Quadriceps muscle volume positively contributes to ACL volume

Abstract

Females have smaller anterior cruciate ligaments (ACLs) than males and smaller ACLs have been associated with a greater risk of ACL injury. Overall body dimensions do not adequately explain these sex differences. This study examined the extent to which quadriceps muscle volume (VOLQUAD) positively predicts ACL volume (VOLACL) once sex and other body dimensions were accounted for. Physically active males (N = 10) and females (N = 10) were measured for height, weight, and body mass index (BMI). Three‐Tesla magnetic resonance images of their dominant and nondominant thigh and knee were then obtained to measure VOLACL, quadriceps, and hamstring muscle volumes, femoral notch width, and femoral notch width index. Separate three‐step regressions estimated associations between VOLQUAD and VOLACL (third step), after controlling for sex (first step) and one body dimension (second step). When controlling for sex and sex plus BMI, VOLHAM, notch width, or notch width index, VOLQUAD consistently exhibited a positive association with VOLACL in the dominant leg, nondominant leg, and leg‐averaged models (p < 0.05). Findings were inconsistent when controlling for sex and height (p = 0.038–0.102). Once VOLQUAD was included, only notch width and notch width index retained a statistically significant individual association with VOLACL (p < 0.01). Statement of Clinical Significance: The positive association between VOLQUAD and VOLACL suggests ACL size may in part be modifiable. Future studies are needed to determine the extent to which an appropriate training stimulus (focused on optimizing overall lower extremity muscle mass development) can positively impact ACL size and structure in young females.

Anterior cruciate ligament injury: towards a gendered environmental approach

“…The principles of tissue adaptability state that soft tissue and bone will adapt and model according to the forces with which they are subjected, and is the cornerstone of preventative and rehabilitative exercise programming. 78 There is some evidence to suggest that the structure of the ACL can change with loading 79 80 , and a recent study found a significant relationship between quadriceps muscle volume and ACL volume; 81 however, the consequences and implications are unknown. Anatomical risk factors for ACL injury may very well include both a biological and a societal influence (ie, the 'entanglement' of sex/gender).…”

Sex-Specific Changes in Physical Risk Factors for Anterior Cruciate Ligament Injury by Chronological Age and Stages of Growth and Maturation From 8 to 18 Years of Age

“…We included ALM given the functional importance of the leg musculature in movement control and reported associations between thigh muscle mass and ACL size. 31,32 After in-depth review, 39 articles were excluded for not meeting the eligibility criteria, and 2 papers were excluded for supplying duplicate data. The most common reasons for exclusion were not providing stratified data by sex and age or Tanner stage, the wrong study design or outcome, only reporting 1 sex or age span, or insufficient data to confirm that the age span represented 2 or more pubertal stages.…”

“…31,149,150 Some data indicated that the sex difference in ACL size could be partly explained by sex differences in muscle size. 31,32 When comparing the sex-specific trajectories in thigh muscle mass with those of ACL size (see Supplemental File 1, Figures 19 and D1), girls accumulated thigh muscle mass and increased ACL size at lower rates (with earlier plateaus) than boys, with sex differences becoming increasingly apparent by approximately 14 years of age (data not available by maturity level). Although we cannot change bone geometry, these findings are potentially promising in that ACL size (and, in turn, anterior knee laxity) could be modifiable to some extent if addressed early.…”

ACL Research Retreat IX Summary Statement: The Pediatric Athlete, March 17–19, 2022; High Point, North Carolina

“…Additionally, sex-specific trajectories in ACL size (emerging at 14 years) closely followed sex-specific trajectories in thigh-muscle-mass development (emerging at 13 years), which led to discussions of ACL size and the extent to which these trajectories could be altered (ie, restraint capacity increased) during the developmental process. Research has indicated that ACL size is more strongly associated with muscle size than with other body dimensions 25,26 and was also associated with prolonged training, 27,28 particularly when training began at younger ages. 27 Despite widespread evidence of bone and tendon adaptations to increases in load, how ligamentous tissue responds to increases in training load or if the training load alone is sufficient to increase this capacity is not widely understood.…”