A cohort study of 4,190 patients treated with low-intensity pulsed ultrasound (LIPUS): findings in the elderly versus all patients

Abstract

BackgroundPatient age is one of many potential risk factors for fracture nonunion. Our hypothesis is that older patients (≥60) with fracture risk factors treated with low-intensity pulsed ultrasound (LIPUS) have similar heal rate (HR) to the population as a whole. We evaluate the impact of age in conjunction with other risk factors on HR in LIPUS-treated patients with fresh fracture (≤90 days old).MethodsThe Exogen Bone Healing System is a LIPUS device approved in 1994 to accelerate healing of fresh fracture. After approval, the FDA required a Post-Market Registry to assess performance. Patient data collected from October 1994 until October 1998 were individually reviewed and validated by a registered nurse. Four distinct data elements were required to report a patient: date fracture occurred; date treatment began; date treatment ended; and a dichotomous outcome of healed v. failed, by clinical and radiological criteria. Data were used to calculate two derived variables; days to treatment (DTT) and days on treatment (DOT). Every validated fresh fracture patient with DTT, DOT, and outcome is reported.ResultsThe validated registry had 5,765 patients with fresh fracture; 73% (N = 4,190) are reported, while 13% of patients were lost to follow-up, 11% withdrew or were non-compliant, and 3% died or are missing outcome. Among treatment-compliant patients, HR was 96.2%. Logistic estimates of the odds ratio for healing are equivalent for patients age 30 to 79 years and all age cohorts had a HR > 94%. Open fracture, current smoking, diabetes, vascular insufficiency, osteoporosis, cancer, rheumatoid arthritis, and prescription NSAIDs all reduced HR, but older patients (≥60) had similar HRs to the population as a whole. DTT was significantly shorter for patients who healed (p < 0.0001).ConclusionsComorbid conditions in conjunction with aging can reduce fracture HR. Patients with fracture who used LIPUS had a 96% HR, whereas the expected HR averages 93%. Time to treatment was significantly shorter among patients who healed (p < 0.0001), suggesting that it is beneficial to begin LIPUS treatment early. Older patients (≥60) with fracture risk factors treated with LIPUS exhibit similar heal rates to the population as a whole.

Treatment of chronic (>1 year) fracture nonunion: Heal rate in a cohort of 767 patients treated with low-intensity pulsed ultrasound (LIPUS)

“…Heal rate (HR) in an acutefracture cohort of patients treated with LIPUS has been reported [21], and we use similar methods here.…”

“…This study was formally exempted from ethical approval by the Institutional Review Board of the lead author's institution [21] because data were drawn from a post-market registry meant to satisfy FDA reporting requirements. Heal rate (HR) in an acutefracture cohort of patients treated with LIPUS has been reported [21], and we use similar methods here.…”

“…Registry data for the period from 14 Oct 1994 until 15 Oct 1998 were validated by a registered nurse who manually compared every patient's paper record to the digital record [21]. To be analyzed, each patient was required to have four data points [21]: Clinically solid and free of pain on manual stress At least three of four cortices bridged on X-ray views These data were used to calculate 2 derived variables of interest [21]:…”

“…To be analyzed, each patient was required to have four data points [21]: Clinically solid and free of pain on manual stress At least three of four cortices bridged on X-ray views These data were used to calculate 2 derived variables of interest [21]:…”

“…The study population was drawn from a validated, FDA-required post-market registry of consecutive patients who used the Exogen device, with data published in part previously [19][20][21]. Our hypothesis is that low-intensity pulsed ultrasound (LIPUS) can induce healing in chronic nonunion fractures.…”