Kieran Crighton, 14, was left unable to walk, talk, or swallow after being diagnosed with an aggressive form of medulloblastoma in 2017.
One tumour was removed, while the others were blasted with chemo and radiotherapy and an MRI scan showed he is now cancer free.
But the treatment left the youngster with one leg contracted to a 40 degree angle, either due to the amount of time Kieran spent lying down, or because of posterior fossa syndrome, which can occur after surgery for brain tumours.
Medics attempted to stretch Kieran's leg under anaesthetic but it was unsuccessful.
His mum, Senga, 50, is meeting doctors at the Queen Elizabeth University Hospital in Glasgow on Thursday to find out what the prospects are for major surgery to help Kieran walk.
• READ MORE: Scottish schoolboy with five brain tumours makes amazing recoveryHe has re-learnt to speak and to swallow, but Senga is concerned her youngest son, who has Asperger's, has been through enough pain without having another op.
Senga said: "He was in and they tried to stretch it, but they couldn't stretch it fully.
"What they have noticed is that the muscle at the top has wasted away. I think it is going to be a major operation, we are going on Thursday to see the surgeon. His voice has come back, it sounded very robotic at first, it was like Stephen Hawking, but it has got better and better. That was in Easter last year, he still has a weak swallow but he can eat now."
Single mum Senga, who has another son, Darren, 24, put her career on hold for a year to care for her son.
Kieran has now gone back to school for four hours a day.
Senga added: "I think he thought he'd wake up from the anaesthetic and his leg would be flat. I don't want to put him through something that's going to cause him a lot of pain, I think he's been through enough. He's a fighter, he will try and do it."
After the horror diagnosis, Kieran underwent six weeks of radiotherapy and four rounds of chemo but is now back home in Kilwinning, Ayrshire.
His mum added: "It has been a rollercoaster. He is such an inspirational wee boy and he's got a great sense of humour."