Creation of femoral tunnel by outside-in technique for ACL reconstruction: an analysis

Abstract

Purpose: To study the outcome of ACL reconstruction by retrograde outside-in (OI) creation of femoral tunnel.

Methods: ACL reconstruction was done in 41 cases by OI technique. The tip of 115° femoral guide was placed at posterior aspect of femoral foot print of ACL. Reaming was done from outside-in over guide pin. The length of femoral tunnel was obtained by measuring guide pin. The location of intra-articular femoral tunnel aperture and graft was recorded. Tibial tunnel was created with 50° guide placed at tibial foot print of ACL. Post-operative digital radiograph was taken. Antero-posterior view was used to calculate coronal inclination of femoral tunnel. On lateral view femoral tunnel location was marked in relation to the intersection of Blumensaat line and posterior femoral cortical line. Lysholm scoring and pivot shift test were performed at follow-up. Objective measurement of anterior tibial translation was done by rolimeter (aircast) at 1 year.

Results: The mean femoral tunnel length recorded was 39.5 mm (±3.4). There was no incidence of femoral tunnel blow out or graft impingement. All cases had femoral tunnel aperture location posterior to posterior femoral cortical line and inferior to Blumensaat line. The mean coronal angle of femoral tunnel was 30.39° (±4.6). The mean preoperative Lysholm score of 53.5 (±13) increased to 95.2 (±3.5) 1 year after surgery. All the patients had full range of motion. The pivot shift test was negative and instrumented measurement of anterior translation of tibia was near normal in all cases.

Conclusion: OI technique of ACL reconstruction is a simple reproducible technique. The unconstrained placement and angling of femoral guide result in a femoral tunnel which is through footprint of ACL. The graft is placed very low, oblique and as posterior as possible on femoral side mimicking the native ACL.

Level of evidence: III.