1. Knee Joint Kinematic and Kinetic Asymmetries During Single Limb Landings Among Recreational Athletes With and Without a History of ACL Reconstruction
Flannery E, SPT; Kraich L, SPT; Jenkins W, PT, DHS, LATC, ATC; Willson J, PT, PhD
Human Movement Analysis Laboratory, Department of Physical Therapy, East Carolina University, Greenville NC
INTRODUCTION
RESULTS
DISCUSSION
Approximately 200,000 ACL injuries occur each year in the US (7)
1 in 17 patients sustain a second ACL injury within 2 years and 1 in 3.7 sustain a second ACL injury within 10 years of ACL reconstruction (ACLR) (8)
Subjects demonstrate altered single and double limb landing mechanics in the involved limb post-ACL reconstruction
Decreased peak knee flexion (1,10), knee flexion excursion (4), knee adduction (1), vertical ground reaction force (6), knee extension moment (3,4), and sagittal plane knee symmetry (5)
Subjects after ACLR demonstrate higher peak tibiofemoral joint compressive forces during single limb drop-landing tasks when compared to healthy controls (9)
No long term analyses of symmetry in jump landing mechanics between limbs among people with and without a history of ACLR
Significant interactions were found between limb (involved versus uninvolved) and group (ACL versus healthy matched control) for:
Peak knee flexion angle (p = 0.02), knee flexion excursion (p = 0.005), knee extension moment (p = 0.01), peak tibiofemoral joint anterior shear force (p = 0.002), knee proportion of support moment (p = 0.002)
No significant interactions were found between limb and group for:
Knee flexion at initial contact (p = 0.47), peak knee adduction angle (p = 0.095), knee adduction excursion (p = 0.18), peak knee abduction moment (p = 0.20), peak vertical ground reaction force (p = 0.48), peak tibiofemoral joint compression force (p = 0.10), total support moment (p = 0.17)
Subjects after ACLR land with significantly decreased peak knee flexion, knee flexion excursion, peak knee extension moment, peak tibiofemoral anterior shear, and knee proportion of the support moment in the ACLR lower extremity
No side-to-side differences within healthy control group
Asymmetry between limbs was only apparent among ACLR participants
Increased asymmetry in knee extension moments between limbs of people after ACLR increases the odds of a second ACLR(8)
Neuromuscular integration deficits after ACLR may play a role in long term asymmetries at the knee during single limb landing tasks
Cautious movement (quadriceps avoidance pattern)
Increased hip and ankle strategies, demonstrating offloading of the knee during single limb landing
Altered bilateral lower extremity movement patterns may be present after ACL reconstruction
Altered neuromuscular recruitment patterns between limbs may develop, persist, and contribute to risk of reinjury
Psychological components may contribute to single limb landing after ACL reconstruction, leading to straighter, stiffer landing mechanics on the reconstructed limb
Figure 1. Peak knee flexion (degrees) during a single limb landing from a jump.
Figure 2. Knee flexion excursion (degrees) during a single limb landing from a jump.
PURPOSE
Evaluate kinematic, kinetic, and support moment side-to-side symmetry at the knee between recreational athletes with and without a history of ACLR during single limb landing from a jump
METHODS
Participants
28 recreational athletes (18 females/10 males)
Inclusion criteria: 2-7 years post ACL reconstruction, one involved lower extremity, 18 to 40 years old
Exclusion criteria: surgery to contralateral lower extremity, injury to either lower limb limiting exercise in past two years
28 healthy matched controls (gender, body mass, Tegner)
Procedure
Maximum vertical jump determined using
Vertec®
Six jumps from bilateral stance to 75% of
maximum vertical jump height, with single
limb landing
Analysis
31 reflective markers tracked with an 8-camera Qualysis (Gothenburg, Sweden) motion analysis system (240 Hz)
Variables examined: C-motion software (Bethesda, MD)
peak knee flexion
knee flexion excursion
peak knee extension moment
peak vertical GRF
peak TFJ anterior shear and compression (2)
knee proportion of support moment
Variable interactions between lower extremities
and groups determined using two-way ANOVA
during the first 60% of landing with the level of
significance for all tests set at p < 0.05
Effect sizes examined using Cohen’s d
LIMITATIONS
Figure 3. Peak knee extension moment (Nm/kg*m) during a single limb landing from a jump.
Figure 4. Peak tibiofemoral joint anterior shear force (BW) during a single limb landing from a jump.
Subjects matched with respect to three variables only (gender, body mass, Tegner)
Heterogeneity among subjects with ACL reconstruction
Concurrent meniscus injury, graft type
Recall bias/accuracy of information (no medical charts)
Anticipatory activity versus reactionary sport-specific activity
Group
Peak Knee Flexion
Knee Flexion Excursion
Peak Knee Extension Moment
Peak TFJ Anterior Shear Force
Knee Proportion of Support Moment
Between Limbs
ACLR
-.39
-.78
-.58
-.69
-.67
Control
.08
-.07
.16
.12
.29
Negative values indicate smaller values in the involved limb
Between Groups
-.04
.51
-.01
.23
.55
Negative values indicate smaller bilateral values in the ACLR group
CLINICAL RELEVANCE
Addressing neuromuscular control deficits may be equally as important as strengthening in subjects after ACLR
Focusing on “softer” landing strategies emphasizing increased peak knee flexion and knee flexion excursion during single limb landing may help to reduce incidence of reinjury in subjects after ACL reconstruction
Figure 5. Knee proportion of support moment (%) during a single limb landing from a jump.
Table 1. Effect sizes (Cohen’s d). Black = small effect; blue = moderate effect; red = large effect.
REFERENCES
Delahunt E, Sweeney L, et al J Orthop Res 30:
DeVita P, Hortobagyi T J Appl Biomech 17:
Ernst G, Saliba E, et al Phys Ther 80:
Ithurburn MP, Paterno MV, et al Am J Sport Med 43: 2727.
Lepley L, Wojtys E, et al Clin Biomech 30:
Paterno M, Ford K, et al Clin J Sport Med 17:
Paterno M, Rauh M, et al Am J Sport Med 42:
Paterno M, Schmitt L, et al Am J Sport Med 38:
Tsai LC, McLean S, et al J Orthop Res 30:
Xergia S, Pappas E, et al J Orthop Sport Phys 43: