Understanding your X-ray: what OA grades mean for your joints

Osteoarthritis on X-ray is most commonly graded using the Kellgren-Lawrence (KL) scale, from 0 to 4. Grade 0 means no visible OA. Grade 1 means doubtful, with possible minor bone spur formation. Grade 2 means mild, with definite bone spurs and possible mild joint space narrowing. Grade 3 means moderate, with multiple bone spurs, definite joint space narrowing, and some sclerosis (hardening of the bone beneath the cartilage). Grade 4 means severe, with large bone spurs, marked joint space narrowing, and significant sclerosis or deformity.

Most doctors tell patients their grade and move quickly to treatment recommendations, often jumping to surgery for Grade 3 or 4. What they rarely explain is the weak relationship between what the X-ray shows and how much pain or disability the patient actually experiences.

This is the most important thing to understand about OA grading: the correlation between X-ray severity and pain is surprisingly weak. Large population studies consistently show that many people with Grade 3 or even Grade 4 OA on X-ray have mild or no symptoms, while some people with Grade 1 or 2 have significant pain.

The reason is that pain in osteoarthritis comes from multiple sources, not just cartilage damage. Muscle weakness, joint stiffness, inflammation of the synovial lining, body weight, physical activity levels, sleep quality, and even psychological factors like fear of movement all contribute to the pain experience. An X-ray only shows bone and joint space. It tells you nothing about these other factors, many of which are modifiable with physiotherapy.

This is why two people with identical X-rays can have completely different levels of pain and function. Treatment should be based on your symptoms and functional limitations, not on the X-ray grade alone.

If a doctor has told you that your knee is "bone-on-bone," you have probably imagined bare bones grinding against each other with every step. The reality is more nuanced. "Bone-on-bone" refers to significant loss of joint space on X-ray, usually KL Grade 4. But X-rays are taken while standing still, and joint space can vary depending on the angle and position of the X-ray.

More importantly, even in advanced OA, the joint still has synovial fluid, ligaments, and a joint capsule providing some cushioning and lubrication. The knee is not simply two dry bones rubbing together. Many patients with so-called "bone-on-bone" X-rays function well with appropriate exercise, weight management, and physiotherapy.

The phrase "bone-on-bone" has unfortunately become a sales pitch for knee replacement surgery. While knee replacement is an excellent operation for the right patient, the decision should be based on your pain levels, functional limitations, and quality of life after trying conservative treatment, not on a dramatic-sounding X-ray description.

Every international guideline on osteoarthritis, from the UK (NICE), US (OARSI, ACR), and Europe (EULAR), agrees on the same first-line treatment: exercise, education, and weight management. This is not a consolation prize before surgery. It is the most effective treatment available for OA symptoms, often outperforming painkillers and injections.

For Grade 1 to 2: Strengthening exercises, particularly for the quadriceps, are the single most effective intervention. Research consistently shows that strengthening the muscles around the joint reduces pain and improves function. A structured physiotherapy program of 6 to 8 weeks typically produces significant improvement. If you are overweight, losing even 5 kg reduces knee load by approximately 20 kg with each step.

For Grade 3 to 4: The same exercise principles apply but may need modification for pain and range of motion. Physiotherapy focuses on maintaining mobility, building strength within available range, and optimizing function. Many patients with Grade 3 and 4 OA manage well for years with regular exercise and periodic physiotherapy, delaying or avoiding surgery altogether.

Treatments with limited evidence include glucosamine supplements, hyaluronic acid injections, and platelet-rich plasma (PRP). These are widely marketed in India but the research on their effectiveness is mixed at best. Exercise remains the gold standard.

Knee replacement is genuinely indicated when all of the following apply: you have significant daily pain that interferes with sleep and basic activities, your quality of life is substantially affected, you have tried at least 3 months of proper physiotherapy and exercise, and you have realistic expectations about the outcome.

Knee replacement is an excellent operation for the right patient. Over 90% of patients report significant pain relief and improved function. But it is a major surgery with a 3 to 6 month recovery period, and the artificial joint has a finite lifespan (typically 15 to 20 years). For patients under 60, the likelihood of needing a revision surgery in their lifetime is significant.

The decision to proceed with surgery should not be driven by the X-ray grade alone, pressure from a surgeon, or fear that the joint will "get worse" without surgery. OA does progress, but the rate varies enormously and is influenced by factors you can control, particularly exercise and body weight.

If you have been told you have OA and are wondering what to do, start with a physiotherapy assessment. A physiotherapist can evaluate your strength, range of motion, functional abilities, and pain levels, and design a targeted exercise program for your specific situation. This works well online because the assessment is movement-based and exercises can be taught and corrected via video.

Nuprana offers structured online physiotherapy programmes for osteoarthritis, with regular sessions and a progressive home exercise plan tailored to your stage. Most patients with OA see meaningful improvement in pain and function within the first 3 to 4 weeks of consistent exercise. The goal is to give you a programme you can maintain independently for long-term joint health.