Treatment of your Anterior Knee Pain (AKP) or Patellofemoral Pain (PFP) usually consists of a mixture of physiotherapy-guided quadriceps and hip exercises, core stability training, and eventually foot orthoses, braces and tape. If you are one those unlucky enough to have chronic anterior knee pain and you have done a lot of rehabilitation without improving your problem, you should read more since surgery might be the right option.
Surgery for anterior knee pain is very complicated and you should look for a surgeon with a special interest in the patellofemoral joint - someone who can examine you competently and correctly interpret your MRI. I normally say that "there is nothing you cannot operate on without risk of making it worse". So be alert and sceptical to what your surgeon suggests to you and eventually get a second opinion from another patellofemoral surgeon - not just a standard orthopaedic surgeon. A solution that is possible is just to live with 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', and this could be a solution for you.
Arthroscopic debridement can occasionally be a solution, if the knee is locking or catching and there is no malalignment - meaning that the kneecap is tracking normally in the groove
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).
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, because doing 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 or release is a name of an operating technique where the outer ligament for the kneecap - which has two layers - is lengthened by the technique you see below, splitting both layers but in different places so that the final result is a lengthening.
Lateral retinaculum lengthening
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.
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 means a high riding patella. The result is that on bending the knee the kneecap reaches the trochlea groove too late, and the result is increased wear of the cartilage on the rear of the kneecap - this causes pain. The problem can be helped out with a distalisation of the tibial tubercle, efficiently pulling the kneecap down into a better position to engage in the groove at the right time. Read more here
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.
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 patient's previous MPFL reconstruction had failed as a result of the unaddressed malrotation. She responded very well to a combined femoral rotational osteotomy and a revision MPFL.
Anterior knee pain also be caused by trochlear dysplasia. In trochlear dysplasia there is too much bone in the groove containing the patella. The groove can be flat or dome shaped and consequently this can increase the pressure in the joint. In these cases unloading the joint pressure by an arthroscopic trochleoplasty can reduce the pressure and consequently the pain. Please check this paper
Trochlear Dysplasia on MRI scan
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.
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.
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
Chronic anterior knee pain
Back in 1998 we did a follow-up on patients having anterior knee pain and found, that about half of the patients continue to have light pain for many years and about one out of 10 continues to have severe chronic pain. You can download a PDF copy here. These results have been confirmed by several others. For the small 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.
With respect to whenever or not the clinical entity called anterior knee pain (AKP) or patellofemoral pain syndrome (PFPS) or chondromalacia patellae leads to arthritis this relationship has now been revealed. It seems that some severely troubled patients end up having arthritis. See the study from Conchie et al.