Medical Musings, Health Hypotheses & Therapeutic Thoughts
Finally, we will consider some of the common causes of lateral knee pain. You may remember from the last blog that lateral means 'away from the mid-line of the body', so this is pain on the outside of the knee.
Many of the structures on the outside of the knee are similar to those on the inside, so they do not need much further consideration here (if you haven't yet, I strongly recommend that you read the first few posts about the knee, as they provide some much-needed background and context) These include:
Lateral meniscal injuries e.g. tears
Lateral compartment osteoarthritis
Patellofemoral Pain Syndrome (PFS)
We touched on this in the first common knee conditions blog, talking about anterior or front knee pain where the kneecap does not align properly with the trochlear (meaning 'pulley' in Latin) groove in between the two knobbly bits on the bottom of the thighbone.
Because it is more common that the outer thigh muscles are tighter, as well as the contribution from the iliotibial band (see below), the patella will often track to the lateral side, potentially giving you more pain on the outside of the knee.
Iliotibial Band Syndrome
It extends down the lateral (outside) thigh across the knee, and attaches to the kneecap, tibia (shinbone) and biceps femoris (hamstring, see above) tendon.
Of the muscles whose fascia connects into the ITB, some lift the hip backwards (extension), some out to the side (abduction), and some forwards (flexion). Depending on the portions of the muscle, and the direction of the fibres, they may also rotate the hip inwards or outwards. As you might imagine, this leads to a lot of different forces acting on the ITB.
Repetitive bending and straightening of the knee can cause excessive friction as the ITB rubs over the knobbly bit of bone on the bottom of the thighbone called the lateral femoral condyle. The ITB contacts this bone at around 30 degrees of flexion (bending), so the pain will often be worst in this position. Sufferers of this condition often find themselves walking with a stiff leg to avoid this bending movement.
Hamstring (biceps femoris) injuries
Petsche TS, Selesnick FH. Popliteus tendinitis: tips for diagnosis and management. Phys Sportsmed. 2002;30(8):27–31