Predictive Value of Synovial Hypertrophy and Synovial Effusion on Ultrasound for Clinical Outcomes of Genicular Nerve Ablation in Knee Osteoarthritis

Abstract Background: Genicular nerve ablation (GNA) is an effective minimally invasive intervention for pain relief in knee osteoarthritis (OA). However, the predictive role of pre-procedural ultrasound findings, particularly synovial effusion (SE) and hypertrophy, remains underexplored. This study aimed to evaluate whether these sonographic parameters predict short-term outcomes following GNA. Materials and Methods: This observational study included 24 patients with chronic knee OA who underwent ultrasound-guided GNA targeting the superior medial, superior lateral, and inferior medial genicular nerves. SE and hypertrophy were graded according to Outcome Measures in Rheumatology and quantitative effusion thickness. Pain and function were assessed using the Numeric Rating Scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and 4 weeks post-procedure. Patients achieving ≥50% NRS reduction were defined as responders. Predictive factors were analyzed using Firth logistic regression. Results: Mean NRS improved from 6.75 ± 0.99 to 3.88 ± 1.83 ( P < 0.001), and mean WOMAC improved from 38.5 ± 3.9 to 15.7 ± 13.7 ( P < 0.001). Patients with mild or no SE showed greater improvement (WOMAC reduction = 33 points) than those with moderate/severe effusion (18 points). Similarly, mild/no hypertrophy showed a larger WOMAC decrease (28 vs 19 points). Firth logistic regression identified synovial hypertrophy (SH) as an independent predictor of response (adjusted odds ratios (OR) = 8.75; 95% confidence intervals 1.86–41.10; P = 0.007), whereas effusion showed a nonsignificant trend (OR = 0.67; P = 0.47). Conclusion: GNA provides significant short-term improvement in pain and function in knee OA. Ultrasound assessment of the synovial morphology enhances prognostication—patients with minimal SH and effusion demonstrate the greatest likelihood of favourable outcomes. Incorporating pre-procedural ultrasound phenotyping into routine evaluation may optimize patient selection and clinical success of GNA.