Fatwa ID: 05431
Answered by: Maulana Yusuf Khan
Assalaamu Alaikum Mufti Sahib. Hope you’re well.
Just a quick question:
An elderly person just had an operation and needs to wear adult nappies because they’re unaware of when they need to go. Currently getting help to go toilet and changing nappy before each salah so they can pray. But doctors advised not to move around or put pressure on the leg (which is the offending limb, that caused the problem in the first place).
So the family is asking; do they carry on changing nappy before each salah and avoid doctors advice or do they leave nappy on and hope for the best and obviously change it as & when needed.
In the name of Allah, the Most Gracious, the Most Merciful
The ruling which applies in this situation is that of an excused person, making new wudhu for each salah and changing the nappy per salah time ensuring the najaasah isn’t there whilst praying. 
However, in this circumstance, one should try their utmost best to change the nappy for each salah time whilst trying to ensure they follow the doctor’s advice in terms of not moving around too much and not putting pressure on the affected leg with the help of someone else.
If this is not possible due to slowing down of healing or lack of help then they should check the nappy before the salah time to see if there is any najaasah (impurity) present then change it if needs be. The amount of leniency depends on the extent to which the problem exists, therefore looking into all of these variables before taking this option. 
Only Allah knows best
Written by Maulana Yusuf Khan
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham