Long-Term Range of Motion and Influence on Clinical Outcomes After Lumbar Disc Replacement: A Systematic Review

Study Design: Systematic review. Objective: Lumbar disc replacement (LDR) is a motion-preserving treatment for degenerative disc disease. However, questions remain regarding the durability of segmental range of motion (ROM) over time and its relationship to patient-reported outcome measures (PROMs) and adjacent segment disease (ASD). The purpose of this analysis is to evaluate current clinical evidence regarding the long-term preservation of segmental ROM after LDR, identify predictors of preserved motion, and assess associations with clinical outcomes. Methods: A systematic review was conducted according to PRISMA guidelines. Studies reporting postoperative ROM following LDR with at least 24 months of follow-up were included. Pooled weighted averages and meta-analyses compared ROM at standardized time points with preoperative baselines. Data on predictors of ROM, PROMs, and ASD was qualitatively synthesized. Results: Twenty-seven studies comprising 2563 LDRs were included. Compared with preoperative baseline, ROM declined at <6 months (mean difference [MD] = −0.69, P < 0.0001), then returned to baseline at 12 months (MD = 0.02, P = 0.883), increased at 24 months (MD = 0.48, P < 0.0001), and declined below baseline ≥60 months (MD = −1.55, P < 0.0001). Nine studies assessing PROMs reported positive or neutral correlations with ROM. Three studies evaluated the association between ROM and ASD with two finding reduced ASD rates with greater motion. No consistent predictors of preserved ROM were identified. Conclusion: Segmental ROM decreases gradually in the long term after LDR. While preserved motion may be associated with improved clinical outcomes and reduced ASD, current evidence is inconclusive. Level of Evidence: IV.