Preoperative MRIs do not affect whether surgeons perform knee arthroscopy

However, more patients with an MRI report received treatments that varied from initial surgical plans.

Obtaining magnetic resonance imaging scans on patients waiting to undergo knee arthroscopy does not appear to affect whether patients actually receive surgery or improve outcomes, according to a prospective study by researchers in the United Kingdom.

"Provision of an MRI (magnetic resonance imaging) report for a group of experienced surgeons, after the decision to operate had been made and after a presurgery clinical assessment, had no effect on the proportion of patients who underwent arthroscopy," the study authors reported.

"An arthroscopy by a surgeon who was informed by an MRI report had no effect on patient outcome, although it did change planned management," they wrote.

Stephen Bridgman, FRCS(Ed), and colleagues conducted a randomized, controlled study to evaluate whether obtaining MRI reports on patients in the U.K. National Health Service (NHS) who were waiting for knee arthroscopy would reduce arthroscopy rates.

The study included 252 patients who averaged 43 years of age. All patients underwent MRI preoperatively by a blinded radiologist.

Before scheduling surgery, however, the orthopedic surgeon reviewed the patients' clinical notes and either a blank MRI report card or the completed MRI report card. They then decided whether surgery should proceed, according to the study, published in Arthroscopy.

"If they believed that arthroscopy was no longer indicated, they reviewed patients' cases to decide a new management plan," the authors noted.

Investigators randomly assigned 125 patients to the group with known MRI reports and 127 to the group with masked MRI reports. They found that seven of the 125 patients (5.6%) with known MRIs and eight of the 127 patients (6.3%) with masked MRIs did not undergo arthroscopy (P>.05).

"After an extensive series of multivariate analyses, no significant differences between groups were found in any secondary outcome measure. No complications were recorded in either group," the authors said.

However, provision of an MRI report did influence the planned treatment. More patients with known MRIs received treatments that were either completely or partially different from what was initially planned, according to the study.

Overall, surgeons had planned to perform a meniscectomy in 66% of patients both before and after MRI, but actually performed a meniscectomy in 49%. Also, surgeons had planned a washout either with or without debridement in 27% of patients before MRI and in 29% after MRI, but actually performed such procedures in 39%. Additionally, a plica resection was planned for 1% of patients before MRI, and was actually performed in 12%, according to the study.

Surgeons did not change their management plans in 98% of patients with masked MRIs and in 53% of patients with known MRIs. For the group with known MRIs, surgeons changed their treatment plans completely in 34 patients (27%) and partially in 25 patients (20%), the investigators reported.

"In most instances in which surgeons changed their management plans, this change was consistent with the findings of the MRI report," the authors wrote.

For more information:
Bridgman S, Richards PJ, Walley G, et al. The effect of magnetic resonance imaging scans on knee arthroscopy: A randomized controlled trial. Arthroscopy. 2007;23:1167-1173.