Department of Orthopaedic Surgery

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Orthopaedic Oncology

Patient Profile

Jennifer Mohring

Custom Knee Replaces Teen’s Cancerous Joint

No one expects knee pain in a 16-year-old varsity water polo player to be cancer. When Jennifer Mohring sought advice about the pain, she was told she suffered from “swimmer’s knee” and advised to do physical therapy.

Following several months of increasing pain, Mohring could barely walk the day after a particularly tough water polo game in early November 2000. This time, a magnetic resonance imaging (MRI) scan indicated a possibility of cancer.

Mohring’s orthopedist contacted the Orthopedic Oncology Service at UCSF Medical Center and Dr. Richard O’Donnell, who performed an urgent biopsy. The bone sample revealed osteosarcoma — bone cancer– in the knee and part of the thighbone called the left distal femur.

“It was so bizarre because a couple of months before I was diagnosed, back when my knee first started hurting, I was telling my best friend that I had a doctor’s appointment the next day, and if I didn’t come back to school, I had knee cancer. I was just kidding around,” Mohring recalls. “My friend said, ‘Wouldn’t it be weird if you had to get a metal knee.'”

What the friends discussed jokingly became reality.

O’Donnell is one of the few orthopedic specialists in the country who does the total knee replacement Mohring needed. But before he could remove her tumor and replace the femur and knee with a custom implant, Mohring went through three grueling months of extensive chemotherapy.

When the time for Mohring’s surgery came, O’Donnell had a special implant ready that replaced the entire knee and about 7 inches of her thighbone. The ComPreS implant device was developed at UCSF to help secure large prosthetic implants to bone without conventional stems and bone cement, which often fail.

“This special implant has been designed specifically for young, active individuals like Jenny, who will place high demands on their legs,” O’Donnell said. “We plan on having her live a long life, and we need prostheses that will stand up to the test of time.” O’Donnell currently is helping to direct a nationwide study of the implant at major cancer centers.

“Dr. O’Donnell is the greatest!” Mohring enthused. “I couldn’t have asked for anyone better to do the surgery than him. I’m so fortunate that he works here in San Francisco, otherwise I would have had to go to Texas or New York or somewhere, to a doctor and a hospital I didn’t know at all.”

Mohring rejoined her high-school water polo team for workouts last season, but wasn’t able to play in games yet. She’s working out with the swim team during the spring and plans to enter a few races. “I’m hoping to be able to play water polo this summer because I really want to be ready to play on the team for my last year of high school,” Mohring explained.

Mohring acknowledged that dealing with cancer isn’t something anyone would choose to do, but the experience has enriched her life in some ways, mostly through the people she has met. Several nurses who helped with her care have become dear friends, including oncology nurse Melissa Strauch. In March 2002, Mohring had the pleasure of walking down the aisle wearing a Cinderella-style dress as a bridesmaid in Strauch’s wedding.