Any legs workout (or Gluteus only workout) for bad knees?

[matri.x]

hello,

my wife suffering from arthritis in the knees mainly from pregnancy overweight.

now 8 months after birth she trying to lose weight but cannot perform any HIIT workout because of bad knees.

my questions is:

- Any legs workout with such knees?

- Any gluteus Workout with such knees ?

- Any HIIT workout with such knees?

Thank you