Association Between Histological Composition and Clinical Symptoms in Lumbar Disk Herniation in Different Age Groups

Study Design. Retrospective study of prospectively collected data. Objective. To investigate the influence of cartilaginous endplates (CEs) in herniated disks on clinical symptoms and postoperative outcomes in patients with lumbar disk herniation (LDH) in different age groups. Summary of Background Data. LDH involving CEs, which are hard and less resorptive, is frequently observed with increasing age and appears to affect the natural course and clinical outcomes following discectomy. Methods. Overall, 239 patients who underwent microscopic discectomy were included. Main outcomes were evaluated using motor strength, visual analog scale (VAS) for back and leg pain, and Rolland-Morris Disability Questionnaire. The effects of CEs on clinical variables and postoperative outcomes were compared between two groups (below 50 and 50 y or above). Furthermore, we investigated the characteristics of CE avulsions in each group and examined the association between CE occupancy rate and clinical symptoms. Results. CEs were predominantly observed with increasing age and were more frequently detected in patients with Modic changes in both groups ( P <0.001). A higher proportion of LDH with a ≥20% occupancy rate was found in patients aged below 50 years ( P =0.009) and was associated with a decrease in motor strength preoperatively ( P =0.007). Postoperative VAS score for low back pain (LBP) was higher in patients with CEs than in those without CEs in the 50-year-old or above group ( P <0.001). In multiple regression analysis, the presence of CEs was independently associated with residual LBP at one year postoperatively in older patients (β=0.46, P <0.001). Conclusions. Avulsion-type herniations in patients aged below 50 years had a higher CE occupancy rate, which is a potential cause of preoperative motor weakness. Clinical outcomes following discectomy improved regardless of the presence of CEs; however, cartilaginous herniation in patients aged 50 years or above may affect residual LBP at one year.