Knee biomechanics during a jump-cut maneuver: effects of sex and ACL surgery

Abstract

Purpose: The purpose of this study was to compare kinetic and knee kinematic measurements from male and female anterior cruciate ligament (ACL)-intact (ACLINT) and ACL-reconstructed (ACLREC) subjects during a jump-cut maneuver using biplanar videoradiography.

Methods: Twenty subjects were recruited; 10 ACLINT (5 men and 5 women) and 10 ACLREC (4 men and 6 women, 5 yr postsurgery). Each subject performed a jump-cut maneuver by landing on a single leg and performing a 45° side-step cut. Ground reaction force (GRF) was measured by a force plate and expressed relative to body weight. Six-degree-of-freedom knee kinematics were determined from a biplanar videoradiography system and an optical motion capture system.

Results: ACLINT female subjects landed with a larger peak vertical GRF (P < 0.001) compared with ACLINT male subjects. ACLINT subjects landed with a larger peak vertical GRF (P ≤ 0.036) compared with ACLREC subjects. Regardless of ACL reconstruction status, female subjects underwent less knee flexion angle excursion (P = 0.002) and had an increased average rate of anterior tibial translation (0.05%·ms ± 0.01%·ms, P = 0.037) after contact compared with male subjects. Furthermore, ACLREC subjects had a lower rate of anterior tibial translation compared with ACLINT subjects (0.05%·ms ± 0.01%·ms, P = 0.035). Finally, no striking differences were observed in other knee motion parameters.

Conclusion: Women permit a smaller amount of knee flexion angle excursion during a jump-cut maneuver, resulting in a larger peak vertical GRF and increased rate of anterior tibial translation. Notably, ACLREC subjects also perform the jump cut maneuver with lower GRF than ACLINT subjects 5 yr postsurgery. This study proposes a causal sequence whereby increased landing stiffness (larger peak vertical GRF combined with less knee flexion angle excursion) leads to an increased rate of anterior tibial translation while performing a jump-cut maneuver.

Conflict of interest statement

CONFLICT OF INTEREST

None.

Figures

Figure 1

A, illustration depicting the experimental set-up used to capture both biplanar videoradiography and OMC data during a jump-cut maneuver. A screen directly in front of the subject prompted them with the directional arrow. The subject would land and cut in the direction they were prompted using the opposite leg. For example, if prompted with the left arrow, the subject would land and cut to the left using their right leg. The four OMC cameras are not displayed in this figure; however, they were positioned to capture the retro-reflective markers shown on the subject’s right leg. B, example frame from the Autoscoper markerless tracking software. Each view represents one frame from each of the two videoradiographs generated from the two image intensifiers (Figure 1A). The blue and black portions of the images represent the actual radiographs. The orange femur represents the DRR. Both the DRR and videoradiographs have been enhanced with a sobel edge detection filter and a contact filter. This was done to create a strong visual match between the DRR and actual radiograph. The translational manipulator is shown. This manipulator allowed the user to translate the DRR within the 3-D environment. A rotational manipulator was also available to the user. The DRR is shown here after performing markerless registration. The knee shown in this image is from one of the ACLREC subjects. Both interference screws are visible in the femur and tibia.

Figure 2

A, ACLINT vertical GRF. B, ACLREC vertical GRF. Each subject’s GRF was normalized by their respective weight. Thus, vertical GRF units are in body weights. Notice the highlighted peak in the ACLINT vertical GRF graph. All curves are displayed as mean ± 1 SD. The vertical line on each graph represents the time at contact. C, ACLINT AN/PO translational excursion. D, ACLREC AN/PO translational excursion. Anterior is positive and posterior is negative. All AN/PO translations were normalized for each subject by their respective tibial plateau width. Thus, translational units are defined as a percent of the total tibial width in the anterior-posterior direction. It should be noted that the AN/PO translational excursion data were obtained from the biplanar videoradiography system.

Figure 3

A, ACLINT AD/AB rotational excursion. B, ACLREC AD/AB rotational excursion. Adduction is positive and abduction is negative. C, ACLINT IN/EX rotational excursion. D, ACLREC IN/EX rotational excursion. All rotational excursion units are in degrees. All curves are displayed as mean ± 1 SD. The vertical line on each graph represents the time at contact. It should be noted that these data were obtained from the biplanar videoradiography system.

Figure 4

Left y-axis, minimum knee flexion angle for ACLINT and ACLREC male and female subjects. Minimum flexion occurred at or immediately following ground contact. No statistically significant differences between gender and condition were observed for minimum knee flexion angle values; however, the * represents a p-value of 0.054 denoting an apparent gender difference. Right y-axis, knee flexion angle excursion for ACLINT and ACLREC male and female subjects. Knee flexion angle excursion was defined as the change in knee flexion angle from minimum flexion to maximum flexion. A statistically significant difference was observed between male and female subjects. This is highlighted by the **, which represents a p-value of 0.002. The minimum knee flexion angle and knee flexion angle excursion units are in degrees. It should be noted that these data were obtained from the OMC system.