A simple evaluation of anterior cruciate ligament femoral tunnel position

The inclination angle and femoral tunnel angle

Kenneth David Illingworth, Daniel Hensler, Zachary Working, Jeffrey Alexander Macalena, Scott Tashman, Freddie H. Fu

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Background: Postoperative determination of tunnel position after anterior cruciate ligament (ACL) reconstruction can be challenging.Hypothesis: The femoral tunnel angle and inclination angle are reliable methods for evaluating tunnel position after ACL reconstruction while aiding in determining whether an ACL reconstruction falls outside an anatomic range as defined on 3-dimensional (3D) computed tomography (CT).Study Design: Cohort study (diagnosis); Level of evidence, 3.Methods: Fifty patients were included who received single-bundle ACL reconstructions with postoperative flexion weightbearing radiographs, magnetic resonance imaging (MRI), and CT scans. Femoral tunnel angles were determined from posterior-to-anterior postoperative radiographs, and inclination angles were determined from sagittal MRI. The ACL reconstructions were grouped by surgical technique, transtibial (TT) or tibial tunnel independent (TTI), and as either falling inside or outside an anatomic range on 3D CT.Results: Patients with tunnel positions within an anatomic range, as previously defined, had a larger femoral tunnel angle (39.3° ± 4.2°) and smaller inclination angle (49.5° ± 2.7°) than patients who fell outside an anatomic range (17.2° ± 12.5° and 62.3° ± 7.8°, respectively) (P <.001). Patients in the TTI group had a larger femoral tunnel angle (37.6° ± 9.30°) and smaller inclination angle (51.8° ± 6.5°) than those in the TT group (14.2° ± 9.3° and 63.5° ± 7.2°, respectively) (P <.001). Posterior-to-anterior femoral tunnel position was negatively correlated with femoral tunnel angle (P <.001, r =.78) and positively correlated with inclination angle (P <.001, r =.74). Based on a receiver operating characteristic (ROC) curve, a femoral tunnel angle of 32.7° (100% sensitivity and 85% specificity) and inclination angle of 55° (100% sensitivity and 87.5% specificity) were determined to distinguish ACL reconstructions that fell either within or outside an anatomic range on 3D CT.Conclusion: Femoral tunnel angle and inclination angle can be reliably determined from both posterior-to-anterior radiographs and sagittal MRI and provide a useful metric for characterizing femoral tunnel position.

Original languageEnglish (US)
Pages (from-to)2611-2618
Number of pages8
JournalAmerican Journal of Sports Medicine
Volume39
Issue number12
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

Fingerprint

Anterior Cruciate Ligament
Thigh
Anterior Cruciate Ligament Reconstruction
Tomography
Magnetic Resonance Imaging
Accidental Falls
Sensitivity and Specificity
Weight-Bearing
ROC Curve
Cohort Studies

Keywords

  • 3D CT
  • ACL MRI
  • anatomic ACL
  • femoral tunnel angle
  • inclination angle
  • tibial tunnel-independent drilling
  • transtibial drilling

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Medicine(all)

Cite this

A simple evaluation of anterior cruciate ligament femoral tunnel position : The inclination angle and femoral tunnel angle. / Illingworth, Kenneth David; Hensler, Daniel; Working, Zachary; Macalena, Jeffrey Alexander; Tashman, Scott; Fu, Freddie H.

In: American Journal of Sports Medicine, Vol. 39, No. 12, 01.12.2011, p. 2611-2618.

Research output: Contribution to journalArticle

Illingworth, Kenneth David ; Hensler, Daniel ; Working, Zachary ; Macalena, Jeffrey Alexander ; Tashman, Scott ; Fu, Freddie H. / A simple evaluation of anterior cruciate ligament femoral tunnel position : The inclination angle and femoral tunnel angle. In: American Journal of Sports Medicine. 2011 ; Vol. 39, No. 12. pp. 2611-2618.
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abstract = "Background: Postoperative determination of tunnel position after anterior cruciate ligament (ACL) reconstruction can be challenging.Hypothesis: The femoral tunnel angle and inclination angle are reliable methods for evaluating tunnel position after ACL reconstruction while aiding in determining whether an ACL reconstruction falls outside an anatomic range as defined on 3-dimensional (3D) computed tomography (CT).Study Design: Cohort study (diagnosis); Level of evidence, 3.Methods: Fifty patients were included who received single-bundle ACL reconstructions with postoperative flexion weightbearing radiographs, magnetic resonance imaging (MRI), and CT scans. Femoral tunnel angles were determined from posterior-to-anterior postoperative radiographs, and inclination angles were determined from sagittal MRI. The ACL reconstructions were grouped by surgical technique, transtibial (TT) or tibial tunnel independent (TTI), and as either falling inside or outside an anatomic range on 3D CT.Results: Patients with tunnel positions within an anatomic range, as previously defined, had a larger femoral tunnel angle (39.3° ± 4.2°) and smaller inclination angle (49.5° ± 2.7°) than patients who fell outside an anatomic range (17.2° ± 12.5° and 62.3° ± 7.8°, respectively) (P <.001). Patients in the TTI group had a larger femoral tunnel angle (37.6° ± 9.30°) and smaller inclination angle (51.8° ± 6.5°) than those in the TT group (14.2° ± 9.3° and 63.5° ± 7.2°, respectively) (P <.001). Posterior-to-anterior femoral tunnel position was negatively correlated with femoral tunnel angle (P <.001, r =.78) and positively correlated with inclination angle (P <.001, r =.74). Based on a receiver operating characteristic (ROC) curve, a femoral tunnel angle of 32.7° (100{\%} sensitivity and 85{\%} specificity) and inclination angle of 55° (100{\%} sensitivity and 87.5{\%} specificity) were determined to distinguish ACL reconstructions that fell either within or outside an anatomic range on 3D CT.Conclusion: Femoral tunnel angle and inclination angle can be reliably determined from both posterior-to-anterior radiographs and sagittal MRI and provide a useful metric for characterizing femoral tunnel position.",
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AU - Hensler, Daniel

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AU - Tashman, Scott

AU - Fu, Freddie H.

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N2 - Background: Postoperative determination of tunnel position after anterior cruciate ligament (ACL) reconstruction can be challenging.Hypothesis: The femoral tunnel angle and inclination angle are reliable methods for evaluating tunnel position after ACL reconstruction while aiding in determining whether an ACL reconstruction falls outside an anatomic range as defined on 3-dimensional (3D) computed tomography (CT).Study Design: Cohort study (diagnosis); Level of evidence, 3.Methods: Fifty patients were included who received single-bundle ACL reconstructions with postoperative flexion weightbearing radiographs, magnetic resonance imaging (MRI), and CT scans. Femoral tunnel angles were determined from posterior-to-anterior postoperative radiographs, and inclination angles were determined from sagittal MRI. The ACL reconstructions were grouped by surgical technique, transtibial (TT) or tibial tunnel independent (TTI), and as either falling inside or outside an anatomic range on 3D CT.Results: Patients with tunnel positions within an anatomic range, as previously defined, had a larger femoral tunnel angle (39.3° ± 4.2°) and smaller inclination angle (49.5° ± 2.7°) than patients who fell outside an anatomic range (17.2° ± 12.5° and 62.3° ± 7.8°, respectively) (P <.001). Patients in the TTI group had a larger femoral tunnel angle (37.6° ± 9.30°) and smaller inclination angle (51.8° ± 6.5°) than those in the TT group (14.2° ± 9.3° and 63.5° ± 7.2°, respectively) (P <.001). Posterior-to-anterior femoral tunnel position was negatively correlated with femoral tunnel angle (P <.001, r =.78) and positively correlated with inclination angle (P <.001, r =.74). Based on a receiver operating characteristic (ROC) curve, a femoral tunnel angle of 32.7° (100% sensitivity and 85% specificity) and inclination angle of 55° (100% sensitivity and 87.5% specificity) were determined to distinguish ACL reconstructions that fell either within or outside an anatomic range on 3D CT.Conclusion: Femoral tunnel angle and inclination angle can be reliably determined from both posterior-to-anterior radiographs and sagittal MRI and provide a useful metric for characterizing femoral tunnel position.

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KW - 3D CT

KW - ACL MRI

KW - anatomic ACL

KW - femoral tunnel angle

KW - inclination angle

KW - tibial tunnel-independent drilling

KW - transtibial drilling

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