The Custom Fit Knee by OtisMed may Re...

The Custom Fit Knee by OtisMed may Result in Early Failures

Posted in the Knee Replacement Forum

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Philadelphia, PA

#1 Oct 24, 2007
The custom fit knee is considered by many surgeons to be a risky technology. It sacrifices alignment to attain balance. Although the claim is that motion is more like a normal knee because the cuts are custom...this couldn't be further from the truth. They cut the ACL, and use a knee with a uniaxial condyle, which is very unnatural. They also claim faster early recovery, however the actual data they show is no better than most surgeons. Someone may get on their case about false advertising.(For those of you who think the implant is custom...think again.)

My prediction is that over the next few years, we will see the early failures resulting from use of the custom fit knee. The malaligned knees will have early loosening, and also instability patterns. I think that surgeons using this should include a disclaimer that it is an experimental technology.

Philadelphia, PA

#2 Nov 24, 2007
I agree. Do you remember when the custom hips came out and everyone thought it was such an amazing advancement. A few years later all of those hips had to be redone as they failed. If this technology did more to preserve alignment, I think it might be interesting. But boy are these surgeons taking a risk trying this.
Interested Observer

Warminster, PA

#3 Nov 29, 2007
Dear Ortho MD, your nickname implies that you are an Orthopaedic trained medical doctor but judging by your comments I suspect this is not an accurate representation of yourself. You have an interesting, but misleading, take on the new technology of custom fit knees. And it is quite inaccurate. If, as you say, custom fit knees sacrifice alignment to attain balance (also known as stability) then it can only be concluded that the traditional approach to total knees sacrifices balance (stability) to attain alignment (an artificially induced alignment by the way, which in most cases does not match the patients normal anatomy). Despite what you have posted, the custom fit method actually does come much closer to replicating the motion of a normal knee than does the traditional method because it is based upon a patients true "MRI determined" flexion/extension and rotational axes. All total knee replacements remove at least the ACL so none will ever totally replicate the normal knee. The custom fit knee, however, is the closest method which current technology can provide to replicating a patient's original anatomic alignment. The claim of faster recovery is not only accurate, but is clearly being confirmed both in doctors offices across the country each day, as well as by the data in the current undergoing studies. It is true that the implanted device itself is not custom made. It is the process of identifying the patients natural anatomic alignment, and implanting the device into the proper matching anatomic position, unique to each patient, which is custom. As for your prediction of early failures due to malalignment and instability, there is no scientific basis to support that claim. Knees implanted using this technology are generally more stable than knees using the traditional method and since they more closely match the normal anatomic alignment of each individual patient, recovery is predictably easier and quicker. The actual results are proving this out. In knees implanted using the traditional method the device is implanted into the same predetermined alignment that every other patient gets, most often times with little consideration to their native anatomy. The soft tissue envelope is then modified through cutting and peeling away to accommodate the new leg alignment. Using the custom fit method the device is implanted in an alignment which closely matches each individual patient's natural anatomy. This negates the need for the majority of the soft tissue adjustment/disruption needed in the traditional method. The result is, predictably, a patient whose soft tissue (muscle/ligaments\tendons) is much happier with their post-operative alignment and therefore recovery is quicker, less painful, and more natural feeling.

Fort Wayne, IN

#4 Nov 30, 2007
To interested observer.

I have personally seen some xrays (I think they were from California, but not sure) of the results of the custom fit knee. A few of the tibias were in 6-10 degrees varus. One knee was in 1-2 degrees overall anatomic axis varus. One of the femoral components was in about 15 degrees flexion. I agree that small deviations from the mechanical axis probably do not matter. But Engh and Collier clearly showed that every 5 degrees that the knee is from the mechanical axis is the same as about 6 months to 1 year of poly shelf life.

I only saw like 7 xrays, and two of them showed separation between the poly and femoral component laterally (loose lateral compartment). I consider this instability, and would have advocated a medial release for better balance.

There is simply no substitute for intraoperative balancing. Of the 7 xrays I saw, 3 had objective evidence of either gross lateral gapping or gross mechanical axis malalignment.

And you say recovery is faster? Most fellowship trained surgeons can get a TKA discharge in 1 day, with ambulation sans cane at 10 days. Have you read the day stay TKA papers?...they were not depending on an MRI to make their cuts, were they?

To blindly follow the "cookie cutter" guide that some company has decided on is risky.

Surgeons using the OtisMed Custom Fit Knee should have there patients sign a disclaimer that the longterm results may not be as good as standard knee replacement.

This is a new experimental technique and should not be advertised to patients as an "advance" until there is proof that they do not fail early.

You can't argue that!

2nd Interested Observer

United States

#5 Dec 4, 2007
The basis of this system is that it puts the knee back into natural alignment. I thought an arthritic knee pretty much deviated from its natural alignment over the years due to arthritis, use, trauma and so on. What is natural now is not what was natural when the patient was 20. It just seems like it's based off of the same principles doctors used when using extension based tensor instruments to take the current balance of ligaments into play.

I would think I'd rather have my knee balanced based off of a mechanical axis as opposed to balanced to what it currently was after the years of arthritic changes have changed it from its natural alignment.
Big B

Clifton, NJ

#6 Jan 12, 2008
I have seen hundreds of knee replacements performed over the years, most with traditional alignment, many with navigation, and now a few dozen custom fit Otisknees. Have I seen any problems intraoperatively with the custom fit knees? Yeah, there's been a couple. But I've also seen PLENTY of intraoperative problems with both navigated and traditional alignment techniques as well.

I would refer to the other blog on this site titled "post operative knee pain" to give a realistic assessment BY PATIENTS what the complications are and how they are impacting people's lives. The reality is, there are a significant number of folks who have TKR's put in by traditional alignment who are living with real pain and problems out there.

From what I've seen and heard from several surgeons using the custom fit knees, they are reporting fewer problems post-op than what they had been used to, and there have been numerous instances where patients who got a custom fit knee say it feels "more natural" than the TKR on the other side that was done prior. I've also heard of questions being asked by physical therapists of surgeons using the custom fit knees to find out what they're doing differently, because the rehabs are going so much better.

Taken together, I believe that there is real promise with the custom fit technology. Is it perfect yet, or close to it? No. Can there be problems with it? Yes, but certainly no greater than using traditional alignment or navigation to this point. Has there been excellent outcomes reported, especially as compared with other methods? Yes, in a rapidly growing number as this technology expands.

We will see what happens, but it is well worthwhile to keep an open mind to this technology, and learn more about it. Then you can make up your own mind.

Philadelphia, PA

#7 Jan 13, 2008
Here is the first peer reviewed study on the custom fit knee, published in the Journal of Arthroplasty. The conclusion is that the Custom fit Knee results in poor knee alignment. Although the early results appear equal to traditional knee replacement, there is tremendous concern about early failures due to malalignment.

If you are a surgeon using this technology, and have not told your patients that it is experimental technology, you are at a legal risk. (%23toc%236846%232008%23999769 998%23677736%23FLA%23display%2 3Volume)&_cdi=6846&_so rt=d&_docanchor=&_ct=3 6&_acct=C000050221&_ve rsion=1&_urlVersion=0& _userid=10&md5=7f603841d24 5dfc64c1d9e061fe60022
Ortho Rep

Galveston, TX

#8 Jan 25, 2008
Granted, I am but a small minded orthopedic joint rep; here are my concerns with this product. What is the point of restoring a patients "natural rotation and alignment" with custom blocks, when all (as far as I know) total knee implants are designed with certain rotational and mechanical axis guidelines in mind. Putting a knee in according to "natural rotation and alignment" could theoretically place the implants outside their normal parameters and lead to early failure. Maybe it's these patients' "natural rotation and alignment" that led to their early arthritis, and a surgeon would want to put the knee back into that alignment? If your doing a total hip, the patients natural acetabulum may be in 55 degrees of abduction or higher. Should we calculate the patients actual abduction and anteversion in order to reproduce the actual alignment? I believe the current standard of care is to position the implants to optimize wear and stability (and of course leg length and offset), not to position the implants according to the patients natural, and possibly malformed, anatomy.

Fort Wayne, IN

#10 Feb 29, 2008
In my area, we are seeing a number of OtisMed knees requiring revision surgery (meaning redo surgery). It is a technology that passed through without FDA, IRB, or safety testing. Patients be careful.
Scared MDs

Piscataway, NJ

#11 Mar 10, 2008
You claim that traditional inst. are the way we all should be going yet what valgus angle do you set your distal resection at? 5 or 7 or how about 6 that’s in between. But is it even 6deg with a 10mm hole in the femur and a 8mm rod. Add a canal that can be anywhere up to 10-18 mm. in inner diameter. How about your 3 deg.s of external rotation how do you do that off deficient posterior cond.? Or is that your expert eye of the collateral ligament attachments. Lets talk tibia how do you set that position. Put a poly on a tray run thru a range of motion and mark it. Or maybe attach an alignment rod then move the foot under it till it lines up. Come on quit kidding yourselves. The way we have been doing it is not exact to what we think it is and yet we still have outstanding results. That shows the level of freedom we have to work with. I will also find the recent paper on 500 5-10 year out tka that show the ones outside 3mm of mechanical axis did better then the ones within. I understand you have invested a lot in your practice and navigation or whatever you’re being paid for but keep an open mind..

Philadelphia, PA

#12 Mar 11, 2008
To Scared MD.

I do enough joints in 1 year that I never have doubts about positioning... I used to, but now I am always on. On long film xrays, my tibial cuts are always within 2 degrees of what I shoot for. I also align the rotational axis quite well, and am within 2 degrees on my distal femur cut (which I vary depending on the patient). I am no longer a scared MD...because I have become very good at putting in TKAs.

The Custom Fit knee is an experiment on human subjects. This is such a departure from traditional knee surgery that it should be tested carefully before every random surgeon starts using it. It might work well. But what if these start failing early? What a disaster. It is wrong to tout this as an advance in TKA to the public, who doesn't realize that it is still in testing phases.

Trust me on this...I have a very open mind, I love new stuff..but you should see the xrays coming out of the custom fit knee surgeons...they are butchering their patients.

Portsmouth, NH

#13 Mar 15, 2008
In 12 days I will have a bilateral customfit tkr. I am convinced that this is the way to go for all the reasons outlined by Stephen Howell at the AAOS convention in March.See
But I am just a patient. I guess the biggest reason is that my Orthopedic Surgeon with 17 years experience and 15 of these replacements under his belt is convinced that this is the best way to do a tkr.

Philadelphia, PA

#14 Mar 16, 2008
Its funny that Bilateral John is a patient who knows all this Ortho specific a AAOS link and presentation name. My guess is he isn't a patient.

Los Angeles, CA

#15 Mar 17, 2008
Much of this technique assumes we should all throw out time tested and proven principles for long term success of knee arthroplasty. There have been paper after paper published from all over the world, which shows early failure with poor component alignment.
I would bet alot of my net worth that many of the posts on this topic which glamorize and tout this "custom" philosophy are posted by paid consultants. I would like to see Otis publicize how many stock options where granted to each of the physicians posted on their website.
The jury hasn't even left the court room on this debate. I am one who loves new technology and just finished my own training recently.. but I just don't see how adding another 1500 bucks for the blocks plus another 500 or so for the scan, to a procedure which already has little to no margin for a hospital can be helpful.

Portsmouth, NH

#16 Mar 18, 2008
Dear JointMan, your arguments all seem to be ad hominems. I am a patient who can read and trusts my surgeon. I will let you know how my operation goes when I get back to my computer in a few weeks. But wait, according to you I won't really know for seven years.

You are saying that the further the prosthesis is from 0 degree mechanical axis the more apt it is to result in premature failure? Isn't this the crux of the non ad hominem part of your arguement?

The dilema is that I need this operation now and I believe it really looks like it is head and shoulders ahead of the "artistic" "winging it in the clutch" that you do. Which incidently results in 10 to 15% of patients who complain of problems after surgery. Why do you go for a 0 degree mechanical axis that is only found in 2% of the population? Doesn't it make more sense to match the prosthesis to patients own healthy mechanical axis?

So pound your intramedullary rod up your patient's femur and engage in your brutal collateral ligament releases because mechanical axis of the posthesis doesn't balance as "naturally" as the custom fit.

My decision is to trust my surgeon and go with the arguements found in Stephen Howell's article that I cited above.

In regard to your longevity arguement I quote Howell:

Isn’t survivorship better when the mechanical axis is neutral?
No-new evidence suggest it is not! Only one publication has correlated postoperative
limb alignment assessed on full-length radiographs with survivorship
and those authors used a knee implant substantially different from modern designs
5. A recent study of 395 subjects with more modern knee implants
showed that outliers (i.e. > 3 degrees varus or valgus) had a BETTER 15 year
survivorship than those aligned in neutral.

To read the study check here:Parratte, S.; Trousdale, R.; Berry, D. J.; and Pagnano, M. W.: Reproducing
the Mechanical Axis did not Improve the 15-Year Survival of 398 Modern TKA.
In AAHKS. Edited, Dallas, TX, 2007

So my bet is with my own two knees, something more precious than a pay off from a medical company. I am putting my two knees on the line with full knowledge of the pros and cons of this new method. I have considered the non hominem parts of you arguements carefully and have decided to still go with the Otismed custom fit TKR and a Stryker Triathalon X3 posthesis.

Philadelphia, PA

#17 Mar 18, 2008
He is definitely not a patient...the words he is using reveals an intimate knowledge of knee replacement surgery....even the most educated, well read patients do not know details like this.

Bilateral trust a new technology, and let a surgeon (who has only done 15 of them) do this to you is outright stupidity. Congratulations, you are now officially part of an unmonitored human experiment.

Portsmouth, NH

#18 Mar 18, 2008
Oh, contraire mon ami, you flatter me.

I am a patient with an internet connection and a certain mechanical aptitude. Or do the Medical Priests all assume that they can scare us with fire and brimstome of a hell of pain because we don't follow the current "accepted party line" way of doing TKR.

This method is new but I won't concede that it is experimental. Yes, only 5000 have gone before me. But it makes theoretical mechanical sense that your concept of alignment is not correct. I refer you once again to Dr. Howell's article mentioned above. You can even get a DVD at a bargain for $50.00 they charge me $79: If I were doing these operations I would at least buy the dvd and see what the guy is saying before I attempted to scare the patients who are considering this approach.

How can you say that this "experiment" is unmonitored. You must know about Otismed's recently annnounced COMFORT registry.(Comprehensive Outcomes Measures for OtisKnee Replacement Technique).

the registry is expected to include thousands of patients at hundreds of hospitals across the United States. Data gathered in the COMFORT registry will be used to evaluate a variety of measures, including post-operative pain, range of motion, patient satisfaction and recovery rate as well as surgical time, operating room set-up time and cost, and hospital length of stay. All consented patient data will be gathered using the Knee Society Scoring System, the Oxford Knee Score and the widely utilized SF-12 scoring method.


Do you really think that I should wait 7 years untill all the evidence is in when I need the operation now and really think that this new approach to TKR is sound and makes sense for me.

The most cogent part of your arguement is that this approach is too new. This is why I trusted my surgeon who reccomends this proceure but also personally did all this research to make damn sure he had some good evidence behind his reccomendation.

Santa Barbara, CA

#19 Mar 19, 2008
Hello I am going in for an arthroscopic/documentation of my knee. I do not have alot of arthritis but I have bone OCD lesion. Being 52 and a formally active man I was wondering if this new device would be a better direction. I live in Southern Calif. Thanks, mike

Portsmouth, NH

#20 Mar 20, 2008
TKR...Total Knee Replacement is the absolute last resort. You have to try a whole bunch of less invasive, extreme, solutions than the total replacement of your knee joint with a titanium and plastic prosthesis.

If after exhausting every other alternative your carefully selected and trusted orthopedic surgeon recommends a TKR then he will have his favorite specific prosthesis and surgical method of inserting it into your body.

If you have any doubts about how extreme this operation is I suggest that you watch a couple videos of the operation online on youtube.

This discussion thread contains a debate about a new method that was developed by a Surgeon in California named Stephen Howell.

I find it at times humorous and freightening that the surgeons on this site accuse each other of being bribed by different companies to use a particular prosthesis and method of insertion.

You also have to appreciate that some of them are fighting over turf.

But to put things in perspective don't forget that the Otismed CustomFit TKR has only been done on 5000 knees and the other older method at least a half million knees a year.

I go in next week for mine. I wish it were yesterday.

Caveat Emptor!

Philadelphia, PA

#21 Mar 23, 2008
Bilateral John,

I respect your opinion, but frankly you are wrong.

#1) Otismed claims a faster recovery because of the reduced need for ligament releases. FACT: most experienced joint surgeons seldom release a ligament. Its not that hard to get the cuts right.

#2) Otismed claims natural motion. FACT: Your ACL is still cut, the implant has a fixed radius (unlike the natural knee), and the implant's sagital curve does not match your own. This is incompatible with normal motion.

#3) Otismed claims an advantage to avoiding intramedullary instruments. FACT: multiple papers at this year's AAOS showed no clinical difference between intramedullary and extramedullary devices.

#4) Otismed claims a faster recovery. Fact: there description of a fast recovery is not that impressive, and is actually inferior to surgeons using rapid recovery protocols. Many of my patients go home the same day and are walking without a cane at 6 days.

#5) Fact: In my area we have already seen the consequences of the Otis results. Unbalanced knees that are poorly aligned. Many of the most experienced surgeons have abandoned the Otisknee after trying 5-10 cases. In my area, the surgeons still using it are the ones who were never good at joint replacement surgery and need the cutting jigs to help.

You are a victim of good advertising and a video at the AAOS..of 1 patient.

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