Many doctors hold to this idea. A recent review of the studies on partial (hemiarthroplasty) versus total shoulder replacements might call that plan into question.
Some studies show that even with a hemiarthroplasty the surface of the shoulder socket continues to wear down and deteriorate. Then when it’s time to convert to a total shoulder, there isn’t enough good, solid bone for the implant.
On the other hand, starting with a total shoulder arthroplasty (TSA) leaves the patient with no place to go if problems occur. There isn’t a good replacement for the replacement.
Overall the studies done comparing hemiarthroplasty to a TSA show the TSA gives patients better function over a longer period of time. More studies are needed to fully compare these two treatment options.