New Method for Assessing Knee Instability Risk

Impact of Knee Injuries

Knee injuries can lead to serious repercussions for individuals, particularly athletes, where such injuries may end careers. One common type of knee injury is knee instability, characterized by the knee’s tendency to twist or shift sideways during normal activities. Predicting the risk of this injury is challenging due to various contributing factors.

Previous Research on Knee Instability

Earlier studies employed a CT-based approach to assess the risk of knee instability, focusing on the distance between two anatomical landmarks around the knee joint: the tibial tubercle (TT) and the trochlear groove (TG). However, significant variability in TT-TG distance measurements was noted, depending on the measurement method used, highlighting the need for more objective assessment techniques.

Recent Study Utilizing MRI

Researchers from Penn State recently investigated an alternative approach using MRI to minimize subjectivity in measurements. The primary aim was to compare TT-TG distances between individuals with no reported knee injuries and those with knee instability.

Study Methodology and Findings

The study analyzed data from 131 patients, comprising 48 individuals with knee instability and 83 with cartilage tears but no bone involvement. Three independent orthopedic specialists, each with varying expertise, reviewed patient records from 2012 to 2016. The analysis revealed minimal variation in TT-TG distance among the specialists, with a 93% concordance rate for knee instability patients and over 95% for normal patients. This indicated that MRI-based measurements are more reliable than CT-based methods.

Threshold for Predicting Knee Instability Risk

The researchers established a threshold TT-TG distance of 13 mm for predicting knee instability risk, which improved diagnostic efficiency by 15%. Their findings indicated that a TT-TG distance greater than 13 mm was twice as prevalent in patients at high risk for knee instability. However, the research team cautioned against using this threshold alone for risk prediction, as some patients with distances exceeding 13 mm did not exhibit any knee instability.

Conclusion and Recommendations

The study suggests that TT-TG distance should be considered alongside other known factors influencing knee instability to enhance risk assessment accuracy.

Author Information

Written by Vinayak Khattar, Ph.D., M.B.A.

References

Vairo, Giampietro, et al. “Tibial Tubercle-Trochlear Groove Distance Is a Reliable and Accurate Indicator of Patellofemoral Instability.” Clinical Orthopaedics and Related Research, vol. 477, no. 6, June 2019, pp. 1450–58. insights.ovid.com, doi:10.1097/CORR.0000000000000711.
Press release: https://www.eurekalert.org/pub_releases/2019-07/ps-asm071719.php

Image by Dr. Manuel González Reyes from Pixabay.