ISAKOS Congress 2021

2021 ISAKOS Biennial Congress ePoster


Inter-Rater Reliability Of The Classification Of The J-Sign Is Inadequate Amongst Experts

Laurie A. Hiemstra, MD, PhD, FRCSC, Dead Man's Flats, AB CANADA
Brendan Sheehan, MD, FRCSC, Dip. Sport Med, St. John , New Brunswick CANADA
Treny M Sasyniuk, MSc, Vancouver, British Columbia CANADA
Sarah Kerslake, BPhty, MSc, Banff, Alberta CANADA

Banff Sport Medicine Foundation, Banff, Alberta, CANADA

FDA Status Not Applicable


Individual raters demonstrated a consistent standard for assessing the J-sign, but these standards were not reliable between assessors for subjects with recurrent patellofemoral instability.

ePosters will be available shortly before Congress



The purpose of this study was to determine the inter- and intra-rater reliability of the symmetry, classification, and underlying pathoanatomy associated with the J-sign using video recordings of knees in subjects with recurrent lateral patellofemoral instability.


In this blinded, inter-rater reliability study, 30 patellofemoral joint experts independently assessed 30 video recordings of the knees of patients with recurrent lateral patellofemoral instability performing the J-sign test. Raters documented J-sign symmetry, and graded it according to the quadrant and Donell classifications. Raters indicated the most significant underlying pathoanatomy, and presence of sagittal plane mal-tracking. Intra-rater reliability was assessed by a test-retest with four raters repeating the assessments 2-weeks apart. Mean pairwise simple and/or weighted Cohen’s kappa were performed to measure inter- and intra-rater reliability, as well as calculation of percent agreement.


J-sign symmetry demonstrated fair inter-rater reliability (k=0.26), while intra-rater reliability was moderate (k=0.48). Inter-rater reliability for the quadrant and Donell classifications indicated moderate agreement, k=0.51 and k=0.49 respectively; while intra-rater reliability was k=0.79 and k=0.72, indicating substantial agreement. Inter-rater reliability of the foremost underlying pathoanatomy produced only slight agreement (k=0.20), however intra-rater reliability was substantial (k=0.68). Sagittal plane mal-tracking demonstrated slight inter-rater (k=0.23) but substantial intra-rater agreement (k=0.64).


The symmetry, classification, and underlying pathoanatomy of the J-sign demonstrated fair to moderate inter-rater reliability, and moderate to substantial intra-rater reliability among expert reviewers using video recordings of recurrent lateral patellofemoral instability patients. These findings suggest individual raters have a consistent standard for assessing the J-sign, but that these standards are not reliable between assessors.

Level of Evidence: III

Key Words: J-sign, patellar instability; patellofemoral instability; patellar dislocation; patellar tracking;

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