How and when do I massage my scars after a breast reduction?

Yes, at 4 weeks if you have no open areas or wounds you can begin to treat your scars.  This can be done in a variety of ways as you suggested.  You can purchase an over the counter topical scar therapy and then apply this along each scar.  You can rub with lotion, a scar therapy or in the shower with a little pressure along the scars as well.  As you mentioned you may feel popping or cracking, this is normal and it is the scar tissue or sutures within it.  You can also purchase the silicone sheets as suggested.  You can buy these on line, just search for silicone sheeting.  They will sell in a variety of shapes and sizes, even sell the pattern to cover a breast reduction exactly.  Wear these as much as possible under your bra, remove for showering, wash them with a little soap and water, let them dry then re-apply the same ones as they should last at least a month.

There is no right or wrong answer concerning tissue massage of scars.  Your massage will soften scar tissue over time.  It may be painful in some areas and those area can be omitted for the time being.  I ask my patients to massage their scars as much as they possibly can.  

It is best to contact your PS to get specific instructions on the massaging that they recommend. Some PS offices do not recommend massaging the scars, that is why it is best to contact the office.