Knee Pain Can Be A Real Pain In The Butt!
20 Apr 2016 by Graham Nelson
Knee pain is one of the most common conditions people experience, and it can be particularly annoying for the recreational or competitive runner.
It can be felt at the front, sides or behind the knee, with the most common area being the front, around the patella(kneecap). It can affect your walking, going up and down stairs, getting up from a chair, squatting, bending, kneeling and running - particularly up or down hills/inclines.
As physiotherapists, we always look for all possible contributing factors to a client's condition, and this will often involve testing areas that may be somewhat remote from the area of pain.
There have been several studies that have looked at the role of the gluteal muscles in knee pain, both amongst runners and the general population.
A review of all published research examining gluteal muscle function in patello-femoral pain syndrome (PFPS) by Barton et al(2013) found moderate-to-strong evidence indicating gluteus medius (GMed) activity is delayed and of shorter duration during stair negotiation in PFPS sufferers. In addition, limited evidence indicates GMed activity is delayed and of shorter duration during running.
The gluteals consist of 3 muscles - the gluteus maximus (GMax), gluteus medius (Gmed) and gluteus minimus (GMin). GMax is the largest of the gluteal muscles and is the main extensor of the hip, along with assisting in external rotation (outward rotation of hip). GMed sits between GMax and GMin. The function of both Gmed and Gmin is to abduct (move leg outwards/away from the midline) and externally rotate the hip. Through these actions of abduction and external rotation, the gluteal muscles help to stabilise the hip and pelvis during walking and running, preventing increased adduction (movement of the leg inwards) and internal rotation (rotation inwards) of the femur.
Increased adduction and internal rotation of the femur during walking and running also results in an increased valgus angle (angle between the femur and tibia) at the knee, which places increased load through the patello-femoral joint. The gluteal muscles, therefore play an important role in helping to stabilise and unload the knee during running. See photos below:
Stable hip, pelvis and knee Increased adduction and internal rotation of hip
(with increased knee valgus angle)
There is good evidence to suggest that the strength of these muscles is an important factor in knee pain, and a study by Prins and van der Wurff (2009) completed a review of all the literature on hip muscle weakness in women with PFPS. They found strong evidence of a decrease in abduction, external rotation and extension strength compared with healthy controls. This would correlate with weakness in Gluteus Medius and Maximus.
Other studies have shown that runners with PFJP are likely to have increased hip adduction and internal rotation. Dierks et al (2008) found that runners with PFPS displayed weaker hip abductor muscles that were associated with increased hip adduction angles in running. More recently Noerhen et al (2012) also found greater hip adduction and internal rotation in female runners with PFPS.
So, if strong evidence supports the role of gluts in knee pain, it is important to assess if this is the case for a specific person, as it is not the case across the board. A physio assessment can accurately determine the role of glut strength and function to a client's knee condition. Assessment includes a combination of isolated strength/endurance tests of the glut muscles, along with functional screening tests such as single leg stance, single leg squat and hop. In conjunction, a running assessment is extremely important to gain greater insight into the relationship between hip/knee control and glut function in running.
If gluts are found to be weak and this is contributing to a client's PFPS, there is strong evidence to support management with strengthening exercises. Dolak et al. (2011) and Khayambashi et al. 2012 both demonstrated significant improvements in pain and function using hip strengthening exercises for clients with PFPS.
Some examples of good exercises to do if your gluts are contributing to PFPS include:
1.Glut activation in prone: This is also a good test to see if your gluts are activating well. While lying on your stomach, keep your thigh straight and lift your leg off the ground. Feel for activation(tensing of the muscle) in the gluts as you lift your leg. They should switch on immediately as you lift your leg. As an exercise, hold the leg lift for 3-5 seconds and repeat up to 3 x 10.
2. Hip abduction in side-lying: Lying on side, lift top leg up approx. 30cm and hold for 2-3 seconds, then slowly lower back to starting position. Repeat 3 x 10.
3. Hip abduction in standing: You can progress from side-lying to standing, using weight for increased load/resistance. With cable tied around ankle, move leg out to side (abduction), then slowly move back to starting position. Use a resistance where 3 x 10-12 is difficult and causes fatigue, but you can still maintain correct posture and technique. Ensure you keep your back straight when moving the leg back and forth, and minimise leaning to one side too much.
4. External rotation (hip): Starting in side-lying, knees bent up. Keep ankles together and lift top knee. Don't rotate through spine or hips as you lift leg. Hold 2-3 seconds and repeat 3 x 10-12.
Weight-bearing exercises such as squats and single leg squats are also important, but these should only be added under the guidance of your physiotherapist and when these movements do not reproduce any knee pain when done repetitively.
We hope you have found this information useful. If you are suffering with knee pain during running, or in everyday tasks, it may be worth considering an assessment to test your gluts and determine the main contributing factors to your condition. An appropriate management plan can then be implemented, tailored to your specific needs.
We also acknowledge running-physio.com for sharing some of the above information.