The contribution of the tibial tubercle to patellar instability: analysis of tibial tubercle–trochlear groove (TT-TG) and tibial tubercle–posterior cruciate ligament (TT-PCL) distances

Mark J. Heidenreich, Christopher L. Camp, Diane L. Dahm, Michael J. Stuart, Bruce A Levy, Aaron Krych

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Abstract

Purpose: The purpose of this study is to assess the reliability of measuring the tibial tubercle to posterior cruciate (TT-PCL) distance compared to the tibial tubercle to trochlear groove (TT-TG) distance on magnetic resonance imaging (MRI), establish baseline TT-PCL values in patellar instability patients, and determine the predictive value of an excessive TT-PCL distance (≥24 mm) for recurrent patellar instability compared to a TT-TG distance ≥20 mm. Methods: TT-TG and TT-PCL distances were calculated on MRI in a randomized and blinded fashion by two reviewers on 54 patients (59 knees) with patellar instability. Interobserver reliability was assessed using interclass correlation coefficients (ICC). TT-PCL distances were also assessed to establish mean values in patellar instability patients. The ability of excessive TT-PCL and TT-TG distances to predict recurrent instability was assessed by comparing odds ratios, sensitivities, and specificities. Results: Interobserver reliability was excellent for both TT-TG (ICC = 0.978) and TT-PCL (ICC = 0.932). The mean TT-PCL in these 59 knees was 21.7 mm (standard deviation 4.1 mm). Twelve (20 %) of 59 knees had a single dislocation, and 47 (80 %) exhibited 2 or more dislocations. The odds ratios, sensitivities, and specificities of a TT-TG distance ≥20 mm for identifying patients with recurrent dislocation were 5.38, 0.213, and 1.0, respectively, while those of a TT-PCL distance ≥24 mm were 1.46, 0.298, and 0.583, respectively. Of the 10 knees with a TT-TG distance ≥20 mm, all 10 (100 %) had recurrent instability, while 14 (73.7 %) of the 19 knees with a TT-PCL ≥24 mm experienced multiple dislocations (n.s.). Conclusion: Both TT-PCL and TT-TG can be measured on MRI with excellent interobserver reliability. In this series, the mean TT-PCL value in patients with patellar instability was 21.8 mm, but the range was broad. A TT-PCL distance ≥24 mm was found to be less predictive of recurrent instability in this series. For patients experiencing multiple episodes of patellar instability in the setting of a normal TT-TG distance, obtaining the TT-PCL measurement may provide a more focused assessment of the tibial contribution to tubercle lateralization. Level of evidence: III.

Original languageEnglish (US)
JournalKnee Surgery, Sports Traumatology, Arthroscopy
DOIs
StateAccepted/In press - Jul 26 2015

Fingerprint

Ligaments
Knee
Magnetic Resonance Imaging
Odds Ratio
Sensitivity and Specificity
Reproducibility of Results

Keywords

  • Patellar instability
  • Tibial tubercle to posterior cruciate ligament distance
  • Tibial tubercle to trochlear groove distance

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Surgery

Cite this

@article{64526ef4a1e1418390ed08a2acb54df9,
title = "The contribution of the tibial tubercle to patellar instability: analysis of tibial tubercle–trochlear groove (TT-TG) and tibial tubercle–posterior cruciate ligament (TT-PCL) distances",
abstract = "Purpose: The purpose of this study is to assess the reliability of measuring the tibial tubercle to posterior cruciate (TT-PCL) distance compared to the tibial tubercle to trochlear groove (TT-TG) distance on magnetic resonance imaging (MRI), establish baseline TT-PCL values in patellar instability patients, and determine the predictive value of an excessive TT-PCL distance (≥24 mm) for recurrent patellar instability compared to a TT-TG distance ≥20 mm. Methods: TT-TG and TT-PCL distances were calculated on MRI in a randomized and blinded fashion by two reviewers on 54 patients (59 knees) with patellar instability. Interobserver reliability was assessed using interclass correlation coefficients (ICC). TT-PCL distances were also assessed to establish mean values in patellar instability patients. The ability of excessive TT-PCL and TT-TG distances to predict recurrent instability was assessed by comparing odds ratios, sensitivities, and specificities. Results: Interobserver reliability was excellent for both TT-TG (ICC = 0.978) and TT-PCL (ICC = 0.932). The mean TT-PCL in these 59 knees was 21.7 mm (standard deviation 4.1 mm). Twelve (20 {\%}) of 59 knees had a single dislocation, and 47 (80 {\%}) exhibited 2 or more dislocations. The odds ratios, sensitivities, and specificities of a TT-TG distance ≥20 mm for identifying patients with recurrent dislocation were 5.38, 0.213, and 1.0, respectively, while those of a TT-PCL distance ≥24 mm were 1.46, 0.298, and 0.583, respectively. Of the 10 knees with a TT-TG distance ≥20 mm, all 10 (100 {\%}) had recurrent instability, while 14 (73.7 {\%}) of the 19 knees with a TT-PCL ≥24 mm experienced multiple dislocations (n.s.). Conclusion: Both TT-PCL and TT-TG can be measured on MRI with excellent interobserver reliability. In this series, the mean TT-PCL value in patients with patellar instability was 21.8 mm, but the range was broad. A TT-PCL distance ≥24 mm was found to be less predictive of recurrent instability in this series. For patients experiencing multiple episodes of patellar instability in the setting of a normal TT-TG distance, obtaining the TT-PCL measurement may provide a more focused assessment of the tibial contribution to tubercle lateralization. Level of evidence: III.",
keywords = "Patellar instability, Tibial tubercle to posterior cruciate ligament distance, Tibial tubercle to trochlear groove distance",
author = "Heidenreich, {Mark J.} and Camp, {Christopher L.} and Dahm, {Diane L.} and Stuart, {Michael J.} and Levy, {Bruce A} and Aaron Krych",
year = "2015",
month = "7",
day = "26",
doi = "10.1007/s00167-015-3715-4",
language = "English (US)",
journal = "Knee Surgery, Sports Traumatology, Arthroscopy",
issn = "0942-2056",
publisher = "Springer Verlag",

}

TY - JOUR

T1 - The contribution of the tibial tubercle to patellar instability

T2 - analysis of tibial tubercle–trochlear groove (TT-TG) and tibial tubercle–posterior cruciate ligament (TT-PCL) distances

AU - Heidenreich, Mark J.

AU - Camp, Christopher L.

AU - Dahm, Diane L.

AU - Stuart, Michael J.

AU - Levy, Bruce A

AU - Krych, Aaron

PY - 2015/7/26

Y1 - 2015/7/26

N2 - Purpose: The purpose of this study is to assess the reliability of measuring the tibial tubercle to posterior cruciate (TT-PCL) distance compared to the tibial tubercle to trochlear groove (TT-TG) distance on magnetic resonance imaging (MRI), establish baseline TT-PCL values in patellar instability patients, and determine the predictive value of an excessive TT-PCL distance (≥24 mm) for recurrent patellar instability compared to a TT-TG distance ≥20 mm. Methods: TT-TG and TT-PCL distances were calculated on MRI in a randomized and blinded fashion by two reviewers on 54 patients (59 knees) with patellar instability. Interobserver reliability was assessed using interclass correlation coefficients (ICC). TT-PCL distances were also assessed to establish mean values in patellar instability patients. The ability of excessive TT-PCL and TT-TG distances to predict recurrent instability was assessed by comparing odds ratios, sensitivities, and specificities. Results: Interobserver reliability was excellent for both TT-TG (ICC = 0.978) and TT-PCL (ICC = 0.932). The mean TT-PCL in these 59 knees was 21.7 mm (standard deviation 4.1 mm). Twelve (20 %) of 59 knees had a single dislocation, and 47 (80 %) exhibited 2 or more dislocations. The odds ratios, sensitivities, and specificities of a TT-TG distance ≥20 mm for identifying patients with recurrent dislocation were 5.38, 0.213, and 1.0, respectively, while those of a TT-PCL distance ≥24 mm were 1.46, 0.298, and 0.583, respectively. Of the 10 knees with a TT-TG distance ≥20 mm, all 10 (100 %) had recurrent instability, while 14 (73.7 %) of the 19 knees with a TT-PCL ≥24 mm experienced multiple dislocations (n.s.). Conclusion: Both TT-PCL and TT-TG can be measured on MRI with excellent interobserver reliability. In this series, the mean TT-PCL value in patients with patellar instability was 21.8 mm, but the range was broad. A TT-PCL distance ≥24 mm was found to be less predictive of recurrent instability in this series. For patients experiencing multiple episodes of patellar instability in the setting of a normal TT-TG distance, obtaining the TT-PCL measurement may provide a more focused assessment of the tibial contribution to tubercle lateralization. Level of evidence: III.

AB - Purpose: The purpose of this study is to assess the reliability of measuring the tibial tubercle to posterior cruciate (TT-PCL) distance compared to the tibial tubercle to trochlear groove (TT-TG) distance on magnetic resonance imaging (MRI), establish baseline TT-PCL values in patellar instability patients, and determine the predictive value of an excessive TT-PCL distance (≥24 mm) for recurrent patellar instability compared to a TT-TG distance ≥20 mm. Methods: TT-TG and TT-PCL distances were calculated on MRI in a randomized and blinded fashion by two reviewers on 54 patients (59 knees) with patellar instability. Interobserver reliability was assessed using interclass correlation coefficients (ICC). TT-PCL distances were also assessed to establish mean values in patellar instability patients. The ability of excessive TT-PCL and TT-TG distances to predict recurrent instability was assessed by comparing odds ratios, sensitivities, and specificities. Results: Interobserver reliability was excellent for both TT-TG (ICC = 0.978) and TT-PCL (ICC = 0.932). The mean TT-PCL in these 59 knees was 21.7 mm (standard deviation 4.1 mm). Twelve (20 %) of 59 knees had a single dislocation, and 47 (80 %) exhibited 2 or more dislocations. The odds ratios, sensitivities, and specificities of a TT-TG distance ≥20 mm for identifying patients with recurrent dislocation were 5.38, 0.213, and 1.0, respectively, while those of a TT-PCL distance ≥24 mm were 1.46, 0.298, and 0.583, respectively. Of the 10 knees with a TT-TG distance ≥20 mm, all 10 (100 %) had recurrent instability, while 14 (73.7 %) of the 19 knees with a TT-PCL ≥24 mm experienced multiple dislocations (n.s.). Conclusion: Both TT-PCL and TT-TG can be measured on MRI with excellent interobserver reliability. In this series, the mean TT-PCL value in patients with patellar instability was 21.8 mm, but the range was broad. A TT-PCL distance ≥24 mm was found to be less predictive of recurrent instability in this series. For patients experiencing multiple episodes of patellar instability in the setting of a normal TT-TG distance, obtaining the TT-PCL measurement may provide a more focused assessment of the tibial contribution to tubercle lateralization. Level of evidence: III.

KW - Patellar instability

KW - Tibial tubercle to posterior cruciate ligament distance

KW - Tibial tubercle to trochlear groove distance

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U2 - 10.1007/s00167-015-3715-4

DO - 10.1007/s00167-015-3715-4

M3 - Article

C2 - 26210961

AN - SCOPUS:84937844992

JO - Knee Surgery, Sports Traumatology, Arthroscopy

JF - Knee Surgery, Sports Traumatology, Arthroscopy

SN - 0942-2056

ER -