***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    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 Study Design . A prospect i ve , r and omized , multicenter , Food and Drug Administration-regulated Investigational Device Exemption clinical trial . Objective . To evaluate the safety and effectiveness of the ProDisc ® -L ( Synthes Spine , West Chester , PA ) lumbar total disc replacement compared to circumferential spinal fusion for the treatment of discogenic pain at 1 vertebral level between L3 and S1 . Summary of Background Data . As part of the Investigational Device Exemption clinical trial , favorable single center results of lumbar total disc replacement with the ProDisc ® -L have been reported previously . Methods . Two hundred eighty-six ( 286 ) patients were treated on protocol . Patients were evaluated before and after surgery , at 6 weeks , 3 , 6 , 12 , 18 , and 24 months . Evaluation at each visit included patient self- assessment s , physical and neurologic examinations , and radiographic evaluation . Results . Safety of ProDisc ® -L implantation was demonstrated with 0 % major complications . At 24 months , 91.8 % of investigational and 84.5 % of control patients reported improvement in the Oswestry Low Back Pain Disability Question naire ( Oswestry Disability Index [ ODI ] ) from preoperative levels , and 77.2 % of investigational and 64.8 % of control patients met the ≥15 % Oswestry Disability Index improvement criteria . Overall neurologic success in the investigational group was superior to the control group ( 91.2 % investigational and 81.4 % control ; P = 0.0341 ) . At 6 weeks and 3 months follow-up time points , the ProDisc ® -L patients recorded SF-36 Health Survey scores significantly higher than the control group ( P = 0.018 , P = 0.0036 , respectively ) . The visual analog scale pain assessment showed statistically significant improvement from preoperative levels regardless of treatment ( P < 0.0001 ) . Visual analog scale patient satisfaction at 24 months showed a statistically significant difference favoring investigational patients over the control group ( P = 0.015 ) . Radiographic range of motion was maintained within a normal functional range in 93.7 % of investigational patients and averaged 7.7 ° . Conclusions . ProDisc ® -L has been found to be safe and efficacious . In properly chosen patients , ProDisc ® -L has been shown to be superior to circumferential fusion by multiple clinical criteria OBJECT The authors report the results of a prospect i ve r and omized multicenter study in which the results of cervical disc arthroplasty were compared with anterior cervical discectomy and fusion ( ACDF ) in patients treated for symptomatic single-level cervical degenerative disc disease ( DDD ) . METHODS Five hundred forty-one patients with single-level cervical DDD and radiculopathy were enrolled at 32 sites and r and omly assigned to one of two treatment groups : 276 patients in the investigational group underwent anterior cervical discectomy and decompression and arthroplasty with the PRESTIGE ST Cervical Disc System ( Medtronic Sofamor Danek ) ;  265 patients in the control group underwent decompressive ACDF . Eighty percent of the arthroplasty-treated patients ( 223 of 276 ) and 75 % of the control patients ( 198 of 265 ) completed clinical and radiographic follow-up examinations at routine intervals for 2 years after surgery . Analysis of all currently available postoperative 12- and 24-month data indicated a two-point greater improvement in the neck disability index score in the investigational group than the control group . The arthroplasty group also had a statistically significant higher rate of neurological success ( p = 0.005 ) as well as a lower rate of secondary revision surgeries ( p = 0.0277 ) and supplemental fixation ( p = 0.0031 ) . The mean improvement in the 36-Item Short Form Health Survey Physical Component Summary scores was greater in the investigational group at 12 and 24 months , as was relief of neck pain . The patients in the investigational group returned to work 16 days sooner than those in the control group , and the rate of adjacent-segment reoperation was significantly lower in the investigational group as well ( p = 0.0492 , log-rank test ) . The cervical disc implant maintained segmental sagittal angular motion averaging more than 7 degrees . In the investigational group , there were no cases of implant failure or migration . CONCLUSIONS The PRESTIGE ST Cervical Disc System maintained physiological segmental motion at 24 months after implantation and was associated with improved neurological success , improved clinical outcomes , and a reduced rate of secondary surgeries compared with ACDF Study Design . Prospect i ve study analyzing midterm clinical results of  total lumbar disc replacement ( ProDisc II )  for different indications . Objectives . To assess functional outcome after total lumbar disc replacement ( TDR )  treated for varying indications . Summary of Background Data . Despite its frequent use and increasing popularity , indications and contraindications for TDR have not been defined precisely at this stage and remain a matter of debate , leading to disc replacement procedures in a variety of pathologies that have not yet been evaluated and compared separately . Methods . Patients meeting inclusion criteria were evaluated prospect ively according to Visual Analogue Scale ( VAS ) , Oswestry Question naire , SF-36 , and numerous clinical parameters . Indications included degenerative disc disease ( DDD ) , DDD with accompanying soft disc herniation ( nucleus pulposus prolapse , NPP ) , osteochondrosis following previous discectomy , and DDD with presence of Modic changes . Postoperative improvement was recorded and analyzed for influence of preoperative diagnosis . Results . Overall , 92 patients from four groups with a mean follow-up of 34.2 months ( minimum , 24 months ) achieved significant and maintained improvement from preoperative levels ( P < 0001 ) . Patients with DDD + NPP achieved results significantly better than patients from the other groups ( P < 0.05 ) . Presence of Modic changes or previous discectomy did not influence outcome negatively . Improvement was achieved for both monosegmental and bisegmental disc replacements ( P < 0.05 ) , nevertheless with significantly inferior results for bisegmental interventions at 12- and 24-month follow-up and considerably higher complication rate . While older patients were still highly satisfied with postoperative outcome , better functional outcome was observed in younger patients . Conclusion . Present data suggest beneficial clinical results of TDR for treatment of DDD in a highly selected group of patients . Better functional outcome was obtained in younger patients under 40 years of age and patients with degenerative disc disease in association with disc herniation . Multilevel disc replacement had significantly higher complication rate and inferior outcome . Results are significantly dependent on preoperative diagnosis and patient selection , number of replaced segments , and age of the patient at the time of operation . Because of significantly varying outcomes , indications for disc replacement must be defined precisely Abstract . Degenerative disc disease is one of the most frequently encountered spinal disorders . The intervertebral disc is a complex anatomic and functional structure , which makes the development of an efficient and reliable artificial disc a complex challenge . Not only is the disc function arduous to reproduce , but there are important consequences associated with the conception and the choice of material s that will have to bear the loads . Biochemical problems have complicated things even more . Two different principles have been applied in the realisation of a discal replacement : a metallic and /or polyethylene prosthesis allowing mainly mobility or a prosthesis enabling the reproduction of viscoelastic properties . Of course some devices attempt to combine both principles . In this paper we will try to present , in chronological order , an overview of the design s published in the literature as well as in the patents granted in this field . The very fact that such a long list of implants , based on highly varied principles , has been proposed , and that only very few have reached the level of animal models , let alone human implantation , clearly demonstrates how challenging the task of design ing an intervertebral disc replacement is . Proper r and omized controlled trials are now on the way , and should help in assessing the efficacy and real place of spine arthroplasty  in the treatment of spinal disorders . Only then will spinal surgery join the list of successful joint replacements SWISSspine is a so-called pragmatic trial for assessment of safety and efficiency of  total disc arthroplasty ( TDA ) .  It follows the new health technology assessment ( HTA ) principle of “ coverage with evidence development ” . It is the first m and atory HTA registry of its kind in the history of Swiss orthopaedic surgery . Its goal is the generation of evidence for a decision by the Swiss federal office of health about reimbursement of the concerned technologies and treatments by the basic health insurance of Switzerl and . During the time between March 2005 and 2008 , 427 interventions with implantation of 497 lumbar total disc arthroplasties have been documented . Data was collected in a prospect i ve , observational multicenter mode . The preliminary timeframe for the registry was 3 years and has already been extended . Data collection happens pre- and perioperatively , at the 3 months and 1-year follow-up and annually thereafter . Surgery , implant and follow-up case report forms are administered by spinal surgeons . Comorbidity question naires , NASS and EQ-5D forms are completed by the patients . Significant and clinical ly relevant reduction of low back pain VAS ( 70.3–29.4 points preop to 1-year postop , p < 0.0001 ) leg pain VAS ( 55.5–19.1 points preop to 1-year postop , p < 0.001 ) , improvement of quality of life ( EQ-5D , 0.32–0.73 points preop to 1-year postop , p < 0.001 ) and reduction of pain killer consumption was revealed at the 1-year follow-up . There were 14 ( 3.9 % ) complications and 7 ( 2.0 % ) revisions within the same hospitalization reported for monosegmental TDA ; there were 6 ( 8.6 % ) complications and 8 ( 11.4 % ) revisions for bisegmental surgery . There were 35 patients ( 9.8 % ) with complications during followup in monosegmental and 9 ( 12.9 % ) in bisegmental surgery and 11 ( 3.1 % ) revisions with new hospitalization in monosegmental and 1 
    Output:
    
The present systematic review attempts to give an overview of the current status of disc arthroplasty