Hip replacement surgery may seem fairly standard – but the cost is most certainly not according to a new study, which found that prices quoted for the surgery can vary by more than $100,000 and many hospitals can’t even put a price tag on the procedure at all.

“It was really surprising that only a little over half of hospitals could give us a price – and the range was surprising,” says the study’s lead author Jaime A. Rosenthal, a senior at Washington University in St. Louis who worked on this study with Peter Cram, MD, the director of the division of general internal medicine at the University of Iowa Carver College of Medicine, and Xin Lu, a data analyst at the Iowa City Veterans Administration Medical Center.

Rosenthal made calls between May 2011 and July 2012 to the top 20 orthopaedic hospitals in the U.S. (as ranked by US News & World Report) as well as to two hospitals randomly selected from each state and the District of Columbia. Following the same script each time, she asked for the lowest complete price (including hospital and doctors’ fees) for an elective total hip replacement for her fictitious 62-year-old grandmother who had no insurance but could pay out of pocket.

The study’s findings, published online recently in JAMA Internal Medicine show only nine of the top-20 hospitals and 10 of the 102 unranked hospitals could put a total price tag on the procedure. When Rosenthal made additional calls, she was able to get hospital and doctors’ fees separately from three other top-20 hospitals and 54 unranked ones.

But even though she made as many as five calls to each hospital in search of the data, three top-20 hospitals and 16 unranked ones did not provide any price at all – saying they either had “no way to provide such an estimate,”  didn’t offer those numbers over the phone or required a patient to see a doctor first.

“Some seemed like they were prepared to answer this question and others seemed like they had never received the question before and it took multiple phone calls to get a price,” Rosenthal explains.

Quoted prices ranged from $12,500 to $105,000 at top-20 hospitals that responded and from $11,100 to $125,798 at the unranked hospitals that responded.

Rosenthal says there was no rhyme or reason to the differences. “It wasn’t like the most expensive was the top ranked hospital. It wasn’t that you were paying more to go to the best hospital,” she says. In fact, the average estimate at a top-20 hospital ($53,140) was statistically similar to the average estimate for an unranked hospital ($41,666).

Dr. Cram, a study co-author, says it’s not all bad news. “Sixty percent were able to give us a price estimate. That is really good,” he says. “The other glass-half-full view is, we found some very highly-ranked orthopaedic hospitals – who are national leaders in orthopaedics – that gave us very competitive price estimates.”