2015 ISAKOS Biennial Congress ePoster #1237

Effect of Graft Size and Insertion Site Area in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Human Cadaver Study

Yusuke Sasaki, MD, asahikawa JAPAN
Masataka Fujii, MD, PhD, Okayama JAPAN
Patrick J. Smolinski, PhD, Pittsburgh, PA UNITED STATES
Monica A. Linde, MS, RN, Pittsburgh, PA UNITED STATES
Daisuke Araki, MD, PhD, Kobe, Hyogo JAPAN
Brandon Mershall, PhD, Pittsburgh, PA UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES

University of Pittsburgh, Pittsburgh, PA, USA

FDA Status Not Applicable

Summary: The purpose of this study was to assess the correlation between the percentage of insertion site restoration and knee kinematics in single bundle ACL reconstruction.

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Abstract:

Introduction

“Anatomic” anterior cruciate ligament (ACL) reconstruction is defined as the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites.
However, many studies pointed out the difference between the area of femoral insertion, tibial insertion and mid-substance of ACL. Therefore, it is remains controversial as to the ideal size of ACL graft needed to restore the native kinematics.
The purpose of this study was to assess the correlation between the percentage of insertion site restoration and knee kinematics in single bundle (SB) ACL reconstruction.

Material And Methods

Twelve fresh-frozen human cadaveric knees were tested using a robotic/universal force-moment sensor (UFS) system. Prior to testing, we obtained 3 Tesla Magnetic Resonance Imaging (MRI) with a slice thickness of 0.5mm and calculate the insertion boundary on 3 dimension (3D)-MRI using 3D simulation software.
As the sequence of tests was performed and the data acquired, 5 knee states were used:
(1) Intact ACL (2) Deficient ACL (3) SB_30 (4) SB_50 (5) SB_80 (SB_30, SB_50 and SB_80 were reconstructed with the graft of 30% coverage, 50% coverage and 80% coverage of femoral footprint, respectively.)
The following 2 external loading conditions were applied for testing: (1) 89 N anterior tibial load (ATL) (2) combined rotatory load of 5 Nm internal tibial torque and 7 Nm valgus torque which simulates the pivot-shift test (simulated pivot-shift; SPS). Simultaneously, we calculated the anterior tibial translation (ATT), Coupled ATT (obtained by SPS) and In-situ force (ISF) of the ACL or ACL graft.
The ACL bundles were reconstructed with hamstring tendons. The diameter of the graft was set to each percentage of femoral footprint, 30%, 50% and 80%, respectively. ACL reconstruction was performed using arthroscopy. Single tunnel of ACL was placed at the midpoint of the center at the AM and PL bundle footprints in the SB ACL reconstruction. The grafts were fixed with 30°/40N during SB ACL reconstruction, after preconditioning.
Statistical analysis was performed using a 2-factor repeated measures analysis of variance (ANOVA) with knee state and knee angle as the factor. Statistical significance was set at P < .05.
Result:
In response to ATL, the ATT for SB_50, SB_80 was significantly smaller than the Intact ACL at 0°. The ATT for SB_30 was significantly bigger than the Intact ACL over 15°. In response to SPS, the coupled ATT for SB_30 was significantly bigger than the Intact ACL at 15° and 30°. In response to ATL, the ISF for SB_30 was significantly lower than the Intact ACL over 15°. In response to SPS, the ISF for SB_30 was significantly lower than the intact ACL at the all knee flexion angles.

Discussion

As for ATT and Coupled ATT, the knee stability in SB_50 was almost restored to intact state. However, the knee stability in SB_80 was same as SB_50. It showed that the larger graft doesn’t always result in improved stability in SB ACL reconstruction, and about 50% coverage to the ACL insertion may be enough to restore the intact knee stability.