Tonnis Classification (Hip Osteoarthritis)
Tonnis classification (Tonnis 1987) of hip osteoarthritis on an AP pelvis radiograph (grades 0-3), the hip counterpart to the general Kellgren-Lawrence grade.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Tonnis grade
- Grade 2 - small cysts, moderate narrowing, moderate loss of sphericity
Result: Tonnis grade 2: small subchondral cysts, moderate joint-space narrowing, and moderate loss of femoral-head sphericity; radiographic osteoarthritis.
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What the result means
- Grade 0 / 1
- 0: no OA. 1: slight sclerosis, slight joint-space narrowing, small osteophytes; no or slight loss of head sphericity.
- Grade 2
- Small cysts, moderate narrowing, moderate loss of head sphericity. Grade 2+ defines radiographic hip OA.
- Grade 3
- Large cysts, severe narrowing or obliteration, head deformity, or avascular necrosis; end-stage.
What you enter
- Tonnis grade
How this is calculated
Tonnis D. Congenital Dysplasia and Dislocation of the Hip in Children and Adults. Berlin: Springer-Verlag; 1987. Grades cross-verified against Kovalenko B, et al. Clin Orthop Relat Res. 2018;476(8):1680-1684. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.