Tibial Tunnel Widening Following Anterior Cruciate Ligament Reconstruction: A Retrospective Seven-year Study Evaluating the Effects of Initial Graft Tensioning and Graft Selection

Purpose: To investigate tibial tunnel widening in ACL reconstruction patients over seven years to establish the effects of initial graft tension on tibial widening and clinical outcomes when using both patellar tendon (BTB) and hamstring tendon (HS) grafts.

Methods: Ninety patients, who were reconstructed with BTB or HS autografts, were randomized using one of two initial graft tension protocols; 1) tensioned to restore normal anteroposterior laxity ("low-tension"; n = 46) and 2) tensioned to over-constrain anteroposterior (AP) laxity by two millimeters ("high-tension"; n = 44). Seventy patients had post-surgical data with 45 available for review at seven years. Tunnel widening was assessed via radiographs at one-, three-, and seven-year follow-up. Patient-reported outcomes were compared.

Results: The mean ± 95% confidence intervals of the initial diameters for the BTB autografts were 10.3 ± 0.5 mm (Low-tension) and 10.2 ± 0.6 mm (High-tension) with final diameters of 10.8 ± 0.6 mm (Low-tension) and 9.9 ± 0.6 mm (High-tension). The initial diameters for HS autografts were 8.1 ± 0.9 mm (Low-tension) and 8.4 ± 0.7 mm (High-tension) with final diameters of 11.5 ± 1.1 mm (Low-tension) and 11.1 ± 0.9 mm (High-tension). For subjects with HS autografts, mean tunnel diameters significantly changed over time (p < .001); no significant changes were observed in BTB autografts (p = .29). Change in diameter of the HS autograft group remained significantly greater than the BTB group at all time points for both tension groups (p < .05). No differences in patient-reported outcomes were found between tension groups or graft types.

Conclusions: Patients who underwent ACL-R with HS autograft exhibited tibial tunnel widening over seven years. Patients with BTB autografts did not experience widening, regardless of initial graft tension. Patient-reported outcomes were equivalent.