CHARLOTTE, N.C. -- Three-time Sprint Cup champion Tony Stewart underwent successful surgery Thursday in North Carolina to place a rod in his broken right leg.
According to a release from Stewart-Haas Racing, Stewart is out indefinitely.
Max Papis has been named to drive the No. 14 SHR car in Sunday's road course race at Watkins Glen. Officials have not named a driver for the following week at Michigan or any other races.
Stewart broke the tibia and fibula in his right leg during a Monday night sprint car race at Southern Iowa Speedway. He underwent surgery in Iowa after the crash to stabilize and clean the Grade 2 injury.
Thursday's surgery involved placing a rod inside the tibia, pressing it to its anatomic position.
Stewart will remain hospitalized for observation. A discharge date has not been determined.
SHR competition director Greg Zipadelli said Wednesday that Stewart would miss multiple races. He said more would be known after the second surgery.
"Is it six weeks or is it longer?" Zipadelli said. "Honestly, we do not have an answer for that right now.
"As far as next week and on, we have a few candidates. We're talking to a few people. We're not sure if we can put one person in until Tony gets back or we'll use multiple people."
The injury will cost Stewart, who was 11th in the standings and the first wild-card entry, a shot at the Chase. The No. 14 car will remain eligible for the owner's championship.
Dr. Walt Beaver, the co-medical director at OrthoCarolina in Charlotte that heads up the clinic's NASCAR division, could not speak specifically to Stewart's injury, but he told ESPN.com on Tuesday that in general a broken tibia and fibula requires four to eight weeks before the patient can resume somewhat normal activities.
Beaver said everybody heals at different rates from this type of injury. He said a race car driver could come back sooner than an athlete who depends on his legs for running, but there are other inherent risks.
Because a driver sits for a long period of time, Beaver said blood thinners likely would be prescribed to prevent clots. A driver isn't likely to be medically cleared while on blood thinners because that opens the risk of bleeding to death if involved in a wreck.
Once the driver returns, Beaver said the risk of reinjuring the tibia during another wreck isn't great with a rod because the impact would have to be extremely hard to break it.
"Most of them when we put a rod in, then you really can get aggressive with rehab," Beaver said. "You can get back into activities within four, six to eight weeks, but reduced activities of weight bearing."