假体张口角度变化对颈椎间盘置换术后异位骨化影响的临床研究

Influence of the change of prosthesis open angle on heterotopic ossification after cervical disc arthroplasty

目的:分析术后即刻植入假体张口角度变化对人工颈椎间盘置换(CDA)术后异位骨化(HO)的影响,为预防或减少术后HO、维持假体的长期有效活动而在植入技术的改进上提供理论依据。方法:回顾性分析单节段Prestige-LP CDA且临床和影像学随访至少3年的95例病例。HO评价采用McAfee HO分级系统。评价的影像学参数包括目的节段椎间隙角(DSA)、节段活动度(SROM)、假体前后移位和下沉及假体-终板覆盖率。临床功能评分包括疼痛视觉模拟评分、颈部功能障碍指数和日本骨科协会评分。分析术后即刻DSA(假体张口角)相对于术前的变化(△DSA)对HO形成的影响,并评价术后即刻假体张口角度变化对HO重要危险因素和临床效果的影响。结果:术后即刻假体张口后凸增加病例(△DSA≤-2°)中HO的发生率及程度均显著高于假体张口前凸增加的病例(△DSA>-2°,P<0.05);假体张口后凸增加病例末次随访SROM也显著低于假体张口前凸增加的病例(P<0.05)。在△DSA>-2°的病例中,△DSA与HO的发生也存在明显的关联(P<0.05);术后即刻张口前凸增加大于5°病例中HO发生率及程度均显著高于张口前凸增加小于5°的病例(P<0.05);临床功能评分与术后即刻DSA的增加程度或HO的发生无显著关联;与张口前凸增加小于5°的病例相比,张口前凸增加大于5°的病例呈现出更大的假体前移位、更低的假体-终板覆盖率(P<0.05),以及比术前更低的SROM(P<0.05)。结论:对假体张口角度的过度改变与CDA术后HO的发生和发展有关,通过与椎间隙相对平行的终板准备而适当地维持假体张口变化可能是预防或减少HO形成和保障CDA术后长期疗效的重要因素。

Objective:To analyze the influence of the immediate postoperative change of the implanted prosthesis open angle on heterotopic ossification(HO) after cervical disc arthroplasty(CDA),and to explore and provide theoretical basis for the improvement of surgical techniques to prevent or reduce postoperative HO and maintain the long-term clinical efficacy of CDA.Methods:Totally 95 patients with single-level Prestige-LP arthroplasty were retrospectively reviewed.All patients were followed up clinically and radiographically for a minimum of 3 years.HO was assessed based on McAfee classification.Radiological parameters including target disc space angle(DSA),segmental range of motion(SROM),anteroposterior migration and subsidence of the prosthesis and prosthesis-endplate coverage ratio were evaluated.Clinical outcome scores including visual analogue scale,neck disability index and Japanese Or-thopaedic Association were also evaluated.The effects of the immediate postoperative changes in DSA relative to preoperation(ΔDSA) on the formation of HO after CDA were analyzed,and the effects of the extent of maintaining immediate postoperative DSA lordosis(prosthesis open angle) on important risk factors for HO and clinical outcomes were explored.Results:The incidence and extent of HO after CDA in patients with a immediate postoperative DSA kyphosis increase(ΔDSA≤-2°) were significantly higher than those with a DSA lordosis maintained or increased immediately after surgery(ΔDSA>-2°,P<0.05),and the SROM of the former at the final follow-up was significantly lower than that of the latter(P<0.05).In the patients with ΔDSA>-2°,a significant association between immediate postoperative DSA change and HO occurrence was also found(P<0.05);the incidence and extent of HO in patients with a more than 5°increase of immediate postoperative DSA lordosis were significantly higher than that of HO in patients with a less than 50 DSA increase after CD A(P<0.05);no correlation was observed between clinical outcomes and postoperative DSA increase or HO occurrence;patients with a more than 5° DSA increase exhibited larger anterior migration amount and lower prosthesis-endplate coverage ratio compared with patietns with a less than 5° increase in DSA(P<0.05),and less SROM at the final followup compared with those at pre-operation(P<0.05).Conclusions:Excessive changes in the prosthesis open angle in artificial cervical disc implantation may be associated with the occurrence and development of HO after CDA,and appropriately correcting DSA through endplate preparation relatively parallel to the disc space may be the more important factor for preventing or reducing HO formation and maintaining the long-term efficacy after CDA.