When patients come in with a knee problem, they’re often confused when we start examining their ankle. It turns out the writers of the old song “The Knee Bone’s Connected to the Ankle Bone” were wiser than the obvious connection as a knee and an ankle are simply specialized parts of the same machine, and what affects one part of a system affects the other. So can what’s going on in the foot or the ankle predict arthritis in the knee? A new study suggests that this is the case. Let’s look at this in depth.
The hip, knee, ankle and foot are all controlled by spinal nerves in your low back and operated by an interconnected system of tendons and ligaments, which work as finely orchestrated interconnected pulleys.
This amazing biomechanical synchronization that allows us to sit, walk, run, jump, and dance can, therefore, be negatively affected by even slight changes to the biomechanics at any point in the system. This concept explains seemingly strange phenomena, like the fact that ACL surgery not only negatively affects the biomechanics of the operated knee but also affects the other knee as well! This video explains how straightforward and unnoticed biomechanical issues can change things:
What Is Knee Arthritis?
Knee arthritis is a very common but often misunderstood issue in which pain is caused by the nerves in the knee and inflammation and bone spurs can cause stiffness. Knee arthritis is also a damaging interplay between the bone and cartilage of the knee. Instability from lax ligaments due to injury, age, or surgeries, like meniscus or ACL procedures, causes parts of the knee to be exposed to greater forces than other areas. This additional pressure can cause small defects or holes in the cartilage, leaving areas of the bone exposed, and the exposed bone reacts by thickening.
The important point here is that the instability or injury that causes knee arthritis puts additional force on the knee joint and affects the biomechanics of the ankle and other parts of the interconnected system as well.
What Does My Knee Arthritis Have to Do with My Ankle?
The ankle along with the foot is the part of the machine that hits the ground. The ankle is made up of three main bones, and constraining the movement of these bones are strong ligaments. Also the Achilles tendon connects the calf muscle to the heel bone.
Many of us sprain our ankles during our lifetimes and we think nothing of the consequences. However, more often than not, spraining one of those ligaments impacts other parts of the interconnected system and, therefore, puts additional stress on the tendons and ligaments of the knee, just like stretching or injuring any one of the knee tendons or ligaments changes the biomechanics of the ankle.
The New Study that Pulls It All Together
Understanding this relationship and the fact that biomechanical forces often drive the progression of knee arthritis, a new study looked at whether changes in the Achilles tendon were related to the presence and degree of knee arthritis. To do this they put 93 participants, 63 with knee arthritis and 30 without, through a series of tests comparing the thickness of the Achilles tendon. They found a significant correlation between the degree of Achilles tendon thickening and the degree of knee arthritis. In essence, a clear link between the knee and the ankle.
The upshot? While it doesn’t take a rocket scientist to understand that the knee and the ankle are connected, our medical care system in orthopedics has gone the opposite direction toward specializing in specific body parts. This hurts patients and actually educates them that parts like a knee and an ankle are separate machines and not just cogs in the interconnected whole. In this respect, alternative-health practitioners have been much smarter than physicians because they have long understood how the body is one machine. Our Orthopedic 2.0 book explores these relationships, so download the book!