Insall-Salvati Ratio (Patellar Height)
Insall-Salvati ratio (1971) = patellar-tendon length / patellar-bone length; normal 0.8-1.2, < 0.8 patella baja, > 1.2 patella alta.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Patellar-tendon length
- 5.0 mm
- Patellar-bone length
- 4.0 mm
Result: Insall-Salvati ratio 1.25 — patella alta (> 1.2).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- 0.8-1.2
- Normal patellar height.
- < 0.8 / > 1.2
- Patella baja / patella alta (patellar-tendon / patellar-bone length). A radiographic ratio, not a diagnosis.
What you enter
- Patellar-tendon length
- Patellar-bone length
How this is calculated
Insall J, Salvati E. Patella position in the normal knee joint. Radiology. 1971;101(1):101-104. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.