Anatomic double-bundle anterior cruciate ligament reconstruction: kinematics and knee flexion angle-graft tension relation.
OBJECTIVE
The purpose of this study was to compare the bundle tension curves and resultant knee kinematics between 2 tensioning protocols in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.


METHODS
Anatomic double-bundle ACL reconstruction was performed in 7 male cadaveric knees. Each graft was tensioned to 22 N under 2 conditions: (1) both bundles tensioned at 20 degrees of knee flexion (20/20 protocol) or (2) posterolateral (PL) bundle tensioned at 15 degrees and anteromedial (AM) bundle at 45 degrees (45/15 protocol). Knee kinematics were recorded in response to anterior and combined rotatory loads in the intact, ACL-deficient, and reconstructed states. Bundle tension was recorded dynamically with knee motion and during each loading test.


RESULTS
Tensioning both bundles at 20 degrees of knee flexion resulted in a reciprocal bundle tension pattern that was not statistically different; the PL bundle tension was greater than the AM bundle tension in full extension, and the AM bundle tension was greater than the PL bundle tension from 25 degrees to 120 degrees. In the second tensioning protocol, the AM bundle tension was significantly greater than the PL bundle tension at all flexion angles. Both tensioning protocols restored normal knee kinematics.


CONCLUSIONS
Bundle-tensioning protocol is a variable that has a significant effect on the bundle-loading patterns in double-bundle ACL reconstruction. The 20/20 protocol resulted in AM and PL bundle-loading patterns that were equivalent during dynamic testing, whereas the 45/15 protocol led to excessive tension in the AM bundle in full extension. We recommend equal tensioning of both bundles with the knee at 20 degrees of flexion to restore relatively normal tension curves in each bundle and to avoid excessive stress on the AM bundle.


CONCLUSIONS
In double-bundle ACL reconstruction, there is no consensus regarding bundle-tensioning protocols. This study provides data on the individual bundle tension curves that result from 2 commonly used tensioning protocols. These data will assist clinicians as the technique and application of double-bundle ACL reconstruction move forward.
Murray
Patrick J
PJ
Clarkstown Orthopedics, West Nyack, New York 10994, USA. murrayp73@hotmail.com
Alexander
Jerry W
JW
Gold
Jonathan E
JE
Icenogle
Kurt D
KD
Noble
Philip C
PC
Lowe
Walter R
WR
D000328:Adult; D000843:Ankle Joint / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D001864:Bone Wires; D002102:Cadaver; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D008875:Middle Aged; D016059:Range of Motion, Articular; D019651:Plastic Surgery Procedures / Q000379:methods*; D013314:Stress, Mechanical; D013537:Sutures; D013977:Tibia / Q000601:surgery; D016474:Weight-Bearing