Biomechanical comparison of four different fixation techniques for pediatric tibial eminence avulsion fractures

Several different methods have been used to repair tibial eminence avulsion fractures. It is not clear which is the best stabilization method. The purpose of this study was to compare the biomechanical stability of tibial eminence avulsion fractures using suture, resorbable screw, resorbable nail, and metal screw techniques.

Sixteen immature bovine knees were dissected leaving just the anterior cruciate ligament. A fracture was created using a curved osteotome, The knees were randomly stabilized with either 2 single-armed #2 Ethibond sutures, 3 bioabsorbable nails, a single resorbable screw, or a single metal screw. Femurs were tested with the knee flexed to 35 degrees to simulate anterior tibial translation. Tests involved loading between 5 N and 150 N for 200 cycles, then a tensile failure test at 0.5 mm/sec. Cyclic fragment deformation, initial fragment stiffness, and failure load were compared using a 1-way analysis of variance (p < 0.05).

There were no significant mechanical differences across groups. The variability in performance was much greater for both the suture and resorbable screw repairs. Both sutures and resorbable screw constructs resulted in a deformation that was 1 mm greater than that of the resorbable nails or a metal screw.

Increased fracture separation for sutures and resorbable screw groups indicates a potential loss in reduction during cyclic, physiologic loads. Each group could withstand up to 85 lb of tensile force before failure, but it is unlikely that this force would occur with incidental loads during the early rehabilitation period.

There was not a clear biomechanical advantage to performing any particular fixation method in this study. This suggests that the surgeon can use their clinical judgment and experience to determine the fixation technique.