title: Heal rate of metatarsal fractures: A propensity-matching study of patients treated with low-intensity pulsed ultrasound (LIPUS) vs. surgical and other treatments.
abstract: BACKGROUND
  Whether to treat metatarsal fractures conservatively or surgically is controversial. We test a hypothesis that metatarsal fractures treated conservatively with non-invasive low-intensity pulsed ultrasound (LIPUS) obtain heal rates comparable to current surgical techniques.
  
  
  METHODS
  This is a retrospective observational cohort study, using patient outcomes from a prospectively-collected LIPUS registry required by the U.S. Food & Drug Administration. Registry data were collected over a 5-year period and were reviewed and validated by a registered nurse. Data required for analysis were days-to-treatment (DTT) with LIPUS and a dichotomous outcome of healed versus failed, as assessed by clinical and radiographic criteria. Registry patients (DTT<365days) were propensity-matched to metatarsal fracture patients from a health claims database that includes medical and drug expenses for ∼90.1 million patients. The propensity match was based on patient demographic data (age, gender, body weight, fracture severity, and smoking status).
  
  
  RESULTS
  A total of 594 metatarsal fractures were treated with LIPUS, including 161 Jones fractures. Compared to patients in the claims database, LIPUS-treated patients were more likely to: be overweight or obese; be male; have open fracture; and smoke (all, P<0.0001), suggesting that these variables were perceived as nonunion risk factors by prescribing physicians. After propensity-matching, none of these differences between the registry and the health claims database remained significant. The heal rate with LIPUS treatment was 97.3%, comparable to the heal rate of 95.3% among claims patients in 2011 who did not receive LIPUS (P=0.0654). When fresh fractures (0-90days) and delayed unions (91-365days) were analyzed separately, the LIPUS fresh fracture heal rate was superior to claims patients (P=0.0381), and the delayed union heal rate was comparable. After exclusion of registry patients who received surgery, heal rate with LIPUS alone (97.4%) was significantly better (P<0.0097) than the heal rate for matched patients in 2011 (94.2%).
  
  
  CONCLUSIONS
  LIPUS significantly improved the heal rate of metatarsal fractures <1year old without surgery (P=0.0097). Metatarsal fractures treated with LIPUS alone have a heal rate comparable to fractures treated by surgical intervention.
authors.affiliation: Spaarne Gasthuis, Spaarnepoort 1, 2134 TM Hoofddorp, Netherlands. Electronic address: Peteranolte01@me.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Nolte
authors.affiliation: OrthoCarolina, 2001 Vail Ave, Suite 200B, Charlotte, NC 28207, United States. Electronic address: Drrba1@gmail.com.
authors.forename: Robert
authors.initials: R
authors.lastname: Anderson
authors.affiliation: Department of Orthopaedic Surgery, Mount Sinai School of Medicine, New York, NY, United States. Electronic address: Elton.strauss@mountsinai.org.
authors.forename: Elton
authors.initials: E
authors.lastname: Strauss
authors.affiliation: Department of Statistics, North Carolina State University, Raleigh, NC, United States. Electronic address: zwang28@ncsu.edu.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Statistics, North Carolina State University, Raleigh, NC, United States. Electronic address: lhu@ncsu.edu.
authors.forename: Liuyi
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Statistics, North Carolina State University, Raleigh, NC, United States. Electronic address: zxu13@ncsu.edu.
authors.forename: Zekun
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Bioventus LLC, Durham, NC 27703, United States. 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; D017102:Fracture Healing / Q000502:physiology*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008682:Metatarsal Bones / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D057216:Propensity Score; D012189:Retrospective Studies; D016896:Treatment Outcome; D014464:Ultrasonic Therapy
keywords: Jones fracture; Obesity; Open fracture; Tobacco smoking