The influence of femoral tunnel length on graft rupture after anterior cruciate ligament reconstruction

BACKGROUND: For ACL reconstruction, the minimum length of the femoral tunnel and the flexor tendon graft length needed within the tunnel for proper integration have not been defined. The aim of this study was to assess whether a short tunnel is a risk factor for poor prognosis and re-rupture by comparing the outcomes of patients with short femoral tunnels to those of patients with longer tunnels. MATERIALS AND METHODS: A retrospective observational study of 80 patients who underwent ACL reconstruction using flexor tendons via the medial transportal or transtibial technique was performed. Patients were categorized according to the amount of graft within the tunnel: ≤1.5 versus >1.5 cm; ≤2 versus >2 cm; ≤2.5 versus >2.5 cm; and ≤1.5 versus >2.5 cm. Patients were evaluated 2 years after surgery by performing a physical examination (Lachman, pivot shift and anterior drawer tests), using a KT1000 arthrometer, calculating objective and subjective International Knee Documentation Committee scores, conducting the Lysholm score, and recording re-ruptures. RESULTS: Of the 80 operated patients, nine were lost to follow-up. Comparative assessment of the patients with different amounts of graft within the tunnel indicated no significant differences in the evaluated outcomes, except for positive Lachman test results, which were more frequent in patients with tunnels with ≤2 cm of graft than in those with tunnels with >2 cm of graft. CONCLUSION: The amount of graft within the femoral tunnel does not appear to be a risk factor for clinical instability of the knee or re-rupture of the graft. Level of evidence: case series, level IV. LEVEL OF EVIDENCE: Case series, level IV.