Knee joint mechanics during gait after anterior cruciate ligament reconstruction using a partial or full thickness quadriceps tendon autograft at 2 years after surgery.

Background: Despite quadriceps weakness in individuals after quadriceps tendon anterior cruciate ligament reconstruction (QT-ACLR), and its association with knee joint mechanics, no studies have addressed gait mechanics in both partial-thickness (PT-Q) and full-thickness (FT-Q) options for QT-ACLR.

Objective: To assess gait mechanics across a QT-ACLR cohort. We hypothesized that QT-ACLR would show changes in knee joint mechanics compared to control participants (CON) and nonoperated limbs. Additionally, we hypothesized that FT-Q operated limbs would show greater changes compared to PT-Q and CON.

Design: Retrospective cohort study.

Setting: University-affiliated sports medicine institute.

Participants: Sixteen patients who underwent QT-ACLR (7 FT-Q: Age (years) = 28.6 ± 7.3, post-op (months) = 23.5 ± 10.7, 9 PT-Q: Age = 25.2 ± 4.3, post-op = 24.4 ± 11.7) were recruited and compared to 11 CON (age = 23.4 ± 4.8).

Intervention: Participants underwent gait testing with force plate integrated motion capture.

Main Outcome Measures: Mixed repeated-measures analyses of covariance, adjusted for gait speed, were used to determine significant main effects or interactions in peak knee flexion angle, sagittal knee range of motion, peak internal knee extension moment (KEM), and peak internal knee flexion moment.

Results: When measured an average of 2 years after surgery, no main effect for limb or limb by depth interaction were detected. A significant effect by group was observed for peak KEM (p = .03, η = .27) and peak knee flexion angle (p = .04, η = .24) in the loading response phase. FT-Q (p = .02) and PT-Q (p = .03) showed lower KEM compared to the CON group in both limbs. The FT-Q group showed lower peak knee flexion angle compared to the CON group (p = .01).

Conclusions: Knee joint symmetry may be recovered 2 years following QT-ACLR, but lower KEM compared to CON for both graft options and lower peak knee flexion angle than CON for the FT-Q group may indicate a need for further investigation in QT-ACLR.