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Sagittal Progression of Ossification After Posterior Cervical Surgery for Ossification of the Posterior Longitudinal
Takumi Nishimura1, Masashi Uehara2, Shota Ikegami1
1Department of Orthopaedic Surgery, Shinshu University School of Medicine, Nagano, Japan.
Background:
Several risk factors have been associated with sagittal progression of ossification of the posterior longitudinal ligament (OPLL), yet there remains no consensus regarding its postoperative behavior. This study investigated the longitudinal changes in OPLL following posterior cervical surgery and aimed to identify factors related to postoperative sagittal progression.
Methods:
Twenty-six patients (23 men and 3 women; mean age 62.0 ± 13.1 years) who underwent posterior cervical spine surgery for OPLL and at least 1 year of computed tomography follow-up were retrospectively reviewed. Changes in the ossification index (OP-index), defined as the sum of ossified vertebral and intervertebral levels, were evaluated using serial computed tomography scans. Postoperative sagittal OPLL progression was defined as an OP-index increase ≥1 point over the preoperative OP-index score. Univariate and multivariate logistic regression analyses were conducted to identify associated factors.
Results:
Postoperative sagittal OPLL progression was observed in 13 of 26 patients (50%). Progression tended to be more frequent in fusion cases than in nonfusion cases (58.8% vs 33.3%, P = 0.41). Multivariate analysis revealed segmental-type OPLL as an independent risk factor for postoperative sagittal progression (OR 17.6, 95% CI 1.14-272). Mean follow-up duration was 35.3 ± 24.8 months. Among the patients who showed postoperative sagittal OPLL progression, the mean time to progression was 26.0 ± 19.0 months. No significant associations were found between OPLL advancement and age, sex, body mass index, nutritional status, number of fused levels, or duration of follow-up. Sagittal OPLL progressed inside the fused segment in 90% of fusion cases.
Conclusion:
Postoperative sagittal OPLL progression can occur regardless of fusion surgery, with a potentially higher risk in patients with the segmental type. Long-term postoperative studies are needed to clarify ossification dynamics in OPLL patients.
Clinical Relevance:
Postoperative sagittal progression of cervical OPLL may occur regardless of posterior fusion surgery, particularly in patients with segmental-type OPLL.
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