Study Design. A radiographic study was conducted to investigate the accuracy of computer-assisted measurement of sacral morphology in a population with developmental L5–S1 spondylolisthesis.
Objective. The purpose of this study was to evaluate the inter- and intraobserver variability of computer measurements of sacral morphology.
Summary and Background Data. Recent studies have shown differences in sacral morphology among patients with spondylolisthesis. The sacral table angle (STA) is a fundamental sacral anatomic parameter that is specific and constant to each individual, while the S1 superior and S2 inferior angles are defined as anatomic measures specific to S1 and S2. Sacral kyphosis measured by Ferguson or Cobb method has also been used to evaluate the sagittal shape of the sacrum. Currently, computerized measures are gaining popularity for the study of sagittal balance, but their reliability especially in sacral morphology has never been properly evaluated.
Methods. The standing lateral radiographs of 30 adolescents were randomly selected from the radiographic database of our institution: 10 radiographs of asymptomatic individuals, 10 of subjects with low grade L5–S1 spondylolisthesis and 10 with high grade L5–S1 developmental spondylolisthesis. Three surgeons measured sacral morphologic variables on the 30 radiographs at 2 occasions, with a 15 days interval between the 2 sessions, using a computer assisted technique. Intraclass correlation coefficients (ICCs) were used for statistical analysis.
Results. The ICC values measured within observers varied between 0.951 to 0.995, whereas the ICC measured between observers varied between 0.957 to 0.995. There was a slight decrease of the ICC measured in the high grade L5–S1 spondylolisthesis group compared to the normal subjects. However, the difference was not statistically significant.
Conclusion. These results confirm the reliability and repeatability of computer-assisted angular measurement of sacral morphology in subjects with L5–S1 spondylolisthesis, even in the presence of lumbosacral junction dysplasia. The use of computerized measurements can be recommended for the evaluation of the sagittal sacral anatomy in future clinical and research studies.
Recent studies have showed differences in sacral morphology in patients with spondylolisthesis. However, computerized measures of sacral morphology have never been properly evaluated for accuracy. The results of this study confirm the reliability and repeatability of computer-assisted angular measurement of sacral morphology in L5–S1 spondylolisthesis patients even in the presence of lumbosacral junction dysplasia.
From the *Research Center, Sainte-Justine University Hospital Center, Montréal, Québec, Canada; †Department of Orthopaedic Surgery, Université de Montréal, Montréal, Québec, Canada; and ‡Department of Mechanical Engineering, École Polytechnique, Montréal, Québec, Canada.
Acknowledgment date: January 30, 2009. Revision date: May 4, 2009. Acceptance date: May 7, 2009.
The legal regulatory status of device(s)/drug(s) that is/are the subject of this manuscript is not applicable in the author's country.
Corporate/Industry funds were received in support of this work. One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript: e.g., honoraria, gifts, consultancies.
Supported by MENTOR, a strategic training program of the Canadian Institutes of Health Research, FREOM (fondation de recherche et d'éducation en orthopédie de Montréal) and in part by the Spinal Deformity Study Group and an educational noncommercial research grant from Medtronic Sofamor Danek.
Address correspondence and reprint requests to Hubert Labelle, MD, Division of Orthopaedics, Sainte-Justine University Hospital Center, 3175 Côte-Sainte-Catherine, Montréal, Québec, Canada H3T 1C5; E-mail: hubert.labelle@recherche-ste-justine.qc.ca
