Researchers at the University of Edinburgh recorded the health states of more than 2,000 people on waiting lists and found 19 per cent were in extreme pain or discomfort.
The level is so poor it is defined by experts as "worse than death" - more painful than chronic health conditions such as diabetes, heart failure or lung diseases.
Chloe Scott, senior clinical lecturer at the university, said: "Patients with the most extreme EQ-5D scores should be a priority for healthcare delivery.
"Indeed, given the overall high levels of pain and disability described by all patients awaiting joint replacement compared with most other illnesses, access to appropriate treatment should be free and available to all at the time of need not limited by cost or bed availability."
The EQ-5D measures a patient's ability to perform routine activities and look after themselves, as well as their levels of mobility, discomfort and anxiety.
Some 12 per cent of a further 2,000-plus patients waiting for knee replacements said they were in a similar condition as those with hip problems.
Scores for both improved dramatically following joint replacement, experts said.
Despite this, patients receiving such procedures are the first to have their treatment limited or cancelled.