title: Treatment of chronic (>1 year) fracture nonunion: heal rate in a cohort of 767 patients treated with low-intensity pulsed ultrasound (LIPUS).
abstract: BACKGROUND
  Established fracture nonunions rarely heal without secondary intervention. Revision surgery is the most common intervention, though non-surgical options for nonunion would be useful if they could overcome nonunion risk factors. Our hypothesis is that low-intensity pulsed ultrasound (LIPUS) can enhance heal rate (HR) in fractures that remain nonunion after one year, relative to the expected HR in the absence of treatment, which is expected to be negligible.
  
  
  METHODS
  We collated outcomes from a prospective patient registry required by the U.S. Food & Drug Administration. Patient data were collected over a 4-year period beginning in 1994 and were individually reviewed and validated by a registered nurse. Patients were only included if they had four data points available: date when fracture occurred; date when LIPUS treatment began; date when LIPUS treatment ended; and a dichotomous outcome of healed vs. failed, assessed by clinical and radiological criteria. Data were used to calculate two derived variables: days to treatment (DTT) with LIPUS, and days on treatment (DOT) with LIPUS. Every validated chronic nonunion patient (DTT>365 days) with complete data is reported.
  
  
  RESULTS
  Heal rate for chronic nonunion patients (N=767) treated with LIPUS was 86.2%. Heal rate was 82.7% among 98 patients with chronic nonunion ≥5 years duration, and 12 patients healed after chronic nonunion >10 years (HR=63.2%). There was more patient loss to follow-up, non-compliance, and withdrawal, comparing chronic nonunion patients to all other patients (p<0.0001). Patient age was the only factor associated with failure to heal among chronic nonunions (p<0.004). Chronic nonunion patients averaged 3.1 surgical procedures prior to LIPUS, but some LIPUS-treated patients were able to heal without revision surgery. Among 91 patients who received LIPUS ≥90 days after their last surgery, HR averaged 85.7%, and the time from last surgery to index use of LIPUS averaged 449.6 days.
  
  
  CONCLUSIONS
  Low-intensity pulsed ultrasound enhanced HR among fractures that had been nonunion for at least 1 year, and even healed fractures that had been nonunion >10 years. LIPUS resulted in successful healing in the majority of nonunions without further surgical intervention.
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA. Electronic address: Robert.Zura@duke.edu.
authors.forename: Robert
authors.initials: R
authors.lastname: Zura
authors.affiliation: Department of Orthopaedic Surgery, University of Missouri, Columbia, MO, USA. Electronic address: dellaroccag@health.missouri.edu.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Della Rocca
authors.affiliation: Department of Orthopaedic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA, USA. Electronic address: Samir.Mehta@uphs.upenn.edu.
authors.forename: Samir
authors.initials: S
authors.lastname: Mehta
authors.affiliation: Bioventus LLC, Amsterdam, Netherlands. Electronic address: Andrew.Harrison@bioventusglobal.com.
authors.forename: Andrew
authors.initials: A
authors.lastname: Harrison
authors.affiliation: Bioventus LLC, Durham, NC 27703, USA. Electronic address: Chris.Brodie@bioventusglobal.com.
authors.forename: Chris
authors.initials: C
authors.lastname: Brodie
authors.affiliation: Bioventus LLC, Durham, NC 27703, USA. Electronic address: John.Jones@bioventusglobal.com.
authors.forename: John
authors.initials: J
authors.lastname: Jones
authors.affiliation: Bioventus LLC, Durham, NC 27703, USA. Electronic address: Grant.Steen@bioventusglobal.com.
authors.forename: R Grant
authors.initials: RG
authors.lastname: Steen
mesh_terms: D000328:Adult; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods; D017102:Fracture Healing; D050723:Fractures, Bone / Q000503:physiopathology / Q000628:therapy*; D005599:Fractures, Ununited / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods
keywords: Age; Delayed union; Obesity; Recalcitrant nonunion; Smoking; Treatment-resistant nonunion