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2008 Young Investigator Award: The Role of Congenitally Fused Cervical Segments Upon the Space Available for the Cord and Associated Symptoms in Klippel-Feil Patients

Samartzis, Dino DSc, MSc, Dip EBHC*‡; Kalluri, Prakasam MD§; Herman, Jean RN, MS, MBA; Lubicky, John P. MD; Shen, Francis H. MD‡¶

doi: 10.1097/BRS.0b013e3181753ca6
Cervical Spine

Study Design. A prospective radiographic and retrospective clinical chart review.

Objective. This study evaluated the role of congenitally fused cervical segments in relation to the space available for the cord (SAC) and associated cervical spine-related symptoms (CSS) in patients with Klippel-Feil Syndrome (KFS).

Summary of Background Data. KFS is a developmental disorder presenting with congenital fusion of at least 2 cervical vertebrae. The effects of congenitally fused cervical segments in relation to the SAC and associated symptoms in KFS patients remain speculative and have not been thoroughly addressed in the literature.

Methods. At a single institution, a prospective radiographic and clinical evaluation of 29 KFS patients was conducted. Based on plain radiographs, assessment of the SAC consisted of the posterior atlantodens interval, the midvertebral body SAC (C2–C7), and the interbody SAC (C2–C3–C7–T1). Vertebral body width (VBW) from C2 to C7 and the presence of occipitalization (O-C1) were also noted. Torg ratios were obtained at each level. Demographics, medical history, and the presence of CSS were noted based on clinical chart review.

Results. Ten males and 19 females were reviewed (mean age, 13.4 years). A significant correlation was noted between the overall VBWs to the number of fused segments, age, and skeletal maturity (P < 0.05), but not to sex-type, O-C1, and SAC levels (P > 0.05). In the presence of a fused segment, individualized SAC levels tended to have greater canal dimensions and cephalad/caudal VBWs were less. Cephalad and caudal Torg ratios in relation to a segment were greater in all fused segments, and with 4 or greater fused segments (P < 0.05). Number of levels fused, sex-type, skeletal maturity, and O-C1 were not significantly associated with the presence of symptoms (P > 0.05). Symptomatic patients had smaller VBWs than nonsymptomatic patients (P = 0.027) and an overall decrease in SAC at the interbody disc level, primarily at C6–C7 (P > 0.05). Smaller Torg ratios were noted in symptomatic patients, specifically myelopathic patients.

Conclusion. Congenital fusion in KFS may arrest the normal vertebral development, which may affect appositional bone growth. Such effects on the VBW could potentially contribute to an increase in the SAC. Such a development may delay neurologic compromise stemming from the congenital fusion process and subsequent degenerative manifestations.

Because of the congenital fusion process associated with Klippel-Feil Syndrome, a wasp-waist deformity or decreased width of the vertebral body morphology is noted, which may alter appositional bone growth and allow an increase in size for the space available for the cervical cord. Such a development may delay neurologic compromise stemming from degenerative manifestations.

From the *Department of Orthopaedics, Erasmus University, Rotterdam, The Netherlands; ‡Shriners Hospitals for Children, Chicago, IL; §Colonial Orthopedics, Colonial Heights, VA; ∥Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN; and ¶Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA.

Acknowledgment date: May 23, 2006. First revision date: October 31, 2006. Second revision date: December 15, 2006. Third revision date: May 1, 2007. Fourth revision date: May 31, 2007. Acceptance date: June 1, 2007.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Francis H. Shen, MD, Department of Orthopaedic Surgery, University of Virginia, P.O. Box 800159, Charlottesville, VA 22908-0159; E-mail:

© 2008 Lippincott Williams & Wilkins, Inc.