Introduction: Lumbar spondylolysis is a fatigue fracture of the pars interarticularis. When diagnosed early, bone healing can often be achieved through bracing. However, some cases fail to heal in patients unable to use bracing or because they are already in an advanced stage at the time of diagnosis, making union difficult. Given that extracorporeal shock wave therapy (ESWT) has shown bone-healing effects in fresh fractures and pseudarthrosis of long bones, we hypothesized that it may be beneficial for lumbar spondylolysis as well. This study investigated the safety and efficacy of ESWT for patients with lumbar spondylolysis.

Methods: We included 46 patients (64 lesions) diagnosed with lumbar spondylolysis between January 2022 and June 2024 at our institution, all of whom consented to participate and were available for follow-up. Treatment was conducted using the DUOLITH (STORZ MEDICAL) system, with fluoroscopy marking the lesion site, and shock waves were applied biweekly to painful areas. Intensity was adjusted to the tolerable range of 0.15-0.25 mJ/mm², with 3,000 pulses per session. We assessed complication rates, bone union rates, and time to bone union.

Results: No complications, such as nerve damage or ligament ossification, were observed. The overall bone union rate was 78%, with an average time to union of 2.5 months. By disease stage, union rates and times were as follows: 100% union in 1.7 months for 18 cases in the earliest stage; 100% union in 2 months for 15 cases in the early stage; 76% union in 3 months for 16 cases in the progressive stage; and 10% union in 12 months for 10 cases in the end stage.

Conclusions: Despite including 22 patients who underwent ESWT without bracing to continue sports activities, the bone union rate and time to union were both improved compared to traditional methods. ESWT provides a promising, non-invasive treatment option for lumbar spondylolysis, offering high union rates and expedited healing times.