Jason McCash was also given an extended licence period of three years after Judge Beverley Lunt, sitting at Preston Crown Court, deemed him to be a dangerous offender.
Officers were called to Marlborough Road at 11pm on January 27 following the break-in.
The victims, a woman in her 60s and a man in his 70s, answered a knock at their door, believing it to be their son. It transpired to be two masked intruders – one later identified as McCash – who demanded money.
McCash hit the male victim over the head and pushed him to the floor. McCash then threatened the female with a knife and pulled her to the floor. She managed to drag herself along the floor and call the police.
A handbag and the couple’s Vauxhall car were stolen, although the vehicle was found abandoned a short time later on Lee Street.
The couple were taken to hospital but their injuries were not life-threatening and they have since been discharged.
Later that evening, McCash was taken to Royal Preston Hospital with a significant stab wound to the stomach – an injury sustained during the melee of the robbery.
McCash, 36, of no fixed address, and a female associate, claimed his injuries were as a result of an altercation with a woman they both knew.
This led to the arrest of a woman in her 30s, who spent several hours in custody before it was established she had nothing to do with McCash’s injury. She was released no further action.
McCash was interviewed and charged with two counts of robbery, the unauthorised taking of a motor vehicle and conspiracy to pervert the course of justice. He was also charged with a burglary at a residential property which he had committed on the night of January 26.
DC Rubina Akoo, of East CID, said: “This was a despicable crime committed against two vulnerable victims in their own home. Not only did McCash act with callous disregard to his victims’ welfare, he also concocted a lie about how he received the stomach injuries. That led to the arrest of a woman he knew was completely innocent of any wrongdoing in this case.
“I welcome the sentence handed down by the Judge and I am also pleased that she rightly deemed McCash to be an individual who poses a danger to the public. He will now be off our streets for a considerable period of time and I hope the public feel reassured and are able to sleep that bit easier at night.
“I would also like to praise the bravery of the victims, who not only showed considerable courage on the night of the robbery but have continued to do so throughout the weeks and months leading up to sentencing.
“Finally, I hope this sentencing outcome will encourage other victims of crime to come forward, knowing that Lancashire Constabulary will always act with professionalism, compassion and will a strive to bring offenders to justice.”