Your Kellgren-Lawrence grade is a description of what your knee X-ray shows — mainly osteophytes (bone spurs) and joint space narrowing — scored from 0 to 4. It is not a measurement of how much pain you have, how far you can walk, or how soon you need surgery.
Two people can carry the same grade and live very different days. That gap between the film and the person is the most useful thing to understand about the number on your report, and it is what the rest of this article is about.
What the grade actually describes
The Kellgren-Lawrence system is radiographic. It was built so that clinicians and researchers could describe the appearance of osteoarthritis on a plain X-ray in a consistent, repeatable way, and it remains the most widely used tool for the radiographic diagnosis of osteoarthritis [1].
Two features do most of the work in the scale: osteophyte formation and joint space narrowing. The scale also carries a built-in assumption that those changes progress in a fixed order — osteophytes first, then narrowing, then deformity of the bone ends — an assumption other authors have criticized [1].
The five grades, 0 through 4
Here is the full scale as described in the orthopaedic literature [1]. Grades 1 and 3 exist and matter; a lot of online explanations skip straight from 0 to 2 to 4.
- Grade 0 — no joint space narrowing and no reactive changes.
- Grade 1 — doubtful joint space narrowing, possible osteophytic lipping.
- Grade 2 — definite osteophytes, possible joint space narrowing.
- Grade 3 — moderate osteophytes, definite joint space narrowing, some sclerosis, possible deformity of the bone ends.
- Grade 4 — large osteophytes, marked joint space narrowing, severe sclerosis, definite deformity of the bone ends.
Grade 4 is the picture most people mean when they say they were told they are “bone on bone.” It is an accurate description of an X-ray. It is not, on its own, a treatment plan.
Why your symptoms may not match your grade
Pain and function come from more than the two features the scale scores. One documented limitation is that joint space narrowing in the absence of osteophyte formation cannot be captured by this system at all — a real problem for patients who have knee pain and radiographic cartilage loss but no osteophytes on their films [1].
Research on how patients actually feel points the same way. In the Osteoarthritis Initiative cohort — adults who either had knee osteoarthritis or were at increased risk of developing it — health-related quality of life was measured against both symptomatic and radiographic definitions of knee osteoarthritis. The symptomatic definition performed better, indicating that the pain experience is an important factor in quality of life related to knee osteoarthritis [3].
So the grade is real information. It is simply not the same information as your experience of the joint.
How consistent is the grade itself?
Less consistent than most patients assume. Reported interobserver reliability for the classification has ranged from 0.51 to 0.89 across studies published since the original description [1]. Educators who set out to build a standardized training tutorial for the scale noted that no standard training for grading existed, which may explain the unsatisfactory reliability of the tool in osteoarthritis research [2].
Practically: the grade on your report is a trained reader’s judgment, not a laboratory value. A second reader might not write the same number.
What we do with your grade
At Regen.MD in St. Louis, the grade is one input among several. We read it next to where your symptoms localize, what activities provoke them, how your examination looks, and what conservative care has already been tried and for how long. That is the substance of our conservative-first evaluation.
Where the clinical picture supports it, we discuss the orthobiologic options we offer — intra-articular and tendon platelet-rich plasma, intraosseous and subchondral platelet-rich plasma, bone marrow aspirate concentrate, and Lipogems. For advanced knee osteoarthritis, platelet-rich plasma is discussed as a bridge therapy before joint replacement. No orthobiologic used here is claimed to rebuild lost cartilage.
When conservative measures have genuinely been exhausted, surgery is part of the plan rather than an admission of failure. Dr. Gurpreet Singh Padda, MD, MBA, MHP is a surgeon, and the practice provides surgery at that point in the pathway. It is never the first thing we reach for.
Find out what is actually driving your knee pain
Regen.MD begins with a paid, physician-led Clinical Evaluation — a review of your history, imaging, and metabolic data, and a written roadmap for what to do next. Evaluation is contingent upon review of your data.
Questions? Call (314) 295-3000 or text (314) 886-5902.
Regen.MD, 4477 Woodson Rd, Suite 103, St. Louis, MO 63134, next to St. Louis Lambert International Airport.
Frequently asked questions
What does Kellgren-Lawrence grade 2 mean?
Grade 2 means definite osteophytes with possible joint space narrowing on the X-ray. It is a description of the film, not a measure of how much your knee hurts or how limited you are, which is why we read it alongside your examination and history when we evaluate knee osteoarthritis and the other conditions we treat.
Does a higher Kellgren-Lawrence grade always mean more pain?
No. The features the scale scores are not the only sources of knee symptoms, and research measuring quality of life against symptomatic versus radiographic definitions of knee osteoarthritis found the symptomatic definition performed better. There is more on how imaging and symptoms diverge in our patient education library.
Does my grade decide whether I need a knee replacement?
It does not decide it on its own. The grade describes radiographic severity; the decision rests on your symptoms, your function, your goals, and what conservative care has already achieved. Where an orthobiologic has a role, we explain it on our orthobiologics page, including the fact that for advanced knee osteoarthritis it is framed as a bridge before joint replacement rather than a substitute for it.
Can two readers give the same knee a different grade?
Yes, and the published reliability data show it. Reported interobserver reliability for the scale has ranged widely across studies, and no standard training for grading existed when educators set out to build one. That is one reason your imaging is reviewed directly by Dr. Gurpreet Singh Padda, MD, MBA, MHP rather than treated as a fixed number on a report.
Sources
- Kohn MD, Sassoon AA, Fernando ND. “Classifications in Brief: Kellgren-Lawrence Classification of Osteoarthritis.” Clinical Orthopaedics and Related Research, 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC4925407/ — referenced for the grade 0 to 4 descriptions, the scale’s status as the most widely used radiographic tool, the criticism of its assumed linear progression, the joint-space-narrowing-without-osteophytes limitation, and the 0.51 to 0.89 interobserver reliability range.
- Hayes B, Kittelson A, Loyd B, Wellsandt E, Flug J, Stevens-Lapsley J. “Assessing Radiographic Knee Osteoarthritis: An Online Training Tutorial for the Kellgren-Lawrence Grading Scale.” MedEdPORTAL, 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC6440422/ — referenced for the absence of standard training in grading and the unsatisfactory reliability of the tool in osteoarthritis research.
- Törmälehto S, Mononen ME, Aarnio E, Arokoski JPA, Korhonen RK, Martikainen J. “Health-related quality of life in relation to symptomatic and radiographic definitions of knee osteoarthritis: data from Osteoarthritis Initiative (OAI) 4-year follow-up study.” Health and Quality of Life Outcomes, 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6069966/ — referenced for the comparison of symptomatic and radiographic definitions of knee osteoarthritis against health utility in the Osteoarthritis Initiative cohort.