Ultrasound-guided Percutaneous Cryoneurolysis for the Treatment of Pain after Traumatic Rib Fracture: A Randomized, Active-controlled, Participant- and Observer-masked Study

Background: Traumatic rib fractures are associated with pain lasting weeks to months and a decreased ability to inspire deeply or cough to clear secretions. Ultrasound-guided percutaneous cryoneurolysis involves reversibly ablating peripheral nerve(s) using exceptionally low temperature with a transdermal probe, resulting in a prolonged nerve block with a duration measured in months. The authors hypothesized that cryoneurolysis would improve analgesia and inspired volume after rib fracture. Methods: Adults with one to six traumatic rib fractures were randomized to either active cryoneurolysis and sham peripheral nerve block or sham cryoneurolysis and active peripheral nerve block in a participant/observer-masked fashion. The primary endpoint was the maximum inspired volume the day after the procedure as measured with an incentive spirometer. Results: The day after the procedure, the unadjusted median [interquartile range] maximum inspired volume for participants who received cryoneurolysis (n = 11) was 2,250 ml [1,500, 2,500 ml] versus 1,300 ml [750, 2,500 ml] for peripheral nerve block (n = 9, mean difference, 496; 95% CI, –428 to 1,420; t test P = 0.269). When adjusted for covariates (e.g., baseline lung volume), the cryoneurolysis group had an estimated 793 ml greater mean volume than peripheral nerve block (95% CI, 273 to 1,312 ml; analysis of covariance P = 0.005). Improvement from baseline in maximum inspired volume for cryoneurolysis was 1,000 ml [1,000, 1,375 ml] versus 300 ml [0, 1,000 ml] for peripheral nerve block (t test P = 0.002). This was equivalent to an improvement over baseline of 100% [90%, 188%] for cryoneurolysis versus 30% [0%, 50%] for peripheral nerve block (t test P = 0.003). Average daily pain scores were generally lower for the cryoneurolysis group throughout the first month. Total cumulative oxycodone equivalents were 5 mg [0, 13 mg] for cryoneurolysis versus 45 mg [43, 135 mg] for peripheral nerve block (t test P = 0.013). conclusions: Ultrasound-guided percutaneous cryoneurolysis improves maximum inspired lung volume while concurrently decreasing pain and opioid consumption after traumatic rib fracture. These results should be considered preliminary, requiring confirmation with a trial including a larger sample size.