Hazel Baines, who has dementia, fell on Harrowby Lane, Grantham, at about 17:00 BST on Thursday evening.
Mrs Baines' son, Nigel, said he was "shocked, but not surprised" by what happened to his mother.
East Midlands Ambulance Service (EMAS) apologised, and said it was experiencing "very high demand" at the time of the call.
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Mr Baines, a cartoonist and illustrator, said his mother has dementia and is from the "no fuss" generation, so would not have insisted on an ambulance.
"But, you can tell from the look on her face she was in pain," he said.
He thanked the paramedics and passers-by who helped, but said what happened highlighted the under-resourcing in the system.
"The funds just have to be there to provide the emergency care people need," he added.
His mother was also kept waiting for a further two and half hours at Lincoln County Hospital due to delays in admissions.
In a statement, EMAS said: "In this case, the initial 999 call reported a non-life threatening injury, confirming the patient was alert, sat in a chair and did not want an ambulance sending. The paramedic already en route was therefore stood down and made available for a new 999 call."
Medical director Dr Bob Winter added: "At the time the second call came in we were experiencing very high demand, and so it took us an hour and 52 minutes to get an ambulance to the patient."
"We can only apologise."
Earlier this year, a report found there were "insufficient staff" at the trust to meet the needs of patients in a "timely manner".
Last month, the chief constable of Lincolnshire Police criticised a lack of ambulances in the county.
The service which covers Derbyshire, Leicestershire, Lincolnshire, Northamptonshire, Nottinghamshire and Rutland has about 2,700 members of staff and receives approximately 2,000 calls a day.
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