Pitfalls preventing bone union with EXOGEN Low-Intensity Pulsed Ultrasound

Low-Intensity Pulsed Ultrasound Versus Sham in the Treatment of Operatively Managed Scaphoid Nonunions: The SNAPU Randomized Controlled Trial

UPDATE

This article was updated on September 4, 2024 because of a previous error, which was discovered after the preliminary version of the article was posted online. In the Note listing the members of the Wrist and Elbow Research Group of Canada, the text that had read "Thomas T. Goetz, MD, FRCSC" now reads "Thomas J. Goetz, MD, FRCSC".

BACKGROUND

The primary goal after open reduction and internal fixation of an established scaphoid nonunion is to achieve union. Low-intensity pulsed ultrasound (LIPUS) has been reported to increase the rate of union and to decrease the time to union for multiple fractures and nonunions in clinical and animal models. The evidence for LIPUS in the treatment of scaphoid nonunion, however, is sparse. The aim of this study was to assess whether active LIPUS (relative to sham LIPUS) accelerates the time to union following surgery for scaphoid nonunion.

METHODS

Adults with a scaphoid nonunion indicated for surgery were recruited for a multicenter, prospective, double-blinded randomized controlled trial. After surgery, patients self-administered activated or sham LIPUS units beginning at their first postoperative visit. The primary outcome was the time to union on serial computed tomography (CT) scans starting 6 to 8 weeks postoperatively. Secondary outcomes included patient-reported outcome measures, range of motion, and grip strength.

RESULTS

A total of 142 subjects completed the study (69 in the active LIPUS group and 73 in the sham group). The average age was 27 years, and the cohort was 88% male. There was no difference in time to union (p = 0.854; hazard ratio, 0.965; 95% confidence interval, 0.663 to 1.405). Likewise, there were no differences between the active LIPUS and sham groups with respect to any of the secondary outcomes, except for wrist flexion at baseline (p = 0.008) and at final follow-up (p = 0.043).

CONCLUSIONS

Treatment with LIPUS had no effect on reducing time to union in patients who underwent surgical fixation of established scaphoid nonunions.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Low-Intensity Pulsed Ultrasound Therapy in Patients With Post-traumatic Delayed Union and Non-union

Background Fracture non-union can lead to significant patient morbidity with poor quality of life. 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. Of 127 identified patients, only 99 patients met our inclusion criteria. 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. Two independent senior orthopedic doctors reviewed the patients' radiographs, measured the interfragmentary bone gap of all fractures, and assessed whether the radiographic union was achieved. Results The mean age of the included patients was 52.5 (SD±16.9) years with a male-to-female ratio of 1:1.6. At initial presentation, 65 (out of 99) patients were treated surgically, whereas the rest were managed conservatively. 80.8% of patients developed atrophic non-union. 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 rest of the patients needed further surgical intervention due to ongoing non-union. 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. In the current climate post-lockdown and with ongoing Covid 19 outbreaks impacting elective waiting lists negatively, there is increased value and demand for non-surgical treatment options. LIPUS therapy represents an important complementary non-surgical and low-risk treatment pathway for delayed union and non-union.

A Retrospective Study: Is Low-Intensity Pulsed Ultrasound (LIPUS) an Effective Alternate Treatment Option for Non-union?

Background

There is ongoing controversy regarding the use of low-intensity pulsed ultrasound (LIPUS) therapy in patients with delayed union or non-union. Exogen (Bioventus, Durham, NC) is a well-known brand of LIPUS, and according to their data, 86% of non-union fractures will heal without the need for surgery. A few independent retrospective studies reported much lower healing rates.

Method

A retrospective observational study was performed assessing all the patients who underwent Exogen therapy in a single centre. All patients who were initiated on Exogen after three months with radiographic signs of the delayed union were included in the study. Routine follow-up appointments were organised until clinical and radiological healing could be confirmed. Daily 20-minute Exogen sessions were continued until the fracture was healed or up to a maximum of four months as recommended by the manufacturer.

Results

A total of 37 patients received Exogen therapy from 2012 to 2021, of which only 28 patients met our inclusion criteria and were subsequently analysed. The mean age of the patients was 52.0 (SD ± 20.2) with a male to female ratio of 1.7:1. The average time to healing was 115 (±51.2) days with a success rate of 82.14%. The average interfragmentary gap was 7.5 mm (±5.8) for the fractures that healed whereas the failed treatment was 16.1 mm (±13.8). There was no obvious association between outcomes after Exogen therapy and the patient’s age, sex, time to initiate Exogen, diabetes, and smoking status.

Conclusion

This study demonstrated a high success rate of LIPUS therapy for patients with delayed union and non-union. LIPUS represents a safe, non-invasive alternative to revision surgery. An independent risk factor for a potentially poor outcome is an increased interfragmentary gap.