Trends in knee magnetic resonance imaging

Med Care. 2003 May;41(5):687-92. doi: 10.1097/01.MLR.0000062705.24024.9F.


Objective: To assess trends in knee magnetic resonance imaging (MRI) use and accompanying management changes to determine whether indications for this test have changed over time.

Data sources: Large administrative database containing health care information for 587,010 people living in 1 state who were enrolled in the Medicare or Medicaid programs. They all had used health services during 3 consecutive years between 1991 to 1995.

Methods: We performed a retrospective cohort study examining the rates of lower extremity MRI in successive years and calculated the proportion of patients who were seen by a knee specialist or underwent knee surgery subsequent to the MRI.

Results: The annual rate of knee MRI was 1.4 per 1000 person-years in 1991 and increased by 140% to 3.4 per 1000 person-years by 1995 (P = 0.001). Approximately half of patients who underwent a knee MRI in 1991 had a diagnosis of internal derangement of the knee in the prior year; this figure dropped to 35% in 1995 (P < 0.001). The percentage of patients undergoing a knee MRI who had no record of any knee diagnosis in the prior year grew from 13% in 1991 to 33% in 1995 (P < 0.001). Over the 5 years of the study, the percentage of patients whose knee MRI was followed by specialist care or knee surgery decreased from 68% to 58%, a relative change of 15% (P < 0.005).

Conclusion: Knee MRI use increased sharply during the study period, but the proportion of such patients who had a prior diagnosis of internal derangement or subsequently saw a knee specialist or underwent knee surgery decreased. This finding indicates that the criteria for knee MRI appear to have broadened substantially during this period.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Cohort Studies
  • Female
  • Humans
  • Knee / pathology*
  • Knee / surgery
  • Knee Joint / pathology
  • Knee Joint / surgery
  • Magnetic Resonance Imaging / statistics & numerical data*
  • Male
  • Medicaid
  • Medicare
  • Middle Aged
  • New Jersey
  • Retrospective Studies
  • Technology Assessment, Biomedical
  • United States
  • Utilization Review