Kingston patients who need a hip replacement are subjected to a "postcode lottery" and scored on a points system to decide whether they receive surgery, surgeons have said.
They believe the policy, overseen by GP health commissioners, could affect patients' quality of life and even the outcome of future surgery.
The Royal College of Surgeons of England said in a report: "The use of scoring thresholds may withhold access to surgery for some patients, thereby denying them medical intervention that can improve their quality of life dramatically.
"Delaying access to surgery also adversely affects surgical outcomes, meaning the operation may not be as beneficial as if it had been carried out earlier."
Three-quarters of commissioning groups across the country do not follow government or clinical guidance on referrals for hip replacement, the report found.
A Kingston clinical commissioning group (CCG) spokeswoman said: "While the scores aid the orthopaedic surgeon to come to a decision, it does not block patient referral or procedure for hip replacement surgery.
"Any patient in need of a hip replacement in Kingston will be given one. Since April 2013, there have been 158 hip replacement procedures in Kingston.
"Kingston CCG has a positive track record regarding referrals for hip replacement surgery."