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Orthop J Sports MedOrthop J Sports MedOJSspojsOrthopaedic Journal of Sports Medicine2325-9671SAGE Publications Sage CA: Los Angeles, CA 10.1177/2325967118S0014110.1177_2325967118S00141ArticleIs Medial Tibial Slope Associated With Non-contact ACL Tears? An
Analysis Of Primary And Revision Acl Reconstruction Patients Su Alvin Wei-i MD, PhD1Bogunovic Ljiljana MD2Smith Matthew V. MD3Gortz Simon MD4Brophy Robert H. MD5Wright Rick W. MD6Matava Matthew J. MD51 University of Connecticut, Farmington,
CT, USA2 Washington University in St Louis,
Chesterfield, MO, USA3 Washington University in St. Louis,
Chesterfield, MO, USA4 The CORE Institute, Phoenix, AZ,
USA5 Washington University Orthopedics,
Chesterfield, MO, USA6 Washington University, Saint Louis, MO,
USA27 7 2018 7 2018 6 7 suppl4 2018 AOSSM Annual Meeting Abstracts2325967118S00141© The Author(s) 20182018SAGE PublicationsThis open-access article is published and distributed under the
Creative Commons Attribution - NonCommercial - No Derivatives License
(http://creativecommons.org/licenses/by-nc-nd/4.0/), which
permits the noncommercial use, distribution, and reproduction of the article
in any medium, provided the original author and source are credited. You may
not alter, transform, or build upon this article without the permission of
the Author(s). For article reuse guidelines, please visit SAGE’s website at
http://www.sagepub.com/journals-permissions.Objectives:
Increased tibial slope (TS) may be associated with non-contact ACL injuries
although potential confounding effects from various patient characteristics
and radiographic quantification methods have not been rigorously studied.
The association of TS with recurrent non-contact ACL injury after primary
reconstruction is less defined. The purpose of this study was: 1) to assess
the reliability and variability of TS values among different examiners, and
2) to compare TS between patients undergoing primary ACL reconstruction,
re-injured patients undergoing revision ACL reconstruction, and an
ACL-intact cohort.

Methods:
A total of 206 patients were prospectively enrolled in this single center,
IRB-approved study that consisted of 3 groups: 1) ACL intact controls (CTRL,
n=83), 2) first-time ACL injured patients from a non-contact mechanism
(PRIM, n=77), and 3) patients with repeated non-contact ACL injury after
primary ACL reconstruction (REV, n=46). Patients with prior knee surgery,
radiographic signs of arthritis, chondral lesions ≥ grade 2, or insufficient
radiographs were excluded. Repeated measurements of anterior and posterior
TS were performed by 3 fellowship-trained sports medicine surgeons based on
the previously described Utzschneider method that has a strong correlation
to CT and MRI measurements. The anterior tibial slope (ATS) and posterior
tibial slope (PTS) were measured to calculate an approximate mean medial
tibial slope (MTS) based on the anatomic tibial axis. (Fig. 1).
The intra- and inter-observer reliability were assessed by intra-class
correlation coefficients (ICC). The MTS, ATS, PTS, age, BMI and sex
distribution were compared among the three groups using one-way ANOVA with
Tukey’s post hoc test and Chi-square test, respectively. The independent
association of TS with ACL-intact controls (CTRL) vs. positive ACL injury
(PRIM + REV) was assessed by multivariable logistic regression for MTS, ATS,
and PTS, respectively. An a priori power analysis determined that 45
patients per group were needed to achieve a statistical power > 80% to
detect a 1° difference (SD=3°) with α=0.05.

Results:
The ICC for intra- and inter-observer reliability in the calculation of TS
ranged from 0.73-0.89 indicating substantial agreement. There was no
significant difference in values for MTS, ATS, and PTS between the CTRL,
PRIM and REV groups (p=0.42, 0.12, and 0.42, respectively). Patient age was
highest in the CTRL group, followed by the REV, then PRIM groups
(p<0.001) (Table 1). None of the TS values were
independently associated with ACL injury based on multivariable logistic
regression adjusted for age and sex. The mean ATS for all 206 subjects was
5° and 10° greater than that of the MTS and PTS, respectively (p <
0.001). ATS correlated only moderately to PTS (R2=0.49, p <
0.001).

Conclusion:
There is substantial intra- and inter-observer reliability in the
radiographic assessment of medial tibial slope. Medial tibial slope was not
associated with first time non-contact ACL tears or recurrent ACL graft
tears undergoing reconstruction.





Table 1. Patient characteristics and tibial slope quantified for three study
groups.

	CTRL (n=83)	PRIM (n=77	REV (n-46)	p value	
Age (y.o)	37.1 +/-12.3	18.9 +/- 4.6	25.0 +/- 8.2		
Sex (female, %)	56.6%	53.3%	39.1%	0.15	
BMI (kg/m2)	26.6 +/- 5.9	24.7 +/- 4.5	26.5 +/- 4.4	0.83	
ATS (degrees)	14.7 +/- 3.4	13.8 +/- 2.8	13.8 +/- 3.0	0.12	
MTS (degrees)	10.2 +/- 3.1	9.6 +/- 2.7	10.0 +/- 2.7	0.42	
PTS (degrees)	5.6 +/- 3.3	5.4 +/- 3.0	6.1 +/- 2.9	0.12	
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