Asymmetric ground reaction forces and knee kinematics during squat after anterior cruciate ligament (ACL) reconstruction.
BACKGROUND
This bilateral squat study tests whether people with anterior cruciate ligament (ACL) reconstruction have symmetric three-dimensional ground reaction forces (GRFs) and symmetric anterior-posterior (AP) translation rates of the femur with respect to the tibia when compared with healthy control subjects. We hypothesized that there would be no long-term asymmetry in knee kinematics and kinetics in ACL reconstructed subjects following surgery and rehabilitation.


METHODS
Position and GRF data were collected on eight ACL reconstructed and eight control subjects during bilateral squat. The rate of relative AP translation was determined for each subject. Principal component models were developed for each of the three GRF waveforms. Principal component scores were used to assess symmetry within the ACL reconstructed group and within the control group.


RESULTS
ACL reconstructed knees analyzed in early flexion during squat descent displayed a four-fold greater rate of change in anterior translation in the reconstructed knee relative to the contralateral side than did a similar comparison of normal knees. Differences were found between the ACL reconstructed subjects' injured and uninjured limbs for all GRFs.


CONCLUSIONS
Subjects following ACL reconstruction had asymmetric GRFs and relative rates of AP translation at an average of seven years after ACL reconstructive surgery when compared with control subjects.


CONCLUSIONS
These alterations in loading may lead to altered load distributions across the knee joint and may put some subjects at risk for future complications such as osteoarthritis.
Campbell Clinic Department of Orthopaedics and Biomedical Engineering, University of Tennessee Health Science Center, Memphis, TN 38163, USA. Electronic address: bsanford@uthsc.edu.
Brooke A
BA
Sanford
Department of Biomedical Engineering, University of Memphis, Memphis, TN 38152, USA. Electronic address: john.williams@memphis.edu.
John L
JL
Williams
Physical Therapy Department, University of Tennessee Health Science Center, Memphis, TN 38163, USA. Electronic address: azuckerl@uthsc.edu.
Audrey
A
Zucker-Levin
Campbell Clinic Department of Orthopaedics and Biomedical Engineering, University of Tennessee Health Science Center, Memphis, TN 38163, USA. Electronic address: wmihalko@campbellclinic.com.
William M
WM
Mihalko
D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D009040:Motion Pictures; D011187:Posture; D025341:Principal Component Analysis; D059869:Radiostereometric Analysis; D016059:Range of Motion, Articular; D013977:Tibia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055815:Young Adult
Anterior cruciate ligament; Ground reaction force; Kinematics; Squat