Novel mechanical impact simulator designed to generate clinically relevant anterior cruciate ligament ruptures.
BACKGROUND
Over 250,000 anterior cruciate ligament ruptures occur each year; therefore, it is important to understand the underlying mechanisms of these injuries. The objective of the current investigation was to develop and analyze an impact test device that consistently produces anterior cruciate ligament failure in a clinically relevant manner.


METHODS
A mechanical impact simulator was developed to simulate the ground reaction force impulse generated from landing in a physiologic and clinically relevant manner. External knee abduction moment, anterior shear, and internal tibial rotation loads were applied to the specimen via pneumatic actuators. The magnitudes of applied loads were determined in vivo from a cohort of healthy athletes. Loads were systematically increased until specimen failure was induced. Three cadaveric lower extremity specimens were tested and clinically assessed for failure. Knee specimens were physically and arthroscopically examined at baseline and at post-injury by a board certified orthopedic surgeon.


RESULTS
All three specimens experienced failure at either the midsubstance or the femoral insertion site. The mean peak strain prior to failure was 18.8 (6.2)%, while the mean peak medial collateral ligament strain was 7.9 (5.9)%.


CONCLUSIONS
A board certified orthopedic surgeon confirmed observed rupture patterns were representative of clinical cases. Peak strains were consistent with literature. The novel mechanical impact simulator will allow researchers to assess clinically relevant patterns of rupture and the data generated will inform clinician decisions. This novel machine presents the ability to assess healthy specimens as well as differences in the function of deficient and reconstructed knees.
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA; Sports Medicine Center, Mayo Clinic, Rochester, MN, USA. Electronic address: bates.nathaniel@mayo.edu.
Nathaniel A
NA
Bates
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA; Sports Medicine Center, Mayo Clinic, Rochester, MN, USA.
Nathan D
ND
Schilaty
Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.
Christopher V
CV
Nagelli
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA.
Aaron J
AJ
Krych
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA; Sports Medicine Center, Mayo Clinic, Rochester, MN, USA; Department of Physical Medicine & Rehabilitation, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.
Timothy E
TE
Hewett
D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology*; D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D001835:Body Weight / Q000502:physiology; D002102:Cadaver; D005260:Female; D006801:Humans; D007717:Knee / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D012421:Rupture / Q000503:physiopathology; D013314:Stress, Mechanical; D013977:Tibia / Q000503:physiopathology; D055815:Young Adult
Anterior cruciate ligament; Impact; Injury simulation; Jump landing; Knee ligament biomechanics