Surgeons are familiar with treating fracture nonunion with a variety of external fields, such as electrical stimulation and low-intensity ultrasound1. However, a major weakness in the literature is a lack of studies that directly compare these noninvasive techniques with surgical stabilization with or without grafting. Most surgeons in the United States will not be familiar with higher-intensity-ultrasound extracorporeal shock-wave therapy for treating nonunion, since it is FDA-approved in the musculoskeletal system for only the treatment of chronic heel pain and lateral epicondylitis2,3. Clinical studies from Europe and elsewhere have suggested that extracorporeal shock-wave therapy effectively heals nonunions in a high percentage of patients, particularly those with a hypertrophic nonunion4-6. Just as is the case with studies of other external fields for treating fracture nonunions, extracorporeal shock-wave therapy has not previously been directly compared with surgical treatment.
In their randomized controlled trial, Cacchio et al. found that extracorporeal shock-wave therapy was as effective as surgery for healing fracture nonunion. At six months after treatment, more than 70% of nonunions in patients treated with extracorporeal shock-wave therapy had healed, which was similar to the result in the surgical group, and, in both extracorporeal shock-wave groups, more than 90% of nonunions in enrolled patients were healed by two years. The strength of this study, in addition to the randomized design, was the fact that the radiographic outcomes were assessed by radiologists not directly involved with other aspects of the study and that these assessments were found to be reliable and reproducible. Patients were not enrolled unless their radiographs, which were assessed by two independent radiologists, had failed to demonstrate progress toward union for at least six months following treatment. This increases confidence that the majority of the nonunions would not have healed without intervention and decreases the concern about the lack of an untreated control group.
Interestingly, the data also showed that the patients who received extracorporeal shock-wave therapy had quicker relief of pain and return to function than the surgical patients had, as reflected by significantly better pain and function scores at three and six months after treatment. These early differences were not seen at twelve and twenty-four months because the pain decreased and function improved in the surgically treated patients. It is unlikely that this finding is explained by earlier healing in the extracorporeal shock-wave therapy groups, and the authors suggest that it might be from a direct effect of extracorporeal shock-wave therapy on pain mechanisms. If these results were to hold true in other studies, better pain relief and improved function in the early months after treatment would be important advantages of treating fracture nonunion with extracorporeal shock-wave therapy.
This study was only powered to detect a 30% healing-rate difference between groups. A much smaller difference than this would be clinically significant. However, the near equivalence between groups at all three time points in this study and a nearly 95% healing rate at two years in the extracorporeal shock-wave therapy group that received an energy flux density of 0.40 mJ/mm2 decrease the concern about lack of power to detect important differences. The authors acknowledged that the healing assessments by the radiologists were not completely blinded, since changes in hardware and other postoperative changes that would be visible on radiographs would identify many of the patients in the surgical group.
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. There are important disadvantages to the extracorporeal shock-wave therapy protocol as it was applied in this study. The authors enrolled patients with atrophic nonunions, but the large number lost to follow-up and the failures in the extracorporeal shock-wave therapy groups, combined with previous reports in the literature, suggest that extracorporeal shock-wave therapy is not very effective for the treatment of an atrophic nonunion. Similar to the result of treatment with other noninvasive techniques, malalignment is not corrected, making the extracorporeal shock-wave technique most applicable only for patients with a well-aligned nonunion. Patients with infection or broken hardware were not enrolled. Finally, the extracorporeal shock-wave therapy treatment was intensive in several ways. There were four extracorporeal shock-wave therapy treatments over four weeks, each requiring the use of regional anesthesia. 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."
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. Patients with a history of infection, poor quality of local soft tissues, and appreciable medical comorbidities would be particularly good candidates. Further study might identify effective but less intensive treatment protocols for extracorporeal shock-wave therapy. For instance, a minimally invasive surgical stabilization technique could be combined with extracorporeal shock-wave therapy to achieve union with earlier function and without the need for the immobilization used in this study.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.
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