Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Sports medicine

Background:

• Graft-tunnel motion is a critical factor in anterior cruciate ligament (ACL) reconstruction outcomes.
• Understanding the biomechanics of hamstring tendon grafts within femoral bone tunnels is essential for optimizing fixation techniques.

Purpose of the Study:

• To quantify the relative motion of quadruple hamstring grafts within the femoral bone tunnel (graft-tunnel motion) under varying tensile loads.
• To evaluate the influence of different polyester tape loop lengths on graft-tunnel motion.

Main Methods:

• Human cadaveric femurs with quadruple hamstring grafts were used, fixed with titanium buttons and polyester tape (15, 25, 35 mm loops).
• Uniaxial tensile loads (50-300 N) were applied using a materials testing machine while the femur remained stationary.
• Graft-tunnel motion was measured using a high-resolution video system tracking markers on the graft and tunnel entrance.

Main Results:

• Graft-tunnel motion ranged from 0.7 +/- 0.2 mm to 3.3 +/- 0.2 mm.
• Motion significantly increased with higher tensile loads (P < 0.05).
• Shorter tape lengths (15 mm) demonstrated significantly less motion compared to longer lengths (35 mm) (P < 0.05).

Conclusions:

• Significant graft-tunnel motion occurs with this fixation technique, particularly under early postoperative stress.
• Minimizing graft-tunnel motion by using shorter tape fixation is recommended.
• Development of alternative fixation methods is needed to further reduce graft-tunnel motion and improve graft incorporation.