PURPOSE: This study evaluates the outcomes of remnant-preserving Anterior cruciate ligament reconstruction (ACLR) using Achilles tendon allografts, focusing on tibial tunnel widening and complications. The primary research question is whether this technique results in significant tunnel widening and other complications. METHODS: We performed a retrospective analysis of 396 patients who underwent ACLR with Achilles tendon allografts between 2010 and 2023. Magnetic resonance imaging (MRI) scans were taken post-operatively and at follow-up, with tunnel width measured at both time points. Tunnel width was measured perpendicular to the tunnel's long axis, assessing both anteroposterior and mediolateral dimensions, 1 cm distal to the articular surface. The cross-sectional area (CSA) of the tibial tunnel was calculated by multiplying the two measured widths. Statistical analysis included paired RESULTS: Follow-up MRI scans of 179 patients showed a non-significant increase in the tibial tunnel CSA of 3.49 mm CONCLUSION: This study demonstrates that remnant-preserving ACL reconstruction using Achilles tendon allografts does not lead to significant tibial tunnel widening and has low complication rates, indicating that it is a safe and effective technique. LEVEL OF EVIDENCE: Level IV, case series.