What Is Runner's Knee?
Runner’s knee is one of the most common long-term running injuries. It involves pain behind the kneecap during running caused by a softening, wearing away or cracking of the cartilage under the patella (knee cap). It may also be referred to as Chondromalacia or Patello-femoral Joint Syndrome.
The back of the patella is shaped like a triangle with the point fitting in a grove in the lower part of the bone behind it (the femur). During running, the kneecap is supposed to move up and down within this grove and not side to side. As you run, you land on the outside of your foot and roll inward, causing the lower leg to twist inward. At the same time, three of the four quadriceps muscles which attach to the kneecap, pull it outward and cause the knee cap to rub against edge of the grove on the femur; this is the cause of the pain. The quadriceps muscle on the inside of your knee (called VMO) can counteract this force but needs to be strong enough and function correctly if you are to avoid runners knee. You probably have runner’s knee, if your kneecap hurts when you walk or run, particularly when you walk down stairs. It can hurt a lot when you push the kneecap against the bone behind it. Pain is usually also felt after sitting for a long period of time with the knees bent, this is due to there being increased pressure between the joint surface of the kneecap and the femur.
Signs and Symptoms
The onset of pain in runner’s knee is often gradual and mostly noticed during weight bearing exercises that require knee bending. However if left untreated it can start to become painful with gentle walking and even at rest. The symptoms of runner’s knee can include:
* Pain near the kneecap usually at the medial (inner) portion and below it
* Pain after prolonged sitting with knees bent
* Pain with squatting, hoping, running, kneeling, running hills and using stairs
* Particular difficulty is felt with navigating downhill or downstairs. It is important to note that not all knee pain is patello-femoral pain. There are many other conditions of the knee that runners can commonly suffer from such as Iliotibial band syndrome. This will be covered in a later article.
How Does It Happen?
The exact cause of runner’s knee often varies from athlete to athlete, however as with many overuse injuries biomechanical deficiency can be a major factor. Weakness and dysfunction at another body site can cause extra load on the muscles around the knee leading to injury. Below are some common factors that may increase your risk of developing runner’s knee.
* Tightness in the lateral structures of the knee such as ITB (iliotibial band) and the 3 quad muscles that pull the kneecap outwards
* Reduced strength or incorrect firing of VMO (inside quad muscle)
* Tight calf and hamstrings can increase stress on your kneecap
* Pronating feet (flat feet) or uneven leg length
* Running downhill
* Gluteal weakness and pelvic instability.
* Running with inappropriate shoes, including proper shoes that have worn out
* Training errors, particularly increasing intensity, time or frequency too quickly
* Running on a slanted surfaces (e.g. road camber) or uneven terrain
How Do I Treat Runner’s Knee?
Treatment is to stop the kneecap from rubbing on the edge of the grove of the femur and rather to slide up and down within the grove as it normally should. You can keep the kneecap from rubbing by wearing orthotics, doing exercises to strengthen the muscle that pulls your knee cap inward and by running backwards rather than forward. Surgery is rarely necessary. The most important thing in the early stages is to reduce the stress on the under-surface of the patella and allow healing to begin by:
* Running: Load and volume should be decreased - especially downhill running
* Strengthen the VMO by doing straight leg lifts: Leg lifts should be done 10 times on each side. Start with 5 sets of 10 and work your way up to 10 sets of 10.
* Stretch tight posterior muscles such as calf and hamstring
* Taping patella medially to achieve correct up and down sliding (see pic below)
* Using a patella stabilisation brace to achieve the same result as the taping
* Running shoes that offer extra support should be used. If further control of pronation is needed orthotics should be considered - these can be fitted by your physio.
* Cycling may be pain free and if so can be a good cross-training option while recovering. Up to 30 minutes on the bike, 4 days per week would be a reasonable starting point. You can then build back into running with the assistance of a physiotherapist once able to run/walk pain free.
There are many different variations however the most basic form is to tape the patella medially (inwards) to reduce stress on the knee and to correct the side to side movement of the patella whilst running.
A physiotherapist experienced in treating sports injuries, particularly running injuries may need to show you how to tape your knee cap to decrease the load being placed on it.
Article written by Rob O’Donnell, Physiotherapist and Director of Southern Suburbs Physiotherapy Centre and former Australian Distance running representative. Southern Suburbs Physiotherapy has clinics in 3 locations: 705 Centre Road East Bentleigh, 100 Lower Dandenong Road Parkdale and 99 Bay Street Brighton and there are physio’s with special interests in treating runners at all locations. For more details go to www.sspc.com.au