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Shock waves could help long bones mend that aren't healing on their own, according to a study published in the November issue of The Journal of Bone and Joint Surgery.

Doctors at two university hospitals in Italy, led by Angelo Cacchio, M.D., found that applying extracorporeal shock wave therapy to a type of non-healing fracture called nonunions resulted in healing rates as good as interventional surgery, the standard treatment.

When radiological slides were examined six months after treatment, around 70 percent of patients in both groups had healed: both those who had surgeries to repair the bone and those who merely received four sessions of 4,000 shock wave pulses to the shattered limb.

Interestingly, patients who received shock waves, but not surgery, were somewhat more likely to have less pain and better limb function the first three and six months following treatment, though the differences between the two groups vanished within a year or two.

Although other studies have suggested that shock wave therapy can be useful in bone healing, the doctors aren't sure how it works. They speculate that the pulses could bring pain relief by overstimulating the nerves, thereby raising the patient's pain threshold. And they could promote bone growth by "creating micro-fractures that induce a healing reaction and increased vascularity, as occurs during the natural bone-healing process," the doctors write.

The study, which investigated 126 patients divided into several treatment groups, and conducted at two Rome university hospitals, the "San Salvatore" Hospital of L'Aquila and "La Sapienza" University, had several design limitations. An ethics committee refused to allow a control group, which would have received no treatment, and the study was not completely blind, as radiologists examining the slides could potentially recognize which patients belonged to the surgical groups by tell-tale marks on the bone or the movement of hardware. Also, those with misaligned fractures were excluded from the study.

In an accompanying editorial, J. Lawrence Marsh, M.D., a doctor at the University of Iowa Hospitals and Clinics in Iowa City, Iowa, wonders how applicable the treatment will be in clinical practice.

"More important than concerns about the study design is uncertainty of how these results will generalize to other practice environments, assuming that extracorporeal shock wave therapy were made more widely available for the treatment of nonunion," he writes.

Although he acknowledges the study's success, he suggests that shock wave treatment is rather intensive. "There were four extracorporeal shock wave therapy treatments over four weeks, each requiring the use of regional anesthesia," he notes. "All fractured limbs were immobilized for six to twelve weeks and, if the nonunion was in a lower extremity, a long leg cast was applied. Many surgeons would argue, and at least some patients would agree, that this intensive treatment program should not be considered 'conservative'."

Another fact to consider for a future study was the difference in enrollment rates for those with hypertrophic nonunions and atrophic ones. Hypertrophic breaks, although non-healing, have calluses, and are vascular enough for new bone growth, while atrophic fractures usually feature some sort of blood supply impairment, and often require grafts to heal. Drop out among atrophic patients in the study was high: 32 percent quit before therapy was over, compared with only 4 percent in the hypertrophic group.

Nonetheless, Dr. Marsh finds the results largely encouraging. "Despite these disadvantages, for selected patients with a nonunion, a nonoperative treatment option that results in similar healing time, faster return to function, and quicker relief of pain than what can be expected after surgery would be a welcome addition," he writes.