Postoperative magnetic resonance imaging assessment for potential compressive effects of retained posterior longitudinal ligament after anterior cervical fusions: a cross-sectional study.

STUDY DESIGN: A cross-sectional study.

OBJECTIVE: To assess using postoperative magnetic resonance imaging whether the posterior longitudinal ligament (PLL) caused residual cord compression after anterior cervical decompression and fusion (ACDF) in a series of patients in whom the PLL was retained.

SUMMARY OF BACKGROUND DATA: There is a lack of data evaluating the postoperative compressive effects of the PLL in patients undergoing ACDF providing guidance as to whether to remove or retain the PLL during discectomy to facilitate adequate decompression.

METHODS: Postoperative gadolinium enhanced magnetic resonance images were reviewed in a series of 33 patients who underwent ACDF for cervical radiculomyelopathy and who had persistent or recurrent postoperative symptoms. Patients with ossification of the posterior longitudinal ligament or with a herniated disc behind the PLL were excluded from this study.

RESULTS: There were no cases of discernible compression by the retained PLL identified on the magnetic resonance image (P < 0.001) as assessed by 2 independent reviewers. Four patients underwent subsequent revision surgery unrelated to the PLL.

CONCLUSION: We were unable to demonstrate magnetic resonance imaging evidence to suggest that the retained PLL caused compression after ACDF in this patient cohort. Therefore we suggest that removing the PLL should be considered for reasons other than concern about residual compression.