Ultrasound-Guided Atelocollagen Injection for Chronic Pain After Spinal Surgery: A Retrospective Cohort Study

Chronic pain after spinal surgery (CPSS), formerly known as failed back surgery syndrome (FBSS), is a persistent and complex condition that often resists conventional treatments. Recent attention has turned toward paraspinal muscle degeneration as a contributing factor. Injectable type I porcine atelocollagen, known for its anti-adhesive and regenerative properties, has been proposed as a potential intervention, but clinical evidence remains scarce. This study aimed to evaluate the effect of ultrasound-guided atelocollagen injection into paraspinal muscles for patients with CPSS and to identify potential predictors of treatment response.

This single-center retrospective cohort study was conducted at a tertiary academic institution. 34 adult patients (≥20 years) with a diagnosis of lumbosacral CPSS who received ultrasound-guided purified porcine atelocollagen injections between October 2020 and December 2023 and completed 3-month follow-up without concurrent interventional procedures or medication escalation were included in the analysis. The injection was performed into the paraspinal muscles at the surgical level. The primary outcome was change in pain intensity on the 11-point numeric rating scale (NRS) at 3 months post-treatment. A composite outcome was defined as a ≥1-point reduction in NRS or a Patient Global Impression of Change (PGIC) score of 4 or 5. Exploratory analyses were conducted to identify potential predictive factors.

The mean NRS score significantly decreased by 1.62 points (95% CI 0.91-2.33, p<0.001) at 3 months after atelocollagen injection compared to baseline. Neither univariable nor multivariable logistic regression analysis revealed any significant predictive factors for a positive composite outcome. When comparing the responder and non-responder groups based on the composite outcome, the proportion of patients taking anticonvulsants or antidepressants was significantly higher in the non-responder group (54.2% vs 100%, p = 0.028).

Ultrasound-guided atelocollagen injection into the paraspinal muscles was associated with pain reduction in patients with CPSS. Although the absence of a control group limits causal interpretation, this suggests that atelocollagen injection may have potential as an adjunctive or investigational treatment option for this patient population.