A predictive model to estimate knee-abduction moment: implications for development of a clinically applicable patellofemoral pain screening tool in female athletes.
BACKGROUND
Prospective measures of high external knee-abduction moment (KAM) during landing identify female athletes at increased risk of patellofemoral pain (PFP). A clinically applicable screening protocol is needed.


OBJECTIVE
To identify biomechanical laboratory measures that would accurately quantify KAM loads during landing that predict increased risk of PFP in female athletes and clinical correlates to laboratory-based measures of increased KAM status for use in a clinical PFP injury-risk prediction algorithm. We hypothesized that we could identify clinical correlates that combine to accurately determine increased KAM associated with an increased risk of developing PFP.


METHODS
Descriptive laboratory study.


METHODS
Biomechanical laboratory.


METHODS
Adolescent female basketball and soccer players (n = 698) from a single-county public school district.


METHODS
We conducted tests of anthropometrics, maturation, laxity, flexibility, strength, and landing biomechanics before each competitive season. Pearson correlation and linear and logistic regression modeling were used to examine high KAM (>15.4 Nm) compared with normal KAM as a surrogate for PFP injury risk.


RESULTS
The multivariable logistic regression model that used the variables peak knee-abduction angle, center-of-mass height, and hip rotational moment excursion predicted KAM associated with PFP risk (>15.4 NM of KAM) with 92% sensitivity and 74% specificity and a C statistic of 0.93. The multivariate linear regression model that included the same predictors accounted for 70% of the variance in KAM. We identified clinical correlates to laboratory measures that combined to predict high KAM with 92% sensitivity and 47% specificity. The clinical prediction algorithm, including knee-valgus motion (odds ratio [OR] = 1.46, 95% confidence interval [CI] = 1.31, 1.63), center-of-mass height (OR = 1.21, 95% CI = 1.15, 1.26), and hamstrings strength/body fat percentage (OR = 1.80, 95% CI = 1.02, 3.16) predicted high KAM with a C statistic of 0.80.


CONCLUSIONS
Clinical correlates to laboratory-measured biomechanics associated with an increased risk of PFP yielded a highly sensitive model to predict increased KAM status. This screening algorithm consisting of a standard camcorder, physician scale for mass, and handheld dynamometer may be used to identify athletes at increased risk of PFP.
Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children's Hospital Medical Center, OH.
Gregory D
GD
Myer
Kevin R
KR
Ford
Kim D Barber
KD
Foss
Mitchell J
MJ
Rauh
Mark V
MV
Paterno
Timothy E
TE
Hewett
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D018771:Arthralgia / Q000175:diagnosis* / Q000503:physiopathology*; D001490:Basketball / Q000293:injuries / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D006615:Hip / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D016015:Logistic Models; D008403:Mass Screening / Q000295:instrumentation / Q000379:methods; D008954:Models, Biological; D015233:Models, Statistical; D009068:Movement / Q000502:physiology; D010147:Pain Measurement / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012399:Rotation; D012680:Sensitivity and Specificity; D012916:Soccer / Q000293:injuries / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
assessment tools; high-risk biomechanics; knee injury prevention; patellofemoral risk factors; targeted neuromuscular training