Biomechanical assessment of ligament maturation after arthroscopic ligament reconstruction of the anterior talofibular ligament.

Abstract

Background: Many techniques have been described for lateral ankle ligament reconstruction. Although the biomechanical properties of gracilis tendons are different from those of ligaments, the use of a gracilis tendon autograft is a popular option for anatomical reconstruction. Graft maturation and the biomechanical processes over time remain unclear. This study describes changes in graft stiffness following anterior talofibular ligament (ATFL) reconstruction and graft reaction to varus stress.

Hypothesis: The reconstruction would be stiffer than the native ATFL, but would decrease during follow-up.

Methods: Twenty patients were prospectively included after arthroscopic reconstruction of the ATFL and calcaneofibular ligament for ankle stabilization. All patients were followed up 3, 6, and 12 months after surgery to assess graft stiffness by shear wave elastography (SWE) at different angles of varus in the ankle. At one year the EFAS and AOFAS functional scores were obtained. A control group of twenty healthy subjects were included to compare graft stiffness to that of a native ATFL.

Results: The stiffness of the native ATFL in the control group was 12.8 +/- 2.4 kPa in neutral position, 18.4 +/- 4.8 kPa at 15 ° of varus, 31.9 +/- 6.6 kPa at 30 ° of varus. One year after surgery, graft stiffness was statistically higher and averaged 56 +/- 9 kPa, 70.2 +/- 11.6 kPa and 84.9 +/- 10.5 kPa, respectively. Postoperative graft stiffness at three, six, and twelve months was not correlated with any of these scores, reflecting patient satisfaction and good function at one year.

Conclusion: Graft stiffness decreases over time but remains four times stiffer than that of a native ATFL at one year in the neutral position. ATFL graft stiffness at one year during varus stress appears to be different from that of a native ATFL.

Level of evidence: III.