Nuclear medicine

The study find that the John Vairo, clinical associate professor of kinesiology, orthopedics and rehabilitation, said that ideally, a person’s kneecap will align with the midline of the leg neither too far to the left or the right. A greater TT-TG distance may suggest that the kneecap is off center and therefore more likely to slip out of the joint.

A greater TT-TG distance

Vairo said the study  recently published in Clinical Orthopaedics and Related Research ; may help clinicians refine how they use the measurement in their practice. They find that once this measurement reaches 13 millimeters; that individual may be more likely to experience problems with kneecap dislocation. That being says; it’s also not the only thing that should be taken into account if a surgeon is considering more aggressive; types of treatment like surgery to decrease this distance; which requires significant recovery time.”

John Vairo; clinical associate professor of kinesiology, Penn State According to the researchers; issues with kneecap stability are common; especially among women or people who engage in sports. They said it may not pose an issue for people who are not physically active; but more aggressive treatment like surgery  may be require for athletes. Vairo says that while clinicians are using TT-TG distance to predict kneecap instability previousl;, best practices were unclear.

More aggressive treatment

He said that computed tomography (CT) scans have been most commonly use in the past; but some studies have suggest that TT-TG distances are measure differently depending on if a CT or MRI scan is done. “A novelty to our study is that we want to test the reliability of this measurement using MRI in a setting that was more true to how it would be used in current day-to-day clinical settings,” Vairo said.

“This routinely consists of the measurement being performed one time; often by a surgeon who may be considering surgery.” The researchers use medical records from 131 patients 48 who had confirm cases of kneecap dislocation and 83 controls with meniscal tears. Three clinicians with various levels of experience used the patients’ MRI scans to measure TT-TG distance without knowing their diagnosis beforehand.

Clinicians  regardless of experience

After analyzing the data; the researchers found that all three clinicians  regardless of experience  were able to reliably and precisely measure TT-TG distance. They also found that TT-TG distance tend to be greater in patients with kneecap instability. “A TT-TG distance of 13 mm was found ;two times more frequently in individuals that truly do have this condition than those who don’t;” Vairo said.

“At the same time, there were individuals with this condition who had measurements smaller than 13 mm; driving home the importance of knowing the details associated with different imaging techniques and being aware of other contributing factors to instability. Our paper proposes that using specific MRI scans in a standardized fashion may help produce more accurate readings of this measurement.”