Claire Busby, from Maidenhead, Berkshire, took legal action against Berkshire Bed Company, also known as Beds Are Uzzz, who she claimed sold her a faulty product.
Ms Busby, 46, suffered the injury when she fell from the super-king-size double divan as she was changing sex position.
She claimed the bed was in a “defective state” at the time of the accident but Judge Barry Cotter ruled on Friday her fall was a “tragic accident”.
Judge Cotter said: “As a result of the matters set out above, the claim in relation to this tragic accident, which is what I find it was – a simple accident – fails.”
Ms Busby told the court she was injured a week after the bed’s delivery while having sex with her then-partner, John Marshall.
She said she was kneeling in the middle of the bed and decided to move position and “swung her legs” from underneath her, before lying back on the bed with her head towards the bottom end.
She claimed the bed then gave way and she fell off the end, landing on her head.
Ms Busby said: “I spun around, I put my hand down and then I felt like I was catapulted off the back of the bed.”
Two gliders, or feet, were found to be missing from the bottom end of the bed, but this was not believed to be the cause of the accident.
Judge Cotter concluded a “much more likely cause” was the “unusual position” Ms Busby was in, kneeling back on her feet towards the foot of the bed.
He added: “Having carefully considered the totality of the evidence I am not satisfied that the difference in level between the two divans played any part in Ms Busby’s loss of balance backwards.
“Rather, I am satisfied that this was a simple but tragic fall; she simply overbalanced probably in part because she was sitting on a mattress as opposed to a firm surface and underestimated the amount of give underneath her body.”
Richard Manders, director of Berkshire Bed Company, welcomed the ruling.
“We are delighted the court has ruled in our favour,” he said. “We are sorry that Ms Busby was injured and we wish her and her family well for the future.”
Agencies contributed to this report