Arthritis 101

Summit arthritis specialist Jerome Perra, M.D., explains some terms you may hear when you’re getting evaluated and treated for arthritis.

young women having pain in injured arm

Arthritis is a very common joint condition, affecting nearly one-quarter of all American adults. If you’re among the millions of people with arthritis, you may hear the following medical terms. We hope this short glossary helps you understand arthritis better.

Arthritis Glossary


Any condition that creates loss of the joint’s normal, smooth surface and usually results in pain and inflammation.

Avascular necrosis

The death of bone cells resulting from localized loss of blood supply to bone.


A condition in which the knees are sticking out away from the body, resulting in increased force on the inside of the knees that can cause arthritis.


The 1/8-inch thick, smooth surface that covers the ends of our bones.


The body’s response to an injured joint, whether that injury is from trauma, overload, or inflammatory disease.

Joint fluid

Normal fluid within any joint that serves lubricate the joint so that it moves smoothly and easily. The body creates this fluid and can replace it quickly. Damaged joints can have too much of this joint fluid, resulting in swelling.


A condition in which the knees are pointed inward, resulting in an increased load on the outside part of the knees that can cause arthritis.


Strong, flexible tissue that connects two bones together, providing stabilization while allowing for motion. Ligaments do not stretch unless damaged.


A joint that isn’t lined up correctly. It results in cartilage degeneration over time.


Also called degenerative arthritis, this is a breakdown of the cartilage surface, resulting from trauma, repetitive joint overload, or abnormal wear patters from poor joint alignment.


Increased contact forces on a joint’s cartilage, which breaks down the cartilage over time. Common causes of overload are repetitive, high-impact activities, obesity, and malalignment.

Rheumatoid arthritis

One of several inflammatory diseases where the body attacks its own joint linings. “Rheumatoid arthritis is different from osteoarthritis, although its symptoms can be similar,” Dr. Perra said.

Synovial lining

The part of the joint that creates the lubricating fluid. It has many nerves, which send messages to the brain about joint position but also send pain messages from arthritis or joint injuries.


Strong tissue that attaches a muscle to a bone. Like ligaments, tendons do not stretch unless damaged.

This is only a partial list, and Dr. Perra encourages people to talk with their doctor about anything they don’t understand. “Patients should always feel free to ask us questions,” he said. “We are here to help.”

When to seek treatment for your arthritis

Arthritis doesn’t have to spell the end of an active life. If you are experiencing worrisome symptoms or persistent pain, the renowned arthritis specialists at Summit Orthopedics can help. We work with you to confirm a diagnosis and develop an appropriate conservative treatment plan. If nonsurgical treatments fail to support your lifestyle goals, fellowship-trained orthopedic surgeons will consult with you and discuss appropriate surgical options. Summit is home to innovative joint replacement options. Our Vadnais Heights Surgery Center is one of a select few nationally to receive The Joint Commission’s Advanced Certification for Total Hip and Total Knee Replacement.

Start your journey to healthier joints. Find your arthritis expert, request an appointment online, or call us at (651) 968–5201 to schedule a consultation.

Summit has convenient locations across the Minneapolis-St. Paul metro area, serving Minnesota and western Wisconsin. We have state-of-the-art centers for comprehensive orthopedic care in Eagan, MNPlymouth, MN, Vadnais Heights, MN, and Woodbury, MN, as well as additional community clinics throughout the metro and southern Minnesota.

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