He has a series of range of motion exercises that he has faithfully performed over that time. Then while standing behind raises arm over head x 20. Same with leg raised. Over the last 18 months or so, his joints have started a non-painful clicking that can be felt by the caregiver. We make effort to find a position where this doesn't happen, and are successful only some of the time.
Patient states that the exercise feels good regardless, and wants to continue.
I hate to stop him from doing anything that he can physically participate in. Your question is a good one. Passive range of motion which is the technique you are describing can potentially do harm to patients' joints, particularly in insensate individuals. As you point out, range of motion is important to prevent contractures of joints which is ultimately not only painful, but makes hygiene and positioning difficult. A patient is not likely to move a joint beyond the point of pain if any structural deformity is present.