• BACKGROUND
    • This study aimed to investigate the graft isometry of anatomical single-bundle anterior cruciate ligament (ACL) reconstruction using a novel method.
  • METHODS
    • Seventy-three patients (mean age, 28.4 ± 9.5 years, 71 men and 2 women) underwent unilateral ACL reconstruction using hamstring autografts and an anteromedial drilling technique. Femoral tunnels were positioned in the high portion of the anteromedial bundle insertion; tibial tunnels were positioned at the center of the ACL tibial footprint. Graft laxity was evaluated using a new method based on Endobutton flip. Two knots were tied on the pulling sutures of the Endobutton, and the distance changes between the knots during flipping were measured, which represented the extent of flipping and the graft laxity. Measurements were conducted at 0°, 30°, 60°, 90°, and 120° of knee flexion, respectively. The patterns of graft laxity and their association with femoral tunnel positions were analyzed.
  • RESULTS
    • The grafts were taut at knee extension but exhibited laxity during knee flexion in nearly all patients. Three patterns of graft laxity were observed: pattern 1, constant laxity throughout flexion (n = 39); pattern 2, lax at mid flexion, and taut again at high flexion (n = 11); and pattern 3, gradually increasing laxity with knee flexion (n = 15). Compared to pattern 1, the femoral tunnels were significantly higher and shallower in pattern 2 and significantly lower and deeper in pattern 3.
  • CONCLUSIONS
    • Positioning a graft in the high portion of the anteromedial bundle insertion on the femoral side does not achieve absolute isometry, but exhibits laxity changes similar to the overall pattern presented by the native ACL during the range of knee motion. Minor variations in the positions of femoral tunnels are associated with distinct patterns of graft laxity. Tensioning and fixation of the ACL graft at knee extension are suggested.