The influence of femoral structure, hip capsular constraints, and gluteal muscle strength and activation on temporal patterns of functional valgus collapse

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Jennifer A. Hogg (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Advisor
Sandra Shultz

Abstract: Functional valgus collapse (a combination of knee abduction and internal rotation and hip adduction and internal rotation) is a modifiable lower extremity movement pattern commonly associated with anterior cruciate ligament (ACL) injuries in females. Though the gluteus maximus and gluteus medius have frequently been named contributors to functional valgus collapse, evidence supporting their role in lower extremity movement has been inconsistent, and could in part be due to methodological differences between studies and the accepted practice of analyzing discrete variables instead of overall movement patterns. Better elucidation of gluteal muscle influence on lower extremity biomechanics may be a critical step for the reduction of ACL injury rates, as neuromuscular dysfunction is likely more responsive to injury prevention efforts than are other risk factors such as bony anatomy, ligament quality, or hormonal influences, that are more difficult to modify. Therefore, the purpose of this study was to 1) describe the neuromechanical profiles throughout the landing phase of single-leg and double-leg forward landings in males and females, 2) quantify the contributions of gluteal muscle strength and activation to peak angles and moments of functional valgus collapse after controlling for one’s femoral alignment, and 3) explore the association between gluteal muscle function and overall functional valgus collapse throughout the landing phase. To accomplish this, 45 females and 45 males with no history of knee surgery were measured for femoral anteversion, hip ROM, and hip strength and then underwent biomechanical testing during single-leg and double-leg forward landings to examine muscle activation and 3-dimensional biomechanics. Data were analyzed using conventional group and correlative analyses and also with statistical parametric mapping (SPM), which allowed for a more comprehensive examination of the entire biomechanical time series. Biomechanical variables of interest included joint angles and moments comprising functional valgus collapse: hip adduction and internal rotation and knee abduction and internal rotation. In the comparison between single-leg and double-leg landings by sex, sex differences in the frontal plane were task dependent, though females maintained greater absolute knee abduction and hip adduction throughout the landing phases. Sex by task interactions revealed that females landed with smaller knee adduction angles than males, particularly during the single-leg landing (p=.03), while females’ knee abduction excursion was greater than males’, particularly during the double-leg landing (p=.01). Across task, females displayed 4.1° greater peak knee abduction than males (p=.002), and this was specific to 37-46% of the landing phase (p=.05). Females went through 1.0° more hip abduction than males (p=.05), and used a smaller proportion of their gluteus maximus (p=.01) in both tasks. Examination of gluteal muscle contribution to individual and overall levels of functional valgus collapse in females revealed that at the 18% and 20% time points during the landing phase, less hip abduction strength and greater gluteus medius activation predicted greater peak hip adduction angles (R2 change = .10; p = .02) and higher external hip adduction moments (R2 change = .14, p = .06). Greater hip extension strength predicted greater peak hip abduction angles (R2 change = .08; p = .05), while greater gluteus maximus activation strengthened the prediction of greater initial (R2 change = .10, p = .03) and peak (R2 change = .14, p = .01) knee internal rotation angles. From 7% - 8% of the landing phase, greater external rotation ROM was associated with greater external hip adduction moment (R2 change = .18, p = .01). In males, less hip abduction strength strengthened the prediction of greater initial (R2 change = .12, p = .01) and peak knee internal rotation angles (R2 change = .14, p = .01), lesser peak knee external rotation angles (R2 change = .07, p =.09), and lesser peak knee abduction moments (R2 change = .06, p =.11). Less hip extension strength with greater gluteus maximus activation predicted greater peak hip external rotation moments (R2 change = .14, p = .01). Specifically from the 3% - 9% time points of the landing phase, greater hip extension strength was associated with greater knee abduction moment (R2 change = .17, p = .01) and less hip adduction moment (R2 change = .24, p = .001). At 0% and from 2% - 3% of the landing phase, greater internal and external rotation ROM were associated with greater knee abduction angle (R2 change = .27, p = .01) and greater hip adduction angle (R2 change = .23, p = .02). These results indicate that lower extremity biomechanics during a single-leg landing task are appreciably different than those observed during a double-leg landing task, and that a single-leg landing task elicits more profound sex differences, particularly during the early stage of single-leg load acceptance when ACL injuries are thought to occur (30-40ms post initial ground contact). As such, a single-leg landing task may be more appropriate for biomechanical screening of ACL injury risk. Gluteal strength and activation explained a unique proportion of variance in lower extremity biomechanics beyond what was explained by femoral alignment. In females, weaker gluteal muscles predicted riskier frontal plane hip kinematics. In males, gluteal function was more associated with kinetics. This implies that our male cohort used their musculature to create torque about a joint, whereas our female cohort was unable to create torque. Though femoral alignment (total ROM) explained considerably greater proportions of biomechanical variance than did gluteal function, observed associations between gluteal muscle function and biomechanics occurred 10-20ms after associations between femoral alignment and biomechanics. While the gluteal muscles may act mechanically independent of femoral alignment, it is possible that gluteal muscle function could be temporally linked to one’s femoral alignment. With these findings in mind, it may be beneficial for clinicians to implement gluteal strengthening programs and to encourage gluteal muscle pre-activation in individuals with excessive hip ROM to lessen their propensity for functional valgus collapse.

Additional Information

Publication
Dissertation
Language: English
Date: 2018
Keywords
Anterior cruciate ligament, Gluteal muscles, Statistical parametric mapping, Task differences, Valgus
Subjects
Anterior cruciate ligament $x Wounds and injuries $x Prevention
Jumping $x Physiological aspects
Leg $x Mechanical properties
Leg $x Sex differences
Buttocks $x Muscles
Buttocks $x Muscles

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