Bryan Artificial Cervical Disc Research Articles

Mid-long-term follow-up of operated level kinematics after single-level artificial cervical disc replacement with Bryan disc

ObjectiveEvaluation of the mid-long-term kinematics of single-level Bryan artificial cervical disc replacement (ACDR) in vivo by analyzing the center of rotation (COR) at the operated level.MethodsA retrospective analysis was conducted using data collected from 38 patients who underwent single-level Bryan ACDR from January 2010 to March 2013. Radiological parameters including range of motion (ROM), lordosis angle, translation, and COR were obtained. Clinical outcomes were assessed based on Odom Criteria, modified Japanese Orthopedic Association (mJOA), Neck Disability Index (NDI), and Visual Analogue Scale (VAS) scores. Correlations between COR and other follow-up data were discussed at the last follow-up.ResultsCompared with preoperative values, the last follow-up data showed that 86.84% of cases achieved good-or-excellent outcomes based on Odom criteria; Significant improvements were observed across all scales assessed for clinical outcomes (P < 0.05); Lordosis angle was significantly increased in both the overall cervical spine and the operated level (P < 0.05); ROM of the overall cervical spine, operated level, and adjacent levels was preserved (P > 0.05); There was no significant change in COR at the operated level (P > 0.05). At the last follow-up and at the operated level, COR (Y) showed negative correlations with ROM and translation (P < 0.05), but no follow-up data correlated with COR (X) were found (P > 0.05).ConclusionsSatisfactory clinical and radiological outcomes were achieved 7 years or more after single-level Bryan ACDR. At the operated level, preoperative COR was maintained, probably due to replicating the physiological interrelations of COR (Y), translation, and ROM.

Long-term outcomes of Bryan artificial cervical disc replacement for degenerative cervical spondylosis

Objective: To compare the long-term clinical effect and imaging results of Bryan artificial cervical disc replacement (ACDR) and anterior cervical discectomy and fusion (ACDF) and to explore whether ACDR can reduce the occurrence of postoperative adjacent segment degeneration (ASD) in the treatment of degenerative cervical spondylosis. Methods: It was a retrospective study. Total of 60 patients with degenerative cervical spondylosis, who had received operations by Bryan ACDR (n=27) and ACDF (n=33) in the Third Hospital of Hebei Medical University between January 2005 and December 2009 were enrolled in this study. The Japanese Orthopedic Association (JOA) scores, neck disability index (NDI), visual analogue scale (VAS), Odom's scale, cervical range of motion (ROM), surgical segment ROM, heterotopic ossification (HO) and ASD were used to evaluate the clinical and radiologic results. The indices abovementioned were compared between the two groups. Results: The VAS, NDI and JOA scores at each follow-up node in both ACDR and ACDF group were all significantly improved when compared with those before operation (all P<0.05), but there was no significant differences between the two groups (all P>0.05). Of all, 88.9%(24/27) of patients in ACDR group and 84.8%(28/33) of patients in ACDF group achieved excellent or good results, however, there was no significant difference in Odom's scale between the two groups (P>0.05). At the last follow-up, the cervical ROM in ACDR group was 43.2°±8.8°, which was slightly lower than that before operation (45.7°±10.4°), the difference was not statistically significant (t=0.954, P=0.345); the surgical segment ROM in ACDR group was 5.9°±3.6°, which was significantly reduced when compared with that before operation (8.8°±3.4°, t=3.043, P<0.01). However at the last follow-up, the cervical ROM in ACDF group was 36.4°±8.4°, which was significantly reduced when compared with that before operation (43.9°±11.1°), the difference was statistically significant (t=3.095, P<0.01). Although, there was no significant difference in the cervical ROM between the two groups before operation (t=0.643, P=0.523), and the difference was statistically significant at the last follow-up (t=3.054, P<0.01). At the last follow-up, the incidence of HO in ACDR group was 92.6%, and the high-grade HO was 37.0%. The incidence of ASD in ACDR group was 39.5%, which was much lower than that in ACDF group (61.1%, χ(2)=4.462, P=0.035). Conclusion: At minimum follow-up of 10 years, Bryan ACDR achieves a satisfactory clinical effect consistent with ACDF. In terms of advantages, ACDR could maintain the ROM of cervical and retain the ROM of the surgical segment, which reduces the occurrence of ASD by preserving motion.

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.

Long-term outcomes of cervical artificial disc replacement for patients with degenerative cervical canal stenosis

Objective To evaluate the long-term efficacy of cervical artificial disc replacement for patients with degenerative cervical canal stenosis. Methods All of 43 patients underwent single level Bryan cervical artificial disc replacement for degenerative cervical canal stenosis were retrospectively analyzed with a minimum 10 years follow-up in our hospital between December 2003 and December 2007. There were 28 males and 15 females with an average age of 56.7±8.0 years which ranged from 37 to 76 including 1 case of C3,4 level, 11 cases of C4,5 level, 26 cases of C5,6 level and 5 cases of C6,7 level. According to the symptoms and location of compression on radiograph, the patients were divided into 3 groups: 15 patients in radiculopathy group, 10 patients in myelopathy group and 18 patients in myeloradiculopathy group. Radiological evaluation indexes include global range of motion (ROM), segmental ROM, segmental Cobb angle. Clinical evaluation indexes including Japanese Orthopaedic Association (JOA) score, neck disability index (NDI) and Odom's criteria. The variable data were analyzed by one-way ANOVA, the grading data were analyzed by Kruskal-Wallis H test. The preoperative and postoperative data were analyzed by paired t test. Results At the last follow-up, the Cobb angle of the operative segment was 1.29°±1.34°in myelopathy group(t=4.606, P=0.001), 0.71°±2.20°in radiculopathy group (t=2.355, P=0.034), and 0.69°±2.12° in myeloradiculopathy group (t=3.312, P=0.004), which was significantly lower than that before operation. At the last follow-up, ROM of the operative segment in myelopathy group was 6.41°±4.87°, which was significantly lower than that before operation (11.46°±5.19°, t=3.589, P< 0.05), and there was no significant difference in the other two groups. There was no significant difference in other imaging parameters among the three groups. JOA scores at the last follow-up were 16.33±0.75 in radiculopathy group (t=5.857, P< 0.001), 16.00±1.05 in myelopathy group(t=8.337, P< 0.001) and 14.78±1.69 in radiculopathy group (t=4.045, P< 0.001); NDI were 13.07%±5.90% in radiculopathy group (t=7.097, P< 0.001), 12.60%±4.22% in myelopathy group (t=7.319, P< 0.001) and 23.11%±14.18% in radiculopathy group (t=4.229, P< 0.001), which were all significantly improved than those before operation. The excellent and good rate of Odom's criteria (H=2.719, 2.411, P< 0.05), JOA (LAD-t=3.770, 4.080, P<0.05) and NDI(LAD-t=2.850, 2.643, P< 0.05) at the last follow-up of the patients in radiculopathy group and myelopathy group were better than those of patients in myeloradiculopathy group (P< 0.05). Conclusion Cervical artificial disc replacement has a satisfied long-term clinical efficacy with degenerative cervical canal stenosis. The efficacy of myelopathy and radiculopathy were better than myeloradiculopathy. Key words: Cervical vertebrae; Spinal stenosis; Total disc replacement; Follow-up studies

Effect of Bryan cervical disc replacement on cervical curvature and replacement segment in treating cervical spondylosis

To investigate the effect of Bryan cervical disc replacement on cervical curvature and replacement segment in the treatment of cervical spondylosis, and analyze its clinical efficacy. Forty-nine patients underwent Bryan artificial cervical disc replacement from August 2010 to August 2013 were retrospectively analyzed. There were 26 males and 23 females, aged from 27 to 66 years old with an average of 48.5 years. Including 21 cases of nerve root type, 16 cases of spinal cord type, 12 cases of mixed type. And 21 cases were single segment replacement, 28 cases were double segments replacement. Preoperative and postoperative pain was compared using visual analogue scale(VAS);cervical function was observed by Japanese Orthopedic Association Scores (JOA) and Neck Disability Index (NDI);cervical lordosis curvature, function spinal unit(FSU) curvature, activities of replacement and adjacent segment, FSU activity were measured by cervical X-rays. Clinical effects were evaluated by the Odom method. All the patients were followed up for 18.5 to 37.3 months with an average of 33.1 months. Pvoperative VAS, JOA, NDI scores were 7.08±1.55, 5.2±1.9, 39.96±7.06 before operation, 3.76±2.33, 13.20±1.20, 25.20±6.64 at 3 months after operation, and 2.80±1.50, 14.3±1.6, 24.24±7.89 at the last follow-up. Patients at three months and the last follow-up after operation were obviously improved in their VAS, JOA, and NDI scores (P<0.05). There was no significant difference between the scores at last follow-up and 3 months after operation. Cervical lordosis changed from (10.64±4.26)° preoperatively to (13.68±4.56) ° at the last follow-up;the FSU curvature from (5.40±0.41) °to (9.92±2.00) °at the last follow-up (P<0.05). The range of motion of the cervical spine preoperatively, 3 month postoperatively, and at the last follow-up were(70.84±6.17)°, (60.00±6.58)°, (71.48±4.61)°; FSU activities were(12.00±0.49)°, (9.36±0.26)°, (12.52±0.33)°;the activities of replacement segment were (10.48±0.67)°, (7.24±0.34)°, (9.28±0.36)°;the activities of upper segment of replacement were (10.52±0.60)°, (8.60±0.30)°, (10.44±0.43)°;the activities of lower segment of replacement were (8.48±0.40)°, (6.56±0.36)°, (9.60±0.39)°;there were significant differences in above items preoperatively and 3 months postoperatively(P<0.05); and there were no significant difference preoperatively and at the last follow-up(P>0.05). Pharyngeal discomfort and hoarseness occurred in 5 cases, and were recovered within 2 weeks after operation;heterotopic ossification occurred in 1 case at 6 months after operation;displacement of prosthesis occurred in 1 case at 12 months after operation. Based on Odom standard to evaluate the clinical outcome, 20 cases obtained excellent results, with 27 good, 2 general. Bryan artificial cervical disc replacement not only generate good clinical effects, but may also restore the cervical lordosis and FSU curvature, while retaining the activities of replacement segment, and restoring overall cervical biomechanical functions.

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 Analysis of Bryan Cervical Artificial Disc Replacement for "Skip" Multi-Segment Cervical Spondylosis: Long-Term Follow-Up Results.

BackgroundThe aim of this study was to retrospectively analyze the clinical and radiological efficacy of Bryan cervical artificial disc replacement (ADR) for “skip” multi-segment cervical spondylosis (SCS).Material/MethodsWe enrolled 49 patients with SCS treated with either Bryan cervical ADR (18 cases) or ACDF (31 cases). Each case was evaluated preoperatively and at more than 48 months postoperatively in follow-up using the JOA, NDI, and VAS. Cervical sagittal curvature, total cervical ROM, and degree of middle segments of motion were also evaluated. MRI was used to assess adjacent segment degeneration(ASD), spinal cord compression, and signal changes.ResultsThe JOA, NDI, and VAS scores in the 2 groups improved significantly postoperatively. At the last follow-up, the results of Group Bryan were better than those of Group ACDF with respect to the incidence of axial symptoms (11.1% and 45.2%, respectively), VAS, ROM, and the degree of middle segments of motion. The ROM in Group Bryan was 38.2±4.6° and in Group ACDF was 25.3±4.6°. The middle segments of motion were 8.4±2.0° in Group Bryan and 12.2±2.2° in Group ACDF. There were no patients with ASD in Group Bryan. In Group ACDF, 1 case with an internal fixation device developed dislocation, and 2 cases developed degeneration, but there was no need for reoperation.ConclusionsADR for SCS can effectively improve neurological function and retain the overall activity of the cervical, thereby reducing ASD and the incidence of postoperative axial symptoms.

Comparison of the mid-term follow-up results between Bryan cervical artificial disc replacement and anterior cervical decompression and fusion for cervical degenerative disc disease

Objective To evaluate the mid-term tollow-up results of cervical artificial disc replacement (CADR) for cervical degenerative disc disease,and to explore whether it can reduce the occurrence of adjacent segment degeneration (ASD).Methods A prospective comparative study of 93 patients who underwent CADR or anterior cervical decompression and fusion (ACDF) for cervical degenerative disc disease were conducted.All patients were followed up for more than 6 years.The Japanese Orthopaedic Association (JOA) score,neck disability index (NDI),Odom's scale,X-rays and magnetic resonance imaging (MRI) were used to evaluate the clinical and radiologic results.Results Twenty eight patients who underwent CADR and 35 patients who underwent ACDF had complete follow-up data.At final follow-up,the JOA score and NDI improved significantly in both groups.Between the two groups,there was no significant difference in terms of JOA score,NDI and Odom's scale.The sagittal alignment was well maintained in both groups.The total cervical spine range of motion (ROM) had no significant change for the CADR group,whereas,it significantly decreased for the ACDF group.The ROM at the replacement level of CADR patients decreased from 9.5° ± 3.7° before operation to 7.0° ± 3.0° 3 months after operation,and it was maintained to 6.6° ± 4.1° at final follow-up without significant decrease.Lateral radiographs and T2-weighted MRI showed the incidence of ASD in CADR group was significantly lower than that in ACDF group.Conclusion The six-year follow-up results of CADR are basically satisfactory.Compared with ACDF,it could better preserve physiological motion and biomechanics of cervical spine,and reduce the incidence of ASD. Key words: Cervical vertebrae; Intervertebral disk; Prosthesis implantation; Spinal fusion; Follow-up studies

Comparison of Motion Changes and Clinical Outcomes between Cervical Disc Replacement and Anterior Cervical Discectomy and Fusion in Single Level Cervical Degenerative Disease: Retrospective Analysis

Objective: Cervical Total Disc Replacement (CTDR) has recently been developed as an alternative to Anterior Cervical Discectomy and Fusion (ACDF) in cervical degenerative disease to preserve the motion at the treated level. The aim of this study is to investigate the safety and efficacy of CTDR by comparing it with ACDF in the treatment of single-level cervical degenerative disease, retrospectively. Methods: This study included 61 patients, who underwent either stand-alone single-level ACDF (n = 33) or singlelevel CTDR (Bryan cervical artificial disc, n = 28) at C3 to C7 for degenerative cervical disease between June 2007 and December 2009. Cervical radiographs were obtained to measure overall and regional cervical angle and Range of Motion (ROM). For evaluation for patient’s pain, visual analogue scale and Japanese Orthopedic Association score was measured. Results: The changes of the overall Cervical Sagittal Angle (CSA) were not significantly different between the two groups. The Segmental Angle (SA) was maintained at a significantly higher in the CTDR group compared to the ACDF group during the follow-up period (p < 0.05). The ROM of the upper adjacent segment was significantly increased in the ACDF group compared to the CTDR group. Conclusions: Clinically, CTDR is at least as efficient as ACDF. CTDR using a Bryan artificial disc provided a significant maintenance of the SA and the ROM at the treated level, and prevented the hyper-mobility at the upper adjacent segment compared to the ACDF. In the Future, prospective, randomized, long-term follow-up study with large-number will be required to clarify the efficacy of CTDR.

The Intermediate Clinical Outcome and Its Limitations of Bryan Cervical Arthroplasty for Treatment of Cervical Disc Herniation

This is a prospective, consecutive series study to determine the role of the Bryan artificial cervical disc replacement to treat the isolated cervical disc herniation for Chinese patients. To evaluate the intermediate clinical outcome and its limitations of Bryan cervical disc replacement in the management of isolated cervical disc herniation in Chinese patients. Observing neurological improvement and the radiographic finding. Most people believe that anterior cervical fusion is a factor that shall not be ignored in adjacent segment degeneration. Artificial cervical disc replacement, as a nonfusion technique, may offer a solution to this problem. The clinical outcome of cervical arthroplasty in oriental patients is not often seen in English literature. The variation of anatomic index in Asian patients was also not considered enough. There were consecutive series of 45 patients with cervical disc herniation. The herniated disc was located at C3-4 in 2 cases, at C4-5 in 8 cases, at C5-6 in 24 cases, at C6-7 in 5 cases, at C4-5, 5-6 in 2 cases, at C3,4, 5-6 in 1 cases, and at C 5-6, 6.7 in 3 cases. There were 19 patients with myelopathy and 26 patients with radiculopathy. A total of 51 sets of Bryan cervical disc prosthesis were implanted. The follow-up ranges from 24 to 70 months. The clinical symptom and the neurological function were evaluated. The level of stableness and mobility at the implanting location were observed on dynamic radiograph postoperatively. A total of 51 Bryan cervical disc prosthesis were implanted. Single-level disc was replaced in 39 cases whereas bilevel in 6 cases. The follow-up ranges from 24 to 70 months, with an average of 35 months. Patients showed significant improvement in neurological symptoms. The JOA score (17 points) was from 10.2 increased to 15.4 at final follow-up. The neck disability index was from 43.5 reduced to 28.4 at final follow-up. The clinical success (excellent/good/fair) according to Odom' Criteria were 89.8%. The average range of motion at implant level was 9.3 degrees, postoperatively. Migration of artificial disc greater than 2 mm was not observed. Resorption at the inferior edge of anterior surface of upper vertebral body were seen in 3 patients, Two patients had II grade heterotopic ossification. One patient had a definite spontaneous fusion of treated segment after 4 years of follow-up. There was some difficulty for exact matched implant in small group patients owing to the variation of anatomic index in oriental patients. Cervical arthroplasty had a good intermediate clinical outcome for oriental patients. Definite stabilization and satisfactory mobility were achieved after surgery, with significant neurological symptom improvement observed. For better matched implant, more shapes/sizes of artificial cervical disc need to be made available for the oriental patients.

Fusion versus Bryan Cervical Disc in two-level cervical disc disease: a prospective, randomised study

In this prospective study, our aim was to compare the functional results and radiographic outcomes of fusion and Bryan Cervical Disc replacement in the treatment of two-level cervical disc disease. A total of 65 patients with two-level cervical disc disease were randomly assigned to two groups, those operated on with Bryan Cervical Disc replacement (31) and those operated on with anterior cervical fusion with an iliac crest autograft and plate (34). Clinical evaluation was carried out using the visual analogue scale (VAS), the Short Form 36 (SF-36) and the neck disability index (NDI) during a two year follow-up. Radiological evaluation sought evidence of range of motion, stability and subsidence of the prosthesis. Substantial reduction in NDI scores occurred in both groups, with greater percent improvement in the Bryan group (P = 0.023). The arm pain VAS score improvement was substantial in both groups. Bryan artificial cervical disc replacement seems reliable and safe in the treatment of patients with two-level cervical disc disease.

Motion Analysis of Bryan Cervical Disc Arthroplasty Versus Anterior Discectomy and Fusion: Results From a Prospective, Randomized, Multicenter, Clinical Trial

Prospective, randomized, multicenter clinical trial. Kinematic analysis of target level and adjacent motion segments after Bryan artificial cervical disc replacement versus anterior cervical fusion. Disc arthroplasty has been shown to provide short-term clinical results that are comparable or better than those attained with traditional anterior cervical discectomy and fusion. One purported benefit of arthroplasty is the ability to prevent or delay adjacent level operations. All patients received either a single-level anterior cervical discectomy and fusion with an anterior cervical plate (Atlantis anterior cervical plate, n=221) or a single-level artificial cervical disc replacement (Bryan cervical disc prosthesis, n=242) at C3 to C7. Flexion, extension, and neutral lateral radiographs were obtained preoperatively, and at regular intervals of 24 months. Cervical vertebral bodies were tracked to calculate the functional spinal unit motion parameters, including flexion/extension range of motion and translation. If visible, the functional spinal unit parameters were obtained at the operative level as well as the level above and below. Significantly more motion was retained in the disc replacement group than the plated group at the index level. The disc replacement group retained an average of 7.95 degrees at 24 months. The preoperative motion was 6.43 degrees and there was no evidence of degradation of motion over 24 months. In contrast, the average range of motion in the fusion group was 1.11 degrees at 3-month follow-up and gradually decreased to 0.87 degrees at 24 months. The preoperative motion was 8.39 degrees. The Bryan disc did not migrate. At 24-month follow-up, there was no case of subsidence of the Bryan disc. There was no evidence of bridging bone across any of the Bryan implant disc spaces. The Bryan disc treatment, on average, maintained flexion/extension range of motion without degradation over 24 months. No ectopic bridging ossification was seen in any of the Bryan discs and no subsidence or displacement of the Bryan disc occurred.

Clinical and radiographic reports following cervical arthroplasty: a 24-month follow-up

We reviewed patients with cervical disc prosthesis replacement for single-level cervical disc disease to evaluate its clinical effect and maintenance of cervical spine motion. Fifteen patients underwent Bryan artificial cervical disc replacement and were followed-up for at least 24 months. No neurological or vascular complications were observed during or after operation. JOA, VAS, and NDI scores showed statistical significant improvement in our follow-up. The procedure achieved an 87% (13/15) satisfactory rate at 24-month evaluations according to Odom's criteria. The range of motion (ROM) of the cervical spine, treated segment, adjacent segment, and functional spinal unit (FSU) decreased at early follow-up, but they recovered to the preoperative level at 12- and 24-month follow-up. Also, preoperative lordosis of the cervical spine and FSU were not only maintained but also even improved during the 24-month follow-up. No obvious degeneration of adjacent discs were found at MRI. There were no cases of prosthesis subsidence or extrusion. The cervical disc prosthesis showed a good clinical outcome; it also restored ROM of the cervical spine and reestablished cervical curvature in our 24-month follow-up. But to be sure of its long term effect, a longer follow-up is needed.

Comparison of Adverse Events Between the Bryan Artificial Cervical Disc and Anterior Cervical Arthrodesis

Randomized controlled study. To compare the rates of adverse events associated with disc arthroplasty versus those of anterior cervical discectomy and arthrodesis with allograft and plate. Cervical disc arthroplasty as a substitute for fusion has been developed to maintain motion and, theoretically, prevent adjacent segment degeneration. Currently, cervical arthroplasty devices are undergoing clinical testing for safety and efficacy. The evaluation of safety is performed by critical analysis of all adverse occurrences following surgery to determine if the new device has a beneficial risk profile for the patient. Adverse events associated with Bryan Disc arthroplasty and arthrodesis were compared in a prospective randomized study. Four hundred sixty-three (463) patients having cervical radiculopathy and or myelopathy at a single level were treated at 31 sites. A total of 242 patients received the disc and 221 patients had anterior cervical discectomy and fusion. All patients were evaluated before surgery and at 1.5, 3, 6, 12, and 24 months after surgery. Adverse events were recorded concurrently and categorized by severity and as medically or surgically related. No differences in overall medical events occurred between groups. Surgically related events occurred more frequently in the investigational group secondary to more complaints of postoperative dysphagia and late medical events occurred more frequently in the investigational patients. However, the more severe World Health Organization Grade 3 and 4 events occurred more frequently in the arthrodesis patients related to treatment of pseudarthrosis and persistent symptoms. Significantly, more cervical spine reoperations occurred in the fusion group. Only one spinal cord injury occurred and it was in the arthrodesis group and no patients had deep infection or death related to either procedure. Bryan cervical disc replacement and anterior cervical fusion are both safe procedures with a low incidence of significant adverse events related to the procedure. Statistically, more serious adverse events and reoperations occurred in the fusion group while a greater number of less serious surgically related events were seen in the investigational group.

Early and Intermediate Follow-up Results After Treatment of Degenerative Disc Disease With the Bryan Cervical Disc Prosthesis

Our clinical study design was prospective, concurrently enrolled and single-center trial of the new functional intervertebral cervical disc prosthesis (Medtronic Sofamor Danek, Memphis, TN) in the treatment of patients with single-level and multiple-level degenerative disc disease of the cervical spine. The study was designed to investigate the surgical technology skills and clinical effects of Bryan cervical disc prosthesis in Chinese, and to observe the stability and range of movement in the early and immediate postoperative period. Recently, motion preservation has come to the forefront of emerging technologies in spine surgery. This is the important background information of the emergence of cervical arthroplasty as an alternative to arthrodesis that offers the promise of restoring normal spinal movement and reduces a kinematic strain on adjacent segments. Nineteen patients (23 discs) had spinal arthroplasty with placement of the Bryan cervical artificial disc prosthesis in our hospital. Clinical and radiologic follow-up was performed. The radiographic parameters evaluated included the treated segments and the overall curvature of the cervical spine. All the patients were observed up from 8 months to 42 months (average 24 months). According to Odom's scale, all of 19 patients (23 levels) had excellent to good outcome. The range of movement recovered to the preoperative value during the follow up. The treated segment ultimately showed preservation of movement when compared with preoperative levels. No prosthesis subsidence or excursion was identified. Arthroplasty using the Bryan disc seemed to be safe and provided encouraging clinical and radiologic outcome in our study. Although early and intermediate results are promising, this is also a relatively new approach, long-term follow up studies are required to prove its efficacy and its ability to prevent adjacent segment disease.

Functional evaluation of the cervical spine after Bryan artificial disc replacement

To assess the effect of Bryan cervical disc replacement on the function of the cervical spine. Bryan cervical artificial disc replacement was performed in 164 cases from Dec 2003 to Aug 2007, and all the cases were retrospectively followed up. Among them, 1 disc replacement was done in 132 cases, 2 discs in 28 cases and 3 discs in 4 cases with a total number of 200 artificial discs. There were 102 male patients and 62 female patients. Their age ranged from 25 to 70 years old (with an average of 47 years old). All the cases were operated according to the standard procedure for Bryan artificial disc replacement, and immobilized in a cervical collar for 2 weeks after operation. Motion of the replaced disc in sagittal direction, JOA score and satisfaction rate of the patients were followed up and evaluated. In this group, no acute complications happened during the operation. All patients returned to work 4 to 6 weeks after operation. The postoperative ameliorate rate of JOA score was 56%. Range of motion in sagittal direction of the operated disc was 14.4 degrees before operation, decreased to 5.7 degrees at 1 week after operation , but improved to 14.7 degrees at the time of final follow-up and was not significantly different from preoperative range. Motion in the upper adjacent disc to the replacement level was 10.9 degrees before operation, decreased to 5.5 degrees at 1 week after operation , and improved to 8.2 degrees at the time of final follow-up but was significantly smaller than preoperative range. The satisfaction rate of the patients was 94%. Loosening of the prosthesis happened in 1 case 6 months after operation but remained stable afterwards. Subsidence up to 1 mm occurred in another case 7 months after operation but also remained stable afterwards. Automatic posterior union occurred in 3 cases in which relative small size artificial discs were implanted. The clinical outcome of Bryan artificial disc replacement was quite good. Pre-operative range of motion of the cervical spine can be maintained.

Artificial Disc Versus Fusion

A total of 115 patients were randomized in a 1:1 ratio to a Bryan artificial disc replacement (56) or an anterior cervical fusion with allograft and a plate (59). The purpose of this study is to examine the functional outcome and radiographic results of this prospective, randomized trial to determine the role of the Bryan artificial cervical disc replacement for patients with 1-level cervical disc disease. Artificial cervical disc replacement has become an option for cervical radiculopathy. Previous studies have evaluated the efficacy of this alternative without the scientific rigor of a concurrent control population. This study is a pooled data set from 3 centers involved in the U.S. FDA Investigational Device Exemption trial evaluating the Bryan artificial cervical disc. The purpose of this study is to examine the functional outcome and radiographic results of this prospective, randomized trial to determine the role of the Bryan artificial cervical disc replacement for patients with 1-level cervical disc disease; 12-month follow-up is available for 110 patients and 24 month follow-up complete for 99 patients. There are 30 males and 26 females in the Bryan group and 32 males and 27 females in the fusion group. The average age was 43 years (Bryan) and 46 years (fusion). Disability and pain were assessed using the Neck Disability Index (NDI) and the Visual Analog Scale (VAS) of the neck and of the arm pain. SF-36 outcome measures were obtained including the physical component as well as the mental component scores. Range of motion was determined by independent radiologic assessment of flexion-extension radiographs. We report a prospective, randomized study comparing the functional outcome of cervical disc replacement to an anterior cervical fusion with results of 99 patients at 2 years. Prospective data were collected before surgery and at 6 weeks, 3, 6, 12, and 24 months after surgery. The average operative time for the control group was 1.1 hours and the Bryan Group 1.7 hours. Average blood loss was 49 mL (control) and 64 mL (Bryan). Average hospital stay was 0.6 days (control) and 0.9 days (Bryan). The mean NDI before surgery was not statistically different between groups: 47 (Bryan) and 49 (control). Twelve-month follow-up NDI is 10 (Bryan) and 18 (control) (P = 0.013). At 2-year follow-up, NDI for the Bryan group is 11 and the control group is 20 (P = 0.005). The mean arm pain VAS before surgery was 70 (Bryan) and 71 (control). At 1-year follow-up, Bryan arm pain VAS was 12 and control 23 (P = 0.031). At 2-year follow-up, the average arm pain VAS for the Bryan group was 14 and control 28 (P = 0.014). The mean neck pain VAS before surgery was 72 (Bryan) and 73 (control). One-year follow-up scores were 17 (Bryan) and 28 (control) (P = 0.05). At 2 years: 16 (Bryan) and 32 (control) (P = 0.005). SF-36 scores: Physical component--Before surgery Bryan 34 and control 32. At 24 months: Bryan 51 and control 46 (P = 0.009). More motion was retained after surgery in the disc replacement group than the plated group at the index level (P < 0.006 at 3, 6, 12, and 24 months). The disc replacement group retained an average of 7.9 degrees of flexion-extension at 24 months. In contrast, the average range of motion in the fusion group was 0.6 degrees at 24 months. There were 6 additional operations in this series: 4 in the control group and 2 in the investigational group. There were no intraoperative complications, no vascular or neurologic complications, no spontaneous fusions, and no device failures or explantations in the Bryan cohort. The Bryan artificial disc replacement compares favorably to anterior cervical discectomy and fusion for the treatment of patients with 1-level cervical disc disease. At the 2-year follow-up, there are statistically significant differences between the groups with improvements in the NDI, the neck pain and arm pain VAS scores, and the SF-36 physical component score in the Bryan disc population.

Effects of a cervical disc prosthesis on maintaining sagittal alignment of the functional spinal unit and overall sagittal balance of the cervical spine

The object of this study is to review the early clinical results and radiographic outcomes following insertion of the Bryan Cervical Disc Prosthesis (Medtronic Sofamor Danek, Memphis, TN), together with its effect on maintaining sagittal alignment of the functional spinal unit (FSU) and overall sagittal balance of the cervical spine for the treatment of single-level or two-level symptomatic disc disease. Forty-seven patients with symptomatic single or two-level cervical disc disease who received the Bryan Cervical Artificial Disc were reviewed prospectively. A total of 55 Bryan disc were placed in 47 patients. A single-level procedure was performed in 39 patients and a two-level procedure in the other eight. Radiographic and clinical assessments were made preoperatively and at 1.5, 3, 6, 9, 12, and 18 and up to 33 months postoperatively. Mean follow-up duration was 24 months, ranging from 13 to 33 months. Periods were categorized as early follow up (1.5-3 months) and late follow up (6-33 months). The visual analogue scale (VAS), neck disability index(NDI), Odom's criteria were used to assess pain and clinical outcomes. Static and dynamic radiographs were measured by hand and computer to determine the range of motion (ROM), the angle of the functional segmental unit (FSU), and the overall cervical alignment (C2-7 Cobb angle). With all of these data, we evaluated the change of the preoperative lordosis (or kyphosis) of the FSU and Overall sagittal balance of the cervical spine during the follow-up period. There was a statistically significant improvement in the VAS score from 7.0 +/- 2.6 to 2.0 +/- 1.5 (paired-t test, P = 0.000), and in the NDI from 21.5 +/- 5.5 to 4.5 +/- 3.9 (paired-t test P = 0.000). All of the patients were satisfied with the surgical results by Odom's criteria. The postoperative ROM of the implanted level was preserved without significant difference from preoperative ROM of the operated level. Only 36% of patients with a preoperative lordotic sagittal orientation of the FSU were able to maintain lordosis following surgery. However, the overall sagittal alignment of the cervical spine was preserved in 86% of cases at the final follow up. Interestingly, preoperatively kyphotic FSU resulted in lordotic FSU in 13% of patients during the late follow-up, and preoperatively kyphotic overall cervical alignment resulted in lordosis in 33% of the patients postoperatively. Clinical results are encouraging, with significant improvement seen in the Bryan Cervical Artificial disc. The Bryan disc preserves motion of the FSU. Although the preoperative lordosis (or kyphosis) of the FSU could not always be maintained during the follow-up period, the overall sagittal balance of the cervical spine was usually preserved.

Assessment of adjacent-segment disease in patients treated with cervical fusion or arthroplasty: a prospective 2-year study

The authors compared the incidence of radiologically documented changes and symptomatic adjacent-level cervical disc disease after single-level discectomy and subsequent cervical fusion or arthroplasty in two independent prospective clinical studies. The patients were treated with the Affinity Anterior Cervical Cage System or the Bryan Artificial Cervical Disc. In each study the patients were required to undergo serial cervical radiography preoperatively and 24 months postoperatively, as well as serial clinical evaluations including documentation of adverse events, neurological status, and results of the 36-item Short Form Health Survey. All serial radiographs were reviewed prior to evaluating the clinical symptoms for development of increasing or new adjacent degenerative disc disease (DDD). Subsequently, the clinical data were analyzed. For various reasons of exclusion, the cases analyzed in the Bryan disc-treated cohort consisted of 74 patients and in the Affinity system-treated cohort there were 158 patients. New anterior osteophyte formation or enlargement, increased narrowing of an interspace, new DDD, and calcification of the anterior longitudinal ligament were the radiological findings indicative of adjacent-level disease. Fusion was associated with a significant increase in x-ray film-based changes of adjacent-disc disease (p = 0.009, odds ratio [OR] 2.44). In the cage fusion series, the incidence of symptomatic adjacent-level DDD was statistically greater than that in the group treated with the artificial disc (p = 0.018), and the patients required a statistically greater number of medical treatments related to episodic symptoms of neck, shoulder, and arm pain attributed to new disc disease (p = 0.001, OR 35.8). In comparing these prospective studies the authors demonstrated that maintaining motion rather than fusion will prevent symptomatic adjacent-disc disease and will decrease adjacent-level radiological indicators of disease at a 24-month postoperative interval.

Cervical arthroplasty after previous surgery: results of treating 24 discs in 15 patients

The potential role of cervical arthroplasty in patients who have undergone previous cervical surgery is unknown. The authors performed a prospective study involving nonrandomized clinical and radiological assessment in patients who had undergone either previous posterior cervical foraminotomy or anterior interbody fusion and who suffered new or persistent arm/neck symptoms related to neural compression. During a 30-month period, 15 patients who had previously undergone cervical spinal surgery underwent cervical arthroplasty that involved placement of the Bryan disc for neck or arm symptoms related to cervical disc disease. A total of 24 devices were implanted. Six of the 15 patients had undergone a previous posterior foraminotomy, and in nine cases an anterior interbody fusion had been perfomed at some stage prior to surgery. Clinical and radiological evaluations were performed preoperatively and after surgery to assess outcomes. A total of 24 arthroplasties were performed encompassing between one and three levels. There were no major perioperative complications or immediate device-related failures. Two patients were lost to follow up. The follow-up period ranged from 12 to 43 months (mean 24.2 +/- 10.5 months). Good results were obtained in all cases as reflected by an increase in the visual analog scale score of 6.4 in terms of neck/arm pain (p < 0.05). There was no difference in Oswestry Disability Index scores for neck pain (p > 0.05) and no patient required surgery at the same level. In one patient hypermobility developed with internal subluxation of the device, which suggested a compromise adjacent to a two-level fusion at 21 months. The segment was hypermobile preoperatively. The patient has experienced recurrent neck pain but otherwise remains clinically well and has not required revision surgery to date. Insertion of the Bryan artificial cervical disc in patients who have previously undergone cervical fusion or posterior foraminotomy, in general, appears to be safe. It provided encouraging early clinical results, although patients with preoperative hypermobility should be treated with caution. Issues such as accelerated device-related wear and the use of arthroplasty after aggressive facetectomy resection will need further study; however, in carefully selected patients who have undergone previous surgery cervical arthroplasty may provide an additional tool in the management of cervical disc disease.