Timeline of tibial tunnel expansion after single-incision hamstring anterior cruciate ligament reconstruction

Purpose: The purpose of this study was to determine the time frame for tibial tunnel expansion in patients undergoing anterior cruciate ligament (ACL) reconstruction with hamstring autografts using an endoscopic technique. Does this expansion occur immediately after surgery or over the first 12 weeks of rehabilitation? Type of Study: Observational study involving 10 patients. Methods: The single incision technique used a transtibial approach for drilling the femoral tunnel. Femoral fixation was accomplished with a closed-loop EndoButton (Acufex, Smith Nephew; Mansfield, MA) and tibial fixation with a soft tissue screw and washer augmented by a polylactic acid interference screw. Computed tomography (CT) scans were taken in a consistent manner at weeks I and 12 after surgery to measure tibial and femoral tunnel expansion. Results: The CT scans showed significant widening of the tibial tunnel between 1 and 12 weeks (mean area of tibial tunnel increased from 82.5 to 112.7 mm 2; P = .001). Expansion of the femoral tunnel was also seen; however, this change was not statistically significant (P = .18). Conclusions: The expansion after surgery occurred over time, not immediately after surgery, and was probably caused by factors other than surgical technique. The significance of tibial tunnel expansion needs to be clinically correlated with a long-term study on the effect of tunnel expansion on graft survival.