Exercises for Osteoporosis
With cases such as this, it’s always imperative to contact a professional in the field regarding the predisposition/ailment. Personal Trainers aren’t medical professionals despite their knowledge.
Just from the outside looking in, and making some assumptions, I would recommend low-impact resistance training to increase joint health and muscle strength/retention.
Depending on this individual’s current fitness level, age, or doctor’s recommendation, you can then assess which more impacting exercises to implore.