Why Shape Matters

Replacing a worn out joint isn’t just about relieving pain as it was some years ago. Nowadays patients expect a more functional joint which enables them to continue with their increasingly active lifestyles. In the UK, more than 30,000 people undergo knee replacements each year, and nearly two thirds are women. Historically, knee joints were made the same shape but in different sizes. Now it is recognised that people’s joints are a different shape as well as a different size.

This is particularly evident between men and women. Research shows getting a good fit is not just about size, it’s about shape. Everybody knows that women are different from men and research shows that we differ all the way down to our knees. Yet, up to this point, the design of all knee replacement implants have been based on an average size of both women’s and men’s knees combined. Women suffer from more knee pain than men. Yet, traditional knee replacements were not designed with a fit and function specifically to accommodate the different shape and size of a woman’s knee. As the number of women requiring knee replacements grew, leading orthopaedic surgeons began reporting the need for more frequent adjustments during surgery in order to make the traditional implants fit.

It became clear that it was time for a knee implant specifically designed to fit the shape and size of women’s anatomy. The orthopeadic specialist company, Zimmer, analyzed computer tomography scans on more than 800 female and male knees. This research led to the design of the gender knee, which incorporated the distinctive features that address the anatomical characteristics of the female knee. Implant designs that distinguish between female and male anatomical differences allow for improved fit and fewer intra-operative adjustments. As a result, the Zimmer Gender Solutions Knee was born and we could look at knee replacements in a new way. It is the first and only knee replacement shaped to fit a woman’s anatomy. The design is based on research that confirmed the differences between women’s and men’s knees that surgeons were seeing in the operating theatre.

For patients with less severe disease we can replace just the part affected by wear changes. This allows a smaller procedure, more rapid recovery, plus the ability to return to more active sports. Using the Zimmer Unicondylar High Flex Knee either on its own, or with the Gender Solutions Patello-Femoral Joint, one or two compartments of the knee can be replaced to provide a clinical solution for presentations of disease in the patellofemoral area and one of the distal condyles. These smaller procedures are compatible with minimally invasive surgery (MIS) techniques, which facilitate smaller incisions, less tissue trauma, quicker recovery and shorter hospital stays. Michael Moss performed the first Gender Solutions Knee replacement in the UK in March 2007, and has done many more since with excellent results.

Shape does make a difference!

Mr Michael C Moss MB FRCS is a consultant orthopaedic surgeon practising at the Nuffield Health Chichester Hospital.