Pulsed ultrasounds accelerate healing of rib fractures in an experimental animal model: an effective new thoracic therapy?

Pulsed Ultrasounds Reduce Pain and Disability, Increasing Rib Fracture Healing, in a Randomized Controlled Trial

INTRODUCTION

Rib fractures are an important health issue worldwide, with significant, pain, morbidity, and disability for which only symptomatic treatment exists.

OBJECTIVES

Based on our previous experimental model, the objective of the current study was to assess for the first time whether pulsed ultrasound (PUS) application could have beneficial effects on humans.

METHODS

Prospective, double-blinded, randomized, controlled trial of 51 patients. Four were excluded, and 47 were randomized into the control group (N = 23) or PUS group (N = 24). The control group received a PUS procedure without emission, and the PUS group received 1 Mhz, 0.5 W/cm2 for 1 min/cm2. Pain level, bone callus healing rate, physical and work activity, pain medication intake, and adverse events were blindly evaluated at baseline and one, three, and six months.

RESULTS

There were no significant differences at baseline between groups. PUS treatment significantly decreased pain by month 1 (P = 0.004), month 3 (P = 0.005), and month 6 (P = 0.025), significantly accelerated callus healing by month 1 (P = 0.013) and month 3 (P < 0.001), accelerated return to physical activity by month 3 (P = 0.036) and work activity (P = 0.001) by month 1, and considerably reduced pain medication intake by month 1 (P = 0.057) and month 3 (P = 0.017). No related adverse events were found in the PUS group.

CONCLUSIONS

This study is the first evidence that PUS treatment is capable of improving rib fracture outcome, significantly accelerating bone callus healing, and decreasing pain, time off due to both physical activity and convalescence period, and pain medication intake. It is a safe, efficient, and low-cost therapy that may become a new treatment for patients with stable rib fractures.

The effect of low-intensity pulsed ultrasound on rib fracture: An experimental study

Background

In this study, we aimed to investigate the effects of lowintensity pulsed ultrasound on rib fracture healing in a rat model.

Methods

A total of 72 male Wistar-Albino rats were randomly divided into three equal groups. To induce a rib fracture, right thoracotomy was performed under general anesthesia and a 0.5-cm segment was removed from the fourth and fifth ribs. After 24 h of surgery, low-intensity pulsed ultrasound was implemented according to the groups. Group 1 served as the control group for the observation of normal bone healing. Low-intensity pulsed ultrasound was applied at a dose of 20% (2 msn pulse-8 msn pause) 100 mW/cm2 and 50% (5 msn pulse-5 msn pause) 200 mW/cm2 for six min, respectively in Group 2 and Group 3. All subjects were followed for six weeks. Eight animals from each group were sacrificed at two, four, and six weeks for further assessment. Histological alterations in the bone were examined.

Results

Although there was no statistically significant difference in osteoblasts, osteoclasts, new bone formation, and lymphocyte count among the groups, histological consolidation was significantly increased by low-intensity pulsed ultrasound. While low-intensity pulsed ultrasound induced osteoblastic, osteoclastic, and new bone formation, it inhibited lymphocyte infiltration.

Conclusion

Low-intensity pulsed ultrasound, either at low or high doses, induced the histological consolidation of rib fractures and inhibited lymphocyte infiltration. This effect was more prominent in the long-term and at higher dose with increased daily and total administration time. We, therefore, believe that accelerating the natural healing process in patients with rib fractures would enable to treat more effectively in short-term.

Systemic administration of mesenchymal stem cells combined with parathyroid hormone therapy synergistically regenerates multiple rib fractures

Background

A devastating condition that leads to trauma-related morbidity, multiple rib fractures, remain a serious unmet clinical need. Systemic administration of mesenchymal stem cells (MSCs) has been shown to regenerate various tissues. We hypothesized that parathyroid hormone (PTH) therapy would enhance MSC homing and differentiation, ultimately leading to bone formation that would bridge rib fractures.

Methods

The combination of human MSCs (hMSCs) and a clinically relevant PTH dose was studied using immunosuppressed rats. Segmental defects were created in animals’ fifth and sixth ribs. The rats were divided into four groups: a negative control group, in which animals received vehicle alone; the PTH-only group, in which animals received daily subcutaneous injections of 4 μg/kg teriparatide, a pharmaceutical derivative of PTH; the hMSC-only group, in which each animal received five injections of 2 × 10⁶ hMSCs; and the hMSC + PTH group, in which animals received both treatments. Longitudinal in vivo monitoring of bone formation was performed biweekly using micro-computed tomography (μCT), followed by histological analysis.

Results

Fluorescently-dyed hMSCs were counted using confocal microscopy imaging of histological samples harvested 8 weeks after surgery. PTH significantly augmented the number of hMSCs that homed to the fracture site. Immunofluorescence of osteogenic markers, osteocalcin and bone sialoprotein, showed that PTH induced cell differentiation in both exogenously administered cells and resident cells. μCT scans revealed a significant increase in bone volume only in the hMSC + PTH group, beginning by the 4^th week after surgery. Eight weeks after surgery, 35% of ribs in the hMSC + PTH group had complete bone bridging, whereas there was complete bridging in only 6.25% of ribs (one rib) in the PTH-only group and in none of the ribs in the other groups. Based on the μCT scans, biomechanical analysis using the micro-finite element method demonstrated that the healed ribs were stiffer than intact ribs in torsion, compression, and bending simulations, as expected when examining bone callus composed of woven bone.

Conclusions

Administration of both hMSCs and PTH worked synergistically in rib fracture healing, suggesting this approach may pave the way to treat multiple rib fractures as well as additional fractures in various anatomical sites.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0502-9) contains supplementary material, which is available to authorized users.