Anterior Knee Pain – can it be treated surgically?

The condition of having anterior knee pain is a very common disorder. The majority of patients can successfully be treated without surgery.

First of all is Anterior knee pain a symptom and not a disease. Today we have identified many reasons to have anterior knee pain. Initial treatments of your Anterior Knee Pain (AKP) or Patellofemoral Pain (PFP) consists two thing. First of all is a reduction of level of activity. Next is a mixture of physiotherapy-guided quadriceps and hip exercises, core stability training, and eventually foot orthoses, braces and tape, can be helpful. If you are have chronic anterior knee pain for several years you should read further. You have likely been told to live with your pain by your doctor. Or an orthopedic surgeon have introduced the good model "Functional Envelope" developed by Scott Dye. But in your specific case you think, that is not the best option. If so you should read more since surgery might be scary but it could be an option. 

Surgery for anterior knee pain?

Surgery for anterior knee pain is very complicated and you should look for a surgeon with a special interest in the patellofemoral joint. It has to be a surgeon who you can trust. The surgeon also have to examine you competently. Also the surgeon needs to explain to you exactly the MRI. I normally say that "there is nothing you cannot operate on without risk of making it worse". So be alert and skeptical to what your surgeon might suggest you.

Second opinion

Eventually get a second opinion from another patellofemoral surgeon - not just a standard orthopaedic surgeon. You are also welcome to book at Skype or Whatsapp consultation with me for 150 euro prepaid. I need to see you MRI before the meeting. (contact me on [email protected]). Another solution is to accept the pain and reduce your level of activity to a lower level. The knee surgeon, Scott Dye, has for years spoken for the 'functional envelope'. This could be a solution for you. Eventually you can do some reading in the following special issue incl a paper from my hand.

Possible surgical solutions
  1. Arthroscopic debridement
  2. Arthroscopic plica resection (read here) 
  3. Lateral retinaculum lengthening (or lateral release) - se below
  4. Tibial tubercle medialisation (Fulkerson osteotomy)
  5. Distalisation of the tibial tubercle
  6. Arthroscopic trochleoplasty
  7. ​Lateral patella facetectomy
  8. Femoral derotation osteotomy - se below
  9. Tibial derotation osteotomy
  10. Patellofemoral cartilage restoration
  11. Resection arthroplasty
  12. Patellofemoral arthroplasty
Arthroscopic debridement

Arthroscopic debridement can occasionally be a solution. If the knee is locking or catching and there is no malalignment. This means that the kneecap is tracking normally in the groove.

Chronic anterior knee pain

Back in 1998 we did a follow-up on patients having anterior knee pain.We found, that about half of the patients continue to have light to moderate pain for years. About one out of 10 continues to have severe chronic pain. You can download a PDF copy here. Later have these findings been confirmed by several others. For a group of patients having severe chronic pain, a number of anatomical factors can cause the patella to maltrack or cause the pressure in the patellofemoral joint to increase. These issues can stress the cartilage (chondromalacia patellae) and this can cause inflammation or increased pressure that eventually leads to pain.

In case you would like a second opinion regarding your MRI or just your general knee situation, I do Skype consultations. The cost is 150 euro - email [email protected]

Is there a relationship between AKP and patellofemoral arthritis?

The clinical entity called anterior knee pain (AKP) or patellofemoral pain (PFP) or chondromalacia patellae can leads to arthritis. This relationship has lately been revealed. It seems logic that some severely troubled patients ends up having arthritis. See the study from Conchie et al.

The Scandinavian Congress on Sports Medicine 2018 - take a look at the symposium on anterior knee pain on this youtube video

Lateral retinaculum lengthening

If you are one of those troubled by chronic anterior knee pain it might be that you are having hyperpressure syndrome. This is mostly caused by a tight lateral retinaculum (a kind of ligament that stabilise the patella - see image). 

Tilt of your kneecap

When your retinaculum is tight, this can cause the patella to tilt. Often this tilt can be seen on an MRI scan. A lateral lengthening can in these situations often help to unload the cartilage forces and thereby reduce the pain. You should always undergo an MRI scan to rule out if the tilt is caused by trochlear dysplasia. If you have a lateral release in these cases, there is a risk of making the kneecap unstable, making it subluxate or even dislocate.

The medial and lateral retinacula (singular=retinaculum) help to stabilise the patella

Lateral lengthening technique

Lateral lengthening or release is a name of an operating technique. Here the outer ligament for the kneecap - which has two layers - is lengthened. You see the technique below, first is both layers splitted. Then they are cut in different places, so that the final result is a lengthening.

Anterior knee pain and tibial tubercle osteotomy

Anterior knee pain can in some cases be helped by unloading the patellofemoral joint via the procedure of transposition of the tibial tubercle (TTT), either medially (Elmslie Trillat osteotomy) or anteriorly (Fulkerson osteotomy) - again depending on the MRI findings. If the tibial tubercle is externally rotated, it can be a good idea to have this corrected.

In some patient anterior knee pain is caused by a high riding kneecap (patella alta) and this can also be corrected by doing a distalisation of the tibial tubercle, ,that is moving it downwards.

Fulkerson Osteotomy
Fulkerson Osteotomy candidate

Here you see light patellofemoral osteoarthritis and patella tilt and patellar overhang. The patient responded well on a Fulkerson Osteotomy and lengthening of the laterale retinaculum

Patella Alta

Patella Alta means a high riding patella. The result is that on bending your knee the kneecap reaches the trochlea groove too late, and the result is increased wear of your cartilage on the rear of the kneecap - this causes pain. The problem can be helped out with a distalisation of your tibial tubercle, efficiently pulling the kneecap down into a better position to engage in the groove at the right time. So your pain starts since there is too much stress on your cartilage between the patella and the groove for the kneecap. When your patella sits high, there will be very little overlap between your patella and the trochlear groove, this means that your pressure per square centimeter of cartilage is very high. When your patella is brought back into the trochlear groove, your pressure is actually reduced - and this is in opposition what you as well as many surgeons may think. Read more here

Hoffa Fat Pad Impingement

Hoffa Fat Pad Impingement is a very common explanation for having anterior knee pain. However Hoffas Fat Pad Impingement is not a diagnosis, but something seen on MRI. Hoffa Fat Pad Impingement is cause by maltracking of the patella into the trochlear groove and in most circumstances is based upon Patella Alta or trochlear dysplasia.

Plica Synovialis The parapatellar plica and Infrapatellar plica is closely related to the Hoffa Fat Pad and often the pain is more related to those two plicaes and not the Hoffa. Read a little more about the plicaes here

Fad Pad Impingement - see more here

Corpus Hoffa is seen as orange

References for Hoffa Fat Pad Impingement

1            Matcuk GR, Cen SY, Keyfes V, et al. Superolateral Hoffa fat-pad edema and patellofemoral maltracking: Predictive modeling. Am J Roentgenol 2014;203:207–12.

2            Tsavalas N, Karantanas AH. Suprapatellar fat-pad mass effect: Mri findings and correlation with anterior knee pain. Am J Roentgenol 2013;200:291–6.

3            Widjajahakim R, Roux M, Jarraya M, et al. Relationship of Trochlear Morphology and Patellofemoral Joint Alignment to Superolateral Hoffa Fat Pad Edema on MR Images in Individuals with or at Risk for Osteoarthritis of the Knee: The MOST Study. Radiology 2017;284:806–14.

4            Luyckx T, Didden K, Vandenneucker H, et al. Is there a biomechanical explanation for anterior knee pain in patients with patella alta?: influence of patellar height on patellofemoral contact force, contact area and contact pressure. J Bone Joint Surg Br 2009;91:344–50.

5            AL-Sayyad MJ, Cameron JC. Functional outcome after tibial tubercle transfer for the painful patella alta. Clin Orthop Relat Res 2002:152–62.

6            Jibri Z, Martin D, Mansour R, et al. The association of infrapatellar fat pad oedema with patellar maltracking: A case-control study. Skeletal Radiol 2012;41:925–31.

Anterior Knee Pain and increased femoral anteversion and/or increased tibial external rotation

A malrotated hip, making the knee go inwards (increased anteversion of the femur) can also lead to anterior knee pain due to increased forces on the joint. It needs to be ruled out by clinical examination and in severe cases by a CT scan or special MRI scan. The malrotation can be corrected by a femoral derotational osteotomy. Beneath you see a figure demonstrating a left femur with severe increased internal rotation, causing the patella to dislocate or maltrack causing pain on the outer site of the kneecap. Sometimes the tibia is also involved having too much outer rotation and this also needs correction by a tibia derotational osteotomy - either alone or in combination with a femoral rotational osteotomy.

A malrotated hip, making the knee go inwards (increased anteversion of the femur), can also lead to anterior knee pain due to increased forces on the joint. It needs to be ruled out by clinical examination and in severe cases by a CT scan or special MRI scan. The malrotation can be corrected by a femoral rotational osteotomy. Beneath you see a figure demonstrating a left femur with severe increased internal rotation, causing the patella to dislocate or maltrack causing pain on the outer site of the kneecap.

This image is looking up the femur bone, from the knee up to the pelvis. The left femur (to the right of the image) shows that the shaft of the femur is rotated inwards compared to the other side. The this patient responded well on femoral rotation osteotomy.

Arthroscopic trochleoplasty 

Maybe your Anterior knee pain is caused by severe trochlear dysplasia. If you have trochlear dysplasia you are having too much bone in the groove containing the patella. The groove can be flat or dome shaped and consequently this can increase your pressure in the joint. By unloading the joint pressure by an arthroscopic trochleoplasty this can likely reduce the pressure and consequently your anterior knee pain. Please check this paper

Arthroscopic Trochleoplasty

Trochlear Dysplasia 

Before trochleoplasty

Imidiately after trochleoplasty

Left you see a axial view of a 36 year old women. She had severe anterior knee pain for 20 years. During her patellofemoral arthroplasty surgery there were no cartilage left in the patellofemoral joint. If she just have had a trochleoplasty when she was younger, this may have given her 20 years without pain and likely this soulc also have prevented the development of osteoarthritis

Patellofemoral resurfacing prosthesis

The Hemicap wave prosthesis in an inlay type. It is my experience that by reaching the knee from a lateral approach (outer site of the knee cap) you will get fast recovery and there is full weightbearing from day one. The surgery is performed as one day surgery and often you will be able to drive a car safely after 3-4 weeks. Read more here

Patellofemoral prosthesis Hemicap Wave

Below you see the Hemicap Wave prosthesis for severe patellofemoral osteoathritis. I have very good experience using the inlay prosthesis. The surgery is performed by one day surgery and you are allowed free range of movement and full weight bearing from day one. Read more here

Patellofemoral osteoarthritis

In cases of symptomatic osteoarthritis in the patellofemoral joint, several options exist. Some patient may have symptoms relief by a lateral lengthening, a lateral patella facetectomy, a TTT or a trochleoplasty or cartilage procedures such as microfracture or autologous cartilage transplantation and finally some patients needs to be treated by a patellofemoral prosthesis. Treatments with stemcells is on the exprimental level and right now we are testing adipose stem cell transplantations.

Anterior Knee Pain and Trochlear Dysplasia and osteoarthritis

In some special selected cases I have done a "Resection Arthrosplasty". This is in cases with severe anterior knee pain, trochlear dysplasia and arthritis. Alternative to a prosthesis, a new groove to the patella is made. Apparently this unloads the patella in such a degree that the pain diminishes significantly. Download the Editorial paper from the KSSTA journal by clicking below.  

Resection Arthroplasty