Non-fusion segment disease after the anterior cervical arthrodesis：a retrospective study

GUO Bing-lu; SONG Ke-ran; CHEN Qiao-ling; CHEN Zeng-hai; WANG Da-peng; WANG Hui; JIN Pei; TANG Jia-guang

doi:10.3969/j.issn.2095-252X.2016.08.012

Abstract：Objective To investigate the incidence and causes of non-fusion segment disease ( NFSD ), both adjacent and non-adjacent to the fused segment, after the anterior cervical arthrodesis.Methods This is a retrospective cohort study. Between January 1998 and January 2011, 171 patients who had anterior cervical decompression and fusion for the intervertebral disc herniation and cervical spondylosis were followed clinically. There were 97 males and 74 females, and the average age at the operation was ( 51.90 ± 9.28 ) years ( range: 31 - 72 years ). We evaluated the correlation between the incidence of symptomatic non-fusion segment disease and the following clinical parameters ( age at the operation, fusion levels ) and radiological parameters ( preoperative and postoperative cervical spine alignment, Pavlov’s ratio at the C5 level, and preoperative existence of a non-fusion segment degeneration on magnetic resonance imaging ).Results Of the 171 patients reviewed, 16 patients had non-fusion segment disease ( 9.36% ), 12 patients had adjacent segment disease and 4 had non-adjacent segment disease. Postoperative cervical lordosis in the non-fusion segment disease group was signiifcantly smaller than that of the disease-free group [ ( 7.38 ± 12.37 ) ° vs. ( 17.26 ± 9.75 ) °,P < 0.001 ]. Fusion levels in the NFSD group were 1.63 whereas 2.27 in disease-free group (P = 0.002 ). The incidence of disc degeneration in non-fused segments was more severe in the NFSD group than in the disease-free group [ ( 2.63 ± 0.62 )vs. ( 1.62 ± 0.99 ), P = 0.008 ].Conclusions The incidence of symptomatic non-fusion segment disease after the anterior cervical arthrodesis has multifactorial causes. Postoperative cervical lordosis, disc degeneration in non-fusion segments, and the number of fusion levels are all factors in the incidence of NFSD.