Study: Ultrasound technique can speed delayed bone healing

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Low-intensity pulsed ultrasound (LIPUS) treatment can result in significantly greater acceleration toward bone healing for patients with inadequate or delayed bone union, according to a study published online Oct. 7 in BMC Musculoskeletal Disorders.

Markus D. Schofer, MD, of the department of orthopedics at the University Hospital Marburg in Marburg, Germany, and his colleagues noted that while prior studies have shown that LIPUS is a noninvasive treatment option that can enhance the healing of fresh closed tibial fractures, “the specific mechanism of action of LIPUS on the bone healing process remained uncertain and a matter of intense speculation, discussion and debate.”

The researchers sought to compare the healing response of tibial delayed unions between individuals treated with LIPUS and subjects treated with an inactive sham device.

Adult patients who had sustained a tibial shaft fracture that subsequently showed inadequate progress toward healing (defined as a lack of clinical and radiologic evidence of union, bony continuity or bone reaction at the fracture site for no less than 16 weeks from the index injury or the most recent intervention) at six hospitals in Germany were enrolled in the study. Schofer and colleagues divided patients into two groups at random to receive either LIPUS (51 patients) or an identical nonoperative sham device (50 patients). Both study personnel and participants were blinded to random treatment assignment throughout the study.

Each patient was instructed to use their assigned device for 20 minutes per day for a period of 16 weeks, and the individuals who were a randomly assigned to the active treatment had the ultrasound pressure wave signal set at 1.5 MHz frequency, 1 kHz repetition rate, 200 us pulse duration and 30 mW/cm2 spatial intensity.

Progress toward healing was estimated from changes in bone mineral density (BMD) and gap area as determined from CT scans, the authors explained. In addition to CT scans, radiographs also were taken at one-, two- and three-month follow-up intervals. Blinded study physicians were asked to judge the healing status of each study subject at 16 weeks.

Schofer and colleagues determined that overall compliance with the treatment regimen was approximately 91 percent, with an average total time of device usage of 2,040 minutes out of a possible 2,240 minutes.

The average improvement in BMD was 1.34 times greater for LIPUS-treated subjects (34 percent greater BMD) when compared to the sham treatment and an average reduction in bone gap area also favored LIPUS treatment. Additionally, 65 percent of LIPUS and 46 percent of sham subjects were judged to be healed after 16 weeks by the study physicians, wrote the authors.

“These findings demonstrate significantly greater progress toward bone healing after LIPUS treatment compared to no LIPUS treatment in subjects with established delayed unions of the tibia,” said Schofer.  As a result, LIPUS may offer a cost-effective addition to conservative or operative management of delayed bone fracture healing, the study concluded.