Medium and long term clinical outcomes of artificial cervical disc replacement

English Keywords:Cervical spondylosis  Artificial cervical disc replacement  Medium and long-term follow-up  Clinical efficacy

English Abstract:

  【Abstract】 Objectives: To retrospectively analyze the mid- and long-term clinical outcomes and complica?鄄tions of artificial cervical disc replacement(ACDR) in cervical spondylosis. Methods: A total of 68 patients with cervical spondylosis who received ACDR treatment in our department from May 2009 to May 2015 were included in this study. Among them, 32 cases were males and 36 cases were females; the average age was 39.1±6.2 years(23-55 years). There were 42 cases of cervical spondylotic myelopathy, 19 cases of nerve root type cervical spondylosis, and 7 cases of mixed cervical spondylopathy. The preoperative course of disease was 9.5 to 21.5 months(14.5±6.3 months). 52 patients received single-segment ACDR and 16 patients re?鄄ceived two-segment ACDR. The artificial disc was a Discover prosthesis. The Japan Orthopedic Association(JOA) score, the pain visual analogue scale(VAS) score, and the cervical disability index(neck disability index, NDI) were used to assess the patient′s neurological function and clinical symptoms; cervical spine X-rays were used to assess the patient′s cervical curvature(C2-C7 Cobb angle) before operation, after operation and final follow-up. The range of motion of the operative segment was measured by X-ray of cervical hyperflexion and extension. The osteophyte formation in the adjacent segment was observed on the lateral X-ray films. The osteophyte formation grade was used to judge the degeneration of the adjacent segment. Cervical CT plain scan + three-dimensional reconstruction and McAfee classification method were used to evaluate the hetero?鄄topic ossification(HO) of the surgical segment. The postoperative axial symptoms and other complications were recorded. Results: The follow-up period was 78 to 132 months(averaged 98.3±17.2 months). During the follow-up period, neurological function and clinical symptoms were improved. On the second day after surgery, the cervical curvature of the included patients was significantly improved than that before surgery(12.5°±3.9° vs 9.3°±5.5°, P=0.044). At final follow-up, the cervical spine curvature(C2-C7 Cobb angle) was not significantly different from that before surgery(10.3°±4.2° vs 9.3°±5.5°, P=0.181). The range of motion increased from 6.5°±3.4° before surgery to 8.7°±2.8° on the second day after surgery(P=0.001), 8.2°±3.8° at 1 year follow-up, 7.5°±4.1° at 2 years follow-up, and 5.3°±4.8° at the 5-year follow-up. At final follow-up, the range of motion of the surgical segment was 4.5°±2.7°, which was significantly lower than that before operation and 1 year after operation(P=0.021, P=0.019). At final follow-up, the grades of osteophyte formation in adjacent segments on the cephalic and caudal sides increased by 0.46 and 0.41 respectively. The incidence of axial symptoms dropped to 4.41% during follow-up after 1 year(2 cases in the single-segment group and 1 case in the two-segment group). 5 years after the operation, the patients had no complaints of neck pain. At final follow-up, 46 patients(67.65%) with 51(60.71%) surgical segments had varying degrees of HO manifestations. The incidence of HO in two segment group was significantly higher than that in single segment group(81.25% vs 63.46%, P=0.048). Conclusions: ACDR has a good mid- to long-term clinical effect in cervical spondylosis, but postoperative complications such as HO cannot be ignored. Its protective effect on the degeneration of adjacent segments needs further observation and follow-up.