Kinematic evaluation of cervical sagittal balance and thoracic inlet alignment in degenerative cervical spondylolisthesis using kMRI

Publication date: Available online 26 April 2017
Source:The Spine Journal
Author(s): Permsak Pahpolak, Alexander Nazareth, Patrick C. Hsieh, Zorica Buser, Jeffrey C. Wang
Background contextT1 slope is a novel thoracic parameter used to assess cervical spine sagittal balance. Thoracic Index (TI) parameters including T1 slope and cervical sagittal alignment parameters may play an important role in degenerative cervical spondylolisthesis (DCS). Current literature regarding the relationship between TI and cervical sagittal alignment parameters in patients with DCS is limited.Purpose(1) To evaluate the T1 slope, cervical sagittal alignment, and Thoracic Inlet parameter in patients with DCS using kMRI, and (2) To find a correlation between the T1 slope, TI and other cervical sagittal parameters in DCS patients.DesignRetrospective kMRI study, Level IIIPatient sampleFifty-two DCS patients from 1,128 patients in cervical kMRI databaseOutcome measuresT1 slope, C2-7 angle, Sagittal Vertical Axis C2-7 (SVA C2-7), cranial tilt, cervical tilt, neck tilt, and Thoracic Inlet Angle (TIA).MethodsCervical spine kMRIs of 52 patients with DCS (mean age 51.7 ±SD) were analyzed in neutral, flexion and extension positions. DCS patients were divided in two groups: anterolisthesis (N=33) and retrolisthesis (N=19). Each listhesis group was sub-classified into grade 1 (slip 2-3mm) and grade 2 (slip > 3mm).ResultsGrade 2 retrolisthesis had the largest T1 slope followed by grade 1 retrolisthesis, grade 2, and grade 1 anterolisthesis. Significant differences were found between anterolisthesis and retrolisthesis in neutral position (P = 0.025). Flexion position had the largest T1 slope and showed significant difference with anterolisthesis in the neutral position (P=0.041). SVA C2-7 showed strong correlation with cranial tilt in all DCS groups and all positions.ConclusionIn our study T1 slope was larger in grade 2 DCS and the retrolisthesis group had larger T1 slope compared to anterolisthesis group. Presence of larger T1 slope was significantly correlated with larger cervical lordosis curvature. Furthermore, cranial tilt was strongly correlated with SVA C2-7.



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