Neuromuscular Intervention Targeted to Mechanisms of ACL Load in Female Athletes
| Status: | Completed |
|---|---|
| Conditions: | Hospital, Orthopedic |
| Therapuetic Areas: | Orthopedics / Podiatry, Other |
| Healthy: | No |
| Age Range: | 10 - 19 |
| Updated: | 10/14/2017 |
| Start Date: | June 2009 |
| End Date: | June 2013 |
Neuromuscular Intervention Targeted to Mechanisms of ACL Load in Female
Females who participate in cutting and landing sports suffer anterior cruciate ligament (ACL)
injuries at a 2 to 10-fold greater rate than males participating in the same high-risk
sports. Fifty to 100 percent of ACL injured females will suffer osteoarthritis of the injured
knee within one to two decades of the injury. External knee abduction moment (LOAD) predicts
ACL injury with high sensitivity and specificity in female athletes. Control of lateral trunk
motion (LTM) also predicts ACL injury with similar levels of sensitivity and specificity in
female athletes. These predictors may be linked, as lateral positioning of the trunk can
create high knee abduction load via both biomechanical and neuromuscular mechanisms. The
mechanism of ACL injury in females include high knee LOAD and high LTM, with the majority of
body weight shifted over the injured limb and the foot positioned lateral to the body's
center of mass. An unanticipated perturbation is also often a contributor to the injury
mechanism. LTM may result in increased knee LOAD by increasing the lateral position and
magnitude of the GRF vector (ΔGRFv) or by increasing reactive hip adductor torque (HAdT). Our
long-term objectives are to determine the mechanisms that cause ACL injury in female athletes
and to develop neuromuscular training (NMT) interventions that specifically target these
mechanisms. If the objectives of this proposal are achieved, an evidence-based NMT
intervention will be developed and made available nationally that will effectively and
efficiently reduce ACL injury risk in high-risk female athletes. The major goal of this
proposal is to determine if increased LTM increases coronal plane knee load in high-risk
groups of female athletes. This application will test the central hypotheses that LTM
increases knee LOAD and that NMT that is targeted toward increasing coronal plane control of
trunk motion will decrease knee LOAD in females with moderate and high knee LOAD. Aim 1 is
designed to determine the mechanisms by which trunk motion may increase knee LOAD in female
athletes. Coronal plane control of the trunk (LTM) will be examined relative to ΔGRFv, HAdT
and knee LOAD. We will determine if increased LTM increases knee LOAD by biomechanical
(increased ΔGRFv) and/or neuromuscular (increased relative HAdT) mechanisms that may underlie
increased LOAD in female athletes. The central hypothesis of Aim 1 is that increased LTM will
increase knee LOAD in female athletes by increasing ΔGRFv, by increasing HAdT or via a
combination of these mechanisms during cutting and landing. We hypothesize that females with
neither mechanism will have low knee LOAD, those with increased ΔGRFv or HAdT will have
moderate LOAD and those with increased ΔGRFv and HAdT will have high knee LOAD. Aim 2 is
designed to determine if NMT that decreases coronal plane trunk motion will decrease knee
LOAD in knee load group clusters in a randomized controlled trial. The central hypothesis of
Aim 2 is that NMT will decrease knee LOAD in the moderate LOAD group by decreasing ΔGRFv or
HAdT and will decrease LOAD to the greatest extent in the high LOAD group by decreasing both
ΔGRFv and HAdT.
injuries at a 2 to 10-fold greater rate than males participating in the same high-risk
sports. Fifty to 100 percent of ACL injured females will suffer osteoarthritis of the injured
knee within one to two decades of the injury. External knee abduction moment (LOAD) predicts
ACL injury with high sensitivity and specificity in female athletes. Control of lateral trunk
motion (LTM) also predicts ACL injury with similar levels of sensitivity and specificity in
female athletes. These predictors may be linked, as lateral positioning of the trunk can
create high knee abduction load via both biomechanical and neuromuscular mechanisms. The
mechanism of ACL injury in females include high knee LOAD and high LTM, with the majority of
body weight shifted over the injured limb and the foot positioned lateral to the body's
center of mass. An unanticipated perturbation is also often a contributor to the injury
mechanism. LTM may result in increased knee LOAD by increasing the lateral position and
magnitude of the GRF vector (ΔGRFv) or by increasing reactive hip adductor torque (HAdT). Our
long-term objectives are to determine the mechanisms that cause ACL injury in female athletes
and to develop neuromuscular training (NMT) interventions that specifically target these
mechanisms. If the objectives of this proposal are achieved, an evidence-based NMT
intervention will be developed and made available nationally that will effectively and
efficiently reduce ACL injury risk in high-risk female athletes. The major goal of this
proposal is to determine if increased LTM increases coronal plane knee load in high-risk
groups of female athletes. This application will test the central hypotheses that LTM
increases knee LOAD and that NMT that is targeted toward increasing coronal plane control of
trunk motion will decrease knee LOAD in females with moderate and high knee LOAD. Aim 1 is
designed to determine the mechanisms by which trunk motion may increase knee LOAD in female
athletes. Coronal plane control of the trunk (LTM) will be examined relative to ΔGRFv, HAdT
and knee LOAD. We will determine if increased LTM increases knee LOAD by biomechanical
(increased ΔGRFv) and/or neuromuscular (increased relative HAdT) mechanisms that may underlie
increased LOAD in female athletes. The central hypothesis of Aim 1 is that increased LTM will
increase knee LOAD in female athletes by increasing ΔGRFv, by increasing HAdT or via a
combination of these mechanisms during cutting and landing. We hypothesize that females with
neither mechanism will have low knee LOAD, those with increased ΔGRFv or HAdT will have
moderate LOAD and those with increased ΔGRFv and HAdT will have high knee LOAD. Aim 2 is
designed to determine if NMT that decreases coronal plane trunk motion will decrease knee
LOAD in knee load group clusters in a randomized controlled trial. The central hypothesis of
Aim 2 is that NMT will decrease knee LOAD in the moderate LOAD group by decreasing ΔGRFv or
HAdT and will decrease LOAD to the greatest extent in the high LOAD group by decreasing both
ΔGRFv and HAdT.
1. Specific Aim 1 Determine the mechanisms by which trunk motion increases knee load in
females.
Rationale Aim 1 Knee external abduction moment (LOAD) and lateral trunk motion (LTM) are
known to be strong predictors of ACL injury risk in female athletes, but it is not known
whether these predictors are linked and which athletes are at increased risk. In
addition, we do not know the specific neuromuscular mechanisms that predispose these
athletes to greater risk of injury. Neuromuscular control of the trunk will be examined
relative to GRF position and magnitude, hip torque and knee LOAD. We will determine if
increased ΔGRFv and increased relative hip adductor torque (HAdT) underlie increased
knee LOAD in females.
Central Hypothesis Aim 1 Lateral trunk motion will increase knee LOAD in female athletes
by increased ΔGRFv, increased HAdT or by a combination of these two mechanisms during
cutting and landing.
Hypothesis 1.1. Increased LTM induced by unanticipated lateral cutting will increase
knee LOAD by increasing ΔGRFv, adjusting for HAdT, in female athletes.
Hypothesis 1.2. Increased LTM induced by single-leg medial drop landing will increase
knee LOAD by increasing HAdT, adjusting for ΔGRFv, in female athletes.
Hypothesis 1.3. Increased LTM induced by combined drop landing and unanticipated lateral
cutting will result in combinatorial increases in knee LOAD by increasing ΔGRFv and HAdT
in female athletes.
Hypothesis 1.4 Females with low ΔGRFv, low HAdT, and low knee LOAD will form a distinct
group or cluster of subjects, those with high ΔGRFv or HAdT and moderate LOAD will form
another cluster, and those with high ΔGRFv, high HAdT and high LOAD will form the last
distinct group using data collected during DLUC.
2. Specific Aim 2 Determine if NMT that decreases coronal plane trunk motion will decrease
knee abduction LOAD in a double-blind cluster (by school and team) randomized controlled
trial (RCT).
Rationale Aim 2 This aim will determine how NMT targeted to LTM and its two knee loading
mechanisms, ΔGRFv and HAdT, will affect knee LOAD in low, moderate and high LOAD subgroups of
female athletes.
Central Hypotheses Aim 2 NMT will increase control of coronal plane trunk motion and decrease
knee LOAD by either mechanical (ΔGRFv), neuromuscular (HAdT) or both mechanisms and pre-test
low, moderate and high knee LOAD subgroups of female athletes will demonstrate differential
effects of NMT.
Hypothesis 2.1 Knee LOAD will be lower in trained than untrained females during landing and
cutting.
Hypothesis 2.2 Post-test knee LOAD will not differ in trained high, moderate and low knee
LOAD subgroups. Hypothesis 2.3 Post-test ΔGRFv and HAdT will not differ in trained high,
moderate and low LOAD subgroups.
Hypothesis 2.3 Post-test knee LOAD, ΔGRFv and HAdT values will not differ from pre-test
values in untrained high, moderate and low knee LOAD subgroups.
Program Director/Principal Investigator (Last, First, Middle): Hewett, Timothy, Edwin PHS
398/2590 (Rev. 11/07) Page Continuation Format Page
A. Specific Aims The Specific Aims have not been modified from the original application. Our
long-term goals are to determine the mechanisms by which female athletes become more
susceptible to ACL injury and to develop interventions that address these mechanisms in order
to reduce knee loads and ACL injury risk. The major goal of this proposal is to determine if
decreased neuromuscular control of the trunk increases coronal plane knee load in high-risk
groups of females. This overall objective of this application is to test the central
hypotheses that lateral trunk motion increases knee load and that neuromuscular training that
increases control of trunk motion will decrease knee abduction loading in females with
moderate and high knee loads. Our rationale for this project is that its successful
completion will provide a strong, evidence-based intervention that will effectively decrease
ACL injury risk in high-risk female athletes.
B. Studies and Results
We continue to utilize a prospective randomized controlled design for Specific Aims 1 and 2
as outlined in the original funded application. The Boone County Superintendent and the Boone
County School Board approved the participation (testing, busing, randomized intervention,
etc) of the school systems' girls' athletic programs (Basketball, Soccer and Volleyball) at
their monthly school board meeting on Thursday, June 11, 2009 and pre-testing began on
September 1, 2009. As outlined, school-sponsored basketball, soccer and volleyball teams from
the Boone County, Kentucky school system have been and are almost completely recruited,
tested and tracked. Testing will be completed by December 31, 2010. Female subjects from all
the county high school and junior high schools are being screened prior to the start of their
basketball and soccer and volleyball seasons.
A total of 23 teams yielding 318 basketball players have been pre-screened and trained and
post-screened September 1, 2009 through April 30, 2010. A total of 29 teams of approximately
306 soccer and volleyball players (31 of which were not new athletes and were tested in prior
basketball season) were pre-screened, trained and post-screened between May 2010 and December
2010. We have faced challenges recruiting soccer players at the junior high school level in
the county school system. Some of the junior high schools do not have organized soccer teams.
We are addressing this challenge by recruiting volleyball teams within the county in order to
fill in all of our randomized blocks. In addition, we will capture those athletes that will
go on to play high school soccer, volleyball and basketball within the Fayette county school
system (see supplement summary below). Thus far, we have enrolled and pretested (N=31 tested
for both seasons) and tested a total of 593 athletes for our randomized controlled trial from
9/1/09 through 12/31/10. The breakdown by sport and school level is summarized in the
Enrollment Table. There were 558 athletes made the cuts on their respective teams who were
randomized by cluster (team) into the intervention. This number includes all athletes who
completed at least 1 intervention training session.
For the initial biomechanical analyses, we have chosen to focus on Hypothesis 1.4 with the
use Latent Profile Analysis (LPA). We will use LPA to examine whether we can cluster subjects
with similar characteristics of the GRFv, HAdT, hip moments (minimum and maximum), lateral
trunk motion and center of gravity displacement into distinct neuromuscular profiles. Our
latent profile analyses will evaluate independent variables across the multiple tasks to form
groups of girls with similar neuromuscular patterns for these variables where the
heterogeneity of response pattern is minimized within each profile and maximized across
profiles. Initially, two profiles are specified for the LPA model, then, in a stepwise
fashion, the number of profiles specified is increased by one. At each step, changes in
Bayesian information criteria (BIC), adjusted for sample size, is used to assess model fit
and identify the number of profiles needed. The point at which the number of profiles is
deemed adequate is when no significant drop in BIC is seen when the profile number is
increased. In addition, the Lo-Mendell-Rubin adjusted likelihood ratio test is used to
determine the optimal number of profiles.(Lo 2001) The analysis was implemented using Mplus
5.(Muthen 2007) Validation of profile group includes examination as an independent predictor
of LOAD.
Analysis has begun and profiles have been created for the pre-test movements. Graphs
depicting the standardized means along with the 2 generalized profiles are shown in Figure 1.
For presentation purposes it is necessary to show the standardized values as the variables
are on different scales, with hugely varying mean values. Due to the underlying normality
assumption, it was necessary to transform the lateral trunk motion variable to the loge
scale. In addition, it is necessary to account for the correlation between some of these
variables; in particular maximum hip moment and GRFv and HAdT. We are continuing to examine
the potential LPA models at this time and will be checking them against the post intervention
data to determine any emergent profiles. Comparison of mean KAM, with and without adjustment
for age and pubertal status by profile will also be the focus of future analyses.
Figure 1. Profile analysis of Pre-Test Data Set (N=457) In addition, we have performed this
initial assessment of the efficacy of the Randomized controlled intervention and will be
presenting these initial results (The effect of Trunk focused Neuromuscular training on Hip
Strength) at a national meeting this coming July.
females.
Rationale Aim 1 Knee external abduction moment (LOAD) and lateral trunk motion (LTM) are
known to be strong predictors of ACL injury risk in female athletes, but it is not known
whether these predictors are linked and which athletes are at increased risk. In
addition, we do not know the specific neuromuscular mechanisms that predispose these
athletes to greater risk of injury. Neuromuscular control of the trunk will be examined
relative to GRF position and magnitude, hip torque and knee LOAD. We will determine if
increased ΔGRFv and increased relative hip adductor torque (HAdT) underlie increased
knee LOAD in females.
Central Hypothesis Aim 1 Lateral trunk motion will increase knee LOAD in female athletes
by increased ΔGRFv, increased HAdT or by a combination of these two mechanisms during
cutting and landing.
Hypothesis 1.1. Increased LTM induced by unanticipated lateral cutting will increase
knee LOAD by increasing ΔGRFv, adjusting for HAdT, in female athletes.
Hypothesis 1.2. Increased LTM induced by single-leg medial drop landing will increase
knee LOAD by increasing HAdT, adjusting for ΔGRFv, in female athletes.
Hypothesis 1.3. Increased LTM induced by combined drop landing and unanticipated lateral
cutting will result in combinatorial increases in knee LOAD by increasing ΔGRFv and HAdT
in female athletes.
Hypothesis 1.4 Females with low ΔGRFv, low HAdT, and low knee LOAD will form a distinct
group or cluster of subjects, those with high ΔGRFv or HAdT and moderate LOAD will form
another cluster, and those with high ΔGRFv, high HAdT and high LOAD will form the last
distinct group using data collected during DLUC.
2. Specific Aim 2 Determine if NMT that decreases coronal plane trunk motion will decrease
knee abduction LOAD in a double-blind cluster (by school and team) randomized controlled
trial (RCT).
Rationale Aim 2 This aim will determine how NMT targeted to LTM and its two knee loading
mechanisms, ΔGRFv and HAdT, will affect knee LOAD in low, moderate and high LOAD subgroups of
female athletes.
Central Hypotheses Aim 2 NMT will increase control of coronal plane trunk motion and decrease
knee LOAD by either mechanical (ΔGRFv), neuromuscular (HAdT) or both mechanisms and pre-test
low, moderate and high knee LOAD subgroups of female athletes will demonstrate differential
effects of NMT.
Hypothesis 2.1 Knee LOAD will be lower in trained than untrained females during landing and
cutting.
Hypothesis 2.2 Post-test knee LOAD will not differ in trained high, moderate and low knee
LOAD subgroups. Hypothesis 2.3 Post-test ΔGRFv and HAdT will not differ in trained high,
moderate and low LOAD subgroups.
Hypothesis 2.3 Post-test knee LOAD, ΔGRFv and HAdT values will not differ from pre-test
values in untrained high, moderate and low knee LOAD subgroups.
Program Director/Principal Investigator (Last, First, Middle): Hewett, Timothy, Edwin PHS
398/2590 (Rev. 11/07) Page Continuation Format Page
A. Specific Aims The Specific Aims have not been modified from the original application. Our
long-term goals are to determine the mechanisms by which female athletes become more
susceptible to ACL injury and to develop interventions that address these mechanisms in order
to reduce knee loads and ACL injury risk. The major goal of this proposal is to determine if
decreased neuromuscular control of the trunk increases coronal plane knee load in high-risk
groups of females. This overall objective of this application is to test the central
hypotheses that lateral trunk motion increases knee load and that neuromuscular training that
increases control of trunk motion will decrease knee abduction loading in females with
moderate and high knee loads. Our rationale for this project is that its successful
completion will provide a strong, evidence-based intervention that will effectively decrease
ACL injury risk in high-risk female athletes.
B. Studies and Results
We continue to utilize a prospective randomized controlled design for Specific Aims 1 and 2
as outlined in the original funded application. The Boone County Superintendent and the Boone
County School Board approved the participation (testing, busing, randomized intervention,
etc) of the school systems' girls' athletic programs (Basketball, Soccer and Volleyball) at
their monthly school board meeting on Thursday, June 11, 2009 and pre-testing began on
September 1, 2009. As outlined, school-sponsored basketball, soccer and volleyball teams from
the Boone County, Kentucky school system have been and are almost completely recruited,
tested and tracked. Testing will be completed by December 31, 2010. Female subjects from all
the county high school and junior high schools are being screened prior to the start of their
basketball and soccer and volleyball seasons.
A total of 23 teams yielding 318 basketball players have been pre-screened and trained and
post-screened September 1, 2009 through April 30, 2010. A total of 29 teams of approximately
306 soccer and volleyball players (31 of which were not new athletes and were tested in prior
basketball season) were pre-screened, trained and post-screened between May 2010 and December
2010. We have faced challenges recruiting soccer players at the junior high school level in
the county school system. Some of the junior high schools do not have organized soccer teams.
We are addressing this challenge by recruiting volleyball teams within the county in order to
fill in all of our randomized blocks. In addition, we will capture those athletes that will
go on to play high school soccer, volleyball and basketball within the Fayette county school
system (see supplement summary below). Thus far, we have enrolled and pretested (N=31 tested
for both seasons) and tested a total of 593 athletes for our randomized controlled trial from
9/1/09 through 12/31/10. The breakdown by sport and school level is summarized in the
Enrollment Table. There were 558 athletes made the cuts on their respective teams who were
randomized by cluster (team) into the intervention. This number includes all athletes who
completed at least 1 intervention training session.
For the initial biomechanical analyses, we have chosen to focus on Hypothesis 1.4 with the
use Latent Profile Analysis (LPA). We will use LPA to examine whether we can cluster subjects
with similar characteristics of the GRFv, HAdT, hip moments (minimum and maximum), lateral
trunk motion and center of gravity displacement into distinct neuromuscular profiles. Our
latent profile analyses will evaluate independent variables across the multiple tasks to form
groups of girls with similar neuromuscular patterns for these variables where the
heterogeneity of response pattern is minimized within each profile and maximized across
profiles. Initially, two profiles are specified for the LPA model, then, in a stepwise
fashion, the number of profiles specified is increased by one. At each step, changes in
Bayesian information criteria (BIC), adjusted for sample size, is used to assess model fit
and identify the number of profiles needed. The point at which the number of profiles is
deemed adequate is when no significant drop in BIC is seen when the profile number is
increased. In addition, the Lo-Mendell-Rubin adjusted likelihood ratio test is used to
determine the optimal number of profiles.(Lo 2001) The analysis was implemented using Mplus
5.(Muthen 2007) Validation of profile group includes examination as an independent predictor
of LOAD.
Analysis has begun and profiles have been created for the pre-test movements. Graphs
depicting the standardized means along with the 2 generalized profiles are shown in Figure 1.
For presentation purposes it is necessary to show the standardized values as the variables
are on different scales, with hugely varying mean values. Due to the underlying normality
assumption, it was necessary to transform the lateral trunk motion variable to the loge
scale. In addition, it is necessary to account for the correlation between some of these
variables; in particular maximum hip moment and GRFv and HAdT. We are continuing to examine
the potential LPA models at this time and will be checking them against the post intervention
data to determine any emergent profiles. Comparison of mean KAM, with and without adjustment
for age and pubertal status by profile will also be the focus of future analyses.
Figure 1. Profile analysis of Pre-Test Data Set (N=457) In addition, we have performed this
initial assessment of the efficacy of the Randomized controlled intervention and will be
presenting these initial results (The effect of Trunk focused Neuromuscular training on Hip
Strength) at a national meeting this coming July.
Inclusion Criteria:
- Female
- Soccer, Basketball, or Volleyball athlete
- Attends Middle School or High School in Boone County or Fayette County KY
Exclusion Criteria:
- Male
We found this trial at
1
site
3333 Burnet Avenue # Mlc3008
Cincinnati, Ohio 45229
Cincinnati, Ohio 45229
1-513-636-4200
Cincinnati Children's Hospital Medical Center Patients and families from across the region and around the...
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