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

4 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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    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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    All the private hospitals, that we work with, have international accreditations. This requirement ensures that our patients will always receive their surgery in the best possible conditions, very similar to what can be found in North America and Western Europe.

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