title: PATTERNS OF ONSITE MAGNETIC RESONANCE IMAGING EQUIPMENT AMONG ORTHOPEDIC PRACTICES.
abstract: BACKGROUND
  Despite ongoing policy debate, little is known about the growth in orthopedic surgery practices with onsite magnetic resonance imaging (MRI) capacity, or practice characteristics associated with the acquisition of in-office MRI equipment.
  
  
  METHODS
  In July 2012, American Academy of Orthopaedic Surgeons (AAOS) member practices received a web-based survey requesting general information about their practice, such as number practice providers authorized to order MRIs, the type of onsite MRI capacity present (if any), and the date of acquisition for the MRI equipment. Survey responses were augmented with county-level measures of practice area characteristics as of the year of first onsite MRI acquisition (or 2012 for practices without an onsite MRI).
  
  
  RESULTS
  The survey obtained usable responses from 740 orthopedic practices, which were geographically representative of AAOS member practices. Forty percent (298) reported onsite MRI capacity. Onsite MRI acquisition occurred at a steady pace over 2000-2012, with no dramatic increase occurring in any particular year over that period. Multivariate logistic regression indicated that practice size (number of providers) was the most important factor affecting the likelihood of onsite MRI acquisition. There was no association between onsite MRI acquisition and any of the county-level practice area characteristics included in the analysis.
  
  
  CONCLUSIONS
  Orthopedic practices acquiring onsite MRI equipment on average are much larger than practices without onsite MRI capacity. Larger practices may be more likely to attain the economies of scale necessary to absorb the fixed costs associated with onsite MRI acquisition.
authors.affiliation: Health Policy & Management,Texas A&M Universityrohsfeldt@srph.tamhsc.edu.
authors.forename: Robert
authors.initials: R
authors.lastname: Ohsfeldt
authors.affiliation: General Internal Medicine,University of Pennsylvania.
authors.forename: Pengxiang
authors.initials: P
authors.lastname: Li
authors.affiliation: Avalon Health Economics.
authors.forename: John
authors.initials: J
authors.lastname: Schneider
mesh_terms: D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D009985:Orthopedics / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*
keywords: Advanced imaging; Economies of scale; Stark exemption; Technology diffusion