Doctors have already said he would miss the season while recovering.
On Monday, Johnson was fitted with a Halo brace, which immobilizes the cervical spine and allows for healing. He will wear
the brace for about eight weeks, the Hawks said Tuesday, before beginning four-to-six months of rehab before being allowed to resume his basketball career.
But his prognosis for the long term is good, team physician Dr. Mike Bernot reportedly told the Hawks.
"When we learned how close (the injury) came to being worse, it was very frightening," Hawks president Stan Kasten told the Atlanta Journal-Constitution, setting the measurement at "less than an inch."
The 22-year-old Johnson was injured when his car hit a tree near
his home in south Atlanta early Friday morning.
Meanwhile, the Hawks signed free agent forward Darvin Ham on Tuesday to take Johnson's place on the roster. Ham, 29, played in 70 games with Milwaukee last season, averaging 4.3 points. Ham, who is entering his sixth season, also has played for Indiana, Denver and Washington.
Training camp opens Oct. 1.