Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
These issues usually require timely clinical advice but are not automatically emergencies.
These symptoms require emergency care.
Contact the treating team promptly for worsening bowing, a new limp, increasing knee pain, brace-related skin sores, or concerns about a cast or surgical wound.
After surgery or while wearing a cast, seek urgent medical assessment for increasing pain that is not controlled as expected, marked swelling, spreading redness, fever with wound drainage, new numbness, or difficulty moving the toes.
Routine follow-up usually includes examination of leg alignment, walking, knee movement, and leg length.
Standing X-rays may be repeated at intervals chosen by the orthopedic specialist.
Children using a brace need appointments to assess fit, skin health, and response to treatment.
The article also says
After guided-growth surgery, regular imaging is especially important.
Continued correction can eventually move the leg past the desired alignment if the hardware is not removed or adjusted at the appropriate time.
Children who have an osteotomy need monitoring of bone healing and alignment.
A cold, pale, or blue foot, sudden loss of feeling or movement, severe rapidly increasing pain, or a very tight and swollen limb may signal a problem with circulation or pressure in the leg.
Every sign above is quoted from the sofidex article on Blount disease. If you are not sure, err upward — it is always reasonable to be checked.