Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Educational and Psychological Studies (Education)

Date of Defense


First Committee Member

Joseph Signorile

Second Committee Member

Thomas Best

Third Committee Member

Moataz Eltoukhy

Fourth Committee Member

Michael Baraga


Quadriceps tendon autografts (QT) are increasingly popular as a primary graft choice for anterior cruciate ligament reconstruction (ACLR); yet no study has compared QT and bone-patellar tendon-bone autograft (BTB) superficial quadriceps neuromuscular activity levels during gait and isometric strength testing. The objective of this study was to determine if harvesting the central portion of the QT will alter gait biomechanics and RF firing patterns during gait and an isometric maximum voluntary contraction (MVC). Thirty-four subjects (18-40 y), who underwent ACLR using BTB (n=17) or QT (n=17) at a single institution, and seventeen healthy age-matched controls (C) participated. Subjects had no neuromuscular pathology or prior surgery on either lower extremity, were at least one-year post-ACLR, and were cleared for full activity by their treating surgeons. Post-operative rehabilitation protocols were the same for all subjects. Synchronized electromyography (EMG) and isometric torque data were collected on ACLR subjects in seated position with hips flexed to 90° and knee at 60o flexion. Subjects were asked to extend their knees as quickly as possible and perform an MVC for 3s. A practice trial and three test trials were completed with 30s rest intervals. Synchronized EMG was also collected in conjunction with sagittal kinetic/kinematic data as subjects walked at their self-selected cadence along a 20-foot course containing two offset force plates. Three gait trials were performed with one complete gait cycle identified for analysis during each trial. Mixed 2 condition x 2 limb (affected versus unaffected) ANOVAs were used to examine differences in average and peak torque values during isometric testing, joint angles, joint moments and ground reaction forces (GRF) during gait testing. RF, VM, and VL EMG amplitudes were assessed during gait and RF/VL and RF/VM EMG ratios during both isometric and gait testing. Lysholm and IKDC scores were compared between groups using paired t-tests. Significantly lower values were seen for the affected compared to the unaffected extremity for peak (p=.008; η2=.201) and average torque (p<.0001; η2=.321) with no significant differences between groups. Additionally, no significant differences in RF/VL or RF/VM ratios were seen between affected and unaffected limbs or groups during gait or MVC. In the QT group, maximum knee angle was significantly less than that of the BTB group in the unaffected extremity (MD=-15.00, p=.002). In summary, at greater than one year following ACLR, QT and BTB autographs showed similar isometric strength deficits; however, no differences in quadriceps muscles EMG ratios were seen between the groups during isometric testing or gait, although kinematic asymmetries were observed in the QT group. Additional research is warranted to further investigate the longitudinal effect of kinetic and kinematic alterations on knee function and joint health after QT ACLR. Our results provide additional evidence for the QT as a choice for ACLR, as this graft harvest does not adversely affect quadriceps firing patterns.


ACL Reconstruction; Arthroscopy; Knee; Quadriceps; EMG; Isometric