BY DAMIEN GLOVER
With hundreds of running and fitness events coming up throughout 2016 and training sessions in full swing, many of you will start experiencing pain at the front of the knee, seemingly underneath or around the kneecap (patella bone). With the advent of many social runs which sees all manner of weekend warrior turn up to show their metal, we are seeing more and more of the extremely common patellofemoral pain syndrome in the last few years.
Runner’s knee, retropatellar pain syndrome and lateral facet compression syndrome are synonymous names for patellofemoral pain syndrome (which is really quite a mouthful, so we shall refer to it as PFPS). It is an overuse disorder due to a mismatch of forces across the kneecap and frequently presents itself either below the kneecap or on either side.
Although it is the most common form of knee pain presenting to general practitioners, physiotherapists, orthopaedic surgeons and sports medicine specialists it can be quite difficult to diagnose based on the wide variety of factors that can cause this mismatch of forces. It also tends to be something that people leave for a long period of time either due to there being minimal pain or due to misinformation. I have just done a google search on patellofemoral pain and have found 5 different videos that give 5 different reasons for what is causing the pain, 1 of which was just plain wrong! It can be very confusing when you receive many different pieces of conflicting advice and doesn’t help in the slightest. You need to find someone to diagnose which forces are at play and how to rectify your individual issue.
To get a better understanding of what’s going wrong, let’s first explore how the patella should function in a perfect adult.
As the knee bends, the kneecap works to transfer load from the muscles in our thigh (quads) to the bone in our lower limb (tibia). In a 2 dimensional representation of the knee we can think of the patella as a pulley as demonstrated below.
However instead of having a nice well oiled wheel to roll over, the kneecap is a nice smooth wedge shaped piece of bone and hyaline cartilage which (should) fit smoothly into the well designed shape of the femoral condyles. This is demonstrated nicely by this xray. If you look down at your bent knee from your comfortable seat in front of your computer, that is the exact image you would see.
The key thing to note here is that it appears the patella surface is all in contact with the femoral surface. This allows for balanced load bearing across the joint surface as the patella runs in the femoral groove every time that you take a step.
This is seems relatively straight forward when we only consider the skeleton. Wedge shaped patella fits into and glides smoothly through the perfect groove that is designed for it right? Happy days! Very rarely do we see someone with PFPS that has skeletal issues. (Though to confuse you more, they definitely do exist. Imagine a wedge shaped patella trying to fit into shallow grooves…ouch).
More commonly we see people who have become misbalanced through the musculature on either side of the patella. It is under constant tension from the muscles and fascia on the inside (vastus medialis obliquus aka VMO) and the outside (vastus lateralis/iliotibial band aka ITB) of the knee in a continual and usually balanced tug of war.
The issue arises as you’d expect. When one team wins the tug of war. Yet you end up being the loser and in pain. The patella gets pulled off centre and all of the nice even load transfer now becomes focussed load bearing on a small piece of bone. Hence we have a malalignment issue as shown below.
An example of load bearing is best demonstrated whilst standing. Stand on both feet and feel the pressure being evenly spread across both feet and evenly between the balls of your feet and your heels. This is even and optimal load bearing. Now stand on one foot. Then on the tip toes of that foot. Then just on the inside of the tiptoes of that foot. The pressure of your entire body is now being exerted on 1/8 of the area that it is supposed to be distributed across. It may not hurt yet, but after a period of time it will.
The pain that you end up experiencing can be from a number of sensitive tissues within the knee itself:
Medial retinaculum under constant tension
Cartilage of the lateral facet of the patella and/or lateral femoral condyle
Subchondral bone of the lateral facet of the patella and/or lateral femoral condyleImpingement of the lateral soft tissues as the patella rolls further over the lateral condyle
However the cause, which is the key to excellent rehabilitation principles, has a more extensive list;
Increase rearfoot pronationIncreased tibia internal rotation
Decrease in flexibility
Decrease in quadriceps strength
Decrease in VMO strength
Strength misbalance through quadriceps
Decreased gluteal function and/or endurance
Increased tension through the ITB and tensor fascia lata
Decreased core function
This list is the most common causes of why we have a malalignment issue and a load bearing problem.
Hence there IS NO SINGLE TREATMENT for PFPS. It is a complex and delicate system of balanced forces with many interacting entities.
TREATMENT FOR PFPS TENDS TO HAVE 2 PHASES
Treatment of the acute knee which include; ice, non steroidal anti inflammatory drugs (NSAID’s) such as ibuprofen and diclofenac (please consult your local pharmacist or GP to ensure it is safe for you to take them), rest from aggravating activities, self release techniques as well as taping and/or bracing.
Treatment that we utilise to rectify the misbalance are; soft tissue techniques, dry needling, use of ECG, self release techniques on the foam roller and spikey ball and most importantly strength training in correct biomechanical alignment.
Spikey ball ($13)
Foam rollers ($)60
Brown Strapping Tape ($15)
Rock Tape ($25)
Damien Glover PhysiotherapistREFERENCES
Thomeé R, Augustsson J, Karlsson J. Patellofemoral pain syndrome: a review of current issues. Sports Med 1999; 28:245.Dixit S, DiFiori JP, Burton M, Mines B. Management of patellofemoral pain syndrome. Am Fam Physician 2007; 75:194.
Pulley – This is Chapter 6 from R. C. Schafer, DC, PhD, FICC’s best-selling book: “Clinical Biomechanics: Musculoskeletal Actions and Reactions” . http://www.chiro.org/ACAPress/Mechanical_Concepts_and_Terms.html