Abstract
We aimed to investigate how increased or decreased femoral antetorsion would affect
the biomechanics of the knee in an anterior cruciate ligament (ACL)-deficient cadaveric
model. We hypothesized that external or internal rotation of the distal femur, achieved
through a femoral osteotomy, would affect the magnitude of tibiofemoral translation
and rotation. Navigated measurements of tibiofemoral translation and rotation during
the anterior drawer, Lachman, and pivot shift tests were performed on six whole-body
cadaveric specimens in each of the following four conditions: native, ACL-deficient
knee, ACL-deficient knee and 20-degree internal distal femur rotation, and ACL-deficient
knee and 20-degree external distal femur rotation. Increased femoral antetorsion significantly
reduced anterior tibial translation in the ACL-deficient knee during the anterior
drawer, Lachman, and pivot shift tests (p < 0.05). Conversely, decreasing femoral antetorsion resulted in an increase in anterior
tibial translation in the anterior drawer (nonsignificant), Lachman (p < 0.05), and pivot shift (p < 0.05) tests. Internally rotating the distal femur significantly reduced the magnitude
of tibial rotation during the pivot shift test in the ACL-deficient knee (p < 0.05), whereas external rotation of the distal femur significantly increased tibial
rotation (p < 0.05). The magnitude of femoral antetorsion affects tibiofemoral translation in
an ACL-deficient cadaveric mode. Internally rotating the distal femur 20 degrees reduced
the magnitude of tibial translation and rotation similar to that of the native knee,
whereas externally rotating the distal femur aggravated translational and rotational
instability.
Keywords
femoral antetorsion - tibiofemoral translation - tibiofemoral rotation - pivot shift
test - biomechanics
