cervical total disc replacement ( ctdr ) was first introduced in europe in the late 1990s . subsequently , three prospective , randomized food and drug administration ( fda ) regulated investigational device exemption ( ide ) trials were initiated in the us dating back to 2000 . these initial ide studies ultimately led to the first three fda approvals for ctdr devices in the us , prestige st ( medtronic- 541 patients , 32 sites ) ( 2007 ) , prodisc - c ( depuy synthes- 209 patients , 13 sites ) ( 2008 ) and bryan disc ( medtronic- 463 patients , 30 sites ) ( 2009 ) , for the treatment of 1-level cervical spondylosis from c3 - 7 . there have been an additional three fda approvals , secure - c ( globus medical- 380 patients , 18 sites ) , pcm ( nuvasive- 342 patients , 24 sites ) ( 2012 ) and mobi - c ( ldr- 1level : 260 patients , 24 sites ; 2 level : 339 patients ) ( 2013 ) . there has also been a new indication as mobi - c was also approved for treatment of two - level cervical spondylosis c3 - 7 . all the us fda ide trials compared ctdr devices to standard anterior discectomy and fusion ( acdf ) in prospective and randomized studies producing level 1 data . as with all industry - sponsored studies , bias , both investigator and patient related , is a concern . this concern was somewhat mitigated by the fact that these ide studies have cumulatively involved over 2,500 patients at over 100 study sites ( table 1 ) . furthermore , these studies utilized similar validated outcome measures including neck disability index ( ndi ) , visual analog scale ( vas ) and sf-36 . acdf is an established surgical procedure with a well - documented safety and efficacy dating back 60 years . cervical arthroplasty offers some theoretical advantages over acdf .. acdf results in loss of motion at the index level(s ) , placing increased stress on adjacent levels above and below the fusion . there is a documented incidence of clinically symptomatic adjacent - level disc disease following acdf ranging from 0.5 - 3% annually . hilibrand et al . reported a rate of symptomatic adjacent - level degeneration following acdf of 2.9% annually , although the rate of adjacent level re- operation was only 0.7% per year . similarly , robertson and associates reported a symptomatic adjacent - segment degenerative disc disease rate of 7% in the anterior fusion series . by preserving motion at the operated level , ctdr has the potential to positively affect the occurrence of adjacent segment degeneration . fda - approved ctdr devices with number of patients enrolled in pivotal ide study . in order to establish an evidence based rationale for ctdr as a viable therapeutic modality in the treatment of cervical radiculopathy they must show clinical efficacy and safety through the regulatory ide process and receive the appropriate regulatory approval . additionally , cervical arthroplasty must validate that the technique maintains segmental motion with concomitant decreased adjacent level stresses compared to acdf . furthermore , the results of multi - center controlled studies should be replicated at individual centers . intermediate term data should reaffirm safety and efficacy beyond the two year follow - up mandated by fda ide process . once accepted as reasonable treatment option , long - term data should be utilized to refine ideal indications for that procedure . the results of seven different prospective , randomized studies have been published in peer - reviewed literature . these studies , comparing ctdr to standard anterior cervical discectomy and fusion ( acdf ) , have shown positive results for ctdr leading to six different fda approvals . although the statistical design of these studies was  non - inferiority .  on numerous clinical end - points , artificial discs were found to be statistically superior to fusion . mummaneni and colleagues showed statistically significant higher neurological success for the prestige st artificial disc . heller et al and coric et al documented statistically significant greater overall composite success rates for bryan and kineflexc , respectively . davis and associates reported statistically superior overall success for 2-level surgery with mobi - c . murrey and associates reported statistically significant decrease in secondary surgeries following prodisc - c placement . vaccarro et al showed statistically superiority in favor of secure - c in terms of overall success , secondary surgery as well as patient satisfaction . phillips et al reported statistically significant lower ndi scores and dysphagia rates as well as higher patient satisfaction for pcm . the following ctdr devices showed greater composite overall success ( prestige st 79% vs 68% ; prodisc - c 72% vs 68% ; bryan 83% vs 73% ; kineflexc 85% vs 71% ; secure - c 84% vs 73% ; pcm 75% vs 65% ; mobi - c 1-level 74% vs 65% , 2-level 70% vs 37%)(table 2 ) . range of motion data from the ide studies confirm that cervical arthroplasty devices maintain segmental motion ( in degrees ) at the treated level : prestige st ( 7.7 ) , bryan ( 6.5 ) , prodisc - c ( 8.4 ) , kineflexc ( 9.8 ) , secure - c ( 9.7 ) , pcm ( 5.7 ) , mobi - c 1-level ( 10.8 ) and 2-level ( 10.1 , 8.3 ) ( table 3 ) . the results of these multi - center studies have been replicated with single center results . coric demonstrated statistically higher overall success rates from a single institution utilizing three different ctdr devices . jawahar also combined data from three separate ctdr devices and reported clinical equivalence between arthroplasty and fusion , but no change in adjacent level disease at two years . garrido reported long - term outcomes for the bryan disc from a single site which favored ctdr on ndi , vas and fewer additional surgeries . level 2 and 3 data from single sites outside the united states ( ous ) have also shown positive clinical results . goffin and kim reported safety and efficacy with 1- and 2-level cervical arthroplasty using the bryan disc . bertagnoli and beuurain also showed good results with prodisc - c and mobi - c , respectively , at two year follow - up . intermediate and long - term follow - up studies , ranging from 4- to10-years , have also been published . burkus and associates reported statistically higher rate of disability ( ndi ) improvement at 3- and 5-years for ctdr with prestige st . they also showed a statistically lower rate of index level surgery for ctdr at 5-years . similarly , delamarter et al reported a statistically higher rate of vas satisfaction at all time points out to 4-year follow - up for prodisc - c ctdr over acdf . they also reported a statistically lower rate of index level surgery for ctdr at four years . quan reported eight - year outcomes on the bryan disc using odom criteria and showed good / excellent results in 90% of patients . coric et al reported that in both ctdr and acdf groups , the mean ndi and vas scores improved significantly by 6 weeks and remained significantly improved from 4- to 8-year follow - up . there is considerably less literature examining the use of cervical arthroplasty for multi- level cervical spondylosis . several studies have reported positive results for ctdr in patients with 2-level disease . as previously discussed , davis et al reported level 1 data from the prospective , randomized ide study comparing 2-level ctdr with mobi- c compared to 2-level acdf . these authors reported dramatically improved overall success with arthroplasty ( 70% versus 37% ) over fusion . bartels et al published a meta - analysis of six peer - reviewed articles and three meeting abstracts . these authors reported statistically superior results for ctdr in pain ( vas ) and function ( sf-36 ) at 12 months and disability ( ndi ) at 24 months , yet concluded that there was no proven clinical benefit for arthroplasty . mcafee and associates combined the results of four separate ide studies and reported statistical superiority for overall success , neurologic success and survivorship success for ctdr . upadhyaya and co - authors combined the completed data sets from the first 3 fda - approved ctdr devices and reported statistically significantly lower reoperation rate for adjacent level disease as well as superior neurological success . it is well understood that fusion sacrifices motion at the index level and places stresses on adjacent levels . adjacent level disease is likely a multifactorial process involving several disparate factors including natural history of the underlying disease process ( spondylosis ) , surgical technique , patient selection and type of instrumentation employed . it is also well established that arthroplasty maintains motion decreases adjacent level stress compared to fusion . it is important to differentiate between adjacent level degeneration ( deterioration above or below the operative level evident on radiographic imaging ) and adjacent level disease ( clinically symptoms attributable to a level above or below the operative level ) . the only level 1 studies to document statistically significant decrease in adjacent level disease for cervical arthroplasty are the previously discussed meta - analysis papers by mcafee and upadhyaya . a decreased rate of adjacent deterioration from the ide studies in favor of arthroplasty devices was reported by coric ( 9% vs 25% ) , davis(11% vs 23% ) and vaccarro . kim and associates also reported decreased degenerative change in patients treated with the bryan artificial disc . there are several unique complications associated with ctdr devices including subsidence / dislocation , wear debris / osteolysis and heterotopic ossification . the published results of ide studies generally show low rates of reoperation with the majority of these related to persistent neck pain without device failure . the rate of bridging heterotopic bone across these studies was also low , ranging from 0 - 3% . the safety and efficacy of cervical arthroplasty has been established with a growing body of level 1 evidence that is compelling enough to no longer consider ctdr investigational . this evidence is bolstered by experience with multiple devices , at multiple sites , in and out of the investigational setting and with short- , intermediate- and long - term follow - up . ctdr is a viable alternative to acdf in select patients with symptomatic 1- and 2-level cervical radiculopathy or myelopathy ( table 4 ) . clinically symptomatic cervical radiculopathy and/or myelopathy due to neural compression c3-c7 at one - level or two contiguous levels failed at least 6 weeks of nonsurgical treatment or shows signs of progressively clinical deterioration intractable radiculopathy ( arm pain and/or a neurological deficit ) with or without associated neck pain myelopathy ( due to abnormality localized to the level of the disc space ) dr . coric is a consultant to pioneer surgical , medtronic , globus medical , spine motion , & spine wave .
morgan lorio , md , facs , chair , isass task force on coding & reimbursementthe isass task force reached out to domagoj coric , md to provide a timely summation on cervical disc arthroplasty given his special interest and recent iasp championship of this innovative technology to insure enhanced spine patient access . 
 the isass task force is pleased with this step towards published isass societal policy and applauds dr . 
 coric 's effort ; if isass is to continue to succeed we must continually harness the voluntary talents and energies of our members with gratitude .