1599. Incidence and Clinical Impact of Vertebral Endplate Changes after Limited Lumbar Microdiscectomy and Implantation of a Bone-anchored Annular Closure Device

Authors: Javier Fandino, MD, IFAANS; Kienzler Jenny, MD; Rey Sofia, MSc; Wetzel Oliver; Hermien Atassi, RN; Bäbler Sabrina, MD; Javier Fandino, MD (Aarau, Switzerland)

 Limited lumbar microdiscectomy (LMD) is the most commonly performed spine surgery with reherniation between 3–18%. The aim of our study was to analyze clinical/radiological outcome after LMD with additional implantation of the Barricaid® annular closure device (ACD) to prevent reherniation.

 Clinical (VAS, ODI), radiological outcome reherniation, implant integrity, endplate changes (EPC) volumetry, disc height and degeneration (Pfirrmann classification) was assessed. Risk factors (smoking, sex, age, localization of implant anchor) for EPC were analyzed in a multivariate multiple regression model.

 72 patients  (37 men,47±11.63yo) underwent LMD and ACD implantation (2013-2016) and completed  F/U with imaging (14.67±4.77months). EPC was documented in 71(99%) patients. In the multivariate regression analysis, the localization of the anchor was the only significant predictor of EPC(p=0.038). The localization in the superior endplate relative to the vertebra leads to larger EPCs in the lower endplate of the adjacent vertebra(p=0.025). In general, EPC were larger in the lower endplate of the vertebra (mean of 476 mm3), compared with those in the upper endplate(mean:180 mm3). The largest EPC measured was 4.18 cm3. Reherniation was documented in 17(24%) patients (symptomatic: n=10; asymptomatic:n=7). Six(8%) patients underwent rediscectomy and 4(6%) patients were treated conservative. Implant failure was documented in 35(49%) patients which included dislocation of the device(n=5,7%), dislocation of the mesh(n=13,18%), and mesh subsidence(n=12,17%). Seven(10%) patients underwent explantation of whole or parts of the device.

 Clinical improvement after LMD and ACD implantation was proven in our study. Despite the fact that EPC was observed in 99% of the patients, EPC volume did not correlate with clinical outcome.  Mechanical friction of the polymer mesh to the endplate might be the cause of the high incidence and severity of EPC after implantation of the Barricaid® ACD. Long-term clinical and radiological assessment are necessary to evaluate the consequences of these findings.