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Lamina Horizontalization and Facet Tropism as the Risk Factors for Adjacent Segment Degeneration After PLIF

Okuda, Shinya, MD*; Oda, Takenori, MD*; Miyauchi, Akira, MD*; Tamura, Satoru, MD*; Hashimoto, Yoshichika, MD*; Yamasaki, Shinya, MD*; Haku, Takamitsu, MD*; Kanematsu, Fumiaki, MD*; Ariga, Kenta, MD; Ohwada, Tetsuo, MD; Aono, Hiroyuki, MD; Hosono, Noboru, MD; Fuji, Takeshi, MD; Iwasaki, Motoki, MD§

doi: 10.1097/BRS.0b013e31817bb9c2
Clinical Case Series
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Study Design. A retrospective case-control study.

Objective. To clarify associations between both lamina horizontalization and facet tropism and adjacent segment degeneration (ASD).

Summary of Background Data. We have previously reported coexistence of lamina horizontalization and facet tropism adjacent to the cranial fusion segment as risk factors for ASD.

Methods. Subjects comprised 20 patients who underwent additional surgery for ASD after L4/5 posterior lumbar interbody fusion (PLIF) for L4 degenerative spondylolisthesis. Patients who underwent additional surgery for ASD (ASD group) were divided into 2 groups according to the duration until additional surgery: early group (n = 13), additional surgery ≤3 years after primary surgery; and late group (n = 7), additional surgery >3 years after primary surgery. As a control group, 20 age- and sex-matched patients who underwent L4/5 PLIF and could be followed for ≥5 years without ASD were selected. Lamina inclination angle at L3 and facet tropism at L3/4 in each group were measured 3 times by 3 individuals blinded to clinical results. Associations between clinical results and these risk factors and influences of these factors for periods up to the occurrence of ASD were investigated.

Results. All ASD was observed in the cranial adjacent segment and the most common condition at additional surgery was spondylolisthesis (n = 15, 75%). Lamina inclination angle was significantly higher in the ASD group than in the control group. ASD was observed in 86% of patients with lamina inclination >130°. In addition, facet tropism was more significant in the early group than in the late and control groups. ASD was observed ≤3 years after primary surgery in all patients with both lamina inclination >130° and facet tropism >10°.

Conclusion. Preexisting lamina horizontalization at the cranial fusion segment seems to affect ASD, and coexistence of lamina horizontalization and facet tropism seems to accelerate ASD after PLIF.

Preexisting lamina horizontalization at the cranial fusion segment seems to affect adjacent segment degeneration. Further, coexistence of the lamina horizontalization and facet tropism seems to rapidly accelerate the adjacent segment degeneration after posterior lumbar interbody fusion. Adjacent segment degeneration was observed ≤3 years after primary surgery in all patients with both lamina inclination >130° and facet tropism >10°.

From the *Department of Orthopaedic Surgery, Osaka Rosai Hospital, Osaka; †Department of Orthopaedic Surgery, Kansai Rosai Hospital, Hyogo; ‡Department of Orthopaedic Surgery, Osaka Koseinenkin Hospital; and §Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.

Acknowledgment date: October 18, 2007. First revision date: January 23, 2008. Acceptance date: February 4, 2008.

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 Shinya Okuda, Department of Orthopaedic Surgery, Osaka Rosai Hospital, 1179-3 Nagasone-cho, Kita-ku, Sakai, Osaka, 591-8025, Japan; E-mail: okuda-s@umin.ac.jp

© 2008 Lippincott Williams & Wilkins, Inc.