Cadaveric Study Comparing the Biomechanical Properties of Grafts Used for Knee Anterolateral Ligament Reconstruction

Abstract

To measure the biomechanical properties (maximum load, stiffness, and elongation) of the anterolateral ligament (ALL), gracilis, and iliotibial band (ITB) within the same subject. Thirteen unpaired knees were used (7 women, 6 men). The donors had a mean age at death of 54years (range: 37 to 70years). The mechanical properties of two types of ALL grafts were evaluated: ITB and two-strand gracilis. The mechanical properties of ALL were also measured. Validated methods were used to perform the tensile tests to failure and to record the results. Student's t-test was used to compare the various samples. The maximum load to failure was 141N (±40.6) for the ALL, 200.7N (±48.7) for the gracilis, and 161.1N (±27.1) for the ITB. Only the gracilis had a significantly higher failure load than ITB and ALL (P= .001 and P= .03). The stiffness was 21Nmm-1 (±8.2) for the ALL, 131.7Nmm-1 (±43.7) for the gracilis, and 39.9Nmm-1 (±6) for the ITB. The elongation at failure was 6.2mm (±3.2) for the ALL, 19.9mm (±6.5) for the gracilis, and 20.8mm (±14.7) for the ITB. The gracilis had the highest maximum load to failure. The ITB's mechanical properties most closely resemble those of the ALL. The biomechanical properties of each potential ALL graft can be factored in when deciding which type of graft to use.