The 4 stages of knee osteoarthritis are: doubtful, mild, moderate, and severe. We -healthcare professionals- use them to classify the x-ray findings in people with knee joint OA. (1)
Now, a word of caution: Identifying which stage you are in is just one piece of the puzzle. Your x-rays findings shouldn’t be the only deciding factor to design a treatment plan. (2)
Your healthcare professional must combine that information with the findings in your physical exam and medical interview. That’s the only way to have a full picture of your condition to provide the best treatment options.
With that said, this is what we’ll cover. Tap on any of the topics to easily navigate throughout the article:
- The 4 stages of knee OA
- Stage 0 – healthy knee
- Stage 1 – doubtful
- Stage 2 – mild
- Stage 3 – moderate
- Stage 4 – severe
- Treatment options according to each stage
Or keep reading to learn more about:
The stages of osteoarthritis of the knee
Stages can’t describe how severe is your knee pain, or how osteoarthritis affects your life. But they are the best way to know the level of structural damage in this degenerative joint disease.
Now, to determine the stage of OA, your doctor needs an imaging test first – usually an X-ray. With that, she/he will look for the following (1, 3):
- Joint space available. The less joint space between the bones, the more severe OA is.
- Presence of bone spurs. Also called “osteophytes,” bigger or numerous spurs usually mean advanced stages of osteoarthritis.
- Shape of the bones. Any deformities in the bone surfaces can suggest mild to severe OA.
Depending on the findings, your healthcare provider will use one of these stages to classify your knee joint structure:
Stage 0 (Healthy knee)
There are no signs of knee osteoarthritis in this stage. The jointspace is good, there are no bone spurs, and the shape of the bones is normal. (1, 3)
Yet, keep in mind that some researchers think a little lack of joint space still fits into the “healthy” side.
According to them, as long as there’s at least 75% of joint space available, your knee may still be in stage 0. As long as there are no other changes, of course. (1, 3)
Stage 1 (Doubtful)
Here, there’s very minor wear and tear arthritis. Depending on the classification system used, a stage 1 knee osteoarthritis will include the following characteristics (1, 3):
- There’s at least 4 mm of joint space available.
- Minor bone spurs.
- The bone surfaces are a little flattened.
The joint still works properly, at least on a structural level.
Here, the knee pain and inflammation depend on each case.
For some people, their knees will work as usual, without any pain or limitations. But for others, the pain can be extremely incapacitating – to the point of needing surgery. (2)
Side note: That’s one of the many things that make knee osteoarthritis so complex. Rarely do the findings in imaging tests correlate to the severity of the symptoms. (4)
Stage 2 (Mild)
As the disease progresses, the space between the bones may decrease further. Yet, in order to classify for this mild stage, the x-rays should show (1, 3):
- Minor bone spur growth.
- Little joint space available, between 2-4 mm.
- Mild bone deformity, where the bone surfaces look more flat.
As with stage 1, the presence or lack of symptoms highly depends on each case. Yet, bone spurs are a strong indicator of future knee pain. (5)
Pro tip: If your X-ray shows osteophytes but you have little to no symptoms, focus on reducing knee OA risk factors. This will minimize your likelihood of having severe knee pain in the future.
Stage 3 (Moderate)
In this moderate stage, the knee has obvious damage. The x-ray will probably show (1, 3):
- Little to no joint space left.
- More bone spurs.
- Further bone deformity.
- The bone surfaces will likely be thickened due to the damage.
Still, the symptoms of knee OA will differ from person to person. But people in this stage may feel some degree of stiffness due to the lack of joint space. (2)
Stage 4 (Severe)
Here, the cartilage damage is at its worst. In this advanced stage, the x-ray will show (1, 3):
- No joint space left.
- Greater bone spur growth.
- Definite, obvious bone deformity.
Surprisingly, not everyone in this stage will feel pain. But there will likely be limitations in range of movement and some stiffness. (2, 4)
Treatment options according to each knee OA stage
We divided the treatments into two groups – noninvasive and invasive treatments.
Noninvasive treatments ease the symptoms. Some may even slow the progression of the condition.
Whereas invasive treatments need information about your current knee OA stage. This will determine the best approach for your specific case.
Let’s get to it!
Further reading: Ranking of 15 knee OA treatments from best to worst
Noninvasive treatments for knee OA
The thing with knee OA is that symptoms vary widely from person to person. Their intensity can seriously impact your quality of life. Also, they may not correlate with your current OA stage. (2, 3)
That’s why most of the time it’s preferable to manage symptoms and slow the progression of the disease if possible.
The treatments that are best at doing this for knee OA are (6, 7):
Doing regular exercise
Doing exercise of any kind not only keeps your knee joints healthy, it’s also one of the most efficient ways to reduce knee OA pain for good. (6)
This is because strong muscles protect the joints from further degeneration. They also promote blood flow in the area, which boosts the healing process and reduces joint stiffness.
And the best part? It doesn’t really matter what kind of exercise you do. As long as you enjoy it and it doesn’t make your pain worse, you’re good to go.
Try this: 6 exercises to strengthen your knees.
These are a staple in any osteoarthritis treatment because this degenerative condition is irreversible.
So, learning how to reduce pain and joint inflammation at home is essential. This will give you more independence and control over your life. (6, 7)
Common home treatments include:
- Applying heat/cold packs for pain relief.
- Taking nonsteroidal anti-inflammatory drugs.
- Dietary supplements like glucosamine for knee pain.
- Using a TENS unit.
- Wearing a knee brace to ease your daily life.
If you’re not sure which home remedies will suit you best, go to a physical therapist. He/she will give you useful strategies for your specific symptoms.
Or check this out: 11 effective home treatments for knee OA
Invasive treatments for knee osteoarthritis
Your doctor may suggest these treatments if you’re having frequent pain that doesn’t improve with the strategies mentioned above.
For most invasive treatments, it’s vital to know the stage of your knee OA. This will guide your doctor into which remedies will be better for you.
The most common are:
Here, the doctor injects a substance into your knee joint, usually for pain relief. (6, 7)
Corticosteroid injections are popular for knee OA. Here, your physician injects a drug that can reduce pain for up to 3 months. But with one downside – it can accelerate your osteoarthritis. (6)
Another common injection is hyaluronic acid. The doctor injects this substance into the synovial fluid to ease symptoms and promote healing. (8)
This means it may be best for the early stages, as the cartilage isn’t severely damaged.
In theory, surgery should be performed on a knee joint with a severe stage of OA. But this is not true in practice.
Nowadays, knee surgeries for osteoarthritis are done when other treatments can’t ease symptoms anymore. This is regardless of the stage. (2)
For example, a study found that out of 1329 knees waiting for a total knee replacement, more than 18% of them were in stage 1. (2)
Researchers aren’t sure why this happens. It can be due to inefficient treatment strategies, or a poor provider-patient relationship. (2)
In any case, the most common surgeries for knee osteoarthritis include:
- Arthroscopic procedures.
- Cartilage repair procedures.
- Bone realignment surgery – also called “knee osteotomy.”
- Knee replacement surgery – partial or total.
Before we move on, here’s a truth bomb for you:
If you need the surgery that you’re getting, your quality of life will improve exponentially. But if it’s not actually a necessity and you still choose to get it, it might make your symptoms worse. (7)
This might help: A guide to deciding if you need surgery for your knee osteoarthritis.
What are the 4 stages of osteoarthritis in the knee?
The 4 stages of osteoarthritis knee are doubtful, mild, moderate, and severe. The classification system is used to describe the severity of knee OA.
What does stage 3 knee osteoarthritis mean?
How long does it take for knee joint osteoarthritis to progress?
This is extremely variable. It can take a few years to up to 2 decades. It depends on lifestyle, age, genetics, and other individual factors. (9)
Conclusion: The stages of knee OA
There are 4 stages of knee osteoarthritis and each one describes the degree of joint damage. They range from mild to severe.
Classifying your knee osteoarthritis into a specific stage may help design your treatment plan. Yet, the findings in your x-rays can’t be used in isolation to assess your knee osteoarthritis.
Your medical provider must combine them with your medical history, physical examination, and laboratory tests. This will give the full picture so you can receive the best treatment possible.
- Kohn, Mark D et al. “Classifications in Brief: Kellgren-Lawrence Classification of Osteoarthritis.” Clinical orthopaedics and related research vol. 474,8 (2016): 1886-93. DOI: 10.1007/s11999-016-4732-4
- Hernández-Vaquero, Daniel, and José Manuel Fernández-Carreira. “Relationship between radiological grading and clinical status in knee osteoarthritis. A multicentric study.” BMC musculoskeletal disorders vol. 13 194. 9 Oct. 2012, DOI: 10.1186/1471-2474-13-194
- Wright, Rick W, and MARS Group. “Osteoarthritis Classification Scales: Interobserver Reliability and Arthroscopic Correlation.” The Journal of bone and joint surgery. American volume vol. 96,14 (2014): 1145-1151. DOI: 10.2106/JBJS.M.00929
- Culvenor, Adam G et al. “Prevalence of knee osteoarthritis features on magnetic resonance imaging in asymptomatic uninjured adults: a systematic review and meta-analysis.” British journal of sports medicine vol. 53,20 (2019): 1268-1278. DOI: 10.1136/bjsports-2018-099257
- Heidari, Behzad. “Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I.” Caspian journal of internal medicine vol. 2,2 (2011): 205-12.
- American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Evidence-Based Clinical Practice Guideline (3rd Edition). https://www.aaos.org/oak3cpg Published August 31, 2021.
- The Royal Australian College of General Practitioners. Guideline for the management of knee and hip osteoarthritis. 2nd edn. East Melbourne, Vic: RACGP, 2018. Retrieved on December 2021 from: https://www.racgp.org.au/download/Documents/Guidelines/Musculoskeletal/guideline-for-the-management-of-knee-and-hip-oa-2nd-edition.pdf
- Migliore, Alberto, and Simone Procopio. “Effectiveness and utility of hyaluronic acid in osteoarthritis.” Clinical cases in mineral and bone metabolism : the official journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases vol. 12,1 (2015): 31-3. DOI: 10.11138/ccmbm/2015.12.1.031
- Ackerman, Ilana N et al. “Hip and Knee Osteoarthritis Affects Younger People, Too.” The Journal of orthopaedic and sports physical therapy vol. 47,2 (2017): 67-79. DOI: 10.2519/jospt.2017.7286