title: Use of knee magnetic resonance imaging by primary care physicians in patients aged 40 years and older.
abstract: BACKGROUND
  Criteria are needed for primary care providers such that they can evaluate age-related knee pain in a cost-effective manner. This study examined (1) in what percentage of patients are appropriate radiographic views of the knee ordered before magnetic resonance imaging (MRI) for knee pain, (2) specialists' retrospective evaluation for appropriate utilization of MRI in knee pain, and (3) in what manner would the MRIs have altered diagnosis and management of knee disorders.
  
  
  OBJECTIVE
  Primary care providers underuse appropriate radiographs-especially, flexion weightbearing posteroanterior films-and overuse MRIs when evaluating older patients with knee pain.
  
  
  METHODS
  Case control.
  
  
  METHODS
  The authors performed a retrospective analysis of 100 patients older than 40 years with knee MRIs. Patient encounters with primary care physicians were reviewed. Given available information, specialists then formulated a pre- and post-MRI diagnosis and treatment plan and indicated whether the MRI would have altered their treatment.
  
  
  RESULTS
  Only 12 of 100 MRIs would have been ordered by an orthopaedist given the documented data. No MRIs would have been ordered in the 19 patients aged 60 years or older. Among 44 radiographs ordered, only 7 were flexion weightbearing. The most common pre-MRI diagnoses made by primary care providers were joint pain (22%) and meniscus injury (24%); the most common post-MRI diagnoses were osteoarthritis (40%) and degenerative meniscus injury (23%). In contrast, the 2 most common pre- and post-MRI diagnoses by specialists were osteoarthritis (28% and 37%, respectively) and degenerative meniscus injury (23% and 24%, respectively). Also, referrals to specialists increased from 9% pre-MRI to 76% post-MRI.
  
  
  CONCLUSIONS
  Primary care providers may be overusing knee MRIs and underusing flexion weightbearing posteroanterior radiographs in patients older than 40 years with knee pain.
  
  
  CONCLUSIONS
  Primary care providers should strongly consider not ordering knee MRI in patients with radiographic evidence of degenerative changes.
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: David J
authors.initials: DJ
authors.lastname: Petron
authors.forename: Patrick E
authors.initials: PE
authors.lastname: Greis
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Aoki
authors.forename: Stuart
authors.initials: S
authors.lastname: Black
authors.forename: Derek
authors.initials: D
authors.lastname: Krete
authors.forename: Kinjal B
authors.initials: KB
authors.lastname: Sohagia
authors.forename: Robert
authors.initials: R
authors.lastname: Burks