Tunnel widening after ACL reconstruction with different fixation techniques: aperture fixation with biodegradable interference screws versus all-inside technique with suspensory cortical buttons. 5-year data from a prospective randomized trial.

Abstract

The aim of the present study was to examine tunnel widening and clinical outcomes after anterior cruciate ligament reconstruction (ACLR) using two different fixation methods: aperture fixation with biodegradable interference screws versus all-inside ACLR with suspensory cortical buttons. Tunnel widening was assessed using volumetric and diameter measurements on magnetic resonance imaging (MRI) scans directly after surgery, as well as 6months and 2 and 5years postoperatively. Clinical outcomes were assessed after 5years with instrumented tibial anteroposterior translation measurement (KT-1000), single-leg hop testing, and the IKDC, Lysholm, and Tegner activity scores. At the final follow-up, the study population consisted of 21 patients, 12 of whom underwent screw fixation and 9 of whom had button fixation. 3 patients with all-inside ACLR had sustained early repeat ruptures within 6 months after surgery and had to be excluded from the further analysis. With screw fixation, the tibial tunnel volume changed significantly more over time compared to all-inside button fixation, with a larger initial increase at 6months (from postoperative 2.9 ± 0.2 to 3.3 ± 0.2 cm3 at 6months versus 1.7 ± 0.1 to 1.9 ± 0.2 cm3) and a greater final decrease over 2-5years postoperatively (from 3.1 ± 0.2 to 1.9 ± 0.2 cm3 versus 1.8 ± 0.2 ± 0.1 to 1.3 ± 0.1 cm3) (P < 0.001). The femoral tunnel volume remained comparable between the two groups throughout the follow-up period, with an initial 1.6 ± 0.1 cm3 in both groups and 1.2 ± 0.1 vs. 1.3 ± 0.1 after 5years in the screw and button groups, respectively (P ≥ 0.314). The maximum tibial and femoral tunnel diameters were significantly larger with screw fixation at all four time points. Tibial diameters measured 11.1 ± 0.2, 12.3 ± 0.3, 12.3 ± 0.4, and 11.2 ± 0.4mm in the screw group versus 8.1 ± 0.3, 8.9 ± 0.3, 9.1 ± 0.4 and 8.2 ± 0.5mm in the button group (P < 0.001). Femoral diameters measured 8.6 ± 0.2, 10.5 ± 0.4, 10.2 ± 0.3, and 8.9 ± 0.3 versus 7.3 ± 0.3, 8.4 ± 0.4, 8.4 ± 0.3, 7.5 ± 0.3, respectively (P ≤ 0.007). Four patients (33%) in the screw group exceeded a diameter of 12mm on the tibial side after 5years versus none in the button group (not significant, P = 0.104). Tibial anteroposterior translation measurement with KT-1000 after 5years was 2.3 ± 2.4mm in the screw group versus 3.2 ± 3.5mm in the button group (not significant, P = 0.602). There were no significant differences between the groups in any of the other clinical outcomes. Tibial tunnels in ACLR with screw fixation were associated with a larger increase in tunnel volume within the first 2years and a greater decrease up to 5years after surgery, while femoral tunnel volumes did not differ significantly. On the tibial side, the need for staged revision ACLR may be greater after biodegradable interference screw fixation if repeat ruptures occur, especially within the first 2years after primary ACLR. Concerns may remain regarding a higher graft failure rate with all-inside ACLR. II. NCT01755819.