The A605 was closed at Thrapston in both directions between the A45 and B662 because of an accident involving a car and a car transporter.
Northamptonshire Fire Service said they were called to the scene of the accident at about 1.50pm on Tuesday and rescued a woman from their vehicle.
A spokesman added: “Crews from Thrapston, Raunds and a technical rescue vehicle from Mereway in Northampton were called.”
A spokesman for Northamptonshire Police said the woman freed form the vehicle had suffered an arm injury and had been taken to hospital.
He added: “Her injuries are not thought to be life threatening.”