PPatients waiting for hip arthroplasty suffer from "worse than death" pains, according to a study from the University of Edinburgh.
The research recorded the health status of more than 2,000 people on waiting lists and found that 19% of them experienced extreme pain or discomfort.
The level is so low that experts define it as "worse than death", which is more painful than chronic health problems such as diabetes, heart failure or lung disease.
Scientists who used the internationally-approved EQ-5D measure said that these findings refute the perception that hip and knee arthritis causes only mild discomfort.
Earlier this year, a study found that four of the ten clinical commissioning groups in England rationed their operations at the hip and knee.
In some areas, patients are allowed to participate in NHS operations only if they suffer so much that they can neither sleep nor perform their daily tasks.
The Royal College of Surgeons described the "alarming" and "arbitrary" restrictions.
The EQ-5D measures a patient's ability to perform routine activities and self-care, as well as their degree of mobility, discomfort, and anxiety.
Scores improved dramatically after joint replacement, experts said.
Chloe Scott, clinical lecturer at the University of Edinburgh, said: "Patients with the most extreme EQ-5D scores should be a priority for health care delivery.
"Indeed, given the generally high levels of pain and disability described by all patients waiting for joint replacement compared to most other diseases, access to appropriate treatment should be free and accessible to all at the time of need, without limitation of cost or availability of the bed. "