Tunnel Volume Enlargement After Posterior Cruciate Ligament Reconstruction: Comparison of Achilles Allograft With Mixed Autograft/Allograftd-A Prospective Computed Tomography Study

Purpose: The purpose of this study was to evaluate and compare femoral and tibial tunnel volume enlargement (TVE) after arthroscopic posterior cruciate ligament (PCL) reconstruction by remnant bundle preservation using Achilles allograft or mixed graft. Methods: Seventy-eight patients undergoing primary arthroscopic single-bundle PCL reconstruction were initially included. Fifty-six of these patients underwent follow-up for a minimum of 1 year postoperatively and were divided into 2 groups: group A received Achilles allograft (n = 27), and group B received mixed graft (n = 29). The clinical evaluation included the International Knee Documentation Committee rating, Lysholm score, Tegner activity score, and Telos stress test (Telos, Weiterstadt, Germany). All of the patients were evaluated for TVE by computed tomography scanning at the 1-year follow-up; the results were compared with the data from 1 week postoperatively. A volume increment of more than 44%, which indicates 2 mm of widening of the tunnel diameter, was defined as TVE. Results: The overall incidence of TVE after single-bundle PCL reconstruction was 3.6% (2 of 56 patients) for the femoral tunnel and 5.4% (3 of 56 patients) for the tibial tunnel. The overall mean tunnel difference between 1 week postoperatively and the final follow-up was 12.0% for the femoral tunnel and 10.6% for the tibial tunnel. The mean femoral TVE was 10.1% in group A and 13.8% in group B; the mean tibial TVE was 9.9% in group A and 11.2% in group B. These differences were not statistically significant. The functional outcome was improved in both groups, showing no statistical difference at the 1-year follow-up. Conclusions: The femoral and tibial TVE caused by single-bundle PCL reconstruction using the remnant bundle-preservation technique showed no significant differences between the Achilles allograft and the mixed graft over a short-term follow-up. Furthermore, the overall incidence of TVE in PCL reconstruction in this study was low. Level of Evidence: Level II, prospective comparative study.