MRI for knee injuries and nonspecific knee problems

Findings by SBU Alert

Version: 1

Technology and target group

Knee injury and nonspecific knee problems are common and often lead to work impairment. The exact size of the target group is unknown. Mainly, clinical examination and the patients medical record are used to diagnose knee injuries or nonspecific knee problems. Also, x-ray examination is often used and can reveal possible skeletal changes. Magnetic resonance imaging (MRI) and arthroscopy (laparoscopic examination) are used to detect injuries or other changes in the soft tissues, ligaments, joint capsule, or the articular cartilage of the knee. The advantage of MRI is that it is noninvasive. The advantage of arthroscopy is that it allows treatment to be performed on problems observed in the joint on the same occasion as when the diagnostic examination is carried out. A current clinical question is whether or not it would be an effective strategy to initially perform MRI for knee injuries or joint problems and thereafter determine whether or not arthroscopy should be carried out.

Patient benefits

The diagnostic characteristics of MRI for knee problems have been analyzed in several studies that involved arthroscopy as a reference. MRI could identify approximately 80% of the changes that were diagnosed by arthroscopy. Furthermore, MRI made it possible to exclude approximately 90% of the cases that had been excluded by arthroscopy. It was found that the initial use of MRI could avoid the use of arthroscopy and thereby save the patient from discomfort and the risk for complications.

Economic aspects

Studies from the United States have shown that the costs for MRI are offset by the reduced need for arthroscopy. Performing the same analysis, but using Swedish cost data, shows a cost increase of 25%.

Scientific evidence

There is good* scientific documentation on the characteristics of MRI in diagnosing the knee in studies where arthroscopy is used as a reference. There is poor* scientific documentation addressing the cost effectiveness of the method.

Initial MRI appears to be a cost-effective strategy in diagnosing knee injury and nonspecific knee problems since unnecessary interventions can be avoided. The cost difference between MRI and arthroscopy in Sweden is not great enough to draw a general conclusion that initial MRI should be performed. Hence, the first step is to identify indications where such a strategy would be expected to provide the greatest benefit. Since the studies reviewed do not clarify what indications should be selected, it is essential to conduct well design studies to clarify this issue. Likewise, it is essential to conduct Swedish economic assessments that consider both the sacrifices by patients and the resource expenditures in healthcare.

*This assessment by SBU Alert uses a 4-point scale to grade the quality and evidence of the scientific documentation. The grades indicate: (1) good, (2) moderate, (3) poor, or (4) no scientific evidence on the subject.

This summary is based on a report prepared at SBU in collaboration with Prof Kjell Jonsson, MD, PhD, Lund University Hospital, and Prof Em Jan Gillquist, MD PhD, Linköping, and has been reviewed by Assoc Prof Jon Karlsson, MD PhD, Sahlgrenska University Hospital.

The full report is available only in Swedish.

Alert is a joint effort by the Swedish Council on Technology Assessment in Health Care (SBU), the Medical Products Agency, the National Board of Health and Welfare, and the Federation of Swedish County Councils.

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