The Tibial Tubercle-Trochlear Groove Distance/Trochlear Dysplasia Index Quotient Is the Most Accurate Indicator for Determining Patellofemoral Instability Risk

Joaquin Moya-Angeler; Giampietro L Vairo; Dov A Bader; Wayne J Sebastianelli; Paul S Sherbondy

doi:10.1016/j.arthro.2021.08.018

The Tibial Tubercle-Trochlear Groove Distance/Trochlear Dysplasia Index Quotient Is the Most Accurate Indicator for Determining Patellofemoral Instability Risk

Arthroscopy. 2022 May;38(5):1608-1614. doi: 10.1016/j.arthro.2021.08.018. Epub 2021 Aug 25.

Authors

Joaquin Moya-Angeler¹, Giampietro L Vairo², Dov A Bader³, Wayne J Sebastianelli³, Paul S Sherbondy³

Affiliations

¹ Department of Orthopaedics & Rehabilitation, College of Medicine, The Pennsylvania State University, University Park, Pennsylvania, U.S.A.
² Departments of Kinesiology, and Orthopaedics and Rehabilitation, Colleges or Health and Human Development, and Medicine, The Pennsylvania State University, University Park, Pennsylvania, U.S.A.. Electronic address: glv103@psu.edu.
³ Department of Orthopaedics and Rehabilitation, College of Medicine, The Pennsylvania State University, University Park, Pennsylvania U.S.A.

PMID: 34450216
DOI: 10.1016/j.arthro.2021.08.018

Abstract

Purpose: The primary aim of our study was to evaluate diagnostic accuracy of the tibial tubercle-trochlear groove (TT-TG) distance relative to associated quotients produced from trochlear width (TT-TG distance/TW) and trochlear dysplasia index (TT-TG distance/TDI) for detecting patellofemoral instability. Secondary aims included identifying thresholds for risk and comparing differences between cases and controls.

Methods: Consecutive sampling of electronic medical records produced 48 (21 males, 27 females) patellofemoral instability cases (19 ± 7 years old) and 79 (61 males, 18 females) controls (23 ± 4 years old) who had a history of isolated meniscal lesion, as evaluated by magnetic resonance imaging. Standardized methods were employed with measurements executed in a blinded and randomized manner. A receiver operating characteristic curve assessed accuracy by area under the curve (AUC). The index of union (IU) was employed to identify a threshold for risk. Two-sample t-tests examined group differences. P < .05 denoted statistical significance.

Results: The AUC values were .69 (.60, .79) for TT-TG distance, .81 (.73, .88) for TT-TG distance/TW, and .85 (.78, .91) for TT-TG distance/TDI. Thresholds were 14.7 mm for TT-TG distance, .36 for TT-TG distance/TW, and 1.88 for TT-TG distance/TDI. Cases demonstrated statistically significant (P < .001) greater values for each measure compared with controls: TT-TG distance (15.8 ± 4.2 mm vs 12.9 ± 3.6 mm, [1.4, 4.3]); TT-TG distance/TW (.51 ± .24 vs .31 ± .09, [.13, .27]); TT-TG distance/TDI (3.07 ± 1.55 vs 1.7 ± .7, [.9, 1.84]).

Conclusion: The TT-TG distance, TT-TG distance/TW, and TT-TG distance/TDI measures were 69%, 81%, and 85%, respectively, accurate for determining patellofemoral instability risk. Thresholds for risk were 14.7 mm for TT-TG distance, .36 for TT-TG distance/TW, and 1.88 for TT-TG distance/TDI. The thresholds reported in this study may help in advancing clinical decision-making.

Level of evidence: Level III, diagnostic retrospective comparative observatory trial.

MeSH terms

Adolescent
Adult
Child
Female
Humans
Joint Instability* / diagnostic imaging
Joint Instability* / pathology
Magnetic Resonance Imaging / methods
Male
Patellofemoral Joint* / diagnostic imaging
Patellofemoral Joint* / pathology
Reproducibility of Results
Retrospective Studies
Tibia / diagnostic imaging
Tibia / pathology
Young Adult