title: Comparison of single- and double-bundle anterior cruciate ligament reconstructions in restoration of knee kinematics and anterior cruciate ligament forces.
abstract: BACKGROUND
  Anterior cruciate ligament (ACL) deficiency alters 6 degrees of freedom knee kinematics, yet only anterior translation and internal rotation have been the primary measures in previous studies.
  
  
  OBJECTIVE
  To compare the 6 degrees of freedom knee kinematics and the graft forces after single- and double-bundle ACL reconstructions under various external loading conditions.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten human cadaveric knees were tested with a robotic testing system under 4 conditions: intact, ACL deficient, single-bundle reconstructed with a quadrupled hamstring tendon graft, and double-bundle reconstructed with 2 looped hamstring tendon grafts. Knee kinematics and forces of the ACL or ACL graft in each knee were measured under 3 loading conditions: an anterior tibial load of 134 N, a simulated quadriceps muscle load of 400 N, and combined tibial torques (10 N.m valgus and 5 N.m internal tibial torques) at 0 degrees , 15 degrees , 30 degrees , 60 degrees , and 90 degrees of knee flexion.
  
  
  RESULTS
  The double-bundle reconstruction restored the anterior and medial laxities closer to the intact knee than the single-bundle reconstruction. However, the internal rotation of the tibia under the simulated quadriceps muscle load was significantly decreased when compared with the intact knee after both reconstructions, more so after double-bundle reconstruction (P < .05). The entire graft force of the double-bundle reconstruction was more similar to that of the intact ACL than that of the single-bundle reconstruction. However, the posterolateral bundle graft in the double-bundle reconstructed knee was overloaded as compared with the intact posterolateral bundle.
  
  
  CONCLUSIONS
  The double-bundle reconstruction can better restore the normal anterior-posterior and medial-lateral laxities than the single-bundle reconstruction can, but an overloading of the posterolateral bundle graft can occur in a double-bundle reconstructed knee.
  
  
  CONCLUSIONS
  Both single-bundle and double-bundle techniques cannot restore the rotational laxities and the ACL force distributions of the intact knee.
authors.affiliation: Bioengineering Laboratory, Massachusetts General Hospital / Harvard Medical School, 55 Fruit Street, GRJ 1215, Boston, MA 02114, USA.
authors.forename: Jong Keun
authors.initials: JK
authors.lastname: Seon
authors.forename: Hemanth R
authors.initials: HR
authors.lastname: Gadikota
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Wu
authors.forename: Karen
authors.initials: K
authors.lastname: Sutton
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Gill
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
mesh_terms: D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007717:Knee / Q000502:physiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D019651:Plastic Surgery Procedures; D012399:Rotation; D013710:Tendons / Q000601:surgery; D013977:Tibia / Q000601:surgery
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