人工颈椎间盘置换与颈前路减压融合术治疗脊髓型颈椎病的疗效比较

[目的]研究比较Bryan人工颈椎间盘置换术与经颈前路减压融合术治疗脊髓型颈椎病的临床疗效.[方法]回顾性分析2004年1月～2008年1月收治的57例颈椎病手术的病例,其中19例行人工颈椎间盘置换术,38例行颈前路减压融合术.[结果]置换组术后颈部生理活动度得到保持,JOA评分由9.6±3.5升至14.3±4.6(6个月)、16.1±3.2(3年),Odom评定满意率100%;融合组术后颈部活动由48.6°±6.1°降至36.6°±3.5°(单节段融合)和48.4°±4.1°降至27.3°±5.3°(双节段融合),Odom评定满意率97.3%.[结论]人工颈椎间盘置换术与颈前路减压融合术治疗脊髓型颈椎病早、中期疗效满意,前者不加速相邻节段的退变,显著减少由融合导致的多种并发症.     

颈椎间盘置换治疗颈椎病术后相邻节段退变的临床观察

[目的]观察颈椎间盘置换治疗颈椎病术后相邻节段退变的临床疗效。[方法]采用随机分配法将2010年7月~2013年7月来本院进行治疗的80例患者随机分为两组,置换组采用颈椎间盘置换术进行治疗,融合组采用前路颈椎间盘切除融合术,术后在不同时间对两组患者进行随访,分析两组患者术后相邻节段退变情况。[结果]置换组患者的JOA评分较术前相比平均提高了5.33分,与融合组的5.27分比较差异无统计学意义;对邻近节段颈椎间盘的退变情况分析,得出在最后一次随访时即术后24个月时,置换组有7例出现退变,退变率为17.5%,融合组有14例出现退变,退变率为35.0%,两组均无死亡患者。[结论]颈椎间盘置换治疗颈椎病在具有良好疗效的同时,降低了相邻节段的退变率,值得在临床上推广应用。     

颈椎人工椎间盘置换疗效评价

1 颈椎人工椎间盘的背景 颈前路减压植骨融合术(anterior cervical decompression and fusion,ACDF)是治疗颈椎病等颈椎退行性疾病的传统手段,自其广泛应用于临床以来,取得了很好的临床疗效,长期随访发现ACDF术后融合率可达到73%～90%,并且能明显缓解患者的症状 [1、2].但刚性融合会导致邻近节段活动度和应力的代偿性增加,从而引起或加速邻近节段退变,进而引起原有症状的加重或复发 [3～5].Hillibrand等 [6]随访21年409例颈椎前路减压融合术患者发现,邻近节段新发病的发生率约为2.9%,在手术后10年内大约有近1/4的患者出现邻近节段新发病而需行再次颈椎手术治疗.为解决异常应力作用于融合邻近节段的问题,颈椎人工椎间盘置换术应运而生,它可以维持颈椎的正常生理性活动度及稳定性,改善邻近椎间隙的压力,并能减少正常颈托制动时间,使患者早期恢复正常工作生活,而且可以减少邻近节段退变的发生.与ACDF相比,人工颈椎间盘置换术恢复或重建了颈椎的生理功能,无疑是治疗颈椎病更加理想的手术方式.常见的颈椎人工椎间盘包括Bryan、Cervitech PCM(porous coated motion)、Pro-disc-C等.     

颈人工椎间盘置换术治疗颈椎病的临床研究

目的 探讨Bryan颈人工椎间盘假体置换术治疗颈椎病的临床疗效,同时与颈前路减压植骨融合术相比较,观察两种术式的近期临床疗效.方法 脊髓型和神经根型颈椎病患者共48例,21例（22个节段）行颈前路颈人工椎间盘假体置换术（置换组）,27例（32个节段）采用颈前路减压植骨融合术（融合组）.两组患者分别在术前,术后,术后3、6、12、18个月观察以下指标：JOA评分;摄颈椎前屈后伸位、左右侧屈位X线片,观察置换组的假体稳定性和植入节段及上下临近节段的活动度,观察融合组融合节段的上下临近节段的关节活动度;MRI或CT扫描检查颈人工椎间盘假体位置及有无异位骨化现象.结果 两组术后临床症状缓解,脊髓功能改善,均无并发症.两组JOA评分比较：术后各时间段较术前明显提高（P＜0.01）,两组术后各时间段之间的评分比较无显著差异.术后各时间段随访摄X线片显示：置换组置换节段较术前保留了部分关节活动度,上下临近关节活动度未显著增加,未发现假体偏移或下沉;而融合组临近节段活动度显著高于置换组（P＜0.01）.术后CT或MRI扫描显示：置换组假体位于临近上、下终板骨的中央,未见假体周围异位骨化现象;融合组出现1例下临近节段退变压迫脊髓.结论 与颈前路减压植骨融合术比较,颈人工椎间盘置换术既能良好地达到前路减压目的,又能保持颈椎病变节段的部分活动度和稳定性,且未显著增加上下临近节段活动度,取得了较好的近期临床疗效.     

人工颈椎间盘置换与颈前路融合术治疗脊髓型颈椎病3年随访结果报道

[目的]比较人工颈椎间盘置换与颈前路减压植骨融合术治疗脊髓型颈椎病的3年随访结果。[方法]回顾性分析2004年11月²009年3月在本院接受手术治疗,并完成3年随访的65例脊髓型颈椎病患者。31例行人工颈椎间盘置换术,其中单节段置换26例,双节段置换5例,13例14个节段应用Bryan假体,18例22个节段应用Prestige LP假体,34例行颈前路减压植骨融合术,其中单节段融合28例,椎体次全切双节段融合6例。分别在术前,术后1周,术后12、24及36个月对患者进行SF-36生活质量量表、JOA评分、NDI评分、Nurick分级的评估,术后36个月采用Odom’s标准评价临床效果;在各随访时点采用颈椎正侧位X线片观察置入物的稳定性,并采用动力位X线片测量手术节段屈伸活动度;同时记录患者术中、术后并发症及二次手术的发生情况。[结果]两组患者的JOA评分、Nurick分级术后各随访时点较术前比较均有明显改善(P<0.05),两组之间差异无统计学意义(P>0.05),两组患者SF-36躯体评分及心理评分、NDI评分术后各随访时点较术前有明显改善(P<0.05),两组间比较,置换组优于融合组(P<0.05)。术后各随访时点置换组手术节段屈伸活动度维持在术前水平(P>0.05),而融合组手术节段屈伸活动度较术前明显下降(P<0.05)。置换组中2例患者发生假体前移,2例发生轻度异位骨化,1例因脑脊液漏接受二次手术。融合组中1例患者发生了假关节形成,6例存在供骨区的疼痛,3例因邻近节段退变接受二次手术。[结论]人工颈椎间盘置换术与颈前路减压植骨融合术治疗脊髓型颈椎病3年随访疗效均满意,且前者保留了手术节段运动功能,减少了融合导致的多种并发症。     

颈椎前路减压人工颈椎间盘置换术与融合术治疗单节段颈椎间盘突出症的短期疗效比较

背景：颈前路椎间盘切除植骨融合术（ACDF）能够为有症状的颈椎病患者提供较好的治疗效果,但颈椎融合可导致相邻节段椎间盘内部应力增加,加速邻近节段椎间盘的退变。颈椎人工椎间盘置换术（ACDR）作为最具代表性的颈椎前路非融合技术,为颈椎间盘突出症的治疗提供了另外一种外科手段。目的：比较ACDR和ACDF治疗单节段颈椎间盘突出症的临床效果。方法：2009年1月至2012年2月,61例单节段颈椎间盘突出症患者接受Discover人工颈椎间盘置换手术（置换组,26例）或ACDF手术（融合组,35例）。分别在术前,术后1周,术后3、6、12及24个月对患者进行疼痛视觉模拟评分（VAS）、日本矫形外科协会（JOA）评分及影像学评估,同时记录患者并发症及二次手术情况。结果：最终,52例患者（融合组29例,置换组23例）获得平均15.3个月（12-24个月）随访。两组患者术后各随访时间点的颈痛、上肢痛VAS和JOA评分,较术前均有改善（P〈0.05）,但两组间无显著统计学差异（P〉0.05）。置换组术后手术节段及邻近节段屈伸活动度与术前比较无统计学差异（P〉0.05）。融合组融合成功率为90.5%。置换组中2例患者术后6个月时假体有〈3 mm的前移,l例术后发生脑脊液漏。融合组中1例患者发生邻椎病并接受二次手术治疗。结论：单节段Discover人工颈椎间盘置换术和ACDF均可明显缓解颈椎间盘突出症患者的症状。间盘置换还能减少手术邻近节段代偿活动度的增加,有望预防相邻节段退变的发生。     

人工颈椎间盘置换术后邻近节段退变情况的早中期随访

目的研究人工颈椎间盘置换术治疗颈椎病的临床疗效及邻近节段退变情况。方法 2008年1月-2010年10月,采用人工颈椎间盘置换术治疗颈椎病患者39例。其中男20例,女19例;年龄32～60岁,平均45.7岁。病程1个月～10年,平均30个月。其中脊髓型颈椎病26例,神经根型颈椎病11例,混合型颈椎病2例(神经根型加脊髓型)。单节段病变27例,双节段病变12例。使用Prestige假体9例、Prodisc-C假体4例、Discover假体26例。采用日本骨科协会(JOA)评分评价患者神经功能恢复情况,测量置换节段及邻近节段活动度(Cobb角变化),并采用Kellgren X线颈椎退变分级评估法对邻近节段颈椎间盘退变情况进行评价。结果所有患者均顺利完成手术,术后切口均Ⅰ期愈合。39例均获随访,随访时间12～36个月,平均23.1个月。末次随访时患者JOA评分较术前显著提高(P<0.05),置换节段及置换节段相邻上、下位节段活动度与术前比较差异均无统计学意义(P>0.05)。根据Kellgren X线椎间盘退变分级评价结果显示,末次随访时有5例患者出现退变情况改变,其中从无(0级)退变为轻度(1、2级)3例,由轻度1级退变到轻度2级1例,由轻度2级退变到中度(3级)1例,退变发生率为12.8%,但退变情况分级与术前比较差异无统计学意义(χ2=1.793,P=0.406)。术后15个月(32例患者)邻近椎间盘未发生退变情况。结论人工颈椎间盘置换术治疗颈椎病有良好疗效,可较好地保留置换节段及邻近节段活动度,并可能对邻近节段的椎间盘起保护作用。     

人工颈椎间盘置换术在后纵韧带骨化症中的应用

[目的]观察应用Bryan颈椎间盘假体置换术治疗后纵韧带骨化症的近期效果。[方法]2005年10月～2007年6月应用Bryan人工颈椎间盘假体置换术治疗局限型后纵韧带骨化症患者15例,术前和术后6个月时进行JOA评分,并摄颈椎前屈后伸位X线片,观察假体稳定性及颈椎置换节段的活动度。[结果]患者术后症状均明显缓解,随访6～24个月,JOA评分由术前平均8.5分上升至术后平均15.8分。置换节段保留了运动功能,假体稳定无移位。[结论]人工颈椎间盘置换术近期可保持前路减压的良好效果,同时可获得术后即刻稳定性。维持颈椎近正常的活动度。人工颈椎间盘置换术是治疗局限型后纵韧带骨化症的一种有效方法。     

人工颈椎间盘置换术的研究进展

前路融合术是目前治疗颈椎病的常规术式,但颈椎前路融合术后邻近节段的退变加速越来越受到人们的重视。融合术还引起脊柱的生物力学改变,且存在植骨和内固定器械的并发症及供骨区慢性疼痛等。此外,颈椎前路手术的主要目标是解除脊髓的压迫而不是融合,这些都是困扰脊柱外科医师的难题。人工颈椎间盘置换术可在进行脊髓减压并提供稳定的同时保持手术节段颈椎的活动度,为颈椎病的外科治疗开辟了新的途径。本文结合最新文献对该技术的发展和前景进行综述。     

颈前路人工颈椎间盘置换术与Zero-p椎间植骨融合内固定治疗双节段脊髓型颈椎病的疗效比较

目的比较颈前路人工颈椎间盘置换术和Zero-p椎间植骨融合内固定治疗双节段脊髓型颈椎病的临床疗效。方法回顾性分析自2014-05—2019-05诊治的55例双节段脊髓型颈椎病,26例采用颈前路人工椎间盘置换术治疗(观察组),29例采用Zero-p椎间植骨融合内固定治疗(对照组)。比较2组手术时间、术中出血量、术后引流量、邻近节段退变数,比较2组末次随访时疼痛VAS评分、JOA评分、NDI指数、伤椎Cobb角、C_(2～7)活动度、C_(2～7)颈椎曲度、手术节段活动度、上位相邻节段活动度、下位相邻节段活动度。结果 2组均顺利完成手术并获得至少24个月的随访。2组手术时间、术中出血量、术后引流量比较差异无统计学意义(P0.05)。观察组术后出现邻近节段退变数较对照组少,差异有统计学意义(P0.05)。末次随访时2组疼痛VAS评分、JOA评分、NDI指数、伤椎Cobb角比较差异无统计学意义(P0.05),观察组C_(2～7)活动度、C_(2～7)颈椎曲度、手术节段活动度、上位相邻节段活动度、下位相邻节段活动度较对照组大,差异有统计学意义(P0.05)。结论颈前路人工颈椎间盘置换术和Zero-p椎间植骨融合内固定治疗双节段脊髓型颈椎病均能改善脊髓功能,增加颈椎活动度,颈前路人工颈椎间盘置换术在维持颈椎活动度、减少术后相邻节段退变等方面有一定优势。     

Design limitations of Bryan disc arthroplasty.

BACKGROUND CONTEXT: Disc arthroplasty is gaining momentum as a surgical procedure in the treatment of spinal degenerative disease. Results must be carefully scrutinized to recognize benefits as well as limitations. PURPOSE: The aim of this study was to investigate factors associated with segmental kyphosis after Bryan disc replacement. STUDY DESIGN/SETTING: Prospective study of a consecutively enrolled cohort of 10 patients treated in a single center using the Bryan cervical disc prosthesis for single-level segmental reconstruction in the surgical treatment of cervical radiculopathy and/or myelopathy. Radiographic and quality of life outcome measures. METHODS: Static and dynamic lateral radiographs were digitally analyzed in patients undergoing Bryan disc arthroplasty throughout a minimum 3-month follow-up period. Observations were compared with preoperative studies looking for predictive factors of postoperative spinal alignment. RESULTS: Postoperative end plate angles through the Bryan disc in the neutral position were kyphotic in 9 of 10 patients. Compared with preoperative end plate angulation there was a mean change of -7 degrees (towards kyphosis) in postoperative end plate alignment (p=.007, 95% confidence interval [CI] -6 degrees to -13 degrees). This correlated significantly with postoperative reduction in posterior vertebral body height of the caudal segment (p=.011, r2=.575) and postoperative functional spine unit (FSU) kyphosis (p=.032, r2=.46). Despite intraoperative distraction, postoperative FSU height was significantly reduced, on average by 1.7 mm (p=.040, 95% CI 0.5-2.8 mm). CONCLUSIONS: Asymmetrical end plate preparation occurs because of suboptimal coordinates to which the milling jig is referenced. Although segmental motion is preserved, Bryan disc arthroplasty demonstrates a propensity towards kyphotic orientation through the prosthesis likely as a result of intraoperative lordotic distraction. FSU angulation tends towards kyphosis and FSU height is decreased in the postoperative state from lack of anterior column support. Limitations of Bryan cervical disc arthroplasty should be carefully considered when reconstruction or maintenance of cervical lordosis is desirable.     

Bryan颈椎间盘假体置换治疗硬膜外型颈椎间盘突出症

目的探讨Bryan人工颈椎间盘置换应用于硬膜外型颈椎间盘突出症的手术技巧并评价其近期临床疗效。方法2005年2月~2005年12月,对5例硬膜外型颈椎间盘突出症患者实施前路减压 Bryan颈椎间盘假体置换术。术前摄颈椎正、侧位和动力位X线片,颈椎CT、MRI并进行颈椎病JOA评分。术后1周复查颈椎X线片以了解假体位置及其活动功能情况;复查颈椎MRI,了解颈段脊髓减压情况。本组病例均获随访3~13个月(平均7个月),分别于术后6周、3个月重新进行JOA评分。结果本组患者均完成单节段椎间盘置换,术后无神经、血管损伤等并发症发生;颈椎MRI示所有患者颈脊髓减压彻底,术后临床症状均显著改善;术后6周及3个月的JOA评分较术前有明显提高。至最后一次随访复查,手术节段活动度无明显丢失,假体均无偏移、下沉等。结论对硬膜外型颈椎间盘突出症行Bryan颈椎间盘假体置换术时,在满足假体骨床的前提下,仍可获得充分的颈脊髓减压。     

Bryan人工颈椎椎间盘置换术后中长期临床疗效及相关问题分析

目的探讨Bryan人工颈椎椎间盘置换术（artificial cervical disc replacement,ACDR）治疗颈椎椎间盘突出症的中长期临床疗效及并发症发生情况。方法回顾分析13例颈椎椎间盘突出症患者,采用Bryan ACDR治疗,单节段11例,双节段2例,共置换了15个节段。术后定期随访,依照Odom评级和日本骨科学会（Japanese Orthopaedic Association,JOA）评分评定临床疗效和神经功能改善情况,通过影像学资料观察假体位移、假体周围骨吸收、异位骨化、假体活动度及颈椎生理曲度变化。结果经过5年以上的随访,患者神经症状有明显缓解,Odom评级临床优良率达到92.3%J,OA评分由术前的11.6分增加到的15.6分。术后X线片示假体稳定,没有出现假体前后位移〉2 mm。术后1例出现自发性融合;1例在置换节段上位椎体前下缘有明显骨吸收,接近2.5 mm,并伴椎体后缘的异位骨化。末次随访时置换假体活动度平均为9.2°,邻近节段活动度与术前相当。结论通过5～7年的中长期随访,Bryan ACDR术治疗颈椎椎间盘突出症具有较好的临床疗效,并发症少,安全可靠。     

人工颈椎间盘假体置换治疗颈椎病的早期临床研究

目的探讨初期应用人工颈椎间盘假体治疗颈椎病的疗效。方法应用Bryan人工椎间盘假体置换治疗脊髓型颈椎病和神经根型颈椎病患者18例（22个节断），术前、术后进行JOA评分比较评价早期治疗效果；术后摄置换节段前屈后伸位，左右侧屈位X线片，观察稳定性和植入节段的活动度。结果随访16～36个月，平均20个月。无伤口感染及假体脱位病例，患者JOA评分由术前平均9．0（7～11）分上升至术后平均15．0（13～17）分，术后3个月置换节段前屈后伸活动范围平均4．8°（4．1°～5．5°），左右侧屈活动范围分别为3．7°（3．4°～4．0°）和3．6°（3．3°～3．9°）。X线片显示颈椎稳定性好，运动功能无明显丢失。结论应用人工颈椎间盘假体置换治疗颈椎间盘疾病早期效果良好。     

Bryan人工颈椎间盘置换术治疗颈椎病的中期疗效观察

摘要：目的观察Bryan人工颈椎间盘置换术治疗颈椎病的中期疗效。方法2005年11月至2010年5月对16例颈椎病患者行Bryan人工颈椎间盘置换术。统计并分析患者术前、术后及末次随访时的JOA评分、置换节段活动度,观察术后及末次随访时假体松动、移位、异位骨化等并发症。结果16例患者均获得随访,随访时间为12—53个月,平均24．1个月,JOA评分由术前平均（10．4±1．9）分增至术后平均（14．4±1．9）分以及末次随访平均（16．1±0．7）分,术前与术后（t=-12．215,P=0．000）、术后与末次随访（t=-4．273,P=0．001）均有显著性差异。12例患者随访时行颈椎屈伸位x线片检查,随访时间13—53月,平均24．2月,测量屈伸位X线片计算置换节段颈椎屈伸活动度（rangeofmotion,ROM）,术前平均7．1°±2．6°、术后平均6．9°±1．9°、末次随访平均6．5°±1．8°,术前与术后（t=0．700,P=0．395）、术后与末次随访（t=2．132,P=0．054）均无统计学差异。无一例发生异位骨化;1例随访时出现假体周围骨吸收。结论Bryan人工颈椎间盘置换术治疗颈椎病的中期疗效满意,但仍需长时间随访以评估其远期疗效。     

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.     

颈椎人工椎间盘置换早期临床报道

目的探讨初期应用Bryan人工椎间盘系统治疗颈椎病的疗效。方法2003年12月~2005年2月应用Bryan人工椎间盘系统治疗脊髓型颈椎病和神经根型颈椎病患者17例。结果随访5~15个月,平均10个月。无伤口感染病例,患者神经系统症状均有不同程度的改善,颈椎活动大部分接近正常。有1例术后3个月发现假体有轻度位移,但不超过2mm且没有明显的症状。JOA评分由术前平均8.5分提高到术后的15分,平均改善率为75%。术后1个月、3个月和6个月分别门诊随访时,拍摄颈椎正侧位和过屈过伸侧位X线片显示颈椎稳定性好,运动功能无明显丢失。未见假体周围异位骨化。结论人工颈椎间盘置换为颈椎病的治疗提供了一个新的选择。     

Bryan人工颈椎间盘置换对颈椎功能影响的临床分析

目的 探讨Bryan人工颈椎间盘置换手术对颈椎功能的影响.方法 对2003年12月至2007年8月施行的164例患者200个椎间盘的人工颈椎间盘置换手术进行回顾性分析.164例患者中,男性102例,女性62例,年龄25～70岁,平均47岁;单间隙置换132例,双间隙置换28例,三间隙置换4例.均采用Bryan人工颈椎间盘假体.手术严格按照Bryan人工颈椎间盘假体植入的标准操作程序进行.术后颈托外固定2周.结果 随访时间2～44个月,平均26个月.JOA评分改善率56%.椎间活动度:矢状位术前平均活动度14.4°,术后1周5.7°,末次随访时平均14.7°,与手术前相比差异无统计学意义.邻近间隙矢状位术前平均活动度10.9°,术后1周5.5°,末次随访时平均8.2°,主要是由上邻接间隙的活动度没有达到术前水平所致.患者满意度94%.1例患者术后6个月假体松动,以后稳定;1例患者术后7个月假体发生1 mm下沉,以后稳定;3例后方融合.无前方融合、食管损伤、喉返神经损伤以及再手术病例.手术操作单间隙平均90 min,双间隙平均130 min.结论 人工颈椎间盘置换手术临床疗效良好.     

Cervical kinematics after fusion and bryan disc arthroplasty

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. DISCUSSION: 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. CONCLUSION: The Bryan disc may delay adjacent level degeneration by preserving preoperative kinematics at adjacent levels.