摘要目的:探讨椎间盘Pfirrmann退变评分对人工颈椎间盘置换（artificial cervical disc replacement, ACDR）术后异位骨化（heterotopic ossification, HO）量化的价值。方法:回顾性分析2009年1月至2016年12月接受ACDR手术并获2年以上随访的120例患者资料，男88例，女32例；年龄（43.86±8.69）岁（范围，27~67岁）；单节段置换100例（Hybrid手术9例），双节段置换20例（Hybrid手术3例）。颈椎侧位X线观察HO发生情况，McAfee等级标准评估HO严重度，Pfirrmann评分系统在术前MRI上评估椎间盘退变程度。加权Kappa检验分析Pfirrmann评分系统和McAfee分级系统不同观察者间的评价一致性， t检验比较HO组和非HO组术前椎间盘的Pfirrmann退变评分，卡方检验分析Pfirrmann评分对术后置换节段HO发生率的影响，Spearman秩和检验分析该评分与HO组McAfee等级、术后节段活动度（range of motion，ROM）的相关性。根据不同Pfirrmann评分组的置换节段HO发生率，提出ACDR手术的HO风险量化指标。 结果:120例患者随访（74.08±28.05）个月（范围，31~125个月）。术后2年根据病例数统计，38例患者颈椎出现HO，发生率为31.67%（38/120），单节段置换、双节段置换手术的HO发生率分别为27%（27/100）和55%（11/20）；根据置换节段数统计，HO组和非HO组分别包含46和94个置换节段。术前椎间盘Pfirrmann评分，HO组为（3.17±1.08）分较非HO组[（2.52±0.98）分]高25.80%，差异有统计学意义（ t=3.46， P=0.01）；置换节段HO发生率随术前Pfirrmann评分升高而显著升高（ χ2=12.44， P=0.01）；HO组术前椎间盘Pfirrmann评分与术后置换节段McAfee等级呈显著正相关（ R=0.54， P=0.01），与术后ROM呈显著负相关（ R=-0.75， P=0.01）。当椎间盘退变Pfirrmann评分<3、=3和>3时，术后2年置换节段HO发生率分别为20.55%（15/73）、38.46%（10/26）和51.22%（21/41）。 结论:颈椎间盘Pfirrmann退变评分与术后置换节段的HO发生率、McAfee等级以及ROM显著相关；颈椎间盘退变的Pfirrmann评分可作为ACDR手术HO风险的量化指标。

abstractsObjective:To explore the value of the Pfirrmann grading standard for disc degeneration in the quantification of heterotopic ossification (HO) after artificial cervical disc replacement (ACDR).Methods:Data of 120 patients who underwent ACDR from January 2009 to December 2016 were retrospectively analyzed. There were 88 males and 32 females with an average age of 43.86±8.69 (range, 27-67) years old. There were 100 single-level replacements (9 Hybrid cases) and 20 double-level replacements (3 Hybrid cases). The occurrence of HO was observed by lateral radiographs of the cervical spine. The HO severity was assessed using the McAfee rating system. Degeneration degrees of cervical intervertebral discs were evaluated by the Pfirrmann grading standard based on the preoperative cervical MRI. The weighted Kappa test was used to analyze the consistency of evaluations between different observers of the Pfirrmann scoring system and the McAfee grading system. Pfirrmann scores for preoperative disc degeneration in the HO and non-HO groups were compared using the t-test. The chi-square test was used to analyze the effect of the Pfirrmann score on the incidence of postoperative segmental HO. The correlation between Pfirrmann score and McAfee grade, as well as postoperative ROM of HO group were analyzed by the Spearman rank-sum test. Quantitative indicators for risks of HO after ACDR surgery were proposed based on the incidence of segment HO in different Pfirrmann score groups. Results:One hundred and twenty patients were followed up for an average of 74.08±28.05 (range, 31-125) months. Based on statistics of cases 2 years after surgery, the overall HO incidence was 31.67% (38/120). The HO incidence was 27% (27/100) and 55% (11/20) for single-level and double-level replacements, respectively. There were 46 replacement segments in the HO group and 94 replacement segments in the non-HO group. The Pfirrmann score of HO group (3.17±1.08) was 25.80% significantly higher than that of the non-HO group (2.52±0.98) ( t=3.46, P=0.01). The incidence of HO in the replacement segment increased significantly with the preoperative Pfirrmann score ( χ2=12.44, P=0.01). The Pfirrmann score of the intervertebral disc in the HO group had a significant positive correlation with the McAfee grade ( R=0.54, P=0.01) and a significant negative correlation with the ROM ( R=-0.75, P=0.01). At 2 years after the operation, when the Pfirrmann score of the intervertebral disc was less than 3, the incidence of HO in the replacement segment was 20.55%(15/73); when the Pfirrmann score was equal to 3, the incidence of HO was 38.46% (10/26); when the Pfirrmann score was greater than 3, HO incidence was 51.22% (21/41). Conclusion:The Pfirrmann score of cervical disc degeneration was significantly related to the incidence of HO, McAfee grade, and ROM in the postoperative replacement segment. The Pfirrmann score of cervical disc degeneration can be used as a quantitativeindicator of HO risk in ACDR.