Purpose of the study: The isometric position of the femoral tunnel is a critical element for successful anterior cruciate ligament (ACL) repair. An overly wide tunnel can compromise long-term results, requiring revision. The purpose of this prospective study was to evaluate the incidence of femoral tunnel widening on two fixation systems and to determine its impact on clinical outcome.
Material and methods: This prospective study included 80 four-strand hamstring ACL reconstructions. In group A, the titanium cross pinning method was used for fixation (Arthrex, Transfix) 30 mm from the Blumensaat line. In group B, two bioabsorble crossed pins (Mitek, Rigid Fix) were used 13 mm from the «anatomic» fixation. The two groups were similar for age, gender, degenerative disease and type of tibial fixation. Radiographic findings were noted at postop, and 6, 12 and 24 months follow-up. The diameter of the femoral tunnel was measured on the ap and lateral views. The diameter of the tunnel was compared with the drilled diameter. Outcome was assessed with the IKDC score and KT1000 arthrometry.
Results: Two-year follow-up data was available for 66 patients (34 in group A and 32 in group B). Postoperatively, tunnel widening was not significant in either group. At six months, the diameter of the tunnel had increased 62% in group A and 49% in group B. At one year, tunnel diameter decreased 24% in group A and 21% in group B. No significant difference was noted at 24 months. At two years, the tunnel diameter was not correlated with clinical outcome.
Discussion and conclusion: Widening of the femoral fixation tunnel does not alter long-term outcome of ACL reconstructions. While no significant difference was observed for the fixation systems studied in the present analysis, radiographic widening appears to be less for fixations closer to the «anatomic» fixation.