Method of Taillard for Calculating the Percent Slip of L5 in Spondylolisthesis

 

Radiograph: lateral view of lower lumbar spine and sacrum

 

Lines to draw:

(1) line along the posterior aspect of the sacral vertebral bodies

(2) parallel line through the anterior border of S1

(3) parallel line through posterior aspect of L5 vertebral body

 

distance A =

= distance between line #1 and line #3 in mm

 

distance B =

= distance between line #1 and line #2 in mm

 

percent slip =

= (distance A) / (distance B) * 100%

 

Interpretation:

• The normal percent slip is close to 0%.

• As spondylolithesis progresses the percent slip increases.