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CADTH » Search All Products » Environmental Scanning » Health Technology Update » Issue 8, January 2008 » Gender Solutions™: Knee Replacement Implants for Women

Gender Solutions™: Knee Replacement Implants for Women

Knee replacement implants designed for women acknowledge anatomical differences and attempt to overcome perceived limitations of existing unisex implants.

hta_update_-8_gender.jpg

Differences between the Gender Solutions™ High-Flex Knee implant and a traditional implant.

Images © Zimmer, Inc. Used by permission only.

Total knee replacement (TKR) is a type of surgery used for patients with advanced arthritis or other conditions who have exhausted all other forms of more conservative care. TKR involves replacing part of the femur (thigh bone) and tibia (shin bone) with two metallic implants that will together function as a new knee. Many implants are currently available for TKR, the majority of which are unisex; smaller sizes are usually used in women.


How It Works

The Gender Solutions™ High-Flex Knee (Zimmer, Inc.) femoral implant was developed following extensive clinical experience with Zimmer’s NexGen™ unisex TKR implant as well as radiographic research comparing the knees of men and women.[1] Differences were noted in the shape, size, and movement of the femur. Based on these anatomic and biomechanical differences, a TKR femoral implant was designed specifically for women by modifying the unisex NexGen TKR implant.

The main differences between the Gender Solutions TKR implant and the unisex NexGen TKR implant are:

  • The Gender Solutions implant is slightly thinner from side to side.
  • The rear portion of the Gender Solutions implant is slightly thinner from front to back.
  • The shape of the Gender Solutions implant is modified slightly to accommodate a woman’s wider pelvis, which affects how the femur moves in relation to the patella (knee cap).

The Gender Solutions implant may improve clinical outcomes following TKR in women and increase patients’ satisfaction with their surgery by providing an implant that feels more natural to them. However, there is no published evidence to confirm such improvements.

Who Might Benefit

There were about 33,600 knee replacement procedures in Canada in 2004-2005; of these, approximately 60% were in women.[2] The Gender Solutions implant is indicated for all female patients requiring TKR, unless they have anatomical deformities in the knee joint. The implant may also be used in some men if warranted by their anatomy.

Regulatory Status

The Gender Solutions implant was licensed by Health Canada in late 2006 under Zimmer’s NexGen licensing. It also received US Food and Drug Administration licensing in 2006. Several other companies have announced plans to market gender-specific TKR implants in the near future.[3]

Evidence

Currently, there are no published trials of the Gender Solutions implant. The evidence to support its claimed superiority over the existing NexGen unisex implant is based on unpublished cadaveric and radiographic studies. Results from recently launched clinical trials of the Gender Solutions knee implant are expected to be available in the next two to five years.

Cost

The Canadian cost for the implant is currently unavailable.

References

[1] The only knee replacement inspired by a woman's shape and size. Warsaw (IN): Zimmer; 2007. Available: http://www.genderknee.com/micro/z/ctl/op/global/action/8
[2] 2006 CJRR report: total hip and total knee replacements in Canada. Ottawa: Canadian Institute for Health Information; 2006. Available: http://secure.cihi.ca/cihiweb/dispPage.jsp?cw_page=PG_387_E&cw_topic=387&cw_rel=AR_30_E
[3] Brooks J. CMAJ 2007;176(3):309. Available: http://www.cmaj.ca/cgi/reprint/176/3/309-a