Back to Basics With Anatomy 101: What is Arthritis of the Knee?

Mitchell K. Freedman, DO January 21st, 2015

Before we can discuss knee arthritis, we have to know some things about basic joint anatomy and have a general understanding of the knee in particular. In this article, you’ll find the background information you need in order to fully understand the answer to the question: what is arthritis of the knee?

All About Joints

A joint exists anywhere in the body where two different bones of the skeleton come together. With hundreds of bones in the human skeletal system, joints are essential for supporting the structure of our bodies, allowing us to bear our own weight and, of course, for the free movement that we enjoy and often take for granted as a normal part of healthy, human life.

When the ends of two or more bones meet, there are several important parts that allow the joint there to be able to function well. 
Ligaments: These strong, stretchy bands of connective tissue are what literally connect one bone to another and keep the separate pieces of the joint held in place. 
Cartilage: This smooth, slippery substance is the “cushion” that keeps bone from rubbing against bone and allows the joint to move with ease and without pain. When we ask the question, “What is arthritis of the knee,” we must keep in mind the critical role that cartilage plays in the makeup of a healthy joint.
Synovial Membrane: This soft tissue releases a lubricating substances within the joint that helps keep the cartilage smooth in order to reduce friction and facilitate the gliding motion that is characteristic of healthy joints.
All About The Knee Joint
As the largest and strongest of the body’s joints, the knees take on significant responsibility for bearing weight and allowing movement. It is the joint created by the meeting of the femur and the tibia, and it is protected in the front by another bone called the patella (often referred to as the “kneecap”). The knee has four stabilizing ligaments and two wedge-shaped pieces of cartilage called meniscus.
The meniscus work to absorb shock as the knee bears the body’s weight and the cartilage cushions the joint, reducing friction and protecting it from bone-on-bone contact. All of these parts together make up a healthy, whole knee joint. And when the knees are working properly, they allow the body to walk, run, jump, squat, climb, kick and more!
What is Arthritis of the Knee?
Although there are over 100 different forms of the disease, in very simple terms, arthritis is inflammation within a joint. This inflammation can be a result of various root causes, ranging from trauma from injury to diseases such as Lupus. The most common form, though, is osteoarthritis, which is considered to be general, “wear and tear” arthritis that comes with age and use. 
The durability of a person’s cartilage is a matter of genetics, so some people are simply more prone to developing osteoarthritis and those who do, often feel its effects  first in their knees. Symptoms include pain, swelling and stiffness and patients with severe arthritis, usually struggle to complete basic, daily activities such as:
  • Getting in and out of vehicles
  • Climbing stairs or coming down steps
  • Standing or walking for long periods of time
  • Squatting
Diagnosing & Treating Arthritis of the Knee
Sometimes a CT scan or MRI is ordered, but generally physicians are able to diagnose arthritis after a physical exam and x-rays. In order to understand how this is possible, we’ll go back to the original question: what is arthritis of the knee? In the case of osteoarthritis, the inflammation is caused by bone-on-bone interaction in the joint. The reason that the bones are rubbing against one another is the loss of the protective cartilage, which has degenerated over the years.
When x-rays come back showing no space between the tibia and the femur, this indicates to the physician that the patient’s pain is indeed the result of arthritis. Although there is no cure for arthritis, there are many treatment options available to help manage pain and get patients back to a healthy, active lifestyle.
As your physician about which of the following treatment options would work best for your particular case of athritis.
  • Lifestyle modifications
  • Physical therapy
  • Assistive devices
  • Medications
  • Surgery
To make an appointment with a knee specialist at Rothman Orthopaedic Institute, call 1-800-321-999 or fill out an appointment request form online. 

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