What makes a knee joint a good joint ?


According to their experiences, amputees often have unique, very individual needs. So typically, the problem for an artificial knee designer is to capture as many of the essential features in a design that will produce an artificial leg with the ‘best’ technology available, that is, either created (like the patented VGK microkinetic processor technology) or that is traditionally ‘proven’ by known technologies.

There are significant qualitative differences, in the feel of different kind of knee joints, since knee joints in an artificial limb for trans-femoral amputees can give very different experiences. In an ideal world, the best way an amputee could find out what works for them, is to try out a variety of alternative based technologies.  The feel of the knee may range from a crude hinge to something that many amputees, who have tried out the VGK, have spontaneously called: “A Very Good Knee joint, one that feels very close to one’s own leg”

When looking for a better knee joint, better questions need to be asked:

1) Is the current knee joint stable in most conditions?

(In other words, do you fear that the knee will collapse if you are not careful?)

Ask yourself:

Do I need to make a special effort to keep it from collapsing?

Do I struggle to walk-and-talk?

Does my knee joint give way when it is not fully straight if I walk downslope? 

IF YOU ANSWER ‘YES’ TO ANY OF THESE QUESTIONS, read on, the VGK may offer you something useful.


Ask yourself:

Can I keep up with other people walking?

Does my leg feel nice in swinging through?

Can I push my leg forward through grass? 

IF YOU ANSWER ‘NO’ TO ANY OF THESE QUESTIONS, read on, there could be something better.

3) Can I walk leg over leg downstairs?

Ask yourself:

Do I kind of jump over my false leg to make it look like as if I do?

Does the knee kind of lock up or collapse if I try?

Does my knee make me scared to try in the first place? 

IF YOU ANSWER ‘YES’ TO ANY OF THESE QUESTIONS, then you may not have tasted the pleasure of controlled stairs descent.

4) Can I walk leg over leg down slope?

Ask yourself:

Does my knee sometimes shoot if I try?

Does my knee get stuck solid if I attempt?

Does the knee fail me when it gets hot? 

IF YOU ANSWER ‘YES’ TO ANY OF THESE QUESTIONS, then you may not yet have a knee that ‘does the job’. Since the VGK-Go! is designed to do this very well. The VGK-Go! could have some answers for you. We believe the Very Good Knee offers solutions. It’s a knee joint with that naturally adaptive response, created by the patented use of fluid-flow reactive to the needs of the immediate movement


If you think so, measure, whilst sitting, from the end of stump to end of knee cap of the other leg, and if you measure more than 20 cm (8″) then you may have a short stump.

Ask yourself:

Does my artificial limb feel heavy and far away?

Do I find it hard to control my prosthesis?

Even though I have a light foot, is it hard to swing the prosthesis? 

IF YOU ANSWER ‘YES’ TO ANY OF THESE QUESTIONS, then may be the VGK-S is worth looking into, since it designed to address the special problems associated with a short femur. 



Frequently asked questions about VGK.

Q. With the VGK-Go!, what foot must I use?

A: The VGK has been designed to be compatible with any foot.  However, if a high heeled shoe is not accommodated for in the alignment of the foot, the joint stays in stance stability if the toe of the foot does not receive enough load due to the high heel. The VGK has been seen to be compatible with fluid controlled ankle devices with energy storing feet. It is important to avoid  a very soft a forefoot, as this hinders a proper forefoot loading.

It has been found that an energy storing foot both helps in further easing release into swing, and to help propel the shin into swing.

Q. My CPO says that a VGK is just another hydraulic joint. Is  that true?

A: False, NOT just another hydraulic joint! A VGK uses polykinetic control technology. Technology is the art of solving problems efficiently.  In fact, the polykinetic technology replaces the electrical sensors and on board computing, Polykinetic processing controls for variations in forces applied to the limb and variations in viscosity, and at the same time delivers state of the art functionalities!

Q. I like water sports, is there a problem if a VGK gets wet?

A: A VGK has been designed to withstand water and even shallow immersion (waist deep). If you need to get the joint wet on a regular basis, please  contact Orthomobility or your CPO so that a suitable service program can be arranged. However, a  VGK is NOT suitable for scuba diving or other such deep water activities deeper than 5 meter, for the risk of drowning: naturally the VGK is less than buoyant and like any other metal knee joint would not help to keep an individual afloat.

Q. I have not heard of  VGK before, who makes it and where can I get it?

A. The VGK has been developed by a Dutch CPO/MEng with extensive specialist experience in the UK NHS. Eighteen years of clinical and design experience supports the construction and fine detail of the VGK. The VGK is available through your CPO, who can contact us direct for advice regarding ordering. Alternatively you can contact us direct if you have other questions.