S&N’s New Hinged Knee Builds on Legion™ Total Knee System Heritage

In short

Smith & Nephew has announced the launch of its Legion™ HK Hinge Knee implant to surgeons in the US and Canada. As the first hinged knee to be designed using normal knee kinematics, the implant provides a new option for those patients facing difficult primary or revision knee surgery.


As the moniker suggests, a hinged knee replacement is an implant system in which the three components  of the implant are joined together with a hinged mechanism. Typically, this type of knee replacement is used when a knee is highly unstable and the patient’s ligaments will not provide the support necessary for the more common type of knee implant.

Smith & Nephew’s Legion Total Knee System has quite a pedigree with over 15 years of clinical history and the company is keen to trumpet its continued outstanding clinical results.3 Indeed since its launch, there have been over 1 million primary and revision knees implanted worldwide.

Now the company has taken that design pedigree and turned it into what it is calling next generation rotating knee technology. For patients, the benefit comes from closely matching the knee’s original anatomy while also restoring more normal function. In fact, the design of the implant provides a more natural range of motion1,4 while maintaining an average of 96% condylar loading—a design feature shown to remove the stresses from the hinge link for lower wear on the hinge device.2

For surgeons, Legion HK offers simplicity and familiarity’ picking up cues from the Legion Total Knee System, which allows surgeons to seamlessly transition intraoperatively from a constrained revision implant to a hinged assembly, thus using a minimal number of instruments and the same simple, reproducible surgical technique they already know.

Company comments

“This signals a real change in the hinge knee landscape,” explains Gaurav Agarwal, DSVP and General Manager for Smith & Nephew’s Advanced Surgical Devices division. “With this implant, we are not only simplifying the procedure, we are transforming these complex surgeries from salvage operations to true joint-rescue procedures.”

Clinician comments

“The LEGION HK system is a significant leap forward in treating complex knee revision surgery,” says Dr. Kris Alden, Director of Joint Replacement at West Suburban Hospital in Chicago. “Its kinematic and bone sparing design not only alleviates my patients’ symptoms, but also restores an almost natural knee function. Couple that with its ease of use, and it has greatly aided my practice when treating significant bone and ligamentous deficiencies.”


1Johal P, et al. “Tibio-femoral movement in the living knee”. J Biomech. 38(2): 269-76. 2005.

2Hubbard K,: Condylar Load Measurement of the LEGION◊ Hinge Knee System. Smith & Nephew Inc. Data on file, April 2009.

3Based on GENESIS II clinical data; Knee. 2012 Jan;19(1):8-13. Epub 2011 Apr 14., The Genesis II in primary total knee replacement: a systematic literature review of clinical outcomes., Bhandari M, Pascale W, Sprague S, Pascale V.

4 Dees R, : Design and Optimization of a Guided Motion Hinged Knee System. Smith & Nephew, Inc. Data on file, April, 2012.

Source: Smith & Nephew PLC