ACL reconstruction (ACLR) patients commonly adopt poor movement patterns that potentially place them at an increased risk for reinjury if untreated. Limb loading characteristics during functional tasks can highlight movement compensations.


Examine loading symmetry during a bilateral bodyweight squatting task between sexes, compare loading metrics between limbs and sexes, and describe the relationship between loading metrics and patient reported outcomes (PROs) following ACLR.


Cross-Sectional Study



Patients or Other Participants

142 patients (71M/71F, 24.4±11.10yrs) with a primary, unilateral, uncomplicated ACLR completed a squatting assessment and PROs at approximately 5.2 months post-ACLR.

Main Outcome Measure(s)

Normalized limb loading peak force (N/kg) and unilateral cumulative load (%) were collected bilaterally during the squatting task. Limb symmetry index (%) was calculated for normalized peak force. Our first objective compared limb loading symmetry (%) between sexes using independent samples t-test. Our second objective assessed differences in limb loading metrics between limbs and sexes were analyzed via an analysis of covariance. Our third objective was assessed using Spearman Rho correlations to determine the relationship between limb loading metrics and PROs.


The majority of individuals (91/142, 64.1%) offloaded their ACLR limb (ACLR: 6.6±1.56 N/kg; contralateral: 7.3±1.61 N/kg, p<0.001). Females significantly offloaded their ACLR limb (ACLR: 6.3±1.38 N/kg; contralateral: 7.2±1.62 N/kg, p<0.001) where males did not significantly offload their ACLR limb (ACLR 6.98±1.65 N/kg; contralateral: 7.4±1.60, p=0.07). Weak relationships were observed (ρ-value range: -0.23 to 0.19) across limb loading metrics and PROs.


Individuals approximately five months following ACLR, on average, offloaded their ACLR limb compared to the contralateral limb. Patients’ tendency to offload their weight during a squat was influenced by sex. Relationships between limb loading metrics and PROs indicate patients who load their limbs disproportionately have a lower perception in their capability to complete activities of daily living and lower subjective knee function.

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Author notes

Conflict of Interest and Source of Funding: Study was supported by funding from the Innovative, Developmental Exploratory Award (IDEA) research and development fund from the School of Education and Human Development at the University of Virginia. This study was also supported by funding from the graduate student summer research fellowship from the American College of Sports Medicine Biomechanics Interest Group (BIG).

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