English to French Medical Medical: Instruments shoulder surgery (rotator

Technical medical document dealing with Reversed total shoulder arthroscopy

Context:
With the inverted bearing and the hard humeral inlay, it was possible to reduce the wall thickness at the humeral components significantly, and therefore, the humeral bone loss could be reduced.
The bearing diameter 36 and 42 mm was proven as minimum and maximum sizes, but often the step between 36 and 42 mm was too big.
Hence, a third size in between (39) was introduced to get more options for an improved soft tissue balancing.

I cannot understand want this sentence means.the bearing diameter was proven?? tested as minimum and maximum sizes?
I have already accessed quite a few French texts on this topic, but if anyone can suggest a French document where these particular terms come up, I would be very grateful (it would save me having to continually ask questions)