Leg Length Discrepancy Measurement

Leg-Length Discrepancy Measurement (LLDM) by orthogonal projection onto pelvic baseline L1.

Landmarks (cm)

Rounding to 4 decimals; internal math in full precision. Slope convention: cL3 = -(-1/cL1).

Answer


    


    

      
Reason why

      

    


    

      
Figure (photo with annotations)

      

        LLDM illustration (archived Agfa page)
        

          

            
Computed results

            
d53=?, d64=?, dCm=?

            
LLDAlarm: ?

          

          

            
Notes

            
Values overlay the image. Landmarks drive the math.

          

        

      

    


    

      
Check (harness)

      

        Each line: p1x,p1y,p2x,p2y,p3x,p3y,p4x,p4y[,expected_dCm[,expected_alarm]].
        Expected columns are optional; when present they’re validated (|Δ| < 0.001 cm).