Patients are waiting for up to 70 weeks for routine surgery at Londonderry's Altnagelvin Hospital, the Western Trust has admitted.
The shocking delays for orthopaedic operations such as knee and hip replacements has been branded "scandalous".
Sinn Fein MLA Phil Flanagan said it was utterly unacceptable and even obscene that patients were being left in agony because of a lack of available resources.
The Fermanagh/South Tyrone representative said that, in fairness to the Western Trust, it was trying to accommodate people by booking them in to private hospitals. He added, however, that even with this outsourcing to the private sector at massive cost to the taxpayer, the waiting lists were still way off target.
The delays in service have been blamed on an extensive fire at Altnagelvin Hospital at the end of November 2012, coupled with the trust not having the capacity to meet the current demand with orthopaedics.
Health Minister Edwin Poots said recently that the fire and "associated water damage to the wards immediately resulted in several wards being relocated throughout the hospital and to the Waterside Hospital, with some elective surgery in all specialities being cancelled".
Mr Flanagan said that he had been contacted by a number of people who were on the lengthy waiting list in the Western Trust area for orthopaedic surgery.
"Most of these people are in considerable discomfort and urgently need this treatment," he said.
"For anyone to be told that they have to wait 70 weeks for a routine procedure is scandalous."
In response to a query from Mr Flanagan, the chief executive of the Western Health & Social Care Trust, Elaine Way, said: "As a result of a major incident, the trust's capacity to perform elective orthopaedic surgery has been affected and this has resulted in delays in patients receiving their procedures.
"However, the trust is working towards achieving a 30-week maximum wait for patients through use of the independent sector for those patients who are deemed clinically fit to have surgery elsewhere."
Mr Poots, meanwhile, said he had allocated £19m of additional funding to the Health and Social Care Board in 2012-13 to address lengthy waiting times across Northern Ireland.
• Orthopaedic surgery concerns operations to correct problems with bone, joints and connecting tissue.
• Most common among these would be operations like knee and hip replacements.
• It also includes spinal injuries or disorders, dislocations and amputations.