Summary

When a lateral extrarticular tenodesis is fixed by the use of a bone tunnel, the risk of collision with the femoral ACL tunnel exist, and this collision may increase the risk of ACL failure

Abstract

Objectives: to analyze the risk of anterior cruciate ligament (ACL) graft failure in the case of collision between the femoral tunnels of the ACL and the modified Lemaire lateral extraarticular tenodesis (LET).

Methods

a prospective analysis of 80 consecutive patients have been performed. In all the patients a combined trans anteromedial portal ACL hamstring reconstruction using cortical suspensory device at the femur have been done. Additionally, a modified Lemaire LET have been performed, fixing an 1x8cm iliotibial band strip through a tunnel of 6x20mm by an interferential screw. Exclusion criteria were patients with less than 18 or more than 50 years and multiligament reconstruction. Postoperative CT scan of all the patients have been carried out and two independent observers evaluated the CT scans measuring any degree of collision of the two femoral tunnels and the shortest distance between them. The patients were divided in 3 groups depending on the distance between the two tunnels: group 1 subjects with collision between the tunnels (0mm of distance), group 2 subjects with distance between tunnels of 0 to 5mm and group 3 patients with distance between tunnels > than 5mm. Clinical follow up was performed up to 5 years postoperatively looking for graft cumulative failure. The cumulative failure was defined by the presence of clinical failure and/or graft rupture. Clinical failure was defined as the presence of a patient-reported feeling of giving way and an abnormal KT-1000 side-to-side difference ≥4mm. A graft rupture was defined by MRI evidence of graft discontinuity.

Results

Tunnel collision occurred in 14 of 80 cases (17.5%) and the bone bridge between the tunnels was less than 5 mm in 18 cases (22.5%). In 48 cases (60%) the distance between the two tunnels was more than 5mm. The ICC obtained was considered excellent (0.94; 95% CI, 0.90 to 0.95), and the high calculated k coefficient (0.93; 95% CI, 0.88 to 0.95) showed excellent agreement between observers. A graft rupture occurred in 2 patients in group 1, in 1 patient in group 2 and 1 patient of group 3. A clinical failure was detected in 4 patients of group 1. The cumulative failure was significatively higher in group 1 (p=0,011). All the clinical failures occurred within the first postoperative year. The graft ruptures in group 1 occurred at 14 and 12 months postoperatively and the one in the group 2 occurred at 30 months postoperatively and the one in group 3 at 18 months postoperatively.

Conclusions

the collision between the femoral tunnels of the ACL and the LET can increase the risk of ACL failure. Further studies with higher number of patients are necessary to confirm this data.