Dallas July 18, 2006 Orthopaedic surgeons at UT Southwestern Medial Center are the first in North Texas to use knee implants specifically designed to fit a woman's anatomy.

The implant addresses three distinct and scientifically documented shape differences in women's and men's knees. Designed using three-dimensional computed tomography imaging, the Gender Solutions High-Flex Knee more closely mimics the joints and inner workings of women's knees.

"We'll be the first in Dallas to use the new design," said Dr. Robert Bucholz, chairman of orthopaedic surgery at UT Southwestern. "This is one in a series of technical improvements in the design of knee implants that is long overdue."

During total knee replacement surgery, or arthroplasty, surfaces of the thighbone (femur), the shinbone (tibia) and the kneecap (patella) are replaced with a metal-and-plastic implant.

Traditionally, the implants have been designed based on men's knees. For women, smaller implants were used, but size did not resolve the anatomical differences, which sometimes accounted for pain and discomfort and an "awkward" feeling.

Researchers have found numerous shape differences between the average male and female knee. The new replacement, created by Zimmer, Inc., of Warsaw, Ind., and approved in May by the Food and Drug Administration, addresses three gender-specific issues:

• Narrower shape: Knee implants are typically sized by measuring the end of the femur from front to back and from side to side. Most women's knees are shaped like a trapezoid and narrower from side to side; men's knees are more rectangular. Implant size is typically based on the front-to-back measurement to allow the knee to move and flex properly. In women, however, an implant that fits from front to back can be too wide from side to side, sometimes causing it to overhang the bone.

• Thinner density: Typically, the bone in the front of
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