Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Beitou, Taipei, Taiwan.
J Neurosurg Spine. 2011 Apr;14(4):457-65. doi: 10.3171/2010.11.SPINE10444. Epub 2011 Feb 4.
Heterotopic ossification (HO) after cervical total disc replacement (TDR) has been reported to impede artificial disc motion. In all previously reported cases of HO, assessment was based on plain radiographs. The authors hypothesized that CT scan is a more sensitive and accurate detector. The aims of this study were to assess the actual incidence of HO and its effect on outcome in a cohort of patients undergoing cervical TDR with the Bryan disc and to compare HO detection by means of plain radiographs and CT.
The authors retrospectively assessed data from medical records, radiological studies, and clinical evaluations of patients who underwent 1- or 2-level cervical TDR with the Bryan disc and were followed up for more than 12 months. The presence and grading of HO according to the McAfee classification were assessed by CT scan, and these findings were compared with findings on plain radiographs. Thirty-six patients (mean age 46.61 ± 7.24 years; range 29-60 years; 21 men and 15 women) who underwent Bryan TDR at 52 levels were included in the study. The mean duration of CT follow-up was 19.03 ± 4.64 months; the mean duration of clinical follow-up was 26.78 ± 7.20 months.
On the basis of CT, HO was identified in 18 (50%) of 36 patients and 25 (48.1%) of 52 levels treated. Grade 1 HO was present in 9 of the levels treated (17.3%), Grade 2 in 13 levels (25.0%), Grade 3 in 2 levels (3.8%), and Grade 4 in 1 level (1.9%). Nineteen (76%) of the 25 affected levels were in patients who had undergone 2-level TDR. There was no significant association with patient sex or disc pathology. There was a tendency for HO development among older patients, but this finding was not statistically significant (mean age 48.8 ± 6.8 in patients with HO vs 44.4 ± 7.2 in those without HO, p = 0.065). Although HO was found in 25 levels, 96.2% of the treated levels (50 of 52) had segmental range of motion on dynamic (flexion and extension) radiographs. The concordance between HO grading by CT and radiography was high, with an intraclass correlation coefficient of 0.822 (lower limit of 95% CI: 0.710, p < 0.001). Patients who had HO had the same clinical success rate as those who did not (94.4% vs 94.4%, p = 1.00). The visual analog scale scores for neck and arm pain were significantly improved in both the HO and the non-HO group.
The rate of HO detected by CT scan in this cohort of patients undergoing cervical TDR with a Bryan disc was 48.1% per level treated and 50% per patient with minimal limitation of segmental motion (96.2% of levels remained mobile), but plain radiograph is an acceptable detection tool. Two-level surgery has a higher risk of HO, although development of HO does not affect clinical outcome.
颈椎全椎间盘置换（TDR）后异位骨化（HO）已被报道会阻碍人工椎间盘运动。在所有先前报道的 HO 病例中，评估均基于普通 X 射线。作者假设 CT 扫描是一种更敏感和准确的检测方法。本研究的目的是评估 Bryan 椎间盘颈椎 TDR 患者队列中 HO 的实际发生率及其对结局的影响，并比较普通 X 射线和 CT 对 HO 的检测。
作者回顾性评估了接受 Bryan 椎间盘 1 或 2 节段颈椎 TDR 且随访超过 12 个月的患者的病历、影像学研究和临床评估数据。通过 CT 扫描评估 HO 的存在和 McAfee 分级，并将这些发现与普通 X 射线检查的结果进行比较。本研究纳入了 36 例（平均年龄 46.61 ± 7.24 岁；年龄 29-60 岁；21 名男性和 15 名女性）接受 Bryan TDR 的患者共 52 个节段。CT 随访的平均持续时间为 19.03 ± 4.64 个月；临床随访的平均持续时间为 26.78 ± 7.20 个月。
根据 CT，36 例患者中的 18 例（50%）和 52 个治疗节段中的 25 个（48.1%）发现有 HO。治疗节段中，1 级 HO 为 9 个（17.3%），2 级为 13 个（25.0%），3 级为 2 个（3.8%），4 级为 1 个（1.9%）。25 个受影响的节段中有 19 个（76%）是在接受 2 节段 TDR 的患者中发现的。HO 的发生与患者性别或椎间盘病变无关。HO 发展与患者年龄有一定相关性，但无统计学意义（HO 患者的平均年龄为 48.8 ± 6.8 岁，无 HO 患者为 44.4 ± 7.2 岁，p = 0.065）。尽管在 25 个节段中发现了 HO，但在动态（屈伸）X 射线片上，52 个治疗节段中有 96.2%（50 个）仍具有节段活动度。CT 和 X 射线 HO 分级之间的一致性较高，组内相关系数为 0.822（95%CI 的下限：0.710，p < 0.001）。有 HO 的患者与无 HO 的患者临床成功率相同（94.4%比 94.4%，p = 1.00）。HO 组和非 HO 组的颈痛和臂痛视觉模拟评分均显著改善。
在接受 Bryan 椎间盘颈椎 TDR 的患者队列中，CT 扫描检测到的 HO 发生率为每治疗节段 48.1%，每例患者 50%，节段运动受限最小（96.2%的节段仍保持活动），但普通 X 射线是一种可接受的检测方法。虽然 HO 的发生并不影响临床结局，但二节段手术的 HO 风险更高。
