Runner’s Knee (a.k.a. Patellofemoral Pain Syndrome)
With the completion of the City2Surf yesterday and over 80,000 runners completing the event, there will be many a person experiencing pain at the front of the knee, seemingly underneath or around the kneecap (patella bone) today. With social running on the rise (and what more natural way to get those endorphins flowing than the activity we evolved to do?), we are seeing more and more of the extremely common patellofemoral pain syndrome.
Runner’s knee, retropatellar pain syndrome and lateral facet compression syndrome are synonymous names for patellofemoral pain syndrome. What a mouthful. Let’s call it runner’s knee. It is an overuse injury due to a mismatch of forces across the kneecap and frequently presents itself either below the kneecap or on either side of the knee.
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 imbalance. Also, as the pain generally starts 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 not just wrong, but potentially dangerous! It can be very confusing when you receive many different pieces of conflicting advice and doesn’t help in the slightest (and yes, I do see the irony that I am now also giving advice). 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 in the picture 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 (in theory) fits 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, use your xray google and this is the exact image you would see of your left knee.
The key thing to note here is that it appears the patella surface is not in perfect contact with the femoral condyles. In this xray we see that the lateral condyle (on the left) has a slightly smaller space than the medial condyle on the inside. In a perfect example this would be uniform. This allows for balanced, uniform 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? This repeats forever and ever and we never have any issues. 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).
SO WHAT GOES WRONG?
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 suffering knee 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. Hop up out of your chair… don’t worry, I’ll wait. 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, you bet your bottom dollar, 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 condyle
• Impingement 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 pronation
• Increased 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 Runner’s Knee. It is a complex and delicate system of balanced forces with many interacting entities.
TREATMENT FOR RUNNER’S KNEE 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. One of the most useful pieces of information is a running biomechanics analysis as this provides invaluable information on your running style. Every excellent sports physio will have the ability to do this. For example at The Beaches Sports Physio we utilise slow motion capture and angular analysis software on our AirRunner to determine what imbalances may be at play.
So to sign off, if you are experiencing any knee pain during or after running, or even during preparation for your local event such as our Northern Beaches own Pub2Pub Charity Fun Run and Festival (from Dee Why, Brookvale or Mona Vale all culminating in Newport) then please see you local sports specialist rehabilitation provider and get it sorted before it becomes a chronic issue.
Titled Musculoskeletal Physio and Sports Rehabilitation Specialist
The Beaches Sports Physio
1. Thomeé R, Augustsson J, Karlsson J. Patellofemoral pain syndrome: a review of current issues. Sports Med 1999; 28:245.
2. 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