Conformis knee replacement

Knee replacement is a method of taking out the old and damaged knee joint and replacing it with a new and artificial one. Conformis is one method of doing this, it is the latest and most modern development of the basic technique.

Parts of the human body still haven't quite adapted to this walking upright change and the knees, along with parts of the blood circulation in the legs and so on, are prime candidates for not having quite caught up. The pressure of the full body weight leaves them prey to osteoarthritis, among other problems.

The cure, the treatment, for this problem is to replace the moving parts of the knee joint. The Conformis knee replacement uses the latest in scans and diagnosis combined with modern metal fabrication techniques to produce that replacement knee.

Specifically, complete scans enable the design of parts that mimic the original knee rather than shoehorn a standard part into a variable space. 3-D printing techniques allow the production of metal parts that exactly meet and suit those scanned designs. The end result of the Conformis process is a replacement knee that is as close as is possible to the original that is being replaced.

The advantage here is that there is already some decades experience in how the specific knee works. By replacing with something that copies in detail, rather than some standard part shaped to fit, all of that implicit knowledge already earned by the patient is still relevant. It can be thought of as the difference between having a new knee and a different one.

There are a number of things that can go wrong with knees. They're not a perfectly designed joint. Tendons can stretch or break, as with the anterior cruciate ligament. There can be problems with other ligaments, failing to hold matters together properly. The meniscus can be damaged.

A common enough problem is the development of arthritis, more properly osteoarthritis. It is this arthritis which is treated with a knee replacement. The other problems have other treatments. Osteoarthritis itself is when the protective cartilage that protects the end of the bone wears away or breaks down for some reason.

This can leave bone against bone, leaving the joint working about as well as an engine without oil or lubrication. It is this which leads to the stiffness, difficulty in movement and, of course, pain. The solution is to mechanically replace the two sides of the joint – here the knee – and the cartilage in-between.

To determine whether a Conformis knee replacement is required, it is necessary to walk through the diagnostic pathway. Why is the knee locking, or sore, or giving away? Pain in the knee, as with those other symptoms, can have a number of causes.

Once it is determined that osteoarthritis is the specific cause in this case, then a further series of actions. Perhaps simple management of the condition will be enough. Preservation of the current situation might be possible.

At the end of this process, then the knee replacement itself becomes the necessary treatment. The necessary precondition for a Conformis knee replacement is that osteoarthritis is causing significant limitations in the operation of the knee.

A knee replacement is significant surgery. It involves, at minimum, attaching new ends to both bones and the connection of the joint between them. The Conformis system does this by first working on designing the specific replacement for the specific knee.

Everyone is just that little different, and this is true of joints as well as other body parts. Other knee replacement systems use standard parts. It is the remaining part of the knee that is then adjusted to fit. The Conformis system starts with significant scanning of the extant knee.

It then designs the one specific set of parts to replace it. These are then built using 3-D printing – to go with the 3-D scans – to produce parts which fit, exactly, the existing bones and knee presentation. Each knee design is different, each knee is built to order to that specific design.

This can also be said as the Conformis mirrors the original anatomy rather than altering it to fit the parts available. This design and manufacturing process will take perhaps 6 weeks, possibly two months. An immediate operation using Conformis is not possible.

Once the custom-made Conformis knee is available the replacement is significant surgery. There will be a general anaesthetic followed by several days in hospital. All the usual surgical restrictions will be in place, nil by mouth from the day before and so on.

There are alternatives, including much heralded robot surgery and so on. These involve more invasive work and also fail to be specifically designed to suit the extant anatomy. The end results with Conformis lead to better performance up and down stairs and when twisting.

The Conformis knee replacement is significant surgery. It will be followed by a recovery period from general anaesthetic and a couple to several days in hospital.  There will be bruising and swelling in the period following the operation. These will take some weeks to fade.

There will also be an increased temperature around the joint, this comes from the increased blood supply to it. The stitches used are self-dissolving, so a further procedure to remove them is not required. It is possible to start walking near immediately, soon after awakening.

A certain effort is required in the first days and months in order to loosen the stiffness of the new joint. This effort is worth it and the final performance improves with that work done. The final performance will also be better than the alternative knee replacements available. 

Driving will not be possible immediately – it is banned for 24 hours after a general anaesthetic anyway. There is no set time when the knee will be ready again. The actual test is more psychological than physical. Sit in the car and attempt an emergency stop – while stationary of course.

If there is hesitation in using the knee, then driving is not yet to be allowed. Fixing one knee has the tendency to cause such hesitation in both. This effect can take anywhere from 2 to 6 weeks to fade and is accelerated by more exercise and use of the new joint.

All surgery carries risks and Conformis, like any knee replacement, is no different. These will include the possibilities – low, perhaps 1% - of blood clots, infection, nerve damage and so on, common to all surgical procedures.

There will be pain, and pain management today is extremely effective and entirely modifiable. Worries have been expressed about nickel sensitivity as that metal is in the alloy used. Such an allergy does exist, but nickel sensitivity is a contact dermatitis, something specific to the skin, not a general allergy by the entire anatomy.

There is no skin in a knee, thus there are no such allergenic concerns. The biggest risk is that the new knee will wear out over time. For all knee replacements, this happens perhaps one time in five by the time 20 years has passed.

Conformis is a new technology, therefore there isn't a 20-year record to examine. But at the 5-year mark, which can currently be measured, the performance is as good as, the failure rate less bad than, the alternatives at the same stage.