Lumbar facet joint osteoarthritis as the underlying reason for persistent low back pain after minimally invasive discectomy

Introduction A post-hoc subgroup analysis of prospective collected data in a randomized controlled trial (RCT) of minimally invasive discectomy was conducted, to find out the possible underlying reasons for patients with persistent low back pain (LBP) following surgery. Materials and methods Patients who were diagnosed with lumbar disc herniation (LDH) and underwent either percutaneous transforaminal endoscopic discectomy or microendoscopic discectomy in our RCT were analyzed. Patients with persistent LBP in 2-year follow-up were compared with the non-LBP patients to determine the underlying reasons. Then, the demographic characteristics, clinical outcomes and radiological parameters of patients with preoperative lumbar facet joint osteoarthritis (LFJOA) were assessed and compared with the non-LFJOA subgroup. Results 18 patients (8.1%) were reported to have persistent LBP in 2-year follow-up. Significantly higher proportion of preoperative LFJOA were found in the persistent LBP subgroup and was considered to be a risk factor using multivariate analysis. The prevalence of LFJOA is strongly associated with older age, female, high BMI and heavy labor in the LDH population. All of the clinical outcomes including ODI, SF36-PF, SF36-BP, EQ-5D, VAS-back and VAS-leg were worse in LFJOA subgroup in 2-year follow-up. LFJOA subgroup was associated with more adjacent segment degeneration and more lateral recess stenosis. Conclusions LFJOA is a possible underlying reason for patients with persistent LBP after minimally invasive discectomy. Surgeons should carefully review the preoperative radiological images to find out whether there is LFJOA in the LDH segment, and kindly diminish the expectation of back pain relief for those patients. Trial registration : This trial was registered at ClinicalTrials.gov at November 14, 2013, registration number NCT01997086. ( https://clinicaltrials.gov/ct2/show/NCT01997086 ).