Injured Marc Marquez out of Grand Prix of the Americas
"I have just had a CAT scan and it was confirmed that the bone is still in the process of healing," the Spanish rider said on Twitter.
"We have decided not to take any risks and therefore I won't be able to ride in Austin."
Marquez missed the second leg of the season in Argentina with the issue he suffered in the first race of the campaign last month.
Marquez broke his right arm at the start of the 2020 campaign, missed the rest of that season and parts of the next two as he rehabilitated from a series of operations but he did win for the seventh time at the Circuit of the Americas (COTA) in 2021.
"Unfortunately, we won't have the King of COTA with us this weekend!" Honda said on Twitter.
The six-time MotoGP world champion started from pole position in the season-opening Portuguese GP on March 26 but crashed on the second lap and wiped out home favourite Miguel Oliveira.
Marquez apologised but was ordered to ride two "long laps" in his next race.
Honda have appealed the punishment to the international motorcycling federation.
Oliveira, who rides for Aprilia, suffered injuries to his right leg in the crash.
He also missed Argentina but will travel to Austin in the hope of racing. He will undergo a medical checkup on Thursday.
After the first two rounds of the season, Italian Marco Bezzecchi, on a Ducati-VR46, leads the world championship with 50 points, nine ahead of compatriot, and champion, Francesco Bagnaia on a factory Ducati. Frenchman Johann Zarco is third on a Ducati-Pramac.
