2015 ISAKOS Biennial Congress ePoster #1238

The Effect of Anterior Cruciate Ligament Graft Rotation on Knee Biomechanics

LEVENT Surer, MD, Pittsburgh, PA UNITED STATES
Kostas Michail, MD, MSc, PhD, Pittsburgh, PA UNITED STATES
Murat Köken, ASISTAN, ANKARA TURKEY
Can Yapici, ASISTAN, İSTANBUL TURKEY
Junjun Zhu, BS, MS, Pittsburgh, PA UNITED STATES
Brandon D. Marshall, MS, Pittsburgh, PA UNITED STATES
Monica A. Linde, MS, RN, Pittsburgh, PA UNITED STATES
Patrick J. Smolinski, PhD, Pittsburgh, PA UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES

UNIVERSITY OF PITTSBURGH, PITTSBURGH, PA, USA

FDA Status Cleared

Summary: EVALUATE TO KNEE BIOMECHANICS EFFECTS OF ROTATING THE DISTAL END OF THE BONE-PATELLAR TENDON GRAFT DURING 'ANATOMIC' ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

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Abstract:

THE EFFECT OF ANTERIOR CRUCIATE LIGAMENT GRAFT ROTATION ON KNEE BIOMECHANICS

Surer L1, Michail K1, Koken M1, Yapici C1, Zhu J2, Marshall B2,
Linde-Rosen M1, Smolinski P1,2 , Fu FH 1,2

1Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA
2Department of Mechanical Engineering and Material Science, University of Pittsburgh, PA

Anatomic anterior cruciate ligament (ACL) reconstruction is gaining popularity with the goal to restore the native anatomy and natural collagen orientation of the ACL. However, the effect of graft rotation with tunnel placement on knee biomechanics with anatomic ACL reconstruction is still not well known. The objective of this study was to evaluate the knee biomechanics effects of rotating (twisting) the distal end of the bone-patellar tendon graft with anatomic anterior cruciate ligament reconstruction.

Methods

Twenty (n = 20) mature porcine knees were tested using a robotic testing system. Two groups were created and three knee states were compared: (1) intact ACL, (2) ACL-deficient and (3) anatomic single bundle ACL reconstruction with a) non-rotated graft or b) with rotated graft (anatomical external fiber rotation) with knee in 90º of flexion during arthroscopy. The porcine bone patellar tendon was used as a graft. Anterior tibial translation (ATT), internal rotation, external rotation and in situ force of each graft were measured at different flexion angles. The graft was fixed at 60º of flexion (full extension of porcine knee is 30º) with a 40 Nm tension and each knee was subject to two loading conditions: an 89 N anterior tibial (AT) load and 4 Nm internal (IR) and external tibial (ER) rotational torques. The kinematics and in situ force obtained from the different knee states were compared. Statistical analysis was performed using one-way ANOVA with significance at p < 0.05.

Results

The ATT was significantly higher in both reconstructions from the intact ACL at 60º and 90º of flexion (p<0.05). A significantly higher in situ force was found in the reconstructed knees compared to the intact knees under anterior tibial loading at 60º and 90º of flexion (p < 0.05). There was no difference in IR and ER between the intact knees and reconstructions. The in situ force under IR loading for both reconstructions was higher than that of the ACL at 30º of flexion and was higher for the neutral graft compared to the ACL at 60º of flexion. Under ER loading, there was no significant difference in the in situ force carried in both reconstruction grafts and the intact ACL.

Conclusion

Unlike previous studies, with anatomic ACL reconstruction, the graft rotation had minimal effect on anterior stability and rotational stability in the porcine knee.