Functional and computed tomography correlation of femoral and tibial tunnels in single-bundle anterior cruciate ligament reconstruction: Use of accessory anteromedial portal.

Abstract

Background:An accessory anteromedial portal (AAMP) has been shown to be effective in placing an anatomically ideal femoral tunnel. It is well known that this is due to the independent femoral drilling which is possible with the AAMP. However very little is known regarding the significance of this reconstruction technique in influencing the functional outcomes of anatomic anterior cruciate ligament reconstruction (ACLR). This study documents the influence of tibial and femoral tunnel positions on functional outcomes of anatomic ACLR using the AAMP.Materials and Methods:41 patients who underwent anatomic ACLR between 2011 and 2013 were included in this prospective cohort study. The primary outcome involved the documentation of femoral and tibial tunnel positions with volume rendering imaging using a three-dimensional computed tomography (3D-CT) done at the end of 1 year. The tunnel position evaluations from the CT images were performed by an independent observer specializing in radiodiagnosis. Functional outcome measures included preoperative and postoperative Lysholm and International Knee Documentation Committee (IKDC) scores (subjective) documented by an independent investigator who was not involved with the surgical procedure, at the end of 1 year.Results:The minimum followup was 1 year. All patients achieved good clinical and functional outcomes postoperatively with no reported complications. Tunnel position evaluations with 3D-CT revealed the average tibial tunnel distance to be 15.5 mm (standard deviation [SD] =2.52) from the anterior border of the tibial plateau and the average femoral tunnel distance to be 14.33 mm (SD = 2.6) from the inferior margin of the medial surface of lateral femoral condyle and 13.72 mm (SD = 2.8) from the posterior margin of the medial surface of lateral femoral condyle. The average tunnel diameters were found to be 7.9 mm (SD = 0.72) for the tibial tunnels and 8.6 mm (SD = 1.07) for the femoral tunnels. Statistically significant correlation between the tibial tunnel distance and the IKDC scores with anterior placement of tibial tunnel were found; however, no such statistical relationship were found between the femoral tunnel positions and the functional outcome measures.Conclusion:AAMP gives an ideal approach to drill the femoral tunnel independently. However, the influence of this tunnel placement on long term functional outcomes of ACLR needs to be assessed on larger cohort of patients.