Joint Space Narrowing Index Calculator

1. Baseline Mean Width
Baseline Mean = (Baseline Medial Width + Baseline Lateral Width) / 2

2. Current Mean Width
Current Mean = (Current Medial Width + Current Lateral Width) / 2

3. Narrowing Percentage
Narrowing % = ((Baseline Mean - Current Mean) / Baseline Mean) × 100

4. Compartment Balance
Compartment Balance = |Medial Narrowing % - Lateral Narrowing %|

5. Annual Narrowing Rate
Annual Rate = Narrowing % / Years Elapsed

6. Adjusted Progression Score
Progression Score = (Imaging Weight × Annual Rate) + (Pain Weight × Pain Score × 5) + (Stiffness Weight × Stiffness Score × 5)

7. Joint Space Narrowing Index
JSN Index = (Narrowing % × 0.7) + (Compartment Balance × 0.1) + (Progression Score × 0.2)

This index is a structured educational model for comparing repeated measurements. It is not an official diagnostic standard.

1. Enter baseline medial and lateral joint widths from the earlier imaging study.
2. Enter current medial and lateral widths from the newer study.
3. Add the time gap in years between both measurements.
4. Optionally enter pain and stiffness scores for a broader tracking view.
5. Adjust the weighting fields if your review model uses different emphasis.
6. Click Calculate to show the result section above the form.
7. Review the graph, interpretation, and severity band.
8. Use the CSV or PDF buttons to save the current output.