How are some people able to continue growing after reaching maturity?

Question

This is technically a cross-post of a question posted last year concerning gigantism and how certain people are able to grow far past expectations after it's assumed they've reached maturity.

How are some people still able to grow after reaching adulthood? Someone gave the answer in the old post that epiphyseal growth plate closure is caused by testosterone and not growth hormones. Is it a lack of testosterone, or an excess of testosterone? If it's a lack, why are women usually shorter than men and stop growing sooner? If it's an excess, does that mean basketball players produce less testosterone than average height people?

There are a number of cases of pituitary gigantism out there, but these are the best examples of what I'm asking:

• Väinö Myllyrinne was 2.22m at the age of 21 but is described as having "experienced a second phase of growth in his late thirties", attaining a height of 2.51m by the time of his death at 54.
• Adam Rainer at the age of 18, he was only 1.22m. However, he had a growth spurt in his 20's, reaching a height of 2.18m at the age of 30 and 2.34m by the time of his death at age 49.

What could have caused these men to grow so much after modern medicine tells us our growth plates have closed? Is there a possibility of replicating their late growth for people who suffer from hereditary short stature or other growth-related problems? And would it be safe?

EDIT: Although my question is different in many ways, here is the original question.

Answer 1

Usually the cause is 'acromegaly' but there are numerous possible causes.

It is impossible to start growing in length after your bones have matured too much. This is because of the 'Epiphyseal plate' this is a anatomical structure in bones that is necessary for length growth in bones and it degenerates at the start of adulthood.

The most common cause, although still not a common disease, for gigantism is acromegalia. It's cause is an abnormally high amount of growth hormone in the body which is most commonly caused by a hormone secreting tumor.

When the onset of this disease happens before the epiphyseal plates have degenerated it can cause them to stay active in which case the patient will continue growing.

Note: When the onset is after the degeneration of the disks it doesn't cause gigantism but it still causes a very recognizable change in appearance and the model for Shrek in the movie suffered from this illness.

Edit: Sorry, I didn't notice your subquestions initially. Yes, another possible cause in men is the lack of testosterone because this hormone is normally responsible for the degeneration of the plates in men.

Edit 2: In women estrogen is the hormone that is responsible for this, which explains why the length of men and women isn't dependent on testosterone in both cases