Reliability of Knee MRIs

MRIs – Useful or Useless for Knee Pain?

I often receive emails from prospective patients who have an X-ray or MRI they want to send us. Sometimes they want an opinion to back up a surgical recommendation; sometimes they want an opinion to support their desire to avoid surgery. In either case, when I tell them that the X-ray or MRI may not be telling the truth about their pain source, they become surprised and confused.
New findings say that many MRIs are useless. Investigators examined patients who had had an MRI for knee pain to determine whether the MRI was helpful in determining the final outcome of treatment.

An April 2022 study (1) questioned whether there is a problem of over diagnosis and subsequent overutilization of total knee arthroplasty (replacement). The study noted that medical insurance companies have questions about the over exaggeration of radiographic (MRI) findings and subsequent overutilization of total knee arthroplasty. Currently, the standard of care for assessing potential knee arthroplasty candidates includes assigning a Kellgren-Lawrence (KL) radiographic score. This study investigated the accuracy of reported preoperative Kellgren-Lawrence (KL) radiographic score scores in patients undergoing total knee arthroplasty.

  • Records of 277 patients who had underwent total knee arthroplasty were randomly selected from a large patient data registry and retrospectively reviewed.
  • Two blinded raters assigned Kellgren-Lawrence (KL) radiographic scores to the radiographs obtained during the preoperative assessment, which were compared to the scores reported by the operative surgeon.
  • Between blinded raters a good MRI reliability was found. Raters fully agreed on the KL classification for 196 patients (70.76%). Compared with blinded raters, the operative surgeon assigned lower KL scores.
  • “Reporting of KL score is consistent between operative surgeons and independent reviewers. In cases of disagreement between reviewers, the operative surgeon was generally more conservative in their estimation of the extent of osteoarthritis present radiographically. Concerns regarding inflation of radiographic findings to support surgical preauthorization are unwarranted.”


A December 2021 paper (2) assessed the diagnostic accuracy of knee ultrasound for evaluation of meniscus and collateral ligaments pathology in comparison with MRI. The researchers write: “Although magnetic resonance imaging (MRI) is often the “gold standard” for diagnosing knee problems, it has many limitations. Therefore, ultrasonography has been suggested as an effective rapid alternative in many knee abnormalities, especially after injuries of the meniscus and collateral ligaments.”

The researchers found:

  • Ultrasound compared to MRI for the assessment and diagnosing of meniscus injuries overall accuracy (91.7% vs. 88.3%).
  • Ultrasound compared to MRI for the assessment and diagnosing collateral ligament injures overall accuracy (96.7% vs. 93.3%).

The researchers concluded: “Ultrasonography is a useful screening tool for the initial diagnosis of meniscal and collateral ligament pathology compared to or even with potential advantages over MRI, especially when MRI is unavailable or contraindicated.”

1 Gregory JJ, Ziarati P, Werth PM, Jevsevar DS. Do Physicians Overestimate Radiographic Findings in Patients Undergoing Knee Arthroplasty?. Arthroplasty today. 2022 Jun 1;15:98-101.
2 Elshimy A, Osman AM, Awad ME, Abdel Aziz MM. Diagnostic accuracy of point-of-care knee ultrasound for evaluation of meniscus and collateral ligaments pathology in comparison with MRI. Acta Radiologica. 2021 Dec 1:02841851211058280.


Do You Have Questions? Ask Dr. Darrow

Most Popular
Skip to content