How Osteoarthritis Is Diagnosed

Early, accurate diagnosis of osteoarthritis is necessary so that appropriate treatment options can be considered. Your medical history, physical examination, and imaging studies help diagnose osteoarthritis. During the physical exam, your healthcare provider will check for joint swelling and range of motion. Imaging studies (X-rays) look for joint abnormalities and loss of cartilage. Your practitioner will also make assessments using blood tests to assess your general health and rule out other possible causes for joint problems.

It's important to note that anytime joint pain doesn't go away after a few days, or keeps coming back intermittently over the course of several months, you should consider arthritis—regardless of your age. This is especially true if you have injured that joint at any point in time or have a job that requires repetitive motion, or if you are overweight, as this puts extra strain on the joints.

Intake and Examination

Two of the best diagnostic tools a healthcare provider has are her ears. Taking a thorough medical history and having a discussion about your symptoms, in addition to examining you physically, are very important to arrive at an osteoarthritis diagnosis.

Medical History

Your medical history tells the healthcare provider about the onset of your osteoarthritis symptoms, past treatments or surgeries, your family history of the disease, and other significant details about your condition.

Typically, at the first appointment with your healthcare provider, you will be asked to fill out an extensive questionnaire about your medical history. You will also be asked about the symptoms you are experiencing, including when they commonly occur and what makes the symptoms worse or better.

Your healthcare provider may ask:

• Where does it hurt, and how much?
• How long have you been having these symptoms?
• Is there a pattern?
• Are your joints stiff in the morning?
• Do you feel the pain with certain activities and exercises? If so, which ones?
• Have you changed the way you stand or walk due to the pain?
• Do you have any other symptoms?

Be prepared in advance. Write down or record the information to bring with you so you won't leave out important clues. While you may think some information should already be in your medical record, it is best to recap them. Past surgeries and injuries, including any recent injuries, are important to discuss during your examination.

Physical Exam

During the physical examination, your healthcare provider will assess each of your joints for pain, tenderness, and range of motion. Determining the pattern of affected joints has significance and can often distinguish between rheumatoid arthritis and osteoarthritis (for example, one knee or both knees affected).

She will also do a full general exam to assess your heart, lungs, liver, and kidneys.

The physical examination looks for evidence of:

• Mild to moderate firm swelling around the joint
• Crepitus on movement: this is that crunching feeling, like the sound of bone rubbing on bone (if you have a "noisy knee," that is crepitus)
• Limited range of motion: the joint can't flex as far as it once did
• Pain with movement of the joint, especially toward the end of its range of motion
• Joint tenderness
• Mild inflammation and warmth over the joint

Other physical evidence that your healthcare provider will look for includes:

• Weakness of muscles surrounding the affected joint
• Tenderness of structures surrounding the joint
• Joint instability (with advanced osteoarthritis)
• Joint deformity, such as bony enlargement (with advanced osteoarthritis)
• Bony lumps, especially on the fingers
• Unequal leg lengths
• Altered walking gait

Your initial physical examination establishes a baseline with your healthcare provider. When your practitioner repeats the physical examination on follow-up visits, changes for better or worse will be evident.

Labs and Tests

Routine laboratory tests are sometimes performed to rule out systemic diseases. In addition, healthcare providers sometimes test inflammatory markers, such as C-reactive protein and sedimentation rate, to determine whether the joint discomfort is the product of a systemic inflammatory condition.

When there is joint swelling, synovial fluid analysis can determine whether effusion is inflammatory and rule out specific causes of joint inflammation, such as gout and infection.

This test is performed in a physician's office using aseptic precautions. Your healthcare provider may give you a local anesthetic to help numb the area first. A needle is used to draw synovial fluid from your joint. This synovial fluid is sent for a cell count, bacterial culture, and crystal deposition. Although it sounds unnerving, the process itself is fairly quick, and the procedure only mildly painful.

Imaging

X-rays are typically used to confirm the diagnosis of osteoarthritis. X-rays can reveal assymetric joint space narrowing, osteophytes at the joint margins, joint space narrowing, and subchondral bone sclerosis. Subchondral bone is the layer of bone that is just below the cartilage.

While magnetic resonance imaging (MRI) is a more sensitive imaging method, it is used less often than X-rays due to cost and availability. MRI scans show cartilage, bone, and ligaments.

X-rays alone may give your healthcare provider the information he or she needs to treat your osteoarthritis appropriately, so you may not have an MRI done. In some cases, though, MRIs are done to give a more detailed picture of what is happening in the joint. MRIs can also be used to rule out osteoarthritis or diagnose other types of arthritis.

Diagnostic Criteria

Your healthcare provider will use all of this information to come to a diagnosis. The American College of Rheumatology has established classification criteria, described below, for primary osteoarthritis of the hand, hips, and knees.

Osteoarthritis of the Hand

• Hand pain, aching, or stiffness
• Hard tissue enlargement of two or more of 10 selected joints
• Fewer than three swollen metacarpophalangeal joints
• Hard tissue enlargement of two or more distal interphalangeal (DIP) joints or deformity of two or more of 10 selected joints

The 10 selected joints include:

• Second and third DIP joints of both hands
• Second and third proximal interphalangeal joints of both hands
• First carpometacarpal joints of both hands

Osteoarthritis of the Hip

• Hip pain
• Femoral and/or acetabular osteophytes evident on X-ray or sedimentation rate less than or equal to 20 mm/hour
• Joint space narrowing evident on X-ray

Internal hip rotation of less than or equal to 15 degrees, morning stiffness in the hip lasting less than or equal to one hour, and age of 50 years or older are additional criteria that are useful for diagnosing osteoarthritis of the hip.

Osteoarthritis of the Knee

Knee pain and at least three of the following six criteria:

• 50 years of age or older
• Stiffness lasting less than 30 minutes
• Crepitus
• Bony tenderness
• Bony enlargement
• No warmth to the touch

Laboratory findings useful in assessing knee osteoarthritis include sedimentation rate less than 40 mm/hour, rheumatoid factor less than 1:40, and synovial fluid examination showing clear, viscous fluid with a white blood cell count less than 2,000/mm³.

Differential Diagnoses

Part of this process is differentiating osteoarthritis from other types of arthritis. It is also important to determine whether a patient has primary osteoarthritis or a secondary form of osteoarthritis associated with another disease or condition.

Other issues that have symptoms similar to osteoarthritis include:

• Rheumatoid arthritis
• Gout
• Lupus

Blood tests can often be used to diagnose or rule out these health problems. In the majority of cases, though, diagnosing osteoarthritis is fairly straightforward.

A Word From Verywell

Osteoarthritis is an extremely common cause of joint pain. It is generally a straightforward diagnosis that your healthcare provider will make in their office without further testing. In some cases, your practitioner will utilize laboratory testing and imaging to rule out other underlying inflammatory conditions, such as rheumatoid arthritis.