Adjacent-Segment Range of Motion Following Anterior Cervical Fusion: Commentary on an article by William J. Anderst, MS, et al.: “Six-Degrees-of-Freedom Cervical Spine Range of Motion During Dynamic Flexion-Extension After Single-Level Anterior...

第一作者：K. Daniel Riew

2013-04-09 点击量：495 　　我要说

Adjacent-Segment Range of Motion Following Anterior Cervical Fusion: Commentary on an article by William J. Anderst, MS, et al.: “Six-Degrees-of-Freedom Cervical Spine Range of Motion During Dynamic Flexion-Extension After Single-Level Anterior Arthrodesis. Comparison with Asymptomatic Control Subjects”

Anderst et al. have investigated what happens to cervical range of motion above and below a C5-C6 anterior cervical discectomy and fusion in comparison with findings in asymptomatic control subjects who had not undergone an operation. I commend the authors for a well-done study. They used biplanar video fluoroscopy to assess total cervical spine motion and found that this technique was better able to capture the total range of motion, as compared with static flexion-extension radiographic views. At the C4-C5 level, they found that, while the fusion did not decrease the total range of adjacent-level motion, there was increased extension and decreased flexion motion. In addition, there was increased adjacent-segment translation at the levels both cranial and caudal to the fusion level.

The major strength of the study is that the authors utilized an established, reproducible, accurate, and useful technique for documenting motion changes in the cervical spine. They found that, even at only seven months postoperatively, there are subtle motion changes at the segments adjacent to a fusion. While it is easy to conjecture that these changes might result in accelerated degeneration, the clinical relevance of these changes and, more importantly, whether they have anything to do with degeneration that occurs at the adjacent level are not addressed by this study. Published reports of data on arthroplasty versus arthrodesis derived from U.S. Food and Drug Administration investigational device exemption trials failed to show that there is any difference between these two treatments in terms of the incidence of adjacent-segment reoperations at up to five years postoperatively^， Systematic literature review studies have failed to show a difference in adjacent-segment pathology between motion-preserving and arthrodesis procedures. Other reviews have demonstrated no differences in adjacent-segment kinematics between arthrodeses and arthroplasties. Therefore, the impact of a cervical arthrodesis on adjacent segments remains controversial.

The authors state that the patients could not be their own controls because they had pain preoperatively. However, it may still have been better to perform the initial studies on subjects with minimal neck pain and then repeat those studies on the same subjects seven months postoperatively. Patients who are in need of cervical spine surgery are likely to have greater degrees of disc degeneration than asymptomatic controls who do not need surgery. Therefore, it is possible that the operatively treated patients had the findings seen in this study inherently and not because of the fusion; there was no qualitative or quantitative assessment of the extent of their disc degeneration compared with that of the controls.

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