Cervical Kinematics After Fusion and Bryan Disc Arthroplasty

Indiana Spine Group and Indiana University School of Medicine, Indianapolis, IN 46260, USA.
Journal of Spinal Disorders & Techniques (Impact Factor: 2.2). 02/2008; 21(1):19-22. DOI: 10.1097/BSD.0b013e3180500778
Source: PubMed


Disc arthroplasty has been shown to provide short-term clinical results that are comparable with those attained with traditional anterior cervical discectomy and fusion. One proposed benefit of arthroplasty is the ability to prevent or delay adjacent level operations by retaining motion at the target level and eliminating abnormal adjacent activity. This paper compares motion parameters for single-level anterior cervical discectomy and fusion and disc replacement patients at the index level and adjacent segments.
Radiographic data from patients enrolled in a prospective, randomized clinical trial were selected for kinematic assessment of cervical motion. All patients received either a single-level fusion with allograft and anterior cervical plate (Atlantis anterior cervical plate, n=13) or a single-level artificial cervical disc (Bryan Cervical Disc prosthesis, n=9) at either C5/C6 or C6/C7. Flexion, extension, and neutral lateral radiographs were obtained preoperatively, immediately postoperatively, and at regular intervals up to 24-month time points. Cervical vertebral bodies were tracked on the digital radiographs using quantitative motion analysis software (QMA, Medical Metrics) to calculate the functional spinal unit motion parameters including range of motion (ROM), translation, and center of rotation. If visible, the functional spinal unit parameters were obtained at the operative level, and also the level above and the level below.
As expected, significantly (P<0.006 at 3, 6, 12, and 24 mo) more flexion/extension motion was retained in the disc replacement group than the plated group at the index level. The disc replacement group retained an average of 6.7 degrees at 24 months. In contrast, the average ROM in the fusion group was 2.0 degrees at the 3-month follow-up and gradually decreased to 0.6 degrees at 24 months. The flexion/extension ROM both above and below the operative level was not statistically different for the disc-replaced and fusion patients, however, mobility increased for both groups over time. The anterior/posterior translation that occurs with flexion/extension motion remained unchanged for the disc replacement group at the level above the target disc preoperatively and postoperatively. In contrast, the translation increased for the level above the fusion. At the 6-month follow-up, the increase in translation was significantly greater for patients that were fused (P<0.02) than for patients that received a disc replacement. This change was not significant at 12 months.
Previous studies have shown the Bryan disc to maintain mobility at the level of the prosthesis. The long-term clinical benefit of maintenance of motion is postulated to be the ability to delay or avoid adjacent level operations. This study reveals that there is no difference in flexion/extension ROM at the level above and below either a fusion or Bryan arthroplasty. There is, however, an increase in anterior/posterior translation at the cephalad adjacent level in patients with arthrodesis while the Bryan arthroplasty retains normal translation for the same amount of flexion/extension at the adjacent level.
The Bryan disc may delay adjacent level degeneration by preserving preoperative kinematics at adjacent levels.

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    • "In 1958, Robinson, Smith [8] and Cloward [9] successively adopted ACDF to treat cervical spondylosis caused by intervertebral disc degeneration with good clinical effects, so it became the typical surgical method to treat cervical spondylosis. However, as is found in numerous long-term clinical cases, ACDF has some complications like reduced cervical activity and accelerated degeneration of adjacent-segment disc [10]. After as long as 21 years follow-up of 374 cases undergoing ACDF, Hilibrand et al. [11] found that the clinical syndromes caused by fusion adjacent segment degeneration had an average incidence of 2.9% in postoperative 10 years, which requires clinical focus and in-depth research. "
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    ABSTRACT: Background Anterior cervical discectomy and fusion (ACDF) was one of the preferred treatments for degenerative cervical spondylosis. However, the motion of adjacent segment was significantly increased after operation. So cervical disc arthroplasty have been suggested to keep the motion of adjacent segment. A new implant named dynamic cervical implant (DCI) has been developed to keep the motion of adjacent segment. Methods We retrospectively reviewed 91 patients treated for single level cervical spondylotic myelopathy with anterior cervical discectomy and fusion (ACDF), dynamic cervical implant (DCI) and cervical total disc replacement (CTDR) between sep 2009 and Mar 2011 in our hospital. They were divided into three groups by surgical methods: ACDF group (group A, 34 cases), DCI group (group B, 25 cases), CTDR group (group C, 32 cases). Operation time, intraoperative blood loss, preoperative and postoperative JOA score and JOA recovery rate were compared among the three groups. Pre-and postoperative hyperextension and hyperflexion radiograms were observed to measure range of motion (ROM) of C2–7, operative and adjacent levels. Results There was no statistical difference in operative time, intraoperative blood loss, and JOA recovery rate (P > 0.05) among three groups. But the differences of their postoperative JOA scores and preoperative JOA scores were of statistical significance (P < 0.05). Compared the pre-and postoperative ROM of C2–7, operative, upper and lower levels of each group respectively, the difference between preoperative ROM and postoperative ROM of group A were of statistically significant (P < 0.05), while was no statistically significant of group C (P > 0.05). There was no statistically significant difference between preoperative ROM and postoperative ROM of upper and lower levels in group B (P > 0.05), but had statistically significance of C2–7 and operative levels (P < 0.05). Conclusions Three operations are effective therapies for single level cervical spondylotic myelopathy. But each group has respective advantages and disadvantages.
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    Full-text · Article · Oct 2013 · International Journal of Biomedical Imaging
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    • "ACDR also resulted in markedly lower incidence of dysphonia compared to ACDF at two years post-operative followup . ACDR also prevents other complications of ACDF like pseudoarthrosis, side effects of cervical spine immobilisation and other implant related complication of anterior cervical plating [20]. "
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    ABSTRACT: Anterior Cervical Discectomy and Fusion (ACDF) currently remains as the gold standard treatment for cervical disc herniation and Degenerative Disc Disease (DDD) refractory to conservative management. Even though anterior cervical fusion provides excellent clinical results, it has been implicated in abnormal kinematic strain on adjacent disc level resulting in symptomatic adjacent segment disease. Anterior cervical disc replacement (ACDR) is an alternative procedure to anterior cervical discectomy and fusion. The aims of cervical disc replacement were to preserve the motion at the index level and to protect the adjacent levels from accelerated symptomatic degeneration. The aim of this systematic review was to evaluate the outcomes of cervical disc replacement published in MEDLINE indexed literature. A literature search was carried out in medical electronic database MEDLINE. Keywords used for the search were Cervical vertebrae , Cervical spine, Neck, Intervertebral disc, Total disc replacement, Arthroplasty, Replacement, Treatment outcome. Two authors reviewed titles and abstracts of all two hundred and thirty six hits. The articles that satisfied the inclusion criteria were critically appraised while remaining articles were discarded. Anterior cervical disc replacement is a relatively new technology in spinal surgery. There are several short and intermediate term follow-up studies to prove the safety and efficacy of ACDR with satisfactory clinical and radiological outcomes. More intermediate to long-term follow-up studies are needed to prove the safety and efficacy of ACDR.
    Full-text · Article · Jan 2013 · International Journal of Clinical Medicine
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