"-on a child, who suffered from the aftermath of an head injury/trauma" this kid that Lis was supposed do a surgery on wouldn't happened to be an albino rabbit, would they?
You are correct, the surgery Dr.Lis Polarny was supposed to approve, was the lobotomy of little Sam Cottontail, who the arctic fox refused.
List would have not been the one to preform the surgery, but rather his colleague, who held the believe that if the lobotomy would be "successful", then he, the colleague would get fame and recognition for their "good work", after all it was the son of an army personnel he would have preformed the surgery on.
Lis did it because he was never fond about the concept of lobotomy, he saw it as butchery and never understood how severing connections of the brain, could do any good in the patients head and mind! There was also the factor that in Lis home country, when it fell into civil war, the government used lobotomy as a justification to silence political opponents and everyone else they saw as "enemy of the state."
The Surgeon, in the present has forgotten who the patient was that was supposed to undergo surgery. However, should one day the Surgeon discover/remember that it was Sam. Let's just say, it won't be as easy for Lis anymore to silence the voices of the other 1999 memories/experiences/knowledge than it was before.