For a study, researchers sought to develop and discover patient-related variables that influence neighboring segment kinematics following anterior cervical discectomy and fusion (ACDF), as assessed by biplane radiography. It is possible that multiple factors contribute to adjacent segment disease (ASD) pathogenesis. Few studies have sought to connect patient variables with mechanical changes in the spine that may explain how ASD develops, despite previous research on connections between patient factors and ASD. Previous studies manually evaluated intervertebral motion from static flexion/extension radiographs, but since manual measures were inaccurate, they did not capture intervertebral motion during rotation. Patients received continuous cervical spine flexion/extension and axial rotation motions recorded at 30 pictures per second in a dynamic biplane radiography system before surgery and 1 year after ACDF. A proven tracking procedure was used to match digitally reconstructed radiographs made from subject-specific computed CT scans to the biplane radiographs. The results of this tracking procedure were used to compute dynamic kinematics and preoperative disc height. A disc bulge was assessed using magnetic resonance imaging prior to surgery. Age, sex, BMI, smoking status, diabetes, psychiatric history, the presence of a triggering event, and the duration of the symptoms were all gathered from the patient. To determine patient characteristics connected to changes in adjacent segment kinematics at 1 year postoperative, multivariate linear regression was used. Preoperative and postoperative exams were successfully completed by 63 individuals. The change in the superior adjacent segment’s range of motion following surgery was predicted by the disc bulge and height in the superior adjacent segment. Smoking history, the use of psychiatric drugs, and the bulge in the inferior adjacent segment disc all predicted changes in the inferior adjacent segment’s range of motion after surgery. After ACDF, adjacent segment motion was found to be less when there was prior adjacent segment disc degeneration, as seen by disc height and disc bulge; however, subsequent adjacent segment motion was found to be more after ACDF when there was no pre-existing adjacent disc degeneration. These results offered in vivo proof that early instability and late stabilization were important components of disc degeneration’s pathogenesis.

 

Source: journals.lww.com/spinejournal/Abstract/2022/09010/In_Vivo_Evidence_of_Early_Instability_and_Late.7.aspx