Kubica will be out for at least three months and possibly the entire season after suffering serious arm, leg and hand injuries in a rally crash in Italy.
He underwent another eight hours of surgery on Wednesday, his third operation in 11 days, to stabilise and reconstruct his broken right elbow.
The team said doctors were happy with the outcome and Kubica, 26, will remain in intensive care for a few days.
“I would have liked to come back to Formula One in different circumstances, but I’m proud to have been given this chance,” said Heidfeld, who has yet to win a race despite starting 172 grands prix.
The German, who likes the nickname ‘Quick Nick’, drove for Sauber last year after starting the season as the Mercedes test driver and then working with new tyre provider Pirelli.
He was also Kubica’s team mate at Sauber for the best part of four years.
“Everything has happened so quickly, but I’ve been very impressed by what I have seen so far in terms of the facilities and the dedication of the people at Enstone (the Renault factory),” said Heidfeld.
“I really enjoyed the test last week in Jerez and I’ve already settled in well with the guys at the track. I have a good feeling for the car, which is quite innovative. I’m extremely motivated and can’t wait for the season to begin.”
Renault principal Eric Boullier said the team could not afford to waste time on finding a replacement with just two important tests remaining to develop the car before the first of a record 20 races this year.
“We gave Nick a chance in Jerez last week and he really impressed us,” said the Frenchman, who opted not to use any of the team’s five contracted but inexperienced reserve drivers.
“He’s quick, experienced and is very strong technically with his feedback and understanding of the car. We always said the priority was to have an experienced driver in the car and we feel he is the ideal man for the job.”
Kubica’s absence will be keenly felt in Formula One, with the Pole both popular and very fast.
Red Bull boss Christian Horner, whose championship-winning team are also powered by Renault engines, said that Kubica must set realistic targets in planning his recovery and not put pressure on himself.
He added that Formula One’s commercial supremo Bernie Ecclestone was also keeping an attentive eye on one of the sport’s hot properties.
“I’ve spoken to Bernie on a few occasions, who has followed his progress with great interest, and it seems like he (Kubica) has received really good medical attention, the doctors have done a fantastic job for him,” said the Briton.
Source: Bleacher report
In the picture – Nick Heidfeld