The validity and reliability of measurements in spinal deformities: a critical appraisal

Quantitative measurement of spinal deformity is the preliminary step in order to plan a therapeutic regimen. The most commonly used methods and, for this matter, practically any measurement methods, may have several sources of errors, namely: a. errors in taking a radiograph; b. errors intrinsic to the measurement method; c. errors due to anatomical deformity of the vertebrae; d. observer errors in measurement technique. These are discussed, and suggestions are given to minimize them.