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. 2017 Jul/Aug;9(4):356-363.
doi: 10.1177/1941738117707758. Epub 2017 May 26.

Relationships Between Knee Extension Moments During Weighted and Unweighted Gait and Strength Measures That Predict Knee Moments After ACL Reconstruction

Erin Hartigan  1 , Jennifer Aucoin  2 , Rita Carlson  3 , Melanie Klieber-Kusak  4 , Thomas Murray  5 , Bernadette Shaw  5 , Michael Lawrence  1
Affiliations

Relationships Between Knee Extension Moments During Weighted and Unweighted Gait and Strength Measures That Predict Knee Moments After ACL Reconstruction

Erin Hartigan et al. Sports Health. 2017 Jul/Aug.

Abstract

Background: Weighted gait increases internal knee extension moment impulses (KEMI) in the anterior cruciate ligament-reconstructed (ACLR) limb; however, limb differences persist.

Hypotheses: (1) KEMI during normal gait will influence KEMI during weighted gait and (2) peak knee extension (PKE) torque and time to reach PKE torque will predict KEMI during gait tasks.

Study design: Descriptive laboratory study.

Methods: Twenty-four women and 14 men completed 3 gait tasks (unweighted, vest, sled) and strength testing after discharge from rehabilitation and clearance to return to sports. KEMI were calculated during the first 25% of stance. PKE torque and time to reach PKE torque were obtained using a dynamometer. Data on the ACLR limb and symmetry indices (SIs) were analyzed for each sex.

Results: Women presented with asymmetrical PKE torques and KEMI across tasks. There were three correlations noted for KEMI: between the walk and vest, walk and sled, and vest and sled tasks. Slower time to PKE torque predicted limb asymmetries across tasks and KEMI in the ACLR limb during the sled task. Men presented with asymmetrical PKE torques and KEMI during the sled task. There was a correlation noted for KEMI between walk and vest tasks only. During the sled task, ACLR limb time to PKE torque predicted KEMI in the ACLR limb and PKE torque SI predicted KEMI SI.

Conclusion: Women use asymmetrical KEMI profiles during all gait tasks, and those with worse KEMI during walking have worse KEMI during weighted gait. Men have asymmetrical KEMI when sled towing, and these KEMIs do not correlate with KEMI during walking or vest tasks.

Clinical relevance: PKE torque deficits persist when attempting to return to sports. Only men use gains in PKE torque to improve KEMI profiles. Although quicker PKE torque generation will increase KEMI in women, normalization of KEMI profiles will not occur by increasing rate of force development only. Gait retraining is recommended to correct asymmetrical KEMI profiles used across gait tasks in women.

Keywords: gait; internal knee extension moment; quadriceps strength; return to sport.

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Conflict of interest statement

The authors report no potential conflicts of interest in the development and publication of this article. This work was supported by University of New England’s PPOR Grant, which paid subject honorariums and disposables for motion analysis, and software fees for motion analysis equipment.

Figures

Figure 1.
Figure 1.
Weighted gait tasks utilized in this study: sled (EliteFTS) and vest (V-Max). BWT, body weight.
See this image and copyright information in PMC

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