Comparison of short-term results of bone tunnel enlargement between EndoButton CL and cross-pin fixation systems after chronic anterior cruciate ligament reconstruction with autologous quadrupled hamstring tendons.

We performed arthroscopic anterior cruciate ligament (ACL) reconstructions of chronic ACL rupture with autologous hamstring tendon grafts in males (mean age 23.9 years). Thirty-two cross-pin fixations and 24 EndoButton CL fixations were performed on the femoral side. Distal fixations on the tibial side were maintained with interference screws plus a staple. Tunnel enlargement was evaluated using X-rays. Femoral and tibial tunnels were measured at three levels 5 mm apart, and average enlargement was calculated after correction for magnification. Tunnel enlargement 12 months after surgery was greater for the EndoButton CL system (femoral side 43.71%, tibial side 51.11%) than for the cross-pin system (femoral side 32.61%, tibial side 25.62%); the difference was significant only on the tibial side. Both proximal fixation techniques were judged clinically successful (follow-up 16 - 36 months). The far fixation point in the EndoButton CL group may be related to mechanical loosening.