Temporal patterns of clinical response following autologous peripheral blood mononuclear cells, continuous radiofrequency, and corticosteroid injections in lumbar facet syndrome: A single-center retrospective observational study

Introduction. Lumbar facet syndrome is one of the most common causes of chronic low back pain and functional disability. Intra-articular corticosteroid injections (CS) are widely used for short-term pain control. Continuous radiofrequency (CRF) of the lumbar medial branch is a well-established minimally invasive technique for the treatment of chronic facet-mediated pain, generally providing a more sustained clinical benefit over time. Autologous peripheral blood mononuclear cells (PBMNCs) represent an emerging biological therapy with potential immunomodulatory effects on chronic inflammatory processes. The aim of this study was to evaluate the temporal patterns of clinical response associated with these three treatment modalities in patients with chronic lumbar facet syndrome.Methods. This single-center retrospective observational study included 90 patients (56.4 years ± 9.8 SD) with chronic lumbar facet syndrome and severe low back pain evaluated at Numeric Rating Scale (NRS) ≥ 7, diagnosed through clinical assessment, imaging findings, and a positive response to diagnostic anesthetic blocks. All patients failed conservative treatment (physiotherapy and oral nonsteroidal anti-inflammatory drugs) after at least 3 months of therapy. Patients were allocated to three treatment groups, with 30 patients in each group: one group received Rx-guided intra-articular injection of PBMNCs; another group underwent CRF of the lumbar medial branch at 80°C; and the last group received Rx-guided intra-articular CS injection. Pain intensity was assessed using the NRS, functional disability using the Oswestry Disability Index (ODI), and health-related quality of life using the Short Form Health Survey (SF-12) questionnaire. Assessments were performed at baseline (T0) and at 1-month (T1), 3-month (T2), 6-month (T3), 8-month (T4) and 12-month (T5) follow-up visits.Results. Baseline demographic and clinical characteristics were comparable among groups. All treatment groups demonstrated clinically significant improvement compared with baseline in all rating scales (P < 0.05). No major adverse events were reported in all three groups during the treatments. The CS group showed the most rapid short-term pain relief, with mean NRS scores decreasing from 7.8± 0.9 to 3.4± 1.1 at 1 month, followed by a progressive decline in efficacy at subsequent follow-up assessments. The CRF group exhibited early improvement at T1 (NRS reduction from 7.7 ± 1.0 to 3.1 ± 1.2), with maintenance of clinical benefit for approximately 6 months before symptom recurrence at longer-term follow-up. In the PBMNC group, a distinct response profile was observed, with significant improvement observed at T1 and maintenance of clinical benefit for approximately 8 months, followed by a reduction in treatment effect at T5 follow-up.Conclusions. PBMNC therapy, continuous radiofrequency, and corticosteroid injections are effective minimally invasive treatment options for chronic lumbar facet syndrome. The three interventions demonstrated distinct temporal patterns of clinical response. Corticosteroids provided rapid but short-lived pain relief, CRF offered earlier and more sustained medium-term benefit, whereas PBMNC therapy was associated with maintenance of clinical benefit for up to approximately 8 months. These distinct temporal profiles may support a more individualized therapeutic approach based on patient characteristics and treatment objectives.