Knee Osteoarthritis Stage-by-Stage Guide: From Stage 1 to Stage 4

That Grinding in Your Knee Has a Reason

You get out of bed, take the first few steps of the day, and your knee grinds or crunches, refusing to straighten out properly until you've walked it off. Crouch down to bathe a grandchild and the knee stings so much you practically fall backward trying to stand up again. Bend down to trim a toenail and the pain forces you to twist sideways just to reach your foot. Farmers in their sixties describe the same thing after squatting in the field to weed rows of vegetables: they end up leaning on a hoe for a full minute before their knee will unlock enough to stand.

Most of the time what's behind this is degenerative knee osteoarthritis (OA) — a gradual thinning of the cartilage that cushions the joint between bone and bone, along with changes in the bone underneath it. But the single label of arthritis hides a lot of variation. It differs from person to person, and it differs in the same person from month to month. There are stretches where only the first few minutes of the morning feel stiff before things loosen up, and there are stretches where even a flat walk leaves the knee aching all day.

This guide breaks knee osteoarthritis into stages, from early to advanced, and lays out what's actually changing inside the joint at each one, how to get a rough sense of where your own knee sits right now, and how to manage it accordingly. The self-checks here are for reference only — an accurate stage can only be confirmed by an orthopedic exam and an X-ray.

How Degenerative Osteoarthritis Actually Progresses

The knee joint is where the thighbone (femur) meets the shinbone (tibia), and cartilage wraps the ends of both bones so they don't grind directly against each other. With age, and with the accumulated load of repetitive movement and body weight, that cartilage gradually wears thin. The bone underneath can harden, and bony spurs (osteophytes) sometimes form along the joint margins. Mild inflammation in the thin membrane lining the joint (the synovium) is common alongside these changes.

How the Stages Are Defined

The classification used most widely in clinical practice is the X-ray-based Kellgren-Lawrence (K-L) grading system, published by Kellgren and Lawrence in the Annals of the Rheumatic Diseases in 1957. It scores joint space narrowing, osteophyte size, and bone sclerosis to sort knees into five grades, from 0 (normal) to 4 (severe). Nearly seventy years later, it's still the baseline reference orthopedists use when reading a knee X-ray.

One caveat is worth flagging here: X-ray grade and how much pain a person actually feels don't always line up. A systematic review by Bedson and Croft, published in BMC Musculoskeletal Disorders in 2008, found that among people with clear radiographic signs of osteoarthritis, the proportion who actually reported pain ranged from 15% to 76% depending on the study. In other words, some people have advanced X-ray findings and barely notice anything, while others with early-stage X-rays report significant pain. So the staging in this guide isn't purely about X-ray grade — it also weighs the symptoms someone actually lives with day to day. For a case where chronic-stage pain was managed alongside NIR care over eight weeks, see Chronic Knee Osteoarthritis: 58% VAS Reduction with 8 Weeks of NIR Care.

Stage 1 Through Stage 4: What's Happening Inside the Joint

The table below combines K-L grading with the symptoms people typically report at each stage. Individual variation is large, so treat this as a rough map rather than a fixed rule.

Worth stressing: this isn't a straight line. Some people stay at stage 2 for years and then decline suddenly after a bad fall or rapid weight gain. Others get a stage 3 diagnosis and stay largely unchanged for years with consistent management.

Which Stage Am I: A Self-Check

Read through the groups below and pick whichever feels closest to your current state. If you match items across more than one group, it's safer to assume the more advanced one. Whatever the result, an orthopedic exam is the only way to confirm an actual diagnosis.

Closer to stage 1-2

• Only the first few steps of the morning feel stiff, and it resolves quickly
• Fine most of the time, achy only after hiking, long walks, or stair-climbing workouts
• The knee makes noise but there's barely any pain with it
• Kneeling or sitting cross-legged is still manageable

Closer to stage 3

• Stinging pain even while walking on flat ground
• You've started avoiding kneeling or sitting cross-legged because of the pain it causes
• Morning stiffness lasts more than 30 minutes
• You need to hold the handrail going down stairs
• Cloudy or cold weather makes the knee noticeably worse

Possible stage 4

• Aching even while sitting or lying still
• The leg visibly bows outward when you look in a mirror
• You've woken up from knee pain more than once
• Getting through the day without pain medication is difficult

Signs That Mean See a Doctor Now

Whatever stage you fall into, the signs below mean you should stop trying to manage things at home and get seen right away. Stage-based self-care applies when none of these emergency signs are present — it is not a substitute for recognizing them.

• Waking repeatedly at night from pain that doesn't ease with rest: this can point to something more than routine degenerative change, including inflammatory arthritis or another underlying condition.
• Noticeable weight loss with no diet change behind it: this needs to be worked up separately from the joint itself to rule out a systemic illness.
• Swelling and warmth in the knee together with chills or fever: this raises concern for a septic joint infection, which is a medical emergency.
• Sudden leg weakness or loss of bowel/bladder control alongside the knee pain: this suggests the problem may originate from the spine or nerves rather than the knee itself, and needs a neurological workup.
• Pain severe enough after a fall or impact that you cannot bear weight at all: this raises concern for a fracture or ligament tear.
• The knee suddenly won't fully straighten or locks at a certain angle: this can indicate a meniscus tear or loose body caught in the joint.

For a more detailed breakdown of warning signs by symptom, see When to See a Doctor for Knee Pain: Warning Signs by Symptom.

A Different Approach for Each Stage

The 2019 update to the Osteoarthritis Research Society International (OARSI) guidelines, led by Bannuru and colleagues, recommends weight management and exercise therapy as core first-line care across every stage, with pain medication or joint injections used as supportive add-ons when pain is significant, and joint replacement surgery reserved for advanced stages that haven't responded adequately to conservative care.

Stage 1: Prevention Is the Priority

Pain is minimal or absent at this stage, but it's precisely the window where building strength does the most to slow future progression. Starting quadriceps strengthening three to four times a week is a reasonable baseline, and any increase in hiking or stair-climbing activity should be gradual — roughly 10% more per week rather than a sudden jump.

Stage 2-3: Balancing Pain Control With Strength Maintenance

This is where good days and bad days start to diverge noticeably. On flare days, cut back on deep knee-bending movements like squatting or sitting cross-legged; on better days, keep the strength work going. This is also the point where more people start using aids like orthotic insoles or a cane, alongside conditioning approaches such as NIR care around workouts.

Stage 4: Time to Discuss Next Steps With a Specialist

If conservative care — exercise, weight management, pain medication, injections — has been tried adequately and daily life is still significantly limited, joint replacement surgery and other next-step treatments should be discussed with an orthopedic specialist. Self-care at this stage, regardless of whether surgery happens, is aimed at preserving as much strength as possible to support a faster recovery afterward.

How Body Weight Affects the Knee

A study by Messier and colleagues, published in Arthritis & Rheumatism in 2005, analyzed the relationship between weight and knee load in 142 overweight and obese adults. It found that for every pound (about 0.45 kg) of weight lost, the load placed on the knee per step dropped by roughly four pounds (about 1.8 kg). A simple extrapolation would put a 10-pound (4.5 kg) loss at roughly 40 pounds (18 kg) less load per step. That said, the study population skewed toward higher body-weight ranges, so it's not established whether the same ratio holds for people closer to a normal weight.

A Stage-by-Stage Home Exercise Plan: 6-Week Progression

A 2015 meta-analysis by Fransen and colleagues, published in the Cochrane Database of Systematic Reviews, pooled 54 trials covering 3,913 people with knee osteoarthritis and concluded that exercise therapy produces a moderate reduction in pain (standardized mean difference of about 0.49) along with a meaningful improvement in physical function. Most of the trials included, though, followed people for only three to six months, and the review also noted that benefits tend to fade once exercise stops — so consistency is really what determines the outcome.

Stage 1 Exercise: Straight-Leg Raise

• Starting position: Lie on your back on a bed or the floor, bend one knee, and keep the working leg straight.
• Movement: Tighten the front of the straight thigh and lift the heel 20-30 cm off the surface.
• Breathing: Exhale as you lift, breathe normally during the 5-second hold, inhale as you lower.
• Reps/sets: 10 reps x 3 sets, both legs
• Frequency: 5-6 times a week
• Common mistake: Rocking the lower back to help lift the leg higher. Keep the back flat against the floor and let the thigh muscle alone do the lifting.

Stage 2 Exercise: Sit-to-Stand From a Chair

• Starting position: Stand in front of a sturdy armless chair, lightly resting your fingertips on a table or the chair back for balance.
• Movement: Push the hips back and lower slowly, keeping the knee from tracking past the toes, then stand back up.
• Breathing: Inhale while sitting down, exhale while standing up.
• Reps/sets: 10 reps x 3 sets
• Frequency: 4-5 times a week
• Common mistake: Using momentum to lurch forward and pop up out of the chair. That spikes load on the knee in an instant — stand up at a steady, controlled pace instead.

Stage 3+ Exercise: Wall-Supported Shallow Squat

• Starting position: Stand with your back against a wall, feet about 30 cm out in front of you.
• Movement: Slide down the wall, bending the knees only to about 0-30 degrees, then push back up. At stage 3 and beyond, never go deeper than this while pain is present.
• Breathing: Inhale on the way down, exhale on the way up.
• Reps/sets: 8-10 reps x 2-3 sets
• Frequency: 3-4 times a week, skip on days with significant pain
• Common mistake: Pushing through pain to go deeper. If pain crosses 3 out of 10, shorten the range right there.

Using NIR Care to Support Post-Workout Conditioning

Alongside a staged exercise plan, near-infrared (NIR) care is sometimes used to help with muscle and joint conditioning before or after training. It's worth being precise about what this is: it's not a medical procedure that diagnoses or treats osteoarthritis, it's a wellness aid that can help someone stick with an exercise routine consistently.

The Basic Idea

• Supporting cellular metabolism: Near-infrared wavelengths reach tissue beneath the skin and are thought to interact with cellular energy metabolism, an area studied under the term photobiomodulation.
• Local blood flow changes: A temporary increase in local blood flow, along with a sensation of warmth at the treated area, has been reported.
• Post-exercise relaxation: It's commonly used to support a sense of relief in the quadriceps and the muscles around the knee after sit-to-stand work or shallow squats.

How to Work It Into a Routine

If you're using a near-infrared healthcare device such as the CIRIUS LED Pro or Compact, keep the following in mind.

• Hold the device 5-10 cm from the skin, aimed at the front of the knee and the quadriceps
• Apply for 10-15 minutes right after exercise
• It fits best as part of a recovery-and-conditioning routine rather than during an acute flare-up, where consistency matters more than intensity
• It does not replace existing treatment or a clinician's instructions — if pain persists, or if any of the warning signs above appear, see a doctor

Kneeling, Stairs, the Bathroom: Cutting Daily Strain on the Knee

Daily routines for many older adults are full of moments that force the knee into a deep bend. A few adjustments to these habits can meaningfully reduce the load the joint absorbs each day.

Squat Toilets and Floor-Level Living

• Switch to a raised, seated toilet where possible; if a squat toilet is unavoidable, install a grab bar so the arms can take some of the load off the knees.
• For occasions that require kneeling on the floor for an extended time, use a thick cushion or a knee pad in advance to reduce pressure at the contact point.
• Eating at a table and chair rather than sitting on the floor reduces how much the knee has to bend during meals.

Gardening and Housework

• For weeding or garden work that involves squatting, use a low stool or a gardening knee pad to reduce how deeply the knee has to bend.
• Don't stay crouched in one position for a long stretch — stand up, straighten the legs, and walk a bit every 20-30 minutes.
• When picking up a grandchild, bend at the knees rather than the back, and keep the child close to your body as you lift.

Stairs and Footwear

• Always use the handrail on stairs, and decide ahead of time which leg leads on the way up or down so you keep a consistent rhythm.
• Avoid shoes with thin, stiff soles or high heels, which reduce shock absorption; choose footwear with adequate cushioning instead.

For a more detailed five-minute daily routine, see A Daily Knee Care Routine: Why Five Minutes in Three Steps Is Enough.

Common Misconceptions About Osteoarthritis

"Osteoarthritis is just what happens when you get old — nothing to be done"

Age is a real risk factor, but strength, body weight, and activity habits shape the rate of progression just as much. Two people in their seventies can have very different outcomes: the one who has kept up strength training typically shows far less pain and functional decline.

"If your knee hurts, you should rest completely until it heals"

Unless there's an acute injury or significant swelling, staying within a pain-tolerable range of strength exercise tends to work better long-term than complete rest. The meta-analysis cited above found exercise therapy improved both pain and function.

"If the knee cracks or pops, surgery is coming soon"

Joint noise without pain is generally not clinically meaningful on its own. The decision to consider surgery is based on pain severity, functional limitation, and response to conservative treatment — not on noise.

"Once you're diagnosed with osteoarthritis, surgery is inevitable"

In practice, a large share of people at stages 1 through 3 go many years with little change using weight management, exercise, and, when needed, pain medication or injections. Surgery is one option considered when conservative care doesn't provide enough relief at advanced stages. For movements and exercises to avoid during a flare-up, see 6 Exercises and Habits to Avoid When Your Knee Hurts.