| Objective: Since anterior cervical discectomy and fusion(ACDF) was first introduced by Smith and Robinson, it has been the standard of care for cervical degenerative disease. However, arthrodesis of the spinal segments may lead to excessive stress at the unfused adjacent levels, and many studies have reported adjacent-level degenerative changes in 25–89% of patients after cervical arthrodesis. The reported risk factors related to the development of adjacent segment degeneration are the number of fusion segments, the fusion level, age of the patient, combined underlying conditions, and previous degeneration. Eventually, this condition leads to adjacent segment disease(ASDz), which presents with new symptoms of radiculopathy or myelopathy.Currently, various fusion materials and additional plate augmentations are widely used for anterior cervical arthrodesis. However, previous reports are limited and most studies have analyzed the results of anterior fusion using autografts only. We performed this study to determine the risk factors for ASDz by analyzing patients with anterior cervical arthrodesis treated with two fusion methods for degenerative cervical disease.Method: We enrolled 200 patients who had undergone anterior cervical fusion for degenerative cervical disease and had at least 5 years of follow-up in this retrospective study, from February 2002- January 2010. There were treated in our department and eventually completed the follow-up. The study population consisted of 112 men and 88 women. According to the different fusion methods of anterior cervical surgery is divided into A, B two groups.Patients in Group A received autogenous bone graft only, including 83 cases,47 males and 36 females, the average patient age at the time of surgery was58.51years±7.56 years and the average follow-up period was71.5months±7.7months. Patients in Group B underwent cage and plate augmentation, including 117 cases, 65 males and 52 females, the average patient age at the time of surgery was 57.74years±7.83 years and the average follow-up period was 73.6months±7.2months. Careful physical and radiological examination, including plain radiography and MRI, were performed pre-operatively in all patients. Radiographic data were evaluated at6 weeks and at 3, 6,9, 12, and 18 months post-operatively and then annually by using anterior-posterior, lateral, and flexion/extension lateral plain radiographs. MRI was performed for evaluation in patients who presented with additional radiculopathy or myelopathic symptoms during follow-up.The new diagnoses, time of onset of radiculopathy or myelopathy after the initial surgery, treatment methods, and clinical results. We analyzed the development of ASDz and the rate of revision surgery due to ASDz. To identify the risk factors for ASD, the sagittal alignment, range of motion(ROM) of the cervical spine, and the fusion method were evaluated and compared between ASDz and disease-free patients.Results: We noted ASDz in 40 patients(20.00%), of whom 9 patients(4.50%) were surgically treated. The mean duration for the development of ASDz was 62.9months ± 5.9months. Twenty-nine men(25.9%) and eleven women(12.5%) developed ASDz. The rate of development of ASDz was significantly higher in male patients(P<0.05). The mean cervical ROM was35.43°(29.80°,43.99°)in the ASDz patients and 22.11°(18.25°,33.55°)in disease-free patients. The ROM in the two groups was significantly different(P<0.05). The post-operative sagittal alignment was 17.02°(13.74°,19.98°)in the ASDz group and 19.87°(15.29°,23.56°)in the disease-free group. The post-operative sagittal alignment in the two groups was significantly different(P<0.05). In the Group A, we noted ASDz in 33 patients(39.8%), of whom 7 patients(8.4%) were surgically treated. The mean duration for the development of ASDz was 61.6months ± 5.5months. In the Group B, we noted ASDz in 7 patients(6.0%), of whom 2 patients(1.7%)were surgically treated. The mean duration for the development of ASDz was69.1months ± 3.9months. The development of ASDz and revision surgery was more common in Group A. There was a significant difference between the two groups(P<0.05). The mean duration for the development of ASDz was shorter in Group A. There was a significant difference between the two groups(P<0.05).Conclusion: In patients who underwent anterior cervical arthrodesis for degenerative disease, the development of ASDz was related to the patient post-operative sagittal alignment and cervical spine ROM. Additional plate augmentation during anterior cervical arthrodesis can lower the rate of development of ASDz. |
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