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Table 1 Advantages and disadvantages associated with radiographic and CT methods of rotation measurement

From: Vertebral rotation measurement: a summary and comparison of common radiographic and CT methods

Method Advantages Disadvantages
Cobb ▪ Simple procedure ▪ No means to quantify rotation from gradation scheme
  ▪ Little patient exposure to radiation (one anteroposterior radiograph) ▪ Distortion of spinous process tip in scoliotic vertebrae may decrease accuracy
   ▪ Limited visibility of spinous process on radiographs of vertebrae with large rotation
Nash-Moe ▪ Position of pedicles are less affected by intravertebral rotation; more reliable landmark for measuring rotation ▪ Provides over-estimation of rotation (can be adjusted by 10° as suggested by Drerup)
   ▪ Pedicles are poorly visible on vertebrae rotated severely or on spines with surgical instrumentation
Perdriolle ▪ Affordable ▪ Difficulty in making precise markings on radiographs – a 2 mm error corresponds to 5° rotation
  ▪ Non-invasive  
  ▪ Simple procedure  
  ▪ Little patient exposure to radiation (one anteroposterior radiograph) ▪ Reduced accuracy when measuring large degrees of rotation
  ▪ General findings report accurate measurements to within ± 5°  
Stokes ▪ Accounts for three-dimensionality of vertebra; similar accuracy to stereoradiograph ▪ Greater random error in comparison to methods involving marking of vertebral edges
  ▪ Little exposure to radiation  
  ▪ Simple measuring procedure  
Aaro-Dahlborn ▪ Better measurement accuracy even when measuring vertebrae tilted in the coronal and saggital planes ▪ More difficult to use for inexperienced observers due to less obvious landmark definitions
Ho ▪ Clearly defined reference points; simple procedure ▪ Less correlation to actual rotation value when measuring distorted and
  ▪ Better interobserver reliability in comparison to Aaro-Dahlborn method when assessing normal vertebrae tilted vertebrae; less applicable in realistic conditions