Lars Blønd

Osteoarthritis of the kneecap

Osteoarthritis of the Patella (Patellofemoral Osteoarthritis) – Symptoms, Causes, and Treatment

Osteoarthritis of the patella—also known as patellofemoral osteoarthritis—is a common cause of pain in the front of the knee. The condition is typically caused by cartilage degeneration combined with altered patellar tracking, patella alta, or trochlear dysplasia. This article reviews the symptoms, causes, diagnosis, and modern treatment options.

What is osteoarthritis of the patella?

  • Brief Explanation of the Patellofemoral Joint
  • Typical symptoms (pain when climbing stairs, bending the knees, standing up or sitting down)

Why does osteoarthritis develop in the kneecap?

Symptoms

  • Pain in front of the knee
  • Pain When Climbing Stairs
  • Pain When Squatting
  • Cracking/crepitus
  • Swelling

Diagnostics

  • Clinical Examination
  • X-ray (possibly Sunrise View)
  • MRI scan
  • Assessment of Alignment (Quadriceps Malalignment, TT-TG, Patellar Tilt, Trochlear Shape)

Treatment

  • Quadriceps Training and Strengthening
  • Weight loss (if applicable)
  • Pain reliever/anti-inflammatory
  • Patella-Stabilizing Exercises
  • Insoles / Taping
  • Injections (e.g., PRP, Arthrosamid, and hyaluronic acid)
  • Surgery (Osteotomy and Patellofemoral Prosthesis)
Osteoarthritis of the kneecap

It doesn’t always cause problems and many people live perfectly well without having problems with osteoarthritis of the kneecap joint. If you’re have knee pain as a result of osteoarthritis of the patella joint, there’s a good chance you can recover with GLA:D training. Read more about osteoarthritis of the knee joint here. If you have tried everything to avoid surgery and you still experience significant problems with pain and it significantly affects your activity level or sleep, you should consider undergoing surgery. 

Symptoms of osteoarthritis of the kneecap

Typically, there is pain at the front of the knee. The discomfort is triggered when climbing stairs and when the knee is bent for a long period of time. It’s not uncommon for it to creak, crackle and click. However, there may be other reasons why the knee makes noises and we do not treat noises. Sometimes it feels like the knee has to start moving and once it does, it’s actually okay. If the knee has been in motion for a long time, it becomes sore and may swell. Nocturnal pain is not uncommon.

Kneecap osteoarthritis surgery

Surgery for osteoarthritis of the kneecap can be many things. It doesn’t necessarily have to be a knee replacement (new knee). Below are a number of different surgeries that can help with osteoarthritis of the patellofemoral joint.

Kneecap surgery for osteoarthritis of the kneecap

An arthroscopy cannot restore the worn cartilage. If your discomfort is largely locked because the cartilage is irregular, arthroscopic surgery may be considered. If the MRI scan shows that your kneecap is properly aligned in the groove and there are only slight cartilage changes, then knee surgery may be successful. Here the cartilage can be smoothed and irritated synovial membrane removed. Unfortunately, this procedure is not always effective, but there is a very small risk with an arthroscopic surgery. If it’s successful and it doesn’t work, one of the following surgeries may be considered.

Lateral facetectomy

Some people can benefit for many years from having just the outer part of the kneecap removed, known as a lateral facetectomy. This is when the osteoarthritis in the joint is only in the outer part of the joint. The outer part of the kneecap can then be removed, either through arthroscopic surgery or a smaller open operation. In the image to the far right, you can see that the outer part of the kneecap has been removed (it can be seen to the far left in the right image)

Patellofemoral prosthesis

If there is significant osteoarthritis (wear and tear) in the joint between the kneecap and its trochlear groove, a partial prosthesis may be a good solution. The image below shows different images of the Hemicap Wave prosthesis. It is a highly customizable type of prosthesis and is a so-called re-surfacing prosthesis, which has a number of advantages. Why not just replace the entire knee? Because the results for this type of surgery are better than replacing the entire knee. In addition, research has shown that the development of osteoarthritis in the rest of the knee can be reduced with the Hemicap Wave prosthesis. If the kneecap has a tendency to dislocate, the surgery can be combined with a reconstruction of the medial patellofemoral ligament using an artificial ligament (MPFL reconstruction)

Aftercare of Patellofemoral prosthesis

After a kneecap replacement surgery, you can support your knee immediately and go home the same day as your surgery. Physiotherapy starts approximately 2 weeks after surgery. In some cases, driving can be safely resumed after 3-4 weeks, but it often takes 3 months before the knee is better than before surgery and sometimes even longer. In some cases, it may be necessary to perform a subsequent arthroscopy due to scar tissue forming, which becomes trapped and causes pain. This can be removed with a surgical procedure.  

Model showing before surgery with patellofemoral prosthesis

Model showing after patellofemoral prosthesis surgery – Hemicap Wave

Why do you get isolated osteoarthritis between the kneecap and its trochlear groove?

In about 80% of cases, the cause is to be found in something called trochlear dysplasia – this means a flat groove to the kneecap (the groove is not deep enough) and about 15% of all people have such a condition, which can be more or less pronounced. In 20% of cases, the cause must be found in other conditions, such as a high kneecap or damaged cartilage after a fall on the knee. When a Hemicap Wave prosthesis is inserted, the shallow groove is automatically transformed into a deeper groove that has a shape similar to a normal knee.

How long does a Patellofemoral prosthesis last?

This is a difficult question to answer accurately. The type of patellofemoral prosthesis is called onlay prosthesis, 75% of the inserted PF prosthesis will not have been replaced within 15 years. In other words, most will last for more than 20 years. The Hemicap Wave prosthesis that I use is a relatively new type of prosthesis based on a more modern concept and only started in 2006.  

I perform a relatively large number of these types of surgeries and they are typically patients from all over Denmark. Many patients report that they have been informed by their own orthopedic surgeon that this type of prosthesis is not good and is experimental. Of course, that’s not the case and I’ve had almost nothing but good experiences. I insert 30 of these types of partial prosthesis annually. About 20% don’t turn out well, and then I have to do an arthroscopic surgical procedure where I remove small amounts of irritated tissue and then they typically turn out well. According to the manufacturer, one of the prostheses I have inserted over the years has been replaced with a total knee replacement.

Patellofemoral prosthesis

Patellofemoral prosthesis

Hemicap Wave patellofemoral prosthesis

On the left is a picture of a 36-year-old woman who has had anterior knee pain for 20 years. She clearly has severe trochlear dysplasia. At the time of her patellofemoral prosthesis insertion, the cartilage in the joint between the kneecap and its groove was completely worn away. If only she had undergone a trockleoplasty surgery 20 years earlier  She could most likely have had 20 years without pain and probably could have prevented the osteoarthritis. This would have made a knee replacement unnecessary at the age of 36!

Hemicap Wave patient information (danish)

What the Hemicap Wave Patellofemoral prosthesis looks like on an X-ray

Fulkerson Tibial Osteotomy surgery

This special surgery moves the attachment of the patellar tendon to the tibia further inward and slightly forward. In some special cases, it can reduce your anterior knee pain (Fulkerson surgery). This is an operation that is planned based on an MRI scan. Here you can see if the kneecap attachment is rotated incorrectly on the tibia. The surgery is often combined with lateral retinaculum lengthening and/or lateral patella facetectomy, where the outer part of the kneecap is removed. After such an operation, there may be a few weeks where you can’t fully support your leg. Fulkerson surgeryis a common operation for patients with incipient osteoarthritis in the joint with the kneecap and the guiding groove. The surgery can postpone the need for a Hemicap prosthesis in the knee.  

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