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Classification of the Normal Variation in the Sagittal Alignment of the Human Lumbar Spine and Pelvis in the Standing Position

Roussouly, Pierre, MD*; Gollogly, Sohrab, MD*; Berthonnaud, Eric, PhD; Dimnet, Johanes, PhD

doi: 10.1097/01.brs.0000152379.54463.65

Study Design. A prospective radiographic study of 160 volunteers without symptoms of spinal disease was conducted.

Objectives. The objective of this study was to describe, quantify, and classify common variations in the sagittal alignment of the spine, sacrum, and pelvis.

Summary of Background Data. Previous publications have documented the high degree of variability in the sagittal alignment of the spine. Other studies have suggested that specific changes in alignment and the characteristics of the lumbar lordosis are responsible for degenerative changes and symptomatic back pain.

Methods. In the course of this study, anteroposterior and lateral radiographs of 160 volunteers in a standardized standing position were taken. A custom computer application was used to analyze the alignment of the spine and pelvis on the lateral radiographs. A four-part classification scheme of sagittal morphology was used to classify each patient.

Results. Reciprocal relationships between the orientation of the sacrum, the sacral slope, the pelvic incidence, and the characteristics of the lumbar lordosis were evident. The global lordotic curvature, lordosis tilt angle, position of the apex, and number or lordotic vertebrae were determined by the angle of the superior endplate of S1 with respect to the horizontal axis.

Conclusions. Understanding the patterns of variation in sagittal alignment may help to discover the association between spinal balance and the development of degenerative changes in the spine.

The lateral radiographs of 160 volunteers without spinal disease were analyzed. Common variations in the sagittal alignment of the spine, sacrum, and pelvis are described, quanti-fied, and classified with a four-part scheme of sagittal morphology. Reciprocal relationships between the pelvis and lumbar spine determine the characteristics of lumbar lordosis.

From the *Department of Orthopedic Surgery, Centre Des Massues, Lyon, France; and †Group of Applied Research in Orthopedics, Lyon, France.

Acknowledgment date: October 16, 2003. First revision date: January 12, 2004. Acceptance date: February 27, 2004.

The legal regulatory status of the device(s)/drug(s) that is/are the subject of this manuscript is not applicable in my country.

No 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.

Address correspondence and reprint requests to Pierre Roussouly, MD, Centre Des Massues, 92 rue Edmond Locard, 69005 Lyon, France. E-mail:

© 2005 Lippincott Williams & Wilkins, Inc.