Johnson and Strom Classification (Adult-Acquired Flatfoot)
Stages adult-acquired flatfoot deformity (posterior tibial tendon dysfunction) by Johnson and Strom, with the Myerson stage IV.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Hindfoot deformity
- Present and flexible (correctable)
- Ankle
- No ankle valgus
Result: Johnson and Strom stage II: an elongated posterior tibial tendon with a flexible flatfoot deformity.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Hindfoot deformity
- Ankle
- Single-leg heel rise
- Too many toes sign
- Radiographs
How this is calculated
Citation
Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop Relat Res. 1989;(239):196-206. Stage IV: Myerson MS. Instr Course Lect. 1997;46:393-405. Criteria as tabulated in Abousayed MM et al. Clin Orthop Relat Res. 2016;474(2):588-593. Read the sources: Johnson 1989 ↗, Abousayed 2016 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.