Paul Allen was hit on his left hand side by the right rear wheel of Webber's car, which flew off after it was not attached properly at his first stop.
The Briton was taken to the circuit medical centre after the incident, before being flown to Koblenz Hospital for treatment.
An FIA spokesman has confirmed that Allen suffered two broken ribs, a broken collarbone, concussion and bruises.
It is likely that he will remain in hospital under observation until early this week.
Red Bull was fined €30,000 for letting Webber's car leave the pits without the wheel attached.
- Disease & Medical Conditions