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 < or =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 > or =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 degrees . In addition, facet tropism was more significant in the early group than in the late and control groups. ASD was observed < or =3 years after primary surgery in all patients with both lamina inclination >130 degrees and facet tropism >10 degrees . 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.
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 < or =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 > or =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 degrees . In addition, facet tropism was more significant in the early group than in the late and control groups. ASD was observed < or =3 years after primary surgery in all patients with both lamina inclination >130 degrees and facet tropism >10 degrees . 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.
Authors: Salvador Fuster; Jaime Jesús Martínez-Anda; Sergio Antonio Castillo-Rivera; Caribay Vargas-Reverón; Eduard Tornero Journal: Asian Spine J Date: 2021-06-17