A 10-year Long-term Clinical Study Of Cervical Disc Replacement For Degenerative Cervical Spondylosis

Objectives: To evaluate the long-term clinical efficacy of cervical disc replacement(CDR)and anterior cervical discectomy and fusion(ACDF)in the treatment of degenerative cervical spondylosis.Methods: To retrospectively analysis of the clinical date of patients with degenerative cervical spondylosis treated with CDR and ACDF at our hospital from January 2009 to December 2012.There were 64 patients in the CDR group with Discover prosthesis,23 males and 41 females,with a mean age of 46.45±6.59 years(32-58 years),and the lesion segments were: 1 patient with C3-C4,3 patients with C4-C5,49 patients with C5-C6,6patients with C6-C7,2 patient with C3-C4 and C4-C5,and 3 patient with C4-C5 and C5-C6.There were 278 patients in the ACDF group.The ACDF group was divided into two subgroups according to the choice of material,172 patients in the Conventional Cage-Plate group and 106 patients in the Zero-Profile group.There were 79 males and 93 females in the Conventional Cage-Plate group,with a mean age of 46.63 ± 6.41 years(33-64 years)and lesion segments: 3 patients with C3-C4,15 patients with C4-C5,114 patients with C5-C6,21 patients with C6-C7,8 patients with C3-C4 and C4-C5,and 11 patients with C4-C5 and C5-C6.There were 42 males and 64 females in the Zero-Profile group,with a mean age of 46.59 ± 5.81 years(31-61 years),and the lesion segments were:2 patients with C3-C4,12 patients with C4-C5,71 patients with C5-C6,10 patients with C6-C7,7 patients with C3-C4 and C4-C5,and 4 patients with C4-C5 and C5-C6.Japan Orthopedic Association(JOA),visual analogue scale(VAS)and neck disability index(NDI)were used to assess neurological function and before surgery,3 months after surgery,3,5 years after surgery,and at the last follow-up.The Bazaz score was used to assess the postoperative dysphagia in each group.Cervical spine radiographs、CT scan and MRI were used to measure and evaluate cervical lordosis angle,the range of motion(ROM)and heterotopic ossification(HO)at the index level of the CDR group,and adjacent segments degeneration(ASD)at the last follow-up in each groups.Results: The mean follow-up time was 139.47±10.94 months in the CDR group,137.02±9.40 months in the Conventional Cage-Plate group,and 138.18±10.22 months in the Zero-Profile group,with no statistically significant comparison of the three groups(P>0.05).The JOA,VAS-Arm,VAS-Neck and NDI obtained significant improvement in all three groups at each postoperative follow-up time point compared with the preoperative period(P>0.05),which were statistically significant when compared with the preoperative period in the same group(P<0.05).The results were statistically significant in the CDR group at 3 and 5 years postoperatively compared with the preoperative cervical lordosis angle(P<0.05);the cervical lordosis angle at the last follow-up was not statistically significant when compared with the preoperative one(P>0.05);the cervical lordosis angle at the same follow-up time was not statistically significant between the three groups at preoperative,3 months,5 years and the last follow-up(P>0.05);At the 3-year postoperative follow-up,the comparison of the cervical lordosis angle among the three groups was statistically significant(P<0.05).ROM at the index level in the CDR group was statistically significant at all follow-up time points compared with preoperative(P<0.05),with significant increases in ROM at the index level at 3 months,3 years,and 5years postoperatively compared with preoperative,and partial loss of surgical segment ROM at the final follow-up compared with preoperative.At the immediate postoperative period,the incidence of dysphagia was 7.8% in the CDR group,19.1% in the Conventional Cage-Plate group,and 6.6% in the Zero-Profile group,with a statistically significant comparison of dysphagia between the three groups(P=0.020),and no statistically significant comparison of dysphagia between the three groups at 3 months,3years,5 years,and at the final follow-up after surgery(P>0.05).At the final follow-up,the incidence of HO at the index level in the CDR group was 73.9%,including 6 cases of Mc Afee grade I,9 cases of grade II,27 cases of grade III,and 9 cases of grade IV,with mild HO accounting for 21.7% and severe HO accounting for 52.2%.The comparison of HO at the index level in the CDR group at the final follow-up with each other follow-up time was statistically significant(P<0.05).The radiographic ASD at the last follow-up in the three groups was 39.1% in the CDR group,68.6% in the Conventional Cage-Plate group,and 41.0% in the Zero-Profile group,respectively,and the comparison of radiographic ASD in the three groups was statistically significant(P=0.001).According to the assessment criteria of symptomatic ASD,7.8% of patients in the CDR group,21.5% in the Conventional Cage-Plate group,and 15.1% in the Zero-Profile group.The comparison of symptomatic ASD at the final follow-up of the three groups was statistically significant(P=0.037).The rate of secondary surgery due to symptomatic ASD was 12.2% of patients in the Conventional Cage-Plate group,1.9% in the Zero-Profile group,and 0% in the CDR group,with a statistically significant comparison of the rate of secondary surgery due to symptomatic ASD at the end follow-up of the three groups(P=0.001).Conclusions: CDR can be used as an alternative treatment technique to ACDF for degenerative cervical spondylosis.Long-term follow-up found satisfactory clinical outcomes for both CDR and ACDF.the greatest advantage of CDR is the preservation of segmental ROM and reduction of ASD,but inevitably there is a partial loss of ROM at the index level due to HO,and the study suggests that we should be strict about the indications for CDR.