Blackburne-Peel Index (Patellar Height)
Blackburne-Peel index of patellar height on a lateral knee radiograph at about 30 degrees of flexion.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Distance A
- 24 mm
- Length B
- 30 mm
Result: Blackburne-Peel index 0.80 (A 24 mm / B 30 mm): normal patellar height by both the original range (0.54 to 1.06) and the commonly used categories (0.80 to 1.00).
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Distance A (inferior patellar articular surface to the tibial plateau line)
- Length B (patellar articular surface)
How this is calculated
Citation
Blackburne JS, Peel TE. A new method of measuring patellar height. J Bone Joint Surg Br. 1977;59(2):241-242. Cutoffs as tabulated in Rev Bras Ortop 2012 (PMC4799376) and Ann Med Surg 2022 (PMC9577418). Read the sources: Blackburne 1977 ↗, Rev Bras Ortop 2012 ↗, Ann Med Surg 2022 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.