Knee Kinematics During Noncontact Anterior Cruciate Ligament Injury as Determined From Bone Bruise Location.
BACKGROUND
The motions causing noncontact anterior cruciate ligament (ACL) injury remain unclear. Tibiofemoral bone bruises are believed to be the result of joint impact near the time of ACL rupture. The locations and frequencies of these bone bruises have been reported, but there are limited data quantifying knee position and orientation near the time of injury based on these contusions.


OBJECTIVE
Knee position and orientation near the time of noncontact ACL injury include extension and anterior tibial translation.


METHODS
Descriptive laboratory study.


METHODS
Magnetic resonance images of 8 subjects with noncontact ACL injuries were acquired within 1 month of injury and were subsequently analyzed. All subjects exhibited bruises on both the femur and tibia in both medial and lateral compartments. The outer margins of bone and the bone bruise surfaces were outlined on each image to create a 3-dimensional model of each subject's knee in its position during magnetic resonance imaging (MRI position). Numerical optimization was used to maximize overlap of the bone bruises on the femur and tibia and to predict the position of injury. Flexion angle, valgus orientation, internal tibial rotation, and anterior tibial translation were measured in both the MRI position and the predicted position of injury. Differences in kinematics between the MRI position, which served as an unloaded reference, and the predicted position of injury were compared by use of paired t tests.


RESULTS
Flexion angle was near full extension in both the MRI position and the predicted position of injury (8° vs 12°; P = .2). Statistically significant increases in valgus orientation (5°; P = .003), internal tibial rotation (15°; P = .003), and anterior tibial translation (22 mm; P < .001) were observed in the predicted position of injury relative to the MRI position.


CONCLUSIONS
These results suggest that for the bone bruise pattern studied, landing on an extended knee is a high risk for ACL injury. Extension was accompanied by increased anterior tibial translation (22 mm), internal tibial rotation (15°), and valgus rotation (5°) in the predicted position of injury relative to the MRI position.


CONCLUSIONS
This study provides novel data characterizing the motions associated with ACL injury, information critical to improving strategies aimed at injury prevention.
Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
Sophia Y
SY
Kim
Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
Charles E
CE
Spritzer
Duke Sports Medicine Center, Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA.
Gangadhar M
GM
Utturkar
Duke Sports Medicine Center, Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA.
Alison P
AP
Toth
Duke Sports Medicine Center, Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA.
William E
WE
Garrett
Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA Duke Sports Medicine Center, Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA lou.defrate@duke.edu.
Louis E
LE
DeFrate
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000293:injuries; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis / Q000503:physiopathology*; D007719:Knee Joint / Q000473:pathology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016059:Range of Motion, Articular; D055815:Young Adult
MRI; anterior cruciate ligament; contusion; imaging; injury; mechanism; motion; valgus