title: Femoral rollback after cruciate-retaining and stabilizing total knee arthroplasty.
abstract: Limited data comparing the kinematics of posterior cruciate ligament-retaining or substituting total knee arthroplasty with its own intact knee under identical loadings is available. In the current study, posterior femoral translation of the lateral and medial femoral condyles under unloaded conditions was examined for intact, cruciate-retaining, cruciate ligament-deficient cruciate-retaining and posterior-substituting knee arthroplasties. Cruciate-retaining and substituting total knee arthroplasties behaved similarly to the cruciate-deficient cruciate-retaining total knee arthroplasty between 0 degrees and 30 degrees flexion. Beyond 30 degrees, the posterior cruciate-retaining arthroplasty showed a significant increase in posterior translation of both femoral condyles. The posterior cruciate-substituting arthroplasty only showed a significant increase in posterior femoral translation after 90 degrees. At 120 degrees, both arthroplasties restored approximately 80% of that of the native knee. Posterior translation of the lateral femoral condyle was greater than that observed in the medial condyle for all knees, indicating the presence of internal tibial rotation during knee flexion. The data showed that the posterior cruciate ligament is an important structure in posterior cruciate-retaining total knee arthroplasty and proper balancing is imperative to the success of the implant. The cam-spine engagement is valuable in restoring posterior femoral translation in posterior cruciate-substituting total knee arthroplasty.
authors.affiliation: Orthopedic Biomechanics Laboratory, The Massachusetts General Hospital and the Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Ephrat
authors.initials: E
authors.lastname: Most
authors.forename: Shay
authors.initials: S
authors.lastname: Zayontz
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
authors.forename: Erik
authors.initials: E
authors.lastname: Otterberg
authors.forename: Kenneth
authors.initials: K
authors.lastname: Sabbag
authors.forename: Harry E
authors.initials: HE
authors.lastname: Rubash
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012399:Rotation; D013977:Tibia / Q000502:physiology