A sterilization problem at the Royal Alexandra Hospital in Edmonton postponed dozens of orthopedic surgeries last week.

Hospital staff noticed an unidentified substance on some linens wrapped around surgical equipment last Friday, said Dr. Eric Estey, chief of surgery. 

'These are uncharted waters for us unfortunately' - Dr. Eric Estey

The problem re-occurred intermittently over the last week, but staff do not know why.

Fearing for the safety of patients, the hospital postponed 51 operations, primarily joint replacements . 

"We don't take the decision lightly to postpone anyone's operation," Estey said. "I recognize as a surgeon the impact that this has on a patient, their family.

"Until we actually define and identify this staining substance, then we're erring on the side of caution for our patients."

Tests showed the sterilizers were working properly and there did not appear to be a problem with the way the linens are cleaned.

The residue is being analyzed with the results expected next week.

The hospital does not believe the substance is a biological or an infectious contaminant, Estey said.

In the meantime, the hospital is sending the surgical equipment to other hospitals for sterilization so surgeries can go ahead on Monday. 

AHS said the hospital will add operating-room time next week so some of the delayed surgeries can be completed.

Estey said he has not seen this problem before. 

"These are uncharted waters for us unfortunately," he said. "Incidents like this do occur in medical device reprocessing units across the country as we've heard, but often they don't find out why it comes and goes."