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Landing Mechanics Between Noninjured Women and Women With Anterior Cruciate Ligament Reconstruction During 2 Jump Tasks

Alexis Ortiz, PT, PhD, SCS, CSCS^,,*, Sharon Olson, PT, PhD, Charles L. Libby, PT, MEd, ATC, EMT, Elaine Trudelle-Jackson, PT, PhD^||, Young-Hoo Kwon, PhD^¶, Bruce Etnyre, PT, PhD^# and William Bartlett, PT, PhD

From the Physical Therapy Program, School of Health Professions, University of Puerto Rico–Medical Sciences Campus, San Juan, Puerto Rico, Department of Physical Education & Recreation, University of Puerto Rico–Rio Piedras Campus, San Juan, Puerto Rico, School of Physical Therapy, Texas Woman’s University, Houston, Texas, ^|| School of Physical Therapy, Texas Woman’s University, Dallas, Texas, ^¶ Department of Kinesiology, Texas Woman’s University, Denton, Texas, and ^# Department of Kinesiology, Rice University, Houston, Texas

^* Address correspondence to Alexis Ortiz, PT, PhD, SCS, CSCS, PO Box 365067, San Juan, PR, US 00936-5067 (e-mail: alexisortiz{at}cprs.rcm.upr.edu).

Background: Women with anterior cruciate ligament reconstruction have different neuromuscular strategies than noninjured women during functional tasks after ligament reconstruction and rehabilitation.

Hypothesis: Landing from a jump creates high loads on the knee creating dynamic instability in women with anterior cruciate ligament reconstruction, whereas noninjured women have stable knee landing mechanics.

Study Design: Controlled laboratory study.

Methods: Fifteen noninjured women and 13 women with anterior cruciate ligament reconstruction performed 5 trials of a single-legged 40-cm drop jump and 2 trials of a 20-cm up-down hop task. Multivariate analyses of variance were used to compare hip and knee joint kinematics, knee joint moments, ground-reaction forces, and electromyographic findings between the dominant leg in noninjured women and reconstructed leg in women with anterior cruciate ligament reconstruction.

Results: No statistically significant differences between groups were found for peak hip and knee joint angles for the drop jump task. Statistically significant differences in neuromuscular activity (P = .001) and anterior-posterior knee shear forces (P < .001) were seen in women with anterior cruciate ligament reconstruction compared with noninjured women in the drop jump task. However, no statistically significant differences (P > .05) between groups were found for either peak hip and knee joint angles, peak joint kinetics, or electromyographic findings during the up-down hop task.

Conclusion: Women with anterior cruciate ligament reconstruction have neuromuscular strategies that allow them to land from a jump similar to healthy women, but they exhibit joint moments that could predispose them to future injury if they participate in sports that require jumping and landing.

Key Words: anterior cruciate ligament (ACL) • landing • knee • biomechanics