Glossary
KL grade (Kellgren–Lawrence)
Quick answer
The Kellgren–Lawrence (KL) grade rates knee osteoarthritis on X-ray from 0 (none) to 4 (severe), based on bone spurs, joint space narrowing and bone changes. It helps describe how advanced arthritis is, but treatment depends on symptoms as much as the grade, explains Doha knee surgeon Dr. Pablo Gelber at Aman Hospital.
The five grades
- Grade 0: no signs of arthritis.
- Grade 1: doubtful narrowing of the joint space and possible tiny bone spurs.
- Grade 2: definite bone spurs and possible narrowing.
- Grade 3: several bone spurs, definite narrowing, some hardening of the bone and possible deformity.
- Grade 4: large bone spurs, marked narrowing, severe hardening and clear deformity of the bone ends.
What it means for patients
The grade comes from a standing X-ray and is a snapshot of bone changes. It does not measure pain. Some people with grade 3 changes walk comfortably, while others with grade 2 struggle. That is why the surgeon treats you, not the X-ray.
As a rough guide, grades 1 to 2 are usually managed with exercise, weight management, activity changes and sometimes injections. Grades 3 to 4 with persistent pain that limits daily life may lead to a discussion about osteotomy or partial or total knee replacement, depending on which part of the knee is worn and your age and goals.
Frequently asked questions
My report says KL grade 2. Is that bad?
It means mild to moderate arthritis. Many people with grade 2 do well with strengthening, weight management and activity changes for years.
Does grade 4 mean I need a knee replacement?
Not automatically. Replacement is considered when severe changes cause pain and limitation that do not respond to other treatment. The decision is personal.
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