Long-term outcomes of microdiscectomy with or without dynamic stabilization for midline lumbar disc herniation

Midline (central) lumbar disc herniation (MLDH) is an uncommon and challenging condition with no consensus on the optimal surgical approach. While microdiscectomy alone remains the most widely used approach, the role of adjunctive posterior dynamic stabilization in mitigating long-term functional deterioration is unclear, and the existing literature on dynamic stabilization following discectomy includes both supportive and unfavorable evidence. This study evaluates the clinical outcomes of microdiscectomy alone versus microdiscectomy with posterior dynamic stabilization in patients with MLDH. A retrospective single-center analysis was conducted on 51 patients who underwent surgery for MLDH between February 2018 and December 2021. Patients were divided into two groups: 33 underwent microdiscectomy alone, while 18 received additional dynamic stabilization. Pain affecting activities of daily living (ADL) was defined using validated instruments as an Oswestry Disability Index score above 20% together with a Visual Analog Scale score above 3.5, indicating at least moderate disability and pain attributable to the index-level pathology. Baseline differences between groups were assessed for all radiological parameters as potential confounders. Radiological parameters such as Pfirrmann grade, annular tear size, sacralization, and Modic changes were analyzed. Outcomes were the proportion of patients with ADL-affecting pain, revision surgery, and time from operation to onset of ADL-affecting pain. Mean age was 46.55 ± 16.42 years; 45.1% were female. Baseline radiological parameters did not differ significantly between groups (annular tear: p = 0.13; Pfirrmann grade: p = 0.61; Modic degeneration: p = 0.60; sacralization: p = 0.70). Mean follow-up was 57.95 ± 12.90 months. At long-term follow-up, the composite adverse outcome (ADL-affecting pain or revision) occurred in 11 of 33 microdiscectomy patients (33.3%) and 2 of 18 stabilization patients (11.1%), Fisher exact p = 0.103. Among patients with early postoperative pain, resolution by long-term follow-up was 30.8% (4/13) in the microdiscectomy group versus 85.7% (6/7) in the stabilization group. Time-to-event analysis showed event-free survival of 44% at the end of follow-up in the microdiscectomy group (median survival 66 months) versus 89% from 31 months onward in the stabilization group (median survival not reached); χ² = 3.93, p = 0.047. Stabilization was associated with a lower hazard of the composite adverse outcome, reaching borderline statistical significance with the Mantel–Haenszel method (HR, 0.32; 95% CI, 0.10–0.99) and statistical significance with the log-rank–based method (HR, 0.25; 95% CI, 0.08–0.76). In this retrospective, non-randomized real-world cohort of patients with MLDH, the primary categorical comparison of the composite adverse outcome and the adjusted multivariable analysis did not reach conventional statistical significance; only the time-to-event analysis reached borderline significance. However, the direction of effect consistently favored the addition of posterior dynamic stabilization, which was associated with longer event-free survival and a lower observed hazard of ADL-affecting pain or revision surgery. These findings should be interpreted as associations rather than as evidence of treatment superiority or causal benefit, and are hypothesis-generating. Selected patients with MLDH may benefit from motion-preserving segmental support following decompression. Given the retrospective non-randomized design, potential selection bias, and limited sample size, prospective adequately powered comparative studies with standardized patient-reported and radiographic outcomes are required to determine whether this observed association reflects a true causal benefit.