Patellar Clunk Syndrome: Complication Following Knee Replacement Surgery

In general, (TKR) is a highly successful procedure. However, complications, although relatively rare, can sometimes occur. One such complication is known as .

To understand this condition, it helps to first understand a little bit about knee anatomy and function (Figure 1). During knee flexion and extension, the patella (knee-cap) rides within a groove in the femur (thigh bone).

Knee Anatomy

Figure 1: Basic Knee Anatomy

In knee replacement the worn ends of the bones are “resurfaced” with metal and plastic implants. The patellar groove is part of the metal femoral component that is implanted onto the prepared femur during the total knee replacement procedure. At the end of this groove there is a transition between the metallic implant and the native bony surface.

Following knee replacement, scar tissue can sometimes form at the top or “superior pole” of the patella. During particularly deep flexion, this scar tissue may move below the end of the groove in the femoral component and then “catch” on the end of the groove as the patella moves back with knee extension. It is this catching and then forceful release with extension that results in the “clunk” and pain characteristic of this condition.

This condition is more prevalent in a type of knee replacement known as Posterior Stabilized, or “PS” knee replacement, although it has also been reported in Cruciate Retaining (CR) knee designs as well. 1 In PS knee designs, where the posterior cruciate ligament is removed, the patellar groove tends to be shorter to avoid contact (in extension) between the end of the groove and a plastic post on the tibial component found in these types of designs. Consequently, the patella can come off the end of the groove during lesser degrees of flexion.

The publication cited at the end of this article provides more detailed information and a review of some of the literature on patellar clunk.

1 Niikura T, Tsumura N, Tsujimoto K, Yoshiya S, Jurosaka M, Shiba R. Patellar Clunk Syndrome After TKA with Cruciate Retaining Design: A Report of Two Cases. Orthopedics. 2008: 31:90

Comments

13 Responses to “Patellar Clunk Syndrome: Complication Following Knee Replacement Surgery”

  1. rajoo6 on April 27th, 2009 11:21 am

    nice and impressive presentation. cheers!

  2. Penny ODonnell on June 5th, 2009 4:39 pm

    So how is patellar clink syndrom diagnosed and what is the treatment for it?

    I had TKAs three months ago, and for most of the time since then I have sharp pain whenever my right knee is released after it has been flexed. A typical scenario is sitting in a chair with my foot under me on the floor. When I move my foot forward extending the knee there is sharp pain, a catching feeling.

  3. Karen DeWitt on August 2nd, 2009 4:34 am

    I am now 9 days from my bilateral lesser invasive knee replacement surgery and so far I must say it has been a great experience. I am turning 50 this year and was dealt some bad genes, family history of osteo arthritis. I have also been a very active athlete my entire life. The most difficult thing was being confident that now was the time to do the surgery. My surgeon said that in light of how long knees last now (about 22 years) I should not wait until I am suffering. Although I have continued to work out up to the date of surgery (swim, weight train, eliptical machine, biking and spinning classes) I have not been able to run, golf, and play other sports I always enjoyed for more than 8 years. Over the past year, stairs and walking became more and more painful and as I worked out I could feel there was very little, if any cartilidge remaining in my joints. I am thankful that I keep my legs strong and did all I could to stay physically active, I feel this has been critical to my quick recovery. After surgery my doctor did say that there was next to nothing left of my patella and that the joint was bone on bone. I know if I had not been in such good physical condition I would have felt much more negative affects of my arthritis. Today, 9 days post surgery, I am walking slowly, but can do so without a cane. I already am at 95 degrees flex and 6 degree to straight. My doctor uses a lesser invasive technique, this was also critical to a speedy recovery. My doctor said when all is said and done I will have no restrictions and should be able to enjoy the sports I have been missing over the past decade. More importantly I will not have pain as I walk and go about my daily living.

    I would like to encourage other people out there to work to keep your legs strong, this will always help you continue to function on a daily bases as well as feel fewer affects of your arthritis. Weight train, swim, cycle. Secondly, consider lesser invasive or minimally invasive total knee replacement surgery. I chose bilateral because I was physically fit and I did not want to spend two summers recovery and returning to all the things I have missed. I would do bilateral all over again. Thanks to my surgeon I am on my way back to an active life style!!

  4. Brian Gregory on September 1st, 2009 7:39 am

    Greetings,

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    One of the viable alternatives have been to get surgery done abroad. In fact, the price drop can be as much as 70 to 80%, when having your surgery performed in Morocco, while keeping a high standard of quality of care.

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    Meet our orthopedic surgeon, Dr Ali El Kohen, his international experience encompasses practice in Insall Scott Kelly Institute for Orthopaedics at Beth Israel Medical in New York as well as an AO-Fellowship at the Harvard Medical School.

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  5. John Reeves on April 16th, 2010 2:56 pm

    I had TKR 10 weeks ago and have had clunking whilst walking from the beginning but its been getting slowly worse. Its now audible. I return to see the consultant in coming weeks (NHS timescales). Is there a likelyhood of needing the patella (re)-lining. Is it keyhole surgery. What else might it be? I dont fancy major surgery again – the recovery was hell. I wish I’d kept the old knee.

    Thanks in advance for any feedback.

  6. gayle helms on June 24th, 2010 7:03 pm

    Hi my name is gayle helms.and Im looking for some help to understand more about petalla clunk syndrome.Is it caused due to surgical error or5 what I have been so miss lead about whats wrong with my new knee I am totaly confused .Iv been to several different doctors since I developed this problem and no one would tell me whats realy wrong with it only that I had to choses I could have it operated on or live with the pain,until i call one doctors office and talked with a doctors assistant who exaimaided me almost a year earlier and told me I had ben diagnosed with petalla clunk syndrome and that was the first time any one actully told me what was in fact wrong with my new knee. the knee cap showes to be tilted and rubbing on the prostieses. I also need to know what its going to take to fix it

  7. John Reeves on July 2nd, 2010 2:04 pm

    You have my sympathy Gayle. Have you had the clunking from the beginning? I have, and am still being told by the NHS consultant that it is normal. I am going to get a formal 2nd opinion from a private knee expert. I believe something was not done correctlly in the operation – possibly a misalignment.

    Anyway, Gayle, I believe the clunk syndrome happens for some people after the prosthesis has been in for quite a while, not from day 1 after the operation. For normal syndrome sufferers, the bone starts to overgrow the prosthesis, over time, making a ’spur’ which then rubs on the patella – hence the clunk. The normal clunk syndrome does not apply to new TKRs – that’s why I’m not happy.

    Good Luck. I’ll write again once I’ve had my expert opinion.

    Cheers, John

  8. Dawn on August 3rd, 2010 5:00 pm

    For those who are experiencing “patella clunk syndrome” it does not mean that there is something wrong. This is just the normal wear on these types of components. Some people may be bothered by this more than others but almost all of us will experience this and some will have pain and some will not.

    I had to have a total replacement due to the surgeons mal-practice. The first time around, it clunked so hard that I thought others could hear it. The first prostehsis was an older model which weighed about twice as much as the newer models of today. It also contained high amounts of nickel to which I am very allergic to and it was too big for the space in my knee which resulted in him removing more tissue than he should have – I now have a big indenture above my knee that should not be there.

    I still have a “clicking” but for the most part, I hardly notice it all. Maybe it’s because the first one was bad that it makes this seem like nothing.

    Talk with your surgeon about this, express your anxiety and if you do feel like you are getting the right answer, make an appointment with another surgeon who specializes in these types of procedures.

    Just remember, it can take up to a year before you are fully recovered.

    Dawn

  9. JAYNE HANSON on August 10th, 2010 3:44 pm

    FOURTEEN MONTHS AGO I HAD TKR – WAS DILIGENT ABOUT THERAPY AND NOW AM AT 150 DEGREES – FOR TWO MONTHS IT WAS ALL UPHILL WITH THE RECOVERY – THEN ONE DAY I WAS DOING A GOOD DEAL OF WALKING SO I USED AN ELASTIC SLEEVE ON MY KNEE – THAT NIGHT I HAD SEVERE PAIN AND SINCE THEN HAVE A ‘VERY TIGHT KNEE’ MOST OF THE TIME AND CAN’T WALK MORE THAN AROUND THE BLOCK WITHOUT THE ‘SLEEVE’ – MY KNEE OVERHEATS AND I HAVE PAIN UNDER THE KNEE AS WELL AS ON EITHER SIDE – IT VARIES. VEINS IN THE KNEE RISE TO THE SURFACE AS WELL AS IN OTHER PARTS OF MY LEG SINCE THE SURGERY – I HAVE NERVE PINCHING AS WELL – COULD THIS BE A MISALIGNED PATELLA?

  10. John Reeves on August 16th, 2010 8:43 am

    Good advice Dawn; I hope your new joint turns out OK. I suggest you get immediate expert attention Jayne. It doesnt sound good. Good luck to you both.

    I’ve just had a private 2nd opinion closely followed by another chat with the surgeon. They say my cluncking is from soft tissue catching on the prothesis. It is therfore not what I feared, ie a fault with the prothesis. I am reassured because it may go off slowly and it means I wont need to have major surgery to fix it. If I do want to be rid of it, I could have the patella resurfaced but I am advised this may produce futher issues! So, I have decided to see how the next 3/6 months goes.

    I have found something interesting. It seems opinion is divided amongst surgeons about resurfacing the patella at the same time as doing a TKR. Via google, I found this http://www.wheelessonline.com/ortho/indications_patella_resurfacing1.
    This suggests it should be done with the TKR to allevaite pain and improve stair climbing – no mention of clunking though.

  11. admin on August 17th, 2010 1:57 am

    Hello Dawn,

    Thank you for your comment and perspective. I did want to clarify something on patellar clunk.

    Although there may be some benign “clicking or clunking” and total knee components do wear over time, patella clunk syndrome is not related to implant wear. In some patients excessive scar tissue can form at the top of the patella and this scar tissue can catch on a certain part of the implant component that is placed on the femur (thigh bone). The tendency for this scar tissue to catch on the implant can be influenced by implant design and placement of the implant on the bone by the surgeon (that is, poor design or misalignment of the implant can increase the likelihood of patella clunk syndrome in patients that are prone to excessive scarring.).

    I hope you have found this information helpful.

    Regards,

    Admin at totalkneeweb.com

  12. admin on August 17th, 2010 2:07 am

    John Reeves,

    Thank you for your comments and sharing your experience and perspective. Some years ago, I recall that leaving the native patella in place with knee replacement was more common in European countries than in the USA, where the patella was mostly resurfaced. From the reference you cited, it appears that resurfacing the patella is more the norm these days regardless of location.

    Please feel free to visit the forum on this site and begin a topic or leave a comment there…It may be more “user-friendly” with respect to conversing with other visitors than the comment section here, but feel free to post where you wish.

    Thanks again,

    Admin at totalkneeweb.com

  13. John Reeves on August 18th, 2010 6:55 pm

    Thanks Admin.

    My clunking was from day 1; hence my worry over ‘bad’ engineering/fitting and my entries on this forum on April 16, July 2 and Aug 16 above.

    Regards,

    John, age 61, UK

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