Low-intensity pulsed ultrasound in the treatment of nonunions.

BACKGROUND: Low-intensity ultrasound has demonstrated an acceleration of bone healing and more profound callus formation in animal and human clinical experiments. In this study, the effect of pulsed, low-intensity ultrasound was determined in established nonunion cases. METHODS: The enrolled cases were reviewed for the time from their last surgical procedure and evidence of no healing or progression of healing during the 3 or more months before the start of low-intensity ultrasound therapy to determine whether the cases were established nonunions. Twenty-nine cases, located in the tibia, femur, radius/ulna, scaphoid, humerus, metatarsal, and clavicle, met the criteria for established nonunions. On average, the postfracture period before the start of ultrasound treatment was 61 weeks. Initial fracture treatment was conservative in 8 cases and operative in 21 cases. Additional treatments including bone grafting, reosteosynthesis, and other surgical procedures were performed an average of 52 weeks before the start of ultrasound treatment. Daily, 20-minute applications of low-intensity ultrasound at the site of the nonunion were performed by the patients at home. RESULTS: Twenty-five of the 29 nonunion cases (86%) healed in an average treatment time of 22 weeks (median, 17 weeks). Stratification of the healed and failed outcome for age, gender, concomitant disease, bone location, fracture age, prior last surgery interval, nonunion type, smoking habits, and fixation before and during treatment showed a significant difference only in the smoking habit strata. CONCLUSION: Noninvasive ultrasound therapy can be useful in the treatment of challenging, established nonunions.

Improved cartilage repair after treatment with low-intensity pulsed ultrasound.

Low-intensity pulsed ultrasound accelerates bone healing via upregulation of cartilage formation and maturation phases of endchondral bone formation. The current authors evaluated the effect of ultrasound therapy on the repair of full-thickness osteochondral defects. Bilateral, 3.2 mm diameter by 5.0 mm deep osteochondral defects were created in the patellar groove of 106 adult male New Zealand rabbits. The defects were treated with daily low-intensity pulsed ultrasound therapy on the right knee. The left knee was not treated. In Part I, the effect of ultrasound therapy was evaluated at 4, 8, 12, 24, and 52 weeks after surgery. In Part II, the effect of the length of treatment (5, 10, or 40 minutes of daily ultrasound therapy) compared with standard 20 minute therapy was evaluated. The repair cartilage was evaluated and graded on a standard scale for the gross and histologic appearance. Ultrasound treatment significantly improved the morphologic features and histologic characteristics of the repair cartilage compared with nontreated controls. Earlier, better repair with less degenerative changes at later times was observed in defects treated with ultrasound. Doubling the treatment time to 40 minutes daily significantly increased the histologic quality of the repair cartilage. In the current animal model, daily low-intensity pulsed ultrasound had a significant positive effect on the healing of osteochondral defects.

Low-intensity pulsed ultrasound improves spinal fusion.

BACKGROUND CONTEXT: Increasing the incidence of solid bony fusion is a primary goal in spine surgery. Daily low-intensity pulsed ultrasound therapy has been shown to improve and accelerate the bone healing process. PURPOSE: The purpose of this study was to evaluate the efficacy of daily low-intensity pulsed ultrasound therapy to improve the rate and quality of spinal fusion. STUDY DESIGN: Canine fusion model prospective study. PATIENT SAMPLE: Fourteen adult male dogs were used. OUTCOME MEASURES: Radiographic grading of plain films, computed tomography (CT) and magnetic resonance imaging (MRI), gross palpation, torsional stiffness and histologic grading were used to determine the presence or absence of fusion. METHODS: Posterior noninstrumented bilateral fusions were evaluated at the L2-L3 and L5-L6 levels. Treatment with low-intensity pulsed ultrasound for 20 minutes per day over the fusion site (stimulated) was compared with fusion sites that received no stimulation (nontreated controls) at 6 and 12 weeks after surgery. Plain film radiographs, CT and MRI, mechanical torsion testing and histologic examination were performed. RESULTS: At 6 weeks, ultrasound treated sites were more frequently fused compared with nontreated controls, although the difference in fusion rate was not statistically significant. At 12 weeks after surgery complete radiographic and histologic fusion occurred in 100% of ultrasound-treated sites. In the nontreated control sites 78% had achieved complete radiographic fusion and 44% had complete histologic fusion. Compared with control sites, the histological and mechanical fusion rate was significantly greater in ultrasound-treated sites (P<.05) at 12 weeks. A statistically significant increase in mechanical stiffness in ultrasound-treated sites was also found at 12 weeks after surgery. CONCLUSIONS: Low-intensity pulsed ultrasound therapy may be a useful means to ensure successful spine fusion.

Enhancement of fracture healing by low intensity ultrasound.

Fracture healing is a highly complex regenerative process that is essentially a replay of developmental events. These events include the action of many different cell types, a myriad of proteins, and active gene expression that in the majority of cases ultimately will restore the bone's natural integrity. Several biologic and biophysical approaches have been introduced to minimize delayed healing and nonunions, some with promising results. One example of such an approach is low intensity pulsed ultrasound, a noninvasive form of mechanical energy transmitted transcutaneously as high frequency acoustical pressure waves in biologic organisms. Numerous in vivo animal studies and perspective double blind placebo controlled clinical trials have shown that low intensity ultrasound is capable of accelerating and augmenting the healing of fresh fractures. Preliminary evidence suggests efficacy in the treatment of delayed healing and nonunions as well. This article reviews the animal and clinical studies that consider the effects of ultrasound on fracture healing, and the in vivo and in vitro work that strives to identify the biologic mechanism(s) responsible for the ultrasound induced enhancement of osteogenesis and fracture healing.

Accelerated healing of distal radial fractures with the use of specific, low-intensity ultrasound. A multicenter, prospective, randomized, double-blind, placebo-controlled study.

A multicenter, prospective, randomized, double-blind, placebo-controlled clinical trial was conducted to test the efficacy of a specifically programmed, low-intensity, non-thermal, pulsed ultrasound medical device for shortening the time to radiographic healing of dorsally angulated fractures (negative volar angulation) of the distal aspect of the radius that had been treated with manipulation and a cast. Sixty patients (sixty-one fractures) were enrolled in the study within seven days after the fracture. The patients used either an active ultrasound device (thirty fractures) or a placebo device (thirty-one fractures) daily for twenty minutes at home for ten weeks. The two types of devices were identical except that the placebo devices emitted no ultrasound energy. Clinical examination was performed and radiographs were made at one, two, three, four, five, six, eight, ten, twelve, and sixteen weeks after the fracture by each site investigator. The time to union was significantly shorter for the fractures that were treated with ultrasound than it was for those that were treated with the placebo (mean [and standard error], 61 +/- 3 days compared with 98 +/- 5 days; p < 0.0001). Each radiographic stage of healing also was significantly accelerated in the group that was treated with ultrasound as compared with that treated with the placebo. Compared with treatment with the placebo, treatment with ultrasound was associated with a significantly smaller loss of reduction (20 +/- 6 per cent compared with 43 +/- 8 per cent; p < 0.01), as determined by the degree of volar angulation, as well as with a significant decrease in the mean time until the loss of reduction ceased (12 +/- 4 days compared with 25 +/- 4 days; p < 0.04). We concluded that this specific ultrasound signal accelerates the healing of fractures of the distal radial metaphysis and decreases the loss of reduction during fracture-healing.

Acceleration of tibia and distal radius fracture healing in patients who smoke.

A low intensity ultrasound device was investigated as an accelerator of cortical and cancellous bone fracture healing in smokers and nonsmokers. Statistically significant reductions in healing time for smokers and nonsmokers were observed for tibial and distal radius fractures treated with an active ultrasound device compared with a placebo control device. The healing time for a tibial fracture was reduced 41% in smokers and 26% in nonsmokers with the active ultrasound device. Similarly, distal radius fracture healing time was reduced by 51% in smokers and 34% in nonsmokers with the active device. Treatment with the active ultrasound device also substantially reduced the incidence of tibial delayed unions in smokers and nonsmokers. The use of the active ultrasound device accelerates cortical and cancellous bone fracture healing, substantially mitigates the delayed healing effects of smoking, speeds the return to normal activity, and reduces the long-term complication of delayed union.

Acceleration of tibial fracture-healing by non-invasive, low-intensity pulsed ultrasound.

Sixty-seven closed or grade-I open fractures of the tibial shaft were examined in a prospective, randomized, double-blind evaluation of use of a new ultrasound stimulating device as an adjunct to conventional treatment with a cast. Thirty-three fractures were treated with the active device and thirty-four, with a placebo control device. At the end of the treatment, there was a statistically significant decrease in the time to clinical healing (86 +/- 5.8 days in the active-treatment group compared with 114 +/- 10.4 days in the control group) (p = 0.01) and also a significant decrease in the time to over-all (clinical and radiographic) healing (96 +/- 4.9 days in the active-treatment group compared with 154 +/- 13.7 days in the control group) (p = 0.0001). The patients' compliance with the use of the device was excellent, and there were no serious complications related to its use. This study confirms earlier animal and clinical studies that demonstrated the efficacy of low-intensity ultrasound stimulation in the acceleration of the normal fracture-repair process.