By CBS 2 Chicago Staff

BROOKFIELD, Ill. (CBS) — A tiger that underwent groundbreaking hip replacement surgery at Brookfield Zoo will now be needing a new surgery after the implant was dislodged.

When the 10-year-old Amur tiger, Malena, arrived at Brookfield Zoo last summer, she already had degenerative arthritis. It’s a common disorder in older animals.

READ MORE: Chicago Weather: Warming Trend Continues, Rain Chances Persist

On Wednesday, doctors there performed a total hip replacement with a custom-designed implant.

The surgery took longer than expected at six-and-a-half hours. But the doctors initially said it was a complete success.

But it turned out there was a problem. Overnight as Malena started moving around, she exerted force on her leg and the part of the implant that was attached to her femur was dislodged, the zoo said Thursday.

READ MORE: 3 Men Injured In River North Parking Garage Shooting, One Identified In Video As Rapper Lil Reese; Officer's Gun Also Accidentally Discharged

Thus, Malena will now need a new surgery. The implant will be taken out, and another surgery called a femoral head and neck excision will be performed on Saturday.

“We knew going into this groundbreaking surgery, there was a risk of complications given the incredible forces generated from a tiger’s leg muscles. However, with the severity of Malena’s arthritis, we also knew surgical intervention was the best option to keep her comfortable,” Dr. Mike Adkesson, vice president of clinical medicine for the Chicago Zoological Society, sad in the news release. “Going into surgery, we knew if it was not successful, we still had a secondary option to relieve her discomfort. While she won’t have the high level of function we were hoping to restore with the innovative total hip replacement, Malena will be able to move around comfortably without pain in her hip.”

The “head and neck” referenced in the surgery does not refer to Malena’s head and neck, but the portions of her femur – or thighbone – that are called the head and neck. Those portions of the bone are arthritic and will be removed, allowing a fibrous joint to form and for the leg muscles to stabilize the joint, the zoo said.

The initial surgery was performed by Dr. James Cook, the Allen Distinguished Chair in Orthopaedic Surgery and director of the Mizzou BioJoint Center at the University of Missouri. He will assist the veterinary team for the new surgery as well.

MORE NEWS: At Least 31 People Wounded In Weekend Gun Violence In Chicago, 5 Killed

Also From CBS Chicago:

CBS 2 Chicago Staff