Anterior cervical decompression and fusion (ACDF) is considered a standard surgical treatment to degenerative discogenic diseases. Lately, the question arises whether or not ACDF significantly influences the progression of adjacent disc degeneration (ADD). The etiology of ADD is obscure and it has not been fully understood whether ADD is a consequence of fusion or it represents the aging pathway of the degenerative cervical process, thus making it a controversial topic [1-3]. There have been several discussions about the possibility of ACDF altering biomechanical conditions at adjacent segments, therefore resulting in increased load and excessive motion [3,4]. The purpose of this study was to compare the cervical segmental motion pre- and post-ACDF using novel 3D analytical techniques. Nine patients (2F/7M, mean age: 54.1 years, range 36–76 y.o.) underwent ACDF due to symptomatic cervical degenerative discogenic disease. One-level ACDF was performed in 4 patients, whereas 2-level ACDF was done in five, using cylindrical titanium porous cage implants. Pre- and post (postoperative periods ranged from 11-months, 25 days to 12-months, 22 days, mean postoperative period: 12.09 months) surgery, dynamic-CT examinations were conducted in neutral, flexion and extension positions. Subject-based 3D CT models were created for segmental motion analysis (Fig. 1). Six-degrees-of-freedom 3D segmental movements were analyzed using a validated Volume-Merge methods (accuracy: 0.1 mm in translation, 0.2°in rotation) [5]. The segmental translation was evaluated by the segmental translations of gravity centers of endplates (Fig. 2). Disc-height distribution was measured using a custom-written Visual C++ routine implementing a lease-distance calculation algorithm. The mean translation distance was calculated for the each adjacent level (Fig. 2). Differences of segmental motions and mean disc height between pre- and post-surgery at each level were compared by the Wilcoxon signed rank test. Results were presented mean±SEM.Introduction
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