Success of ACL reconstruction requires solid graft incorporation within the tunnels to enable graft remodeling. Resorbable interference screws (RIS) provide limited tendon-bone contact because much of the tunnel circumference is occupied by the screw itself, while adjustable suspensory fixation (ASF) systems provide larger contact zones which favor ligamentization.

To evaluate ligamentization of four-strand semintendinosus (4ST) within the tibial bone tunnel using MRI at 6 postoperative months, fixed with ASF compared to RIS.

Prospective comparative study; level II.

The authors prospectively enrolled 121 consecutive patients undergoing primary ACL reconstruction using single bundle 4ST. The femoral graft was fixed using suspensory fixation in all knees. The tibial graft was fixed using ASF in 67 knees and using RIS in 44 knees. Six months postoperatively, knee laxity measurements were taken and MRI scans were performed to assess graft incorportation within the tibial tunnel.

At 6 months follow-up, MRI scans of 109 knees were available for analysis. Tunnel enlargement in the ASF group was 2.3±1.1mm (range, 0.5–6.0), while in the RIS group it was 4.7±2.8mm (range, 0.5–19.0) (P>0.001). Howell graft signal assessment was excellent in 97% of cases in the ASF Group and in 25% of cases in the RIS group (P>0.001). The SNQ was 0.078±0.62 in the ASF group and 0.671±0.83 in the RIS group (P>0.001).

ASF provides more favorable conditions than RIS for incorporation and ligamentization of 4ST grafts within the tibial tunnel. The ASF system used showed very little tunnel widening, which suggests that it grants stabilization. The SNQ was also considerably better in the ASF group, mainly due to tight graft folding that prevented synovial fluid penetration in the graft-bone interface.

The findings are relevant for choice of tibial fixation device for ACL reconstruction particularly in patients that need to resume athletic activities.