2017 ISAKOS Biennial Congress ePoster #1013
Does Bone Plug and Graft Orientation Affect Native Femoral Footprint Coverage in Anterior Cruciate Ligament Reconstruction?
Alexander E. Weber, MD, Los Angeles, CA UNITED STATES
Asheesh Bedi, MD, Ann Arbor, MI UNITED STATES
Jonathan Higgins, BS, Chicago UNITED STATES
Jason Hamamoto, MD, Los Angeles UNITED STATES
Brian J. Cole, MD, MBA, Chicago, IL UNITED STATES
Bernard R. Bach, Jr., MD, Chicago, IL UNITED STATES
Nikhil N. Verma, MD, Chicago, IL UNITED STATES
Midwest Orthopaedics at RUSH, Chicago, IL, UNITED STATES
FDA Status Not Applicable
Regardless of ACL-R technique (AM or TT drilling) orientation of the bone plug/graft does affect native femoral ACL footprint coverage where orienting the bone plug/graft such that the graft collagen is inferior rather than posterior in the flexed knee significantly increases native ACL footprint coverage.
The objective of anterior cruciate ligament reconstruction (ACL-R) is to recapitulate the native ACL anatomy as best as possible. In ACL-R in which a bone plug is placed in a femoral tunnel, the surgeon is able to rotate the bone plug/graft in any orientation prior to fixation; however, the effects of bone plug/graft orientation on ACL footprint coverage are unknown, and may have important implications for graft isometry and anatomy. The purpose of this study was to compare the percentage of native femoral ACL footprint coverage between the two most commonly used bone plug/graft orientations.
Five matched pairs of cadaver knees with no prior knee surgery were used for the study. A standard bone-patellar tendon-bone ACL autograft was harvested from each knee and sized for a 10 mm tunnel. Each knee was placed in a custom-designed rigid clamp in 90 degrees of flexion and the native ACL femoral footprint was identified and measured for surface area with a MicroScribe. Next, each matched pair had one knee assigned to a 10 mm anatomic transtibial (TT) femoral tunnel and the corresponding matched knee assigned to a 10 mm anatomic anteromedial (AM) femoral tunnel. The bone plug of each graft was press-fit into the femoral tunnel with the patellar tendon collagen either posterior or inferior in relation to the 90 degree flexed knee, the most common bone plug orientations utilized for interference screw fixation. The patellar tendon collagen area at the entrance of the femoral tunnel was analyzed with the MicroScribe. The graft was removed, oriented in the orientation not yet tested and the collagen area was again calculated. The digitized graft collagen area in each orientation was overlaid onto the digitized native femoral ACL footprint to generate a percent of native ACL footprint coverage.
The average native ACL femoral footprint area was 110.5 ± 9.1 mm2, with no difference in average area between knees assigned to TT or AM drilling (112.6 ± 2.7 mm2 vs. 108.4 ± 13.0 mm2, p = 0.49). The average femoral tunnel area was 95.4 ± 8.7 mm2, with no difference in average area between TT and AM tunnels (95.5 ± 9.9 mm2 vs. 95.3 ± 8.4 mm2, p = 0.96). The average percentage of native ACL footprint covered by the femoral tunnel was 79.5 ± 11.2%. There was no difference between the percentage of native footprint covered between TT and AM tunnels (76.8 ± 7.8% vs. 82.2 ± 13.7%, p = 0.47). There was significantly greater native ACL footprint coverage when the patellar tendon collagen was oriented inferiorly as compared to posteriorly (75.6 ± 6.3% vs. 65.4 ± 11.4%, p = 0.02).
Regardless of ACL-R technique, orientation of the bone/graft does affect native femoral ACL footprint coverage. Orienting the bone plug/graft such that the graft collagen is inferior rather than posterior in the flexed knee significantly increases native ACL footprint coverage.