Reimers Migration Percentage (Hip)
Reimers migration percentage / hip migration index (Reimers 1980): MP = (a / b) x 100, where a = femoral-head width lateral to Perkin's line and b = total femoral-head width (mm).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Femoral-head width lateral to Perkin's line, a
- 20 mm
- Total femoral-head width, b
- 50 mm
Result: Reimers MP 40% — hip subluxated.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Thresholds
- <= 33% normal/contained; > 33% subluxated (hip-surveillance referral); ~90-100% dislocated.
What you enter
- Femoral-head width lateral to Perkin's line, a (mm)
- Total femoral-head width, b (mm)
How this is calculated
- Formula
- MP = (a / b) x 100, a = femoral-head width lateral to Perkin's line, b = total femoral-head width (mm).
Reimers J. The stability of the hip in children: a radiological study of the results of muscle surgery in cerebral palsy. Acta Orthop Scand Suppl. 1980;184:1-100. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.