September 19, 2020

Osteoarthritis: Risk Factors, Symptoms, Diagnosis and Natural Course

Osteoarthritis (OA) is a type of joint disease that results from breakdown of joint cartilage and underlying bone. The most common symptoms are joint pain and stiffness. Usually the symptoms progress slowly over years. Initially they may occur only after exercise but can become constant over time. Other symptoms may include joint swelling, decreased range of motion, and, when the back is affected, weakness or numbness of the arms and legs.

In this article:
Osteoarthritis overview
Risk factors for osteoarthritis
Symptoms of osteoarthritis
Diagnosis of osteoarthritis
Course of osteoarthritis
Where to get more information

Osteoarthritis Overview

Osteoarthritis (OA) is the most common type of arthritis. In OA, the cartilage in the joints (which covers the ends of the bones and allows free movement between them) becomes worn down. In addition to the cartilage thinning out, bone spurs can also form around the edges of the joint (see image below). Some people have joint changes related to OA but do not have pain or other problems. In other people, OA does cause symptoms such as pain, stiffness, reduced joint motion, or changes in the shape of affected joints. Although OA can affect almost any joint, it most commonly affects the hands, knees, hips, feet, and spine.

OA is a chronic condition that has a variable outcome depending on which joint is affected. However, it is not necessarily progressive, and there are several measures that can relieve symptoms and reduce the risk of OA getting worse. Getting an official diagnosis of OA is the first step in ensuring appropriate treatment.

This article reviews the risk factors (conditions which predispose to it), symptoms, diagnosis and the natural course of OA. See the separate article, Treatment of Osteoarthritis (OA), for a review of the management of osteoarthritis.

Normal hip joint
Fig 1 showing a normal hip joint. Credit: CFCF / CC BY-SA

Hip joint with features of osteoarthritis
Fig 2 shows hip joint with osteoarthritis. Note that the cartilage covering the ends of the bone roughens and becomes thin, breaking down and exposing the bone underneath which grows thicker. Bony outgrowths called "osteophytes" can form (not shown in image). The space between the bones also becomes narrower. Credit: CFCF / CC BY-SA

Risk factors for osteoarthritis

A number of factors can increase the risk of developing osteoarthritis (OA); most people with OA have one or more of these factors. They include:

Age — Advancing age is one of the strongest risk factors for OA. The condition rarely occurs in people younger than 40 years of age, but at least 80 percent of people over age 55 have some X-ray evidence of the disorder. However, not all people with arthritis on an X-ray have pain or other joint problems.

Gender — For unknown reasons, women are two to three times more likely than men to develop OA and are more likely to have pain if it does develop.

Obesity — People who are obese are at high risk of developing OA. Losing weight may reduce this risk.

Occupation — OA of the knee has been linked to certain occupations that require frequent squatting and kneeling, including cotton processing, dock work, shipyard work, mining, and carpentry.

OA of the hip has been linked to farm work, construction work, and other activities that require heavy lifting, prolonged standing, or walking several miles each day.

Injury — Substantial joint injury or trauma to a specific joint increases the risk of OA in that joint in the future.

Sports — The risk of OA is increased in people who participate competitively in certain sports that predispose to joint injury. This includes wrestling, boxing, pitching in baseball, cycling, gymnastics, soccer, and football; by contrast, noncompetitive running does not appear to increase the risk of OA.

Symptoms of osteoarthritis

The symptoms of osteoarthritis (OA) usually begin after age 40 and can vary considerably from one person to another. OA most commonly affects the fingers, feet, knees, hip, and spine. OA less commonly affects the elbow, wrist, shoulder, and ankle.

Common symptoms of osteoarthritis are as below:

Pain — The main symptom of OA is joint pain that is worse with activity and relieved by rest. In severe cases, the pain may also occur at rest or at night. The pain usually occurs over or near the affected joint; however, in some cases, the pain may be referred to other areas. For example, a person with OA of the hip may feel pain in the lower thigh or at the knee, and a person with knee OA may feel pain in the upper shin.

Stiffness — Morning stiffness is a common symptom of OA. This stiffness usually resolves well within 30 minutes of rising, but it may recur throughout the day during periods of inactivity. Some people note a change in symptoms related to the weather, particularly more joint pain and stiffness in cold, damp, or low-pressure weather.

Swelling (effusion) — OA may cause a type of joint swelling called an effusion, which results from the accumulation of excess fluid in the joint.

Crackling or grating sensation (crepitus) — Movement of a joint affected by OA may cause a crackling or grating sensation called "crepitus." This sensation likely occurs because of roughening of the normally smooth surfaces inside the joint.

Changes in joint shape — Change in joint shape can be a prominent symptom when small joints in the hands (such as the joints in the fingers or at the base of the thumbs) are affected.

Osteoarthritis of hands showing Heberden and Bouchard nodes
Hard knobs which form in the middle finger joints (known as Bouchard's nodes) and at the farthest joints of the fingers (known as Heberden's nodes) are common features of osteoarthritis in the hands. Credit: Drahreg01 / CC BY-SA
OA often causes outgrowths of bone called bone spurs or "osteophytes". These bony growths can be felt under the skin near the joints and typically grow larger over time. They can contribute to visible swelling, especially in the joints of the hands and feet.

Diagnosis of osteoarthritis

There is no single sign, symptom, or test that can diagnose osteoarthritis (OA). Instead, the diagnosis is based on several factors, including the person's age, history, and symptoms.

For example, knee OA can usually be diagnosed in a person over the age of 50 if the following are present:
  • Pain predominantly when weight-bearing and moving the knee
  • Early morning stiffness lasting for just a short time (less than 30 minutes)
  • A crackling or grating sensation in the knee when going up and down stairs
  • Hard bony enlargement of the knees
OA does not cause inflammation (ie, the joint is not warm to the touch). The symptoms of OA generally vary from day to day but change only slowly over years and may level off or even improve at some point.

Similar symptoms to the above can affect other joints, such as the hands and the hips. As the hip joint is deep inside the body, bony enlargement of this joint is not visible, whereas bony enlargement of finger joints is easy to see. Laboratory tests and imaging studies (such as X-rays) are sometimes done if OA is suspected, particularly if the person's symptoms are atypical, but these tests are not always required to make the diagnosis.

Laboratory tests — Laboratory tests may be used to rule out other diseases if a health care provider suspects that something else may be causing symptoms.

Imaging tests — Imaging is not a routine part of making a diagnosis. It can be helpful when there is lack of clarity around a source of joint pain other than OA. Imaging is required prior to joint replacement surgery to help stage and guide the procedure.

Other types of imaging, such as ultrasound and magnetic resonance imaging (MRI), are not necessary to make a diagnosis but may be used if the diagnosis is uncertain.

Course of osteoarthritis

The course of osteoarthritis (OA) varies greatly between people and depending on which joint is affected. For example, pain and functional restriction due to OA of the hip is most likely to worsen slowly over time, whereas OA affecting the finger joints often causes intermittent pain and stiffness while it is developing, but only minimal symptoms later on. In people whose pain and joint stiffness worsens over time, there is usually intermittent worsening (ie, periods when symptoms get worse followed by periods of stabilization).

Some people with OA are able to function normally despite pain, while others may have difficulty with even simple tasks as a result of pain. Exercise can help decrease pain and improve quality of life. See the separate article, Arthritis and exercise, for more information.

Where to get more information

Your healthcare provider is the best source of information for questions and concerns related to your medical problems, including osteoarthritis.



Reference(s)
1). UpToDate: Patient education: Osteoarthritis symptoms and diagnosis (Beyond the Basics). Available online: https://www.uptodate.com/contents/osteoarthritis-symptoms-and-diagnosis-beyond-the-basics
2). Centers for Disease Control: Osteoarthritis. Available online: https://www.cdc.gov/arthritis/basics/osteoarthritis.htm
3). NHS: Osteoarthritis. Available online: https://www.nhs.uk/conditions/osteoarthritis/
4). National Institute of Arthritis and Musculoskeletal and Skin Diseases. "Osteoarthritis". April 2015. Archived from the original on 18 May 2015. Retrieved 13 May 2015.
5). Arden N, Blanco F, Cooper C, Guermazi A, Hayashi D, Hunter D, Javaid MK, Rannou F, Roemer FW, Reginster JY (2015). Atlas of Osteoarthritis. Springer. p. 21. ISBN 978-1-910315-16-3. Archived from the original on 8 September 2017.

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