A Guide to Knee Brace Hinges
Choosing the correct knee brace can be a difficult process, with a lot of technical language and five different types of hinges available on braces, its understandable to need some guidance on choosing the correct knee brace.
With five different hinges, some guidance is also needed to learn exactly what benefits and levels of support each hinge provides.
Pot Rivet Hinge
A pot rivet is the simplest hinge. They feature one or more points of pivots but are restricted to 180 degrees of vertical movement and do not bow horizontally meaning any twisting or unnatural movement is prevented.
The two hinges are not connected meaning that they work independently offering support for the knee, but they do not offload any of the pressure away from the joint.
They simply support and correct the knees natural movement, making it an ideal choice for supporting a general imbalance or weak joint.
The construction of this hinge is identical to the pot rivet hinge, with the only difference being that a triaxial/three-point hinge features three points of pivot.
Giving it a slightly more natural movement than the pot rivet hinge meaning that it will feel less restrictive whilst essentially offering the same level of support to the joint.
This type of hinge will generally only allow 180 degrees of movement, meaning if you have suffered from hyper extension where it gives way when it is fully straight or goes past being straight, a hinge with a definite end point is the correct brace for you.
Non-axial leaf springs work differently to a conventional hinge, it is formed using sandwiched layers of metal and plastic which can freely blend vertically forward and backwards at any point but will not bend side to side.
Making them extremely popular as they do not feel restrictive but do keep the knee straight, the springing action gives the feeling of pushing the knee and helping to complete a step.
The only downside of this free movement forward and back is that with not being limited to the 180-degree natural movement of the knee, so it will not prevent hyper extension of the knee in a forward motion.
Braces with this type of hinge are therefore suitable for use on knees with medial or lateral weakness, which would make the knee prone to collapsing inwards or outwards and hyper extension is not an issue.
The non-axial leaf spring hinge is unique to the push braces, these braces are perfect for everyday use or during low impact sports such as jogging or golf.
Offloading or Geared Hinges
Offloading hinges have just one point of pivot around a gear mechanism, meaning both sides work in tandem with each other.
It is this connection between the gears that causes weight to offload from the knee through the hinge where it is then dispersed through the thigh and calf muscles.
The offloading hinge provides a higher level of support than a triaxial hinges, however the movement does not feel as natural meaning some people find this restrictive.
An offloading hinge is recommended to anyone suffering a high-level ligament injury, as the offloading hinge will keep the knee in line and prevent bowing, twisting, hyper extension or any other unnatural movement.
The rigidity of an offloading hinge makes it ideal for higher impact sports such as skiing.
A Fourcepoint is a type of hinge unique to the Donjoy range, the Fourcepoint hinge gives an offloading effect to similar to the offloading effect.
When you straighten out a Fourcepoint hinge, rather than fully extending to 180 degrees straight away, this hinge slows and softens for the final part of the movement, providing a cushioning effect through the joint.
It achieves this through a combination of geared hinges and springs, this softening action can be set to come into effect at different stages of extension, depending on which level is selected.
The hinge is designed to never quite reach the full 180-degree extension, this prevents the knee from locking in a straight position.
The Fourcepoint has the additional feature of being able to adjust the angle to which the knee can be bent by inserting flexion stops, they can be set at 90, 75, 60 and 45 degrees making this an ideal alternative to NHS braces post-surgery or treatment, as the brace can be adjusted to your stage of rehabilitation.
This hinge provides maximum relief to the joint, and for that reason it is recommended for high impact sports such as skiing and motocross.