***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND CONTEXT Cervical total disc replacement ( TDR ) is intended to address radicular pain and preserve functional motion between two vertebral bodies in patients with symptomatic cervical disc disease ( SCDD ) . PURPOSE The purpose of this trial is to compare the safety and efficacy of cervical TDR , ProDisc-C ( Synthes Spine Company , L.P. , West Chester , PA ) , to anterior cervical discectomy and fusion ( ACDF ) surgery for the treatment of one-level SCDD between C3 and C7 . STUDY DESIGN / SETTING The study was conducted at 13 sites . A noninferiority design with a 1:1 r and omization was used . PATIENT SAMPLE Two hundred nine patients were r and omized and treated ( 106 ACDF ; 103 ProDisc-C ) . OUTCOME MEASURES Visual analog scale ( VAS ) pain and intensity ( neck and arm ) , VAS satisfaction , neck disability index ( NDI ) , neurological exam , device success , adverse event occurrence , and short form-36 ( SF-36 ) st and ardized question naires . METHODS A prospect i ve , r and omized , controlled clinical trial was performed . Patients were enrolled and treated in accordance with the US Food and Drug Administration ( FDA ) -approved protocol . Patients were assessed pre- and postoperatively at six weeks , 3 , 6 , 12 , 18 , and 24 months . RESULTS Demographics were similar between the two patient groups ( ProDisc-C : 42.1+/-8.4 years , 44.7 % males ; Fusion : 43.5 + /- 7.1 years , 46.2 % males ) . The most commonly treated level was C5-C6 ( ProDisc-C : 56.3 % ; Fusion=57.5 % ) . NDI and SF-36 scores were significantly less compared with presurgery scores at all follow-up visits for both the treatment groups ( p<.0001 ) . VAS neck pain intensity and frequency as well as VAS arm pain intensity and frequency were statistically lower at all follow-up timepoints compared with preoperative levels ( p<.0001 ) but were not different between treatments . Neurologic success ( improvement or maintenance ) was achieved at 24 months in 90.9 % of ProDisc-C and 88.0 % of Fusion patients ( p=.638 ) . Results show that at 24 months postoperatively , 84.4 % of ProDisc-C patients achieved a more than or equal to 4 degrees of motion or maintained motion relative to preoperative baseline at the operated level . There was a statistically significant difference in the number of secondary surgeries with 8.5 % of Fusion patients needing a re-operation , revision , or supplemental fixation within the 24 month postoperative period compared with 1.8 % of ProDisc-C patients ( p=.033 ) . At 24 months , there was a statistically significant difference in medication usage with 89.9 % of ProDisc-C patients not on strong narcotics or muscle relaxants , compared with 81.5 % of Fusion patients . CONCLUSIONS The results of this clinical trial demonstrate that ProDisc-C is a safe and effective surgical treatment for patients with disabling cervical radiculopathy because of single-level disease . By all primary and secondary measures evaluated , clinical outcomes after ProDisc-C implantation were either equivalent or superior to those same clinical outcomes after Fusion OBJECT There are now 3 r and omized , multicenter , US FDA investigational device exemption , industry-sponsored studies comparing arthroplasty with anterior cervical discectomy and fusion ( ACDF ) for single-level cervical disease with 2 years of follow-up . These 3 studies evaluated the Prestige ST , Bryan , and ProDisc-C artificial discs . The authors analyzed the combined results of these trials . METHODS A total of 1213 patients with symptomatic , single-level cervical disc disease were r and omized into 2 treatment arms in the 3 r and omized trials . Six hundred twenty-one patients received an artificial cervical disc , and 592 patients were treated with ACDF .  In the three trials , 94 % of the arthroplasty group and 87 % of the ACDF group have completed 2 years of follow-up . The authors analyzed the 2-year data from these 3 trials including previously unpublished source data . Statistical analysis was performed with fixed and r and om effects models . RESULTS The authors ' analysis revealed that segmental sagittal motion was preserved with arthroplasty ( preoperatively 7.26 ° and postoperatively 8.14 ° ) at the 2-year time point . The fusion rate for ACDF at 2 years was 95 % . The Neck Disability Index , 36-Item Short Form Health Survey Mental , and Physical Component Summaries , neck pain , and arm pain scores were not statistically different between the groups at the 24-month follow-up . The arthroplasty group demonstrated superior results at 24 months in neurological success ( RR 0.595 , I(2 ) = 0 % , p = 0.006 ) . The arthroplasty group had a lower rate of secondary surgeries at the 2-year time point ( RR 0.44 , I(2 ) = 0 % , p = 0.004 ) . At the 2-year time point , the reoperation rate for adjacent-level disease was lower for the arthroplasty group when the authors analyzed the combined data set using a fixed effects model ( RR 0.460 , I(2 ) = 2.9 % , p = 0.030 ) , but this finding was not significant using a r and om effects model . Adverse event reporting was too heterogeneous between the 3 trials to combine for analysis . CONCLUSIONS Both anterior cervical discectomy and fusion as well as arthroplasty demonstrate excellent 2-year surgical results for the treatment of 1-level cervical disc disease with radiculopathy . Arthroplasty is associated with a lower rate of secondary surgery and a higher rate of neurological success at 2 years . Arthroplasty may be associated with a lower rate of adjacent-level disease at 2 years , but further follow-up and analysis are needed to confirm this finding Study Design . Prospect i ve r and omized clinical trial . Objective . Determine the reasons for , and rates of , secondary surgical intervention up to 5 years at both the index and adjacent levels in patients treated with cervical total disc replacement ( TDR ) or anterior cervical discectomy and fusion ( ACDF ) . Patients undergoing TDR received ProDisc-C.  Summary of Background Data . Several outcome -based prospect i ve , r and omized clinical trials have shown cervical TDR to be equivalent , if not superior , to fusion . The ability of TDR to allow decompression while maintaining motion has led many to suggest that adjacent-level degeneration and reoperation rates may be decreased when compared with fusion . Methods . A total of 209 patients were treated and r and omized ( TDR , n = 103 ; ACDF , n = 106 ) at 13 sites . A secondary surgical intervention at any level was considered a reoperation . Results . At 5 years , patients who received ProDisc-C had statistically significant higher probability of no secondary surgery at the index and adjacent levels than patients who underwent ACDF ( 97.1 % vs. 85.5 % , P = 0.0079 ) . No reoperations in patients who received ProDisc-C were performed for implant breakages or device failures . For patients who underwent ACDF , the most common reason for reoperation at the index level was pseudarthrosis , and for patients who underwent both ACDF and TDR , the most common reason for adjacent-level surgery was recurrent neck and /or arm pain . Conclusion . Five-year follow-up of a prospect i ve r and omized clinical trial revealed 5-fold difference in reoperation rates when comparing patients who underwent ACDF ( 14.5 % ) with patients who underwent TDR ( 2.9 % ) . These findings suggest the durability of TDR and its potential to slow the rate of adjacent-level disease . Level of Evidence : OBJECT The purpose of this study was to evaluate the long-term results of  cervical total disc replacement ( TDR ) and anterior cervical discectomy and fusion ( ACDF )  in the treatment of single-level cervical radiculopathy . METHODS The results of 2 separate prospect i ve , r and omized , US FDA Investigational Device Exemption pivotal trials ( Bryan Disc and Kineflex|C ) from a single investigational site were combined to evaluate outcomes at long-term follow-up . The primary clinical outcome measures included the Neck Disability Index ( NDI ) , visual analog scale ( VAS ) , and neurological examination .  Patients were r and omized to receive cervical TDR in 2 separate prospect i ve , r and omized studies using the Bryan Disc or Kineflex|C cervical artificial disc compared with ACDF using structural allograft and an anterior plate . Patients were evaluated preoperatively ; at 6 weeks ; at 3 , 6 , and 12 months ; and then yearly for a minimum of 48 months . Plain radiographs were obtained at each study visit . RESULTS A total of 74 patients were enrolled and r and omly assigned to either the cervical TDR ( n = 41 ) or ACDF ( n = 33 ) group . A total of 63 patients ( 86 % ) completed a minimum of 4 years follow-up . Average follow-up was 6 years ( 72 months ) with a range from 48 to 108 months . In both the cervical TDR and ACDF groups , mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the minimum 48-month follow-up ( p < 0.001 ) . Similarly , the median VAS pain scores improved significantly by 6 weeks and remained significantly improved throughout the minimum 48-month follow-up ( p < 0.001 ) . There were no significant differences between groups in mean NDI or median VAS scores . The range of motion ( ROM ) in the cervical TDR group remained significantly greater than the preoperative mean , whereas the ROM in the ACDF group was significantly reduced from the preoperative mean . There was significantly greater ROM in the cervical TDR group compared with the ACDF group . There were 3 reoperations ( 7.3 % ) at index or adjacent levels in the cervical TDR group ; all were cervical laminoforaminotomies . There were 2 adjacent-level reoperations in the cervical TDR group ( 4.9 % ) . There was 1 reoperation ( 3.0 % ) in the ACDF group at an index or adjacent level ( a second ACDF at the adjacent level ) . There was no statistically significant difference in overall reoperation rate or adjacent-level reoperation rate between groups . CONCLUSIONS Both cervical TDR and ACDF groups showed excellent clinical outcomes that were maintained over long-term follow-up . Both groups showed low index-level and adjacent-level reoperation rates . Both cervical TDR and ACDF appear to be viable options for the treatment of single-level cervical radiculopathy BACKGROUND The published two-year results of the pivotal U.S. Food and Drug Administration investigational device exemption trial with the use of the Bryan cervical disc arthroplasty compared with anterior cervical discectomy with fusion for treating single-level degenerative cervical disc disease revealed a significantly superior overall success rate in the arthroplasty group . The purpose of this study was to evaluate the midterm safety and effectiveness of the Bryan disc as an alternative to arthrodesis following anterior cervical discectomy . METHODS A prospect i ve , multicenter r and omized clinical trial was undertaken for the treatment of persistent radiculopathy or myelopathy due to single-level cervical disc herniations or spondylosis . Patients were r and omized to treatment with either the Bryan disc ( the arthroplasty group ; 242 patients ) or anterior cervical discectomy and fusion ( the fusion group ; 221 patients ) . Patients completed preoperative and postoperative self- assessment forms at specified intervals and had radiographs made preoperatively , at six weeks , and at three , six , twelve , twenty-four , and forty-eight months after surgery . The primary outcome measure was overall success , a composite variable of safety and efficacy measures . Numerous secondary measures were assessed . The follow-up data for up to twenty-four months have been previously published . We report in the present study the forty-eight-month data collected on 181 patients who received the Bryan disc and 138 patients who underwent anterior cervical discectomy and fusion .  RESULTS The study groups were demographically similar . Substantial reduction in Neck Disability Index scores occurred in both groups compared with preoperative values . The greater improvement in the Neck Disability Index score in the Bryan disc cohort persisted through the four-year follow-up period ( p < 0.001 ) . The four-year overall success rates were 85.1 % and 72.5 % for the arthroplasty and fusion groups , respectively ( p = 0.004 ) . The improvement in the arm pain score was substantial for both groups and significantly greater in the Bryan disc cohort ( p = 0.028 ) , and the neck pain scores showed persistently greater improvement in the Bryan disc group at forty-eight months of follow-up ( p = 0.001 ) . Short Form-36 physical component score improvement remained greater among the Bryan disc cohort ( p = 0.007 ) . The mean range of motion for the Bryan disc was 8.08 ° and 8.48 ° at twenty-four and forty-eight months , respectively . Total and serious adverse event rates were similar between the groups . CONCLUSIONS The forty-eight-month follow-up data in the present report showed consistent , sustained significantly superior outcomes for cervical spine arthroplasty compared with cervical spine 
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Conclusions The available evidence showed that most of the pre-selected factors had no effect on outcome after C-ADR , and the ROM success rate , incidence of HO and r-ASD/ASD , and surgery rate for ASD are acceptable .