Pillar 1: Get Informed
Ok, I get what knee osteoarthritis is and I think I might have it. But what are all these terms? Medial? Patellofemoral? Lateral?
Knowing the location of your knee osteoarthritis is helpful as it helps you to work together with your healthcare team to optimize your care plan. For example, if we are using knee bracing, a different type of brace will be used for those with medial knee OA than that for someone with lateral knee OA. Similarly, we might adjustments your exercise program if you have more arthritis under the kneecap (patellofemoral OA) versus in the medial or lateral ‘tibiofemoral’ knee compartments. It is good to have a sense of where your particular arthritis is so you can communicate more meaningfully with your healthcare team.
Image Credit: SpringLoaded Technologies
Yes, I’m afraid so.
You can have arthritis in one, two, or all three of those compartments.
When one compartment is affected, it is called “unicompartmental” knee osteoarthritis. When 2 or 3 compartments are affected, it is called “multicompartmental osteoarthritis”.
A recent systematic review found that for those who have knee osteoarthritis, approximately 50% have one compartment affected, 33% have two compartments affected, and 17% have all three compartments affected. The most likely compartment to be affected is the inside, or medial compartment
Knee OA Locations
We describe the knee as having 3 compartments. Two of these compartments are formed where the femur meets the tibia bone (the ‘tibiofemoral’ compartments), and one is formed where the patella (kneecap) meets the femur bone (the patellofemoral compartment).
We call the inside tibiofemoral compartment the medial compartment. This is the most common place to have knee osteoarthritis and usually this is just referred to as ‘medial compartment OA’.
The outside tibiofemoral compartment is referred to as the lateral compartment, and if you have knee OA here, we usually refer to it as ‘lateral compartment OA’.
The “patellofemoral” compartment refers to the meeting of the kneecap and the femur. If you have arthritis here, we call it ‘patellofemoral compartment OA’
Can I have Knee OA in more than one compartment?
Image Credit: SpringLoaded Technologies
Will my knee look different depending on where the arthritis is?
On x-ray, we will see differences in the look of your knee. As you or someone else looks at it from the outside however, you may or may not see a difference. Those with more moderate to severe cases of knee OA may have angulation of their knees, and that angulation will depend on where the knee arthritis is wearing down the knee the most.
For example, those with moderate to severe medial compartment knee OA, may see an angling out of their knee and in of their femur. This can give a bow leg, or what is medically called a ‘varus’ knee condition.
Conversely, those with moderate to severe lateral compartment knee OA will tend to have an angling in of the femur bone. This can give a ‘knock-knee’ look, or what is medically called a ‘valgus’ knee condition.