Hi there and welcome.
I've been in your shoes more than once. I won't get in to too many details about my surgical history, but my first surgery started with Brostrom repair, peroneal tendon repair and we found at the time of surgery, microfracture for 2 OCD lesions.
Now, to answer your questions. Is it common to have it redone and does it last? For most people, once is enough of the Brostrom and it does last. I say most because people like me, who have multi joint hypermobility syndrome the answer is, it doesn't last as much. So ask yourself, it it only your ankle, or are all your joints hypermobile? You probably know and have been told all ready if you are. Now, my first OS didn't look in to this and I didn't tell him. So he did a modified Brostrom repair, fixed my peroneal tendons, and their subluxation as well and did the microfractures.
A year and a half later I was back in surgery for everything to be redone again (except for the subluxation of the peroneals) PLUS an OATS (don't worry about this yet) on one of my OCD's. My surgeon this time knew about my hypermobility and so he first was going to use a cadavaar tendon but used something else instead. This time the Brostrom lasted. It was all about not just sewing my ligaments together again. It was too late for my OCD's though.
The Brostrom will be so worth it. The recovery isn't bad at all except for the pain in the behind of being on crutches. The microfracture is what is going to be the key, for the OCD. Do you know how big it is? That is why 6 weeks of NWB is important for the microfracture. Rehab is slow for both, but you need months for the scar tissue from the Brostrom to get nice and strong. You don't want to run on your ankle too early for the OCD to heal.
Let me know if you have any more questions. I've had 2 Brostroms, multiple tendon repairs, microfracture in 4 different surgeries, OATS on one of the OCD's, distraction arthroplasty, and I'm still not done. So related to unstable ankles or OCD's, I've probably had it done and will be happy to answer questions about it.
BTW, my body is weird with my ligaments/tendons tearing all the time and most time microfracture works great on OCD's and if not then the OATS does. So I'm just not the norm when it comes to my results, so don't let that scare you.