Anterior-Only Decompression Fails in Multisegmental Concentric Stenosis: Indicators for Secondary Posterior Surgery

Background: The compression of the spinal cord can result in degenerative cervical myelopathy (DCM), a condition characterized by progressive neurological dysfunction. This study examines clinical outcomes after anterior decompression and predictors of secondary posterior decompression after initial anterior surgery. Methods: In this retrospective single-center study, 94 patients who underwent anterior cervical decompression between 2020 and 2024 were analyzed. Demographic, clinical (e.g., Japanese Orthopaedic Association (JOA) score, American Society of Anesthesiologists (ASA) classification), and radiological parameters (stenosis type, number of levels involved, spinal cord shift) were collected. Multivariable logistic regression analysis, likelihood ratio model and Mann-Whitney-U-Test were employed to identify independent predictors for the necessity of a secondary posterior decompression. Results: In nine patients (9.5 %), secondary posterior decompression was necessary. All of these patients presented with preoperative concentric stenosis, representing 20.1 % of that subgroup. Patients with a concentric stenosis significantly presented with lower JOA scores (12.4 ± 2.7) than patients with a non-concentric stenosis (14.1 ± 1.9). Non-concentric stenosis was associated with a markedly lower reoperation likelihood (p = 0.019). Sequential likelihood-ratio showed that besides concentric-stenosis, a multisegmental pathology increased the probability of a secondary posterior surgery. In addition, patients that required secondary surgery had a significantly smaller anterior epidural space after first anterior decompression. Conclusions: Preoperative multisegmental concentric stenosis significantly predicted secondary posterior decompression. In addition, postoperative limited anterior epidural space highlights that ventral decompression alone inadequately addresses circumferential compression.