Trochleoplasty – The arthroscopic version – Eng

This page is about the Trochleoplasty or Grooveplasty operation. This surgery deepen the groove in which the kneecap glides. The surgery can be done by arthroscopic technique a technique with some obvious advantages.


First of all sorry for this awful word trochleoplasty, however there is no simple word to better explain it. Maybe Grooveplasty would be a better term - if you have a better suggestion please do not hesitate to contact me. Trochleoplasty is a surgery for the Trochlear groove, a groove that helps the kneecap (the Patella) to stay in place. By this surgery a new and a deeper groove is created to normalize your anatomy. If you just want to know why it is so obvious to have it done by the arthroscopic technique you need to jump down to Why?.

Why am I going to have a groove operation?

If you are troubled by unstable kneecap or chronic anterior knee pain, you might also have an abnormal groove. This means that the groove for your kneecap is more shallow than normal or it can be even flat or convex. In short, when your knee groove is too shallow, this tends to make you kneecap unstable. It basically means that it might either go half the way out (called subluxation) or it even dislocate. The condition of having a shallow groove is called trochlear dysplasia or dysplastic trochlea (abnormal groove). In these cases were you groove is flat, this operation called trochleoplasty, is the best option for you.

If you have a shallow groove

We know when your groove is shallow or flat, it is a result of too much bone in the center of the groove. This basically means that you have too little bony support for the kneecap. 

The Surgery 

The principle of the groove surgery is basically to deepen the groove. First is the cartilage released from the groove. Subsequently excessive bone is removed. This is followed by creation of an outer bony wall to support the patella. After that, when the groove has been deepened and re-shaped, the cartilage is re-located by means of a special blue or white bands. Those tapes or bands are later resolved. You can find picture examples by the images below. Certainly the groove operation is, from a mechanical point of view, the most anatomically correct operation to perform, if you have an abnormal groove.


After having invented the technique, I started out in 2008 doing the first arthroscopic deepening trochleoplasty procedures. I used to do the groove procedure openly by the Bereiter method. I have stopped to do the open surgery. The open trochleoplasty method leaves a bigger scar, and in addition it is more painful and the risk of scar formation arthrofibrosis is 30%. My experience tells me that I can obtain far better results by doing it by arthroscopic technique.  In the past year three studies from other international groups embraced the arthroscopic deepening trochleoplasty technique. They demonstrate comparable result to our three previous publications.

More about the groove surgery

By using the pinhole technique (arthroscopic), consequently the surgery becomes less traumatic for your knee , and therefore the rehabilitation is likely to become accelerated. To notice is the groove operation mostly done in combination with a reconstruction of the inner ligament for the kneecap (MPFL reconstruction). Even the most severe cases of trochlear dysplasia can be operated by arthroscopic deepening trochleoplasty.

Why go for arthroscopic trochleoplasty instead of open trochleoplasty?

By using the pinhole technique (arthroscopic), consequently the surgery becomes less traumatic for your knee , and I have had no case of excessive scar tissue (arthrofibrosis). Doing open trochleoplasty it´s a well known risk that on third end up with scar formation and had to undergo new surgery with release of scar formation - read more here. Some will think that the huge cosmetic difference is the most obvious reason - and yes there is a obvious difference. Some choose the arthroscopic method due to less pain and less risk. 

How precise is the surgery by arthroscopic technique?

This recent paper demonstrate that in respect to all measured parameters that characterize the trochlear configuration there was significant improvement comparing pre-operative MRI scans with post-operative MRI scans. Moreover did the patient get stable patella and good subjective results - read more here - open source

Why also MPFL reconstruction?

Why is the groove surgery not enough? And why should you also have reconstructed the MFPL? (mediale patellofemoral ligament = inner ligament for kneecap). That is first of all because the MPFL is always torn when the kneecap dislocate. In most circumstances does it not heal normally and therefore it has to be reconstructed. Moreover it also so, that the trochlear groove, do not provide stability to your kneecap, until the kneecap reach the trochlea. Importantly this first happens after your knee is bend about 20 degrees. This means that the MPFL is needed to provides stability to your kneecap from full straightened knee and until your kneecap reach the new groove at 20 degrees of bending. There is scientific evidence to support this. Read more about MPFL reconstruction here

Arthroscopic trochleoplasty and no MPFL reconstruction. 

If you problem is chronic anterior knee pain as a consequence of a too shallow groove, and your kneecap is stable, likewise you do not need to have the ligament to stabilize the kneecap reconstructed - eventually read more in the page about anterior knee pain.

After surgery 

You are allowed full weight bearing and free range of movement, immediately after your surgery. There will not be applied any brace, but you will need crutches for approximately 3 weeks. You will only stay in hospital for approximately six hours. Some patients have traveled 2000 km back home just after surgery. Patients from Europe typically fly back three days following surgery and patients from US return after a week. The majority start physiotherapy within 3 to 10 days after surgery. Some might think this rehabilitation regime sounds a little scary, however it have proved itself for more than ten years without any problems.

I am Lars Blond pioneer on the arthroscopic trochleoplasty and consider myself as a trochleoplasty specialist. Eventually go to the front page or read my CV or download scientific papers

Trochleoplasty by pinholes = Arthroscopic Trochleoplasty

Patients have been coming from abroad to undergo the surgery. In rara case I travel to where you live.

Until now I have operated patients from 13 different countries:


In case you would like a second opinion regarding your MRI or just your general knee situation, I do Zoom consultations. The cost is 225 euro. E-mail [email protected]


You can eventually go to Facebook. Check out either "Lars Blond + Trochleoplasty" or just "Trochleoplasty". Here you can notice more details and recent updates

Originally the company Arthrex helped me to develop the technique have now also produced at video in 4K quality - see it here

Arthrex is also the company that help other surgeons to learn the technique. Regularly I teach other surgeons in Arthrex Lab in Munich or I am send by Arthrex abroad to help surgeon to do their first cases.


Eventually read what some patients says in the testimonial page - or see this Youtube video called trochleoplasty gathering (Danish language but English text)


What does KneeGuru say about arthroscopic trochleoplasty? - Read here


When are you too old for this? No one know, however the trochlea cartilage have to be fairly okay, without too huge defects. The oldest one I have successfully operated was 57 years.  The youngest was 12 years.

A paper for ordinary people

Read more about arthroscopic trochleoplasty in this paper from 2021 - Research Outreach article - click here

Trochleoplasty surgery cost

The price for an isolated arthroscopic deepening trochleoplasty is approximately 9.000 euro

Will my insurance cover the cost?

In most circumstances you insurance will cover this surgery. A insurance companies like BUPA, Cigna and Storebrand have paid.

Patient from abroad

I have operated many patients from abroad (13 different countries and as far away as Hawaii) Some patients are willing to give advices in respect to travelling, accommodation, physiotherapy and rehabilitation etc. 

Combined surgeries

All the here mentioned surgeries can be combined and sometimes it can be necessary to do both Arthroscopic trochleoplasty, distalization of the tibial tubercle, rotational osteotomy of the femur and tibia and MPFL-reconstruction. 

Frequently asked questions:
  • The surgery typically last 1½- 2½ hours.
  • When can you fly back? This depends on the distance but this is from 1 to 10 days. A seat with the possibility to straighten the leg can be neccesary.
  • Crutches are used for 2-4 weeks - with huge individual differences
  • No brace is needed after this type of surgery and full weight bearing is allowed
  • Some think - should I start with one type of minor surgery and if I do not work, then try another surgery - I my view only one surgery should be necessary if the right one is done from the start.
  • Only one knee is operated (in one out of three both knees are involved)
  • How long is the recovery?
    The knee will improve the first one or two years and will be fairly okay after 3 month.
  • Why is the procedure not more globally widespread? The procedure is technically demanding and you need to have long experience with arthroscopic surgery before you start to learn the technic. The majority of surgeons who do trochleoplasty prefer to do what they feel comfortable with and the think the arthroscopic version is too complicated and too time consuming. The next generation of surgeon will to a higher degree be doing the arthroscopic technique.

More freguently asked questions:
  • When can I return to sport or job - this has very huge individual differences and if you have an sedentary job it is about 4 weeks and lighter sports is after approx. 6 month.
  • Will my insurance pay? Normally they will pay for the surgery and travelling expenses (still cheaper than similar surgery in US)
  • The price for an online consultation incl evaluation of MRI? 225 Euro.
    MRI scans can be posted by mail, by Dropbox or or similar (E-mail: [email protected])
  • The price for combined arthroscopic trochleoplasty and MPFL reconstruction is approx. 11000 euro incl implants (implant cost alone is 2000 euro)
  • For physiotherapy and exercises Physiotherapist Dorte Nielsen ( has a huge experience of training patients troubled by patellar instability, and has seen several patients after arthroscopic trochleoplasty. Dorte Nielsen has uploaded videos on YouTube.
About Aleris Hospital

Aleris Hospital is the largest private hospital in Denmark with 10 operating rooms and has very high safety. A rate of infection close to zero and with high cleanliness and has undergone accreditation after the highest international standards and use the latest technologies. All doctors are experienced doctors. All personnel speaks English.

Rehabilitation protocol after Arthroscopic Trochleoplasty and MPFL reconstruction - by Dorte Nielsen

Rehabilitation trochleoplasty
Example of an "Arthroscopic Deepening Trochleoplasty".

Before (left) and after (right). The blue band dissolves after 6 weeks and is therefore only temporary until the cartilage has healed.

MRI before (left) and after (right)
Trochlea before and and after the groove surgery 

- "It is difficult to balance a tennis ball on a football"

Second look

Two different examples of how it looks in-site the knee 3 months after a groove surgery. If you notice has the cartilage healed very nicely and blue bands/tapes are dissolved.

Second look - 3 years after

Illustration showing the tapes in place after arthroscopic trochleoplasty

Nice small scars after combined arthroscopic trochleoplasty and MFPL reconstruction

The scars after Arthroscopic Trochleoplasty and reconstruction of the medial patellofemoral ligament eight weeks postoperatively

Eight weeks after the surgery and the scars will become much more nice over time. I recommend you to use tape in the first month after surgery, since this will reduce traction in the scars. Hence you can avoid that the scars becomes wide.

Open trochleoplasty

Open trochleoplasty

My last open trochleoplasty

Video arthroscopic trochleoplasty

Kenneth doing well one year after

Why should I also have a groove surgery and not just MPFL reconstruction?

That is a good question and some surgeon argue that it is not necessary. Maybe it is not 100% necessary if you just want stability, but if you also want a knee without anterior knee pain, trochleoplasty have to be done. Also, sometimes I see patients having trochlear dysplasia and who have had an MPFL reconstruction only. Then after some years the kneecap starts to becomes loose again because the MPFL reconstruction get loose by time. Therefore if you visit a surgeons, who do not do trochleoplasty surgery, and you do have this flatt groove. Most importantly try to get a second opinion in case this surgeon tells you that the surgery is rare, dangerous and complicated surgery since this is not correct. 

Case Study - Mikkel

Mikkel was the first patient who was operated upon with an Arthroscopic Trochleoplasty, and this was back in March 2008. Previously he had unsuccessful kneecap-stabilizing surgery and by doctor and physiotherapist he was told that he would never be able to sports again. Most noteworthy Mikkel had been troubled in both his knee since he was 8 years old and had never been able to run. Finally he underwent surgery on both his knees with the groove surgery at 29 years old. Meaning 21 years without running. 

Follow-up on Mikkel

Today is Mikkel doing well in his knees and he is running and playing soccer. He claims that the only annoyance is the sound from the knees, when he climbs stairs. Go to YouTube and listen to his and other stories during the trochleoplasty gathering in 2014. Many thanks to Asker Blønd - my son - who created this video. Click here trochleoplasty gathering.or check this video

Outcome after trochleoplasty

Generally the outcomes after groove surgery is very good, with less than 2 percent new dislocations. Consequently is the quality of life dramatically better. I have followed all my arthroscopic trochleoplasty patients for now more than 10 years and in average there as been improvements in all measured parameters and high satisfaction.  Both the technique and the results of this operation, have been published in peer reviewed journals. Today I have presented "The Arthroscopic Deepening Trochleoplasty" technique in the United States, Japan, Netherlands, UK, Sweden, Norway, Poland, Germany, Austria, Portugal and China. Moreover has the surgery been adopted by other surgeons and is now performed in ten differnet countries world wide.

Tibial Tubercle Transfer =TT?

What about having a TT osteotomy instead of a groove surgery? The fact is that no surgeon know what exactly what is best since the science has not yet given a final answer to that question. However is there many indications that the groove surgery gives better results. In addition we know that trochleoplasty surgery normalize the anatomy. Moreover does we know that patients, who have had TT surgery after a decade are having declining results. The first trochleoplasty patients I operated more than 13 years ago are still doing fine. So based on this and my clinical experience by doing both many tibial tubercle osteotomies an trochleoplasty surgeries, I prefer to do trochleoplasty if you are having severe trochlear dysplasia.

Here is the latest paper on arthroscopic deepening trochleoplasty here or simply go the page where you can find all my scientific papers

LinkedIn 2023

Photo library with some examples of arthrocopic trochleoplasty