sounds like a tough decision...are the doctors advising one vs the other, or are they completely leaving it up to you?
I had surgery to fuse T8-sacrum about two years ago (ate age 43). It is a very significant loss of mobility, and I personally think it would be extremely hard for an active 13 y/o to cope with. I can't imagine him being able to play high-level soccer after that, but it's hard to say. Lots of people here have posted various opinions about their loss of mobility with fusion. Most are in their 40's at least, and say they find other ways to do almost all of the things they want to do. For me, yes I can still do most of what I want to do, but some things are not easy now (such as picking stuff up off the floor) and I admit I am frustrated by my loss of mobility.
I wonder if you chose the more conservative fusion how many years he would have some added mobility until extending the fusion became necessary. I could really be quite a few, depending on the circumstances. That would be a good question for the surgeon. I really think that to just fuse to sacrum now, to try and save another surgery down the line, might result in a very unhappy boy.
This is all just my opinion, and I hope you don't mind my candor. Best of luck to you and your son in his upcoming surgery. Please let us know how things go.
Gayle, age 48
Boston brace as a teen for AIS
Oct 2010 fusion T8-sacrum w/ pelvic fixation, TLIF at L4/5.
Feb 2012 major A/P revision for broken rods
Aug 2015 rods broken L5
mom of Leah, 13 y/o, diagnosed '08 with 26* T JIS (age 6)
4/08 26 degrees, brace 16 hrs/day
9/08 17 deg. OOB - brace discontinued
9/09 30 deg, resuming brace
5/10 VBS Dr Luhmann Shriners St Louis
4/15 stable 5 yrs post-op, 18* T/ 22* L, Risser 2
also mom of Torrey, 10 y/o son, 16* T, stable