Understand the knee arthritis stages from 0 to 4, what causes knee arthritis, what a stage can and can't tell you, and what to ask at your consultation.
Knee Arthritis Stages: What Causes It and What Each Stage Means
Most people hear the word "arthritis" long before they hear anything useful about it. This guide covers the knee arthritis stages most clinicians describe, from stage 0 to stage 4, and the knee arthritis causes behind them.
It also covers what a stage can and can't tell you about your own knee, which is the part most articles skip. A doctor says "arthritis," an X-ray report repeats it, and a relative offers a stage number they read somewhere online. None of that tells you much until you know what the number actually measures.
The short version: there is no single cause, the stages describe what the joint looks like rather than how much it hurts, and a stage number on its own never decides your treatment.
What knee arthritis actually is
The type this article covers is osteoarthritis, the wear-related form of arthritis. The protective cartilage that cushions the ends of the bones thins and breaks down, and over time the bones begin to rub against each other. Apollo Hospitals describes it as a "wear and tear" condition that affects the joint as a whole, not just the cartilage.
Symptoms often build up slowly, though Mayo Clinic notes they can also come on relatively quickly. It lists pain during or after movement, tenderness, stiffness that is often worst after waking or after sitting still, a grating sensation, reduced range of motion, and bone spurs that can feel like hard lumps.
Other kinds of arthritis exist, including inflammatory and infectious types. Mayo notes that blood tests or joint fluid analysis are sometimes used to rule those out, which is one reason a proper examination matters before anyone puts a label on your knee.
Knee arthritis causes: why some knees wear out sooner
Here is the honest answer: the cause is not fully understood.
Mayo Clinic says so directly, and instead lists the factors that raise the risk: older age, female sex, obesity, a previous knee injury such as an ACL or meniscus tear, occupations or sports that load the knees heavily, genetics, and abnormal joint alignment.
Most people with knee arthritis have more than one of these. That is why two people of the same age can have very different knees.
What the Indian data adds
A 2021 review in the Journal of Mid-Life Health pooled 18 Indian studies, mostly community and hospital-based surveys. It found knee arthritis prevalence ranging from 27.1 percent to 66.1 percent. The author links that wide range to the lower age limit each study used, which is a useful reminder that these figures depend heavily on who was counted.
The review also reported that women showed higher prevalence in several studies, and that postmenopausal women were affected more often than premenopausal women. High body mass index, high blood pressure, diabetes and osteoporosis were commonly found alongside knee arthritis.
Two cautions. These are associations, not proof that one causes the other. And the author notes there is still little Indian data on how the disease progresses and what disability looks like at each stage.
Knee arthritis stages: the 0 to 4 scale
Clinicians commonly describe knee arthritis on a five-point scale. It is based on what shows up on an X-ray, and the best-known version is the Kellgren and Lawrence grading system. WebMD, in an article medically reviewed in January 2025, describes the stages like this:
Stage 0. A healthy knee. The cartilage is intact and there are no signs of disease.
Stage 1. The cartilage may begin to thin and small bone spurs may start to form, but the joint space is likely not narrowing yet. WebMD notes symptoms may not appear for years at this point.
Stage 2. The knee may ache after a hard workout or a very active day. The joint space may narrow slightly as cartilage decreases, and bone spurs are present.
Stage 3. Pain comes and goes with movement. The joint space is further reduced, the bone ends may become thicker and denser, and fluid may build up and cause swelling.
Stage 4. The most severe stage. There is very little cartilage left, bone spurs are much larger, and daily movement can hurt intensely.
Apollo Hospitals describes the same five stages in broadly similar terms, with a few differences in detail.
What a stage can't tell you
Here is where the honest picture gets more complicated than most online guides admit.
A 2008 review by Schiphof and colleagues looked at epidemiological studies that claimed to use the original Kellgren and Lawrence scale. They found five different written descriptions of the grades, and these differed from the original wording. Grade 2 is often used as the cut-off for diagnosing arthritis, yet the studies did not describe it in the same way. Some even changed their definitions during follow-up.
In practice, that means a stage number is a useful shorthand, not a precise measurement. Two clinicians can reasonably describe the same X-ray slightly differently.
It also matters that a stage describes the joint, not you. WebMD notes that symptoms at stage 1 may not appear for years, so how much your knee hurts and what your X-ray shows do not always move together. Your pain, your walking, and how much the knee limits your day are part of the assessment too.
How knee arthritis is diagnosed
Mayo Clinic describes a straightforward sequence. It starts with a history and physical examination. Plain X-rays are the usual first imaging test, and an MRI may be used when more detail is needed.
The X-ray is the source of the stage. It is also why bringing your previous scans to a consultation is worth the effort.
What treatment looks like across the stages
Treatment is built around the whole picture, not a stage number alone. WebMD groups the options by phase. For the earlier stages (1 to 3), it lists lifestyle changes such as reducing pressure on the knee and losing weight if needed, strengthening exercise, anti-inflammatory and pain medicines, injections into the joint, supports such as a cane or brace, and, in some cases, a procedure to correct alignment.
For stage 4, WebMD describes joint replacement as the option when other therapies have not worked. Apollo Hospitals similarly says surgery is the more likely recommendation at the most severe stage, and that arthritis is irreversible, though treatment can manage the pain and symptoms.
None of this means you must wait for stage 4 or that stage 3 requires surgery. When surgery makes sense depends on how much the knee limits your life, not just what the scan shows.
If surgery does become the right answer, the next question is which operation fits your pattern of damage.
Questions worth asking at your consultation
Because a stage is only part of the picture, it helps to ask more specific questions:
What stage does my X-ray show, and which grading system are you using? Which parts of the knee are affected: the inner side, the outer side, behind the kneecap, or all of them? Which of my risk factors, such as weight, past injury or alignment, can be changed? What should I try first, and how will we know whether it is working? And what would tell you it is time to talk about surgery?
None of these has a universal answer. That is exactly why they are worth asking.
What this looks like at Shaurya Hospital
At Shaurya Hospital, "Dr. Jigar D. Shah" has performed more than 20,000 joint replacement surgeries over 23-plus years. The starting point for any knee, though, is not surgery. It is imaging, an examination, and an honest conversation about what stage the knee is in and what it is actually costing you day to day.
If you have been told you have knee arthritis and are not sure what it means for you, bring your X-rays and the questions above to a consultation.
Book a consultation with Dr. Jigar D. Shah at Shaurya Hospital, Paldi, Ahmedabad, to understand your knee and the options for it. Learn more about Joint Replacement at Shaurya Hospital.
Sources
Mayo Clinic Orthopedics & Sports Medicine. "Knee Arthritis." Causes, risk factors, symptoms and diagnosis. Page last modified March 2021.
WebMD. "Stages of Knee Osteoarthritis." Written by Alexandra McCray, medically reviewed by David Zelman, MD, January 14, 2025.
Apollo Hospitals. "What is Osteoarthritis of the Knee? Stages, Symptoms, Causes, Diagnosis and Treatment." Verified by an Apollo orthopedician team, May 14, 2023.
Schiphof D, Boers M, Bierma-Zeinstra SMA. "Differences in descriptions of Kellgren and Lawrence grades of knee osteoarthritis." Annals of the Rheumatic Diseases, 2008.
Thati S. "Gender differences in osteoarthritis of knee: An Indian perspective." Journal of Mid-Life Health, 2021;12(1):16-20. Also listed on DOAJ.
Shaurya Hospital — existing published content on Dr. Jigar D. Shah's profile and Joint Replacement pages.
