Femoral Screw Divergence via the Anteromedial Portal Using an Outside-In Retrograde Drill in Bone-Patella Tendon-Bone Anterior Cruciate Ligament Reconstruction: A Cadaveric Study.
OBJECTIVE
To assess screw divergence when inserting an interference screw for a bone-patellar tendon-bone graft using an outside-in technique with a retrograde drill to create the femoral tunnel.


METHODS
Ten cadaver specimens underwent anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft, with 23-mm-deep tunnels created by a retrograde drill outside-in technique. Drilling angles were based on a previous study that established the optimal angles to recreate the anterior cruciate ligament footprint. To ensure that screw insertion angles matched the angle of socket drilling, a marking pen was used to transpose 2 lines on the skin of the anterior knee corresponding to the drill in both the coronal and axial planes with the knee held at 90° of flexion. The femoral-sided bone plug was affixed with a 7 × 23 mm interference screw through an anteromedial portal. Computed tomography scans were used to calculate coronal and sagittal screw-tunnel divergence.


RESULTS
The median screw divergence in the coronal plane was 2.79°, with a range of 1.1° to 17.2°. Of 10 specimens, 8 had no divergence (0° to 5°), 0 screws were between 5° and 10°, 1 screw was between 10° and 15°, and 1 screw was between 15° and 20°. The 95% confidence interval was 3.73° to 11.69°. No screws had ≥20° of divergence. In the sagittal plane, the median screw divergence was 5.68°, with a range of 1.2° to 18.7°. Five specimens had no divergence (0° to 5°), 3 screws were between 5° and 10°, 0 screws were between 10° and 15°, and 2 screws were between 15° and 20° of divergence. The 95% confidence interval was 3.73° to 11.69°. No screws had ≥20° of divergence.


CONCLUSIONS
The results of this study showed that 80% of screws diverted less than 5° in the coronal plane. In the sagittal plane, only 50% of screws were found to have divergence of 5° or less. No screw in either plane had divergence of greater than or equal to 20°.


CONCLUSIONS
When using a retrograde drill, a skin marking technique is a useful aid in placing interference screws with acceptable angles of divergence when using an inside-out technique.
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
Jason
J
Capo
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.. Electronic address: danieljameskaplan@gmail.com.
Daniel J
DJ
Kaplan
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
David J
DJ
Fralinger
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
Soterios
S
Gyftopolous
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
Eric J
EJ
Strauss
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
Laith M
LM
Jazrawi
Department of Orthopaedic Surgery, Sports Medicine Division (J.C., D.J.K., D.J.F., E.J.S., L.M.J., M.J.A.), and Department of Radiology, Musculoskeletal Division (S.G.), NYU Hospital for Joint Diseases, New York, New York, U.S.A.
Michael J
MJ
Alaia
D000070598:Anterior Cruciate Ligament Injuries / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D064594:Bone-Patellar Tendon-Bone Grafts; D002102:Cadaver; D005269:Femur / Q000601:surgery; D006801:Humans; D010329:Patella / Q000601:surgery; D016059:Range of Motion, Articular; D014057:Tomography, X-Ray Computed