Due to the cost, complexity, and potential risks of revision surgery, there has been an increased popularity in the use of low-intensity pulsed ultrasound therapy (LIPUS), which accelerates and promotes bone consolidation.  There is an ongoing debate regarding the use and efficacy of LIPUS in delayed union and non-union.  This study aims to assess the success rate of LIPUS therapy in patients treated for delayed and non-union fractures, explicitly focusing on the impact of patient co-morbidities and fracture characteristics.  Method A retrospective observational study was performed of all consecutive patients who received LIPUS therapy in a single institution from January 2016 to September 2022.  Data collection entailed reviewing the clinical notes to assess patients' sex, age, co-morbidities, initial treatment method, time to initiate LIPUS, whether a CT was performed to diagnose non-union, time to union and whether revision surgery was needed.  All 99 included patients were fitted with LIPUS once delayed/ non-union was diagnosed; the average time to fitting was 5.1 (SD±3.9) months.  Of these, 61.6% of patients were successfully treated with LIPUS with a clinical and radiological union at an average of 4.3 (SD±1.9) months.  The interfragmentary bone gap was the only statistically significant factor influencing the success of LIPUS therapy (p=0.003).  In contrast, no statistically significant association was identified between the outcome of LIPUS therapy and the patient's age, sex, diabetes, and smoking status.  Conclusion This study demonstrated a 61.6% progression to union rate of patients treated with LIPUS therapy for delayed union and non-union.  The interfragmentary bone gap was identified as the only statistically significant factor influencing the success of LIPUS therapy.  LIPUS therapy represents an important complementary non-surgical and low-risk treatment pathway for delayed union and non-union.
LIPUS