Summary

The perception of a "pop" during a knee injury is a moderately predictive clinical indicator of a medial meniscal root tear and should be routinely inquired about while taking patient history.

Abstract

Purpose

Meniscal root tears change the biomechanics and kinematics of the knee leading to accelerated joint degeneration. Surgical intervention is indicated to repair these tears and restore biomechanics leading to better clinical and radiological outcomes. Accurate clinical diagnostic criteria for the presence of a meniscal root tear are not well established. This study aimed to evaluate the accuracy, sensitivity, specificity, and predictive values of hearing or feeling a “pop” for identifying isolated meniscal root tears.

Methods

This was a retrospective analysis of medical records of consecutive patients who underwent meniscal repair for isolated meniscal tears at our institution between January 2015 and June 2024. Exclusion criteria were previous ipsilateral knee surgery, fracture, or tumor. Demographic data, including sex, body mass index (BMI), ASA status, diabetes and smoking history, report of a “pop” heard or felt and type of tear as visualized during knee arthroscopy.

Accuracy, sensitivity, specificity, positive predictive value (ppv) and negative predictive value (npv) of perceiving a pop for a posterior root tear of the medial meniscus were calculated. Potential demographic differences were assessed with student t-test, chi-squared, and Fischer Exact test. All analysis was done in python 3.10.0 with statsmodel 0.14.2 and scipy.stats 1.12.0.

Results

This analysis included a hundred knees of ninety-five patients who underwent an isolated meniscus repair. Twenty-eight of these patients reported hearing or feeling a pop at the time of injury. Of these, 17 had medial meniscal root tears. The positive predictive value of having an isolated medial meniscus root tear after a perceived pop at the injury was 61%, the negative predictive value was 69%, the sensitivity was 44%, the specificity was 82% and the diagnostic accuracy was 67%. BMI is the only demographic difference between patients who reported a pop and those who did not perceive a pop (0.004), but there was no significant difference in BMI amongst patients with a medial meniscus root tear reporting a pop and not reporting a pop (0.180). All other demographic characteristics did not show any significant difference.

Conclusion

This study found that the perception of a "pop" during a knee injury is a moderately predictive clinical indicator of a medial meniscal root tear and should be routinely inquired about while taking patient history.