There are some communities out there who do not wish to accept women who have chronic issues, simply because of the possible medical bills attached to them. . .ie: a diabetic who has to pay for insulin and blood sugar supplies. I know of several sisters who have had various issues and were not accepted in the first community they inquired after, or were sent away after entrance, when health issues popped up.
Some, to be honest, might say, they do a lot of kneeling (especially cloistered monasteries) and so, you need to be able to do so to be accepted. And they may not make concessions for you. I know of a sister whose knees used to bleed, she was on her knees so much. . .but her superior would only say 'well don't kneel during this but still kneel during that' and silently crying, that sister still knelt, in penance. Some monasteries may have their cells(bedrooms) on an upper floor, so you need to be able to climb stairs to get to it. Some communities want you to be able to 'do your fair share' and may feel, in their minds, that this is an impediment to your doing so. Each community SOO varies!
If you contact and/or visit a community and they tell you that they cannot accept you for this reason, do NOT be discouraged!

It just means this isn't where our Lord wants you. While it may seem ideal to you, and you cannot imagine why you aren't accepted in whatever community you're considering, (and you are tempted to stop discerning religious life altogether) know this:our Lord sees behind the scenes and knows that which you know not. If you are called to the reliigious life, this is one of the ways He guides you to the place He's chosen for you from all eternity.. . by closing some doors, so that you go through another. I hope that doesn't sound too much like a downer. I just know that each community is different than the next. One might say 'no, we can't accept you' and allthewhile, the next one is saying 'so what if you have_______ ?' He will show you where you are to go!
By the way, yes, Mother Angelica had knee issues early in her formation, and in fact has had health issues all her life, off and on, but each person is an individual when it comes to vocations, you know? Like I said, I've known sisters who were prevented from entering or were sent away, due to health issues, that seem to make no sense, as they had others in their communities who had health issues as well. . . but each of the 3 sisters I am considering specifically, went to other communities, were accepted and are now incredibly happy. . .something they may not have been, had they stayed in the situation they were in previously.
Funny how God works, eh? Don't worry. . .just be open with the community, and God will do the rest

God bless you. I will keep you in prayer.