A Modifiable ACL Risk Factor · 2018-06-05 · Background Results References: (1) Hudek, R.,...
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Background Results References: (1) Hudek, R., Schmutz, S., Regenfelder, F., Fuchs, B., Koch, P. 2009. Novel measurement technique of the tibial slope on conventional MRI. Clin Orthop Relat Res 467(8):2066-2072. (2) Sturnick, D., Vacek, P., DeSarno, M., Gardner-Morse, Mack., Tourville, T., Slauterbeck, J., Johnson, R., Shultz, S., Beynnon, B. 2015 Combined anatomic factors predicting risk of anterior cruciate ligament injury for males and females. Am J Sports Med 43:839. A Modifiable ACL Risk Factor Katherine Bojicic, Mélanie Beaulieu, Daniel Imaizumi Krieger, James Ashton-Miller and Edward M. Wojtys Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI USA Aims Methods 118 MRI radiographs (76 tear, 42 control) obtained from University of Michigan MedSport were measured. 58 female and 60 male, between 16-40 years of age Tear MRIs were obtained from subjects who had sustained a non- contact injury All MRI images were de-identified and the individual taking measurements was blinded to tear vs. non-tear images through a randomization process Measures: Posterior Tibial Slope (PTS), Middle Cartilage Slope (MCS), Meniscal Cartilage Height (MCH), Meniscal Bone Angle (MBA*) * All measurements were taken in the lateral compartment as previous studies showed lateral as opposed to medial measurements had a greater predictive power of ACL injury]. Conclusions Acknowledgements: Michigan SBRP, C. Robbins, S. Riutta, E. Sibilsky Enselman a b Figure 2: Measurements of knee geometries. a) A line (L1) was drawn to connect the superior-anterior and superior-posterior cortices of the tibial plateau. b) A second line (L2) along the superior surface of the wedge shaped posterior meniscal cartilage was drawn. c) A third line (L3) joining the most superior portions of the anterior and posterior located prominences of the middle articular cartilage surface was drawn. d) A fourth line (L4) was drawn that ran from the top of the posterior meniscal cartilage to the point at which the posterior meniscus intersected the middle articular cartilage. L4 was drawn so that it was parallel to the tibial access while still connecting the two aforementioned points. c The aim of this study was to quantify the relationship between BMI and several knee geometries as potential risk factors for ACL injury. Methods cont… Figure 1: Finding the longitudinal tibial axis using the Hudek et. al method (1,2) A sagittal plane image containing (1) the intercondylar eminence, (2) posterior cruciate ligament attachment, and (3) concave anterior and posterior tibial cortices was chosen for measurements. The tibial longitudinal axis was found by drawing two overlapping circles on the proximal tibia. A line connecting the middle of each circle defined the tibial axis. Table 1. Participant demographic, BMI, and knee morphological data as well as univariate analysis of age, BMI, PTS, MCS, PMH, MBA. Tear Mean Std. Deviation p value Odds Ratio 95% C.I. Age yes 24.6 7.1 0.122 0.962 0.916- 1.010 no 26.5 8.3 BMI Yes 26.4 4.1 0.429 0.973 0.908- 1.042 No 26.2 5.3 PTS Yes 6.7 3.9 0.043 1.118 1.003- 1.247 No 5.4 3.4 MCS Yes 4.4 3.7 0.037 1.125 1.007- 1.254 No 2.9 3.3 MBA Yes 28.6 4.1 0.246 0.949 0.868- 1.037 no 29.6 4.6 PMH yes 6.3 0.9 0.072 0.692 0.463- 1.033 no 6.5 1.0 Table 2. Multivariate analysis of PTS and MCS with BMI centered around the mean (cBMI). Only the interaction variable PTS*cBMI was significant (odds ratio 1.2). Model 1 p value Odds Ratio PTS 0.061 1.12 cBMI 0.140 0.875 PTS*cBMI .050 1.029 Model 2 p value Odds Ratio MCS 0.037 1.13 cBMI 0.707 0.977 MCS*cBMI 0.395 1.185 Table 3. Percent increase in odds of suffering an ACL tear with increases in PTS (degrees) and/or BMI (kg/m2) according to our regression model. PTS BMI +1° +2° +3° +0 kg/m 2 12% 25% 40% +1 kg/m 2 15% 29% 45% +2 kg/m 2 19% 33% 49% +3 kg/m 2 22% 37% 54% +4 kg/m 2 26% 41% 58% +5 kg/m 2 30% 45% 63% • The effect of an increase in lateral posterior tibial slope on ACL tear probability is affected by BMI. An increase in BMI will increase the risk of ACL tear when an increase in lateral posterior tibial slope is present. • An increase in lateral posterior tibial slope or lateral middle cartilage slope increases the risk of an ACL tear. • A multivariate logistic regression model that included PTS, BMI centered around the mean (cBMI) and their interaction (PTC*cBMI) was found to significantly predict ACL injury risk (p = 0.040). • For every 1° increase in PTS, there is an 11% increase in the odds of tearing the ACL, keeping cBMI constant. • Interpretation of the interaction term is that for a 1 unit increase in BMI from the average in combination with a 1° increase in PTS, there is a 15% increase in the odds of ACL injury (Table 3). • A multivariate regression model that included MCS, cBMI, and their interaction (MCS*cBMI) was not shown to significantly predict ACL injury risk (p = 0.132). ACL injury rates remain high perhaps due to the lack of understanding of the injury risk factors and their interaction. Several non-modifiable anatomical ACL risk factors have been identified including increases in posterior tibial slope (PTS) or middle cartilage slope (MCS). Similarly, a decrease in the lateral meniscal height in the posterior compartment (PMH) may increase the risk of ACL injury in females while a decrease in meniscal bone angle (MBA) may increase ACL injury risk in males. A high body mass index (BMI) may be a modifiable ACL injury risk factor. The relationship between non-modifiable and modifiable risk factors has not been explored. We hypothesized that an increased BMI in the presence of an increased posterior tibial slope or middle cartilage slope would increase the risk of ACL injury. We also hypothesized that an increased BMI in the presence of a decreased posterior meniscal height or meniscal bone angle would result in an increased risk of ACL injury. Hypotheses
Transcript of A Modifiable ACL Risk Factor · 2018-06-05 · Background Results References: (1) Hudek, R.,...
Background
Results
References: (1) Hudek, R., Schmutz, S., Regenfelder, F., Fuchs, B., Koch, P. 2009. Novel measurement technique of the tibial slope on conventional MRI. Clin Orthop Relat Res 467(8):2066-2072. (2) Sturnick, D., Vacek, P., DeSarno, M., Gardner-Morse, Mack., Tourville, T., Slauterbeck, J., Johnson, R., Shultz, S., Beynnon, B. 2015 Combined anatomic factors predicting risk of anterior cruciate ligament injury for males and females. Am J Sports Med 43:839.
A Modifiable ACL Risk Factor Katherine Bojicic, Mélanie Beaulieu, Daniel Imaizumi Krieger, James Ashton-Miller and Edward M. Wojtys
Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI USA
Aims
Methods § 118 MRI radiographs (76 tear, 42 control) obtained from University of
Michigan MedSport were measured. § 58 female and 60 male, between 16-40 years of age § Tear MRIs were obtained from subjects who had sustained a non-
contact injury § All MRI images were de-identified and the individual taking
measurements was blinded to tear vs. non-tear images through a randomization process
§ Measures: Posterior Tibial Slope (PTS), Middle Cartilage Slope (MCS), Meniscal Cartilage Height (MCH), Meniscal Bone Angle (MBA*)
* All measurements were taken in the lateral compartment as previous studies showed lateral as opposed to medial measurements had a greater predictive power of ACL injury].
Conclusions
Acknowledgements: Michigan SBRP, C. Robbins, S. Riutta, E. Sibilsky Enselman
a
b
Figure 2: Measurements of knee geometries. a) A line (L1) was drawn to connect the superior-anterior and superior-posterior cortices of the tibial plateau. b) A second line (L2) along the superior surface of the wedge shaped posterior meniscal cartilage was drawn. c) A third line (L3) joining the most superior portions of the anterior and posterior located prominences of the middle articular cartilage surface was drawn. d) A fourth line (L4) was drawn that ran from the top of the posterior meniscal cartilage to the point at which the posterior meniscus intersected the middle articular cartilage. L4 was drawn so that it was parallel to the tibial access while still connecting the two aforementioned points.
c
The aim of this study was to quantify the relationship between BMI and several knee geometries as potential risk factors for ACL injury.
Methods cont…
Figure 1: Finding the longitudinal tibial axis using the Hudek et. al method (1,2) A sagittal plane image containing (1) the intercondylar eminence, (2) posterior cruciate ligament attachment, and (3) concave anterior and posterior tibial cortices was chosen for measurements. The tibial longitudinal axis was found by drawing two overlapping circles on the proximal tibia. A line connecting the middle of each circle defined the tibial axis.
Table&1.&Participant&demographic,&BMI,&and&knee&morphological&data&as&well&as&univariate&analysis&of&age,&BMI,&PTS,&MCS,&PMH,&MBA.&
! Tear& Mean& Std.&Deviation& p&value& Odds&
Ratio& 95%&C.I.&
Age& yes! 24.6! 7.1!0.122! 0.962! 0.916-
1.010!& no! 26.5! 8.3!
BMI& Yes! 26.4! 4.1!0.429! 0.973! 0.908-
1.042!& No! 26.2! 5.3!
PTS& Yes! 6.7! 3.9!0.043! 1.118! 1.003-
1.247!& No! 5.4! 3.4!
MCS& Yes! 4.4! 3.7!0.037! 1.125! 1.007-
1.254!& No! 2.9! 3.3!
MBA& Yes! 28.6! 4.1!0.246! 0.949! 0.868-
1.037!& no! 29.6! 4.6!
PMH& yes! 6.3! 0.9!0.072! 0.692! 0.463-
1.033!! no! 6.5! 1.0!!
Table&2.&Multivariate&analysis&of&PTS&and&MCS&with&BMI¢ered&around&the&mean&(cBMI).&Only&the&interaction&variable&PTS*cBMI&was&significant&(odds&ratio&1.2).&
Model&1&
! p&value& Odds&Ratio&PTS& 0.061! 1.12!cBMI& 0.140! 0.875!PTS*cBMI& .050! 1.029!
Model&2&
! p&value& Odds&Ratio&
MCS& 0.037! 1.13!cBMI& 0.707! 0.977!MCS*cBMI& 0.395! 1.185!!
Table&3.&Percent&increase&in&odds&of&suffering&an&ACL&tear&with&increases&in&PTS&(degrees)&and/or&BMI&(kg/m2)&according&to&
our®ression&model.&&&&
! PTS&
BMI&
! +1°! +2°! +3°!+0!kg/m2! 12%! 25%! 40%!+1!kg/m2! 15%! 29%! 45%!+2!kg/m2! 19%! 33%! 49%!+3!kg/m2! 22%! 37%! 54%!+4!kg/m2! 26%! 41%! 58%!+5!kg/m2! 30%! 45%! 63%!
!
• The effect of an increase in lateral posterior tibial slope on ACL tear probability is affected by BMI. An increase in BMI will increase the risk of ACL tear when an increase in lateral posterior tibial slope is present.
• An increase in lateral posterior tibial slope or lateral middle cartilage slope increases the risk of an ACL tear.
• A multivariate logistic regression model that included PTS, BMI centered around the mean (cBMI) and their interaction (PTC*cBMI) was found to significantly predict ACL injury risk (p = 0.040).
• For every 1° increase in PTS, there is an 11% increase in the odds of tearing the ACL, keeping cBMI constant.
• Interpretation of the interaction term is that for a 1 unit increase in BMI
from the average in combination with a 1° increase in PTS, there is a 15% increase in the odds of ACL injury (Table 3).
• A multivariate regression model that included MCS, cBMI, and their interaction (MCS*cBMI) was not shown to significantly predict ACL injury risk (p = 0.132).
§ ACL injury rates remain high perhaps due to the lack of understanding of the injury risk factors and their interaction. Several non-modifiable anatomical ACL risk factors have been identified including increases in posterior tibial slope (PTS) or middle cartilage slope (MCS). Similarly, a decrease in the lateral meniscal height in the posterior compartment (PMH) may increase the risk of ACL injury in females while a decrease in meniscal bone angle (MBA) may increase ACL injury risk in males. A high body mass index (BMI) may be a modifiable ACL injury risk factor. The relationship between non-modifiable and modifiable risk factors has not been explored.
We hypothesized that an increased BMI in the presence of an increased posterior tibial slope or middle cartilage slope would increase the risk of ACL injury. We also hypothesized that an increased BMI in the presence of a decreased posterior meniscal height or meniscal bone angle would result in an increased risk of ACL injury.
Hypotheses
