Osteoarthritis

(What is that popping noise?)

By Chris Knudsen, PT, DPT

One of the primary problems our bodies face as we age is degenerative arthritis, also known as osteoarthritis. In physical therapy, we deal with osteoarthritis a lot. In fact, it is one of the most common causes of pain that leads people to come see us. There is much to learn about it. Some factors that contribute to this condition are controllable (such as lifestyle) and some are not (genetics and environment).

As we age we have joint pain more frequently. Patients come into The Rehab Center in Lancaster and say, "My Dr. says I have osteoarthritis. Does that mean there is nothing I can do about this pain?"

There are many things that can be done to treat osteoarthritis pain. This is the first of four articles that I will be writing in order to answer that question. To better understand what can be done it would be helpful to know exactly what osteoarthritis really is. In this article we are going to talk about the anatomy and physiology of a joint. In later articles we will address joint disease, treatments for osteoarthritis, physical therapy, and exercise and weight-loss.

Anatomy of a Joint

Any anatomy textbook will tell you that joints are made up of:

• bones

• cartilage

• joint capsule

• synovium

• synovial fluid

• ligaments

• tendons

• bursa

The bones come together in the joint and touch each other; cartilage on the ends of the bones acts as a protective surface for bone to bone contact; the joint capsule is a fibrous sac which surrounds and encloses the entire joint; the synovium is a glistening membrane which lines the inside of the fibrous joint capsule; and inside each moving joint you will find synovial fluid which acts as a lubricant to promote smooth joint movement, and which is secreted by the synovial lining.

Some joints have ligaments within them to connect one bone to another. Other joints have tendons outside the joint capsule to attach muscles to the bones. And some joints have cartilage plates between the bones to act as shock absorbers (such as the menisci in the knee). And finally some joints have bursa (little fluid filled sacs lying between the

tendons and the joint itself to act as a cushion).

The joint has a relatively good blood supply to the outer fibrous capsule, but very little blood flow to the deeper structures inside the joint, like the cartilage and ligaments. We will talk more about this lack of blood flow in our next installment as we take a closer look at joint disease.