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Assessment of Sagittal Plane Segmental Motion in the Lumbar Spine: A Comparison Between Distortion‐Compensated and Stereophotogrammetric Roentgen Analysis

Study Design. Sagittal plane translatory and rotatory motion was measured in 15 lumbar motion segments of 8 patients by distortion‐compensated and stereophotogrammetric Roentgen analysis. Objective. To compare measurement precision of the new distortion‐compensated Roentgen analysis protocol with that of the established Roentgen stereophotogrammetric technique under realistic clinical conditions. Summary of Background Data. Roentgen stereophotogrammetric analysis constitutes the most precise method available to assess segmental motion. Because of the invasive nature of the procedure, however, there is interest in alternative, noninvasive protocols suitable for studying larger patient cohorts. Methods. In 8 patients, segmental motion of 15 lumbar segments that had undergone previous spinal surgery was assessed from stereo views by using Roentgen stereophotogrammetric analysis. Sagittal plane segmental motion was assessed by distortion‐compensated Roentgen analysis. Sagittal plane translatory and rotatory motion data obtained by both methods were compared. Results. With respect to Roentgen stereophotogrammetric analysis, sagittal plane rotation was determined by distortion‐compensated Roentgen analysis with an error (standard deviation) of 1.4° and a mean difference of less than 0.05°. Sagittal plane translation was determined by distortion‐compensated Roentgen analysis, with an error of 1.25 mm and a mean difference 0.5 mm. Conclusion. Measurement precision of distortion‐compensated Roentgen analysis is slightly inferior to that of Roentgen stereophotogrammetric analysis but substantially higher than that of conventional protocols assessing lumbar segmental motion. If measurement precision is considered adequate and if a noninvasive technique is indicated, distortion‐compensated Roentgen analysis can be used to provide reliable motion data required for epidemiologic and clinical studies.