Kinematic Alignment is the technique where the anatomical position of the knee replacement is matched to a patients own anatomy. This means that the alignment for each and every person is unique - even the alignment between two knees on the same person! The technique is not new, and has been tried and tested and studied for over 2 decades. The technique is coupled with a medial pivot designed implant with the aim of providing amazing function, no pain, and a higher level of functional capabilities than ever before. Please watch, and feel free to ask questions on our YouTube channel, or Facebook page. We will answer them below
Implant Materials and Composition
All of our knee replacements are Cobalt Chromium. The plastic is a highly specialised polyethylene. The composition of the implant is designed to increase longevity. Under an electron microscope, the surface of a CoBalt Chromium implant is extremely smooth. In a knee replacement, there is no metal touching metal, as the plastic sits between it.
For more information of knee replacement composition - visit this link.
Dr Chien-Wen Liew explains kinematic alignment in knee replacement and how it differs from conventional mechanical alignment.
Read transcript
0:00 · Start
Hi, I'm Dr Chien-Wen Liew from Adelaide, South Australia. I work at Orthopaedics 360 and today I'd love to talk to you a little bit about kinematic alignment for the knee.
0:20 · What I do everyday
I'm a dedicated hip and knee replacement specialist and don't do anything else. So today, I thought it would be important for me to talk about one of the techniques that I'm most passionate about, and that is kinematic alignment for the knee. Now, kinematic alignment is something that, although it hasn't been in the mainstream orthopaedics recently, it's not a new technique. It was spawned about two decades ago.
And certainly, it has risen to be one of the more prevalent methods, and certainly one of the more controversial and discussed methods in recent times.
0:51 · My experience with Kinematic Alignment
I have been placing all of my knee replacements with a kinematic alignment for many years and feel that the philosophy behind it is something that resonates with me and my patients.
1:02 · Key difference between Mechanical and Kinematic alignment
The key difference between a conventional method and a kinematic alignment is one where we place the knee to match the patient's native anatomy. Now, this is something that we probably need to take a few steps back from. And I'll go through how I used to perform a knee replacement prior to kinematic alignment with a standard technique.
1:23 · A Non Kinematically Aligned Knee (Conventional technique)
What we aim to do with all of our knee replacements was placed, every knee replacement the same as the next person. Which meant we were trying to obtain a straight line from the hip, through the centre of the knee, through the centre of the ankle. That made 180 degrees, therefore, making every single person's leg perfectly straight. We would also opt to place a foot progression angle now you may see people walking with a bit more of a duck footed position or pigeon toe.
That is the foot progression angle now, with a full progression angle of 10 degrees. That was found to be one of the most common foot progression angles in the community. And when we plot a bell-shaped curve of all of the alignments for all of the angles of the knee, we find that the centre point of that bell-shaped curve, or very close to it, replicates our aiming point for a standard knee replacement.
2:23 · Learning by watching nature
Now, if we look around at people walking on the street, we can see lots of people walking with bow legs, knock knees, duck feet and pigeon toes. And actually, most of those patients will not have knee osteoarthritis now, as a knee degenerates, we certainly know that you will find that the knee will change some of the angles that it has. That being on the frontal plane, where we look at a knee from the front, on the side, and also in rotation.
And that can give a knee more of a bow-legged appearance, more of a knock knee appearance, or could change the foot progression angle of the leg as well. Now, as part of that angulation deformity, we look at how that occurs.
3:04 · Angulation differences in knees
And in general, almost all of it occurs due to the loss of cartilage in a particular spot, more than any other spot of the knee. Now, when we're looking at a knee x-ray, we can certainly identify on that one view, at that one angle, what that angular deformity is, and in general, we obtain angles of the knee at 90 degrees to one another. In this method,
3:28 · What is kinematic alignment for TKR
we're looking at performing every knee replacement to match the angles of the knee on 360 degrees around the knee, meaning that we're obtaining measurements of the knee. To give us all of the angular differences between patient to patient that we need to apply during surgery, this is kinematic alignment. Kinematic alignment aims to replicate the patient's native anatomy on all of the angular changes that patient has from when their knee was normal.
And what we're doing is we're not just putting the knee back to where it was when the knee is arthritic. But we're changing it back to the position of what a patient's knee was before they had any underlying arthritis. When we've changed someone's anatomy and we're placing it in a position that they are not born with or used to, we have to make releases, changes and alterations to balance a need.
As part of the technique of a standard knee replacement, we used to have to learn a sequence of releases of the ligaments, tendons and capsular structures around the knee. That enabled us to balance the knee effectively and give someone a well-balanced, good stability knee with kinematic alignment.
4:46 · Our aim with a kinematically aligned knee
We aim not to damage any of those ligaments, tendons and capsular structures, we aim to place the knee replacement. Of how that patient was made and how that patient lived their life before they had arthritis, this means that the ligaments, tendons and capsular structures are left intact. Now, there are obviously some exceptions to that rule.
5:11 · Exceptions to the Kinematic principle
The first exception that comes to mind is are patients with severe patellofemoral osteoarthritis, where sometimes some releases need to be made to bring the patella back to its native position. Now, if a patient has lived their whole life with a knee that has been very unusual or anatomically altered, we would aim to position that knee in a different way, to match a more synergistic way for the patella to track.
Additionally, patients who have had or undergone surgery for their ligaments, especially the collateral ligaments around the knee, or have had a bony procedure, such as a higher tibial osteotomy, may require changes to this plant. But if we're looking at the stock standard knee replacement for 95 percent of the population, we are aiming to leave you in the same position that you were born with.
6:04 · What will your knee end up looking like after Kinematic TKR
So this means that for our patient who has bow legs, who got more bowed from their arthritis. Instead of bringing them back to be perfectly straight, we will bring them back to their original position of how that knee looked when they were 20 years old. Now, whilst you may think that, you might notice these angular changes, we find that our patients who have lived their whole life with slightly bow legs or slightly knocked knees.
Some patients notice their leg looks straighter after surgery. And that sometimes is far from the truth, as we have just matched it to how they were born. It's a technique that resonates very much with me. With our philosophy being to keep as much of the soft tissue intact and to not damage or release any of the ligaments, tendons or muscles unless absolutely necessary.
And it's something that I feel has given our patients the result that they're looking for. I hope that you found this video about kinematic alignment for knee replacements useful.
If you wish to learn a little bit more, please don't hesitate to subscribe or like this video and certainly follow us on YouTube and Facebook. Thank you very much.
Transcript edited lightly for readability.
How a Normal Knee Moves
Unlike a standard hinge, a normal knee bends, straightens, opens and closes (laterally), is tighter medially, and also rotates. This is what the implant design is for - the medial pivot design mimics the behaviour of a normal knee. When coupled with kinematic alignment, this is designed to increase the natural feeling of a knee. To achieve kinematic alignment, patient specific technology is used. For all of our total knee replacements, a disposable instrument set is used so it is brand new for each and every knee that is performed.
Preserving Ligaments and Soft Tissue
Yes, the aim of a kinematically aligned knee is to not cut or detach any of the surrounding ligaments, tendons or capsular structures. Like with all knee replacements with a medial pivot design, the ACL and PCL, which reside within the knee, are removed, in order to position the prosthesis. The surrounding ligaments, the LCL and MCL, including the Popliteus, ITB and capsular structures are not damaged or released.
Kinematic vs Mechanical Alignment — What Is the Difference?
Mechanical alignment was developed in the era of the earliest knee implant designs. The goal is a straight leg: the bone cuts are made perpendicular to the mechanical axis of the limb, so that the hip, knee and ankle line up at 180 degrees. Every knee is prepared to the same target, regardless of what that person's knee looked like before arthritis. Because most people's joint lines are not naturally perpendicular to this axis, achieving the target frequently requires releasing or lengthening the surrounding ligaments to make the knee balance around the new, altered joint line.
Kinematic alignment takes the opposite starting point. Rather than imposing a single universal target, it asks: where was this patient's joint line before arthritis wore it away? The bone cuts then reproduce that pre-arthritic geometry, resurfacing the knee to its own constitutional alignment. The natural obliquity of the joint line is preserved, the ligaments remain at their native tension, and releases are minimised or avoided altogether.
In practical terms, the differences are these. Target: mechanical alignment aims for a neutral 180-degree axis for everyone; kinematic alignment restores each patient's own pre-arthritic anatomy. Joint line: altered in mechanical alignment; preserved in kinematic alignment. Soft tissue: mechanical alignment often requires ligament releases to balance the knee; kinematic alignment works with the ligaments as they are. Consistency: mechanical alignment treats every knee the same; kinematic alignment treats every knee — even the left and right knee of the same person — as unique.
Mechanical alignment asks every knee to fit one target. Kinematic alignment asks the implant to fit the knee — restoring the joint line each patient had before arthritis changed it.
Dr Chien-Wen Liew — Orthopaedic Surgeon, AdelaideNeither technique is "new". Mechanical alignment has the longest track record and remains widely used. Kinematic alignment has now been studied for more than two decades, and published survivorship studies at 10 to 15 years report comparable implant survival between the two approaches. The registry data available so far does not show a longevity penalty for kinematic alignment, while proponents report a more natural-feeling knee in appropriately selected patients. It is a factual difference in philosophy: one standardises the limb, the other individualises the implant position.
Who Is Kinematic Alignment Suitable For?
Kinematic alignment is suitable for the majority of patients undergoing total knee replacement. Patient selection still matters. Those with significant pre-existing deformity, prior fracture malunion, or ligament instability may be better served by a more conventional alignment strategy, or a hybrid of the two.
This is why every knee in my practice is assessed with a 3-dimensional scan before surgery. The patient-specific planning process simulates the surgery in a 3D environment first, confirms the intended alignment is safe for that individual anatomy, and produces cutting guides manufactured for that patient alone. The decision between kinematic and conventional alignment is made deliberately, before the operation, based on each patient's imaging — not as a default applied to everyone.
Does Alignment Affect How Long a Knee Replacement Lasts?
Published studies following kinematically aligned knee replacements over 10 to 15 years report survivorship comparable to mechanically aligned replacements. Longevity of any knee replacement depends on multiple factors — implant design and materials, fixation, infection prevention, patient weight and activity, and surgical accuracy — rather than alignment philosophy alone.
For the full Australian registry picture — survivorship at 15 and 20 years, the main causes of revision, and which patient factors change the risk profile — see the companion article on the longevity of a total knee replacement.
Orthopaedic Surgeon, Adelaide
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