Codominance of the individual posterior cruciate ligament bundles. An analysis of bundle lengths and orientation.
BACKGROUND
It is unclear how each bundle of the posterior cruciate ligament contributes to posterior knee stability.


OBJECTIVE
Changes in bundle orientation and length occur such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension.


METHODS
Controlled laboratory study.


METHODS
Six fresh-frozen cadaveric knees were studied in a joint-testing rig with individual quadriceps and hamstring muscle loading. Kinematic data for the tibia and femur were obtained at knee flexion angles from 0 degrees to 120 degrees. The joint was then disarticulated, and the insertions of the two bundles on the tibia and femur were digitized.


RESULTS
Length of the anterolateral bundle increased with increasing knee flexion angle from 10 degrees to 120 degrees. Length of the posteromedial bundle decreased with increasing knee flexion angle from 0 degrees to 45 degrees and increased slightly from 60 degrees to 120 degrees. Length of the anteromedial bundle was significantly less than that of the posteromedial at 0 degrees, 10 degrees, and 20 degrees of knee flexion. The anterolateral bundle was significantly more horizontal at flexion angles of 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 45 degrees (P < 0.05). The posteromedial bundle was more horizontal at 120 degrees.


CONCLUSIONS
Changes in orientation take place such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension.


CONCLUSIONS
Double-bundle reconstructions achieve more physiologic knee function.
Ahmad
Christopher S
CS
Center for Shoulder, Elbow, and Sports Medicine, Department of Orthopaedic Surgery and Orthopaedic Research Laboratory, Columbia University, New York, New York 10032, USA.
Cohen
Zohara A
ZA
Levine
William N
WN
Gardner
Thomas R
TR
Ateshian
Gerard A
GA
Mow
Van C
VC
D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology; D016119:Posterior Cruciate Ligament / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology*