Bryan Cervical Disc Arthroplasty Research Articles

20-year Clinical Outcomes of Cervical Disc Arthroplasty: A Prospective, Randomized, Controlled Trial.

Prospective, Randomized, Controlled Trial. To compare clinical outcomes of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) at 20 years. Concern for adjacent level disease after ACDF prompted development of CDA. 47 patients with single level cervical radiculopathy were randomized to either BRYAN CDA or ACDF for an FDA IDE trial. At 20 years, patient reported outcomes, including visual analog scales (VAS) for neck and arm pain, neck disability index (NDI), and reoperation rates were analyzed. Follow-up rate was 91.3%. Both groups showed significantly better NDI, VAS arm pain and VAS neck pain scores at 20 years versus preoperative scores. Comparing CDA versus ACDF, there was no difference at 20 years in mean scores for NDI [11.1 (SD 14.1) vs. 19.9 (SD 17.2), P=0.087], mean VAS arm pain [0.9 (SD 2.4) vs. 2.3 (SD 2.8), P=0.095], or mean VAS neck pain [1.2 (SD 2.5) vs. 2.9 (3.3), P=0.073]. There was a significant difference between CDA versus ACDF groups in the change in VAS neck pain score between 10 and 20 years [respectively, -0.4 (SD 2.5) vs. 1.5 (SD 2.5), P=0.030]. Reoperations were reported in 41.7% of ACDF patients and 10.0% of CDA patients (P=0.039). Both CDA and ACDF are effective in treating cervical radiculopathy with sustained improvement in NDI, VAS neck and VAS arm pain at 20 years. CDA demonstrates lower reoperation rates than ACDF. There were no failures of the arthroplasty device requiring reoperation at the index level. Symptomatic non-union rate of ACDF was 4.2% at 20 years. Despite a higher reoperation rate in the CDA group versus ACDF group, there was no difference in the 20-year NDI, VAS Neck and VAS arm pain scores.

Influence of the deviated center of rotation on the range of motion after cervical disc arthroplasty –an in vivo study with a minimum of 10-year follow-up

BackgroundShort-term researches have studied the change of the center of rotation (COR) after the Bryan Cervical disc arthroplasty (CDA). But there is a lack of long-term studies focusing on the location of COR and its influence after surgery.MethodsClinical and radiographic materials of patients who received CDA were retrospectively reviewed. Written informed consents were obtained. Clinical outcome was accessed by Japanese Orthopaedic Association (JOA), Neck Disability Index (NDI), and Odom’s scale. Radiographic evaluation underwent before surgery, at early (3 months) follow-up and final (minimal 10 years) follow-up. The ROM of the global cervical spine and index level, the functional spine unit (FSU) angle and C2-C7 angle were measured. COR was identified and its coordinates were calculated. The absolute change of COR-x and COR-y were compared in subgroup analysis.ResultsSixty patients were included, with an average age of 55.9 ± 8.1 years old. The mean duration of follow up was 135.1 ± 16.1 (120–155) months. JOA, NDI and Odom’s scale showed significant improvements at 10 years after surgery. The COR of index level was located in the posterior superior half of the caudal vertebral body. Following the implant of Bryan Disc, the COR shifted forward and downward. During the 10-year follow-up, the location of COR remained stable. ROM at the index level decreased from 10.6 ± 4.0° preoperatively to 9.3 ± 4.0° at the early follow-up (p = 0.03). The ROM at the index level remained unchanged from early follow-up to the final follow-up (9.3 ± 4.0° vs 9.5 ± 5.2°, p = 0.80). In subgroup analysis, larger changes of both COR-x and COR-y were related with decreased ROM.ConclusionsOur study illustrated that Bryan CDA could achieved favorable clinical and radiographic outcome over a minimal 10-year follow-up. The reduction of the flexion-extension ROM may be correlated with a more deviated postoperative COR. More attention should be paid to preoperative design and intraoperative technique to obtain a more native COR.

What's New in Spine Surgery.

What's New in Spine Surgery.

Effect of heterotopic ossification after bryan-cervical disc arthroplasty on adjacent level range of motion: A finite element study

BackgroundQuantitative bone re-modelling theories suggest that bones adapt to mechanical loading conditions. Follow-up studies have shown that total disc replacement (TDR) modifies stress patterns in the bones, leading to heterotopic ossification (HO). Although there are a few studies on HO using finite element models (FEM), its effect on the adjacent levels and change in range of motion (ROM) have not been adequately investigated. This study interfaces the HO using bone re-modelling algorithm with a finite element solution and investigates the subsequent changes in segmental ROM. MethodsA FEM of the human cervical spine (C3–C7) was developed for this study, with material properties obtained from literature. The motion of the segments in the sagittal, frontal and transverse planes under combined loading conditions of 1 Nm moment and 73.6 N compression were validated against experimental corridors. The natural disc between the C5–C6 segment was replaced with the Bryan artificial cervical disc, and changes in sagittal ROM were compared before and after HO. The process of HO was simulated using a bone remodelling algorithm using strain energy density (SED) as the mechanical stimuli. Results and conclusionOur study demonstrates the feasibility of using SED calculations from the flexion-extension loading conditions for prediction of HO after ADR. The current findings suggest that the nature of trabecular stresses, and the subsequent rate and location of HO formation could differ based on the geometric design and nature of constraint for different artificial discs. The Bryan disc significantly reduced ROM at the implanted level in flexion. However, in extension, ROM increased at the implanted level and decreased slightly at the adjacent levels. After HO, ROM drastically reduced at the implanted level in both extension and flexion, and showed a minor increase in the adjacent levels, indicating that biomechanical behavior of high-grade HO is similar to a fused segment, thereby reducing the intended and initial motion preservation.

Single-level Bryan cervical disc arthroplasty: evaluation of radiological and clinical outcomes after 18years of follow-up.

Many studies reported mid-term clinical and radiological outcomes after cervical disc arthroplasty. Only a few studies analysed the long-term results. The aim of the study was to evaluate the clinical and radiological outcomes in patients treated with single-level Bryan cervical disc arthroplasty after 18years of follow-up. This study was a retrospective analysis of institutional databases concerning patients treated with Bryan cervical disc arthroplasty. SF36 PCS, NDI and VAS were used to evaluate clinical and functional outcomes. Standard, flexion-extension X-ray and MRI were used to evaluate the radiological results. Fifty-seven patients treated with single-level Bryan cervical disc arthroplasty completed the 18-year follow-up. At the final follow-up, a residual movement was observed in 32 patients (56%). The treated level range of motion decreased from 10.1° pre-operatively to 6.1° at the last follow-up (p = 0.0021). The range of motion of the adjacent segments and of the cervical spine had no significant change. Disc degeneration of the adjacent segment after 18-year follow-up was observed in 77.1% of treated patients. The clinical and radiographic outcomes 18years after surgery are acceptable. The treated level range of motion reduction and the adjacent segment degeneration seems not to affect the clinical results after 18years of follow-up.

Employment Status for the First Decade Following Randomization to Cervical Disc Arthroplasty Versus Fusion.

An analysis of employment status data up to 10 years following the Federal Drug Administration (FDA) Investigational Device Exemption (IDE) randomized trial and extension as post-approval study comparing BRYAN cervical disc (Medtronic, Minneapolis, MN) arthroplasty (CDA) versus single-level anterior cervical discectomy and fusion (ACDF) was performed. Ten-year experience with the BRYAN disc arthroplasty trial provides opportunity to report patient employment data. The long-term consequences of arthroplasty remain incomplete, including the occurrence of occupational compromise. Patients' employment status were measured at regular intervals in both groups up to 10 years. The preoperative employment status proportion was comparable between investigational (BRYAN CDA) and control (ACDF) groups. In the investigational group, 49.2% returned to work at 6 weeks compared with 39.4% of the control group (P = 0.046). At 6 months and 2 years postoperatively, there was a similar likelihood of active employment in both groups. After 2 years at all time points, 10% drop-off seen in control group employment, but not in investigational group. At 10 years, 76.2% CDA patients were employed to 64.1% ACDF patients (P = 0.057). Preoperative variables influencing work status at 10 years following CDA included: preoperative work status, age, and SF-36 Mental Component Score (SF-36 MCS); whereas, no significant preoperative factor identified with ACDF. Time to return to work was influenced in both groups by preoperative work status; and in the ACDF group: reaching age 65 at 10-year visit, preoperative arm pain and NDI score had significant influences. More patients returned to work at 6 weeks after CDA compared with ACDF, although there was no difference by 6 months. After 2 years, a nonsignificant trend toward higher employment rates in the arthroplasty group was evident, but this difference could not be validated due to the very high rate of loss of patients to the follow-up. 2.

Functional Outcomes Associated With Adjacent-level Ossification Disease 10 Years After Cervical Disc Arthroplasty or ACDF.

A retrospective review of a prospective, randomized control Food and Drug Administration (FDA) investigational device exemption trial comparing anterior cervical discectomy and fusion (ACDF) with Bryan cervical disc arthroplasty. Determine the clinical significance of adjacent-level ossification disease (ALOD) on long-term functional outcomes after ACDF or arthroplasty. ALOD occurs when the anterior longitudinal ligament and annulus adjacent to the index surgical level calcifies. As previously reported, ALOD happens more commonly after an arthrodesis than an arthroplasty. No investigation has previously examined 10-year clinical outcomes associated with ALOD. Forty patients were included in the 10-year follow-up. The index level was radiographically blinded and the cephalad-adjacent level was evaluated for ALOD. These scores underwent statistical analysis to compare the 2 surgical groups (ACDF and arthroplasty) for differences in the development of ALOD at a decade follow-up. Two investigational groups, on the basis of a high or low ALOD score, then proceeded through statistical analysis to compare the functional outcomes of patients in each group. Statistical evaluation of ALOD findings in patients from each surgical group found a significantly higher rate of high-grade ALOD in patients who underwent cervical arthrodesis with plate fixation compared with cervical arthroplasty (68.2% vs. 11.1%, P=0.0003). Functional outcomes of patients were also assessed at the 10-year mark and outcomes in patients with either high-grade or low-grade ALOD were compared. When stratified by high versus low-grade ALOD, no significant difference was found for Neck Disability Index (NDI) (P=0.6431), VAS-arm (P=0.4497), or VAS-neck (P=0.8700) scores between groups. The present study suggests that there are no significant long-term functional outcome differences between patients with and without significant ALOD. Our findings suggest ALOD may be a radiographic finding that does not alter patient-reported outcomes. Level III-therapeutic.

117. Ten-year BRYAN cervical disc arthroplasty: does change in angular motion have an effect on changes in patient-reported outcomes?

BACKGROUND CONTEXT Cervical disc arthroplasty (CDA) has been advocated as an alternative to anterior cervical discectomy and fusion with the added potential benefit of maintaining angular motion. The BRYAN cervical disc has been studied with over 10 years of data currently reported. PURPOSE The purpose of the study was to report the correlation between change in range of motion (ROM) and change in patient-reported outcomes. STUDY DESIGN/SETTING This was a prospective, randomized multicenter Investigational Device Exemption (IDE) trial with surgeries performed between May 2002 and October 2004. A 10-year analyses of patient-reported outcomes, using BRYAN cervical disc arthroplasty at a single level, was performed. PATIENT SAMPLE A total of 242 patients received BRYAN CDA (110=male, and 132=female). OUTCOME MEASURES Using Neck Disability Index (NDI), neck pain and arm pain scores and ROM to determine the correlation between change in ROM and change in patient-reported clinical outcomes. METHODS Eligible patients were ≥21 years of age with symptomatic cervical disc disease who had failed conservative care for at least 6 weeks. We documented patients' preoperative and postoperative follow-ups completed at regular intervals; clinical outcomes (NDI, neck pain and arm pain); and ROM were used for analysis. A correlation analysis was done, between change in ROM from preoperative to postoperative (regular follow-ups) and change in clinical outcomes from preoperative to postoperative. The analysis was performed using the Pearson correlation coefficient. RESULTS A total of 242 patients received BRYAN CDA (110=male, and 132=female) with a mean age of 44.4 years. There was no significant difference in the mean of ROM from preoperative (6.54°) to 3-month postoperative (6.3°). However, the mean change of ROM, from preoperative to all visits after 3 months, was statistically significant throughout the follow-up at 10 years with the mean change of ROM at the 10-year follow-up being 2.1° and the mean of ROM being 8.69°. NDI, neck pain and arm pain scores improved significantly by 38.3, 54.3 and 58.1 (p CONCLUSIONS The ROM did not change significantly; however, NDI, neck and arm pain scores improved significantly after 3 months postoperatively. ROM was maintained and clinical outcomes were further improved in the follow-ups. The change in range of motion had no effect on change in clinical outcomes. With 10 years of data, there was no meaningful correlation between change in range of motion and change in patient reported clinical outcomes with BRYAN cervical disc arthroplasty. FDA DEVICE/DRUG STATUS BRYAN cervical disc (Approved for this indication).

Wednesday, September 26, 2018 3:35 PM – 5:05 PM Preserving Spinal Motion: 84. Ten-year adverse events after randomization to BRYAN cervical disc arthroplasty versus anterior cervical discectomy and fusion

BACKGROUND CONTEXT Cervical disc arthroplasty (CDA) has been advocated as an alternative to anterior cervical discectomy and fusion (ACDF) with the added potential benefit of an early return toward unrestricted activities. However, the long-term adverse of arthroplasty are yet to be fully reported. A 10-year experience with the BRYAN disc arthroplasty trial provides the opportunity to report adverse events. PURPOSE To investigate the adverse rates between BRYAN CDA and ACDF. STUDY DESIGN/SETTING Prospective, randomized multicenter IDE trial with surgeries performed between May 2002 and October 2004. PATIENT SAMPLE A total of 242 patients received BRYAN CDA (110=male, and 132=female) with a mean age 44.4 years; 221 patients received ACDF (113=male, and 108=female) with a mean age of 44.7 years. OUTCOME MEASURES Adverse that occurred up to 10 years after the initial surgery. METHODS A 10-year analysis of outcomes following FDA investigation of patients randomized to the BRYAN cervical disc arthroplasty versus fusion at a single level was performed. Patients were followed at regular intervals and adverse associated with CDA and ACDF were recorded. Adverse included: cancer, cardiovascular, carpal tunnel syndrome, death, dysphagia or dysphonia, gastrointestinal, infection, urogenital, respiratory, implant displacement/loosening, implant malposition, neck and arm pain, neurological, non-union, spinal events, other events, other pain and intraoperative vascular injury. Other events consisted of various that did not fit into another category, such as rash, depression, or hypertension. Each adverse event was compared between groups for the cumulative rate up to 10 years. Time to event analysis with a log-rank test was used for analysis. RESULTS At up to 10 years of follow-up, 231 patients in the CDA group (cumulative rate 98.4%) and 199 patients in the ACDF group (cumulative rate 98.7%) had at least one adverse event (p=0.166). The cumulative rates of the following adverse were not different between the two groups for cancer (p=.860), cardiovascular (p=.653), death (p=.507), dysphonia/dysphagia (p=.341), gastrointestinal (p=.389), infection (p=.669), urogenital (p=.873), respiratory (p=.984), implant displacement/loosening (p=.200), implant malposition (p=0.179), neck and arm pain (p=.411), neurological (p=.888), other pain (p=.147), spinal (p=.792), urogenital (p=0.873) and intraoperative vascular injury (p=.583). However, the cumulative rates were different between the CDA and ACDF groups for non-union (p=.019), other (p=0.015) and trauma (p=0.012). CONCLUSIONS The cumulative rates of patients who had any adverse were not different between BRYAN artificial cervical disc and the anterior cervical arthrodesis group. In addition, the cumulative rates were not different between the two groups for the majority of categories as well. FDA DEVICE/DRUG STATUS BRYAN cervical disc (Approved for this indication).

Clinical and radiological outcomes of cervical disc arthroplasty: tenyear follow-up study.

Previous studies have demonstrated that cervical disc arthroplasty has favourable short- and medium-term clinical and radiological outcomes. However, long-term follow-up outcomes have rarely been reported. The purpose of this study was to evaluate the tenyear follow-up clinical and radiological outcomes in patients who underwent Bryan cervical disc arthroplasty. Seventy-one patients who underwent single-level Bryan cervical disc arthroplasty with a minimum tenyear follow-up were included in the study. Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and Odom's criteria were used to evaluate clinical outcomes. X-ray, CT, and MRI were used to evaluate the radiological outcomes. At last follow-up, the JOA score and NDI improved significantly, and 65 patients (91.5%) had good or excellent outcomes according to Odom's criteria. The range of motion (ROM) at operated level was 9.7° pre-operatively and maintained to 8.6° at last follow-up. The sagittal alignment of operated level was decreased from 2.1° pre-operatively to 1.2° at last follow-up (P < 0.01). The ROM and sagittal alignment of cervical spine had no significant change. At last follow-up, 16 patients (22.5%) developed segmental kyphosis, and 33 patients (46.5%) developed adjacent segment degeneration. Paravertebral ossification (PO) was observed in 66 patients (93.0%), and high-grade PO (grades III and IV) was observed in 25 patients (35.2%). The clinical and radiological outcomes of Bryan cervical disc arthroplasty over tenyears follow-up are satisfying. However, the occurrence of high-grade PO restricted the ROM of operated level.

1 - Ten-Year Outcomes from a Prospective Randomized Trial Comparing Bryan Cervical Disc Arthroplasty with Anterior Cervical Decompression and Fusion

1 - Ten-Year Outcomes from a Prospective Randomized Trial Comparing Bryan Cervical Disc Arthroplasty with Anterior Cervical Decompression and Fusion

Impact of T1 slope on surgical and adjacent segment degeneration after Bryan cervical disc arthroplasty.

BackgroundThis retrospective study investigated an association between preoperative T1 slope and surgical and adjacent segment degeneration (SASD) after Bryan cervical disc arthroplasty (BCDA) in patients with cervical degenerative disc disease.MethodsBased on preoperative standing lateral radiographs, 90 patients were classified according to T1 slope that was higher or lower than the 50th percentile (high T1 or low T1, 28 and 62 patients, respectively). Patients were also classified as SASD or non-SASD (38 and 52 patients, respectively) determined by radiographs at final follow-up. Visual analog scale (VAS) and Neck Disability Index (NDI) scores for neck and arm pain were noted, and changes in the sagittal alignment of the cervical spine (SACS), functional spinal unit (FSU) angle, and FSU range of motion (ROM) were also noted. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for SASD.ResultsThe overall rate of SASD was 42.2% (38/90). The SACS, FSU angle, FSU ROM, and SASD rates of the high T1 and low T1 slope groups were significantly different at the last follow-up. The NDI and VAS scores of the high T1 slope group were significantly greater than those of the low T1 slope. The multivariate logistic regression analysis showed that high T1 slope and endplate coverage discrepancy (ie, residual space behind the prosthesis) were significant risk factors for SASD after BCDA.ConclusionHigh T1 slope and endplate coverage discrepancy were associated with SASD after BCDA. Patients with a high preoperative T1 slope have a smaller FSU angle and more neck pain after BCDA.

Anterior Migration After Bryan Cervical Disc Arthroplasty: The Relationship Between Hyperlordosis and its Impact on Clinical Outcomes.

Various modifications have been tested to prevent kyphosis after Bryan cervical disc arthroplasty (CDA). However, the migration of Bryan prostheses has not been systematically studied. This study investigated the cause of anterior migration (AM) and assessed the effect of AM on clinical and radiographic outcomes. We retrospectively reviewed 46 consecutive patients who underwent modified Bryan CDA between August 2006 and December 2010. We measured functional spinal unit, angle of operative disc space, range of motion, and sagittal alignment of cervical spine preoperatively, postoperatively, and at the final follow-up, and compared these values between the AM and non-AM groups. Clinical outcome was evaluated by scores for Japanese Orthopaedic Association, Neck Disability Index, and visual analog scale. AM occurred in 9/46 (19.6%) patients. Clinical outcomes in both groups were significantly improved compared with the preoperative scores (P < 0.05). However, the postoperative and final follow-up angle of operative disc space was more lordotic and the postoperative functional spinal unit significantly higher in patients in the AM group compared with the non-AM group (P < 0.05). At the final follow-up, patients with AM had significantly higher Neck Disability Index and neck visual analog scale scores (P < 0.05), partially restricted range of motion (4.9° vs. 7.4°; P < 0.05), and adjacent segment degeneration at 6 vertebral levels (46.2%). The intermediate clinical outcomes for patients treated with modified Bryan CDA were satisfactory; however, overcorrection of segmental lordosis may lead to AM of the prosthesis, which could restrict patient range of motion and cause postoperative neck pain.

Application of Cervical Arthroplasty With Bryan Cervical Disc: 10-Year Follow-up Results in China.

Retrospective study. The aims of this study were to evaluate the radiographic and clinical outcomes of Bryan cervical disc arthroplasty at 10-year follow-up. Cervical arthroplasty is a new technique for treating degenerative cervical disease. Previous reports have shown that cervical arthroplasty with Bryan disc gained good clinical outcomes at 4- to 6-year follow-up. Clinical outcomes and dynamic x-ray examination were evaluated at baseline and at final follow-up. Thirty-three patients with complete clinical and radiographic data were included in this study. The mean follow-up period was 120.5 months (116-130 months). Twenty-five patients underwent single-level arthroplasty and 7 underwent arthroplasty at 2 levels. One patient underwent arthroplasty at 3 levels. Eight of the 33 patients presented with radiculopathy and 25 patients with myelopathy. The 42 levels of surgery included C3/4 (3 levels), C4/5 (7 levels), C5/6 (26 levels) and C6/7 (6 level). The mJOA score of the 25 patients with myelopathy was 11.8 at the baseline and 15.9 at the final follow-up. No patient suffered from adjacent segment disease. Two patients received revision surgeries at the index level for recurrent radiculopathy caused by osteophyte formation and heterotopic ossification. On x-ray examination, the range of motion at the operated level was 7.8 degree at the baseline and 4.7 degree at the final follow-up. Heterotopic ossification was observed in 29 (69.0%) levels and heterotopic ossification of Grade 4 was observed in 14 levels. Adjacent segment degeneration was observed in 30 (47.6%) levels. Cervical arthroplasty using Bryan cervical disc prosthesis resulted in fine clinical outcomes in this study. Heterotopic ossification was common after Bryan disc arthroplasty, which decreased the range of motion. 4.

Clinical and Radiological Results of Bryan Cervical Disc Arthroplasty after Follow-Up of Ten Years

Clinical and Radiological Results of Bryan Cervical Disc Arthroplasty after Follow-Up of Ten Years

Implant migration after Bryan cervical disc arthroplasty

Implant migration after Bryan cervical disc arthroplasty

Randomized, Controlled, Multicenter, Clinical Trial Comparing BRYAN Cervical Disc Arthroplasty With Anterior Cervical Decompression and Fusion in China

Prospective, randomized, controlled, multicenter clinical trial. To compare outcomes of cervical disc arthroplasty with those of anterior cervical decompression and fusion (ACDF) in a Chinese population. Cervical disc arthroplasty has been found to be superior to ACDF for maintaining range of motion (ROM) at the index spinal segment and possibly will avoid abnormal stress to adjacent segments. A total of 120 patients from 3 large hospitals in China were randomly assigned to treatment with cervical disc arthroplasty (n = 60) using the BRYAN prosthesis or ACDF (n = 60) and were observed postoperatively for 24 months. The 2 groups had similar preoperative demographics and baseline characteristics including ROM, neck disability index, and visual analogue scale for neck and arm pain. The total disc replacement (TDR) group had a significantly longer operation time than the ACDF group (P < 0.001). Outcome data obtained after 24 months revealed a significant difference between the groups in mean change from baseline in ROM at the index level (P < 0.001); ROM was maintained in the TDR group but reduced in the ACDF group. There were no significant between-group differences in the baseline changes in neck disability index or visual analogue scale scores for pain. One patient in the TDR group and 4 patients in the ACDF group required reoperations. At 24 months after surgery, the cervical disc prosthesis yielded good clinical results while maintaining ROM at the index level. Cervical disc arthroplasty appears to be a viable alternative to ACDF.

Results of Cervical Arthroplasty Compared with Anterior Discectomy and Fusion: Four-Year Clinical Outcomes in a Prospective, Randomized Controlled Trial

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. A prospective, multicenter randomized clinical trial was undertaken for the treatment of persistent radiculopathy or myelopathy due to single-level cervical disc herniations or spondylosis. Patients were randomized 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. 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. 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 fusion. The arthroplasty cohort continued to show significantly greater improvements in Neck Disability Index, neck pain score, arm pain score, and Short Form-36 physical component score, as well as the primary outcome measure, overall success, at forty-eight months following surgery.

Clinical and radiological outcomes of modified techniques in Bryan cervical disc arthroplasty

Kyphosis may occur after arthroplasty as the result of the disc insertion angle and overmilling; however, few studies have described techniques to avoid these factors. We investigated whether modified techniques of Bryan cervical disc arthroplasty can prevent adverse outcomes. Twenty patients (control group) underwent surgery using techniques described in the Bryan disc product monograph (Medtronic Sofamor Danek, Minneapolis, MN, USA). Twenty-nine patients (investigation group) underwent surgery using a modified technique which included changes in disc insertion angle, reducing overmilling of the endplates, ensuring the anterior borders of the two halves of the prosthesis were at the same horizontal line, and accurately fitting the prosthesis. Disability and pain were assessed using self-administered questionnaires and the change in functional spinal unit (FSU) angle between the two groups was also compared. Both groups demonstrated statistically significant improvement compared with preoperative values for the following functional outcomes measures. The mean neck pain Visual Analog Scale (VAS) scores before surgery were 73.45 (control) and 74.53 (investigation); at the 2-year follow-up these scores were 22.1 and 14.79 ( p = 0.0013), respectively. After surgery, 14 of 20 patients in the control group developed a tendency toward kyphosis of the FSU in the neutral position (range = –9°–13°, mean = –1.1 °± 5.05). Conversely, none of the 29 patients in the investigation group developed kyphosis of the FSU in the neutral position (range = 0–10°, mean = 3.79° ± 2.90) ( p = 0.0007). There was no statistically significant difference between the groups regarding preoperative and postoperative scores with the exception of neck pain VAS and FSU angle changes. There were no intraoperative complications, vascular or neurologic complications, spontaneous fusions, or device failures or explantations.

Adjacent-Level Cervical Ossification After Bryan Cervical Disc Arthroplasty Compared with Anterior Cervical Discectomy and Fusion

Ossification of the anterior longitudinal ligament and the anulus adjacent to an anterior cervical arthrodesis has been termed adjacent-level ossification development. Initial studies suggested an association with the placement of plates <5 mm from an adjacent disc space. A follow-up study demonstrated that this ossification rarely occurs in association with arthrodeses without plate fixation. In the present study, our goal was to determine the incidence of adjacent-level ossification in patients who underwent cervical arthrodesis with plate fixation as compared with that in patients who underwent cervical arthroplasty. We performed a post hoc analysis of prospectively collected data. Radiographic data for all patients from a single site were used. All postoperative, two-year, and four-year follow-up lateral cervical spine radiographs were collected and formatted to occlude the surgical level, blinding the readers as to the procedure performed. Three independent blinded surgeons graded the cephalad adjacent level for the degree of ossification at each time point. The data were statistically analyzed for significant ossification grade differences between arthrodesis and arthroplasty. A total of forty-six patients (twenty-one with a Bryan total disc arthroplasty and twenty-five with an arthrodesis) were included. Both cohorts were derived from previous participation in a Level-I multicenter prospective randomized controlled trial stratified by site. Ossification scores based on independent assessment by three readers at multiple follow-up times were used. The arthrodesis group had significantly higher ossification scores than the arthroplasty group at both the two-year (p = 0.003) and the four-year follow-up interval (p = 0.004). Both cohorts showed significant increases in ossification from the two-year follow-up to the latest follow-up (p = 0.001 for the anterior cervical arthrodesis group and p = 0.008 for the arthroplasty group). Our data conclusively demonstrate that cervical intervertebral arthroplasty is associated with a significantly lower incidence of adjacent-level ossification than arthrodesis with plate fixation at both the two-year and the four-year follow-up. Arthroplasty has the advantage of not being associated with adjacent-level ossification, which may decrease cervical spine motion above and below the surgical level.