock is preserved with impaction grafting of the standard stem.

The authors of Stemless reverse shoulder arthroplasty: Clinical and radiological outcomes with minimum two years follow-up indicate that a stemless reverse shoulder arthroplasty design was developed in order to "preserve bone stock". 

They sought to present the short term (2 year) clinical and radiological results of this implant, but did not test the hypothesis was that this design would provide better clinical and radiological results compared to stemmed implant or that it was a cost-effective alternative to reverse total shoulder with a standard stem.

Scapular notching was observed 26 in 28 patients (24.3%), humeral loosening in 5 patients (4.3%) and glenoid loosening in 4 patients (3.5%). Eight patients underwent an implant revision.

They found complications in 18 patients (15.7%); one patient had two separate proximal humerus fractures after two falls and one patient had a humeral implant displacement and an acromial fracture after one fall. All complications were:
(0.9%) asymmetric polyethylene, 
1 (0.9%)  incorrectly positioned humeral baseplate, 
2 (1.7%) acromial fractures, 
1 (0.9%) case of chronic scapulothoracic conflict, 
3 (2.6%) cases of dislocation, 
1 (0.9%) case of glenoid ossification, 
5 (4.3 %) of humeral implant displacement, 
1 (0.9%) case of glenoid and humeral loosening and
 5(4.3%) cases of postoperative periprosthetic humerus fracture. 

 9 (7.8%) patients underwent a re-operation, in 8 (7.0%) cases the implant was revised.

They concluded that surgeons should proceed with caution when using this implant until longer term follow-up data is available.

Comment: From these results, it does not appear that this stemless reverse total shoulder arthroplasty matches the outcomes and safety of a standard stemmed reverse total shoulder. The high rate of problems related to the implant itself, to instability, to loosening of the humeral implant and to humeral periprosthetic fractures is concerning. Furthermore, evidence is lacking that this implant successfully addresses the problems encountered with a standard implant (see this link).

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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).