The Clinical and Radiological Effect of Abnormal Axis after Cervical Arthroplasty

OBJECTIVE: The clinical outcomes according to the radiological results after cervical total disc replacement (TDR) are not well established. Here, the authors reviewed the clinical results according to the asymmetry in radiographs. METHODS: This retrospective analysis included patients after TDR (Mobi-C(R) disc) with at least 12 months follow up, and the clinical and radiological data were obtained preoperatively and postoperatively for 12 months. Clinical outcome measures numerical rating scale (NRS) score for neck pain, visual analog scale (VAS) for arm pain, and the Oswestry disability index (ODI) value. The asymmetries of TDRs were evaluated on the anterior-posterior (AP) and the lateral radiographs, and the radiographic adjacent segment degenerations were evaluated for 12 months. RESULTS: A total of 24 patients (one level cervical TDR; 10 male and 14 female; aged 41.50+/-8.35 years) were included in this study. The clinical results including NRS for neck pain, VAS for arm pain, and ODIs were similar between the normal and asymmetrized TDRs in AP and lateral radiographs. The radiographic adjacent segment degenerations were significantly increased in deviated TDRs (AP>10 mm asymmetry and lateral>10 mm asymmetry). CONCLUSION: Asymmetrical location of TDR is not related to the clinical outcomes, but related to the risk of radiographic adjacent disc segment degeneration.

Cervical Arthroplasty for Moderate to Severe Disc Degeneration: Clinical and Radiological Assessments after a Minimum Follow-Up of 18 Months: Pfirrmann Grade and Cervical Arthroplasty

PURPOSE: Clinical outcomes and radiologic results after cervical arthroplasty have been reported in many articles, yet relatively few studies after cervical arthroplasty have been conducted in severe degenerative cervical disc disease. MATERIALS AND METHODS: Sixty patients who underwent cervical arthroplasty (Mobi-C(R)) between April 2006 and November 2011 with a minimum follow-up of 18 months were enrolled in this study. Patients were divided into two groups according to Pfirrmann classification on preoperative cervical MR images: group A (Pfirrmann disc grade III, n=38) and group B (Pfirrmann disc grades IV or V, n=22). Visual analogue scale (VAS) scores of neck and arm pain, modified Oswestry Disability Index (mODI) score, and radiological results including cervical range of motion (ROM) were assessed before and after surgery. RESULTS: VAS and mean mODI scores decreased after surgery from 5.1 and 57.6 to 2.7 and 31.5 in group A and from 6.1 and 59.9 to 3.7 and 38.4 in group B, respectively. In both groups, VAS and mODI scores significantly improved postoperatively (p<0.001), although no significant intergroup differences were found. Also, cervical dynamic ROM was preserved or gradually improved up to 18 months after cervical arthroplasty in both groups. Global, segmental and adjacent ROM was similar for both groups during follow-up. No cases of device subsidence or extrusion were recorded. CONCLUSION: Clinical and radiological results following cervical arthroplasty in patients with severe degenerative cervical disc disease were no different from those in patients with mild degenerative cervical disc disease after 18 months of follow-up.

Heterotopic Ossification after Cervical Arthroplasty with ProDisc-C: Time Course Radiographic Follow-up over 3 years

OBJECTIVE: Heterotopic ossification (HO) is a well-known complication after total hip replacement. But the occurrence rate by the time-course, clinical effect and risk factors of HO after total cervical disc replacement (TCDR) are not well described. The purpose of this study is to evaluate the occurrence rate by the time-course and risk factors for HO after TCDR with a ProDisc-C. METHODS: Thirty-two patients whom followed up more than one year after the TCDR are enrolled. Radiographic study was done at 12, 24 and 36 months after the TCDR and classified HO with McAfee classification. Segmental range of motion, preoperative existence of spondylosis, type of operation, disc space occupying ratio by artificial disc, surgical level are analyzed to identify the risk factors of HO. The visual analog scale and the neck disability index were evaluated preoperatively and at last follow-up time for clinical parameters. RESULTS: Eighteen patients (56%) showed HO at 12 months, 18 patients (86%) showed HO at 24 months and 6 patients (89%) showed HO at 36 months after the TCDR. Clinical significant HO(Grade 3 and 4) was shown in one patient (3%) at 12 months, 3 patients (14%) at 24 months and 5 patients (56%) at 36 months. Only post-operative follow-up period increases the risk of development clinical significant HO. All patients showed improvement of clinical parameters (p<0.005). CONCLUSION: Incidence of HO is getting higher as time course progress. However, there are no relation between clinical outcome and radiologic change of ROM and the grade of HO.

Heterotopic Ossification Following Cervical Total Disc Replacement: Iatrogenic or Constitutional?

OBJECTIVE: To elucidate etiological factors of heterotopic ossification (HO) by evaluating retrospectively if HO is a unique finding following cervical total disc replacement (CTDR) or a finding observable following an anterior cervical interbody fusion (ACIF). METHODS: The authors had selected 87 patients who underwent anterior cervical surgery (TDR or ACIF), and could be followed up more than 24 months. A cervical TDR was performed using a Bryan disc or a ProDisc-C and an ACIF using a stand-alone cage or fibular allograft with a plate and screws system. The presence of HO was determined by observing plain radiography at the last follow up. The relation between HO occurrence and specific preoperative radio-logical findings (osteophyte and calcification of posterior longitudinal ligament (PLL)) at the index level was investigated. RESULTS: Cervical TDR was performed in 40 patients (43 levels) and ACIF in 47 patients (54 levels). At the final radiographs, HO was demonstrated at 27 levels (TDR-Bryan; 8/18, TDR-Prodisc-C; 12/25, ACIF-cage alone; 7/29, and ACIF-plate screw; 0/25). Mean ROM at the last follow-up of each TDR subgroup were 7.8+/-4.7degrees in Bryan, 3.89+/-1.77degrees in Prodisc-C, and it did not correlated with the incidence of HO. Fusion status of ACIF groups was observed as 2 case of grade 1, 6 of grade 2, and 21 of grade 3 in cage alone subgroup, and no case of grade 1, 4 of grade 2, and 21 of grade 3 in plate screw subgroup. Fusion status in ACIF-cage alone subgroup was significantly related to the HO incidence. The preoperative osteophyte at the operated level observed in 27 levels, and HO was demonstrated in 12 levels (TDR-Bryan; 3/5, TDR-Prodisc-C; 2/3, ACIF-cage alone; 7/11, and ACIF-plate screw; 0/8). Preoperative PLL calcification at the operated level was observed 22 levels, and HO was defined at 14 levels (TDR-Bryan; 5/5, TDR-Prodisc-C; 4/5, ACIF-cage alone; 5/7, and ACIF-plate screw; 0/5). The evidence of preoperative osteophyte and PLL calcification showed statistically significant relations to the occurrence of HO. CONCLUSION: HO was observed in both TDR and ACIF groups. HO was more frequently occurred in TDR group regardless of prosthesis type. In ACIF group, only cage alone subgroup showed HO, with relation to fusion status. Preoperative calcification of longitudinal ligaments and osteophyte were strongly related to the occurrence of HO.

Comparative Analysis of Cervical Disc Arthroplasty Using Two Types of Artificial Cervical Discs: Bryan(R) versus Mobi-C(R)

OBJECTIVE: Since the 1990s, due to postoperative loss of mobility and adjacent segmental disease after anterior cervical fusion, many different types of cervical artificial discs have been developed as alternative implants. The purposes of this study are investigation and comparison of radiographic and clinical outcomes between two different types of prostheses, Bryan(R) and Mobi-C(R). METHODS: We retrospectively evaluated 33 patients who were treated for cervical degenerative disc disease that resulted in radiculopathy and/or myelopathy between May 2004 and April 2009. Seventeen patients underwent Bryan(R) cervical disc arthroplasty and sixteen patients underwent Mobi-C(R) arthroplasty. The radiographic outcomes were assessed by measuring the cervical lordosis, segmental lordosis, range-of-motion (ROM) of the cervical spine (C2-7), functional segmental unit (FSU), prosthesis' shell and the upper adjacent segment. The clinical results were evaluated according to the Visual Analogue Scale (VAS) for axial pain and radiculopathy, Odom's criteria, and the modified Prolo's economic and functional outcome rating scale. RESULTS: The age of the study population ranged from 24 to 69 years with a mean age of 48 years vs. 46 years in the Bryan(R) and Mobi-C(R) groups, respectively. The mean duration of follow-up was 23.7 months in the Bryan(R) group and 11.3 months in the Mobi-C(R) group. The changes of overall cervical sagittal angle were not significantly different between two groups, but the increase of segmental sagittal angle (0.85degrees in Bryan(R), 8.04degrees in Mobi-C(R)), ROM of the FSU(-0.51degrees in Bryan(R), 2.47degrees in Mobi-C(R)) and ROM of the shell (1.77degrees in Bryan(R), 5.28degrees in Mobi-C(R)) were significantly higher in Mobi-C(R) group than in Bryan(R) group (p<0.05). The clinical results were not significantly different between two groups. CONCLUSION: The Mobi-C(R) prosthesis showed more favorable radiographic results than that of the Bryan(R) prosthesis, however, the clinical outcomes were similar in both groups. Large-scale and long-term follow-up studies are needed to confirm our results.

Resultados tempranos de la artroplastía cervical utilizando Prodisc-C / Early results of cervical artroplasty with Prodisc-C

Introducción. La utilización del disco artificial cervical (artroplastía) es una técnica relativamente nueva, que se presenta como una alternativa a la ya clásica cirugía de discectomía y fusión que se usa para las lesiones degenerativas de la columna cervical subaxial. El desarrollo de esta técnica obedece a la necesidad de encontrar un diseño que permita reproducir de manera fisiológica la función del disco intervertebral. Material y Método. Entre los meses de julio de 2005 y junio de 2007, en el Servicio deNeurocirugía de la Clínica Güemes de Luján, se realizaron 35 artroplastías cervicales en 27 pacientes. La edad promedio fue de 43,4 años, con un rango entre el paciente más joven 28 años y 54 el mayor. Los pacientes fueron evaluados en el preoperatorio y a los 45 días, 3, 6 y 12 meses Resultados. Observamos una gran mejoría tanto con la evaluación del cuestionario Neck Disability Index (NDI) en los primeros controles como con la escala analógica visual (VAS). Esta mejoría, si bien se mantuvo hasta gran parte de nuestra etapa de control, al año mostró un ligero aumento de la sintomatología, pero sin salir de los parámetros que consideramos como satisfactorios. Conclusión. Para pacientes jóvenes con historia de dolor cervical y/o radicular de 3 meses de evolución o más, el empleo del ProDisc- C, por sus beneficios, se presenta como una excelente opción para el tratamiento de la hernia de disco cervical.

Introduction. The use of an artificial cervical disc is a new technique that can replace the classical discectomy and fusion for lesion in the lower cervical spine. The purpose of this design is to reproduce the function of the intervertebral disc. Method. Between July 2004 and June 2007, 35 cervical arthroplasties were performed at Clinica Guemes, Lujan. 27 patients underwent a single or double disc replacement. The average age was 4A��3.4 years (range 28-54). The patients were evaluated 45, 90, 180 and 365 days after surgery. The patients were evaluated using Neck Disability Index (NDI) and Visual Analogic Scale (VAS). Results. A steady improvement could be observed in all patients tested by both scales. Conclusion. The use of ProDisc-C in young patients appear to be an excellent option for the treatment of cervical disc herniation.

Clinical and Radiographic Analysis of Cervical Total Disc Replacement Versus Anterior Cervical fusion using Stand-alone Cage

OBJECTIVE: Total intervertebral disc replacement is designed to preserve motion and avoid limitations of fusion after removing local pathology. The authors report the results of a signle-center study to determine functional and radi- ologic outcomes associated with cervical total disc replacement versus those of cervical fusion. METHODS: We retrospectively reviewed the charts and radiographs of patients who underwent a total intervertebral disc replacement(TDR) or a single-level anterior cervical fusion(ACDF) between January 1, 2004, and September 31, 2007. Clinical symptom was assessed using the Visual Analog Scale(VAS) of the neck and of the arm pain. Range of motion was determined by radiologic assessment of flexion-extension radiographs. Data were collected before surgery and at 6 weeks, 3, 6, 12, and 24 months after surgery. RESULT: A total of 125 patients were identified with 63 having TDR(43 males and 20 females) and 62 having fusion(42 males and 20 females). The average age was 49.1 years(TDR) and 51.7 years(ACDF)(p=0.229). The mean neck pain VAS before surgery was 6.52(TDR) and 6.61(ACDF)(p=0.732). At 2-year follow-up, the average neck pain VAS for the TDR group was 1.59 and ACDF 1.85(p=0.168). The mean arm pain VAS before surgery was 6.37(TDR) and 6.60(ACDF)(p=0.335). At 2 years: 1.41(TDR) and 1.65(ACDF)(P = 0.148). More motion(an average of 9.00 degrees at 24 months) was retained after surgery in the TDR group than the fusion group at the treatment level. There was no significant diffe- rence in motion at adjacent levels. CONCLUSION: Total disc replacement maintained physiological segmental motion at the 2-year follow-up. The finding that there was no statistically significant difference between the groups in motion at adjacent levels must be verified on further studies.

Cervical Intervertebral Disc Arthroplasty: Update

Since 1966 the first metal ball shape implant was inserted into the cervical and lumbar areas by Dr. Fernstrom, numerous attempts and prostheses have been tried to maintain physiologic range of motion and prevent adjacent segment degeneration (ASD) after surgery. However fusion itself is not a single causative factor of ASD and other biologic factors including natural progression of degenerative process and mechanical factors also contribute in the development of ASD. Several well designed prospective randomized control studies for Bryan disc and Prodisc C have been recently documented preservation of spinal motion, superior or, at least, equivalent clinical outcome in comparing with anterior cervical arthrodesis, and less adverse postoperative events both in frequency and severity. Still remained or undetermined problems in cervical arthroplasty are heterotopic ossifications, segmental kyphosis of implanted levels, MR imaging compatibility, vertebral body fracture by keeled prostheses and long term wear properties. In spite of these unsolved problems and incompleteness of prosthetic design, cervical arthroplasty is now considered as one of standard methods in surgical management of one or two level cervical disc diseases and its indication may be broader in near future.

Early Radiological Analysis of Cervical Arthroplasty with Bryan and Mobi-C Cervical Disc Prosthesis

OBJECTIVE: We investigated whether there are any different results in the overall sagittal alignment, neutral functional spine unit (FSU) angle and segmental FSU ROM (range of motion) angle from the patients undergone by cervical arthroplasty with two kinds of artificial cervical disc prostheses, Bryan and Mobi-C cervical disc. METHODS: Twenty eight patients underwent anterior cervical discectomy and implantation of artificial cervical disc prosthesis; Eighteen of them underwent operation with Bryan and the rest of them with Mobi-C cervical disc prosthesis. These patients consist of fourteen females and fourteen males with mean age 46.9 years old and 9.4 months mean follow-up period. There were 4 cases of C 4-5, 18 cases of C 5-6 and 6 cases of C 6-7 level. We measured overall sagittal alignment, neutral FSU angle and segmental FSU ROM angle using lateral radiographs preoperatively and postoperatively. The clinical outcome was evaluated by neck disability index(NDI). RESULT: The average angle of overall sagittal alignments was changed from -17.45degrees preoperatively to -14.21degrees postoperatively in Bryan cervical disc group. It decreased 3.24degrees in cervical lordosis. However, in Mobi-C cervical disc group, the average angle of overall sagittal alignments was changed from -10.33degrees preoperatively to -16.89degrees postoperatively. It increased 6.56degrees in cervical lordosis. The averages of neutral FSU angles were -1.14degrees preoperatively and -3.26degrees postoperatively in Bryan cervical disc group, and were -0.93degrees preoperatively and -9.7degrees postoperatively in Mobi-C cervical disc group. The averages of segmental FSU ROM angles were 11.18degrees preoperatively and 10.61degrees postoperatively in Bryan cervical disc group, and was 8.31degrees preoperatively and 13.6degrees postoperatively in Mobi-C cervical disc group. NDIs were 24.0 preoperatively and 5.9 postoperatively in Bryan cervical disc group, and 24.7 preoperatively and 8.7 postoperatively in Mobi-C cervical disc group. CONCLUSION: Postoperative cervical lordosis and segmental FSU ROM angle were increased in Mobi-C cervical disc group (p<0.05). To preserve segmental motion and avoid adjacent segment degeneration is to the focus in cervical arthroplasty. To preserve cervical lordosis after operation is physiologic than postoperative cervical kyphosis. It remains controversial whether cervical kyphosis influences clinical outcome after anterior cervical operation. The results of this study show that the technical and mechanical improvement of Bryan cervical disc prosthesis may be considered.

Clinical outcome of cervical arthroplasty in the treatment of spondylotic myelopathy / 中国矫形外科杂志

[Objective]To verify the clinical outcome of cervical arthroplasty in the treatment of spondylotlc myelopathy exclusively.[Method]From January 2004 to August 2003,twelve spondylotic myelopathy patients who underwent cervical arthroplasty were included in this study.Preoperative and final follow-up Nuriek grade,Oswestry neck disability index(ONDI)score,neck and arm pain VAS score of patients were recorded and compared.Surgical outcome was also measured using odom' s criteria.[Result]100% of patients had good or excellent outcomes using Odom' s criteria,while the final follow-up Nurick grade,ONDI score,neck and arm pain VAS score were improved significantly compared with the preoperative valule.[Conclusion]Cervical arthroplasty is effective in the treatment of spinal cord compression secondary to spondylotic disease with interveterbral movement being preserved.

Progress in artificial cervical disc replacement / 中华创伤骨科杂志

Although anterior cervical fusion has been a conventional surgical treatment for cervical spondylosis, concerns for the possible accelerated degeneration of adjacent segments after fusion have been growing. Fusion can also lead to other drawbacks, such as alteration of spinal biomechanics, graft and hardware complications, and chronic pain at the harvest site. In addition, it must be realized that decompression, not fusion, is the primary goal of anterior cervical surgery. Since the artificial cervical disc replacement can preserve enough motion after neural decompression with adequate stability, it provides a new surgical therapy for cervical spondylosis. This paper summarizes the progress in the related research field and makes comments on the current developments and future prospects of cervical arthroplasty.