Greatest pain comes four hours after MR arthrogram injection

Dec 25, 2008

Researchers in Switzerland have found that patients who undergo MR arthrography temporarily experience the most pain in the affected joints four hours after injection.

The study, from the Orthopedic University Hospital Balgrist in Zurich, also showed that the pain is most pronounced in patients 30 years of age and younger, but the discomfort for virtually all patients disappears after one week.

While such pain depends, in part, on a patient's age, researchers found that the type of joint, injected volume, gender, and radiologist experience did not significantly affect pain levels.

MR arthrography is used in diagnosing rotator cuff tear differentiation; detecting intra-articular loose bodies; postoperative evaluation of the knees, especially after meniscal tear repair; and characterizing ligament injuries of the elbow and ankle.

'Anxiety and pain'

"MR arthrography may also improve the detection of articular cartilage defects," said study co-author Dr. Nadja Saupe during her presentation of the research results at the RSNA annual meeting in Chicago. "However, intra-articular injection of contrast material may be associated with patient anxiety and pain."

The study included 1,085 patients, with a mean age of 46.2 years, ranging from 16 to 82 years. There were 611 females and 474 males. A total of 1,011 patients received 2 mmol/L of gadopentetate in the shoulder (675 patients), elbow (11 patients), hip (295 patients), knee (11 patients), or ankle (19 patients). The remaining 74 patients received 5 mmol/L of gadoterate in the wrist.

"Pain was assessed at four different time points -- directly after injection, four hours, one day [18 to 30 hours], and one week [six to eight days] after injection according to baseline," noted Saupe.

Patients were asked to rate their level of pain before the injection. Researchers used those answers as the baseline. Patients scored their pain on a scale of 0 to 10, with the lowest number as "no pain" and the highest number as "incredible pain." The study also evaluated potential pain factors such as time after injection, type of joint, volume of contrast agent, patient age, gender, and radiologist experience.

"When increased pain persisted at the end of the observation period," Saupe added, "additional assessment in order to exclude infections was done."

Four-hour mark

The analysis discovered that the "main pain increase [for all joints] was most pronounced four hours after injection," Saupe said. The pain was most pronounced in the hip (1.2 ± 1.7), followed by the elbow (1.1 ± 1.4) and the knee (1.0 ± 1.8). There was no significant difference between the different joints. One week after injection, patients' pain scores were back to the preinjection baseline.

The study also found a "significant interaction" between time and age. At four hours and at one day after injection, the highest pain scores were reported among patients younger than 30 years of age.

In addition, time was a dominant factor for the description of difference from baseline and pain. "The type of contrast, type of joint, volume of gadolinium containing contrast agent, gender, and type of physician were not significant," she said.

The study also found no signs of joint infection in the 1,083 patients who received complete follow-up examinations. Two patients were not available for follow-up interviews, while one patient with persistent pain after one week was referred to the orthopedic outpatient clinic. An examination and lab tests ruled out an infection.

Major side effects

No other major side effects, including anaphylactic reaction, cellulitis, or vascular complications were found among the patients in the study.

Seventy-six patients expressed minor reactions to the injection. The most common reactions were persistent pain (25%, 19 patients), pressure in the joint where the injection was given (20%, 15 patients), pain at the injection site (17%, 13 patients), pain at night (8%, six patients), headaches (5%, four patients), and aching muscles (5%, four patients).

With those results, the researchers concluded that patients experienced the greatest amount of minor pain four hours after MR arthrography, but that pain disappears after one week. "Such pain is more pronounced in patients below the age of 30 years," Saupe reiterated. "There is no significant relationship between pain score and radiologist experience."

The information from the study, she added, should be used to inform patients about the potential for their greatest discomfort four hours after injection, but also that mild pain should be gone after a maximum of one week.

Saupe also said that she would not recommend that patients exercise after injection, adding that such activity may have been the reason for the higher pain scores among patients 30 years and younger. "We thought most of the increased pain in the younger patients was because they are not afraid to work out after the injection, so I would not recommend [exercise]," she said.

By Wayne Forrest
AuntMinnie.com staff writer
December 26, 2008

MR arthrography study finds 'optimal injection site,' October 24, 2008

Making the most of MRI to assess the rotator cuff pre- and postinjury, November 9, 2007

MRI keeps pace with rapidly evolving musculoskeletal systems of young athletes, May 20, 2007

MR arthrography depicts tears, instability in triangular fibrocartilage complex, January 19, 2007