Comparison of Failure Strength Between Metallic and Absorbable Interference Screws

Because of the good initial fixation strength of interfer ence screws used in anterior cruciate ligament recon struction, metal interference screws have become the standard method for fixation of bone-patellar tendon- bone grafts. To avoid some of the complications with metal screws, a bioabsorbable interference screw was developed. Data on fixation strength in older human cadavers indicate a similar failure strength between bioabsorbable and metal screws. We studied the fail ure mechanisms, insertion torques, and fixation strengths of absorbable and metal interference screws in cadaveric knees from young and middle-aged do nors. With identical gap and screw size, the mean insertion torque for the metal screws (mean, 1.5 N-m; SD, 0.8) was significantly higher than for the absorb able screws (mean, 0.3 N-m; SD, 0.19). The mean failure load for the metal screws (mean 640 N; SD, 201) was also significantly higher than for the absorb able screws (mean, 418 N; SD, 118).